JP6946988B2 - Drive device - Google Patents

Description

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

Conventionally, this type of drive device includes a 3-phase synchronous motor, a PWM inverter for driving the 3-phase synchronous motor, and a current detector for detecting the phase current of each phase of the 3-phase synchronous motor, and is equipped with a 3-phase alternating current. A method has been proposed in which a PWM inverter is controlled by triangular wave pulse width modulation using a voltage command of each phase of a motor and a triangular wave (carrier) (see, for example, Patent Document 1). In this drive device, the phase current of each phase is detected at least once on the upstream side and the downstream side of the triangular wave. As a result, the error included in the detected current can be reduced.

Japanese Unexamined Patent Publication No. 2012-110074

However, in the above-mentioned drive device, it is possible that the current detection error cannot be sufficiently reduced due to the deviation between the center of the current ripple and the current detection timing due to the influence of the switching element switching of the PWM inverter and the dead time. There is.

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

The drive device of the present invention
With a three-phase AC motor
An inverter that drives the three-phase AC motor by switching a plurality of switching elements,
A control device that switches and controls 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.
It is a drive device equipped with
The control device detects the phase current of each phase of the three-phase AC motor at two timings, that is, the timing after the delay time from the peak of the triangular wave and the timing after the delay time from the valley of the triangular wave.
Further, when the control device is in a two-phase modulation mode in which switching of the switching element of one of the three phases of the inverter is stopped and the switching element of the remaining two phases is switched, the two timings are described. The delay time is set so that the difference between the phase currents of the respective phases or the difference between the d-axis and q-axis currents based on the phase currents of the respective phases at the two timings becomes small.
The gist is that.

In the drive device of 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 peak of the triangular wave and the timing after the delay time from the valley of the triangular wave. Then, in the two-phase modulation mode in which the switching of the switching element of one of the three phases of the inverter is stopped and the switching element of the remaining two phases is switched, the difference between the phase currents of each phase at the two timings or 2 The delay time is set so that the difference between the d-axis and q-axis currents based on the phase currents of each phase at one timing becomes small. In the two-phase modulation mode, the inventors make the frequency of the triangular wave and the frequency of the main component of the current ripple of the phase current of each phase the same, and with respect to the phase current (actual value) at the timing of the peak and valley of the triangular wave. The phase currents (detected values) are offset to the opposite sides, and the phase currents (detected values) are offset to the opposite sides with respect to the phase currents (actual values) even at the timing after the delay time from the peaks and valleys of the triangular wave. I found. Therefore, 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 d-axis and q-axis currents of the two timings becomes small, the phase current of each phase of the motor is current rippled. 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 such a driving device of the present invention, when the control device is in the two-phase modulation mode, the difference between the phase currents of the respective phases at the two timings or the currents of the d-axis and the q-axis at the two timings. The delay time may be set so that the difference is minimized. In this way, the phase current of each phase of the motor can be detected further near the center of the current ripple.

In the drive device of the present invention, in the two-phase modulation mode, the control device has a dq-axis current peak / valley difference based on the difference between the d-axis current and the q-axis current at the two timings. Is executed while changing the delay time, and the process of saving the combination of the delay time and the dq-axis current peak / valley difference is executed, and among the plurality of combinations of the delay time and the dq-axis current peak / valley difference. The delay time may be set so that the difference between the dq-axis current peaks and valleys is the minimum. In this way, the delay time can be set more appropriately using the dq-axis current peak / valley difference.

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

In the drive device of the present invention, in the two-phase modulation mode, the control device switches the stop phase for stopping the switching of the switching element by 120 degrees of the electric angle, and turns on the upper arm of the upper and lower arms of the stop phase. It may be fixed. Further, in the two-phase modulation mode, the control device may switch the stop phase for stopping the switching of the switching element by 120 degrees of the electric angle and fix the lower arm of the upper and lower arms of the stop phase on. good. Further, in the two-phase modulation mode, the control device switches the stop phase for stopping the switching of the switching element by 60 degrees of the electric angle and the upper arm of the upper and lower arms of the stop phase by 60 degrees of the electric angle. The on-fixing of the lower arm and the on-fixing of the lower arm may be alternately performed.

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, the "learning condition" is a condition in which a predetermined time has passed since the previous learning of the delay time, a condition in which the amount of fluctuation in the torque of the three-phase AC motor and the amount of fluctuation in the rotation speed are equal to or less than each threshold, and each. Conditions such as a condition in which the amplitude of the phase voltage command is smaller than the amplitude of the triangular wave are used.

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

Next, a mode for carrying out the present invention will be described with reference to examples.

FIG. 1 is a configuration diagram showing an outline of a configuration of an electric vehicle 20 equipped with a drive device as an embodiment of the present invention. As shown in the figure, 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 a permanent magnet is embedded and a stator in which a three-phase coil is wound. The motor 32 is connected to a drive shaft 26 in which a rotor is connected to drive wheels 22a and 22b 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 transistors T11 to T16 as six switching elements, and six diodes D11 to D16 connected in parallel to each of the six transistors T11 to T16. Two transistors T11 to T16 are arranged in pairs so as to be on the source side and the sink side with respect to 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 paired with the transistors T11 to T16. Hereinafter, the transistors T11 to T13 will be referred to as an "upper arm", and the transistors T14 to T16 will be referred to as a "lower arm". Therefore, when a voltage is applied to the inverter 34, the electronic control unit 50 adjusts the ratio of the on-time of the paired transistors T11 to T16, so that a rotating magnetic field is formed in the three-phase coil and 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. As described above, the battery 36 is connected to the inverter 34 via the power line 38.

The electronic control unit 50 is configured as a microprocessor centered on a CPU, and includes a ROM for storing a processing program, a RAM for temporarily storing data, and an input / output port in addition to the CPU. Signals from various sensors are input to the electronic control unit 50 via input ports. The signals input to the electronic control unit 50 include, for example, the rotation position θm of the rotor of the motor 32 from the rotation position detection sensor (for example, resolver) 32a attached to the rotor of the motor 32, and the motor 32 and the inverter 34. The signals from the current sensors 32u, 32v, 32w attached to the power lines of each phase connected to and can be mentioned. Further, the voltage VH of the capacitor 39 (power line 38) from the voltage sensor 39a attached between the terminals of the capacitor 39, the voltage Vb of the battery 36 from the voltage sensor (not shown) attached between the terminals of the battery 36, and the battery. The current Ib of the battery 36 from a current detection unit (not shown) attached to the output terminal of the 36 can also be mentioned. Further, 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, from the accelerator opening Acc from the accelerator pedal position sensor 64 that detects the amount of depression of the accelerator pedal 63, the brake pedal position BP from the brake pedal position sensor 66 that detects the amount of depression 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 current sensors 32u, 32v, 32w into phase currents Iu, Iv, Iw (digital values) of each phase of the motor 32. From the electronic control unit 50, a switching control signal or the like to the transistors T11 to T16 of the inverter 34 is output via the output port. The electronic control unit 50 calculates the electric angle θe and the rotation speed Nm of the motor 32 based on the rotation position θm of the rotor of the motor 32 from the rotation position detection sensor 32a.

In the electric vehicle 20 of the embodiment configured in this way, the required torque Td * required for the drive shaft 26 is set based on the accelerator opening degree 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) so that the motor 32 is driven by the torque command Tm *.

Here, the control of the inverter 34 will be described. First, the electronic control unit 50 uses the electric angle θe of the motor 32 to convert the U-phase, V-phase, and W-phase phase currents Iu, Iv, and Iw into the d-axis and q-axis currents Id and Iq (three-phase). -2 phase conversion). Subsequently, the d-axis and q-axis current commands Id * and Iq * are set based on the torque command Tm * of the motor 32, and the d-axis and q-axis current commands Id * and Iq * and the currents Id and Iq are used. Set the d-axis and q-axis voltage commands Vd * and Vq *. Then, using the electric angle θe of the motor 32, the voltage commands Vd * and Vq * on the d-axis and q-axis are coordinate-converted to the voltage commands Vu *, Vv *, Vw * of each phase (2-phase-3 phase conversion). , 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). When the PWM signals of the transistors T11 to T16 are generated in this way, 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, particularly, the phase currents Iu, Iv, Iw of each phase of the motor 32 are detected, specifically, the current sensor 32u, The operation when converting the signals (analog values) from 32v and 32w into the phase currents Iu, Iv and Iw (digital values) of each phase 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 an interrupt process at each timing of the peak and valley of the triangular wave. As the frequency (carrier frequency) fc of the triangular wave, for example, 4 kHz, 5 kHz, 6 kHz, or the like is used.

When the phase current detection routines of FIGS. 2 and 3 are executed, the electronic control unit 50 waits for the current detection delay time ΔT to elapse, that is, after the current detection delay time ΔT of the peaks and valleys of the triangular wave ( Step S100), the phase currents Iu, Iv, Iw of each phase of the motor 32 are detected. Convert to Iw (digital value) (step S110). Then, the phase currents Iu, Iv, and Iw of each phase are coordinate-converted (three-phase to two-phase conversion) to the d-axis and q-axis currents Id and Iq using the electric angle θe of the motor 32 (step S120). Here, as the current detection delay time ΔT, the time set by the process described later is used. Further, when the d-axis and q-axis currents Id and Iq are set, the transistor of the inverter 34 is controlled by PWM based on the d-axis and q-axis currents Id and Iq as described above by a routine different from this routine. Switching control of T11 to T16 is performed.

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

When 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 terminated. Here, the three-phase modulation mode is a mode for switching the three-phase transistors of the inverter 34 (all of the transistors T11 to T16). FIG. 4 is an explanatory diagram showing an example of voltage commands Vu *, Vv *, Vw * in the three-phase modulation mode, a triangular wave, and a switching signal of each phase. The switching signal of each phase corresponds to the PWM signal of the upper arm of each phase (the PWM signal of the lower arm is inverted on and off). The actual switching of the transistors T11 to T16 is performed based on the PWM signal (switching signal) of the transistors T11 to T16 in consideration of the switching delay and the dead time of the transistors T11 to T16.

When 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 phase transistor (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 and W) are stopped. This mode switches the phase transistors T12, T13, T15, T16). One phase (hereinafter, referred to as “SW stop phase”) for stopping transistor switching is determined based on the electric angle θe of the motor 32. FIG. 5 is an explanatory diagram showing an example of voltage commands Vu *, Vv *, Vw * in a two-phase modulation mode, a triangular wave, and a switching signal of each phase. 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 electric angle θe, and the upper arm of the SW stop phase is fixed on (the lower arm is fixed off). bottom. The reason for setting the two-phase modulation mode will be described later.

Subsequently, it is determined whether or not all the inspections of the candidates for the current detection delay time ΔT have been completed (steps S150 and S152). Here, as a candidate for the current detection delay time ΔT, for example, when the period of the triangular wave is about 200 msec (carrier frequency is about 5 kHz), 1 μsec, 2 μsec, and the like can be mentioned.

When it is determined in steps S150 and S152 that all the inspections of the candidates for the current detection delay time ΔT have not been completed, the interrupt processing (execution of this routine) this time is one of the peak timing and the valley timing of the triangular wave. It is determined which timing of the interrupt processing is (step S160). Then, when it is determined that the interrupt processing this time is the interruption processing of the timing of the peak of the triangular wave, the d-axis and q-axis currents Id and Iq calculated in step S120 are the d-axis and q-axis currents (peaks). When Ida and Iqa are set (step S170) and it is determined that the interrupting process this time is the interrupting process of the timing of the valley of the triangular wave, the currents Id and Iq of the d-axis and q-axis are of the d-axis and q-axis. The currents (valleys) are set to Idb and Iqb (step S180).

Subsequently, it is determined whether or not the data of the d-axis and q-axis currents (peaks) Ida and Iqa and the currents (valleys) Idb and Iqb are aligned (step S190). End the routine.

When it is determined in step S190 that the d-axis and q-axis currents (peaks) Ida and Iqa and the current (valley) Idb and Idq data are complete, the currents from the d-axis and q-axis currents (mountains) Ida and Iqa are present. (Valley) Idb and Idq are subtracted to calculate the current peak / valley difference ΔId and ΔIq on the d-axis and q-axis (step S200). The dq-axis current peak / valley difference ΔIdq is calculated as the square root of the sum with the square (step S210).

Then, it is determined whether or not the dq-axis current peak / valley difference ΔIdq can be filtered (annealed) (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 since the current detection delay time ΔT was set to the current value. When it is determined that the dq-axis current peak / valley difference ΔIdq cannot be filtered, this routine is terminated as it is.

When it is determined in step S220 that the dq-axis current peak / valley difference ΔIdq can be filtered (annealed), the dq-axis current peak / valley difference ΔIdq is filtered (annealed). The dq-axis current peak / valley difference (filter value) ΔIdq is calculated (step S230). This process is performed, for example, by performing a smoothing process on the dq-axis current peak / valley difference ΔIdq using a predetermined time Δtf as a time constant.

Next, the timer value Tti as the elapsed time after selecting the candidate for the current detection delay time ΔT is compared with the predetermined time Tiref (step S240). Here, the predetermined time Ttilef is a time required to determine whether or not the dq-axis current peak / valley difference (filter value) ΔIdqf is stable, and is defined as a time sufficiently longer than the predetermined time Δtf, for example. A time such as 5 times, 7 times, or 10 times the predetermined time Δtf is used. When the timer value Tti is less than Ttiref for a predetermined time, this routine is terminated as it is.

When the timer value Tti is equal to or longer than the predetermined time Ttiref in step S240, the combination of the current detection delay time ΔT and the dq-axis current peak / valley difference (filter value) ΔIdqf is saved (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, when the current detection delay time ΔT is 1 μsec, the dq-axis current peak / valley difference (filter value) ΔIdqf is 20 A and the current. 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 the uninspected candidates of the current detection delay time ΔT (step S260), the timer value Tti is reset to the value 0, and then the timing is started (step S270). End this routine. When there are no uninspected candidates among the candidates for the current detection delay time ΔT, the current current detection delay time ΔT is reselected.

When there are no uninspected candidates among the candidates for the current detection delay time ΔT in step S260, all the inspections for the candidates for the current detection delay time ΔT are completed in steps S150 and S152 the next time this routine is executed. (There are no uninspected candidates), and the current detection with the smallest dq-axis current peak / valley difference (filter value) ΔIdqf among the multiple combinations of the current detection delay time ΔT and the dq-axis current peak / valley difference (filter value) ΔIdqf. The delay time ΔT is selected and set (step S280), and this routine ends. When the current detection delay time ΔT is set in this way, when this routine is executed from the next time onward, 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 * in one cycle of the triangular wave in the three-phase modulation mode, the switching signal of the triangular wave and each phase, and the phase current (actual value) of the voltage Vu, Vv, Vw and the U phase. It is explanatory drawing which shows Iuact and phase current (detection value) Iu. FIG. 7 shows the voltage commands Vu *, Vv *, Vw * in one cycle of the triangular wave in the two-phase modulation mode, the switching signal of the triangular wave and each phase, and the phase current (actual value) of the voltage Vu, Vv, Vw and the U phase. It is explanatory drawing which shows Iuact and phase current (detection value) Iu. In FIGS. 6 and 7, the hatched portion is a phase voltage delay with respect to the switching signal of each phase due to a switching delay of the transistor of each phase, a dead time, or the like. 6 and 7 show the case where the U-phase phase current (actual value) Euact is positive. Further, the circles of the U-phase phase current (detected value) Iu in FIGS. 6 and 7 are the phase currents (detected values) Iu of the timing of the peaks and valleys of the triangular wave, and the triangular marks are the peaks and valleys of the triangular wave. It is the phase current (detection value) Iu of the timing after the delay time ΔTa.

In the three-phase modulation mode, as can be seen from FIG. 6, the main components of the current ripple of the phase current (actual value) Iuact and the phase current (detection value) Iu are 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) even at the timing after the delay time ΔTa from the peak and valley of the triangular wave. ) The phase current (detected value) Iu is offset to the same side (larger side) with respect to Iuact. Therefore, it is difficult to appropriately set the current detection delay time ΔT.

On the other hand, in the two-phase modulation mode, as shown in FIG. 7, the main components of the current ripples of the phase current (actual value) Iuact and the phase current (detection value) Iu have the same frequency as the triangular wave, and the triangular wave At the timing of peaks and valleys, the phase current (detected value) Iu is offset to the opposite side with respect to the phase current (actual value) Iuact, and even at the timing after the delay time ΔTa from the peaks and valleys of the triangular wave, the phase current (actual value) The phase current (detected value) Iu is offset to the opposite side with respect to the value) Iuact. Therefore, the delay time that minimizes 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. If ΔTa is set to the current detection delay time ΔT in the process of step S280, the U-phase phase current Iu can be detected near the center of the current ripple. In the embodiment, based on this, the dq-axis current peak / valley difference (filter value) ΔIdqf is calculated using the d-axis and q-axis currents Id and Iq based on the phase currents Iu, Iv, and Iw of each phase, and the current is detected. The relationship between the delay time ΔT and the dq-axis current peak / valley difference (filter value) ΔIdqf was obtained, and the current detection delay time ΔT at which the dq-axis current peak / valley difference (filter value) ΔIdqf was minimized was selected. As a result, the phase currents Iu, Iv, and Iw of each phase 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, and Iw of each phase can be further reduced.

In the drive device mounted on the electric vehicle 20 of the above-described embodiment, in the two-phase modulation mode, the d-axis and q-axis currents Id and Iq based on the phase currents Iu, Iv and Iw of each phase of the motor 32 The dq-axis current peak / valley difference (filter value) ΔIdqf is calculated using, and the relationship between the current detection delay time ΔT and the dq-axis current peak / valley difference (filter value) ΔIdqf is obtained. Then, the current detection delay time ΔT that minimizes the dq-axis current peak / valley difference (filter value) ΔIdqf is selected. As a result, the phase currents Iu, Iv, and Iw of each phase 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, and Iw of each phase can be further reduced.

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

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

In the drive device mounted on the electric vehicle 20 of the embodiment, the electronic control unit 50 is supposed to execute the phase current detection routine of FIGS. 2 and 3, but instead of this, the phase current detection routine of FIG. May be executed.

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, for the 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. It is converted into currents Iu, Iv, Iw (digital values) (step S310). Here, as the current detection delay times ΔTu, ΔTv, and ΔTw, the times set by the processes described later are used. That is, the current detection delay times ΔTu, ΔTv, and ΔTw are not necessarily the same time. Therefore, the timing of detecting the phase currents Iu, Iv, and Iw of each phase of the motor 32 is not always the same.

Subsequently, it is determined whether or not the learning conditions for the current detection delay times ΔTu, ΔTv, and ΔTw are satisfied (step S320). Here, as the learning conditions, for example, a predetermined time (for example, about several minutes to several tens of minutes) has elapsed since the last learning of the current detection delay times ΔTu, ΔTv, and ΔTw, and the motor A condition in which the rotation speed Nm of 32 is approximately 0 (the absolute value of the rotation speed Nm is equal to or less than the threshold value), and the amplitudes of the voltage commands Vu *, Vv *, and Vw * of each phase are smaller than the amplitude of the triangular wave. Etc. are used. The learning conditions are 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 this routine is terminated.

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 that stops transistor switching) is U-phase, V-phase, or W-phase. Which of these phases is determined (step S350). In this modification, 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) as in the embodiment. (See Fig. 5).

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

Subsequently, it is determined whether or not the data of the phase current (peak) Iua and the phase current (valley) Iub are aligned (step S390), and when it is determined that they are not aligned, this routine is terminated as it is.

When it is determined in step S390 that the data of the phase current (peak) Iua and the phase current (valley) Iub are complete, it is determined whether or not the U-phase phase current Iu 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), and the U-phase phase is calculated. 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 the 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 terminated.

FIG. 11 shows the current detection delay time ΔTu, the phase current (peak) Iua, and the phase current (valley) in the two-phase modulation mode of FIG. 5 when the SW stop phase is the U phase and the phase current Iu of the U phase is positive. It is explanatory drawing which shows an example of the relationship with Iub. Further, FIG. 12 shows the current detection delay time ΔTu, the phase current (mountain) Iua, and the phase current (when the SW stop phase is the U phase and the phase current Iu of the U phase is negative in the two-phase modulation mode of FIG. Tani) It is explanatory drawing which shows an example of the relationship with Iub. The relationship of FIG. 11 is obtained from the relationship between the phase current (actual value) Iuact of the U phase of FIG. 7 and the phase current (detected value) Iu. FIG. 12 can be considered in the same manner as in 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, and in the case of FIG. 12, the phase current (peak) Iua is subtracted from the phase current (valley) Iub. The 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, the U-phase phase current Iu can be detected near the center of the current ripple. Thereby, the detection error of the phase current of each phase can be further reduced.

When 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 and the current detection delay time ΔTw are set (corrected) in the same manner as when it is determined that the SW stop phase is the U phase. Then (steps S440 to S510 or steps S520 to S590), this routine is terminated. Hereinafter, a brief description will be given.

When the SW stop phase is the V phase, when the current interrupt process (execution of this routine) is the interrupt process of the timing of the peak of the triangular wave, the phase current Iv of the V phase is set to the phase current (mountain) Iva. Then, when the interrupt processing this time is the interruption processing of 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 (mountain) Iva and the phase current (valley) Ivb are available (step S470), when the phase current Iv of the V phase is positive, the phase current (mountain) Iva to the phase current The V-phase current deviation ΔIv is calculated by subtracting the (valley) Ivb, and when the V-phase phase current Iv is not positive, the phase current (peak) Iva is subtracted from the phase current (valley) Ivb to calculate the V-phase current deviation ΔIv. (Steps S480-S500). When the V-phase current deviation ΔIv is calculated in this way, the current detection delay time ΔTv is set (corrected) by feedback control so that the V-phase current deviation ΔIv becomes a value 0 (step S510), and this routine is terminated.

When the SW stop phase is the W phase, when the current interrupt process (execution of this routine) is the interrupt process of the peak timing of the triangular wave, the phase current Iw of the W phase is set to the phase current (mountain) Iwa. Then, when the interrupt processing this time is the interrupt processing of 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 (mountain) Iwa and the phase current (valley) Iwb are available (step S550), when the phase current Iw of the W phase is positive, the phase current (mountain) Iwa to the phase current The W-phase current deviation ΔIw is calculated by subtracting the (valley) Iwb, and when the W-phase phase current Iw is not positive, the W-phase current deviation ΔIw is calculated by subtracting the phase current (peak) Iwa from the phase current (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 terminated.

As described above, in 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). Based on this, after starting the learning of the current detection delay times ΔTu, ΔTv, and ΔTw (after starting the two-phase fixed mode), the motor 32 rotates by a predetermined cycle (for example, about several cycles) at the electric angle θe. When the current detection delay time ΔTu, ΔTv, ΔTw set in steps S430, S510, and S590 is stable (when the fluctuation amount is equal to or less than the predetermined amount over a predetermined time), the current is detected. It is conceivable to end the learning of the delay times ΔTu, ΔTv, and ΔTw. After learning the current detection delay times ΔTu, ΔTv, and ΔTw in this way, when this routine is executed from the next time onward, the current detection delay times ΔTu, ΔTv, and ΔTw will be set until the next learning condition is satisfied. Used (held).

In this modification, as the two-phase modulation mode, as shown in FIG. 5, 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). I made it. 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 phase current Iu of the U phase 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 the U phase and the phase current Iu of the U phase is negative is as shown in FIG. become.

However, as a two-phase modulation mode, as shown in FIG. 8, the SW stop phase may be switched by 120 degrees of the electric angle θe and the lower arm of the SW stop phase may be fixed on (the upper arm shall be 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 phase current Iu of the U phase 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 the U phase and the phase current Iu of the U phase 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 is calculated from the phase current (peak) Iua. The U-phase current deviation ΔIu may be calculated by subtracting the current, and the current detection delay time ΔTu may be set by feedback control so that the U-phase current deviation ΔIu becomes a value of 0. In this way, the U-phase phase current Iu can be detected near the center of the current ripple, and the phase current detection error of each phase can be further reduced. Similarly, 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.

Further, as a two-phase modulation mode, as shown in FIG. 9, the SW stop phase is switched by 60 degrees of the electric angle θe, and the upper arm of the SW stop phase is fixed on (fixed off of the lower arm) by 60 degrees of the electric angle θe. ) And on-fixing of the lower arm (off-fixing 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. 11 or FIG. When the SW stop phase is the U phase and the lower 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. 13 or It becomes as shown in FIG. Therefore, the U-phase current deviation ΔIu may be calculated according to which of FIGS. 11 to 14 corresponds to, and the current detection delay time ΔTu may be set by feedback control so that the U-phase current deviation ΔIu becomes a value of 0. .. In this way, the U-phase phase current Iu can be detected near the center of the current ripple, and the phase current detection error of each phase can be further reduced. Similarly, 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.

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

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

In the embodiment, the drive device is mounted on the electric vehicle 20 including the motor 32. However, it may be in the form of a drive device mounted on a hybrid vehicle including an engine in addition to the motor 32, or may be in the form of a drive device mounted on a moving body such as a vehicle, a ship, or an aircraft other than the automobile. 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 examples and the main elements of the invention described in the column of means for solving the problem will be described. In the embodiment, the motor 32 corresponds to the "three-phase AC motor", the inverter 34 corresponds to the "inverter", and the electronic control unit 50 corresponds to the "control device".

Regarding the correspondence between the main elements of the examples and the main elements of the invention described in the column of means for solving the problem, the invention described in the column of means for solving the problem in the examples is carried out. Since it is an example for specifically explaining the form for solving the problem, the elements of the invention described in the column of means for solving the problem are not limited. That is, the interpretation of the invention described in the column of means for solving the problem should be performed based on the description in the column, and the examples are the inventions described in the column of means for solving the problem. It is just a concrete example.

Although the embodiments for carrying out the present invention have been described above with reference to examples, the present invention is not limited to these examples, and various embodiments are used without departing from the gist of the present invention. Of course, it can be done.

The present invention can be used in the driving device manufacturing industry and the like.

20 electric vehicle, 22a, 22b drive wheel, 24 differential gear, 26 drive shaft, 32 motor, 32a rotation position detection sensor, 32u, 32v, 32w current detector, 34 inverter, 36 battery, 38 power line, 39 condenser, 39a Voltage sensor, 50 electronic control unit, 60 ignition switch, 61 shift lever, 62 shift position sensor, 63 accelerator pedal, 64 accelerator pedal position sensor, 65 brake pedal, 66 brake pedal position sensor, 68 vehicle speed sensor, D11 to D16 diode, T11 to T16 transistors.

Claims (1)

With a three-phase AC motor
An inverter that drives the three-phase AC motor by switching a plurality of switching elements,
A control device that switches and controls 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.
It is a drive device equipped with
The control device detects the phase current of each phase of the three-phase AC motor at two timings, that is, the timing after the delay time from the peak of the triangular wave and the timing after the delay time from the valley of the triangular wave.
Further, when the control device is in a two-phase modulation mode in which switching of the switching element of one of the three phases of the inverter is stopped and the switching element of the remaining two phases is switched, the two timings are described. The delay time is set so that the difference between the phase currents of the respective phases or the difference between the d-axis and q-axis currents based on the phase currents of the respective phases at the two timings becomes small.
Drive device.

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