JP2003079182A - Motor drive equipment and motor drive method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce vibrations of a motor and electromagnetic sound by using one current detecting resistor, and to prevent a plurality of phase currents from changing suddenly. SOLUTION: This motor drive equipment is provided with a plurality of output circuits having upper and lower arm side switching elements which are connected in series. The equipment comprises the current detecting resistor which is connected in series and in common with the plurality of output circuits, a current conduction phase switching circuit which makes electrical continuity of one side switching element in one of the output circuits for a period to correspond to the prescribed electrical angle, and makes the other side switching elements in the other plurality of output circuits perform switching operation, and a current conduction period control part for forming a signal to control the switching operation in such a manner that a first period and a second period exist in each of a plurality of periods in which the period is divided. In the first period, a plurality of the switching elements are set to be electrically continuous. In the second period, one from among the switching elements which are made electrically continuous successively in the first period, is made to be electrically continuous.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor driving technique, and more particularly to a PWM (pulse width modulation) type motor driving technique.

[0002]

2. Description of the Related Art A triangular wave slice method and a peak current detection method are known as PWM drive methods for brushless motors. The triangular wave slicing method uses an error amplifier that outputs a difference between the voltage generated in the detection resistance and the torque command voltage as a slice level by passing a coil current through the detection resistance, and slices a triangular wave of a constant cycle at this slice level, This is a method of determining the energization period to the coil. The peak current detection method is a method in which the supply of current to the coil is stopped and the regenerative current mode is set when the voltage generated in the current detection resistor through which the coil current flows reaches the torque command voltage without using an error amplifier. .

FIG. 13 is a block diagram of a conventional peak current detection type motor drive device. In FIG. 13, Hall elements 21A, 21B, and 21C detect the position of the rotor of the motor 10, and Hall element outputs S11 and S11 respectively.
It outputs S12 and S13 to the position detection circuit 22. The position detection circuit 22 uses the Hall element outputs S11, S12, S13.
Position signals S21, S22 and S23 based on
It outputs to the energized phase switching circuit 93. Position signals S21, S2
2 and S23 are Hall element outputs S11, S12, S1.
This is a signal obtained by shifting the phase of 3 by 30 °.

The energized phase switching circuit 93 has a position signal S21,
The energized phase is determined according to S22 and S23. At this time, the energized phase switching circuit 93 does not flow the phase current of one of the three phases in order to facilitate the measurement of the phase current. The logic control circuit 95 is set when the reference pulse PI is input, changes the level of the signal output to the energized phase switching circuit 93, and controls the supply of current to the motor 10. The reference pulse PI is a periodic pulse.

FIG. 14 is a graph showing changes with time of each phase current of the motor driven by the motor driving device of FIG. FIG. 14 shows the respective phase currents I1, I2, I3 of the U-phase, V-phase and W-phase, and the currents flowing from the drive transistors 1-6 toward the motor 10 are positive. As shown in FIG. 14, the phase current of one phase is always zero, so that any one of the phase currents changes abruptly at every electrical angle of 60 °.

Now, it is assumed that the logic control circuit 95 is set by the reference pulse PI. The energized phase switching circuit 93 makes only the W-phase upper arm side drive transistor 5 and the U-phase lower arm side drive transistor 2 conductive, for example. At this time, since a current flows through the current detection resistor 7 via the W-phase coil 13 and the U-phase coil 11, the magnitude of this current can be detected as the voltage generated in the current detection resistor 7. Since this current flows through the inductive coil, it gradually increases after the driving transistors 2 and 5 become conductive.

When the current increases and the voltage generated in the current detection resistor 7 reaches the torque command voltage TI, the level of the output of the comparator 96 changes and the logic control circuit 95 is reset. The logic control circuit 95 uses the energized phase switching circuit 93.
Inverts the level of the signal output to the energizing phase switching circuit 9
3 makes the drive transistor 2 non-conductive.

As described above, the period from the setting of the logic control circuit 95 to the resetting thereof is the on-duty period of the switching operation. After the logic control circuit 95 is reset, the currents flowing through the coils 11 and 13 tend to continue flowing, so that the regenerative current flows through the diode 1D existing between the source and drain of the driving transistor 1. Since the regenerative current does not pass through the current detection resistor 7, the voltage generated in the current detection resistor 7 becomes zero during regeneration.

Although the regenerative current gradually decreases, when the reference pulse PI is input again, the logic control circuit 95 is set and the energized phase switching circuit 93 makes the drive transistor 2 conductive. Such an operation is repeated until the energized phase switching circuit 93 switches the energized phase. In this way, the drive current flowing when the logic control circuit 95 is set and the regenerative current flowing when it is reset flow alternately, and as a result, a phase current approximately equivalent to the torque command voltage TI is passed through a predetermined coil. You can

FIG. 15 shows a current detection resistance voltage (motor current detection signal) MC, V near time t = tz in FIG.
It is the graph which expanded the time axis and showed the phase currents I2 and I3 of the phase and the W phase. In FIG. 15, the period T91 is U
This is a period during which the drive currents of the phase and V-phase currents flow, and this current flows through the current detection resistor 7. The period T92 is a period in which U-phase and V-phase currents flow as regenerative currents. Period T93
Is the period during which the U-phase and W-phase drive currents flow, and this current flows through the current detection resistor 7. The period T94 is a period during which U-phase and W-phase currents flow as regenerative current.

[0011]

However, in the conventional motor drive device as shown in FIG. 13, since the phase current changes abruptly as shown in FIG. 14, when the phase current is switched,
There are problems that the motor vibrates and electromagnetic noise is generated.

In order to prevent such a problem from occurring, it is sufficient to control each phase current so as not to change abruptly. However, in order to detect and control a plurality of phase currents, it is necessary to adjust the number of phases. An equal number of current sensing resistors was needed. Since it is difficult to incorporate a current detection resistor in an integrated circuit, if the number of current detection resistors is large, the scale of the device will increase,
There was a problem that it was costly.

Further, since the resistance characteristics generally vary, there is a problem that the current detection characteristics are different for each phase when a current detection resistance corresponding to each phase is used. For example, the magnitudes of the detected currents may be different even when the magnitudes of the two phase currents are actually the same.

The present invention solves the above-mentioned problems and uses a single current detection resistor to control a plurality of phase currents so as not to change abruptly, thereby reducing motor vibration and electromagnetic noise. The purpose is to

[0015]

Means for Solving the Problems In order to solve the above-mentioned problems, the invention of claim 1 provides a plurality of output circuits each having an upper arm side switching element and a lower arm side switching element connected in series. A motor drive device that supplies a current to a motor from a connection point between an upper arm side switching element and a lower arm side switching element in each of the output circuits, the motor driving apparatus being in series with the plurality of output circuits and commonly Of the plurality of output circuits, which are connected, a current detection resistor for detecting a current supplied to the plurality of output circuits, a position detection unit which outputs a position signal according to the position of the rotor of the motor, and a plurality of output circuits One of the switching elements in any one of them is selected according to the position signal, and is made conductive during a period corresponding to a predetermined electrical angle. In the case where the switching element is the upper arm side switching element, the lower arm side switching element in any one of the remaining plurality of output circuits is caused to perform a switching operation so as to conduct the switching element is the lower arm side switching element. Is a conduction phase switching circuit that causes the upper arm side switching element in any one of the plurality of the remaining output circuits to perform a switching operation, and a plurality of periods in which a period corresponding to the predetermined electrical angle is divided, Any one of a plurality of switching elements that perform a switching operation, a first period in which a plurality of switching elements are made conductive, and a plurality of switching elements that are made conductive in the first period
So that there is a second period during which one of them continues to conduct, a switching operation control signal for controlling the switching operation by the energized phase switching circuit is provided according to the input torque command signal and the voltage generated in the current detection resistor. And an energization period control unit for generating and outputting.

According to the invention of claim 1, a first period in which a plurality of switching elements are made conductive and a second period in which one of the plurality of switching elements made conductive in the first period is continuously made conductive Since it has a period of, it becomes possible to control a plurality of phase currents by using one current detection resistor. For this reason, it is possible to perform PWM control in which the magnitudes of the phase currents do not vary from each other, it is possible to avoid sudden changes in the phase currents, and it is possible to reduce vibration and electromagnetic noise of the motor during phase switching.

According to a second aspect of the invention, in the motor drive device according to the first aspect, the energization period control section is
The first target signal corresponding to the target value of the current to be passed through the current detection resistor in the first period, which is determined according to the torque command signal, the torque command signal, and the position signal, A phase-specific torque signal generation circuit that alternately outputs a second target signal corresponding to the target value of the current that should flow in the current detection resistor in the second period, and the voltage generated in the current detection resistor is the phase-dependent torque. It is determined whether or not the output of the signal generation circuit is exceeded, a comparator that outputs the result, a reference pulse that defines the cycle of the switching operation, and the switching operation control signal according to the output of the comparator are output. A logic control circuit for generating and outputting the phase-dependent torque signal for the first period in which the voltage generated in the current detection resistor is generated by the comparator. When it is determined that the output of the generation circuit is exceeded, the first period is ended, and it is determined that the voltage generated in the current detection resistor exceeds the output of the phase-specific torque signal generation circuit for the second period. Then, the switching operation control signal is generated and output so as to end the second period.

According to the invention of claim 2, an appropriate switching operation control signal can be generated.

According to a third aspect of the present invention, in the motor drive apparatus according to the second aspect, the logic control circuit is set by the reference pulse, and the first latch having the output of the comparator as a reset input is used. A second latch set by the reference pulse, an output of the first latch, and an output of the comparator as inputs, and a logic for giving the obtained output to the second latch as a reset input. A circuit for outputting the outputs of the first and second latches as the switching operation control signal, wherein the first latch has an output of the comparator,
The logic circuit is reset when the voltage generated in the current detection resistor exceeds the first target signal, and the logic circuit is configured such that the output of the first latch is the first The output of the comparator is output when the latch indicates that it is reset, and the output of the comparator is not output when the first latch indicates that it is not reset. The second latch is configured such that the logic circuit outputs the output of the comparator, and the output of the comparator is such that the voltage generated in the current detection resistor exceeds the second target signal. It is reset when shown.

According to the third aspect of the present invention, since the logic circuit is included, the operation of the second latch can be ensured and the malfunction of the motor drive device can be reduced.

According to a fourth aspect of the invention, in the motor drive device according to the third aspect, the logic control circuit further includes a delay circuit that delays the output of the first latch for a predetermined time and outputs the delayed output. The first latch provides its output to the logic circuit via the delay circuit.

According to the invention of claim 4, malfunctions due to noise of the second latch can be reduced.

According to a fifth aspect of the invention, in the motor drive device according to the first aspect, the energization period control section is
The first target signal corresponding to the target value of the current to be passed through the current detection resistor in the first period, which is determined according to the torque command signal, the torque command signal, and the position signal, A phase-specific torque signal generation circuit that outputs a second target signal corresponding to a target value of a current that should flow in the current detection resistor in a second period, and a voltage generated in the current detection resistor is the first target signal. And a first comparator that outputs the result and whether the voltage generated in the current detection resistor exceeds the second target signal, and outputs the result. And a logic control circuit that generates and outputs the switching operation control signal according to a reference pulse that defines the cycle of the switching operation and the outputs of the first and second comparators. Wherein the logic control circuit,
When the first comparator determines that the voltage generated in the current detection resistor exceeds the first target signal, the first period is ended, and the second comparator detects the current detection. When it is determined that the voltage generated in the resistor exceeds the second target signal, the switching operation control signal is generated and output so as to end the second period.

According to the invention of claim 5, since the first and second comparators are less likely to malfunction, a stable operation can be performed.

According to a sixth aspect of the present invention, in the motor drive apparatus according to the fifth aspect, the logic control circuit is set by the reference pulse, and the output of the first comparator is used as a reset input. 1 latch, a second latch set by the reference pulse, an output of the first latch, and an output of the second comparator, and the obtained output is used as the second latch. And a logic circuit which is provided as a reset input to the first latch and the second latch, and outputs the outputs of the first and second latches as the switching operation control signal.
When the output of the comparator of indicates that the voltage generated in the current detection resistor exceeds the first target signal,
And the logic circuit outputs the output of the second comparator when the output of the first latch indicates that the first latch is reset, The second latch does not output the output of the second comparator when the first latch indicates that the second comparator is not reset. It outputs an output, and is reset when the output of the second comparator indicates that the voltage generated in the current detection resistor exceeds the second target signal.

According to the sixth aspect of the present invention, since the logic circuit is included, the operation of the second latch can be ensured and the malfunction of the motor drive device can be reduced.

According to the invention of claim 7, in the motor drive device according to claim 2 or 5, the cycle of the reference pulse is substantially constant.

According to the seventh aspect of the present invention, since the cycle of the timing for turning on the drive transistor is constant, it is easy to take a measure for making it less susceptible to the noise generated by switching.

Further, in the invention of claim 8, in the motor drive device according to claim 2 or 5, the torque signal generating circuit for each phase uses a voltage corresponding to the torque command signal as the first target signal. Using a sawtooth wave whose period is a period corresponding to the predetermined electrical angle and whose peak value is substantially equal to the first target signal, based on the position signal and the first target signal. It is used as the second target signal.

According to the eighth aspect of the present invention, the waveform of the phase current can be formed into a substantially trapezoidal shape, and abrupt changes in the phase current can be avoided.

According to a ninth aspect of the invention, in the motor drive device according to the first aspect, the energization period control section is
Of the plurality of switching elements that are made conductive during the first period, those that are made conductive during the second period are made non-conductive until a predetermined time elapses after the start of the first period. As described above, a signal for controlling the switching operation is generated and output as the switching operation control signal.

According to the invention of claim 9, since the currents of the two phases do not start to flow at the same time, the influence of switching noise can be suppressed.

According to a tenth aspect of the invention, as a motor driving method, a plurality of output circuits each having an upper arm side switching element and a lower arm side switching element connected in series are provided, and the plurality of output circuits are connected in series. And a current detection resistor that is commonly connected and that detects a current supplied to the plurality of output circuits, and that connects the upper arm side switching element and the lower arm side switching element in each of the output circuits. In a motor drive device that supplies current to a motor from a point, the step of obtaining a position signal according to the position of the rotor of the motor, and the one switching element in any one of the plurality of output circuits is used as the position signal. The step of making conductive during a period corresponding to a predetermined electrical angle, and the switch making conductive. In the case where the switching element is the upper arm side switching element, the lower arm side switching element in the remaining one of the plurality of output circuits is caused to perform a switching operation, and when the switching element is brought into conduction, the lower arm side switching element is A step of causing the upper arm side switching element in the remaining one of the plurality of output circuits to perform a switching operation, wherein the step of performing the switching operation is divided into periods corresponding to the predetermined electrical angle. In each of the plurality of periods, among the switching elements that perform the switching operation, any one of a first period in which the plurality of switching elements are made conductive and a plurality of switching elements in which the plurality of switching elements are made conductive in the first period There is a second period in which one continues to conduct As described above, according to the torque command signal is input and a voltage generated in the current detecting resistor, and controls the switching operation.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, as an example, a case where the motor drive device drives a three-phase brushless motor will be described.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
It is a block diagram of a motor drive device according to the embodiment of.
The motor drive device of FIG. 1 includes U-phase, V-phase, W-phase upper arm side drive transistors 1, 3, 5 and U-phase, V-phase, W-phase lower arm side drive transistors 2, 4, 6 and diode 1
D, 2D, 3D, 4D, 5D, 6D and current detection resistor 7
A Hall element circuit 21, a position detection circuit 22, an energized phase switching circuit 23, a pre-drive circuit 24, a phase-specific torque signal generation circuit 30, a logic control circuit 40, and a comparator 51. . On the other hand, the motor 10 includes a U-phase coil 11, a V-phase coil 12, and a W-phase coil 13. The phase-based torque signal generation circuit 30, the logic control circuit 40, and the comparator 51 constitute the energization period control unit 100. Hall element circuit 21 and position detection circuit 2
2 constitutes a position detector.

The drive transistors 1 to 6 are n-type MOS
(Metal oxide semiconductor) Suppose that it is a transistor. The source and drain of the drive transistor 1 are
The anode and cathode of the diode 1D are connected to each other. Similarly, diodes 2D to 6D are connected to the drive transistors 2 to 6. The drains of the drive transistors 1, 3, 5 are connected to the power supply VCC, and the sources of the drive transistors 2, 4, 6 are connected to one end of the current detection resistor 7. The other end of the current detection resistor 7 is grounded. The drive transistors 1 to 6 operate as switching elements.

The drive transistors 1 and 2 and the diodes 1D and 2D operate as a U-phase output circuit.
The drive transistors 3 and 4 and the diodes 3D and 4D operate as a V-phase output circuit. The drive transistors 5 and 6 and the diodes 5D and 6D operate as a W-phase output circuit.

The source of the drive transistor 1 is connected to the drain of the drive transistor 2, and the U of the motor 10 is further connected.
It is connected to one end of the phase coil 11. The source of the drive transistor 3 is connected to the drain of the drive transistor 4, and is further connected to one end of the V-phase coil 12 of the motor 10. The source of the drive transistor 5 is connected to the drain of the drive transistor 6, and further connected to one end of the W-phase coil 13 of the motor 10. The other end of the U-phase coil 11 is connected to the other ends of the V-phase coil 12 and the W-phase coil 13.

Here, the current flowing from the drive transistors 1 and 2 toward the U-phase coil 11 is referred to as U-phase current I1. Similarly, drive transistors 3 and 4 to V-phase coil 1
The current flowing toward 2 is the V-phase current I2, and the current flowing from the drive transistors 5 and 6 toward the W-phase coil 13 is the W-phase current I3. In addition, the driving transistors 1 to
The current flowing from 6 toward the coils 11 to 13 is called a discharge current, and the current in the opposite direction is called a suction current. Let the direction of the discharge current be the positive direction of each phase current.
Since the coils 11 to 13 of the motor 10 are Y-connected, each phase current is equal to the current flowing through the corresponding coil.

The hall element circuit 21 is a hall element 21.
A, 21B, 21C are provided. Hall element 21A,
Each of 21B and 21C detects the position of the rotor of the motor 10 and outputs Hall element outputs S11, S12, and S13 to the position detection circuit 22. The position detection circuit 22 obtains the position signals S21, S22, S23 and PS based on the Hall element outputs S11, S12, S13, and the position signal S
21, S22 and S23 are output to the energized phase switching circuit 23, and the position signal PS is output to the phase-specific torque signal generation circuit 30.

The phase-dependent torque signal generation circuit 30 targets the current flowing through the current detection resistor 7 based on the position signal PS, the torque command voltage (torque command signal) TI, the reference pulse PI, and the output CP of the comparator 51. Voltage signal TP corresponding to the value
Is generated and output to the positive input terminal of the comparator 51. The voltage (source potential of the drive transistors 2, 4, 6) generated in the current detection resistor 7 is input to the negative input terminal of the comparator 51 as the motor current detection signal MC. Comparator 51
Outputs the output CP to the phase-based torque signal generation circuit 30 and the logic control circuit 40. Further, the reference pulse PI is input to the logic control circuit 40. The logic control circuit 40 includes switching operation control signals F1 and F that define a period during which the driving transistors 1 to 6 are made conductive.
2 is generated and output to the energized phase switching circuit 23.

The energized phase switching circuit 23 has a position signal S21,
Based on S22 and S23 and the control signals F1 and F2, one of the drive transistors 1 to 6 to be made conductive is selected and the pre-drive circuit 24 is instructed. The pre-drive circuit 24 outputs a signal to the gates of the driving transistors 1 to 6 according to the output of the energization phase switching circuit 23, and controls conduction / non-conduction of the driving transistors 1 to 6.

FIG. 2 shows each phase current I1 to I3 of the motor 10.
3 is a graph showing a target waveform of FIG. The motor drive device of FIG. 1 controls the supply of current to the motor 10 as shown in FIG. 2 so that the phase currents I1 to I3 of the motor 10 do not change suddenly. The motor drive device of FIG.
For example, the electrical angle 360 ° of 0 is divided into six, and the energized phase is changed every period corresponding to the divided electrical angle, that is, every time the rotor of the motor 10 rotates by an angle corresponding to the divided electrical angle. The current of the motor 10 is controlled while switching.

For example, in the period TU1 of FIG. 2, the electrical angle is 60 °.
Is a period corresponding to. In the period TU1, the U-phase current I1
Is the discharge current, and its magnitude is almost constant. The V-phase current I2 is a sink current, and its magnitude gradually decreases with time t. The W-phase current I3 is a sink current, and its magnitude gradually increases from 0 with time t. Therefore, in the period TU1, the U-phase upper-arm side drive transistor 1 is continuously turned on. Further, the V-phase current I2 and the W-phase current I3 are shown in FIG.
Thus, the lower arm side drive transistors 4 and 6 of the V phase and W phase are switched to control the conduction period and the non-conduction period of these drive transistors 4 and 6.

FIG. 3 is a block diagram showing an example of the configuration of the energization period control unit 100 of FIG. Energization period control unit 100
Includes a phase-dependent torque signal generation circuit 30, a logic control circuit 40, and a comparator 51. The phase-based torque signal generation circuit 30 of FIG. 3 includes a double-edge differentiation circuit 31, a constant current source 32, switches 33 and 36, a capacitor 34,
The level control circuit 35 and the RS flip-flop 37 are provided. The logic control circuit 40 of FIG. 3 includes an RS flip-flop 41 as a first latch, an RS flip-flop 42 as a second latch, and a delay circuit 43.
And inverters 44 and 45, and a NAND gate 46. The inverters 44 and 45 and the NAND gate 46 operate as a logic circuit 49.

FIG. 4 is a graph showing signals relating to the position detection circuit 22 and the phase-specific torque signal generation circuit 30. The position detection circuit 22 obtains a position detection signal S21 indicating the rotor position of the motor 10 based on the Hall element outputs S11 and S12. Here, as an example, the Hall element output S
The difference between 11 and S12 is used as the position detection signal S21 (S2
1 = S11-S12). Hall element outputs S11 and S1
Reference numeral 2 is an approximate sine wave, and when the phase of the Hall element output S11 is 120 ° ahead of S12, the phase of the position detection signal S21 is 30 ° ahead of the Hall element output S11. Similarly, the position detection circuit 22 outputs the position detection signals S22 and S23 to, for example, S22 = S12-S13, S2.
3 = S13-S11.

The position detection circuit 22 obtains the position detection signal PS based on the obtained position detection signals S21, S22 and S23. The position detection signal PS rises when the position detection signal S21 changes from negative to positive, and the position detection signal S2 rises.
Pulse that falls when 3 changes from positive to negative, pulse that rises when the position detection signal S22 changes from negative to positive, pulse that falls when position detection signal S21 changes from positive to negative, and position detection signal It is a signal that repeats a pulse that rises when S23 changes from negative to positive and falls when the position detection signal S22 changes from positive to negative. The timing of the edge of the position detection signal PS is, as shown in FIG. 4, Hall element outputs S11, S1.
It is the timing when the waveforms of S2 and S13 cross.

The operation of the torque signal generation circuit for each phase 30 will be described with reference to FIGS. 3 and 4. The position signal PS output from the position detection circuit 22 is supplied to the both-edge differentiation circuit 31.
Has been entered. The both-edge differentiating circuit 31 outputs a reset pulse signal S31 which is “L” for a certain period when detecting an edge of the position signal PS and is “H” at other times to the switch 33 as a control signal (“H”, “H”). L "
Represent logical high potential and low potential, respectively).

One end of the capacitor 34 is connected to the output of the constant current source 32 and is grounded via the switch 33. The other end of the capacitor 34 is grounded. The capacitor 34 is charged by the current output from the constant current source 32, and the switch 33 conducts only when the reset pulse signal S31 is “L” to discharge the capacitor 34. Therefore, the voltage S32 of the capacitor 34 is
The sawtooth wave is as shown in FIG.

The level control circuit 35 controls the torque command voltage T
I and the voltage S32 are input, and a signal TS obtained by multiplying the voltage S32 by a gain is output to the switch 36 so that the peak of the voltage S32 becomes equal to the torque command voltage TI.
The switch 36 selects either the torque command voltage TI as the first target signal or the signal TS as the second target signal according to the output of the RS flip-flop 37, and the comparator 51 as the signal TP. Output to. The RS flip-flop 37 is set by the reference pulse PI and reset by the output of the comparator 51. Therefore, the switch 36 alternately outputs the signal TI and the signal TS as the signal TP (see FIGS. 3 and 5).

FIG. 5 is a graph showing input / output signals of the logic control circuit 40 and the comparator 51 of FIG. Figure 6
3 is a graph showing a phase current in the motor drive device of FIG. 1. 5 and 6 are enlarged views of the vicinity of t = t1 in FIGS.

The operation of the logic control circuit 40 and the current flowing through the motor 10 will be described with reference to FIGS. 3, 5 and 6. As shown in FIG. 5, the reference pulse PI is a pulse signal having a substantially constant cycle, and this cycle serves as a reference for the PWM control cycle.

RS flip-flop 37 and R of FIG.
The reference pulse PI is input to the set terminals of the S flip-flops 41 and 42. When the reference pulse PI falls, the RS flip-flop 37 is set and the output becomes "H". At this time, the switch 36 selects the torque command voltage TI and outputs it as the signal TP to the comparator 51. Further, since the RS flip-flops 41 and 42 are also set, the control signals F1 and F2 both become "H".

The energized phase switching circuit 23 uses the position signal S21,
It is assumed that it is currently determined to be within the period TU1 of FIG. 2 based on S22 and S23. As shown in FIG. 2, this period TU1 is a period in which the U-phase current I1 is a discharge current having a substantially constant magnitude. In the period TU1, the U-phase current I1 is the only discharge current, so the energized phase switching circuit 23 keeps the drive transistor 1 in the conductive state. Since the V-phase current I2 and the W-phase current I3 are sink currents and need to be changed in magnitude, the energized phase switching circuit 23 controls the control signals F1 and F2.
In accordance with this, the drive transistors 4 and 6 are caused to perform the switching operation. In the period TU1, the energized phase switching circuit 23
Is the drive transistor 4 when the control signal F1 is "H".
Are made conductive, and the drive transistor 6 is made conductive when the control signal F2 is "H". The drive transistors 2, 3, 5 are turned off.

When both the control signals F1 and F2 become "H", the energized phase switching circuit 23 brings the drive transistors 4 and 6 into conduction (first period T1). At this time, a current flows from the drive transistor 1 to the U-phase coil 11 as a discharge current. The current flowing in the U-phase coil 11 is divided into the V-phase coil 12 and the W-phase coil 13, and flows as a sink current toward the drive transistors 4 and 6, respectively.

When the drive transistors 4 and 6 are simultaneously conducting, both the V-phase current I2 and the W-phase current I3 flowing through the V-phase coil 12 and the W-phase coil 13 flow through the current detection resistor 7. The magnitude of the current flowing through the current detection resistor 7 is determined by the U-phase current I flowing through the U-phase coil 11.
Is equal to 1. A voltage proportional to the magnitude of the current flowing through the current detection resistor 7 is generated, and this voltage is input to the negative input terminal of the comparator 51 as the motor current detection signal MC.

Since the U-phase coil 11, the V-phase coil 12 and the W-phase coil 13 are inductive loads, the V-phase current I in the period T1 after the drive transistors 4 and 6 are turned on.
2 and the W-phase current I3 gradually increase (see FIG. 6). Therefore, the motor current detection signal MC also gradually increases.
The voltage of the motor current detection signal MC is the signal TP (see FIG. 5).
When the voltage of 1 is reached, the comparator 51 changes the output CP to "L". Then, the RS flip-flop 41 is reset and the output is inverted to "L", so that the control signal F1
Becomes "L", and the second period T2 starts.

During the period T2, since the control signals F1 and F2 are "L" and "H", respectively, the energized phase switching circuit 23 is provided.
Makes the drive transistor 4 non-conductive. The drive transistor 6 remains conductive. When the drive transistor 4 becomes non-conductive, the source of the drive transistor 3
A regenerative current of the V-phase coil 12 flows through the diode 3D between the drains and the drive transistor 1. The V-phase current I2 that flows as a regenerative current gradually decreases (see FIG. 6). At this time, since only the current flowing in the W-phase coil 13 flows in the current detection resistor 7, the current in the W-phase coil 13 can be detected without being affected by the current in the V-phase coil 12.

After the shift to the period T2, the level of the signal TP input to the positive input terminal of the comparator 51 drops to the potential (bottom level) of the signal TS, but the current of the V-phase coil 12 causes the current detection resistor 7 to pass. When the current stops flowing, the level of the motor current detection signal MC becomes lower and becomes lower than the bottom level of the signal TP, so that the output CP of the comparator 51 returns to "H" again (see FIG. 5).

Further, when the period T2 is entered, the output of the delay circuit 43 is
Following the control signal F1, it becomes "L", and the inverter 44
Output shifts to "H". While the output of the inverter 44 is "L", the output of the NAND gate 46 is "H", and the RS flip-flop 42 outputs the output C of the comparator 51.
It is not reset regardless of the change in P. The RS flip-flop 42 is reset only when the output of the comparator 51 becomes "L" and the output of the inverter 45 becomes "H" after the output of the delay circuit 43 shifts to "L".

During the period T2, since the drive transistors 1 and 6 are still conducting, the current of the W-phase coil 13 continues to increase (see FIG. 6) and the current flowing through the current detection resistor 7 continues to increase. The signal TP output from the phase-based torque signal generator 30 as the voltage of the motor current detection signal MC increases
When the voltage reaches, the comparator 51 sets the output CP to "L". Then, the RS flip-flop 42 is reset, the control signal F2 becomes "L", and the operation proceeds to the period T3.

During the period T3, since the control signals F1 and F2 both become "L", the energized phase switching circuit 23 makes the drive transistors 4 and 6 non-conductive.

As described above, while the control signal F1 is "H", the drive transistor 4 is turned on and the control signal F2 is turned on.
Is high, the drive transistor 6 becomes conductive. Period T1 in which both control signals F1 and F2 are "H"
Is controlled so that the sum of the currents flowing through the V-phase coil 12 and the W-phase coil 13 becomes a value according to the signal TP, and the control signal F1, F2 is "L", "H" during the period T, respectively.
2 is controlled so that the current flowing through the W-phase coil 13 has a value according to the signal TP. That is, the two phases (V phase and W phase) that cause the switching operation in the period TU1.
Among the drive transistors 4 and 6 of the phase), the drive transistor 4 of the phase (V phase) for which the magnitude of the current is to be reduced in the period TU1 is first made non-conductive (see FIG. 2).

During the period T3 when both the control signals F1 and F2 are "L", only the regenerative current is flowing through the coils 11 to 13. The V-phase current I2 and the W-phase current I3 flowing as the regenerative current gradually become smaller (see FIG. 6). When the reference pulse PI is input to the phase-based torque signal generation circuit 30 and the logic control circuit 40, the control signals F1 and F2 are again input.
Becomes "H", and the same process is repeated.

The logic control circuit 40 shown in FIG. 3 may not include the delay circuit 43 when it does not malfunction due to the switching noise of the driving transistors 1 to 6.

FIG. 7 is an explanatory diagram showing a path of a current flowing through the motor 10 in the period T1. As shown in FIG. 7, in the period T1, the V-phase current I2 flowing through the V-phase coil 12
Is from the power supply to the drive transistor 1, the U-phase coil 11, V
The phase coil 12, the drive transistor 4, and the current detection resistor 7 flow in this order. On the other hand, the W-phase current I3 flowing through the W-phase coil 13 is generated by the drive transistor 1, the U-phase coil 1 from the power source.
1, the W-phase coil 13, the drive transistor 6, and the current detection resistor 7 flow in this order. Therefore, the sum of the V-phase current I2 and the W-phase current I3 can be detected from the voltage generated in the current detection resistor 7.

FIG. 8 is an explanatory diagram showing a path of a current flowing through the motor 10 in the period T2. As shown in FIG. 8, during the period T2, the V-phase current I2 flowing through the V-phase coil 12
Is a regenerative current, which flows in a loop in the order of the drive transistor 1, the U-phase coil 11, the V-phase coil 12, and the diode 3D. On the other hand, the W-phase current I flowing through the W-phase coil 13
3 is the same as in FIG. 7 from the power supply to the drive transistors 1 and U.
Phase coil 11, W phase coil 13, drive transistor 6,
And the current detection resistor 7 flow in that order. Therefore, only the W-phase current I3 can be detected from the voltage generated in the current detection resistor 7.

FIG. 9 is an explanatory diagram showing a path of a current flowing through the motor 10 in the period T3. As shown in FIG. 9, in the period T3, the V-phase current I2 flowing through the V-phase coil 12
Is a regenerative current, which flows in a loop like FIG. On the other hand, the W-phase current I3 flowing through the W-phase coil 13 is also a regenerative current, and is the drive transistor 1 and the U-phase coil 1.
1, the W-phase coil 13, and the diode 5D flow in this order in a loop. Therefore, no current flows through the current detection resistor 7. As described above, in the coils 11 to 13, the drive current flowing through the drive transistors of the output circuits of the respective phases is conducted,
Regenerative currents that flow via the diodes of the output circuits of each phase flow alternately.

Next, the operation of the motor drive device of FIG. 1 in the period TU2 of FIG. 2 will be described. As shown in FIG. 2, this period TU2 is a period in which the U-phase current I1 is a sink current having a substantially constant magnitude. Period TU
At 2, the U-phase current I1 is the only sink current, so the energized phase switching circuit 23 keeps the drive transistor 2 conductive. Since the V-phase current I2 and the W-phase current I3 are discharge currents and their magnitudes need to be changed, the energized phase switching circuit 23 causes the drive transistors 3 and 5 to perform a switching operation. Period TU2
In the above, the energized phase switching circuit 23 makes the drive transistor 3 conductive when the control signal F1 is "H" and makes the drive transistor 5 conductive when the control signal F2 is "H". The drive transistors 1, 4, 6 are turned off.

The energized phase switching circuit 23 controls the control signals F1 and F1.
When both 2 become "H", the drive transistors 3 and 5 are turned on. The control signals F1 and F2 are "L",
When it goes to "H", the drive transistor 3 is turned off.
When both the control signals F1 and F2 become "L", the drive transistor 5 is also made non-conductive.

As a result, in the period TU2, the directions in which the U-phase current I1, the V-phase current I2, and the W-phase current I3 flow are opposite to those in the period TU1. Since the other points are similar to the period TU1, detailed description thereof will be omitted.

Periods TV1 and TW of the motor drive device of FIG.
The operation in 1 is the same as that in the period TU1 except for the following points. That is, during the period TV1 in which the V-phase current I2 is a discharge current having a substantially constant magnitude, the energized phase switching circuit 23 continuously turns on the drive transistor 3 instead of the drive transistor 1. Further, the energized phase switching circuit 23 causes the drive transistors 6 and 2 to perform the switching operation in place of the drive transistors 4 and 6, respectively.
The drive transistors 1, 4, 5 are turned off.

During the period TW1 in which the W-phase current I3 is a discharge current having a substantially constant magnitude, the conduction phase switching circuit 2
3 is a drive transistor 5 instead of the drive transistor 1.
Is continuously made conductive. In addition, the energized phase switching circuit 2
3 causes the drive transistors 2 and 4 to perform the switching operation in place of the drive transistors 4 and 6, respectively, so that the drive transistors 1, 3 and 6 are rendered non-conductive.

Period TV2, TW of the motor drive device of FIG.
The operation in 2 is similar to the period TU2 except for the following points. That is, during the period TV2 in which the V-phase current I2 is a sink current having a substantially constant magnitude, the energized phase switching circuit 23 keeps the drive transistor 4 instead of the drive transistor 2 conductive. Further, the energized phase switching circuit 23 causes the drive transistors 5 and 1 to perform the switching operation in place of the drive transistors 3 and 5, respectively.
The drive transistors 2, 3, 6 are turned off.

During the period TW2 in which the W-phase current I3 is a sink current having a substantially constant magnitude, the energized phase switching circuit 2
3 is a drive transistor 6 instead of the drive transistor 2.
Is continuously made conductive. In addition, the energized phase switching circuit 2
3 causes the drive transistors 1 and 3 to perform the switching operation in place of the drive transistors 3 and 5, respectively, so that the drive transistors 2, 4 and 5 are turned off.

FIG. 10 is a block diagram showing another example of the configuration of the logic control circuit of FIG. The logic control circuit 140 of FIG. 10 is the logic control circuit 40 further including a delay circuit 47. The reference pulse PI is input to the delay circuit 47. The delay circuit 47 delays the input reference pulse PI by a predetermined time and then RS
It outputs to the set input of the flip-flop 42.

Instead of the logic control circuit 40 of FIG.
When the logic control circuit 140 of 0 is used, the RS flip-flop 41 is set and the control signal F1 changes to “H”, and after a predetermined time has elapsed, the RS flip-flop 42 is set and the control signal F2 is set to “H”. Change to H ". In this way, the control signals F1 and F2 are simultaneously "L".
Does not change from "H" to "H".

For example, in the period TU1, the drive transistor 6 is turned on after a predetermined period has elapsed since the drive transistor 4 was turned on first and the V-phase current I2 started to flow.
The phase current I3 begins to flow. Therefore, it is possible to avoid a situation in which switching noise generated when two-phase currents start flowing at the same time is superimposed on the ground line and the voltage of the current detection resistor 7 has already exceeded the target value. Also, RS
It is possible to reduce the possibility that the flip-flop 42 malfunctions due to the switching noise of the drive transistor. The delay circuit 47 is not always necessary if measures are taken such as reducing the wiring resistance of the ground line.

As described above, according to the motor drive device of the present embodiment, the motor 10 is configured so as to have a substantially trapezoidal waveform having an amplitude according to the torque command voltage TI as shown in FIG.
Since the phase currents I1 to I3 can be controlled, the change in the phase current at the time of switching the energized phase can be moderated.

When PWM control of three-phase currents is required, normally three current detection resistors are required. But,
The motor drive device of the present embodiment can control three-phase currents using one current detection resistor, and enables PWM control in which the magnitudes of phase currents do not vary. Since the number of current detection resistors is small, the scale of the device can be reduced.

(Second Embodiment) FIG. 11 is a block diagram of a motor drive device according to a second embodiment of the present invention. The motor drive device of FIG. 11 is different from the motor drive device of FIG. 1 in that the phase-specific torque signal generation circuit 30, the logic control circuit 40, and the comparator 51 are replaced with a phase-specific torque signal generation circuit 230 and a logic control circuit. The circuit 240, the first comparator 52, and the second comparator 53 are provided. The other components are the same as those described in the first embodiment, so the same reference numerals are given and the description thereof is omitted. A phase-specific torque signal generation circuit 230,
The logic control circuit 240 and the comparators 52 and 53 form the energization period control unit 200.

In FIG. 11, the phase-specific torque signal generation circuit 230 is similar to the phase-specific torque signal generation circuit 30 in FIG. 3, and based on the position signal PS and the torque command voltage TI, the current flowing through the current detection resistor 7 is increased. The signal TS indicating the voltage corresponding to the target value of is generated. Further, the phase-based torque signal generation circuit 230 outputs the torque command voltage TI and the signal TS to the positive input terminals of the comparators 52 and 53, respectively. The torque command voltage TI may be input to the comparator 52 without passing through the phase-specific torque signal generation circuit 230.

At the negative input terminals of the comparators 52 and 53, the voltage generated in the current detection resistor 7 (driving transistors 2, 4, 6
Source potential) is input as the motor current detection signal MC. The comparators 52 and 53 have respective output CPs.
1, CP2 are output to the logic control circuit 240.
Further, the reference pulse PI is input to the logic control circuit 240. The logic control circuit 240 generates the switching operation control signals F1 and F2 that define the period in which the drive transistors 1 to 6 are made conductive, and the energized phase switching circuit 23.
Output to.

FIG. 12 shows the energization period control section 200 of FIG.
3 is a block diagram showing an example of the configuration of FIG. Energization period control unit 2
00 includes a phase-based torque signal generation circuit 230, a logic control circuit 240, and comparators 52 and 53. The phase-specific torque signal generation circuit 230 of FIG. 12 includes a double-edge differentiation circuit 31, a constant current source 32, a switch 33, a capacitor 34, and a level control circuit 35. The phase-specific torque signal generation circuit 230 outputs the torque command voltage TI and the output TS of the level control circuit 35 shown in FIG. 4 to the comparators 52 and 53 as they are, except that the phase-specific torque signal generation circuit of FIG. It is similar to the circuit 30.

The logic control circuit 240 of FIG.
, An RS flip-flop 41 as a second latch, an RS flip-flop 42 as a second latch, inverters 44 and 45, and a NAND gate 46.
The inverters 44 and 45 and the NAND gate 46 operate as a logic circuit 49.

The operation of the logic control circuit 240 and the current flowing through the motor 10 will be described with reference to FIGS. The reference pulse PI is input to the set terminals of the RS flip-flops 41 and 42 in FIG. When the reference pulse PI falls, the RS flip-flop 4
Since 1 and 42 are set, the control signals F1 and F2 are both "H". When the control signal F1 is "H",
Since the output of the inverter 44 is "L" and the output of the NAND gate 46 is "H", the RS flip-flop 42 is not reset regardless of the level of the output CP2 of the comparator 53.

At present, it is assumed that the period TU1 shown in FIG.
When both the control signals F1 and F2 become “H”, the energized phase switching circuit 23 makes the drive transistors 4 and 6 conductive (first period T1) and the V-phase coil 12 and the W-phase coil 13 respectively flow. Both the current I2 and the W-phase current I3 flow through the current detection resistor 7. A voltage proportional to the magnitude of the current flowing through the current detection resistor 7 is generated, and this voltage is input to the negative input terminals of the comparators 52 and 53 as the motor current detection signal MC.

When the motor current detection signal MC gradually rises and the voltage of the motor current detection signal MC reaches the voltage of the signal TI, the comparator 52 changes the output CP1 to "L". Then, the RS flip-flop 41 is reset and changes its output to "L", so that the control signal F1
Becomes "L". Then, since the output of the inverter 44 becomes "H", the RS flip-flop 42 is reset according to the level change of the output CP2 of the comparator 53.

The control signals F1 and F2 are "L",
Since it becomes “H”, the energized phase switching circuit 23 makes the drive transistor 4 non-conductive. The drive transistor 6 remains conductive (second period T2). At this time, only the current flowing in the W-phase coil 13 flows in the current detection resistor 7, so that the current W in the V-phase coil 12 is not affected.
The current of the phase coil 13 can be detected.

Since the drive transistors 1 and 6 are still conducting, the current of the W-phase coil 13 continues to increase and the current flowing through the current detection resistor 7 continues to increase. When the voltage of the motor current detection signal MC reaches the voltage of the signal TS output from the phase-specific torque signal generation circuit 230, the comparator 53 sets the output CP2 to "L". Then, the NAND gate 46
Goes to "L", the RS flip-flop 42 is reset, and the control signal F2 goes to "L".

Since the control signals F1 and F2 both become "L", the energized phase switching circuit 23 also makes the drive transistor 6 nonconductive (period T3).

As described above, the motor drive device shown in FIG.
The motor 10 can be driven similarly to the motor drive device of FIG. The motor drive device of FIG. 11 includes a comparator 52,
Since 53 does not easily malfunction, stable operation can be performed.

In the above embodiments, the motor drive device has been described as including the diodes 1D to 6D.
Alternatively, each of the drive transistors 1 to 6 may include a parasitic diode. That is, a diode may structurally exist in each of the drive transistors 1 to 6.

The drive transistors 1 to 6 are n-type M-type.
It may be a transistor other than the OS transistor.

Further, the lower-arm side drive transistor 2,
Although the case where the current detection resistor 7 is provided between the sources of 4, 6 and the ground has been described, even if the current detection resistor 7 is provided between the power supply VCC and the drains of the upper arm side drive transistors 1, 3, 5. Good.

Also, an example has been described in which the motor 10 is controlled in units of a period corresponding to one obtained by dividing the electrical angle of 360 ° into six. However, for example, the period may be divided into twelve and the energized phase may be switched for each shorter period.

Although the motor connection has been described as a Y connection, it may be a delta connection.

Further, among the two-phase driving transistors for performing the switching operation, the example in which the driving transistor of the phase for which the magnitude of the current should be reduced is made non-conducting is explained first, but it rises sharply and rises gently. By using the falling sawtooth wave signal TS, the same operation can be performed even if the drive transistor of the phase in which the magnitude of the current is to be increased is first made non-conductive.

Further, the case where the phases of the phase currents of the three phases are the U phase, the V phase, and the W phase in order from the leading phase has been described, but in order to reverse the motor, the W phase, the V phase, and the U phase. The same applies when the order of phases is set.

Although the case of driving a three-phase motor has been described, the same applies to the case of driving a four-phase motor or more.

Further, although the case where the position detection is performed by using the hall element has been described, the hall element does not necessarily have to be used. For example, CR for each U-phase, V-phase, and W-phase
The position of the motor rotor can be detected by providing a filter circuit, filtering the harmonic components of the PWM drive current, and comparing the filter output and the midpoint potential of the motor coil for each phase. However, considering the malfunction caused by the harmonic component of the PWM drive current, it is more advantageous to use the Hall element.

[0102]

According to the motor drive device of the present invention, it is possible to prevent the phase current from changing abruptly, so that it is possible to suppress the occurrence of motor vibration and noise during phase switching. Since only one current detection resistor, which is usually required to control a plurality of phases of current, is used, the scale of the device can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram of a motor drive device according to a first embodiment of the present invention.

FIG. 2 is a graph showing a target waveform of each phase current of a motor.

FIG. 3 is a block diagram showing an example of a configuration of an energization period control unit in FIG.

FIG. 4 is a graph showing signals relating to a position detection circuit and a phase-specific torque signal generation circuit.

5 is a graph showing input / output signals of the logic control circuit and the comparator of FIG.

6 is a graph showing a phase current in the motor drive device of FIG.

FIG. 7 is an explanatory diagram showing a path of a current flowing through the motor in a period T1.

FIG. 8 is an explanatory diagram showing a path of a current flowing through a motor in a period T2.

FIG. 9 is an explanatory diagram showing a path of a current flowing through the motor in a period T3.

10 is a block diagram showing another example of the configuration of the logic control circuit of FIG.

FIG. 11 is a block diagram of a motor drive device according to a second embodiment of the present invention.

FIG. 12 is a block diagram showing an example of a configuration of an energization period control unit in FIG.

FIG. 13 is a block diagram of a conventional peak current detection type motor drive device.

14 is a graph showing changes in phase currents of a motor driven by the motor drive device of FIG. 13 with respect to time.

15 is a graph showing the current detection resistance voltage and the phase currents of the V-phase and the W-phase near time t = tz in FIG. 14 with the time axis enlarged.

[Explanation of symbols]

1-3 Upper arm side drive transistor (upper arm side switching element) 4-6 Lower arm side drive transistor (lower arm side switching element) 1D to 6D Diode 7 Current detection resistor 10 Motor 11 U-phase coil 12 V-phase coil 13 W Phase coil 21 Hall element circuit 22 Position detection circuit 23 Energized phase switching circuit 24 Pre-drive circuit 30, 230 Phase-specific torque signal generation circuit 40, 140, 240 Logic control circuit 41 RS flip-flop (first latch) 42 RS flip-flop (Second latch) 43, 47 Delay circuit 49 Logic circuit 51 Comparator 52 First comparator 53 Second comparator 100, 200 Energization period control unit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasunaga Yamamoto             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Masashi Inao             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Taishi Iwanaga             1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Sith             Tem Techno Co., Ltd. F term (reference) 5H560 BB04 BB07 DA02 DA19 DC12                       EB01 RR01 SS01 TT04 TT06                       TT07 UA02 XA02 XA12

Claims (10)

[Claims] 1. A plurality of output circuits each having an upper arm side switching element and a lower arm side switching element connected in series are provided, and the upper arm side switching element and the lower arm side switching element in each of the output circuits are connected. A motor drive device for supplying a current to a motor from a point, which is connected in series with the plurality of output circuits and commonly,
Any one of the plurality of output circuits, a current detection resistor for detecting a current supplied to the plurality of output circuits, a position detection unit that outputs a position signal according to the position of the rotor of the motor, One of the switching elements is selected according to the position signal, and is made conductive during a period corresponding to a predetermined electrical angle,
When the switching element to be conducted is the upper arm side switching element, the lower arm side switching element in the remaining one of the plurality of output circuits is caused to perform the switching operation, and the switching element to be conducted is the lower arm side switching element. In some cases, in each of the energized phase switching circuit that causes the upper arm side switching element in any one of the remaining ones of the plurality of output circuits to perform a switching operation, and the plurality of periods in which a period corresponding to the predetermined electrical angle is divided. A second period in which any one of the plurality of switching elements that are conducted during the switching operation is continuously conducted and a first period in which a plurality of switching elements are conducted is second Of the input torque command signal so that And a voltage generated in the current detection resistor, a motor drive device including a current-supply period control unit that generates and outputs a switching-operation control signal that controls the switching operation of the current-carrying phase switching circuit. 2. The motor drive device according to claim 1, wherein the energization period control unit corresponds to a target value of a current to be passed through the current detection resistor in the first period, which corresponds to the torque command signal. And the second target signal corresponding to the target value of the current to be passed through the current detection resistor in the second period, which is obtained according to the torque command signal and the position signal. A phase-dependent torque signal generation circuit for outputting to, a comparator that determines whether the voltage generated in the current detection resistor exceeds the output of the phase-dependent torque signal generation circuit, and outputs the result, the switching operation A logic control circuit that generates and outputs the switching operation control signal according to a reference pulse defining the cycle of the output of the comparator and the comparator, the logic control circuit, When the comparator determines that the voltage generated in the current detection resistor exceeds the output of the phase-specific torque signal generation circuit for the first period, the first period is ended,
When it is determined that the voltage generated in the current detection resistor exceeds the output of the phase-based torque signal generation circuit for the second period, the switching operation control signal is generated so as to end the second period. The motor drive device is characterized in that 3. The motor drive device according to claim 2, wherein the logic control circuit is set by the reference pulse, and is set by the reference pulse, a first latch that uses the output of the comparator as a reset input. A second latch, a logic circuit that receives the output of the first latch and the output of the comparator as input, and applies the obtained output to the second latch as a reset input. 1st and 2nd
The output of the latch is output as the switching operation control signal, and the output of the comparator of the first latch is such that the voltage generated in the current detection resistor exceeds the first target signal. Is reset, the logic circuit outputs the output of the first latch and the logic circuit outputs the output of the comparator when the output of the first latch is reset. And outputs the output of the comparator when the first latch is not reset, and the second latch outputs the output of the comparator by the logic circuit. And
The motor drive device is reset when the output of the comparator indicates that the voltage generated in the current detection resistor exceeds the second target signal. 4. The motor drive device according to claim 3, wherein the logic control circuit further includes a delay circuit that delays an output of the first latch by a predetermined time and outputs the delayed output. 2. The motor drive device according to claim 1, wherein the output of the latch is applied to the logic circuit via the delay circuit. 5. The motor drive device according to claim 1, wherein the energization period control unit responds to a target value of a current to be passed through the current detection resistor in the first period according to the torque command signal. And a second target signal corresponding to a target value of a current to be passed through the current detection resistor in the second period, which is obtained according to the torque command signal and the position signal. A phase-dependent torque signal generation circuit, a first comparator that determines whether or not the voltage generated in the current detection resistor exceeds the first target signal, and outputs the result, and the current detection resistor A second comparator that determines whether the generated voltage exceeds the second target signal and outputs the result, a reference pulse that defines the cycle of the switching operation, and the first and second Comparator A logic control circuit that generates and outputs the switching operation control signal according to a force, wherein the first comparator is configured such that the voltage generated in the current detection resistor is the first target. When it is determined that the signal is exceeded, the first period is ended, and when the second comparator determines that the voltage generated in the current detection resistor exceeds the second target signal, the first comparator is terminated. A motor drive device, wherein the switching operation control signal is generated and output so as to end the period of 2. 6. The motor drive device according to claim 5, wherein the logic control circuit includes a first latch that is set by the reference pulse and that uses the output of the first comparator as a reset input. A logic circuit having a second latch set by a pulse, an output of the first latch and an output of the second comparator as inputs, and providing the obtained output as a reset input to the second latch. And outputting the outputs of the first and second latches as the switching operation control signal, wherein the first latch outputs the output of the first comparator to the current detection resistor. The logic circuit is reset when the voltage indicates that the voltage exceeds the first target signal, and the logic circuit outputs the output of the first latch to the first latch. Outputs the output of the second comparator when indicating that it is reset, and outputs the output of the second comparator when indicating that the first latch is not reset In the second latch, the logic circuit outputs the output of the second comparator, and the output of the second comparator is the voltage generated in the current detection resistor. A motor drive device, which is reset when it indicates that the target signal of 2 is exceeded. 7. The motor drive device according to claim 2, wherein the reference pulse has a substantially constant cycle. 8. The motor drive device according to claim 2, wherein the phase-specific torque signal generation circuit uses a voltage corresponding to the torque command signal as the first target signal, and outputs the position signal and the position signal. Based on the first target signal, a sawtooth wave whose period is a period corresponding to the predetermined electrical angle and whose peak value is substantially equal to the first target signal is generated as the second target signal. A motor drive device characterized by being used. 9. The motor drive device according to claim 1, wherein the energization period control unit selects one of a plurality of switching elements that conducts in the first period from one that conducts in the second period. A motor for generating a signal for controlling a switching operation so as to be non-conductive until a predetermined time elapses from the start of the first period and outputting the signal as the switching operation control signal. Drive. 10. A plurality of output circuits each having an upper arm side switching element and a lower arm side switching element connected in series are provided, and the plurality of output circuits are connected in series and commonly to the plurality of output circuits. A motor drive device comprising a current detection resistor for detecting a current supplied to an output circuit, and supplying current to a motor from a connection point between an upper arm side switching element and a lower arm side switching element in each of the output circuits. A step of obtaining a position signal according to the position of the rotor of the motor, and one switching element in any one of the plurality of output circuits is selected according to the position signal so as to correspond to a predetermined electrical angle. And the switching element to be conducted is the upper arm side switching element. In the case where any one of the remaining output circuits of the plurality of output circuits is a lower arm side switching element, the lower arm side switching element in any of the plurality of output circuits is caused to perform a switching operation and is brought into conduction. A step of causing a plurality of upper arm side switching elements to perform a switching operation, wherein in the step of performing the switching operation, the switching operation is performed in each of a plurality of periods in which a period corresponding to the predetermined electrical angle is divided. Among the switching elements, there is a first period in which a plurality of switching elements are conducted, and a second period in which any one of the plurality of switching elements conducted during the first period is continuously conducted. As described above, the input torque command signal and the current detection resistance are Motor driving method which controls the switching operation according to a voltage occurring.