Engine control unit and electric vehicle

Abstract

The processor of the motor control device 300 performs normal control of the conversion of direct current supplied by a DC power supply into alternating current and the supply of the alternating current to the motor (PMSM 1) by switching a variety of switching elements of the inverter when the inverter (power converter 2) and the DC power supply (DC voltage source 9) are connected. When the inverter and the DC power supply are disconnected (detection of an electrical fault), the processor performs constant output voltage control to fix the inverter output voltage to a value close to zero by switching the variety of switching elements. As a result, when the DC power supply and the inverter are disconnected, the inverter capacitor overvoltage and the motor current oscillation are suppressed.

Description

Technical field

[0001] The present invention relates to a motor control device and an electric vehicle. Background technology

[0002] The motor drive system is equipped with an on / off switch that disconnects the DC power supply and the inverter to protect the DC power supply (battery in the case of an automobile) from overvoltage and overcurrent. When the on / off switch disconnects, the inverter's capacitor is charged by the motor's regenerative power, and there is a risk of the capacitor being damaged by overvoltage.

[0003] In patent literature 1, when the separation is carried out by the opening / closing unit, the upper arm or the lower arm of the inverter is all switched on to perform a three-phase short circuit, thereby suppressing the capacitor overvoltage.

[0004] In patent literature 2, the control of the current is carried out at the time of the three-phase short circuit, and then the three-phase short circuit is carried out to suppress the overvoltage of the capacitor and the current jump at the time of the three-phase short circuit switching. Citation list of patent literature PTL 1: JP H9-47055 A PTL 2: JP 6342043 B2 PTL 3: JP 5948266 B2 PTL 4: JP 2021-151003 A Summary of the invention: Technical problem

[0005] In the method described in patent literature 1, the overvoltage of the capacitor can be suppressed, but the current jump at the time of switching the three-phase short circuit becomes a problem.

[0006] In patent literature 2, although this corresponds to the fact that the output voltage in the three-phase short circuit is uniquely determined, a current step occurs depending on the current controlled immediately before the three-phase short circuit. Alternatively, the problem is that the current oscillation continues after switching to the three-phase short circuit.

[0007] In view of the present problem, one object of the present invention is to provide a motor control device and an electric vehicle that are able to suppress the overvoltage of a capacitor of an inverter and the current oscillation of a motor when the DC power supply and the inverter are separated from each other. Solution to the problem

[0008] To achieve the above objective, a motor control device according to an example of the present invention comprises a processor that performs normal control of the switching of a plurality of switching elements of an inverter to convert a direct current supplied by the DC power supply into an alternating current and to supply the alternating current to a motor in a state in which the inverter and the DC power supply are connected, and output voltage constant control of the switching of the plurality of switching elements to fix an output voltage of the inverter to a value close to zero in a case in which the inverter and the DC power supply are disconnected. Advantageous effects of the invention

[0009] According to the present invention, when the DC power supply and the inverter are separated, the overvoltage of the inverter's capacitor and the current oscillation of the motor can be suppressed. Problems, configurations, and effects not described above will be clarified by referring to the description of the embodiments below. Brief description of the drawings Fig. Figure 1 is a block diagram illustrating an overall configuration of an engine control device according to a first embodiment. Fig. Figure 2 is an example of a block diagram of a current command value generation unit in the first embodiment. Fig. Figure 3 is an example of a block diagram of an output voltage switching unit in the first embodiment. Fig. Figure 4 is a flowchart in the first embodiment. Fig. 5 is an example of a voltage command value in the first embodiment. Fig. Figure 6 is a block diagram illustrating an overall configuration of an engine control device in a second embodiment. Fig. Figure 7 is an example of a block diagram of a damping ratio control unit 14 in the second embodiment. Fig. Figure 8 is an example of a block diagram of an output voltage switching unit 18B in the second embodiment. Fig. 9A is an example of a voltage command value in the second embodiment. Fig. 9B is another example of the voltage command value in the second embodiment. Fig. Figure 10 is a block diagram illustrating an overall configuration of an engine control device according to a third embodiment. Fig. Figure 11 is an example of a block diagram of a damping ratio control unit 14B in the third embodiment. Fig. Figure 12 is a configuration diagram of an electric vehicle according to a fourth embodiment. Description of embodiments

[0010] In the following description, a permanent magnet synchronous motor (PMSM) is one target, but the effects of the embodiments of the present invention are not limited to PMSM, and similar effects can be achieved in the case of AC motors such as a synchronous reluctance motor, a permanent magnet synchronous generator, a winding-type synchronous machine, an induction motor and induction generator, and an AC generator. Although the semiconductor switching element of the inverter device is an IGBT, the effect of the embodiment of the present invention is not limited to this and can be a MOSFET or another power semiconductor element. [First embodiment]

[0011] The components of the first embodiment will now be described.

[0012] Fig. Figure 1 is a block diagram illustrating an overall configuration of an engine control device 300 according to the first embodiment of the present invention.

[0013] An overall configuration of the motor control device 300 of the present embodiment is described with reference to Fig. 1 described. In Fig. 1 comprises a power converter 2, an opening / closing unit 6 and a capacitor 8 between the power converter 2 and a DC voltage source 9 (for example, a battery), wherein the opening / closing unit 6 is closed during normal operation and a PMSM 1 is driven by converting DC current from the DC voltage source 9 into AC current according to a gate signal to be described later.

[0014] A phase current detection unit 3 comprises a Hall-effect current transformer (CT) or the like and detects current waveforms Iuc, Ivc, and Iwc of three phases—a U-phase, a V-phase, and a W-phase—flowing from the power converter 2 to the PMSM 1. A magnetic pole position detection unit 4 comprises a resolver or the like, detects the magnetic pole position of the PMSM 1, and outputs magnetic pole position information θ*. A frequency calculation unit 5 outputs velocity information ω1* from the magnetic pole position information θ* detected by the magnetic pole position detection unit 4, for example, by differential calculation.

[0015] A coordinate conversion unit 7 performs a coordinate conversion of Iuc, Ivc, and Iwc, detected by the phase current detection unit 3, using the magnetic pole position information θ*, detected by the magnetic pole position detection unit 4, and outputs dq-axis current detection values ​​Idc and Iqc. Under normal conditions, the current command value generation unit 12 generates dq-axis current command values ​​Id* and Iq* based on a torque command value T* and velocity information ω1*, using, for example, a lookup table or a formula. Operation when the open / close unit 6 is opened due to a power supply anomaly or similar event will be described later.

[0016] The current control unit 16 performs PI control such that the currents (dq axis current detection values ​​Idc, Iqc) match the respective dq (dq axis current command values ​​Id*, Iq*) and outputs dq axis voltage command values ​​Vdc*, Vqc*. The output voltage switching unit 18 normally outputs the dq axis voltage command values ​​Vdc*, Vqc*. Operation when the open / close unit 6 is opened due to a power supply anomaly or the like will be described later. The coordinate conversion unit 11 performs a coordinate conversion of the dq axis voltage command values ​​Vd*, Vq* based on the magnetic pole position θ* into three-phase voltage command values ​​Vu*, Vv*, Vw*. The PWM controller 10 generates a pulse in comparison to, for example, a triangle wave and generates and outputs a gate signal taking into account a dead time.

[0017] The current command value generation unit 12 and the output voltage switching unit 18, which are points of the embodiment of the present invention, are described below.

[0018] Fig. Figure 2 is an example of the current command value generation unit 12. A normal current command value generation unit 21 receives the torque command value T* and the velocity w1* as inputs and generates normal dq-axis current command values ​​Idn* and Iqn*, for example, in a lookup table. Next, in an opening dq-axis current command value generation unit 23, for example, opening dq-axis current command values ​​Idop* and Iqop* are set by formula 1 according to the steady-state current of the output voltage constant control at the time of opening. [Math. 1] Idop*=RVdcst*+ω1*Lq(Vqcst*−ω1*ϕm)R2+ω1*2LdLqIqop*=−ω1*LdVdcst*+R(Vqcst*−ω1*ϕm)R2+ω1*2LdLq}

[0019] Here, Vdcst* and Vqcst* represent dq-axis voltage command values ​​during constant output voltage control. Note that R is the motor resistance, Φm is the permanent magnet's linkage flux, Ld is the d-axis inductance, and Lq is the q-axis inductance.

[0020] With the configuration as in Formula 1, it is possible to switch between opening current control and constant output voltage control without torque surge or current fluctuation in a state where no parameter error exists. A switch 25 outputs the normal dq axis current command values ​​Idn* and Iqn* as the dq axis current command values ​​Id* and Iq* when an opening control flag fop is off, and outputs the opening dq axis current command values ​​Idop* and Iqop* when the opening control flag fop is on.

[0021] Fig. Figure 3 is an example of the output voltage switching unit 18. When the open control flag fop is turned on, a turn-on time delay 31 turns on an output voltage constant control flag fcst after a predetermined time has elapsed. The predetermined time is, for example, set to five times or more the current control time constant, and the flag is turned on in a state where the dq-axis current matches the open current command values ​​Idop* and Iqop*. A switch 37 outputs the dq-axis voltage command values ​​Vdc* and Vqc* as the dq-axis voltage command values ​​Vd* and Vq* when the output voltage constant control flag fcst is off, and outputs the open dq-axis voltage command values ​​Vdop* and Vqop* when the output voltage constant control flag fcst is on.

[0022] Switching-shift period change magnitude limits 33 and 35 provide change magnitude limits for the dq-axis voltage command values ​​Vdcst* and Vqcst* during constant output voltage control and output the opening dq-axis voltage command values ​​Vdop* and Vqop*. By providing the change magnitude limit, it is possible to suppress the occurrence of current oscillation due to a rapid change in the output voltage.

[0023] Fig. 4 illustrates flowcharts of the patent literature 2 and the embodiment of the present invention, and Fig. Figure 5 illustrates waveform examples of voltage command values ​​from patent literature 2 and the embodiment of the present invention (however, one example is illustrated in which both the dq-axis voltage command values ​​Vdcst* and Vqcst* are set to 0 V during output voltage constant control).

[0024] In patent literature 2, when a power supply anomaly (switch opening) is detected, the opening current control is performed. The current is controlled so that it is close to the stable current of the three-phase short circuit, and the current is switched to the three-phase short circuit after it converges. In the case of the three-phase short circuit, since the voltage is fixed at 0 V, a stage is generated due to a fault, such as a parameter error, at the time of switching.

[0025] On the other hand, in the embodiment of the present invention, when a power supply anomaly (switch opening) is detected, the opening control flag fop is turned on and the opening current control is activated. In the opening current control, the current command value of Formula 1, which differs from the normal time, is set, and the current is controlled so that it is close to the stable current of the output voltage constant control.

[0026] Subsequently, when the constant output voltage control flag fcst is turned on after a predetermined time in the turn-on delay 31 has elapsed, the output voltage is switched from the current-control dq axis voltage command values ​​Vdc* and Vqc* to the open dq axis voltage command values ​​Vd* and Vqop*. However, the output voltage is switched smoothly until it is controlled to a constant state by the switching-off-period-change-magnitude limits 33 and 35. Unlike the three-phase short circuit, because the output voltage can be switched, smooth switching can be performed, and the current jump at the time of switching can be suppressed.

[0027] If both the dq-axis voltage command values ​​Vdcst* and Vqcst* are set to 0 V during constant output voltage control, the dq-axis voltage command values ​​Vdcst* and Vqcst* are equivalent to a three-phase short circuit, but are not necessarily set to 0 V. The voltage can be approximately 0 V, which is a voltage that allows for an increase in capacitor voltage.

[0028] Additionally, in the embodiment of the present invention, since there is a possibility that the capacitor voltage increases depending on the dead-time compensation error, it is preferable to set the d-axis voltage command value Vdcst* to a tiny negative value during constant output voltage control in order to suppress the increase in capacitor voltage. In particular, if the maximum dead-time compensation error dt er The maximum error can be set using the following formula 2. [Math. 2] Vdcst*=−dter×fc×Vdc

[0029] Here, fc represents a carrier frequency, and Vdc represents a DC voltage. When the output voltage is set to approximately 0, the current flows in the negative direction of the d-axis. In this case, the voltage error ΔVdt* due to the dead time appears entirely in the d-axis voltage and is expressed by the following formula 3. [Math. 3] ΔVdt*=dt×fc×Vdc

[0030] Dead-time compensation is implemented to compensate for this, but if the compensation is insufficient, the capacitor voltage increases due to the input power, which is calculated as the product of the voltage error ΔVdt* and the d-axis current Idc. To prevent this, the d-axis voltage command value Vdcst* can be adjusted. Instead of setting the d-axis voltage command value Vdcst* to a negative value, the same effect can be achieved by setting the dead-time compensation adjustment amount to overcompensate for an expected error.

[0031] The q-axis voltage command value Vqcst* is preferably set to 0 V as an average value to suppress fluctuations in the capacitor voltage.

[0032] In the present embodiment, when the opening of the switch is detected, the opening control flag fop is turned on. However, as a method for detecting the opening of the switch, there may be, for example, any case in which the capacitor voltage remains below a predetermined value for a predetermined time or a signal is received from the switch. In a system without a switch, for example, there may be a case in which the opening of the switch is determined because the wiring at the switch section is disconnected and the capacitor voltage becomes low.

[0033] In the three-phase short circuit, heat is concentrated on either the upper arm or the lower arm, whereas in the present embodiment, heat can be distributed to both the upper and lower arms. Furthermore, the coordinate conversion unit 11 can establish the thermal equilibrium between the upper and lower arms by adjusting the zero-phase voltages during coordinate conversion of the dq-axis voltage command values ​​Vd* and Vq* to the three-phase voltage command values ​​Vu*, Vv*, and Vw* based on the magnetic pole position θ*.

[0034] In the present embodiment, the switching control is performed after the opening current control has been performed, but the switching control can be performed directly without performing the opening current control.

[0035] In the present embodiment, the opening dq axis current command values ​​Idop* and Iqop* are set. However, the dq axis current command values ​​Idop* and Iqop* can be set as in Formula 4, ignoring the resistance. [Math. 4] Idop*=Lq(Vqcst*−ω1*ϕm)ω1*LdLqIqop*=−LdVdcst*ω1*LdLq}

[0036] Alternatively, the dq-axis voltage command values ​​Vdcst* and Vqcst* can be approximated to 0 during constant output voltage control, taking into account that they are infinitesimally set, and can be set as in Formula 5. [Math. 5] Idop*=ϕmLdIqop*=0}

[0037] In the embodiment of the present invention, since the switching can be carried out smoothly, it is possible to switch to constant output voltage control without the current jumping, even if a slight fault is present.

[0038] The main features of the first embodiment can also be summarized as follows.

[0039] The processor of the motor control device 300 performs normal control of the conversion of direct current supplied by a DC power supply into alternating current and the supply of the alternating current to the motor (PMSM 1) by switching a variety of switching elements of the inverter when the inverter (power converter 2) and the DC power supply (DC voltage source 9) are connected. When the inverter and the DC power supply are disconnected (detection of an electrical fault), the processor performs constant output voltage control to maintain the output voltage of the inverter by switching the variety of switching elements ( Fig. 5) to fix it to a value close to zero.

[0040] Since the output voltage of the inverter (power converter 2) is fixed at a value close to zero by switching the numerous switching elements, the output voltage can be switched smoothly. As a result, the current surge at the time of switching to constant output voltage control is suppressed. Consequently, when the DC power supply and the inverter are disconnected, the overvoltage of the inverter's capacitor and the current oscillation of the motor can be suppressed. Additionally, heat can be dissipated between the upper and lower arms of the inverter.

[0041] The value close to zero (including zero) is determined by a mathematical formula, experiment, simulation, or the like, so that the capacitor does not cause an overvoltage when the inverter and DC power supply are disconnected.

[0042] For example, in constant output voltage control, the processor fixes the q-axis output voltage (the q-axis voltage instruction value Vqcst*) to zero. As a result, an increase in the inverter's (power converter 2) capacitor voltage is suppressed. Consequently, a smaller capacitor and a reduction in cost can be achieved.

[0043] In constant output voltage control, the processor preferably sets a fixed value (the d-axis voltage instruction value Vdcst*), which is the midpoint of the d-axis output voltage, to a minuscule negative value. As a result, the induced voltage is suppressed. Consequently, the increase in the inverter's capacitor voltage is further suppressed.

[0044] In constant output voltage control, the processor changes the fixed value (the d-axis voltage instruction value Vdcst*) proportionally to one or both of the carrier frequency fc and the DC voltage Vdc (Formula 2). As a result, an increase in capacitor voltage due to insufficient dead-time compensation is suppressed.

[0045] The processor can set a fixed value (the d-axis voltage instruction value Vdcst*), which is a midpoint of the d-axis output voltage, to zero in the output voltage constant control. As a result, an increase in the inverter's capacitor voltage is suppressed.

[0046] When the inverter and DC power supply are disconnected (electrical fault detection), the processor performs an opening current control to switch the multiple switching elements so that the motor current (PMSM 1) becomes a steady current (opening dq axis current command values ​​Idop*, Iqop*, Formula 1) in the constant output voltage control. As a result, torque surge and current oscillation at the time of switching from opening current control to constant output voltage control can be suppressed.

[0047] When the inverter and the DC power supply are disconnected (detection of an electrical deficiency), the processor performs a displacement control to gently adjust the inverter's output voltage to a value close to zero (change magnitude limits 33 and 35). Fig. 3) As a result, the current oscillation can be further suppressed. In the displacement control, in addition to the change magnitude limits 33 and 34 of the first embodiment, a low-pass filter can be used to smoothly adjust the output voltage to a value close to 0. (Second embodiment)

[0048] Now the components of the second embodiment will be described.

[0049] Fig. Figure 6 is a block diagram illustrating an overall configuration of an engine control device 300 according to the second embodiment of the present invention.

[0050] A difference in configuration from the first embodiment is described.

[0051] In the second embodiment, a damping ratio control unit 14 is added and an output voltage switching unit 18 is changed to an output voltage switching unit 18B.

[0052] The damping ratio control unit 14 is, for example, as in Fig. Figure 7 illustrates the configuration. The q-axis current command value is passed through a first-order delay filter 41, taking into account a delay of ωc, which is a cutoff frequency, and then through the current control unit 16. A difference is obtained from the q-axis current detection value Iqc, and a first-order fundamental oscillation component is extracted by a high-pass filter 45. Furthermore, a multiplier 47 multiplies the velocity ω1*, a gain 49 multiplies the damping ratio ζ twice by the q-axis inductance Lq, and a q-axis damping ratio control voltage command value Vqd* is output. Furthermore, the q-axis damping ratio control voltage command value Vqd* and the q-axis current detection value Iqc are multiplied by a multiplier 51, Idc is divided by a divider 53 and -1 is multiplied by a gain 55 to output a d-axis damping ratio control voltage command value Vdd*.

[0053] The output voltage switching unit 18B is, for example, as in Fig. 8 illustrates the configuration. The difference of Fig. 3 consists in eliminating the change amount limits 33 and 35 and adding an adder 38 and an adder 39. In the present embodiment, since the current oscillation can be suppressed at the time of switching by the damping ratio control unit 14, the oscillation can be suppressed without providing the switching period.

[0054] The principle is described below.

[0055] The damping ratio control is a controller that suppresses a first-order fundamental wave oscillation component and is proposed, for example, in patent literature 3. At the time of the three-phase short circuit, the current oscillation converges to a stable value while oscillating with the first-order fundamental wave oscillation component. Since the voltage can be controlled by the constant output voltage control, unlike the three-phase short circuit as in the embodiment of the present invention, the oscillation can be suppressed at the time of switching by suppressing the first-order fundamental wave oscillation component.

[0056] The reason damping ratio control is performed on the q-axis is that the current command value on the q-axis side is essentially zero. The input power is proportional to the product of the voltage and current, and a large current flows in the negative direction on the d-axis side. Here, when damping ratio control is performed in the d-axis direction, the capacitor voltage fluctuates greatly due to the oscillation of the voltage command value. On the other hand, since the current command value on the q-axis side is essentially zero, the current is only the oscillation component, and the magnitude of the fluctuation is small. Furthermore, if the d-axis damping ratio control voltage command value Vdd* is given by the following formula 6 to cancel the input power Pqd on the q-axis side, the fluctuation of the capacitor voltage due to damping ratio control can be completely suppressed. [Math. 6] Vdd*=−PqdIdc=−Vqd*IqcIdc

[0057] In the present embodiment, as in the first embodiment, the d-axis voltage command value Vdcst* is preferably set to a tiny negative value during the output voltage constant control.

[0058] As described above, according to the present embodiment, both the capacitor overvoltage and the current oscillation can be suppressed.

[0059] The main features of the second embodiment can also be summarized as follows.

[0060] As in Fig. As illustrated in Figure 9A, when the inverter (power converter 2) and the DC power supply (DC source 9) are disconnected, the processor performs damping ratio control to output a q-axis damping ratio control voltage (q-axis damping ratio control voltage command value Vqd*) to cancel any oscillatory component of the q-axis current or magnetic flux. In constant output control, the processor fixes the d-axis output voltage (the open d-axis voltage command value Vdop*) to a predetermined value (the d-axis voltage command value Vdcst*) and outputs a q-axis damping ratio control voltage (the q-axis damping ratio control voltage command value Vqd*), which is an output of the damping ratio control, as the q-axis output voltage (the open q-axis voltage command value Vqop*).

[0061] Consequently, it is possible to suppress the current oscillation at the time of switching to constant output voltage control without providing the switching period. As in Fig. As illustrated in Figure 8, the opening dq axis voltage command values ​​Vdop* and Vqop* are the sum of the dq axis voltage command values ​​Vdcst* and Vqcst* and the dq axis damping ratio control voltage command values ​​Vdd* and Vqd* during constant output voltage control. The example of Fig. 9A corresponds to a case in which the d-axis damping ratio control voltage command value Vdd* = 0 and the q-axis voltage command value Vqcst* = 0.

[0062] As in Fig. As illustrated in Figure 9B, in damping ratio control, the processor outputs the d-axis damping ratio control voltage (the d-axis damping ratio control voltage command value Vdd*) to cancel the power of the q-axis damping ratio control voltage (the q-axis damping ratio control voltage command value Vqd*). In constant output voltage control, the processor calculates the d-axis output voltage (the opening d-axis voltage command value Vdop*) by adding the d-axis damping ratio control voltage to a predetermined value (for example, a tiny negative value). This makes it possible to completely suppress the capacitor voltage fluctuation due to damping ratio control. The example of Fig. 9B corresponds to a case in which the q-axis voltage command value Vqcst* = 0. (Third embodiment)

[0063] The components of a third embodiment are described.

[0064] Fig. Figure 10 is a block diagram illustrating an overall configuration of an engine control device 300B according to the third embodiment of the present invention.

[0065] A difference in configuration from the second embodiment is described.

[0066] In the third embodiment, instead of the current control unit 16, the current is controlled using a magnetic flux command value generation unit 13, a magnetic flux estimation value generation unit 15, and a magnetic flux control unit 17, which are described in patent literature 4. Additionally, while the control is performed by the magnetic flux, the damping ratio control unit 14 is changed to a damping ratio control unit 14B.

[0067] The magnetic flux command value generation unit 13 generates dq-axis magnetic flux command values ​​φd* and φq* from the dq-axis current command values ​​Id* and Iq*. This is implemented using a lookup table, an approximation expression, or the like. The magnetic flux estimation value generation unit 15 generates dq-axis magnetic flux estimations φdc and φqc from the dq-axis current detection values ​​Idc and Iqc. The calculation method is similar to that of the magnetic flux command value generation unit 13. The magnetic flux control unit 17 performs control using a PI controller such that the dq-axis magnetic flux command values ​​φd* and φq* match the dq-axis magnetic flux estimations φdc and φqc. As described in patent reference 4, an inverse model of an integrator and a motor can be used.

[0068] The configuration of the damping ratio control unit 14B is in Fig. Figure 11 illustrates this. The q-axis magnetic flux command value is passed through a first-order delay filter 61, taking into account a delay of ωc, which is a cutoff frequency, and then through the magnetic flux control unit 17 to take a difference from the q-axis magnetic flux estimate φqc. A first-order fundamental oscillation component is extracted by a high-pass filter 65. Furthermore, the oscillation component is multiplied by a multiplier 67 with velocity ω1* and by twice the damping ratio ζ with a gain 69 to output the q-axis damping ratio control voltage command value Vqd*. Furthermore, the q-axis damping ratio control voltage command value Vqd* and the q-axis current detection value Iqc are multiplied by a multiplier 71, divided by Idc with a divider 73 and multiplied by -1 with a gain 75 to output the d-axis damping ratio control voltage command value Vdd*.

[0069] Even if the input to the damping ratio control is the magnetic flux, the current oscillation at the time of switching to the constant output voltage control can be suppressed as in the second embodiment. (Fourth embodiment)

[0070] The components of a fourth embodiment are described.

[0071] Fig.Figure 12 illustrates a configuration of an electric vehicle according to the fourth embodiment of the present invention. As illustrated in the first to third embodiments, the motor control device 300 (or 300B) controls the power supplied to the PMSM 1 by the power converter 2. The DC voltage source 9 (for example, a battery) supplies power to the power converter 2. The PMSM 1 is connected to a transmission 301. The transmission 301 is connected to a drive shaft 305 via a differential 303 and supplies power to the wheels 307. It should be noted that a configuration in which the transmission 301 is not provided and the PMSM 1 and the power converter 2 are directly connected to the differential 303, or a configuration in which the PMSM 1 and the power converter 2 are mounted on the front wheel and the rear wheel, respectively, can be used.

[0072] In the case of an automobile, torque fluctuations directly affect driving comfort. Therefore, the requirement for torque fluctuations is more stringent than in other applications, and the effect of the embodiment of the present invention is easily demonstrated. By applying the present invention, driving comfort can be improved at the time of an electrical power supply anomaly in an automobile.

[0073] The main features of the fourth embodiment can also be summarized as follows.

[0074] The electric vehicle includes the motor control device 300 (or 300B) according to one of the first to third embodiments. The motor (PMSM 1) delivers power to the wheels 307 of the electric vehicle. According to the motor control device 300 (or 300B), torque fluctuations during an electrical failure (when the battery and inverter are disconnected in the event of an inverter anomaly, such as overcurrent or overvoltage, battery anomaly, vehicle failure, collision, or the like) are suppressed. As a result, it is possible to suppress sudden changes in the driver's comfort during an electrical failure.

[0075] It should be noted that the present invention is not limited to the embodiments described above and includes various modifications. For example, the embodiments described above have been described in detail to explain the present invention in an easily understandable way and are not necessarily limited to those that have all the described configurations. In addition, part of the configuration of a particular embodiment can be replaced by the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a particular embodiment. Furthermore, it is possible to add, delete, and replace other configurations for part of the configuration of each embodiment.

[0076] Additionally, some or all of the configurations, functions, and the like described above can be implemented in hardware, for example, by designing them with an integrated circuit. Furthermore, the configurations, functions, and the like described above can be implemented in software, with the processor interpreting and executing a program that implements each function. Information such as a program, a table, and a file for implementing each function can be stored in a recording device such as memory, a hard disk drive, or a solid-state drive (SSD), or on a recording medium such as an IC card, an SD card, or a DVD.

[0077] The present embodiment may have the following aspects. (1) Inverter control device controlling an inverter circuit which converts a DC power supply into an AC power supply by switching a plurality of switching elements and supplies the AC power to a motor, wherein the inverter control device performs an output voltage constant control of fixing an output voltage of the inverter circuit to a value close to zero by switching the switching elements when an inverter and the DC power supply are disconnected due to the detection of an anomaly on a power supply side or the like. (2) AC motor control device according to (1) wherein the output voltage constant control fixes a q-axis output voltage to zero. (3) AC motor control device according to (1) wherein a damping ratio control for outputting a q-axis damping ratio control voltage to cancel an oscillation component of a q-axis current, and the output voltage constant control to fix a d-axis output voltage to a predetermined value and the q-axis output voltage is a q-axis damping ratio control voltage which is an output of the damping ratio control. (4) AC motor control device according to (3) wherein the damping ratio control unit outputs a d-axis damping ratio control voltage to cancel the power through the q-axis damping ratio control voltage and the output voltage constant control calculates the d-axis output voltage by adding the d-axis damping ratio control voltage to a predetermined value. (5) AC motor control device according to any of (2) to (4) wherein in the output voltage constant control a fixed value which is a midpoint of the d-axis output voltage is a negative tiny value. (6) AC motor control device according to (5) wherein in the constant output voltage control a midpoint of the d-axis output voltage is changed proportionally to one or both of a carrier frequency and a DC voltage. (7) AC motor control device according to any of (2) to (4) wherein in the output voltage constant control a fixed value which is a midpoint of the d-axis output voltage is zero. (8) AC motor control device according to any of (1) to (7), which further comprises an opening current control for switching the switching element, so that the current of the motor becomes a steady current in the output voltage constant control. (9) AC motor control device according to (8), which further comprises a switching control for smooth switching from the opening current control to the output voltage constant control. (10) Electric vehicle equipped with an AC motor control device driving an AC motor, the vehicle comprising the AC motor control device according to any one of (1) to (9) as a control device for the AC motor.

[0078] According to (1) to (10) both the capacitor overvoltage and the motor current oscillation can be suppressed, and both a reduction in capacitor capacitance and an improvement in driving comfort at the time of a power supply anomaly can be achieved. Reference symbol list 1 PMSM 2 power converters 3 Phase current detection unit (phase current detector) 4 Magnetic pole position detection unit (magnetic pole position detector) 5 Frequency calculation unit 6 Switching unit (switch) 7 Coordinate conversion unit 8 Capacitor 9 DC voltage source 11 Coordinate conversion unit 12 Current command value generation unit 13 Magnetic flux command value generation unit 14 Damping ratio control unit 14B Damping ratio control unit (third embodiment) 15 Magnetic flux estimation unit 16 Power control unit 17 Magnetic flux control unit 18 Output voltage switching unit 18B Output voltage switching unit (second embodiment) 21 Normal current command value generation unit 23 Opening dq axis current command value generation unit 25 switches (switches) 31 Switch-on time delay 33 Switching shift period change amount limit 35 Switching shift period change amount limit 37 switches (switches) 38 Adders 39 Adders 41 First-order delay filters (LPF) 43 subtractors 45 high-pass filters 47 Multipliers 49 reinforcements 51 Multipliers 53 pieces 55 amplification 61 First-order delay filters (LPF) 63 subtractors 65 High-pass filters 67 Multipliers 69 reinforcements 71 Multipliers 73 parts 75 Reinforcement 300 Engine control unit 300B Motor control unit 301 gearbox 303 Differential gear 305 Drive shaft 307 wheel QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP H9-47055 A

[0004] JP 6342043 B2

[0004] JP 5948266 B2

[0004] JP 2021-151003 A

[0004]

Claims

[1] Engine control device comprising a processor that executes: a normal control system for switching a large number of switching elements of an inverter in a state in which the inverter and are connected to a DC power supply to convert the direct current supplied by the DC power supply into an alternating current and to supply the alternating current to a motor; and A constant output voltage control for fixing the inverter's output voltage to a value close to zero by switching a multitude of switching elements when the inverter and the DC power supply are disconnected. [2] Motor control device according to claim 1, wherein the processor fixes a q-axis output voltage to zero in the constant output voltage control. [3] Motor control device according to claim 1, wherein the processor: a damping ratio control to output a q-axis damping ratio control voltage to cancel an oscillatory component of a q-axis current or magnetic flux when the inverter and DC supply are disconnected; and In the constant output voltage control, a d-axis output voltage is fixed to a predetermined value and a q-axis damping ratio control voltage is output as a q-axis output voltage, which is an output of the damping ratio control. [4] Motor control device according to claim 3, wherein the processor: in the damping ratio control, a d-axis damping ratio control voltage is output to cancel the power through the q-axis damping ratio control voltage, and In constant output voltage control, the d-axis output voltage is calculated by adding the d-axis damping ratio control voltage to the predetermined value. [5] Motor control device according to claim 2, wherein the processor in the output voltage constant control sets a fixed value, which is a midpoint of a d-axis output voltage, to a negative minuscule value. [6] Motor control device according to claim 5, wherein the processor in the constant output voltage control changes the fixed value proportionally to one or both of a carrier frequency and a DC voltage. [7] Motor control device according to claim 2, wherein the processor in the constant output voltage control sets a fixed value, which is a midpoint of the d-axis output voltage, to zero. [8] Motor control device according to claim 1, wherein the processor performs an opening current control of the switching of the plurality of switching elements, such that a current of the motor becomes a steady current in the output voltage constant control when the inverter and the DC supply are disconnected. [9] Motor control device according to claim 8, wherein the processor is further configured such that: when the inverter and the DC power supply are separate, A transition control is performed to gently adjust the inverter's output voltage to a value close to zero. [10] Electric vehicle comprising the motor control device according to claim 1, wherein the motor delivers power to wheels of the electric vehicle.

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