JP2002223590A - Drive control device for ac motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suitably switch an AC motor, in response to the state of the motor in a driver of the AC motor for switching a PWM current control mode and a rectangular wave voltage control mode. SOLUTION: Switching of a PWM current control to a rectangular wave voltage control is carried out, based on a decision result of a voltage amplitude decision unit 16, and switching of the rectangular wave voltage control to the PWM current control is carried out, based on a decision result of a current phase decision unit 22. A current phase used in the unit 22 is used, based on a mean value of current phases sampled at switching timing of the rectangular voltage in the rectangular wave voltage control mode and with its intermediate timing. The unit 22 decides, based rather not on the current phase but on the amplitude of a d-axis component of the current vector on a d-q axis, when the current amplitude is small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control apparatus for an AC motor, and more particularly to a technique for driving an AC motor by selectively using pulse width modulation (PWM) current control and rectangular wave voltage control.

[0002]

2. Description of the Related Art An inverter is used to drive an AC motor using a DC power supply, and the inverter is controlled by an inverter drive circuit. Generally, pulse width modulation (PWM) is used for switching control.

A PWM for applying a PWM waveform to an AC motor
The current control has an advantage that a smooth rotation can be obtained even in a low rotation range, but has a problem that the voltage utilization rate of the DC power supply is limited.

On the other hand, in the rectangular wave control method for applying a rectangular wave voltage to an AC motor, it is possible to improve the voltage utilization rate of a DC power supply, and thus to improve the output in a high rotation range.

For this reason, conventionally, both a PWM control and a rectangular wave voltage control can be applied to an AC motor, and these can be selectively used depending on the situation, and the output of the motor particularly in a high rotation range is improved. A configuration has been proposed.

[0006]

However, in the rectangular wave voltage control, the torque of the AC motor is detected, and the rectangular wave voltage is controlled so that the detected torque value matches a torque command value determined according to the accelerator opening and the like. And it is premised that the output torque of the AC motor is detected with high accuracy. In the rectangular wave voltage control, the phase of the rectangular wave voltage is controlled and supplied to the AC motor, and the current value to the AC motor fluctuates according to the switching of the rectangular wave voltage, so that it has a harmonic component. Therefore, there is a problem that an accurate output torque cannot be detected in a configuration in which a current and a voltage are sampled at a predetermined timing and the electric power and the torque of the AC motor are detected based on the current and the voltage.

The switching between the PWM current control and the rectangular wave voltage control is executed based on the voltage amplitude and the current phase supplied to the AC motor. More specifically, the switching from the PWM current control to the rectangular wave voltage control is performed. The control is performed based on the voltage amplitude, and the switching from the rectangular wave voltage control to the PWM control is performed based on the current phase. However, as described above, since the current includes a harmonic component, the current phase is sampled at a certain timing. In such a case, there is a problem that the current phase cannot be detected with high accuracy, and thus accurate switching cannot be performed.

Further, when detecting the current phase, if the amplitude of the current is small, the influence of noise is large and the phase fluctuates greatly. Therefore, particularly when the current amplitude is small, switching from the rectangular wave voltage control to the PWM current control is performed. Was not performed properly.

Further, when the control is switched based on the voltage amplitude or the current phase, it is premised that the inverter operates and can detect these. For example, an AC motor is used in an electric vehicle (EV) or a hybrid vehicle (HV). When the vehicle driver shifts the shift position from the D range to the N range while driving, the control device of the vehicle shuts off the inverter gate and stops the operation, so that the voltage amplitude and the current phase can be detected. Therefore, when the vehicle driver shifts from the N range to the D range again, there is a problem that smooth switching is not performed and drivability is reduced.

The present invention has been made in view of the above-mentioned problems of the related art, and has as its object to execute rectangular wave voltage control with high accuracy and to appropriately switch between PWM current control and rectangular wave voltage control. It is an object of the present invention to provide a device which can be performed on a computer.

[0011]

In order to achieve the above object, the present invention provides a PWM current control means for outputting a sine wave current having a predetermined amplitude and a predetermined phase according to a torque command, and a rectangular current control means according to the torque command. A drive control device for an AC motor, comprising: a rectangular wave voltage control unit that outputs a wave voltage; and a switching unit that switches between the output of the PWM current control unit and the output of the rectangular wave voltage control unit and supplies the output to the AC motor. Wherein the rectangular wave voltage control means detects a current and an output voltage to the AC motor at a predetermined timing;
Means for calculating the power at each timing based on the detected current and voltage; means for averaging the power at each calculated timing; and calculating the output torque of the AC motor based on the averaged power. And means for performing the operation. Even if a current fluctuation occurs due to the switching of the rectangular wave voltage in the rectangular wave voltage control, by averaging the power values obtained at a predetermined timing, it is possible to remove a higher-order component and accurately detect torque. .

Here, it is preferable that the predetermined timing is a switching timing of the rectangular wave voltage and an intermediate timing between the switching timings.

In the present invention, the averaging means includes:
It can be configured to include a low-pass filter.

Further, the present invention provides a PWM current control means for outputting a sine wave current having a predetermined amplitude and a predetermined phase according to a torque command, a rectangular wave voltage control means for outputting a square wave voltage according to a torque command, A drive control device for an AC motor having switching means for switching between the output of the PWM current control means and the output of the rectangular wave voltage control means and supplying the output to the AC motor, wherein the switching means supplies the AC motor with Means for detecting the phase of the current at a predetermined timing, and means for averaging the detected current phase, and switching is performed according to the averaged current phase. By averaging the current phases obtained at a predetermined timing, the current phase can be accurately detected, and thereby the switching timing can be optimized.

Here, it is preferable that the predetermined timing is a switching timing of the rectangular wave voltage and an intermediate timing between the switching timings.

In the present invention, the averaging means includes:
It can be configured to include a low-pass filter.

Also, the present invention provides a PWM current control means for outputting a sine wave current having a predetermined amplitude and a predetermined phase according to a torque command, a rectangular wave voltage control means for outputting a rectangular wave voltage according to a torque command, A drive control device for an AC motor having switching means for switching between the output of the PWM current control means and the output of the rectangular wave voltage control means and supplying the output to the AC motor, wherein the switching means supplies the AC motor with And a region determining means for determining whether or not the current vector is located within a predetermined region, and switching is performed based on the determination. By performing the switching based on the positional relationship between the current vector and the region, the switching can be performed more stably with respect to the phase fluctuation due to noise than when switching is performed only by the current phase.

Here, the judging means has absolute value judging means for judging whether or not the magnitude of the current vector is equal to or larger than a predetermined value, wherein the magnitude of the current vector is equal to or larger than a predetermined value. In this case, the switching can be performed based on the phase of the current vector, and when the magnitude of the current vector is smaller than a predetermined value, the switching can be performed based on the determination by the area determination unit. When the magnitude of the current vector is relatively small, the phase fluctuation due to noise increases. Therefore, in this case, the switching can be stably performed by determining not the current phase but the positional relationship between the current vector and the region.

In the present invention, the area determination means can make the determination based on a d-axis component of the current vector on a dq plane. If the region is asymmetric with respect to the q-axis, more specifically in the negative region of the d-axis,
Whether or not the current vector is within the region can be determined based on the d-axis component of the current vector.

Also, the present invention provides a PWM current control means for outputting a sine wave current having a predetermined amplitude and a predetermined phase according to a torque command, a rectangular wave voltage control means for outputting a square wave voltage according to a torque command, A drive control device for an AC motor having switching means for switching between the output of the PWM current control means and the output of the rectangular wave voltage control means and supplying the output to the AC motor, wherein the switching means There is provided a means for detecting a back electromotive voltage, and a means for comparing the back electromotive voltage with an input voltage of an inverter for driving the AC motor, and switching is performed based on the comparison. When the inverter is in a stopped state, switching cannot be performed based on the voltage amplitude, the current phase, and the current vector. On the other hand, when the rotation speed of the AC motor is high, the back electromotive voltage also increases. Therefore, the control mode can be switched by detecting the back electromotive voltage as a parameter for evaluating the rotation speed of the AC motor, and using the reverse voltage and the input voltage of the inverter. The comparison between the back electromotive voltage and the input voltage of the inverter can be executed, for example, by calculating the ratio between the back electromotive voltage and the input voltage of the inverter.

Here, the means for detecting includes means for calculating a rotational speed based on a signal from a resolver provided in the AC motor, and means for calculating the back electromotive voltage based on the rotational speed. Can have.

Further, in the present invention, there is provided means for detecting a stop state of the inverter, and the switching means can switch when the inverter is in a stop state.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a basic configuration of a drive control device for an AC motor according to this embodiment. The drive control device 10 is mounted on, for example, an electric vehicle EV, and has two control modes: a PWM current control mode and a rectangular wave voltage control mode.

In the PWM current control mode, switch 2 in FIG.
8 is switched to the upper side, the current value of the alternating current output from the inverter 36 is fed back to the current controller 14, and the current value is the command value | I | The voltage amplitude | V | and the voltage phase ψ are set so as to approach the command value φ, and a sine wave voltage is output to the AC motor 38 by the PWM circuit 30 and the inverter 36.

The rectangular wave voltage control mode is a control mode executed when the switch 28 is switched to the lower side in the figure. In this mode, a rectangular wave voltage is applied to the motor 38. The amplitude | V | of the rectangular wave voltage is determined by the battery voltage of the inverter 36, and is always constant. Further, the voltage phase ψ is set according to the torque command value.

When a vehicle driver operates an accelerator or a brake, an electronic control unit (ECU) (not shown) generates a torque command value in accordance with the accelerator opening and the brake depression angle. 12 and adder 1
3 and output. The current command generator 12 generates a current amplitude | I | and a current phase φ based on the input torque command value. The current controller 14 performs a proportional-integral control to generate a voltage amplitude | V | and a voltage phase ψ. Note that the voltage phase ψ is defined by the angle of a voltage vector with respect to the q axis in the dq plane. The generated voltage amplitude | V | and the voltage phase ψ are supplied to the PWM circuit 30. Although not shown, a current value is fed back from the current sensor 40 to the current controller 14, and the current controller 14 generates an amplitude and a phase based on the feedback current value.

In the PWM circuit 30, a switching signal is generated by comparing a sine wave having a voltage amplitude | V | and a voltage phase ψ supplied from the current controller 14 with a predetermined triangular wave. The switching signal is supplied to the inverter 36 via the switch 28. The inverter 36 is a voltage type inverter, generates a sine wave voltage based on the switching signal supplied from the PWM circuit 30,
8 to drive the motor 38 to rotate.

The motor 38 is a permanent magnet synchronous (PM) motor, and a current sensor 40 is provided on a current supply line of the motor 38 from the inverter 36. The actual current phase φi detected by the current sensor 40 is the current phase determination unit 2
2 is supplied.

On the other hand, the torque command value generated by the ECU is also supplied to the adder 13 as described above. Adder 13
Is also input with the torque value detected by the torque detection unit 20, and the adder 13 generates a torque deviation ΔT, which is the difference between the two. The torque detector 20 detects the torque by executing the following calculation.

[0031]

T = Pin / ω = (iu × vu + iv × vv + iw × vw) / ω (1) where Pin is the power supplied to the motor 38 and ω
Is the angular velocity of the motor 38, iu, iv, iw are the motor 38
, V-phase, and W-phase current values, vu, vv,
vw indicates the voltage values of the U-phase, V-phase, and W-phase supplied to the motor 38, respectively. These are detected by the current sensor 40 and the voltage sensor, and the torque T is calculated according to the above equation. The calculation timing of the electric power Pin, that is, the sampling timing of the current and the voltage will be described later.

The torque deviation ΔT generated by the adder 13 is supplied to the voltage phase controller 18. Voltage phase controller 18
Generates a voltage phase ψ according to the torque deviation ΔT. This voltage phase ψ is the phase of the rectangular wave applied to the motor 38.

In the rectangular wave generator 32, the voltage phase controller 1
A switching signal is generated so as to generate a rectangular wave voltage based on the voltage phase ψ supplied from 8. The switching signal is supplied to the inverter 36 via the switch 28, and the inverter 36 supplies a rectangular wave voltage to the motor 38 based on the switching signal to drive the motor 38 to rotate.

The switch 28 is switched by the voltage amplitude determination unit 1
6 and the signal from the current phase determining unit 22. The voltage amplitude determining unit 16 determines that the drive control device 10
Current controller 1 when operating in WM current control mode
4 determines whether the voltage amplitude | V | supplied to the PWM circuit 30 is equal to or greater than a predetermined voltage amplitude V0. If the voltage amplitude | V | is equal to or greater than the predetermined voltage amplitude V0, the switch 28 is switched to the lower side to perform PWM. The mode is switched from the current control mode to the rectangular wave voltage control mode. When the drive control device 10 is operating in the rectangular wave voltage phase control mode, the current phase determination unit 22 determines that the absolute value of the phase φi of the alternating current supplied from the inverter 36 to the motor 38 is equal to the predetermined current phase φ0. If the current phase is less than φ0, the switch 28 is switched to the upper side to switch from the rectangular wave voltage control mode to P.
Shift to the WM current control mode.

FIG. 2 shows the U-phase supplied to the motor 38,
The V-phase and W-phase rectangular wave voltages and the U-phase current are shown.
In the rectangular wave control mode, the motor 38 is driven by controlling the phase of each phase of the rectangular wave voltage, and the current value fluctuates at the rectangular wave voltage switching timing. Therefore,
For example, in the configuration in which the current is sampled by the current sensor 40 in synchronization with the switching timing of the rectangular wave voltage, the peak time of the power calculated by the product of the current and the voltage of each phase is calculated as shown in FIG. A power value larger than the original power value will be obtained. Of course, it is conceivable to adopt a value obtained by subtracting the offset from such a power value, but how to set the offset value is problematic.

Therefore, in this embodiment, in addition to the above-described rectangular wave voltage switching timing (black circles in FIG. 2), the intermediate timing between the switching timings is used as the current and voltage sampling timings for calculating the torque. (White circle in Fig. 2)
By averaging the power values calculated at these two timings, highly accurate torque detection is possible.

FIG. 3 is a block diagram showing the configuration of the torque detector 20 in this embodiment. Current sensor 4
The current value and the voltage value are detected by the 0 and the voltage detector 20a, respectively, and the current value and the voltage value sampled at the switching timing of the rectangular wave voltage and at the intermediate timing of the switching timing are sequentially supplied to the power calculator 20b. The power calculator 20b calculates the product of the input current value and voltage value,
The power value at that timing is calculated and the averaging unit 20
c. For the calculation of the power, refer to equation (1). The averaging unit 20c calculates an average (P0 + P1) / 2 of the power value P0 at the switching timing and the power value P1 at an intermediate timing between the switching timings,
The electric power of the motor 38 is supplied to the torque calculator 20d. The torque calculator 20d divides the calculated electric power by the angular velocity of the motor 38 based on the equation (1), and
Is supplied to the rectangular wave voltage controller 19.

The rectangular wave voltage controller 19 includes the adder 13, the voltage phase controller 18, and the rectangular wave generator 3 in FIG.
2 and the switch 28.

FIG. 4 shows a flowchart of the torque detecting process in the torque detecting section 20 described above. First, it is determined whether or not it is a rectangular wave voltage switching timing (S101). If it is the switching timing, the current value detected by the current sensor 40 and the voltage detected by the voltage detector 20a are sampled ( (S102), the power P0 at the rectangular wave voltage switching timing is calculated using the sampled current value and voltage value (S103). Next, it is determined whether or not the timing is the intermediate timing of the switching timing of the rectangular wave voltage (S104). If the timing is the intermediate timing, the detected current value and voltage value are sampled (S105). Is calculated (S106). The power at the switching timing and the intermediate timing of the rectangular wave voltage is supplied to the averaging unit 20c, and the averaging unit 20c calculates the average value P (S107). The averaged power value P is supplied to the torque calculator 20d as the power value of the motor 38, and the torque calculator 20d calculates the torque of the motor 38 based on the power value and the angular velocity ω of the motor 38 (S108).

As described above, in the present embodiment, the detected current value and voltage value are sampled at two timings of the switching timing and the switching timing to calculate the power.
By averaging the power, an accurate torque value can be calculated.

In this embodiment, the current value and the voltage value are sampled at the switching timing of the rectangular wave voltage and at an intermediate timing between the switching timings, the power is calculated, and the average value of both is calculated. Instead of sampling at the timing, the averaging process is equivalently performed by making the sampling period shorter than 1/12 of the electric period and passing through a low-pass filter to remove harmonic components that are 6 times or more the electric frequency. It can be performed.

FIG. 5 is a block diagram showing the configuration in such a case. As the torque detecting section 20, a low-pass filter LPF 20e is provided instead of the averaging section 20c. The current and voltage detected by the current sensor 40 and the voltage detector 20a are multiplied by the power calculator 20b,
Power is calculated. The calculated electric power is supplied to the low-pass filter 20e, where the higher-order components are removed, and the electric power is supplied to the torque calculator 20d. The power signal from which the higher-order component has been removed shows an almost average value, and the torque calculator 2
In 0d, the torque of the motor 38 is calculated based on the input electric power value and the rotation speed from the rotation speed calculator 42, and is supplied to the rectangular wave voltage controller 19.

As described above, the torque can be detected with high accuracy, and the control in the rectangular wave voltage control mode can be ensured.

Next, detection of a current phase for switching from rectangular wave voltage control to PWM current control will be described.

FIG. 6 is a block diagram showing the configuration when the current phase is detected and the rectangular wave voltage control is switched to the PWM control. As described above, when the current phase is less than the predetermined value, the control is switched from the rectangular wave voltage control to the PWM control.
If the current phase cannot be accurately detected, the switching timing becomes inappropriate. Therefore, the phase of the current detected by the current sensor 40 is averaged, and switching is determined based on the averaged current phase. That is, the switching timing calculated by the current phase calculation unit 44 and the current phase at the intermediate timing between the switching timings are supplied to the averaging unit 46, and the averaging unit 46 averages the respective current phases and sends the averaged current phase to the current phase determination unit 22. Supply.

FIG. 7 shows a processing flowchart in this embodiment. First, it is determined whether or not the rectangular wave voltage is at the phase switching timing (S201). If it is the switching timing, the current detected by the current sensor 40 is sampled, and its phase φi0 is calculated (S203). Next, it is determined whether or not the timing is an intermediate timing of the switching timing (S204). If the timing is the intermediate timing, the current is sampled again at this timing (S205), and the current phase φi1 is calculated (S206). Then, the average (φi0 + φi1) / 2 of the current phase φi0 calculated in S203 and the current phase φi1 calculated in S206 is calculated (S207), and the average value is set as the actual current phase φi in the current phase determination unit 22. To supply.

As described above, the current phase is also determined by averaging the values sampled at two timings, thereby accurately detecting the current phase even if the current component contains a higher-order component. Can be appropriately switched to PWM control.

Also in the above example, instead of sampling at a predetermined timing, the sampling period is made shorter than 1/12 of the electric period, and further transmitted through a low-pass filter to obtain a higher harmonic of 6 times or more the electric frequency. The averaging process can be equivalently performed by removing the components.

Next, another method for switching from the rectangular wave voltage control to the PWM current control will be described.

FIG. 8 shows a driving device 10 according to this embodiment.
Other configurations are shown. In the present embodiment, when switching from the rectangular wave voltage control to the PWM current control, the switching is not performed based on the phase of the current to the motor 38 but is determined based on the positional relationship between the current vector itself and the predetermined area. As described above, when the current amplitude is small, the influence of the noise or current fluctuation of the current sensor 40 on the current phase becomes large, so that the current phase largely changes and control switching frequently occurs, and the control becomes unstable. Therefore, in the present embodiment, the determination is not made based only on the current phase.
The control is switched based on the current vector itself, specifically, both the d component Id and the q axis component Iq of the current vector on the dq axes. This enables more stable switching than before.

In the present embodiment, the current detected by the current sensor 40 is supplied to the current vector area determination section 50. The current vector region determination unit 50 is also supplied with control region map data stored in the control region map storage unit 48 in advance, more specifically, data on a region where rectangular wave voltage control is to be performed on the dq plane. The vector area determination unit 50 compares the current vector detected by the current sensor 40 with the control area map data to determine whether the current vector is within the rectangular wave voltage control area. When it is determined that the current vector is located in the rectangular wave voltage region, specifically, from the current vectors Id and Iq, the switch 28 is set to the lower side to perform the rectangular wave voltage control. If the current vector is out of the area, the switch 28 is switched to the upper side to switch from the rectangular wave voltage control to the PWM current control.

FIG. 9 shows an example of the rectangular wave voltage control area stored in the control area map storage unit 48. A rectangular wave voltage control area (shaded area in the figure) is defined as a predetermined area on the dq plane, and a boundary line indicates a condition to be controlled by the PWM current control. When the current vector is located within the region, the rectangular wave voltage control mode is executed, and otherwise, the PWM control is executed along the boundary.

In the present embodiment, the determination is made based on the current vectors Id and Iq, but it may be determined whether the current vector is within a predetermined area based on the absolute value and phase of the current vector.

Further, in the present embodiment, the control is switched depending on whether or not the current vector is within a predetermined area. However, the control is switched based only on the magnitude of Id of the current vector on the dq plane. It is also possible. That is, in FIG. 9, since the rectangular wave voltage control region exists in the negative region of the d-axis, if Id is negative, there is a possibility that it exists in the rectangular wave voltage sine region, but Id is positive and large. In this case, the current vector does not exist in the rectangular wave voltage control area. Therefore, simply comparing the sign of Id or the magnitude of Id with a threshold value makes it possible to easily determine whether or not the current vector exists in the region.

FIG. 10 shows a processing flowchart in the case of switching using Id. First, it is determined whether the current control is the PWM current control mode or the rectangular wave voltage control mode. If the current mode is the PWM current control mode, the voltage amplitude is compared with the predetermined threshold value V0 as described above. If the voltage amplitude is smaller than the threshold value, the PWM current control is maintained (S303). If the amplitude is equal to or larger than the threshold, the control is switched to rectangular wave voltage control (S306).

On the other hand, if the current control is in the rectangular wave voltage control mode, it is next determined whether or not the absolute value | I | of the current vector detected by the current sensor 40 is less than a predetermined threshold value I0. I do. If the absolute value of the current vector is large and equal to or larger than the threshold value, the control is switched based on the current phase as in the related art (S305). That is, if the current phase is less than the predetermined value, the mode is switched to the PWM current control (S30).
3) If the current phase is equal to or greater than the predetermined value, the rectangular wave voltage control is maintained (S306). When the absolute value of the current vector is smaller than the predetermined value and the current sensor is susceptible to noise or current fluctuation, the control is switched based on the d-axis component Id of the current vector instead of the current phase. Specifically, it is determined whether or not Id exceeds a predetermined threshold value Id0. If it exceeds the threshold value, the mode is switched to the PWM control mode (S303). The rectangular wave voltage control is maintained (S306). Needless to say, the threshold value Id0 is determined from the rectangular wave voltage control region in FIG. 9, and for example, Id0 = 0 can be set.

In this embodiment, the current phase and Id
When detecting the current phase, it is preferable to calculate the current phases φi and Id by sampling at the switching timing and at an intermediate timing between the switching timings as in the above-described embodiment, and calculating the average value thereof.

As described above, when switching from the rectangular wave voltage control to the PWM current control, the control mode can be reliably switched by using the position of the current vector or the d-axis component of the current vector instead of the current phase. .

Next, when switching the control mode by the voltage amplitude, the current phase, or the current vector, the inverter 36
The processing in the case where these operations are stopped and these physical quantities cannot be detected will be described.

FIG. 11 is a block diagram showing another configuration of the driving device 10. In the present embodiment, it is assumed that the vehicle driver shifts the shift position from the D range to the N range during traveling in the EV or the HV, and then returns to the D range from the N range. When the shift position is in the N range, the ECU (not shown) detects the N range, shuts off the gate of the inverter 36, and stops driving the motor 38. At this time,
The voltage amplitude for switching from the PWM current control mode to the rectangular wave voltage control mode,
The current phase or current vector when switching to the M current control mode cannot be detected. Of course, if the vehicle is returned from the N range to the D range again, and if the running state of the vehicle does not change due to a short period of time in the N range, the control mode immediately before shifting to the N range may be used even after the return to the D range. There is no problem if you continue running,
While shifting to the N range, the running condition of the vehicle changes greatly,
It can be assumed that it is not preferable to keep the control mode as it is. For example, during the rectangular wave voltage control mode, the range was shifted from the D range to the N range, and when the range was returned from the N range to the D range again, where the PWM current control should be originally performed, the rectangular wave voltage control was continuously used. In this case, the voltage applied to the motor is too large and the current is disturbed. Conversely, if the PWM current control is performed where rectangular wave voltage control should be performed, the field weakening control cannot be performed and the current cannot be supplied as instructed. Problems can arise.

Therefore, in the present embodiment, even if the shift position changes from the D range to the N range and the gate of the inverter 36 is shut off, the motor 38 is switched to the PWM mode.
It is configured to accurately determine whether to perform current control or rectangular wave voltage control.

That is, in FIG. 11, a resolver 52 is provided in the motor 38, and the rotational position (angle) of the rotor is
Is detected and output to the rotation speed calculation unit 54. In the rotational speed calculating section 54, the motor 38 is operated based on the signal from the resolver 52.
Is calculated and supplied to the back electromotive voltage calculator 56. The back electromotive voltage calculation unit 56 calculates the back electromotive voltage of the motor 38 from the rotation speed calculated by the rotation speed calculation unit 54 based on the design parameters of the motor 38, and supplies the calculated back electromotive voltage to the voltage ratio determination unit 58. The voltage ratio determination unit 58 calculates the ratio between the back electromotive voltage of the motor 38 and the DC voltage of the battery 60 that drives the inverter 36, and compares and compares this ratio with a predetermined value to control switching of the switch 28. As the rotation speed of the motor 38 increases, the back electromotive force also increases, and in rectangular wave voltage control, the voltage amplitude is determined by the voltage of the battery 60. Therefore,
If the ratio of the back electromotive voltage to the voltage of the battery 60 at which the rotation speed of the motor 38 greatly fluctuates is equal to or more than a predetermined value, it can be determined that rectangular wave voltage control is performed. If the rotation speed of the motor 38 is small and the ratio is less than a predetermined value, PWM current control is performed. Can be determined. In this determination, the inverter 38 controls the motor 38
Note that no voltage amplitude, current phase, or current vector is used when driving.

FIG. 12 schematically shows how the voltage ratio determination section 58 makes a determination. In the figure, the horizontal axis represents the rotation speed of the motor 38, and the vertical axis represents the back electromotive voltage / battery voltage ratio. As the rotation speed increases, the back electromotive voltage / battery voltage ratio also increases. When the ratio exceeds a predetermined value (0.78 in the figure), the mode shifts to the rectangular wave voltage control mode. Performs PWM current control.

As described above, in the present embodiment, the rotation speed of the motor 38 is calculated, the back electromotive voltage of the motor 38 is calculated from the rotation speed, and the PWM current control and the rectangular wave voltage control are performed based on the back electromotive voltage. Therefore, even in a situation where the gate of the inverter 36 is shut off, specifically, in a situation where the shift position is in the N range, it is possible to correctly determine which control mode the motor 38 should be controlled in. Therefore, even when the shift position returns from the N range to the D range again, the motor 38 can be controlled in the correct control mode.

FIG. 13 shows a processing flowchart in this embodiment. First, it is determined whether the gate of the inverter 36 is in the cut-off state and the operation of the inverter 36 is stopped (S401). This determination may be made more directly by determining whether the shift position is in the N range. If the gate is not shut off, control is switched based on the voltage amplitude, current phase, or current vector as described above. Specifically, when the current control is the PWM current control (determined as the PWM current control in S402), the control is switched between the PWM current control and the rectangular wave voltage control according to the magnitude of the voltage amplitude (S4).
03, S404, S406). If the current control is rectangular wave voltage control, both control modes are switched according to the magnitude of the current phase (S404, S405, S40).
6). As described above, the current phase is preferably sampled at the switching timing and at an intermediate timing between the switching timings, and the average is preferably calculated. Current vector and I
The same applies to d.

On the other hand, in the gate cutoff state, the voltage amplitude or the current phase cannot be used.
As an alternative, the ratio E / Vb between the back electromotive voltage E and the battery Vb calculated by the back electromotive voltage calculator 56 is compared with a predetermined threshold value (S407). If the ratio E / Vb between the back electromotive voltage and the battery voltage is less than the predetermined value, the next control mode is set to the PWM current control mode (S40).
8) If it is not less than the predetermined threshold, the next control mode is set to the rectangular wave voltage control mode (S409). The control mode determined in S408 or S409 can be realized by switching the switch 28 while the inverter 36 is stopped.
When the switch 6 is in the stop state, the control mode is merely determined, and the switch 28 can be switched when the gate of the inverter 36 is again in the operating state.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications can be made. For example, in FIG.
The counter electromotive voltage E of the motor 38 is calculated from the rotation speed detected by the rotation speed calculation unit 2 and the rotation speed calculation unit 54. However, a voltage sensor is more directly provided on the motor 38, and the voltage sensor detects the back electromotive force of the motor 38. The voltage E may be detected and supplied to the voltage ratio determination unit 58.

FIG. 14 shows a configuration example in such a case. The motor 38 is provided with a voltage sensor 62. The voltage sensor 62 detects a back electromotive voltage of the motor 38 in a state where the gate of the inverter 36 is shut off, and supplies the voltage to the voltage ratio determination unit 58.

[0069]

As described above, according to the present invention, even if the current supplied to the motor in the rectangular wave voltage control mode contains a high-order component accompanying the phase switching, the torque value or the current phase can be accurately determined. Thus, the rectangular wave voltage control can be performed with high accuracy.

Further, according to the present invention, it is possible to appropriately switch between PWM current control and rectangular wave voltage control.

Further, according to the present invention, even when the operation of the inverter is stopped, the control state of the motor can be accurately determined, so that even when the inverter returns to the operation state, an appropriate control mode is maintained. The motor can be driven.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of a driving device according to an embodiment.

FIG. 2 is a timing chart showing a current sampling timing.

FIG. 3 is a detailed configuration block diagram of a torque detection unit.

FIG. 4 is a processing flowchart of the embodiment.

FIG. 5 is a detailed configuration block diagram of a torque detector according to another embodiment.

FIG. 6 is a configuration block diagram of a current phase detection unit according to the embodiment.

FIG. 7 is a processing flowchart in FIG. 6;

FIG. 8 is a configuration block diagram of a driving device according to another embodiment.

9 is an explanatory diagram of a control area map in FIG.

FIG. 10 is a processing flowchart in FIG. 8;

FIG. 11 is a configuration block diagram of a driving device according to another embodiment.

FIG. 12 is an explanatory diagram of a process of a voltage ratio determination unit in FIG. 11;

FIG. 13 is a processing flowchart in FIG. 11;

FIG. 14 is a configuration block diagram of a driving device according to still another embodiment.

[Explanation of symbols]

10 drive device, 12 current command generator, 14 current controller, 16 voltage amplitude determiner, 18 voltage phase controller,
20 Torque detector, 22 current phase determiner, 28 switch, 36 inverter, 38 motor, 40 current sensor.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroki Otani 41-cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture F-term in Toyota Central Research Laboratory Co., Ltd. QN04 QN09 QN22 QN23 RB21 RB22 TB10 TD20 TO04 TO12 TO13 TO14 5H576 AA15 BB06 CC02 DD02 DD07 EE01 EE11 EE19 EE30 GG01 GG04 GG05 HB02 JJ08 JJ17 JJ24 JJ26 LL12 LL22 LL24 LL25 LL28 LL28

Claims (10)

[Claims] 1. A PWM current control means for outputting a sine wave current having a predetermined amplitude and a predetermined phase in accordance with a torque command; a rectangular wave voltage control means for outputting a rectangular wave voltage in accordance with a torque command; Switching means for switching between the output of the means and the output of the rectangular wave voltage control means and supplying the output to the AC motor.A drive control device for an AC motor, wherein the rectangular wave voltage control means Means for detecting the current and the output voltage of the power supply at a predetermined timing, means for calculating the power at each timing based on the detected current and voltage, means for averaging the power at each calculated timing, and averaging Means for calculating an output torque of the AC motor based on the obtained electric power, and a drive control device for the AC motor. 2. A PWM current control means for outputting a sine wave current having a predetermined amplitude and a predetermined phase in accordance with a torque command, a rectangular wave voltage control means for outputting a rectangular wave voltage in accordance with a torque command, and the PWM current control. Switching means for switching between the output of the means and the output of the rectangular wave voltage control means and supplying the output to the AC motor; anda drive control device for the AC motor, comprising: A drive control device for an AC motor, comprising: means for detecting a phase at a predetermined timing; and means for averaging a detected current phase, wherein switching is performed according to the averaged current phase. 3. The drive of an AC motor according to claim 1, wherein the predetermined timing is a switching timing of the rectangular wave voltage and an intermediate timing between the switching timings. Control device. 4. The driving device for an AC motor according to claim 1, wherein the averaging unit includes a low-pass filter. 5. A PWM current control means for outputting a sine wave current having a predetermined amplitude and a predetermined phase in accordance with a torque command; a rectangular wave voltage control means for outputting a rectangular wave voltage in accordance with a torque command; Switching means for switching between the output of the means and the output of the rectangular wave voltage control means and supplying the output to the AC motor, and a drive control device for the AC motor, wherein the switching means comprises a current vector to the AC motor. And a region determining means for determining whether or not is located within a predetermined region, wherein the switching is performed based on the determination. 6. The apparatus according to claim 5, wherein said determining means includes: an absolute value determining means for determining whether a magnitude of the current vector is equal to or greater than a predetermined value. When the magnitude of the current vector is greater than or equal to a predetermined value, switching is performed based on the phase of the current vector, and when the magnitude of the current vector is less than a predetermined value, switching is performed based on the determination by the area determination unit. AC motor drive control device. 7. The apparatus according to claim 5, wherein the area determination unit makes the determination based on a d-axis component of the current vector in a dq plane. Drive control device. 8. A PWM current control means for outputting a sine wave current having a predetermined amplitude and a predetermined phase in accordance with a torque command; a rectangular wave voltage control means for outputting a rectangular wave voltage in accordance with a torque command; Switching means for switching between the output of the means and the output of the rectangular wave voltage control means and supplying the output to the AC motor.A drive control device for an AC motor, wherein the switching means comprises a back electromotive force of the AC motor. And a means for comparing the back electromotive voltage with an input voltage of an inverter that drives the AC motor, wherein the switching is performed based on the comparison. 9. The apparatus according to claim 8, wherein said means for detecting comprises: means for calculating a rotation speed based on a signal from a resolver provided in said AC motor; and said counter electromotive force based on said rotation speed. A drive control device for an AC motor, comprising: means for calculating a voltage. 10. The device according to claim 8, further comprising: a unit that detects a stop state of the inverter, wherein the switching unit switches when the inverter is in a stop state. A drive control device for an AC motor.