POWER CONVERSION DEVICE AND DRIVE DEVICE

Abstract

A power conversion device includes: a power conversion circuit that converts a direct current into an alternating current through PWM control and outputs three-phase alternating currents to a motor; a three-phase / two-phase conversion unit that converts the three-phase alternating currents into dq-axis currents; a DC voltage detection unit that detects a DC voltage value of the alternating current; and a first calculation unit that calculates dq-axis voltages based on motor parameters of the motor and the dq-axis currents, and calculates a first DC value of the direct current based on the dq-axis voltages, the dq-axis currents, and the DC voltage value.

Description

Technical area

[0001] The present invention relates to a power conversion device and a drive device. Technical background

[0002] In a vehicle that uses a motor for propulsion, such as a hybrid vehicle or electric vehicle, the motor or the like is driven by converting direct current supplied from a direct current power supply into alternating current using an in-vehicle power conversion device. To monitor the condition of the direct current power supply and diagnose the interior of the power conversion device, a technique for calculating a direct current supplied from the direct current power supply to the power conversion device is known.

[0003] For example, PTL 1 discloses a technique in which an alternating current is calculated using dq-axis voltage commands and dq-axis current commands, and a direct current is calculated based on the alternating current. Additionally, PTL 2 discloses a technique in which a direct current is calculated using an alternating current value and a duty cycle. Citation listPatent literature PTL 1: JP 2006-33970 A PTL 2: JP 2017-208893 A Summary of the inventionTechnical problem

[0004] However, if a fault occurs in the power conversion device and a voltage cannot be output according to the set value, the set value will deviate from the actual output voltage. Therefore, a method for calculating a DC current using a value corresponding to a set value such as a voltage set value or a duty cycle, as in the techniques described in PTL 1 and PTL 2, encounters a problem in that a correct DC current value cannot be calculated. Solution to the problem

[0005] A power conversion device according to one aspect of the present invention includes: a power conversion circuit that converts a direct current into an alternating current through PWM control and outputs three-phase alternating currents to a motor, a three-phase / two-phase conversion unit that converts the three-phase alternating currents into dq-axis currents, a DC voltage detection unit that detects a DC voltage value of the alternating current, and a first calculation unit that calculates dq-axis voltages based on motor parameters of the motor and the dq-axis currents, and calculates a first DC value of the direct current based on the dq-axis voltages, the dq-axis currents, and the DC voltage value.

[0006] A drive device according to one aspect of the present invention includes a motor and the above-described power conversion device that converts a direct current into an alternating current by PWM control and supplies three-phase alternating currents to the motor. Advantageous effects of the invention

[0007] According to the present invention, a correct DC current value can be calculated even in a state where a fault has occurred in the power conversion circuit. Brief description of the drawings

[0008] They show: Fig. 1 a schematic diagram of a vehicle, Fig. 2 is a diagram showing a schematic configuration of a drive device, Fig. 3 is a diagram showing an example of a configuration of a power conversion circuit, Fig. 4 is a control block diagram showing functions of a control circuit in detail, Fig. 5 is a diagram for explaining a second embodiment of the present invention, Fig. 6 is a diagram showing a correspondence between an operating state and a DC calculation value to be selected, Fig. 7 is a diagram showing an example of operation of a dialing unit, Fig. 8 is a diagram showing an example of a case where a switching operation is carried out in several stages, Fig. 9 is a diagram for explaining a third embodiment of the present invention and Fig. 10 is a diagram for explaining an operation of a selection unit according to the third embodiment. Description of embodiments

[0009] Embodiments for implementing the present invention will be described below with reference to the drawings. The following description and drawings are intended to describe the present invention by way of example, and some omissions and simplifications are appropriately made for the sake of clarity of explanation. In the following description, the same or similar elements and processes are denoted by the same reference numerals, and redundant description can be omitted. Note that only examples of embodiments of the present invention will be described below, and the present invention is not limited to the following embodiments and may be implemented in various other forms. (First embodiment)

[0010] A first embodiment of the present invention will be described with reference to the Fig. 1 to 4 described. Fig. Figure 1 is a schematic diagram of a vehicle driven by an engine (not shown). The vehicle 1 includes a drive device 2 to which electric power is supplied from a DC power supply 5. Although not shown, the drive device 2 includes a power conversion device, a motor, and a speed reducer. The drive power of the motor is transmitted via the speed reducer to an axle 4, on which wheels 3a are provided.

[0011] When in Fig. In the example shown in Figure 1, the drive device 2 is installed on the axle 4 for the front wheels (wheels 3a), but it may also be installed on the axle for the rear wheels (wheels 3b). Additionally, the drive devices 2 may be installed on the respective axles 4 for the front and rear wheels, or independent drive devices 2 may be installed on the left and right wheels 3a and 3b, respectively, instead of on the axles. In addition to the Fig. 1, a drive device using an internal combustion engine may be installed parallel to the drive device 2 on the axle 4.

[0012] Fig. 2 is a diagram showing a schematic configuration of the drive device 2. A DC power supply 5, a control device 6, and a failure notification device 7 are provided around the drive device 2. The control device 6 transmits a target torque τs, operation mode information Sm, etc. to the drive device 2. In addition, the control device 6 receives an output torque calculation value τ and a DC current calculation value Idc output from the drive device 2. Although only one control device 6 is described in the present embodiment, multiple control devices may transmit and receive information. The control device 6 also has a function of controlling the drive device using the internal combustion engine described above.

[0013] The DC power supply 5 is a power supply for driving a motor 9 in the drive device 2 and corresponds, for example, to a battery. The fault notification device 7 receives a fault detection signal Sf from the drive device 2 and notifies a passenger of the occurrence of a fault. As examples of fault notification, a lamp may be turned on, a warning sound may be generated, or a voice notification may be provided.

[0014] The drive device 2 includes a power converter 8, a motor 9, and a speed reducer (not shown). The speed reducer amplifies the driving force of the motor 9 and transmits the amplified driving force to the axle 4 (or the wheels 3a or 3b). The motor 9 is a three-phase motor with three windings inside, and it corresponds, for example, to a synchronous motor using a permanent magnet or an induction motor that does not use a permanent magnet.

[0015] The motor 9 has a motor angle sensor 91 and a motor temperature sensor 92. The motor angle sensor 91 measures the rotation angle of a rotor of the motor and outputs the measured angle as a motor angle sensor value θm to the power conversion device 8. The motor temperature sensor 92 measures the temperature of the motor 9 and outputs the measured temperature as a motor temperature sensor value Tm to the power conversion device 8.

[0016] The power conversion device 8 converts the direct current supplied from the direct current power supply 5 into alternating current based on the target torque or the like input from the control device 6 and supplies the alternating current to the motor 9. The power conversion device 8 also has a function of converting the current from the motor 9 into direct current to charge the direct current power supply 5.

[0017] The power conversion device 8 includes a control circuit 80, a driver circuit 81, a power conversion circuit 82, a DC voltage sensor 83, and an AC current sensor 84. The control circuit 80 generates a pulse width modulation (PWM) signal pwm for controlling the U-, V-, and W-phase current output from the power conversion device 8 to a predetermined value based on the target torque τs and the operation mode information Sm from the control device 6. Note that the control circuit 80 will be described in detail later. The driver circuit 81 outputs a driver signal for turning on / off a plurality of power semiconductors provided in the power conversion circuit 30 based on the PWM signal pwm output from the control circuit 80.

[0018] The DC voltage sensor 83 measures the output voltage of the DC power supply 5 and outputs the measured voltage value as the DC voltage sensor value Vdc to the control circuit 80. The AC current sensor 84 measures the AC current flowing through each of the phases (U-phase, V-phase, and W-phase) of the motor 9. The AC current values ​​measured by the AC current sensor 84 in the respective phases are output to the control circuit 80 as the AC current sensor values ​​Iu, Iv, and Iw. Fig. In the example shown in Figure 2, the AC current sensor 84 includes one sensor for each phase, but it may also be provided for only two phases. Because the relationship "U-phase current + V-phase current + W-phase current = 0" holds, the control circuit 80 calculates an AC current sensor value for the remaining phase in a configuration where sensors are provided for two phases.

[0019] The power conversion circuit 82 receives the drive signal from the drive circuit 81 to drive the power semiconductors provided therein and to control the current flowing through the motor 9. Fig. Figure 3 is a diagram showing an example of a configuration of the power conversion circuit 82. The power conversion circuit 82 includes a smoothing capacitor 821 and six power semiconductors 822. Two power semiconductors 822 forming upper and lower arms are provided for each of the phases (U-phase, V-phase, and W-phase). The output terminals of the upper and lower arms for each phase are connected to the windings for the corresponding phase of the motor 9.

[0020] The power semiconductor 822 is switched on / off according to the drive signal input from the driver circuit 81 and performs a conversion between direct current and alternating current. The power semiconductor 822 corresponds, for example, to a power metal-oxide-semiconductor field-effect transistor (MOSFET), an insulated-gate bipolar transistor (IGBT), or the like. Fig. In the example shown in Figure 3, an IGBT is used as the power semiconductor 822.

[0021] The smoothing capacitor 821 is a capacitor for smoothing a current generated by turning the power semiconductor 822 on / off and suppressing ripple in the DC current supplied to the power conversion circuit 82 from the DC power supply 5. For example, an electrolytic capacitor or a film capacitor is used as the smoothing capacitor 821.

[0022] According to the present embodiment, the neutral point of the motor is in a floating state, but it may also be connected to the ground (not shown). Methods for connecting the neutral point of the motor to the ground include a direct grounding method, a resistance grounding method, a compensation reactance grounding method, and an arc-extinguishing reactance grounding method.

[0023] Fig. 4 is a control block diagram detailing the functions of control circuit 80. Control circuit 80 includes a central processing unit (CPU), a random access memory (RAM), a read-only memory (ROM), a communication circuit, and the like (not shown). The CPU develops a program stored in ROM and transfers it to RAM and executes it, thereby implementing a function of each unit described later. The ROM may be an electrically erasable programmable ROM (EEPROM) or an electrically rewritable flash ROM.

[0024] The control circuit 80 includes a state control unit 801, a target current calculation unit 802, a current control unit 803, a PWM signal generation unit 804, a three-phase / two-phase conversion unit 805, a motor speed calculation unit 806, a DC current calculation unit 807, an output torque calculation unit 808, and a diagnostic unit 809.

[0025] The motor speed calculation unit 806 calculates a motor angular speed ω0 based on a change in the motor angle sensor value θm. The calculated motor angular speed ω0 is input to the target current calculation unit 802, the DC current calculation unit 807, and the output torque calculation unit 808.

[0026] Based on the motor angle sensor value θm, the three-phase / two-phase conversion unit 805 performs dq conversion, as shown in the following equation (1), in the three phases on the AC sensor values ​​Iu, Iv, and Iw, and calculates a d-axis current value Id and a q-axis current value Iq. The calculated d-axis current value Id and the calculated q-axis current value Iq are output to the current control unit 803 and the DC current calculation unit 807. [Mathematical Formula 1] [IdIq]=23[cos(θ)cos(θ−23π)cos(θ+23π)−sin(θ)−sin(θ−23π)−sin(θ+23π)][IuIvIw]

[0027] In equation (1), Iu, Iv, and Iw are AC sensor values ​​in the U-phase, V-phase, and W-phase, respectively measured by the AC sensor 84. θ is an electrical angle of the motor 9. The electrical angle θ can be calculated by multiplying the motor angle sensor value θm measured by the motor angle sensor 91 by the number of pole pairs of the motor 9. In equation (1), the dq conversion calculation is performed using an absolute conversion coefficient, but it can also be performed using a relative conversion coefficient.

[0028] The state control unit 801 changes the operating state of the power conversion device 8 using the operating mode information Sm and the fault detection signal Sf output from the diagnostic unit 809, and outputs the current operating state to the PWM signal generation unit 804. Examples of the operating state include a PWM state, a three-phase short-circuit state, and a three-phase open state.

[0029] The target current calculation unit 802 calculates a target current value required for the motor 9 to output a torque equal to the target torque τs using the target torque τs, the DC voltage sensor value Vdc, and the motor angular velocity ω0. The target current value is output to the current control unit 803. The target current value is expressed, for example, in the form of a d-axis target current value and a q-axis target current value.

[0030] Using the target current value, the d-axis current value Id, the q-axis current value Iq, and the DC voltage sensor value Vdc, the current control unit 803 performs feedback control so that the d-axis current value Id and the q-axis current value Iq follow the target current value, and calculates three-phase duty cycles Du, Dv, and Dw for the three phases in PWM control. The duty cycles Du, Dv, and Dw are input to the PWM signal generation unit 804.

[0031] The PWM signal generation unit 804 switches the signal to be output to the driver circuit 81 according to the operating state output from the state control unit 801. The PWM signal generation unit 804 includes a timer (not shown) and generates a PWM signal pwm using the timer value and the duty cycles Du, Dv, and Dw in the respective phases output from the current control unit 803 when the operating state is a PWM state. Then, the PWM signal generation unit 804 outputs the generated PWM signal pwm to the driver circuit 81.

[0032] On the other hand, when the operating state is a three-phase open state, a PWM signal pwm is used to turn off all six power semiconductors 822 (see Fig. 3) is generated in the power conversion circuit 82. When the operating state is a three-phase short-circuit state, a PWM signal pwm for turning off all the upper-arm power semiconductors 822 and turning on all the lower-arm power semiconductors 822 among the six power semiconductors 822 in the power conversion circuit 82, or a PWM signal pwm for turning on all the upper-arm power semiconductors 822 and turning off all the lower-arm power semiconductors 822 is generated.

[0033] Based on the d-axis current value Id, the q-axis current value Iq, the motor angular velocity ω0, and the motor parameters R, Ld, Lq, and ϕ, the DC current calculation unit 807 calculates a d-axis voltage value Vd and a q-axis voltage value Vq according to the following equation (2). [Mathematical Formula 2] [VdVq]=[R+PLd−ωLqωLdR+PLq][IdIq]+[032ωϕ]

[0034] In equation (2), R represents a winding resistance of the motor 9, Ld represents a d-axis inductance value of the motor 9, Lq represents a q-axis inductance value of the motor 9, ω represents an electrical angular velocity of the motor 9, and ϕ represents a magnetic flux of the motor 9. The electrical angular velocity ω can be calculated by multiplying the motor angular velocity ω0 by the number of pole pairs of the motor. Note that P is a symbol representing a difference calculation.

[0035] The motor parameters R, Ld, Lq, and ϕ are set based on measurement results obtained in advance by measuring characteristics of the motor 9. In addition, the winding resistance value R and the magnetic flux ϕ also change depending on the temperature of the motor 9. Accordingly, according to the present embodiment, the winding resistance value R and the magnetic flux ϕ are corrected using the motor temperature sensor value Tm to improve the accuracy of the calculation. Under the condition that the d-axis current value Id and the q-axis current value Iq are substantially constant, the influence of the differential term on the calculation result is small. Accordingly, the calculation of the differential term can be omitted to reduce the computational burden.

[0036] Next, the DC current calculation unit 807 calculates a DC current calculation value Idc according to the following equation (3) based on the calculated d-axis voltage value Vd and q-axis voltage value Vq, the d-axis current value Id, the q-axis current value Iq, and the DC voltage sensor value Vdc. Equation (3) is derived from the relationship that the DC current input to the power conversion circuit 82 is substantially equal to the AC current output from the power conversion circuit 82. In equation (3), the numerator = Vdld + VqIq on the right side represents the AC current output from the power conversion circuit 82. The DC current calculation unit 807 outputs the calculated DC current calculation value Idc to the output torque calculation unit 808 and the external control device 6. [Mathematical Formula 3] Idc=VdId+VqIqVdc

[0037] In the calculation of the DC current calculation unit 807, the AC current is calculated using the d-axis current value Id and the q-axis current value Iq obtained by converting the actually measured AC current sensor values ​​Iu, Iv, and Iw, the d-axis current value Id and the q-axis current value Iq, and the d-axis voltage value Vd and the q-axis voltage value Vq calculated from Equation (2). Therefore, even if a fault occurs in the power conversion circuit 82 and it is unable to output an AC voltage and current corresponding to the duty cycles Du, Dv, and Dw output from the current control unit 803, the actual output AC current and the actual flowing DC current can be correctly calculated.

[0038] The output torque calculation unit 808 calculates the output torque τ output by the motor 9 based on the DC voltage sensor value Vdc, the DC current calculation value Idc, and the motor angular velocity ω0. The calculated output torque τ is output to the diagnostic unit 809 and the external control device 6.

[0039] The diagnostic unit 809 diagnoses a fault within the power conversion device 8. When a fault is detected by diagnosis, the diagnostic unit 809 outputs the details of the fault location as a fault detection signal Sf to the state control unit 801 and the external fault notification device 7. For example, when the output torque τ deviates from the target torque τs by at least a certain amount as a result of the comparison between the output torque τ and the target torque τs, the diagnostic unit 809 determines that a fault has occurred. Of course, the diagnosis performed by the diagnostic unit 809 is not limited to this, and the diagnosis of the sensor and the power conversion circuit 82 is performed using various sensor values, but a detailed description thereof will be omitted.

[0040] On the other hand, in a case where it is desired to continue driving the vehicle 1 even after a failure occurs in the power conversion circuit 82, a function for detecting the occurrence of another failure and safely stopping the vehicle 1 is required to ensure safety. As described above, according to the present embodiment, even if a failure occurs in the power conversion circuit 82, a direct current can be correctly calculated, and an output torque τ of the motor 9 can also be correctly calculated. Therefore, the diagnostic unit 809 can diagnose a deviation between the target torque τs and the output torque τ even after the failure. In this way, if another failure occurs after the failure of the power conversion circuit 82, this failure can be detected by the diagnostic unit 809.Accordingly, the driving of the vehicle 1 can be continued even after the failure of the power conversion circuit 82 occurs, while some functions such as emergency braking are impaired.

[0041] In addition, in a case where another drive device such as an internal combustion engine is mounted on the vehicle 1, which is a hybrid vehicle or the like, it is necessary to coordinately control the output torques of the multiple drive devices. According to the present embodiment, the correct output torque τ can be transmitted to the external control device 6 even after a failure occurs in the power conversion circuit 82. Therefore, even after the failure occurs in the power conversion circuit 82, the control device 6 can continue cooperative control with another drive device based on the output torque τ. (Second embodiment)

[0042] Fig. Fig. 5 is a diagram showing a second embodiment of the present invention, and is a control block diagram of the control circuit 80 similar to the one described above. Fig. 4. The components except for the control circuit 80 are identical to those according to the first embodiment. In addition, Fig. 5 Components identical to those according to the first embodiment are denoted by the same reference numerals, and differences will be mainly described below.

[0043] According to the second embodiment, the control circuit 80 has, in addition to the Fig. 4, the DC current calculation unit 810 further includes a DC current calculation unit 810 and a selection unit 811. The DC current calculation unit 810 calculates a DC current calculation value Idc similarly to the first embodiment according to equations (2) and (3). On the other hand, unlike the DC current calculation unit 817, the DC current calculation unit 810 calculates a DC current calculation value Idc according to the following equation (4) using the AC sensor values ​​Iu, Iv, and Iw measured by the AC current sensor 84. [Mathematical Formula 4] Idc=DuIu+DvIv+DwIw

[0044] In Equation (4), Du, Dv, and Dw are duty cycles generated by the current control unit 803 in the U-phase, V-phase, and W-phase, respectively. The AC sensor values ​​Iu, Iv, and Iw and the duty cycles Du, Dv, and Dw are input to the DC current calculation unit 810, which calculates a DC current calculation value Idc based on Equation (4). Hereinafter, the DC current calculation value calculated by the DC current calculation unit 807 is represented by a reference symbol Idc1, and the DC current calculation value enriched by the DC current calculation unit 810 is represented by a reference symbol Idc2.

[0045] Idc1 is input from the DC current calculation unit 807 to the selection unit 811 as a DC current calculation value, and Idc2 is input from the DC current calculation unit 810 to the selection unit 811 as a DC current calculation value. In addition, the operating state (for example, a PWM state, a three-phase short-circuit state, or a three-phase open-circuit state) of the power conversion device 8 is input from the state control unit 801 to the selection unit 811. The selection unit 811 selects one of the DC current calculation values ​​Idc1 and Idc2 according to the operating state output from the state control unit 801 and outputs the selected value as the DC current calculation value Idc to the output torque calculation unit 808 or the external control device 6.

[0046] Fig. 6 is a diagram showing a correspondence between an operating state and a DC calculation value to be selected by the selecting unit 811. When the power conversion device 8 is in a PWM operating state, the DC calculation value Idc2 is selected. When the power conversion device 8 is in a three-phase open state or a three-phase short-circuit state, the DC calculation value Idc1 is selected.

[0047] As shown in Equation (2), the motor parameters R, Ld, Lq, and ϕ are used for the calculation of the DC current calculation unit 807. Therefore, the DC current calculation value Idc1 is likely to be affected by parameter deviations from the actual motor constants of the motor 9, and the accuracy of the DC current calculation value Idc1 may be lower than that of the DC current calculation value Idc2. Therefore, when the power conversion device 8 is in the PWM operating state, the DC current calculation value Idc2, which has higher calculation accuracy, is used.

[0048] When the power conversion device 8 is in the three-phase open state, all six power semiconductors 822 (see Fig. 3) off. Therefore, the duty cycles Du, Dv, and Dw in equation (4) are all 0, and the DC current calculation value Idc2 is 0 [A]. In addition, when the power semiconductors 822 of the upper arm are off in the three-phase short-circuit state, the duty cycles Du, Dv, and Dw are all 0, and the DC current calculation value Idc2 is 0 [A], as is the case in the three-phase open state. On the other hand, when the power semiconductors 822 of the upper arm are on in the three-phase short-circuit state, the duty cycles Du, Dv, and Dw are all 1, and the DC current value is the sum of the AC current sensor values ​​Iu, Iv, and Iw. However, according to Kirchhoff's law, the sum of the three-phase AC currents is 0 [A], so the DC current calculation value Idc2 in this case is also 0 [A].

[0049] In this way, the DC current calculation value Idc2 is always 0 [A] in the three-phase open state and the three-phase short-circuit state. Therefore, the DC current calculation value Idc2 can be more accurate if a small DC current actually flows. Therefore, in the three-phase open state and the three-phase short-circuit state, the DC current calculation value Idc1, which is a calculation result of the DC current calculation unit 807, is used. In this way, by providing the two DC current calculation units 807 and 810 and selecting and using a more accurate DC current calculation value according to the operating state of the power conversion device 8, a correct DC current value can be used.

[0050] On the other hand, when the DC calculation value to be used is switched by the selection unit 811, the switching operation may affect the calculation of the output torque if there is a large difference between the DC calculation value before switching and the DC calculation value after switching. Therefore, when the difference between the DC calculation value before switching and the DC calculation value after switching is greater than a predetermined value, the selection unit 811 switches to the DC calculation value Idc1 or Idc2 after outputting a value between the DC calculation value Idc1 and the DC calculation value Idc2, thereby reducing the influence of the switching operation.

[0051] Fig. Fig. 7 is a diagram showing an example of a switching operation performed by the selection unit 811. In Fig. In the switching example shown in Figure 7, the operating state entered until time t1 is the PWM operating state, and at time t2, the operating state is switched to the three-phase short-circuit state or the three-phase open-circuit state. Until time t1, the DC current calculation value Idc2 appropriate for the PWM operating state is selected.

[0052] At the next time t2, the operating state is switched to the three-phase short-circuit state or the three-phase open-circuit state. However, the selection unit 811 does not immediately switch the DC calculation value Idc to the DC calculation value Idc1, and outputs an average value (Idc1 + Idc2) / 2 of the DC calculation value Idc1 and the DC calculation value Idc2 as the DC calculation value Idc. Then, at the next time t3, the DC calculation value Idc is switched to the DC calculation value Idc1. In this way, the influence of the switching operation can be reduced by performing the switching operation in stages to reduce the difference before and after switching.

[0053] It should be noted that switching when in Fig. 7, the switching mode is not limited to this. For example, a larger number of stages can be provided for the transition from Idc2 to Idc1. In particular, as shown in Fig. As shown in Figure 8, the DC current value to be used can be switched from the DC calculation value Idc2 to the DC calculation value Idc1, while changing the ratio between Idc1 and Idc2 in multiple steps such as t1(0:10) → t2(2:8) → t3(5:5) → t4(8:2) → t5(10:0). This can further reduce the influence of the switching operation. (Third embodiment)

[0054] Fig. Fig. 9 is a diagram showing a third embodiment of the present invention, and is a control block diagram of the control circuit 80. The components except for the control circuit 80 are identical to those according to the second embodiment. Fig. In the configuration of the control circuit 80 according to the second embodiment described above, as shown in Fig. 5, the operating state (for example, a PWM state, a three-phase short-circuit state, or a three-phase open state) of the power conversion device 8 is input from the state control unit 801 to the selection unit 811. On the other hand, in the configuration shown in Fig. 9, information relating to a fault condition within the power conversion device 8 is input from the diagnostic unit 809 to the selection unit 811. Other configurations are similar to those of the control circuit 80 shown in Fig. 5 and described above. Differences from the second embodiment will be mainly described below.

[0055] The DC current calculation values ​​Idc1 and Idc2 are input to the selection unit 811 from the respective DC current calculation units 807 and 810, and the fault condition is input to the selection unit 811 from the diagnosis unit 809, as described above. The selection unit 811 selects one of the DC current calculation value Idc1, the DC current calculation value Idc2, and another alternative value according to the input fault condition. Then, the selection unit 811 outputs the selected value as the DC current calculation value Idc to the output torque calculation unit 808 and the external control device 6. Fig. 10 is a diagram to explain the operation of the dialing unit 811. In Fig. 10, it is determined according to a fault location whether the DC calculation units 807 and 810 are capable of calculation or not, and a value to be selected is described. (Case where a fault has occurred in the power conversion circuit 82)

[0056] First, a case where a fault has occurred in the power conversion circuit 82 will be described. If a fault has occurred in the power conversion circuit 82, the duty cycles Du, Dv, and Dw in equation (4) during the calculation by the DC current calculation unit 810 deviate from the actual on / off states of the power semiconductors 822, so that the DC current calculation value Idc2 is incorrect. On the other hand, the DC current calculation value Idc1, which is a calculation result of the DC current calculation unit 807, is correct because it is based on the actually measured AC sensor values ​​Iu, Iv, and Iw. Therefore, when a fault occurs in the power conversion circuit 82, the selecting unit 811 selects and outputs the DC current calculation value Idc1. (Case where an error has occurred in sensor 91, 92 or 83, and case where a deviation of an engine parameter has occurred)

[0057] Next, a case where a fault has occurred in the motor angle sensor 91, the motor temperature sensor 92, or the DC voltage sensor 83, or a case where the motor parameter R, Ld, Lq, or ϕ has deviated from the actual one will be described. In equation (1), an electrical angle θ is calculated from the motor angle sensor value θm measured by the motor angle sensor 91 to calculate a d-axis current value Id and a q-axis current value Iq. In equation (2), an electrical angular velocity ω is used based on the motor parameters R, Ld, Lq, and ϕ and the motor angle sensor value θm to calculate a d-axis voltage value Vd and a q-axis voltage value Vq. At this time, the winding resistance value R and the magnetic flux ϕ are corrected using the motor temperature sensor value Tm. In equation (3), the DC voltage sensor value Vdc is used to calculate a DC current calculation value Idc.

[0058] In this way, the measurement results of the motor angle sensor 91, the motor temperature sensor 92, and the DC voltage sensor 83, as well as the motor parameters R, Ld, Lq, and ϕ, are used to calculate the DC current calculation value Idc1. Therefore, if an error occurs in the motor angle sensor 91, the motor temperature sensor 92, or the DC voltage sensor 83, or if the motor parameter R, Ld, Lq, or ϕ deviates from the actual motor constant, the DC current calculation unit 807 cannot perform a correct calculation. In such a case, the selection unit 811 selects and outputs the DC current calculation value Idc2 input from the DC current calculation unit 810. (Case where an error has occurred in the AC sensor 84)

[0059] The AC sensor values ​​Iu, Iv, and Iw are used by both the DC current calculation unit 807 and the DC current calculation unit 810, as shown in equations (1) and (4). Therefore, if a fault occurs in the AC current sensor 84, both the DC current calculation units 807 and 810 cannot correctly calculate the DC current calculation values. Therefore, if a fault occurs in the AC current sensor 84, the selection unit 811 selects and outputs a predetermined alternative value.

[0060] Regarding the alternative value, it is predetermined that it is output by the selecting unit 811 when the calculation results of the DC calculation units 807 and 810 are unreliable. In addition, to output the alternative value, reliability information may be output as a set along with the DC calculation value (Idc1 or Idc2). For example, as the reliability information, 1 is output when the DC calculation value is reliable, and 0 is output when the DC calculation value is unreliable.

[0061] In this way, by setting the alternative value in advance, if DC values ​​cannot be calculated correctly, the output torque calculation unit 808 and the external control device 6 can determine that the calculation result is unreliable when the alternative value is output. Then, in the subsequent process, it is possible to take measures, for example, not to use a DC calculation value.

[0062] As described above, according to the third embodiment, the selection unit 811 selects and outputs either the calculation result of the DC calculation unit 807 or 810 or the alternative information according to the fault condition of the power conversion device 8. This allows a DC calculation value to be appropriately used according to the fault condition. Furthermore, if the DC calculation values ​​Idc1 and Idc2 cannot be calculated, for example, if a fault occurs in the AC sensor 84, the use of the unreliable DC calculation value can be prevented by outputting the alternative value from the selection unit 811.

[0063] It should be noted that in each of the first to third embodiments described above, some or all of the above-described configurations, functions, processing units, and the like may be implemented in hardware, for example, by being designed as integrated circuits. Furthermore, each of the above-described configurations, functions, and the like may be implemented in software by a processor interpreting and executing a program that implements each function. Information such as programs, tables, and files for implementing the respective functions may be stored in a recording device such as a memory, a hard disk, or a solid state drive (SSD), or in a recording medium such as a smart card or a DVD.

[0064] According to the above-described first to third embodiments of the present invention, the following effects are achieved.

[0065] (C1) As in the Fig. 2 and Fig. 4, etc., a power conversion device 8 includes: a power conversion circuit 82 that converts a direct current into an alternating current by PWM control and outputs three-phase alternating currents to a motor 9, a three-phase / two-phase conversion unit 805 that converts the three-phase alternating currents Iu, Iv, and Iw into dq-axis currents (d-axis current Id and q-axis current Iq), a DC voltage detection unit (a DC voltage sensor 83) that detects a DC voltage value Vdc of the direct current, and a first calculation unit (DC current calculation unit 807) that calculates dq-axis voltages (d-axis voltage Vd and q-axis voltage Vq) based on motor parameters of the motor 9 and the dq-axis currents Id and Iq are calculated and a first DC current value (DC calculation value Idc1) of the DC current is calculated based on the dq-axis voltages Vd and Vq, the dq-axis currents Id and Iq, and the DC voltage value Vdc.

[0066] As described above, because the DC current calculation value Idc1 is calculated based on the motor parameters, the actually measured three-phase alternating currents Iu, Iv, and Iw, and the DC voltage value Vdc, a correct DC current value can be calculated during normal operation (during PWM operation, three-phase open-circuit operation, or three-phase short-circuit operation) or even when a fault occurs in the power conversion circuit 82. This allows any process using a DC current value to be properly executed.

[0067] (C2) In (C1), the DC calculation unit 807 calculates as in Fig. 4, etc., the DC current calculation unit 807 calculates the DC current calculation value Idc1 at least when a fault has occurred in a switching element (power semiconductor 822) provided in the power conversion circuit 82. In this way, when a fault has occurred in the power semiconductor 822 provided in the power conversion circuit 82, the DC current calculation unit 807 calculates the DC current calculation value Idc1, thereby enabling the calculation of a correct DC current value.

[0068] (C3) In (C1), the power conversion device 8, as shown in the Fig. 5 and Fig. 9, etc., further comprises: an AC detection unit (an AC sensor 84) that detects AC values ​​(AC sensor values ​​Iu, Iv, and Iw) of the three-phase AC currents, and a second calculation unit (DC calculation unit 810) that calculates a second DC value (DC calculation value Idc2) of the DC current based on the three-phase duty cycles Du, Dv, and Dw in the PWM control of the AC sensor values ​​Iu, Iv, and Iw, wherein one of the DC calculation values ​​Idc1 and Idc2 is selected and used according to an operation state and / or fault state of the power conversion device 8.

[0069] Therefore, when the DC current calculation value Idc1 cannot be calculated correctly (when an error has occurred in the motor angle sensor 91, the motor temperature sensor 92, or the DC voltage sensor 83, or when a motor parameter deviates from the actual parameter) or when the calculation accuracy is poor (PWM operation), the DC current calculation value Idc2 is selected and used. On the other hand, when the DC current calculation value Idc2 cannot be calculated correctly (in a three-phase open state, a three-phase short-circuit state, or when a failure has occurred in the power conversion circuit 82), the DC current calculation value Idc1 is selected and used. In this way, by selecting and using one of the DC current calculation values ​​Idc1 and Idc2 according to the operating state and / or the failure state of the power conversion device 8, a DC current value can be correctly calculated in various states.

[0070] (C4) In (C3), the power conversion device 8, as shown for example in the Fig. 5 and Fig. 6, etc., when the operating state of the power conversion device 8 is a three-phase short-circuit state or a three-phase open state, the DC current calculation value Idc1 calculated by the DC current calculation unit 807 is extracted and used because the DC current calculation unit 810 cannot perform correct calculation.

[0071] (C5) In (C3), the power conversion device 8, as shown in the Fig. 9 and Fig. 10, etc., when an error has occurred in the power conversion circuit 82, the DC calculation value Idc1 calculated by the DC calculation unit 807 is output and used because the DC calculation unit 810 cannot perform a correct calculation.

[0072] (C6) In (C3) the motor 9, as shown in the Fig. 2, Fig. 9 and Fig. 10, etc., a motor angle sensor 91 that measures the motor rotation angle (motor angle sensor value θm) and a motor temperature sensor 92 that measures the motor temperature (motor temperature sensor value Tm), and when an error has occurred in any one of the DC voltage detection unit (DC voltage sensor 83), the motor angle sensor 91, and the motor temperature sensor 92, the power conversion device 8 selects and uses the DC current calculation value Idc2 calculated by the DC current calculation unit 810 because the DC current calculation unit 807 in the power conversion device 8 cannot perform correct calculation.

[0073] (C7) In (C3) the power conversion device 8, as shown in the Fig. 9 and Fig. 10, etc., when an error has occurred in the AC current detection unit (AC sensor 84), alternative information is output to notify that the DC current calculation values ​​Idc1 and Idc2 are unreliable, instead of using the DC current calculation values ​​Idc1 and Idc2, because the DC current calculation units 807 and 810 cannot correctly calculate DC current values. For example, instead of the DC current calculation values ​​Idc1 and Idc2, an alternative value (a value defined as unreliable) is output from the selection unit 811.

[0074] (C8) In (C3), as in Fig. 7 etc., when a DC current value to be used is switched from the DC current calculation value Idc1 to the DC current calculation value Idc2 or from the DC current calculation value Idc2 to the DC current calculation value Idc1 according to the operation state and / or fault state of the power conversion device 8, the DC current value to be used after changing is changed to a third DC current value between the DC current calculation value Idc2 and the DC current calculation value Idc1 to the DC current value after switching.

[0075] For example, as in Fig. In the example shown in Figure 7, the third DC current value is set to an average value = (Idc1 + Idc2) / 2. By changing the DC current value to be used in this way, the DC current value changes gradually over time when switching is performed, so that the influence of the switching operation can be reduced.

[0076] (C9) Furthermore, in (C8), as in Fig. 8, several third DC values ​​with different amounts can be set at times t2 to t4 of the switching section, and the DC value to be used can be changed stepwise from the DC calculation value Idc1 before switching to the DC calculation value Idc2 after switching. In Fig. 8, the ratios between Idc1 and Idc2 at t2, t3, and t4 are set as (2:8), (5:5), and (8:2), respectively. In this way, the change in the DC current value between times can be made more gradual by changing the DC current value to be used in several stages from the DC current calculation value Idc2 to the DC current calculation value Idc1. This can reduce the influence of the switching operation.

[0077] (C10) As in the Fig. 2 and Fig. 3, etc., a drive device 2 includes a motor 9 and the above-described power conversion device 8 shown in (C1), which converts a direct current into an alternating current through PWM control and supplies three-phase alternating currents to the motor 9. As described in (C1), the power conversion device 8 included in the drive device 2 can calculate a correct direct current value during normal operation (during PWM operation, three-phase open operation, or three-phase short-circuit operation) or even when a fault occurs in the power conversion circuit 82. This allows a process executed using a direct current value to be properly executed in the drive device 2.

[0078] The embodiments described above serve only as examples, and the present invention is not limited thereto as long as the features of the invention are not impaired. Other aspects conceivable within the technical spirit of the present invention also fall within the scope of the present invention. In addition, part of the configuration of one embodiment may be replaced by the configuration of another embodiment, and the configuration of one embodiment may be added to the configuration of another embodiment. For example, the selection unit 811 may be configured by inputting not only the error state from the diagnosis unit 809 but also the operating state from the state control unit 801, as shown in Fig. 5, into the selection unit 811 from Fig.9 make a selection based on both the fault condition and the operating condition. In addition, a portion of the configuration of each embodiment may be added to another configuration, a portion of the configuration of each embodiment may be removed from another configuration, or a portion of the configuration of each embodiment may replace another configuration. List of reference symbols 1 vehicle 2 drive device 5 DC power supply 6 Control device 7 Error notification device 8 Power conversion device 9 Engine 80 control circuit 81 Driver circuit 82 Power conversion circuit 83 DC voltage sensor 84 AC sensor 91 Engine angle sensor 92 Engine temperature sensor 801 State control unit 802 Target current calculation unit 803 Power control unit 804 PWM signal generation unit 805 Three-phase / two-phase conversion unit 806 Engine speed calculation unit 807, 810 DC calculation unit 808 Output torque calculation unit 809 Diagnostic Unit 811 dialing unit 822 power semiconductors QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] JP 2006-33970 A

[0003] JP 2017-208893 A

[0003]

Claims

[1] Power conversion device, comprising: a power conversion circuit that converts a direct current into an alternating current through PWM control and outputs three-phase alternating currents to a motor, a three-phase / two-phase conversion unit that converts the three-phase alternating currents into dq-axis currents, a DC voltage detection unit that detects a DC voltage value of the AC current, and a first calculation unit that calculates dq-axis voltages based on motor parameters of the motor and the dq-axis currents, and calculates a first DC value of the DC current based on the dq-axis voltages, the dq-axis currents, and the DC voltage value. [2] The power conversion device according to claim 1, wherein the first calculation unit calculates the first DC current value at least when a fault has occurred in a switching element provided in the power conversion circuit. [3] The power conversion device according to claim 1, further comprising: an AC current detection unit that detects AC values ​​of the three-phase alternating currents, and a second calculation unit that calculates a second DC value of the DC current based on three-phase duty cycles in the PWM control and the AC values, wherein one of the first DC current value and the second DC current value is selected and used according to an operating state and / or a fault state of the power conversion device. [4] The power conversion device according to claim 3, wherein the first DC current value calculated by the first calculation unit is selected and used when the operating state is a three-phase short-circuit state or a three-phase open state. [5] The power conversion device according to claim 3, wherein the first DC current value calculated by the first calculation unit is selected and used when a fault has occurred in the power conversion device. [6] Power conversion device according to claim 3, wherein the motor has a motor angle sensor that measures the motor rotation angle and a motor temperature sensor that measures the motor temperature, and the second DC current value calculated by the second calculation unit is selected and used when an error has occurred in one of the DC voltage detection unit, the motor angle sensor and the motor temperature sensor. [7] The power conversion device according to claim 3, wherein alternative information for notifying that the first and second DC values ​​are not reliable is used instead of the first and second DC values ​​when a failure has occurred in the AC detection unit. [8] Power conversion device according to claim 3, wherein when, according to the operating state and / or the fault state of the power conversion device, a DC value to be used is switched from the first DC value to the second DC value or from the second DC value to the first DC value, the DC value to be used after changing to a third DC value between the first and second DC values ​​is changed to the DC value after switching. [9] The power conversion device according to claim 8, wherein a plurality of the third DC current values ​​are set to different amounts, and the DC current value to be used is changed stepwise from the DC current value before switching to the DC current value after switching. [10] Drive device, comprising: an engine and The power conversion device according to claim 1, which converts a direct current into an alternating current by PWM control and supplies three-phase alternating currents to the motor.

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