JP2019103315A - Driving unit - Google Patents

Abstract

To provide a driving unit capable of reducing a detection error of a phase current of each phase of a motor detected by a current detection part.SOLUTION: Phase currents Iu, Iv and Iw of respective phases of a three-phase AC motor are detected (acquired) at two timings, i.e. a timing after a delay time from a crest of a triangular wave and a timing after the delay time from a trough of the triangular wave. In a two-phase modulation mode in which a switching element of one of three phases of an inverter is stopped from switching and switching elements of the remaining two phases are made to switch, the delay time ΔT is so set that differences between phase currents of the respective phases at the two timings, or a difference between currents of a d axis and a q axis based upon the phase currents of the respective phases at the two timings becomes small.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a drive device, and more particularly to a drive device provided with a three-phase AC motor and an inverter.

  Conventionally, this type of drive device includes a three-phase synchronous motor, a PWM inverter for driving the three-phase synchronous motor, and a current detector for detecting the phase current of each phase of the three-phase synchronous motor. There has been proposed one that controls a PWM inverter by triangular pulse width modulation using a voltage command of each phase of a motor and a triangular wave (carrier wave) (see, for example, Patent Document 1). In this driving device, the phase current of each phase is detected at least once each on the upstream side and the downstream side of the triangular wave. Thereby, an error included in the detected current can be reduced.

JP, 2012-110074, A

  However, in the above-mentioned drive device, there is a possibility that the current detection error can not be sufficiently reduced due to the shift between the current ripple center and the current detection timing due to the influence of switching delay or dead time of the switching element of the PWM inverter. There is.

  The drive device of the present invention has as its main object to further reduce the detection error of the phase current of each phase of the motor detected by the current detection unit.

  The drive device of the present invention adopts the following means in order to achieve the above-mentioned main object.

The driving device of the present invention is
Three-phase AC motor,
An inverter for driving the three-phase AC motor by switching a plurality of switching elements;
A control device that performs switching control of the plurality of switching elements by pulse width modulation control using a voltage command of each phase of the three-phase AC motor and a triangular wave;
A driving device comprising
The control device detects the phase current of each phase of the three-phase AC motor at two timings, a timing after a delay time from the peak of the triangular wave and a timing after the delay time from a valley of the triangular wave;
Furthermore, the control device stops the switching of the switching element of one of the three phases of the inverter, and switches the remaining two phases of the switching element in the two-phase modulation mode. Setting the delay time such that the difference between the phase currents of the respective phases or the currents of the d-axis and the q-axis based on the phase currents of the respective phases at the two timings is reduced.
Make it a gist.

  In the driving device according to the present invention, the phase current of each phase of the three-phase AC motor is detected (acquired) at two timings, that is, the timing after the delay time from the crest of the triangular wave and the timing after the delay time from the trough of the triangular wave. Then, in the two-phase modulation mode in which switching of one of the three phase switching elements of the inverter is stopped and switching of the remaining two phase switching elements is performed, the difference between the phase currents of the two phases at each timing or The delay time is set so that the difference between the d-axis and q-axis currents based on the phase current of each phase of one timing becomes smaller. The inventors found that in the two-phase modulation mode, the frequency of the triangular wave and the frequency of the main component of the current ripple of the phase current of each phase become identical, and the phase current (actual value) at the timing of the peaks and valleys of the triangular wave. Phase current (detection value) is offset to the opposite side, and phase current (detection value) is offset to the opposite side with respect to the phase current (actual value) even at the timing after the delay time from the peaks and valleys of the triangular wave Found out. Therefore, the phase current of each phase of the motor is current rippled by setting the delay time so that the difference between the phase currents of each phase of the two timings or the difference between the currents of the d and q axes of the two timings becomes small. It can be detected near the center of the Thereby, the detection error of the phase current of each phase can be further reduced.

  In the drive device according to the present invention, the control device is configured to calculate the difference between the phase currents of the respective phases of the two timings or the currents of the d axis and q axis of the two timings in the two phase modulation mode. The delay time may be set to minimize the difference. In this way, the phase current of each phase of the motor can be detected near the center of the current ripple.

  In the drive device according to the present invention, the control device is configured to calculate a dq-axis current peak-valley difference based on a difference between the d-axis current at the two timings and a difference between the q-axis currents in the two-phase modulation mode. The processing of storing the combination of the delay time and the dq-axis current peak-to-valley difference is executed while changing the delay time, and among the plurality of combinations of the delay time and the dq-axis current peak-to-valley difference The delay time with the smallest dq-axis current peak-to-valley difference may be set. By so doing, the delay time can be set more appropriately using the dq axis current peak-to-peak difference.

  In the drive device according to the present invention, the control device specifies a stop phase for stopping switching of the switching element in the two-phase modulation mode, and a difference between phase currents of the stop phase of the two timings is a value. The delay time may be set to 0. In this way, it is possible to set the delay time more appropriately by using the phase current of the stop phase.

  In the drive device according to the present invention, the control device switches a stop phase for stopping switching of the switching element by 120 degrees of an electrical angle as the two-phase modulation mode and turns on an upper arm among upper and lower arms of the stop phase. It may be fixed. The control device may also switch the stop phase for stopping the switching of the switching element by 120 degrees of electrical angle in the two-phase modulation mode and fix on the lower arm of the upper and lower arms of the stop phase. Good. Furthermore, the control device switches the stop phase for stopping the switching of the switching element by 60 degrees of electrical angle as the two-phase modulation mode and the upper arm of the upper and lower arms of the stop phase by 60 degrees of electrical angle On-fixing of the lower arm and on-fixing of the lower arm may be performed alternately.

  In the drive device of the present invention, the control device may set the delay time as the two-phase modulation mode when a predetermined learning condition is satisfied. Here, as the "learning condition", a condition in which a predetermined time has elapsed since the learning of the delay time last time, a condition in which the fluctuation amount of torque of the three-phase AC motor and the fluctuation amount of rotational speed are less than each threshold, The condition that the amplitude of the phase voltage command is smaller than the amplitude of the triangular wave is used.

It is a block diagram which shows the outline of a structure of the electric vehicle 20 which mounts the drive device as one Example of this invention. 5 is a flowchart showing an example of a phase current detection routine executed by the electronic control unit 50. 5 is a flowchart showing an example of a phase current detection routine executed by the electronic control unit 50. It is explanatory drawing which shows an example of voltage command Vu *, Vv *, Vw * and a triangular wave in 3 phase modulation mode, and the switching signal of each phase. It is explanatory drawing which shows an example of voltage command Vu * in a 2 phase modulation mode, Vv *, Vw * and a triangular wave, and the switching signal of each phase. Voltage command Vu *, Vv *, Vw * and triangular wave and switching signal of each phase and voltage Vu, Vv, Vw and phase current of U phase (actual value) Iuact and phase current in one cycle of triangular wave in three phase modulation mode (Detected value) FIG. Voltage command Vu *, Vv *, Vw * and triangular wave, switching signal of each phase and voltage Vu, Vv, Vw and phase current of U phase (actual value) Iuact and phase current in one cycle of triangular wave in two-phase modulation mode (Detected value) FIG. It is explanatory drawing which shows an example of voltage command Vu * in the 2 phase modulation mode of a modification, Vv *, Vw *, a triangular wave, and the switching signal of each phase. It is explanatory drawing which shows an example of voltage command Vu * in the 2 phase modulation mode of a modification, Vv *, Vw *, a triangular wave, and the switching signal of each phase. It is a flowchart which shows an example of the phase current detection routine of a modification. Relationship between the current detection delay time ΔT and the phase current (peak) Iua and the phase current (valley) Iub in the two-phase modulation mode of FIG. 5 and when the SW stop phase is U phase and the U phase current Iu is positive. It is explanatory drawing which shows an example. The relationship between the current detection delay time ΔT and the phase current (peak) Iua and the phase current (valley) Iub in the two-phase modulation mode of FIG. 5 and when the SW stop phase is U phase and the U phase current Iu is negative. It is explanatory drawing which shows an example. The relationship between the current detection delay time ΔT and the phase current (peak) Iua and the phase current (valley) Iub in the two-phase modulation mode of FIG. 8 when the SW stop phase is the U phase and the U phase current Iu is positive. It is explanatory drawing which shows an example. The relationship between the current detection delay time ΔT and the phase current (peak) Iua and the phase current (valley) Iub in the two-phase modulation mode of FIG. 8 when the SW stop phase is U phase and the U phase current Iu is negative. It is explanatory drawing which shows an example.

  Next, modes for carrying out the present invention will be described using examples.

  FIG. 1 is a block diagram showing an outline of the configuration of an electric vehicle 20 equipped with a drive device as an embodiment of the present invention. As illustrated, the electric vehicle 20 of the embodiment includes a motor 32, an inverter 34, a battery 36 as a power storage device, and an electronic control unit 50.

  The motor 32 is configured as a synchronous generator motor, and includes a rotor in which permanent magnets are embedded, and a stator in which a three-phase coil is wound. The motor 32 is connected to a drive shaft 26 whose rotor is connected to drive wheels 22 a and 22 b via a differential gear 24.

  The inverter 34 is used to drive the motor 32 and is connected to the battery 36 via the power line 38. The inverter 34 has six transistors T11 to T16 as switching elements, and six diodes D11 to D16 connected in parallel to the six transistors T11 to T16, respectively. The transistors T11 to T16 are arranged in pairs of two so that the source side and the sink side of the positive electrode side line and the negative electrode side line of the power line 38, respectively. Further, a three-phase coil (U-phase, V-phase, W-phase) of the motor 32 is connected to a connection point between the transistors forming the pair of the transistors T11 to T16. Hereinafter, the transistors T11 to T13 are referred to as “upper arm”, and the transistors T14 to T16 are referred to as “lower arm”. Therefore, when the voltage is applied to inverter 34, electronic control unit 50 adjusts the ratio of the on time of paired transistors T11 to T16 to form a rotating magnetic field in the three-phase coil, and thereby the motor 32 is rotationally driven. A smoothing capacitor 39 is attached to the positive electrode line and the negative electrode line of the power line 38.

  The battery 36 is configured as, for example, a lithium ion secondary battery or a nickel hydrogen secondary battery. The battery 36 is connected to the inverter 34 via the power line 38 as described above.

  The electronic control unit 50 is configured as a microprocessor centering on a CPU, and includes, in addition to the CPU, a ROM for storing a processing program, a RAM for temporarily storing data, and an input / output port. Signals from various sensors are input to the electronic control unit 50 through input ports. As a signal input to the electronic control unit 50, for example, the rotational position θm of the rotor of the motor 32 from the rotational position detection sensor (for example, resolver) 32a attached to the rotor of the motor 32, the motor 32 and the inverter 34 And the signals from the current sensors 32u, 32v, 32w attached to the power lines of the respective phases. Further, voltage VH of capacitor 39 (power line 38) from voltage sensor 39a attached between terminals of capacitor 39, voltage Vb of battery 36 from voltage sensor not shown attached between terminals of battery 36, battery The current Ib of the battery 36 from the current detection unit (not shown) attached to the 36 output terminals can also be mentioned. Furthermore, the ignition signal from the ignition switch 60 and the shift position SP from the shift position sensor 62 that detects the operation position of the shift lever 61 can also be mentioned. In addition, the accelerator opening Acc from the accelerator pedal position sensor 64 which detects the depression amount of the accelerator pedal 63, the brake pedal position BP from the brake pedal position sensor 66 which detects the depression amount of the brake pedal 65, and the vehicle speed sensor 68 Vehicle speed V can also be mentioned. The electronic control unit 50 has an AD conversion unit 51 that converts signals (analog values) from the current sensors 32u, 32v, 32w into phase currents Iu, Iv, Iw (digital values) of the respective phases of the motor 32. The electronic control unit 50 outputs a switching control signal to the transistors T11 to T16 of the inverter 34 via an output port. The electronic control unit 50 calculates the electrical angle θe and the rotational speed Nm of the motor 32 based on the rotational position θm of the rotor of the motor 32 from the rotational position detection sensor 32a.

  In the electric vehicle 20 of the embodiment thus configured, the required torque Td * required for the drive shaft 26 is set based on the accelerator opening Acc and the vehicle speed V, and the required torque Td * is set as the torque command Tm * of the motor 32. Set to Then, switching control of the transistors T11 to T16 of the inverter 34 is performed by pulse width modulation control (PWM control) such that the motor 32 is driven by the torque command Tm *.

  Here, control of the inverter 34 will be described. The electronic control unit 50 first converts the U-phase, V-phase and W-phase phase currents Iu, Iv and Iw into d-axis and q-axis currents Id and Iq using the electrical angle θe of the motor 32 (three-phase -2 phase conversion). Subsequently, current commands Id * and Iq * for d axis and q axis are set based on torque command Tm * of motor 32, and current commands Id * and Iq * for d axis and q axis and currents Id and Iq are used. The voltage commands Vd * and Vq * of the d axis and q axis are set. Then, using the electrical angle θe of the motor 32, the voltage commands Vd * and Vq * of the d axis and q axis are coordinate converted (two-phase to three-phase converted) into voltage commands Vu *, Vv *, Vw * of each phase. The PWM signals of the transistors T11 to T16 are generated by comparing the voltage commands Vu *, Vv *, Vw * of each phase with the triangular wave (carrier wave). Thus, when the PWM signals of the transistors T11 to T16 are generated, the transistors T11 to T16 are switched using the PWM signals.

  Next, the operation of the drive device mounted on the electric vehicle 20 of the embodiment configured in this way, in particular, detects the phase current Iu, Iv, Iw of each phase of the motor 32, specifically, the current sensor 32u, The operation at the time of converting signals (analog values) from 32v and 32w into phase currents Iu, Iv and Iw (digital values) of respective phases will be described. 2 and 3 are flowcharts showing an example of a phase current detection routine executed by the electronic control unit 50. This routine is executed as interrupt processing at each timing of the crest and trough of the triangular wave. In addition, 4 kHz, 5 kHz, 6 kHz etc. are used as frequency (carrier frequency) fc of a triangular wave, for example.

  When the phase current detection routine of FIGS. 2 and 3 is executed, the electronic control unit 50 waits for the current detection delay time ΔT to elapse, ie, after the current detection delay time ΔT of the crests and valleys of the triangular wave ( Step S100) detects the phase currents Iu, Iv, Iw of each phase of the motor 32. Specifically, signals (analog values) from the current sensors 32u, 32v, 32w are phase currents Iu, Iv, It is converted into Iw (digital value) (step S110). Then, using the electrical angle θe of the motor 32, the phase currents Iu, Iv, Iw of each phase are coordinate-converted (three-phase / two-phase conversion) to currents Id, Iq of the d axis and q axis (step S120). Here, as the current detection delay time ΔT, a time set by a process described later is used. When the currents Id and Iq for the d and q axes are set, the transistor of the inverter 34 is controlled by PWM control based on the currents Id and Iq for the d and q axes as described above according to a routine different from this routine. The switching control of T11 to T16 is performed.

  Subsequently, it is determined whether a learning condition of the current detection delay time ΔT is satisfied (step S130). Here, as a learning condition, for example, a predetermined time (for example, about several minutes to several tens of minutes) has elapsed since the learning of the current detection delay time ΔT was performed last time, and the torque Tm of the motor 32 is The fluctuation amount of the rotational speed Nm and the fluctuation amount of the rotational speed Nm are equal to or less than the respective threshold values, and the condition is used in which the amplitude of the voltage command Vu *, Vv *, Vw * of each phase is smaller than that of the triangular wave. The learning condition is not limited to this, and can be set as appropriate.

  If it is determined in step S130 that the learning condition is not satisfied, the three-phase modulation mode is set (step S135), and this routine is ended. Here, the three-phase modulation mode is a mode in which three-phase transistors (all of the transistors T11 to T16) of the inverter 34 are switched. FIG. 4 is an explanatory view showing an example of the voltage commands Vu *, Vv *, Vw * and the triangular wave and the switching signal of each phase in the three-phase modulation mode. The switching signal of each phase corresponds to the PWM signal of the upper arm of each phase (the on / off inverted signal is the PWM signal of the lower arm). Actual switching of the transistors T11 to T16 is performed in consideration of the switching delay and dead time of the transistors T11 to T16 based on the PWM signal (switching signal) of the transistors T11 to T16.

  If it is determined in step S130 that the learning condition is satisfied, the two-phase modulation mode is set (step S140). Here, in the two-phase modulation mode, switching of one of the three phases (for example, U-phase transistors T11 and T14) of the three phases of the inverter 34 is stopped and the remaining two-phase transistors (for example, V-phase, W In this mode, switching of the phase transistors T12, T13, T15 and T16) is performed. One phase (hereinafter referred to as “SW stop phase”) for stopping the switching of the transistor is determined based on the electrical angle θe of the motor 32. FIG. 5 is an explanatory view showing an example of the voltage commands Vu *, Vv *, Vw * and the triangular wave and the switching signal of each phase in the two-phase modulation mode. In the embodiment, as the two-phase modulation mode, as shown in FIG. 5, the SW stop phase is switched by 120 degrees of the electrical angle θe and the upper arm of the SW stop phase is fixed on (the lower arm is fixed off). did. The reason for setting the two-phase modulation mode will be described later.

  Subsequently, it is determined whether all the examinations of the candidates for the current detection delay time ΔT have been completed (steps S150 and S152). Here, as candidates for the current detection delay time ΔT, for example, 1 μsec, 2 μsec, etc. can be mentioned when the period of the triangular wave is about 200 msec (the carrier frequency is about 5 kHz).

  When it is determined in steps S150 and S152 that all the examinations of the current detection delay time ΔT candidate have not been completed, the interrupt processing (execution of this routine) at this time has the triangular wave timing and the valley timing. It is determined at which timing of the interrupt process the interrupt process (step S160). Then, when it is determined that the interrupt processing of this time is the interrupt processing of the peak timing of the triangular wave, the currents Id and Iq of the d axis and q axis calculated in step S120 are the currents of the d axis and q axis (peak) When Ida and Iqa are set (step S170) and it is determined that the current interrupt processing is interrupt processing at the timing of the valley of the triangular wave, currents Id and Iq of the d and q axes are d and q axes, respectively. The current (valley) Idb, Iqb is set (step S180).

  Subsequently, it is judged whether or not the data of the current (peak) Ida, Iqa of the d-axis and q-axis and the current (valley) Idb, Iqb are aligned (step S190). End the routine

  If it is determined in step S190 that the data of the d-axis and q-axis current (peak) Ida and Iqa and the current (valley) Idb and Idq are aligned, the current from d-axis and q-axis (peak) Ida and Iqa (Valley) Idb and Idq are reduced to calculate the current valley difference ΔId and ΔIq of the d axis and q axis (step S200), and the square of the calculated current valley difference ΔId of the d axis and the current valley difference ΔIq of the q axis The dq axis current peak / valley difference ΔIdq is calculated as the square root of the sum of the squares and the square (step S210).

  Then, it is determined whether or not it is possible to apply a filtering process (a smoothing process) to the dq axis current peak-to-peak difference ΔIdq (step S220). This determination is performed, for example, by determining whether or not a predetermined time Δtf (for example, 90 msec, 100 msec, 110 msec, etc.) has elapsed after the current detection delay time ΔT is made the current value. If it is determined that filtering can not be performed on the dq axis current peak / valley difference ΔIdq, the present routine ends.

  If it is determined in step S220 that the dq axis current peak-to-valley difference ΔIdq can be subjected to the filter processing (dampening processing), the dq axis current peak-to-valley difference ΔIdq is subjected to the filtering processing (damping processing) The dq axis current peak / valley difference (filter value) ΔIdq is calculated (step S230). This process is performed, for example, by performing an averaging process on the dq-axis current peak-to-valley difference ΔIdq using the predetermined time Δtf as a time constant.

  Next, a timer value Tti as an elapsed time after selecting a candidate for the current detection delay time ΔT is compared with a predetermined time Ttiref (step S240). Here, the predetermined time Ttiref is a time required to determine whether the dq axis current peak / valley difference (filter value) ΔIdqf is stable, and is determined as a time sufficiently longer than the predetermined time Δtf, for example, A time such as 5 times, 7 times, 10 times or the like of the predetermined time Δtf is used. When the timer value Tti is less than the predetermined time Ttiref, the present routine ends.

  If it is determined in step S240 that the timer value Tti is equal to or greater than the predetermined time Ttiref, a combination of the current detection delay time ΔT and the dq axis current peak-to-peak difference (filter value) ΔIdqf is stored (step S250). Here, the combination of the current detection delay time ΔT and the dq axis current peak / valley difference (filter value) ΔIdqf is, for example, the current qq current peak / valley difference (filter value) ΔIdqf of 20 A when the current detection delay time ΔT is 1 μsec. When the detection delay time ΔT is 2 μsec, the dq axis current peak / valley difference (filter value) ΔIdqf is stored as 10 A,.

  Subsequently, the next value is selected from untested candidates among the candidates for the current detection delay time ΔT (step S260), and the timer value Tti is reset to the value 0 and then the clocking is started (step S270). End this routine. When there are no untested candidates among the candidates for the current detection delay time ΔT, the current current detection delay time ΔT is reselected.

  When there is no untested candidate among the candidates for the current detection delay time ΔT in step S260, all the tests for the current detection delay time ΔT candidate are completed in steps S150 and S152 when the present routine is executed next time. (There is no untested candidate.) Current detection delay time ΔT and dq-axis current peak-to-valley difference (filter value) ΔIdqf Among multiple combinations of dq-axis current peak-to-valley difference (filter value) ΔIdqf Current detection The delay time ΔT is selected and set (step S280), and this routine is ended. Thus, when the current detection delay time ΔT is set, when the present routine is executed next time or later, the current detection delay time ΔT is used (held) until the learning condition is satisfied next time.

  Next, the reason for setting the two-phase modulation mode when the learning condition is satisfied in step S130 of the phase current detection routine of FIGS. 2 and 3 (when learning the current detection delay time ΔT) will be described. FIG. 6 shows the voltage commands Vu *, Vv *, Vw * and the triangular wave, the switching signal of each phase, and the voltages Vu, Vv, Vw and the U-phase phase current (actual value) in one cycle of the triangular wave in the three-phase modulation mode. It is an explanatory view showing Iuact and phase current (detection value) Iu. FIG. 7 shows the voltage commands Vu *, Vv *, Vw * and the triangular wave, the switching signal of each phase, and the voltages Vu, Vv, Vw and the U-phase phase current (actual value) in one cycle of the triangular wave in the two-phase modulation mode. It is an explanatory view showing Iuact and phase current (detection value) Iu. In FIG. 6 and FIG. 7, the hatched portions are the delay of the phase voltage with respect to the switching signal of each phase due to the switching delay and dead time of the transistor of each phase. 6 and 7 show the case where the phase current (actual value) Iuact of the U phase is positive. The round marks of the U phase current (detected value) Iu in FIGS. 6 and 7 represent the phase current (detected value) Iu at the timing of the peaks and valleys of the triangular wave, and the triangular marks represent the peaks and valleys of the triangular wave. To the phase current (detected value) Iu at a timing after the delay time ΔTa.

  In the three-phase modulation mode, as can be seen from FIG. 6, the main component of the current ripple of the phase current (actual value) Iuact and the phase current (detected value) Iu becomes twice the frequency of the triangular wave, and the peaks and valleys of the triangular wave At the timing, the phase current (detected value) Iu is offset to the same side (larger side) with respect to the phase current (actual value) Iuact, and the phase current (actual value) also at the timing after delay time ΔTa from the crest and valley of the triangular wave. The phase current (detected value) Iu is offset to the same side (large side) with respect to Iuact). Therefore, it is difficult to set the current detection delay time ΔT properly.

  On the other hand, in the two-phase modulation mode, as shown in FIG. 7, the main components of the current ripple of the phase current (actual value) Iuact and the phase current (detection value) Iu have the same frequency as the triangular wave, The phase current (detected value) Iu is offset to the opposite side with respect to the phase current (actual value) Iuact at the timing of peaks and valleys, and also at the timing after delay time ΔTa from the peaks and valleys of the triangular wave Value) The phase currents (detected values) Iu are offset to the opposite sides with respect to Iuact. Therefore, the delay time at which the difference between the phase current (detected value) Iu at the timing after the delay time ΔTa from the peak of the triangular wave and the phase current (detected value) Iu at the timing after the delay time ΔTa from the valley of the triangular wave becomes minimum. By setting ΔTa to the current detection delay time ΔT in the process of step S280, it is possible to detect the phase current Iu of the U phase near the center of the current ripple. In the embodiment, on the basis of this, the dq-axis current peak-to-valley difference (filter value) ΔIdqf is calculated using the currents Id and Iq of the d-axis and q-axis based on the phase currents Iu, Iv and Iw of each phase, and current detection The relationship between the delay time ΔT and the dq axis current peak-to-peak difference (filter value) ΔIdqf is determined, and the current detection delay time ΔT that minimizes the dq-axis current peak to valley difference (filter value) ΔIdqf is selected. Thus, the phase currents Iu, Iv, Iw of the respective phases of the motor 32 can be detected near the center of the current ripple. As a result, the detection error of the phase currents Iu, Iv, Iw of each phase can be further reduced.

  In the drive unit mounted on the electric vehicle 20 according to the embodiment described above, the currents Id and Iq of the d axis and the q axis based on the phase currents Iu, Iv and Iw of each phase of the motor 32 in the two phase modulation mode. The dq-axis current peak-to-valley difference (filter value) ΔIdqf is calculated using the above to find the relationship between the current detection delay time ΔT and the dq-axis current peak-to-peak difference (filter value) ΔIdqf. Then, the current detection delay time ΔT at which the dq-axis current peak-to-valley difference (filter value) ΔIdqf is minimized is selected. Thus, the phase currents Iu, Iv, Iw of the respective phases of the motor 32 can be detected near the center of the current ripple. As a result, the detection error of the phase currents Iu, Iv, Iw of each phase can be further reduced.

  In the drive device mounted on the electric vehicle 20 of the embodiment, in the two-phase modulation mode, the dq-axis current valley difference among a plurality of combinations of the current detection delay time ΔT and the dq-axis current peak-valley difference (filter value) ΔIdqf (Filter Value) The current detection delay time ΔT with the minimum ΔIdqf is selected. However, the current detection delay time ΔT may be selected from among a plurality of combinations of the current detection delay time ΔT and the d-axis current peak-to-valley difference ΔIdq. That is, a combination of the current detection delay time ΔT and the d-axis current peak-to-peak difference ΔIdq may be stored without filtering the dq-axis current peak-to-peak difference ΔIdq.

  In the driving device mounted on the electric vehicle 20 of the embodiment, as shown in FIG. 5 as the two-phase modulation mode, the SW stop phase is switched by 120 degrees of the electric angle θe and the upper arm of the SW stop phase is fixed on. (The lower arm is fixed off). However, as shown in FIG. 8, the SW stop phase may be switched by 120 degrees of the electrical angle θe and the lower arm of the SW stop phase may be on fixed (the upper arm may be off fixed). Further, as shown in FIG. 9, the SW stop phase is switched by 60 degrees of the electrical angle θe while the upper arm of the SW stop phase is fixed by 60 degrees of the electrical angle θe (lower arm is fixed) and the lower arm is turned on. Fixing (off fixing of the upper arm) may be performed alternately. In the case of FIG. 9, there is an advantage that heat generation due to switching of the transistors T11 to T16 can be equalized by the upper and lower arms.

  In the drive device mounted on the electric vehicle 20 according to the embodiment, the electronic control unit 50 executes the phase current detection routine of FIGS. 2 and 3, but instead, the phase current detection routine of FIG. May be performed.

  When the phase current detection routine of FIG. 10 is executed, the electronic control unit 50 waits for the current detection delay times ΔTu, ΔTv, ΔTw to elapse, that is, the current detection delay times ΔTu of peaks and valleys of the triangular wave. After ΔTv, ΔTw (step S300), the phase currents Iu, Iv, Iw of each phase of the motor 32 are detected. Specifically, signals (analog values) from the current sensors 32u, 32v, 32w are The current Iu, Iv, Iw (digital value) are converted (step S310). Here, for the current detection delay times ΔTu, ΔTv and ΔTw, the time set by the processing described later is used. That is, the current detection delay times ΔTu, ΔTv, ΔTw are not necessarily the same time. Therefore, the timings of detecting the phase currents Iu, Iv, Iw of the respective phases of the motor 32 are not necessarily simultaneous.

  Subsequently, it is determined whether the learning conditions of the current detection delay times ΔTu, ΔTv, ΔTw are satisfied (step S320). Here, as the learning condition, for example, a predetermined time (for example, several minutes to several tens of minutes) has elapsed since the learning of the current detection delay times ΔTu, ΔTv, ΔTw was performed last time, and the motor The condition that the number of revolutions Nm of 32 is approximately 0 (the absolute value of the number of revolutions Nm is less than or equal to the threshold) and the amplitude of the voltage command Vu *, Vv *, Vw * of each phase is smaller than the amplitude of the triangular wave Etc. are used. The learning condition is not limited to this, and can be set as appropriate. When it is determined in step S320 that the learning condition is not satisfied, the three-phase modulation mode is set (step S330), and the present routine is ended.

  When it is determined in step S320 that the learning condition is satisfied, the two-phase modulation mode is set (step S340), and the SW stop phase (one phase for stopping switching of the transistor) is U phase, V phase, W phase It is determined which phase it is (step S350). In this modification, as the two-phase modulation mode, as in the embodiment, the SW stop phase is switched by 120 degrees of the electrical angle θe and the upper arm of the SW stop phase is fixed on (the lower arm is fixed off). (See FIG. 5).

  When it is determined in step S350 that the SW stop phase is the U phase, it is determined which of the timing of the peak of the triangular wave and the timing of the valley the interrupt processing of this time (execution of this routine) is. It determines (step S360). Then, when it is determined that the current interrupt processing is interrupt processing of the triangular wave timing, the U-phase phase current Iu is set to the phase current (peak) Iua (step S370), and the current interrupt processing is performed. If it is determined that the interrupt processing of the timing of the valley of the triangular wave is performed, the U-phase phase current Iu is set to the phase current (valley) Iub (step S380).

  Subsequently, it is determined whether or not the data of the phase current (mountain) Iua and the phase current (valley) Iub are aligned (step S390). If it is determined that the data is not aligned, the present routine is ended.

  If it is determined in step S390 that the data of the phase current (peak) Iua and the phase current (valley) Iub are all aligned, it is determined whether the phase current Iu of the U phase is positive (step S400). When it is determined that the U-phase phase current Iu is positive, the U-phase current deviation ΔIu is calculated by subtracting the phase current (valley) Iub from the phase current (peak) Iua (step S410). When it is determined that the current Iu is not positive, the phase current (peak) Iua is subtracted from the phase current (valley) Iub to calculate a U-phase current deviation ΔIu (step S420).

  When the U-phase current deviation ΔIu is calculated in this way, the current detection delay time ΔTu is set (corrected) by feedback control so that the U-phase current deviation ΔIu becomes a value 0 (step S430), and this routine is ended.

  FIG. 11 shows the current detection delay time ΔTu and the phase current (peak) Iua and the phase current (valley) when the SW stop phase is the U phase and the U phase current Iu is positive in the two-phase modulation mode of FIG. It is an explanatory view showing an example of a relation with Iub. 12 shows the current detection delay time ΔTu, the phase current (peak) Iua, and the phase current in the two-phase modulation mode of FIG. 5 when the SW stop phase is the U phase and the U phase current Iu is negative. Valley) It is explanatory drawing which shows an example of a relationship with Iub. The relationship of FIG. 11 is obtained from the relationship between the phase current (actual value) Iuact of the U phase and the phase current (detected value) Iu of FIG. FIG. 12 can be considered the same as FIG. In the case of FIG. 11, the phase current (valley) Iub is subtracted from the current (peak) Iua to calculate the U-phase current deviation ΔIu. In the case of FIG. 12, the phase current (mountain) Iua is subtracted from the phase current (valley) Iub U phase current deviation ΔIu will be calculated. Then, by setting the current detection delay time ΔTu by feedback control so that the U-phase current deviation ΔIu becomes a value 0, it is possible to detect the phase current Iu of the U-phase near the center of the current ripple. Thereby, the detection error of the phase current of each phase can be further reduced.

  If it is determined in step S350 that the SW stop phase is the V phase or the W phase, the current detection delay time ΔTv or the current detection delay time ΔTw is set (corrected) as in the case where the SW stop phase is the U phase. Then (steps S440 to S510 or steps S520 to S590), this routine ends. A brief description will be given below.

  When the SW stop phase is the V phase, the phase current Iv of the V phase is set to the phase current (peak) Iva when the current interrupt processing (execution of this routine) is interrupt processing of the peak of the triangular wave. When the current interrupt processing is interrupt processing at the timing of the valley of the triangular wave, the phase current Iv of the V phase is set to the phase current (valley) Ivb (steps S440 to S460). Subsequently, when the data of the phase current (peak) Iva and the phase current (valley) Ivb are aligned (step S 470), when the phase current Iv of the V phase is positive, the phase current (peak) Iva to the phase current (Valve) Ivb is reduced to calculate V-phase current deviation ΔIv. When V-phase current Iv is not positive, phase current (valley) Ivb is subtracted from phase current (valley) Ivb to calculate V-phase current deviation ΔIv. (Steps S480 to S500). When the V-phase current deviation ΔIv is calculated in this manner, the current detection delay time ΔTv is set (corrected) by feedback control so that the V-phase current deviation ΔIv becomes 0 (step S510), and the present routine is ended.

  When the SW stop phase is the W phase, the phase current Iw of the W phase is set to the phase current (peak) Iwa when the current interrupt processing (execution of this routine) is interrupt processing of the peak of the triangular wave. When the current interrupt process is an interrupt process at the timing of the valley of the triangular wave, the phase current Iw of the W phase is set to the phase current (valley) Iwb (steps S520 to S540). Subsequently, when the data of the phase current (peak) Iwa and the phase current (valley) Iwb are aligned (step S 550), when the phase current Iw of the W phase is positive, the phase current (peak) Iwa to the phase current Calculate the W-phase current deviation ΔIw by subtracting the phase current (peak) Iwa from the phase current (valley) Iwb when the W-phase current deviation ΔIw is calculated by subtracting the (valley) Iwb. (Steps S560 to S580). When the W-phase current deviation ΔIw is calculated in this way, the current detection delay time ΔTw is set (corrected) by feedback control so that the W-phase current deviation ΔIw becomes a value 0 (step S590), and this routine is ended.

  As described above, in the two-phase modulation mode, the SW stop phase is switched by 120 degrees of the electrical angle θe, and the upper arm of the SW stop phase is fixed on (the lower arm is fixed off). Based on this, after learning of the current detection delay times ΔTu, ΔTv, ΔTw is started (after the two-phase fixed mode is started), the motor 32 rotates by a predetermined cycle (for example, about several cycles) at the electrical angle θe. Or when any of the current detection delay times ΔTu, ΔTv, ΔTw set in steps S430, S510, S590 is stable (when the amount of fluctuation is less than a predetermined amount over a predetermined time), etc. It is conceivable to end learning of the delay times ΔTu, ΔTv, ΔTw. When learning of the current detection delay times ΔTu, ΔTv, ΔTw is finished in this way, when the present routine is executed next time or later, the current detection delay times ΔTu, ΔTv, ΔTw are until the learning condition is satisfied next time. Used (held).

  In this modification, as shown in FIG. 5, as the two-phase modulation mode, the SW stop phase is switched by 120 degrees of the electrical angle θe and the upper arm of the SW stop phase is fixed on (the lower arm is fixed off). It was a thing. In this case, the relationship between the current detection delay time ΔTu and the phase current (peak) Iua and the phase current (valley) Iub when the SW stop phase is the U phase and the U phase current Iu is positive is as shown in FIG. The relationship between the current detection delay time ΔTu and the phase current (peak) Iua and the phase current (valley) Iub when the SW stop phase is U phase and the U phase current Iu is negative is as shown in FIG. become.

  However, as shown in FIG. 8 as the two-phase modulation mode, the SW stop phase is switched by 120 degrees of the electrical angle θe and the lower arm of the SW stop phase is fixed on (the upper arm is fixed off). Good. In this case, the relationship between the current detection delay time ΔTu and the phase current (peak) Iua and the phase current (valley) Iub when the SW stop phase is the U phase and the U phase current Iu is positive is as shown in FIG. The relationship between the current detection delay time ΔTu and the phase current (peak) Iua and the phase current (valley) Iub when the SW stop phase is U phase and the U phase current Iu is negative is as shown in FIG. become. Therefore, in the case of FIG. 13, the U-phase current deviation ΔIu is calculated by subtracting the current (peak) Iua from the phase current (valley) Iub, and in the case of FIG. 14 the phase current (valley) Iub from the phase current (peak) Iua. It is sufficient to calculate the U-phase current deviation ΔIu by subtraction, and set the current detection delay time ΔTu by feedback control so that the U-phase current deviation ΔIu becomes a value 0. In this way, the U-phase phase current Iu can be detected near the center of the current ripple, and detection errors of the phase current of each phase can be further reduced. The setting of the current detection delay time ΔTv and the current detection delay time ΔTw when the SW stop phase is the V phase or the W phase can be considered in the same manner.

  In the two-phase modulation mode, as shown in FIG. 9, the SW stop phase is switched by 60 degrees of the electrical angle θe and the upper arm of the SW stop phase is fixed at 60 degrees of the electrical angle θe And the lower fixation of the lower arm (the upper fixation of the upper arm) may be performed alternately. In this case, when the SW stop phase is the U phase and the upper arm is fixed on, the relationship between the current detection delay time ΔTu and the phase current (peak) Iua and the phase current (valley) Iub is shown in FIG. The relationship between the current detection delay time ΔTu and the phase current (peak) Iua and the phase current (valley) Iub is as shown in FIG. It becomes like FIG. Therefore, U-phase current deviation ΔIu may be calculated according to which of FIGS. 11 to 14 corresponds, and current detection delay time ΔTu may be set by feedback control such that U-phase current deviation ΔIu has a value of 0. . In this way, the U-phase phase current Iu can be detected near the center of the current ripple, and detection errors of the phase current of each phase can be further reduced. The setting of the current detection delay time ΔTv and the current detection delay time ΔTw when the SW stop phase is the V phase or the W phase can be considered in the same manner.

  Although not particularly described in the embodiment or this modification, the electronic control unit 50 executes the phase current detection routine shown in FIGS. 2 and 3 in a region where the absolute value of the rotational speed Nm of the motor 32 is equal to or greater than the threshold Nmref. The phase current detection routine of FIG. 10 may be executed in a region where the absolute value of the rotation speed Nm of the motor 32 is less than the threshold Nmref (near the value 0).

  In the electric vehicle 20 of the embodiment, the battery 36 is used as the power storage device, but instead of the battery 36, a capacitor may be used.

  In the embodiment, the drive unit mounted on the electric vehicle 20 including the motor 32 is used. However, the drive unit may be mounted on a hybrid vehicle equipped with an engine in addition to the motor 32, or may be mounted on a moving object such as a vehicle other than a car, a ship, or an aircraft. It may be in the form of a drive device mounted on non-moving equipment such as construction equipment.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the section of "Means for Solving the Problems" will be described. In the embodiment, the motor 32 corresponds to the “three-phase alternating current motor”, the inverter 34 corresponds to the “inverter”, and the electronic control unit 50 corresponds to the “control device”.

  In addition, the correspondence of the main elements of the embodiment and the main elements of the invention described in the section of the means for solving the problem implements the invention described in the column of the means for solving the problem in the example. The present invention is not limited to the elements of the invention described in the section of “Means for Solving the Problems”, as it is an example for specifically explaining the mode for carrying out the invention. That is, the interpretation of the invention described in the section of the means for solving the problem should be made based on the description of the section, and the embodiment is an embodiment of the invention described in the section of the means for solving the problem. It is only a specific example.

  As mentioned above, although the form for implementing this invention was demonstrated using the Example, this invention is not limited at all by these Examples, In the range which does not deviate from the summary of this invention, it becomes various forms Of course it can be implemented.

  The present invention is applicable to the drive industry and the like.

  DESCRIPTION OF SYMBOLS 20 electric vehicle, 22a, 22b drive wheel, 24 differential gear, 26 drive shaft, 32 motor, 32a rotational position detection sensor, 32u, 32v, 32w current detection unit, 34 inverter, 36 battery, 38 power line, 39 capacitor, 39a Voltage sensor, 50 electronic control units, 60 ignition switches, 61 shift levers, 62 shift position sensors, 63 accelerator pedals, 64 accelerator pedal position sensors, 65 brake pedals, 66 brake pedal position sensors, 68 vehicle speed sensors, D11 to D16 diodes, T11 to T16 transistors.

Claims (1)

Three-phase AC motor,
An inverter for driving the three-phase AC motor by switching a plurality of switching elements;
A control device that performs switching control of the plurality of switching elements by pulse width modulation control using a voltage command of each phase of the three-phase AC motor and a triangular wave;
A driving device comprising
The control device detects the phase current of each phase of the three-phase AC motor at two timings, a timing after a delay time from the peak of the triangular wave and a timing after the delay time from a valley of the triangular wave;
Furthermore, the control device stops the switching of the switching element of one of the three phases of the inverter, and switches the remaining two phases of the switching element in the two-phase modulation mode. Setting the delay time such that the difference between the phase currents of the respective phases or the currents of the d-axis and the q-axis based on the phase currents of the respective phases at the two timings is reduced.
Drive device.

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