JP5253264B2 - Motor drive device - Google Patents

Description

  The present invention relates to a motor drive device that controls driving of a switched reluctance motor (hereinafter referred to as an SR motor), and more particularly to reduction of ripple noise (ripple current) associated with excitation switching drive.

  In recent years, SR motors, which are one of motors that do not use magnets, are being used for motors of electric vehicles and the like. The SR motor drive device has independent switching circuits for each phase. When each phase is switched off, the back electromotive force energy of the SR motor coil leaks to the power source side, and a conventional PM motor (Permanent Magnet motor). Ripple noise (ripple current) about twice that of the inverter driving motor drive device is superimposed on a DC power source such as an in-vehicle battery, which adversely affects other devices fed from the power source.

  FIG. 11 shows a schematic configuration of the switch circuit part of the driving device in the case of three-phase excitation driving of the SR motor. The SR motor 1 is formed by arranging a plurality of coils 1u, 1v, 1w of each phase of U, V, W in the stator in order in the circumferential direction and providing a plurality of salient poles on the rotor inside the stator. The coils 1u, 1v, and 1w of the respective phases indicating the series-parallel connected coil groups of the phases are respectively the positive-side switching circuits 2up, 2vp, and 2wp and the negative-side switching circuits 2un, 2vn of the switching circuit unit 2. 2 wn. In the switch circuit unit 2, a DC power source 3 such as an in-vehicle battery is fed between a positive power source terminal 2 p and a negative power source terminal 2 n via a smoothing capacitor 4. Each switching circuit 2up to 2wp on the positive side is formed by connecting two output terminals of a power switching element Qp such as a power IGBT, FET, etc., a cathode and an anode of a reflux diode Dp between power terminals 2p, 2n, Each of the negative side switching circuits 2un to 2wn is formed by connecting two output terminals of a similar switching element Qn, an anode of a reflux diode Dn, and a cathode between power supply terminals 2n and 2p.

  The positive and negative switching elements Qp and Qn of each phase are 120 degrees (one-phase excitation only) or 180 degrees (combination of one-phase excitation and two-phase excitation) each shifted by 120 degrees in electrical angle. It becomes an ON period in order, and it switches by DC control, for example in this ON period, and it interrupts between DC power supply 3 and the coils 1u-1w of each phase. Therefore, for example, the U phase will be described. During the ON period, the current of the DC power source 3 flows through the switching element Qp, the coil 1u, and the switching element Qn to excite the coil 1u. When approaching the magnetic pole of the U phase), the switching elements Qp and Qn are turned off in the non-excitation period (off period), and the ripple current of the counter electromotive force of the coil 1u is changed from the negative side of the coil 1u to the diode Dn and the DC power source. On the 3rd side, it returns to the positive side of the coil 1u via the diode Dp. Note that the reflux also occurs when the PWM control output is turned off (when both the switching elements Qp and Qn are turned off). The same applies to the V phase and the W phase. In this way, the SR motor 1 is driven.

  In order to reduce the ripple noise, a smoothing capacitor 4 is connected in parallel to the DC power supply 3. However, in the case of the motor driving device of the SR motor 1 in which the ripple current increases, the smoothing capacitor 4 has a large capacity and a large cost. Is required.

  Therefore, in this type of motor drive device 1 of the SR motor 1, a switching circuit is provided for each coil of each phase coil group, and for example, each coil of the U phase coil group is energized and excited in a different pattern during the U phase on period. It has been proposed to reduce the ripple noise flowing back to the power supply side (see, for example, Patent Document 1 (abstract, paragraphs [0017]-[0026], FIGS. 4-6, etc.)).

JP 2008-67461 A

  As in the invention described in Patent Document 1, a switching circuit is provided for each coil of each phase coil group, and the ripple noise flowing back to the power source side by energizing and exciting each coil of each phase coil group in a different pattern is provided. If it is reduced, the smoothing capacitor 4 can be reduced in size, but a large number of switching circuits are required, and complicated control for energizing and exciting the coils of the same phase coil group in different patterns is required.

  Therefore, the motor drive device is provided with a ripple reduction control unit, and the coils 1v and 1w of the other phases are connected to the energized phase (U phase) during the U phase excitation period of the SR motor 1 of, for example, an electrical angle of 0 to 180 degrees. Therefore, the smoothing capacitor 4 can be reduced in size by reducing the ripple noise with simple control without providing a switching circuit for each coil of each phase coil group. Can be considered.

  That is, in the one-phase excitation period of the coils 1u to 1w of each phase, for example, the excitation period of only the U phase (the period of 0 to 120 degrees of 120-degree energization (or the period of 60 to 120 degrees of 180-degree energization)). Selects the coil 1v, 1w of the phase with less negative torque generated by energization of the resting V phase and W phase as the phase energized in the opposite phase, and the switching element Qp of the selected phase , Qn are switched so that a current having a magnitude opposite to that of the U-phase switching elements Qp, Qn during energization excitation and a magnitude of, for example, 1/8 to 1/10 of the U-phase current flows. In this way, the negative torque value of the negative phase, which is originally unnecessary in proportion to the square of the current, is suppressed to 1/64 to 1/100 at the maximum, and switching during the excitation period and from the on period to the off period The ripple noise at the time of transition can be reduced by canceling with a reverse phase current based on switching of the switching circuit 2vp, 2vn (or 2wp, 2wn) of the selected pause phase.

  Also, the U-phase and W-phase coils 1u and 1w are excited in a two-phase excitation period of each phase coil 1u to 1w energized by 180 degrees, for example, a U-phase excitation period (a period of 0 to 180 degrees). During the two-phase excitation period (period of electrical angle of 0 to 60 degrees), the W-phase switching elements Qp and Qn are switched and driven in the opposite phase to the energized phase (U-phase) switching elements Qp and Qn. And the V-phase coils 1u and 1v are excited in a two-phase excitation period (a period of 120 to 180 degrees), the V-phase switching elements Qp and Qn are switched to the energized phase (U-phase) switching elements Qp and Qn. Switching drive with reverse phase. In this way, the ripple noise can be canceled and reduced by the two-phase currents that are in opposite phases.

  If the control is performed as described above, the switching elements Qp and Qn of the phase that are in the one-phase excitation period are switched and driven in the opposite phase, and the energization excitation and the subsequent phase are simultaneously performed in the two-phase excitation period. The switching elements Qp and Qn are switched and driven in opposite phases, and the ripple current is canceled and reduced. Therefore, the ripple noise can be reduced by simple control without providing a switching circuit for each coil 1u to 1w of each phase coil group. As a result, the smoothing capacitor 4 can be reduced in size.

  However, in the case of performing reverse-phase switching driving as described above, the torque decreases correspondingly at least in the one-phase excitation period. Further, as the torque generated by the SR motor 1 required by the torque command increases, the ripple noise increases and the temperature of the smoothing capacitor 4 increases. For this reason, if the temperature of the smoothing capacitor 4 rises when a torque command of the maximum torque value is generated due to traveling on an uphill road or sudden acceleration, a large reverse phase according to the current of the energized phase is generated. Since the reverse phase switching drive is controlled so as to generate a current, the maximum torque value required by the torque command cannot be output, and two types of ripple noise reduction and the torque value required by the torque command are generated. There is a problem that the requirements cannot be satisfied at the same time (both).

  An object of the present invention is to satisfy the two requirements at the same time in the motor drive device for driving the SR motor 1, that is, reduction of ripple noise and generation of a torque value required by a torque command.

  In order to achieve the above-described object, the motor driving device of the present invention includes a switching circuit for each phase that forms a separate power feeding path for each phase between the DC power source and the coils for each phase of the SR motor, A motor driving device for driving the SR motor by intermittently connecting between the DC power source and the coil of each phase at the excitation timing of the coil of each phase by each switching circuit, and connected in parallel to the DC power source And a ripple reduction control means for switching the non-excited phase or other switching circuit of the excited phase in the opposite phase to the switching of the excited phase switching circuit to reduce the leakage of the ripple to the power supply side, The reverse-phase switching of the ripple reduction control means is adjusted, and the negative torque value of the SR motor based on the negative-phase switching is the maximum value of the SR motor. It is characterized in that a reverse-phase switching regulation means so as not to exceed the remaining margin value obtained by subtracting the torque command value from the torque value (claim 1).

  In the case of the motor drive device according to the first aspect of the present invention, the ripple reduction control means causes the non-excited phase (resting phase) or before and after the excited phase to be switched with respect to switching of the switching circuit of the excited phase (energized phase). When the switching circuit is switched in reverse phase to reduce ripple leakage to the power supply side, the negative phase switching is adjusted by the negative phase switching adjusting means, and the negative polarity of the SR motor based on the negative phase switching is adjusted. The torque value does not exceed the remaining margin value obtained by subtracting the torque command value from the maximum torque value of the SR motor.

  In this case, the output of the torque value required by the torque command is prioritized to reduce the ripple noise, and the two requirements of reducing the ripple noise and generating the torque value required by the torque command are satisfied simultaneously (both). be able to.

It is a connection diagram of the motor drive device of one embodiment of the present invention. It is a wave form diagram explaining the excitation drive of FIG. It is a wave form diagram explaining reduction of the ripple noise of the two-phase excitation period in FIG. It is explanatory drawing of adjustment of the reverse phase torque of the phase excitation period in FIG. FIG. 2 is a temperature characteristic diagram of the smoothing capacitor of FIG. 1. It is a flowchart for operation | movement description of FIG. 7 is a flowchart for explaining a part of the detailed operation in FIG. 6. 7 is a flowchart for explaining another detailed operation of the other part of FIG. 6. 7 is a flowchart for explaining the detailed operation of still another part of FIG. It is a flowchart for a part of operation | movement description of other embodiment of this invention. It is a connection diagram explaining a prior art example.

  Next, in order to describe the present invention in more detail, embodiments will be described in detail with reference to FIGS.

(One embodiment)
An embodiment will be described with reference to FIGS.

  FIG. 1 is a connection diagram of the present embodiment, and the same reference numerals as those in FIG. 11 denote the same or corresponding components. In order to feedback control the SR motor 1, the momentary torque command Trq based on the detection signal of the voltage V and current I of each phase of the SR motor 1 and the depression amount of the accelerator pedal is formed by a microcomputer or the like. Is input to the drive control unit 51 of the motor control ECU 5 that has been made.

  The drive control unit 51 basically executes the torque value Ti based on the torque command Ti of the torque command and the detection signal of the voltage V and the current I, for example, by a known double feedback control process of the voltage V and the current I. Is output to the drive output unit 52. The three-phase PWM control output is a positive and negative switching circuit 2up, 2un, 2vp for each phase with a pulse width for generating a torque value Ti during the ON period of each phase of 180 degrees shifted by 120 degrees in electrical angle. 2 vn, 2 wp, and 2 Wn switching elements Qp and Qn.

  The drive output unit 52 amplifies the three-phase PWM control output and feeds power to the gates of the switching elements Qp and Qn of each phase, and switches the switching elements Qp and Qn of each phase to switch between the DC power supply 3 and the SR motor 1. The SR motor 1 is driven by intermittently connecting the coils 1u to 1w of each phase.

  FIG. 2 shows changes in the torque output of each phase of the SR motor 1 based on the drive, and the combined torque value of the positive actual torque output becomes a constant torque value. As is apparent from FIG. 2, the U phase of the solid line u is an electrical angle of 0 to 180 degrees in the excitation period (ON period), the V phase of the solid line v is in the excitation period of 120 to 300 degrees, and the W phase of the solid line w. Is an excitation period of 240 to 60 degrees, 0 to 60 degrees is W-phase and U-phase two-phase excitation, 60 to 120 degrees is U-phase one-phase excitation, 120 to 180 degrees is U and V Two-phase excitation of the phase, 180-240 degrees is V-phase one-phase excitation, 240-300 degrees is V-phase, W-phase two-phase excitation, and 300-360 degrees is W-phase one-phase excitation. Conventionally, the switching elements Qp and Qn are kept off during each negative torque output period of FIG. Further, α in FIG. 2 represents an electrical angle at which the two-phase negative torque values are equal.

  Next, the ripple reduction processing unit 53 of the motor control ECU 5 forms the ripple reduction control means and the reverse phase switching adjustment means of the present invention together with the map memory 54.

  For example, if the excitation phase is the U phase, the ripple reduction control means has a one-phase excitation period (a period of 60 degrees to 120 degrees) with respect to switching of the switching elements Qp, Qn in the U-phase switching circuits 2up, 2un. Control target so that non-excited phase (W phase or V phase) switching circuit 2wp, 2wn, 2vp, 2vn switching elements Qp, Qn flow in reverse phase, for example, 1/8 to 1/10 of U phase current. The current value is set, the PWM control output of the corresponding switching drive is formed and output to the drive output unit 52, the leakage of ripple noise to the power supply side is reduced, and the two-phase excitation period (0 ° to 60 °, 120 ° The switching circuit 2wp, 2wn, 2vp of the other excitation phase (W phase (period of 0 degree to 60 degrees) or V phase (period of 120 degrees to 180 degrees)) vn of the switching elements Qp, and controls reversed phase PWM control output Qn reducing leakage of ripple noise on the power supply side. Similarly, when the excitation phase is V phase or W phase, leakage of ripple noise to the power supply side is reduced.

  The non-excitation phase that is driven in the opposite phase during the one-phase excitation period is basically selected so that the negative torque value generated by the opposite phase driving out of the two phases during the pause becomes smaller. Specifically, when the excitation phase is the U phase, as is apparent from FIG. 2, the phase immediately before the W phase is selected as the phase to be driven in the reverse direction between 60 degrees and α degrees, and the α phase is 120 degrees. In the meantime, the next V phase is selected as a phase for reverse phase driving. When the α degree changes depending on the excitation current of the SR motor 1, α for several excitation current values is set in advance in the map memory 54, and α corresponding to the actual excitation current value is interpolated from the set α. Calculate and determine. In this case, α is obtained as α + 120 degrees for the V phase and α + 240 degrees for the W phase, and is set only for the U phase.

  In the reverse-phase drive in the two-phase excitation period, if the U-phase PWM control output is a normal-phase output, the next V-phase PWM control output is reversed, and the next W-phase PWM control output is further output. This can be realized by switching to the negative phase, that is, the positive phase, and switching the PWM control output alternately between the negative phase and the positive phase.

  FIG. 3 shows the SR motor 1 based on the reverse phase PWM control output and the excitation current Ia of the SR motor 1 based on the normal phase PWM control output when the PWM control output is alternately switched between the reverse phase and the normal phase. Excitation current Ib is shown, and the increase (peak) and decrease (valley) of both excitation currents Ia and Ib cancel each other, and leakage of ripple noise to the power supply side is reduced.

  The negative-phase switching adjustment means adjusts the negative-phase switching during the one-phase excitation period of the ripple reduction control means, and the negative torque value of the SR motor 1 changes from the maximum torque value Tmax of the SR motor 1 to the torque value Ti of the torque command. Do not exceed the remaining allowable torque value (margin) minus. That is, when the ripple noise is reduced, the torque value Ti of the torque command continuously becomes the maximum torque value Tmax at the time of starting of the mounted vehicle in which the temperature of the smoothing capacitor 4 becomes high or during high-speed climbing. In such a case, the SR motor 1 cannot generate the torque having the torque value Ti requested by the torque command. For example, when the maximum torque value Tmax that can be generated by the SR motor 1 is 100 Nm, the torque value Ti of the torque command is 90 Nm smaller than that, and the torque value Ti required by the torque command can be generated, 90 Nm = 100 Nm− As is clear from the equation of 10 Nm, a negative torque value of 10 Nm is the margin value of the present invention, and an appropriate negative torque value of this margin value is generated by the switching of the reverse phase, and the temperature of the smoothing capacitor 4 However, when the torque value Ti of the torque command increases to 95 Nm and the negative torque value that can be generated decreases to 5 Nm, as shown by the formula 95 Nm = 100 Nm-5 Nm, If the negative torque value of 10 Nm is continuously generated by the switching, the torque value Ti of 95 Nm required by the torque command cannot be generated. Therefore, in this case, the torque command is given priority, and the negative torque value generated by the reverse-phase switching is suppressed to 5 Nm, which is half the required amount.

  Specifically, a negative torque value that can be generated with respect to the torque value Ti of each torque command of the SR motor 1 is calculated in advance. FIG. 4 shows an example of the graph, where the horizontal axis represents the torque value Ti of the torque command, and the vertical axis represents the negative torque value that can be generated by the reverse-phase switching. Then, map data of the graph of FIG. 4 is stored in the map memory 54. When a torque command is given, a negative torque value (margin value) that can be generated with respect to the torque value Ti is determined from the map data and determined, and the one-phase excitation period is generated so as to generate the determined negative torque value. The PWM control output is adjusted. Note that this adjustment is unnecessary during the two-phase excitation period, and the negative-phase switching adjustment means does not adjust.

  By the way, if the output of the maximum torque value Tmax continues at the time of start or high speed climbing, the temperature of the smoothing capacitor 4 may rise even if the above adjustment is performed, and the smoothing capacitor 4 may be damaged. Therefore, in the present embodiment, as shown in FIG. 1, the temperature of the smoothing capacitor 4 is detected by the temperature sensor 6, and the detected temperature of the temperature sensor 6 is set, for example, for a certain period of time with a torque command of the maximum torque value Tmax. When the temperature rises to the limit temperature θ, the negative phase switching is forcibly stopped by the negative phase switching adjusting means at least for the duration of the torque command. By controlling in this way, the temperature of the smoothing capacitor 4 is surely kept below the limit temperature θ as shown by the solid lines β1 and β2 in FIG. The solid line β1 shows the temperature change when the ripple noise is reduced and reduced by the anti-phase switching during the low load period Tl, and the solid line β2 reduces the ripple noise by the anti-phase switching during the low load period Tl. It shows the temperature change when not. As apparent from these temperature changes, when the ripple noise is reduced by switching in the reverse phase during the low load period Tl, the temperature of the smoothing capacitor 4 is lowered accordingly, so that a high load is applied at the time of start or high speed climbing. Even if it continues somewhat from the period Th, the temperature detected by the temperature sensor 6 does not rise to the set limit temperature θ, and in practice, the ripple noise is constantly reduced by the reverse-phase switching.

  The ripple noise reduction process described above is specifically performed by the software process of the motor control ECU 5 according to the procedure described below.

  FIG. 6 shows the flow of the entire process during running of an electric vehicle equipped with this control apparatus, and the operation setting of the ripple reduction process is performed by A1.

  FIG. 7 shows the processing contents of the operation setting of the ripple reduction processing in step A1, the torque value Ti of the torque command is calculated in step A11, the negative allowable torque value (margin value) is calculated in step A12, and step A13. Thus, it is determined whether or not the reverse-phase switching torque value exceeds the allowable torque value. If the reverse-phase switching torque value does not exceed the allowable torque value, a target current command value for the reverse-phase switching torque value is calculated in step A14. This command value is selected and calculated from the map memory 54 so that the ripple noise reduction effect is maximized and the generated negative torque value is minimized. When the reverse-phase switching torque value exceeds the allowable torque value, the process proceeds from step A13 to step A15, and it is determined whether or not the temperature of the smoothing capacitor 4 has risen to the limit temperature θ. If the temperature does not increase to the limit temperature θ, the process proceeds from step A15 to step A16 to calculate the target current command value for the reverse phase switching of the allowable torque value. The process proceeds to A14, and a target current command value in which ripple noise reduction is prioritized over the torque command is calculated.

  Next, the process proceeds from step A1 to step A2 in FIG. 6 to distinguish and recognize between the one-phase excitation period and the two-phase excitation period. In the one-phase excitation period, the process proceeds to step A3. Move to A4.

  FIG. 8 shows the process of the one-phase excitation period in step A3 in FIG. 6, and detects the electrical angle of the current control of the SR motor 1 from the feedback control state, for example, in step A301, and based on the electrical angle in step A302. Select the excitation phase from U, V, and W. If the excitation phase is the U phase, steps A303 to A306 are used to select the V phase or the W phase as the phase for reverse phase switching based on the detected electrical angle. If the excitation phase is the V phase, in steps A307 to A310, the W phase or the U phase is selected as a phase that performs reverse phase switching based on the detected electrical angle. If the excitation phase is the W phase, in steps A311 to A313, the U phase or the V phase is selected as a phase that performs reverse phase switching based on the detected electrical angle. Further, after selection of a phase to be reversed-phase switched, a target current having a magnitude of a target current command value for reversed-phase switching is set as the selected phase in step A214.

  FIG. 9 shows the process of the two-phase excitation period in step A4 in FIG. 6. In step A41, it is determined whether or not the current excitation phase is positive. If the current excitation phase is positive, step A41 to step A42 are performed. Then, the next excitation phase drive is determined to be the opposite phase, and if the current excitation phase is the opposite phase, the process proceeds from step A41 to step A43, and the next excitation phase drive is determined to be the normal phase.

  Then, the process proceeds from step A3, A4 in FIG. 6 to step A5, the PWM control output of the set (determined) condition is formed, the switching of the reverse phase is executed, the ripple noise reduction process is executed, and the vehicle Step A5 returns from Step A5 to Step A1 through Step A6, and the process is repeated until the driving of (SR motor 1) stops.

  By doing in this way, the non-excitation phase (resting phase) or the other switching circuits 2up to 2wn of the previous and subsequent excitation phases are reversed in phase with respect to the switching of the excitation phase (energization phase) switching circuits 2up to 2wn. When switching to reduce leakage of ripple current to the power supply side, the negative torque value of the SR motor 1 based on the reverse phase switching is obtained by subtracting the torque value Ti of the torque command from the maximum torque value Tmax of the SR motor 1. The remaining margin value can not be exceeded, the output of the torque value Ti of the torque command can be prioritized to reduce the ripple noise, the ripple noise can be reduced, and the maximum torque Tmax required by the torque command can be reduced. The two requirements of generation can be satisfied simultaneously (both). Further, it is possible to ensure that the temperature of the smoothing capacitor 4 does not exceed the limit temperature θ.

(Other embodiments)
Another embodiment will be described with reference to FIGS. 1, 6, and 10.

  In the present embodiment, the temperature sensor 6 in FIG. 1 is omitted. Instead, in step A1 in FIG. 2, the determination in step A15 in FIG. Since the allowable torque value (margin value) continuously becomes a predetermined low torque value (for example, 0) for a predetermined time or longer by step A15 * in FIG. 10 instead of A15, the smoothing capacitor 4 indirectly reaches the limit temperature θ. Judgment that it is rising.

  Therefore, in the case of the present embodiment, the number of parts is further reduced, the cost can be reduced and the size can be further reduced, and the same effect as that of the embodiment can be obtained.

  The present invention is not limited to the above-described embodiments, and various modifications other than those described above can be made without departing from the spirit thereof. The excitation period of each phase of W may be a period of 120 degrees shifted by 120 degrees in electrical angle. In this case, only one phase excitation period occurs. Further, the SR motor 1 may have a configuration of multiphase driving of four phases or more. Further, the SR motor 1 may have any structure.

  Next, it goes without saying that the configuration and processing procedure of the motor control ECU 5 in FIG.

  The present invention can be applied to reduce ripple noise in driving control of the SR motor 1 for various uses.

1 Switched reluctance motor (SR motor)
2 switching circuit section 2up, 2un U phase switching circuit 2vp, 2vn V phase switching circuit 2wp, 2wn W phase switching circuit 3 DC power supply 4 smoothing capacitor 5 motor control ECU
53 Ripple reduction processor

Claims (1)

A switching circuit for each phase that forms an individual power supply path for each phase is provided between the DC power source and the coil for each phase of the switched reluctance motor, and the switching circuit uses the switching timing for exciting the coils for each phase. A motor driving device for driving the switched reluctance motor by intermittently connecting between a DC power source and the coils of each phase;
A smoothing capacitor connected in parallel to the DC power source;
Ripple reduction control means for switching the non-excitation phase or other switching circuit of the excitation phase in reverse phase with respect to the switching of the excitation phase switching circuit to reduce the leakage of the ripple to the power supply side,
Adjusting the reverse phase switching of the ripple reduction control means, the negative torque value of the switched reluctance motor based on the negative phase switching is obtained by subtracting the torque command value from the maximum torque value of the switched reluctance motor. A motor drive device comprising: reverse-phase switching adjustment means for preventing a remaining margin value from being exceeded.

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