JP2009100526A - Motor control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control the rotation, over a wide range starting from a low-rotation region, such as locking torque range to a high-rotation region, using a simple device configuration. <P>SOLUTION: A motor controller 4 includes OR circuits 31WH to 31UL, and AND circuits 32WH to 32UL that receive output signals of three Hall sensors 3U, 3V, 3W which are respectively disposed, in correspondence with the coils U, V, W of a brushless motor 1 and an output signal of a timing generation unit 21 and perform logical operations, and the outputs of the individual AND-circuits 32WH to 32UL are connected to the individual switching elements UH to WL of an inverter circuit 6 on a one-to-one basis. The timing generation unit 21 change over the output signals so that energization can be switched between 180°-energization and 120°-energization, between low-speed rotation and high-speed rotation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a motor control device that performs drive control of a brushless motor.

In the DC brushless motor, energy saving and noise reduction are achieved by controlling the timing for switching the current flowing through the coil to be optimal. As a conventional method for optimizing the switching timing, for example, there is one disclosed in Patent Document 1. This brushless motor has a Hall IC that detects the direction of the magnetic field of the sensor magnet that rotates integrally with the rotor, and calculates the rotation speed of the motor from the period in which the change in the direction of the magnetic field is detected. Furthermore, the timing control means calculates the advance amount according to the rotational speed, performs advance control according to the advance amount from the advance amount and the sensor signal, and turns on and off the FET (field effect transistor). It was.
JP 2000-134978 A

However, in order to calculate the amount of advance according to the rotation speed, complicated calculation processing is required, and an expensive microcomputer or the like is required.
The present invention has been made in view of such circumstances, and is mainly intended to enable rotation control in a wide range from a low rotation region such as a lock torque region to a high rotation region with a simple device configuration. Objective.

The invention according to claim 1 of the present invention that solves the above problem is capable of switching a current flowing through the coil in a motor control device that controls the rotation of a rotor by controlling energization of a three-phase coil of a brushless motor. A plurality of switching elements arranged on the coil, a plurality of sensors provided corresponding to each of the coils, and detecting the rotational position of the rotor, and switching the switching elements based on output signals of the plurality of sensors. A control unit that generates a drive signal, and the control unit includes a switching control unit that switches between 120 ° energization having an energization suspension period and 180 ° energization having no energization suspension period. The device.
In this motor control apparatus, a mode in which 180 ° energization is performed based on the output of the sensor and a mode in which 120 ° energization is performed by correcting the advance angle of the same sensor output can be selected.

According to a second aspect of the present invention, in the motor control device according to the first aspect, the switching control unit is configured to perform 180 ° energization when starting the brushless motor and then switch to 120 ° energization. It is characterized by.
In this motor control device, 180 ° energization is performed during low-speed rotation, and 120 ° energization is performed with an advance correction during high-speed rotation.

According to a third aspect of the present invention, in the motor control device according to the first or second aspect, the switching control unit is configured to switch between 120 ° energization and 180 ° energization depending on the rotation speed of the brushless motor. It is characterized by.
In this motor control device, the rotational speed of the brushless motor is checked, and when the rotational speed reaches a preset rotational speed, the switching control unit outputs a signal for switching from 180 ° energization to 120 ° energization.

According to a fourth aspect of the present invention, in the motor control device according to the first or second aspect, the switching control unit switches between 120 ° energization and 180 ° energization in an elapsed time from the start of the brushless motor. It is characterized by comprising.
In this motor control device, the elapsed time from the start of starting is checked, and when a preset time has elapsed, the switching control unit outputs a signal for switching from 180 ° energization to 120 ° energization.

According to a fifth aspect of the present invention, in the motor control device according to any one of the first to fourth aspects, the control unit includes an output of the switching unit and an output or output of any one of the sensors. An AND circuit to which an inverted signal is input, and an AND circuit to which an output of the OR circuit and an output of the other sensor or an inverted signal of the sensor are input, An output is connected to the switching element.
This motor control device realizes processing for switching between 180 ° energization and 120 ° energization according to the output of the switching control unit and processing for switching energization timing in each energization mode by a combination of an AND circuit and an OR circuit.

  According to the present invention, by switching between 120 ° energization and 180 ° energization, it is possible to select an optimum energization mode according to the rotational speed and load state with a simple configuration. The brushless motor can be efficiently rotated.

The best mode for carrying out the invention will be described in detail with reference to the drawings.
FIG. 1 shows the configuration of a brushless motor and a motor control device. The brushless motor 1 has a stator having three-phase coils U, V, and W, and a rotor having a permanent magnet for a field, and a sensor magnet 2 that rotates together with the rotor is attached to a rotating shaft of the rotor. ing. The sensor magnet 2 is alternately magnetized with S poles and N poles in the rotational direction, and in the vicinity of the sensor magnet 2, three Hall sensors 3U, 3V, 3W for detecting the rotational position are 120 ° in the rotational direction. It is attached so that switching of the magnetic poles of the sensor magnet 2 can be detected at intervals of.

The motor control device 4 includes an inverter circuit 6 that switches a current flowing from the DC power supply 5 to the coils U, V, and W, and a switching control unit that receives the outputs of the hall sensors 3U, 3V, and 3W and performs switching of the inverter circuit 6. 7.
In the inverter circuit 6, three arms 11, 12, and 13 are connected in parallel to the DC power supply 5. In the first arm 11, the midpoint between the two switching elements WH and WL is connected to the coil W. In the second arm 12, the midpoint of the two switching elements VH and VL is connected to the coil V. In the third arm 13, the midpoint of the two switching elements UH and UL is connected to the coil U. The coils U, V, and W are, for example, star-connected, and the ends of the coils U, V, and W on the side opposite to the intersection side are electrically connected to the inverter circuit 6, respectively. In addition, a current sensor may be provided on a conduction line that connects the inverter circuit 6 and the coils U, V, and W so that the current flowing through the coils U, V, and W can be monitored. It is possible to monitor the coils U, V, and W so that no overcurrent flows.

  The control unit 7 includes a timing generation unit 21 that is a switching control unit and a switching circuit 22. The switching circuit 22 includes six OR circuits 31UH, 31UL, and 31VH created using converters 30U, 30V, and 30W that convert signals from the hall sensors 3U, 3V, and 3W, CMOS (Complementary Metal-Oxide Semiconductor), and the like. , 31VL, 31WH, 31WL and six AND circuits 32UH, 32UL, 32VH, 32VL, 32WH, 32WL for outputting drive signals to the inverter circuit 6.

The output of the W-phase Hall sensor 3W and the output of the OR circuit 31WH are connected to the input of the AND circuit 32WH. The output of the AND circuit 32WL is connected to the switching element WH on the H (High) side of the first arm 11 via a buffer. The output of the converter 30U that inverts the signal of the U-phase Hall sensor 3U and the output of the timing generator 21 are connected to the input of the OR circuit 31WH.
The input of the AND circuit 32WL is connected to the output of the converter 30W for inverting the signal of the W-phase Hall sensor 3W and the output of the OR circuit 31WL. The output of the AND circuit 32WL is connected to the switching element WL on the L (Low) side of the first arm 11. The output of the U-phase Hall sensor 3U and the output of the timing generator 21 are connected to the input of the OR circuit 31WL.

The output of the V-phase hall sensor 3V and the output of the OR circuit 31VH are connected to the input of the AND circuit 32VH. The output of the AND circuit 32VH is connected to the switching element VH on the H side of the second arm 12. The output of the converter 30W for inverting the signal of the W-phase Hall sensor 3W and the output of the timing generator 21 are connected to the input of the OR circuit 31VH.
The input of the AND circuit 32VL is connected to the output of the converter 30V for inverting the signal of the V-phase Hall sensor 3V and the output of the OR circuit 31VL. The output of the AND circuit 32VL is connected to the switching element VL on the L side of the second arm 12. The output of the W-phase Hall sensor 3W and the output of the timing generator 21 are connected to the input of the OR circuit 31VL.

The output of the U-phase hall sensor 3U and the output of the OR circuit 31UH are connected to the input of the AND circuit 32UH. The output of the AND circuit 32UH is connected to the switching element UH on the H side of the third arm 13. The output of the converter 30V for inverting the signal of the V-phase Hall sensor 3V and the output of the timing generator 21 are connected to the input of the OR circuit 31UH.
The output of the converter 30U that inverts the signal of the U-phase Hall sensor 3U and the output of the OR circuit 31UL are connected to the input of the AND circuit 32UL. The output of the AND circuit 32UL is connected to the switching element UL on the L side of the third arm 13. The output of the V-phase hall sensor 3V and the output of the timing generator 21 are connected to the input of the OR circuit 31UL.

  The timing generation unit 21 switches between an H level signal and an L level signal according to the rotation speed of the brushless motor 1 and outputs the signal. As will be described later, when the timing generator 21 outputs an H level signal, 180 ° energization is performed. When an L level signal is output, 120 ° energization occurs. The switching of the signal level may be performed, for example, by monitoring the rotation speed of the brushless motor 1 and when the rotation speed reaches a predetermined rotation speed. When the rotation speed of the brushless motor 1 changes, the frequency of the pulse signal of the Hall sensor output changes in proportion to this, so if an FV converter that converts the signal to a DC voltage is used at this frequency, the rotation of the brushless motor 1 The signal level can be switched by a number. The rotation speed serving as a threshold value for switching the signal level is the rotation speed at which the 120 ° energization causes the rotation more efficiently, and is determined by the load applied to the brushless motor 1 and the motor standard.

The operation of this embodiment will be described.
When starting the brushless motor 1, since the rotation speed is zero, the timing generator 21 outputs an H level signal. As shown in FIG. 2, the output of each Hall sensor 3U, 3V, 3W is sequentially switched between the H level and the L level, as shown in FIG. For example, the U-phase Hall sensor 3U is at the H level until time t3, thereafter becomes the L level, and switches to the H level again at time t6. The time axis is one period from t0 to t6, and three sections (for example, time t0 to time t3) correspond to 180 °.

Here, how the energization is switched in accordance with the rotation of the rotor will be described by taking the period from time t0 to time t2 during low-speed rotation as an example.
From time t0 to time t1, the hall sensor 3U is at the H level, the hall sensor 3V is at the L level, and the hall sensor 3W is at the H level. As a result, in the OR circuit 31WH of FIG. 1, the output of the converter 30U and the H level signal of the timing generator 21 are input. Since converter 30U inverts the signal from hall sensor 3U, it outputs an L level signal. As a result, since an L level signal and an H level signal are output to the OR circuit 31WH, an H level signal is output.
The AND circuit 32WH receives the H level signal output from the OR circuit 31WH and the H level signal from the Hall sensor 3W, and outputs an H level signal. As a result, the switching element WH is turned ON (H level). Similarly, the switching elements UH, VL are turned on, and the other switching elements UL, VH, WL are turned off (L level). As a result, current flows from each of the U phase and the W phase toward the V phase, and the rotor is rotated.

  From time t1 to time t2, the hall sensor 3U is at the H level, the hall sensor 3V is at the L level, and the hall sensor 3W is at the L level. Since the timing generator 21 maintains the H level signal, the switching elements UH, VL, and WL are turned on, and the switching elements UL, VH, and WH are turned off. As a result, current flows from the U phase to each of the V phase and the W phase, and the rotor is further rotated.

  In this way, for example, the switching element UH is turned on from time t1 to time t3. The switching element UL is turned on from time t4 to time t6. As a result, the current flows in the coil U in the direction from the time t0 to the time t3 toward the intersection of the coils, and the current flows in the opposite direction from the time t3 to the time t6 (= t0). In the 180 ° energization, current always flows through each of the three coils U, V, and W, and the energization is performed without any rest period. In one coil, the direction of current changes every 180 °.

Next, the energization pattern at the time of forward high rotation will be described. During normal high rotation, the timing generator 21 outputs an L level signal.
As shown in FIG. 3, from time t0 to time t1, the hall sensor 3U is at the H level, the hall sensor 3V is at the L level, and the hall sensor 3W is at the H level. The L level signal generated by the converter 30U and the L level signal from the timing generator 21 are input to the OR circuit 31WH in FIG. 1, and the L level signal is output. The AND circuit 32WH receives an L level signal from the OR circuit 31WH and an L level signal from the Hall sensor 3W. As a result, an L level signal is output from the AND circuit 32WH, and the switching element WH is turned OFF. Similarly, the switching elements UL, VH, WL are turned off, and the remaining two switching elements UH and switching element VL are turned on. As a result, a current flows from the coil U toward the coil V, and the rotor is rotated. No current flows through the coil W.

From time t1 to time t2, only the switching element UH and the switching element WL are turned on, and the other switching elements UL, VH, VL, and WH are turned off. A current flows from the coil U toward the coil W. No current flows through the coil V.
From time t2 to time t3, only the switching element VH and the switching element WL are turned on, and the other switching elements UH, UL, VL, and WH are turned off. A current flows from the coil V toward the coil W. No current flows through the coil U.
From time t3 to time t4, only the switching element UL and the switching element VH are turned on, and the other switching elements UH, VL, WH, and WL are turned off. A current flows from the coil V toward the coil U. No current flows through the coil W.

  Thus, for example, current flows through the coil U from time t0 to time t2. Between the time t2 and the time t3, there is a rest period in which no current flows. Between time t3 and time t5, current flows in the opposite direction. Between the time t5 and the time t6, it becomes a rest period again. In the 120 ° energization, energization control is performed so that a current flows through any two of the three coils U, V, and W and no current flows through the remaining one coil.

FIG. 4 shows the difference in the waveform of the applied voltage between 120 ° energization and 180 ° energization taking the U phase as an example. The output of the hall sensor 3U is the same in any energization method, but the switching timings of the switching elements UH and UL are different. As a result, the center of the waveform applied voltage at 120 ° energization is advanced by 30 ° with respect to the center (wavefront, wave bottom) of the waveform applied voltage at 180 ° energization. That is, by switching from 180 ° energization to 120 ° energization, the control is equivalent to the case where 30 ° advance angle control is performed.

Further, FIG. 5 shows a graph of the current value and the number of rotations from the start to the target number of rotations. The horizontal axis indicates time, and the vertical axis indicates the rotation speed and current value. In this graph, it is assumed that the predetermined rotational speed is reached at time t11 and the timing generation unit 21 switches the signal level.
As indicated by line L1, the rotational speed gradually increases and reaches the desired rotational speed. As shown in the line L2, a large current flows by energizing 180 ° until the time t11. At the time t11, when the current is shifted to 120 ° energization, the current value decreases and becomes substantially constant.

  As a comparative example, the line L3 shows the change in the number of rotations in the conventional method of controlling rotation by only 120 ° energization, and the line L4 shows the change in the current value in the conventional method. The current value shown in the line L4 changes with a smaller value than 180 ° energization. The time required to reach the desired rotational speed at the rotational speed indicated by the line L3 is longer than that in this embodiment.

In this embodiment, the 180 ° energization is performed at the start, and then the transition to the 120 ° energization is performed, so that a sufficient torque can be obtained even in a low rotation range. Since 120 ° energization, that is, 30 ° advance angle control can be performed in the high rotation range, efficient operation is possible even in the high rotation range. Furthermore, as shown in FIG. 5, the time required to reach the desired rotational speed can be shortened compared to the conventional method.
Since it is possible to control the rotation in a wide area simply by switching the logic of 180 ° energization and 120 ° energization, the configuration of the motor control device 4 can be simplified and the cost can be reduced.
Since the timing of switching the energization is controlled by the motor rotation speed, efficient operation is possible. For example, when decelerating from a high rotation range to a low rotation range, it is possible to switch from 120 ° energization to 180 ° energization.

Note that the present invention can be widely applied without being limited to the above-described embodiment.
For example, the timing generator 21 may be a timer. When a certain amount of time has elapsed after startup, it is possible to switch from 180 ° energization to 120 ° energization.

1 is a block diagram of a system including a motor control device according to an embodiment of the present invention. It is a timing chart of the energization control at the time of forward rotation low speed rotation. It is a timing chart of the energization control at the time of forward rotation high speed rotation. It is a figure explaining the difference between 180 degrees energization and 120 degrees energization taking the U phase coil as an example. It is a graph which shows an example of the relationship between the rotation speed at the time of a start, and an electric current, and is a graph which displayed the relationship between the rotation speed at the time of a conventional start-up, and an electric current as a comparison.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Brushless motor 3U, 3V, 3W Hall sensor 4 Motor control apparatus 6 Inverter circuit 21 Timing generation part (switching control part)
31UH, 31UL, 31VH, 31VL, 31WH, 31WL OR circuit 32UH, 32UL, 32VH, 32VL, 32WH, 32WL AND circuit U, V, W Coil UH, UL, VH, VL, WH, WL Switching element

Claims (5)

In a motor control device that performs energization control on a three-phase coil of a brushless motor and performs rotation control of the rotor,
A plurality of switching elements arranged to be able to switch the current flowing through the coil;
A plurality of sensors provided corresponding to each of the coils and detecting the rotational position of the rotor;
A control unit that generates a drive signal for switching the switching element based on output signals of the plurality of sensors,
The control unit includes a switching control unit that switches between 120 ° energization having an energization stop period and 180 ° energization having no energization stop period.   2. The motor control device according to claim 1, wherein the switching control unit is configured to perform 180 ° energization when the brushless motor is started and then switch to 120 ° energization. 3.   3. The motor control device according to claim 1, wherein the switching control unit is configured to switch between 120 ° energization and 180 ° energization depending on a rotation speed of the brushless motor.   3. The motor control device according to claim 1, wherein the switching control unit is configured to switch the 120 ° energization and the 180 ° energization with an elapsed time from the start of the start of the brushless motor.   The control unit includes an OR circuit to which an output of the switching unit and an output of any one of the sensors or a signal obtained by inverting the output are input, an output of the OR circuit, and an output of the other one of the sensors Or an AND circuit to which a signal obtained by inverting the output is input, and an output of the AND circuit is connected to the switching element. The motor control apparatus described.

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