JP5314103B2 - Permanent magnet synchronous motor drive device - Google Patents

Description

  Embodiments described herein relate generally to a sensorless drive permanent magnet synchronous motor drive device.

  2. Description of the Related Art A variable speed motor driving device that drives an electric motor at a variable speed using an inverter is applied to various fields. Among the electric motors, the permanent magnet synchronous motor has been widely adopted because it has a permanent magnet in the rotor and is more efficient than the induction motor. Further, position / speed sensorless control without using a speed sensor or position sensor is useful in terms of improving reliability and improving constraints on the installation environment.

  In order to enhance the practicality of such an electric motor drive device, means for detecting an open phase between the electric motor drive device and the electric motor has been proposed (see, for example, Patent Documents 1 and 2). However, in the case of phase loss determination for a permanent magnet synchronous motor, since a magnetic flux exists in the rotor, torque is generated depending on the positional relationship between the current flowing through the stator winding and the magnetic flux generated by the permanent magnet of the rotor. Sometimes. When fixed by a brake or the like, the rotor does not move. However, when the rotor is not fixed, there is a possibility that the rotor may rotate due to an electric current that flows to detect an open phase.

  In order to avoid such rotation in phase loss detection, a detection current may be supplied in a direction parallel to the magnetic flux generated by the permanent magnet so that torque is not generated. However, an electric motor drive device that drives a permanent magnet synchronous motor without a sensor that detects a magnetic pole position cannot estimate the position of the magnetic flux by the permanent magnet during a stop in which no voltage is output.

  For example, the estimated position of the magnetic flux by the permanent magnet when the rotor is stopped by the previous drive is stored, and the rotor rotates if a DC current is passed to a position parallel to the stored estimated position of the magnetic flux at the next start-up. do not do. However, this means cannot be adopted when there is a possibility that the rotor is moved during the stop.

  The motor driving device calculates a d-axis voltage command and a q-axis voltage command from the d-axis current command and the q-axis current command, respectively, and performs U-phase, V-phase, Each phase voltage of the W phase is calculated to generate a PWM signal. For this reason, if one phase out of the three phases stops during the previous drive, the current will not flow to the phase when starting from the stop position next time, so only the phase current level is missing. There is a risk of misjudgment that the judgment is being made.

  On the other hand, in an electric motor drive device having a sensor capable of detecting a magnetic pole position, a current phase direction that does not generate torque can be detected in advance before starting. However, as in the case of the sensorless drive described above, if the phase is stopped at a phase where the current of one phase of the three phases becomes 0 during the previous drive, an erroneous determination is made as long as the missing phase determination is made based only on the current level. Fear remains.

JP 2011-51695 A JP 2009-38959 A

  Accordingly, a permanent magnet synchronous motor driving device is provided that can reliably detect a phase loss state without moving the rotor even when the rotor is not fixed by a brake or the like in the configuration of sensorless driving.

  The permanent magnet synchronous motor drive device of the embodiment drives the permanent magnet synchronous motor without including a sensor for detecting the magnetic pole position of the permanent magnet synchronous motor. The permanent magnet synchronous motor drive device includes a voltage source inverter, current detection means, and open phase detection means. The voltage source inverter includes a bridge circuit composed of a pair of an upper arm and a lower arm having switching elements for three phases, and supplies a voltage to the windings of each phase of the permanent magnet synchronous motor. The current detection means detects the phase current of the permanent magnet synchronous motor. The phase loss detection unit includes a voltage supply control unit, a comparison unit, and a phase loss determination unit, and executes a phase loss detection process for the permanent magnet synchronous motor before starting to rotate the permanent magnet synchronous motor.

  The voltage supply control means includes an energization period in which the switching element of one detection phase in the upper arm of the voltage source inverter and the switching element of at least one other phase in the lower arm are turned on, and the switching element that is turned on in this energization period The energization process for supplying alternating current to the detection phase of the permanent magnet synchronous motor in combination with the energization period for turning on the switching element of the arm that forms a pair with the arm having the power is executed for each phase while sequentially changing the detection phase. To do.

  The comparison means obtains a detection current value for phase loss determination according to the magnitude or change of the current flowing in the detection phase based on the current detected by the current detection means in each energization process, and detects the phase failure detection detection current. The value is compared with the reference current value for phase loss determination. The phase loss determination means determines a phase loss when the phase loss detection current value is smaller than the phase loss determination reference current value based on the comparison result.

1 is a configuration diagram of an electric motor drive device according to an embodiment. Diagram showing voltage vector The figure which shows the relationship between a voltage vector and the on-off state of IGBT. (A) is voltage vector V1, (b) is a figure which shows the electric current path when the voltage vector V4 is output. Waveform diagram when the U phase is the detection phase Flow chart of voltage supply control means when the U phase is the detection phase FIG. 6 equivalent diagram when the V phase is the detection phase FIG. 6 equivalent diagram when the W phase is the detection phase Overall flowchart of phase loss detection processing

  An embodiment will be described with reference to the drawings. FIG. 1 shows the configuration of an electric motor drive device that drives a permanent magnet synchronous motor. This electric motor drive device 1 drives the electric motor 2 without so-called sensorless without providing a sensor for detecting the magnetic pole position of the permanent magnet synchronous electric motor 2 (hereinafter referred to as the electric motor 2). In the electric motor 2, three-phase windings 2u, 2v, and 2w are wound around a stator 2s, and a rotor 2r is provided with a permanent magnet.

  The main circuit of the motor drive device 1 includes a converter 5 that rectifies an AC voltage input from the commercial power supply PS and outputs the rectified voltage between the DC power supply lines 3 and 4, a smoothing capacitor 6, a voltage source inverter 7, and current sensors 8 and 9. Etc. The voltage source inverter 7 includes a bridge circuit 12u including a pair of an upper arm 11up having an IGBT 10up and a lower arm 11un having an IGBT 10un, a bridge circuit 12v having a pair of an upper arm 11vp having an IGBT 10vp and a lower arm 11vn having an IGBT 10vn, and an IGBT 10wp. A three-phase bridge comprising a bridge circuit 12w comprising a pair of an upper arm 11wp having an IGBT and a lower arm 11wn having an IGBT 10wn is provided. These IGBTs 10 up to 10 wn (switching elements) are driven by a drive circuit 13.

  The winding terminals of the electric motor 2 as a load are connected to the output terminals of the bridge circuits 12u, 12v, and 12w. Phase loss occurs due to unconnected or incomplete connection between the output terminal and the winding terminal. The current sensors 8 and 9 are current detection means composed of Hall elements and the like. The phase sensors Iu flowing from the output terminal of the bridge circuit 12u to the winding 2u and the phases flowing from the output terminal of the bridge circuit 12w to the winding 2w, respectively. The current Iw is detected.

  The control means 14 is mainly composed of a microcomputer having a CPU, RAM, ROM, EEPROM 15, input / output port, A / D converter 16, timer, PWM signal forming circuit, communication means, and the like. In the ROM, in addition to the hardware inspection program including IGBT 10up to 10wn, the auto tuning program for estimating the motor constant, etc., the rotational drive program for the motor 2 by vector control and V / F constant control, the phase loss is detected. The phase loss detection program is stored. The EEPROM 15 stores the value of time ΔT used in the phase loss detection process described later, in addition to various parameters such as acceleration time, deceleration time, upper limit frequency, lower limit frequency, multistage speed operation frequency, and input / output terminal selection. .

  The control unit 14 functions as a phase loss detection unit. Each block (excluding the EEPROM 15 and the A / D converter 16) described in the control means 14 in FIG. 1 relates to a phase loss detection process executed by the microcomputer CPU according to a phase loss detection program stored in the ROM. Represents a processing function. Processing functions executed in accordance with other processing programs such as a rotation driving program are not shown. In addition, the electric motor driving device 1 includes an operation panel 17 having an operation key, a stop key, an up key, a down key, a mode key, an enter key, and the like, and a display unit 18 having a segment display, an LED, and the like. 19 is provided.

  The A / D converter 16 converts the signal voltage output from the current sensors 8 and 9 into U-phase and W-phase detection currents Iu and Iw, which are digital values. The voltage supply control means 20 causes the alternating current necessary for phase loss detection to flow through the windings 2u, 2v, and 2w of the electric motor 2, so that the voltage output from the voltage source inverter 7 according to the detection phase that is the target of phase loss detection A vector is determined, and an energization period corresponding to the voltage vector is provided. The phase loss detection process is performed for all three phases with the U phase, V phase, and W phase as detection phases in order.

  In order to select and output the voltage vector determined by the voltage supply control means 20, the voltage vector selection means 21 turns on the IGBT corresponding to the voltage vector among the IGBTs 10up to 10wn during each energization period. The driving of the IGBTs 10up to 10wn here, unlike the PWM driving, keeps turning on the IGBTs of the predetermined phases of the upper and lower arms during the energization period having a width of time ΔT.

  Based on the phase currents Iu and Iw detected by the current sensors 8 and 9, the comparison unit 22 obtains a detection current value for phase loss determination corresponding to the magnitude of the current flowing in the detection phase. When the V phase is set as the detection phase, the V phase current Iv is obtained by-(Iu + Iw). Then, the phase loss determination detection current value is compared with a preset phase loss determination reference current value. The phase loss determination means 23 determines a phase loss when the phase loss detection current value is smaller than the phase loss determination reference current value based on the comparison result. If it is determined that the phase is missing, the fact that the phase is missing is displayed on the display unit 18 of the operation panel 19. The detection current setting means 24 obtains the time ΔT of the energization period for outputting the voltage vector and stores it in the EEPROM 15 which is a nonvolatile memory. The voltage supply control means 20 reads the time ΔT from the EEPROM 15 and switches the voltage vector every time the energization period having the time ΔT elapses.

  Next, the operation of the present embodiment will be described in detail with reference to FIGS. The control means 14 executes the phase loss detection process when starting up the electric motor 2 for the first time after turning on the electric power to the electric motor driving device 1 or starting up the electric motor 2. In this case, the hardware inspection program is executed first, and then the phase loss detection program is executed. Thereafter, an auto tuning program is executed to set an initial value, and then a rotation drive program is executed to start and accelerate the electric motor 2. In the phase loss detection process, a voltage is applied from the motor drive device 1 to the motor 2 by a predetermined energization process (energization sequence), and the presence or absence of phase loss between the motor drive device 1 and the motor 2 is observed by observing the flowing current. Determine the phase that is missing. As will be described later, since no torque is generated during the detection period, it is not necessary to fix the rotor 2r with a brake or the like.

  First, voltage vectors used in the phase loss detection process will be described. The voltage type inverter 7 includes a bridge circuit 12x (x is u, v, w) including a pair of an upper arm 11xp having an IGBT 10xp and a lower arm 11xn having an IGBT 10xn. When the IGBT 10xp of the upper arm 11xp is on and 1 when the IGBT 10xn of the lower arm 11xn is on, the voltage vectors V0 to V7 shown in FIG. 2 are expressed by combining them in the order of (U phase V phase W phase). can get.

  In the vector diagram shown in FIG. 2, the directions of V1 (100), V3 (010), and V5 (001) coincide with the directions of the U-phase, V-phase, and W-phase voltages, respectively. The α axis and β axis are two-phase coordinate axes obtained by three-phase to two-phase conversion. FIG. 3 shows the correspondence between the voltage vector and the on / off states of the IGBTs 10up to 10wn. Of these voltage vectors, zero vectors V0 (000) and V7 (111) are not used for the phase loss detection process.

  The voltage supply control means 20 corresponds to the voltage vector in the same direction as the detection phase, and the IGBT 10xp of one detection phase among the upper arms 11up, 11vp, 11wp of the voltage source inverter 7 and the lower arms 11un, 11vn, 11wn. The first energization period for turning on the other two-phase IGBTs 10yn and 10zn is provided. Here, x, y, and z correspond to u, v, and w in no particular order. In addition, the arms 11xn, 11yp, and 11zp that are paired with the arms 11xp, 11yn, and 11zn having the IGBTs 10xp, 10yn, and 10zn that are turned on in the first energization period have a voltage vector opposite to the detection phase. A second energization period for turning on the IGBTs 10xn, 10yp, and 10zp is provided. And a voltage is output according to the energization process (energization sequence) which combined these 1st electricity supply periods and 2nd electricity supply periods.

  Specifically, when the U phase is the detection phase, the detection phase is V1, V4, V4, and V1, and when the V phase is the detection phase, the W phase is the detection phase in the order of V3, V6, V6, and V3. In this case, the voltage vector is switched for each energization period having a time ΔT in the order of V5, V2, V2, and V5. However, when the same voltage vector continues for the time 2ΔT, switching between them is unnecessary. FIGS. 4A and 4B show current paths (thick lines) when voltage vectors V1 (100) and V4 (011) are output, respectively.

  FIG. 5 shows the voltage vector when the U phase is the detection phase, the voltage Vu-vw between the output terminal of the bridge circuit 12u and the output terminals of the bridge circuits 12v and 12w, and the U phase current when there is no open phase. The waveform of Iu is shown. The time ΔT of each energization period is set in advance by the detection current setting means 24 so that the peak value | Iu2 + | or | Iu2- | of the triangular wave current is equal to a predetermined detection current setting value.

  That is, the detection current setting unit 24 switches the voltage vector in the same order as the voltage vector switching by the voltage supply control unit 20 while gradually increasing the voltage vector output time ΔT prior to the phase loss detection process. Repeatedly. Then, the time ΔT when the current peak value | Iu2 + | or | Iu2- | of the detection phase becomes larger than the detection current set value in a state where there is no open phase is stored in the EEPROM 15. The detection current set value may be, for example, about 1/3 to 1/4 of the rated current.

  When there is no phase loss, when the voltage-type inverter 7 outputs a voltage having the voltage vector V1 in the state where the current is set to zero in the phase loss detection process as shown in FIG. 5 (time t1), the U phase The current Iu increases substantially linearly with a slope corresponding to the inductance, and reaches a positive peak value Iu2 + at the time when the voltage vector switches to V4 (time t3). The U-phase current Iu at the central time t2 in this energization period is Iu1 +. When the voltage vector is switched to V4, the U-phase current Iu decreases substantially in a straight line, and becomes zero at the time of transition to the next energization period (time t4).

  Since the voltage vector V4 is the same during the next energization period, the U-phase current Iu continues to decrease substantially linearly, and reaches the negative peak value Iu2- at the time when the voltage vector switches to V1 (time t6). The U-phase current Iu at the central time t5 in this energization period is Iu1-. When the voltage vector is switched to V1, the U-phase current Iu increases in a substantially straight line and becomes zero when the energization process using the U-phase as the detection phase ends (time t7). In this manner, a triangular wave-like alternating current that changes positively and negatively around zero flows in the detection phase and the other two phases.

  Iu2 + and Iu2- are U-phase current values at the time of voltage vector switching, but are easily affected by switching noise at the time of switching. Therefore, the control means 14 inputs the U-phase currents Iu2 + and Iu2- immediately before switching the voltage vector, and sets the detected current value for the phase loss determination. After the time t7, an energization sequence using the V phase as a detection phase and an energization sequence using the W phase as a detection phase are sequentially performed with a standby time necessary for the current to completely settle to zero.

  6, 7, and 8 are flowcharts of the energization sequence (processes A, B, and C) that the voltage supply control unit 20 executes using the U phase, the V phase, and the W phase as detection phases, respectively. In FIG. 6, the timer time t is initialized to 0 (step S1), and the output of the voltage vector V1 and the timer time t are added every control cycle Tc until the timer time t becomes equal to or greater than ΔT (step S2, S3). When the timer time t becomes equal to or greater than ΔT, the U-phase current Iu at that time (actually immediately before ΔT elapses as described above) is input as the detection current value Iu2 + for phase loss determination (step S4).

  Subsequently, the output of the voltage vector V4 and the timer time t are added every control cycle Tc until the timer time t becomes 3ΔT or more (steps S5 and S6). When the timer time t becomes 3ΔT or more, the U-phase current Iu at that time (actually immediately before 3ΔT elapses as described above) is input as the detection current value Iu2- for phase loss determination (step S7). Thereafter, the output of the voltage vector V1 and the addition of the timer time t are executed every control cycle Tc until the timer time t becomes 4ΔT or more (steps S8 and S9). Finally, the timer time t is cleared to 0 and the process ends (step S10). Processing steps S11 to S20 shown in FIG. 7 and processing steps S21 to S30 shown in FIG. 8 are the same as the processing steps S1 to S10 shown in FIG. 6 except for the output voltage vector.

  FIG. 9 is an overall flowchart of the phase loss detection process. The process shown in FIG. 6 is executed with the U phase as the detection phase (step S31), and at least one of the positive current peak value | Iu2 + | and the negative current peak value | Iu2 | It is determined whether or not the phase failure determination reference current value Ith is smaller (step S32). The reference current value Ith for phase loss determination is a value smaller than the rated current of the motor 2, for example, a value of about 10% to 20% of the rated current, or about 1/3 to 1/4 of the detected current set value. Is set to the value of

  If it is determined that the phase is small (YES) in step S32, the U phase is open, so FlagU is set to 1 (step S33). If it is determined that the phase is equal or large (NO), the U phase is open. Since this is not done, FlagU is reset to 0 (step S34). In steps S35 to S38 in which the V phase is the detection phase, FlagV is set or reset by the same processing, and in steps S39 to S42 in which the W phase is the detection phase, FlagW is set or reset by the same processing. After the phase loss detection process is completed, the control unit 14 can recognize the presence or absence of the phase loss and the phase that has lost phase by referring to these FlagU, FlagV, and FlagW.

  In this phase loss detection process, when two or more of the three phases are open, no current flows in any energization sequence. Accordingly, FlagU, FlagV, and FlagW are all 1 and phase loss detection is possible. However, since no current flows at all, it is not possible to specify a phase that is missing. Further, when the V phase where the current sensor is not disposed is lost, no current flows in the U phase and the W phase in the energization sequence using the V phase as the detection phase. Therefore, if the V-phase current Iv is obtained by-(Iu + Iw), the current Iv becomes zero, so that the phase loss can be detected.

  Further, when any of the phases that are not the detection phase is missing, for example, when the U phase is the detection phase and the V phase or the W phase is missing, it is viewed from the voltage type inverter 7. Since the inductance of the electric motor 2 is increased by 4/3, the U-phase current Iu is reduced to about 3/4 as compared with the case where there is no open phase. Since this current value is larger than the reference current value Ith for phase loss determination, it is not determined as phase loss. However, in the energization sequence in which the phase that is out of phase is the detection phase, current does not flow as described above, so that the phase loss can be detected. Therefore, even if the current detection is performed by the current sensors 8 and 9 of only two phases, it is possible to reliably detect the phase loss by executing the energization sequence with all phases in turn as detection phases using this phase loss detection process. Can do.

  In the current waveform shown in FIG. 5, the current change rate during the positive period and the current change rate during the negative period, that is, the current peak value | Iu2 + | during the positive period and the current peak value | Iu2− during the negative period. | Is slightly different. This is because the saturation characteristic of the inductance changes according to the magnetic pole position of the rotor 2r due to the saliency of the electric motor 2. For example, when the direction of the magnetic pole is close to the direction of the U-phase, if the voltage vector V1 is output and a current is passed through the U-phase, the magnetic flux in the U-phase direction increases and the inductance decreases due to saturation. As a result, the current change rate increases and the current peak value | Iu2 + | increases. Conversely, when the voltage vector V4 is output and a current is passed through the U-phase, the magnetic flux in the U-phase direction is reduced, so that saturation is reduced and inductance is increased. As a result, the current change rate decreases and the current peak value | Iu2- | becomes lower.

  In this phase loss detection method, an alternating current flows in the detection phase when there is no phase loss, so that the generated torque takes positive and negative values in the energization sequence per phase. However, if the detected phase is close to the magnetic pole direction due to the change in saturation characteristics described above, there is a possibility that a deviation occurs between the positive generated torque and the negative generated torque due to the difference between the positive and negative current peak values. There is. On the other hand, by executing the energization sequence with all three phases as detection phases in order, the generated torque is sufficiently averaged (cancelled) between the time when the positive torque is generated and the time when the negative torque is generated. Thus, the rotor 2r can be prevented from rotating regardless of the direction of the rotor 2r.

  As described above, in the motor drive device 1 of the present embodiment, each of the three phases is set as the detection phase in turn, and the energization period corresponding to the voltage vector in the opposite phase to the energization period corresponding to the voltage vector in the direction of the detection phase. And a control means 14 for detecting a phase failure. By this energization process, when there is no open phase, alternating currents with substantially equal positive and negative peak values flow through the windings 2u to 2w, so that the positive and negative torques cancel each other and the generated torque becomes effectively zero. In addition, since the energization sequence is performed using all three phases as detection phases, even when there is a phase in which the saturation characteristic changes according to the stop position of the rotor 2r and torque is generated, the generated average torque can be made as close to zero as possible. it can. Thereby, even if the rotor 2r is not fixed by a brake or the like, the phase loss detection process can be executed without the rotor 2r moving.

  When only one phase is missing, the presence / absence of the missing phase and the missing phase can be detected. The same applies to the case where the current sensors 8 and 9 are provided for only two of the three phases. In addition, when two or more phases are simultaneously open, it is not possible to identify the phase that is open, but the presence or absence of the open phase can be detected.

  The detection current setting means 24 sets the width (time ΔT) of the energization period so that the detection current setting value is, for example, about 1/3 to 1/4 of the rated current, and the comparison means 22 sets the detection current setting value. Is used as the reference current value Ith for phase loss determination. As a result, it is possible to accurately determine the phase loss while avoiding the influence of nonlinearity and noise. In addition, since the comparison unit 22 uses the absolute value of the current detected immediately before the voltage vector changes as the detection current value for phase loss determination, the comparison unit 22 is not easily affected by noise generated by switching the voltage vector.

In addition to the embodiment described above, the following configuration may be adopted.
In the phase loss detection process, the comparison means 22 changes between the detected current value that is shorter than the time ΔT from the time when the voltage vector changes, for example, ΔT / 2, and the detected current value immediately before the voltage vector changes. An indefinite value of minutes (difference) may be used as the detection current value for phase loss determination. In FIG. 5, δIu + = | Iu2 + −Iu1 + | or δIu− = | Iu2−−Iu1− | In this case, the condition shown in step S32 shown in FIG. 9 is δIu + <Ith or δIu− <Ith, and the conditions for the V phase and the W phase shown in steps S36 and S40 are the same. The phase failure determination reference current value Ith at this time may be appropriately adjusted according to the current detection interval for obtaining the difference.

Current sensors may be provided for all three phases.
Instead of the current sensors 8 and 9, a phase current may be detected by providing a shunt resistor (current detection means) between the IGBTs 10un, 10vn, 10wn on the lower arm side and the DC power supply line 4. For example, during the period when the first voltage vector V1 of the energization sequence is output with the U phase as the detection phase, current does not flow through the U phase shunt resistor as shown in FIG. A detection current value for phase loss determination of the U phase is generated from the detection current due to the shunt resistance. In the period during which the voltage vector V4 is being output, the detection current value for phase loss determination can be obtained from the U-phase shunt resistance as shown in FIG.

  When the U phase is missing, no current flows through the V and W phases, so Iu = − (Iv + Iw) becomes zero, and the missing phase can be detected. In addition, the U phase is not open, and if any of the V and W phases are open, the current value when the phase is not open is reduced to about 3/4. . Since this current value is larger than the reference current value Ith for phase loss determination, it is not determined as phase loss. However, in the energization sequence in which the phase that is out of phase is the detection phase, current does not flow as described above, so that the phase loss can be detected. Therefore, even when the current is detected by the shunt resistor, the phase loss can be detected correctly.

  As a current detection means that replaces the current sensors 8 and 9, a shunt resistor that detects a direct current input to the voltage source inverter 7 may be provided. This is because the phase current can be detected based on this direct current. This shunt resistor may be provided on the DC power supply line 4 between the capacitor 6 and the voltage source inverter 7, for example. Also in this case, since no current flows in the energization sequence in which the phase that is out of phase is the detection phase, the phase loss can be detected correctly by sequentially setting the three phases as the detection phase.

  In the phase loss detection process, an energization period corresponding to the voltage vector in the direction of the detection phase is combined with an energization period corresponding to the voltage vector in the opposite phase to the detection phase, and an alternating current with an average current of zero is detected in the detection phase. A flowing energization sequence may be employed. Therefore, when the U phase is the detection phase, the voltage vector may be output in the order of V4, V1, V1, V4, or V1, V4, V4, V1, V1, V4, V4, V1,. It may be repeated two or more periods.

  The voltage supply control unit 20 turns on the first detection phase IGBT 10xp of the upper arm 11up, 11vp, 11wp of the voltage source inverter 7 and the other one-phase IGBT 10yn of the lower arm 11un, 11vn, 11wn. An energization process (energization) combining an energization period and a second energization period for turning on the IGBTs 10xn and 10yp of the arms 11xn and 11yp paired with the arms 11xp and 11yn having the IGBTs 10xp and 10yn turned on in the first energization period. A voltage may be output according to a sequence) so that an alternating current flows in the detection phase. Here, x and y correspond to different phases of u, v, and w. Also in this case, the process is executed for all three phases while sequentially changing the detection phase.

  Specifically, with the U phase as the detection phase and the IGBTs 10wp and 10wn turned off, the IGBTs 10up and 10vn are turned on for a time ΔT, the IGBTs 10un and 10vp are turned on for a time 2ΔT, and the IGBTs 10up and 10vn are turned on for a time ΔT. . Subsequently, with the V phase as the detection phase, with the IGBTs 10up and 10un turned off, the IGBTs 10vp and 10wn are turned on for the time ΔT, the IGBTs 10vn and 10wp are turned on for the time 2ΔT, and the IGBTs 10vp and 10wn are turned on for the time ΔT. Subsequently, with the W phase as the detection phase, with the IGBTs 10vp and 10vn turned off, the IGBTs 10wp and 10un are turned on for the time ΔT, the IGBTs 10wn and 10up are turned on for the time 2ΔT, and the IGBTs 10wp and 10un are turned on for the time ΔT. Even if such an energization sequence is used, the phase loss can be detected by the comparison means 22 and the phase loss determination means 23 described above.

The phase loss determination reference current value is not limited to a preset value. For example, you may determine each time according to the electric current value which flows by an electricity supply sequence.
According to the embodiment described above, in a configuration that does not include a sensor that detects the magnetic pole position, even if the rotor is not fixed by a brake or the like, the phase loss detection process is reliably performed without the rotor moving. it can.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  In the drawings, 1 is a motor drive device (permanent magnet synchronous motor drive device), 2 is a permanent magnet synchronous motor, 2u, 2v and 2w are windings, 7 is a voltage source inverter, and 8 and 9 are current sensors (current detection means). 10up to 10wn are IGBTs (switching elements), 11up to 11wp are upper arms, 11un to 11wn are lower arms, 12u, 12v and 12w are bridge circuits, 14 is control means (open phase detection means), and 15 is EEPROM (memory) ), 20 is a voltage supply control means, 22 is a comparison means, and 23 is a phase loss determination means.

Claims (6)

In the permanent magnet synchronous motor drive device for driving the permanent magnet synchronous motor without providing a sensor for detecting the magnetic pole position of the permanent magnet synchronous motor,
A voltage-type inverter that includes a bridge circuit composed of a pair of an upper arm and a lower arm having a switching element for three phases, and supplies a voltage to windings of each phase of the permanent magnet synchronous motor;
Current detecting means for detecting a phase current of the permanent magnet synchronous motor;
A phase loss detection means for performing phase loss detection processing of the permanent magnet synchronous motor before starting rotation driving of the permanent magnet synchronous motor;
The phase loss detection means includes
An energization period for turning on the switching element of one detection phase of the upper arm of the voltage source inverter and the switching element of at least one other phase of the lower arm, and an arm having the switching element turned on in this energization period A voltage supply for executing an energization process for supplying an alternating current to the detection phase of the permanent magnet synchronous motor in combination with an energization period for turning on the switching element of the pair of arms while sequentially changing the detection phase. Control means;
In the energization processing of each detection phase, a detection current value for phase loss determination is obtained according to the magnitude or change amount of the current flowing in the detection phase based on the current detected by the current detection means, and the phase loss determination A comparison means for comparing the detected current value and the reference current value for phase loss determination;
A permanent magnet synchronous motor comprising: a phase loss determining means for determining a phase loss when the detection current value for phase loss determination is smaller than the reference current value for phase loss determination based on the comparison result Drive device. When the switching element of the upper arm of the bridge circuit is on, it is 1 when the switching element of the lower arm is on, and it is expressed by combining them in the order of (U phase V phase W phase), and the voltage source inverter outputs If the possible voltage vectors are defined as V1 (100), V2 (110), V3 (010), V4 (011), V5 (001), V6 (101),
When the U phase is the detection phase, the voltage supply control means is in the order of V1, V4, V4, and V1, and when the V phase is the detection phase, the order is V3, V6, V6, and V3. 2. The permanent magnet synchronization according to claim 1, wherein when the phase is the detection phase, the voltage vector is switched for each energization period having a predetermined time ΔT in the order of V5, V2, V2, and V5. Electric motor drive device.   3. The permanent magnet synchronous motor drive according to claim 2, wherein the comparing means sets the definite value of the current detected by the current detecting means immediately before the voltage vector changes as the detected current value for phase loss determination. apparatus.   The comparison unit includes a current value detected by the current detection unit at a time point shorter than the time ΔT from a time point when the voltage vector changes, and the current detection unit at a time point immediately before the voltage vector changes. 3. The permanent magnet synchronous motor drive device according to claim 2, wherein an indefinite value of a change from the current value detected by the step is used as the detection current value for phase loss determination. While gradually increasing the time ΔT for outputting each voltage vector, the energization process for switching the voltage vector in the same order as the switching of the voltage vector by the voltage supply control means is repeatedly executed, and the current detected by the current detection means A detection current setting means for storing the time ΔT at a time when the peak value becomes larger than a preset detection current setting value;
5. The permanent magnet synchronous motor driving device according to claim 2, wherein the voltage supply control unit switches the voltage vector for each energization period having a time ΔT stored in the memory.   The phase loss determination means determines that the detection phase is a phase loss when the phase loss detection current value is smaller than the phase loss determination reference current value, except when two or more phases are simultaneously phase loss. 6. The permanent magnet synchronous motor drive device according to claim 2, wherein the permanent magnet synchronous motor drive device is determined to be in the state.

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