Motor Control Device

Abstract

This motor control device comprises: a boost converter having a reactor and a smoothing capacitor and boosting the voltage of a battery in a vehicle; at least one drive device for driving a traveling motor of the vehicle by the power from the boost converter; at least one AC / DC converter for converting the current generated by a motor generator mounted on the vehicle to DC current; and a control unit for controlling the drive device and the AC / DC converter. The control unit can perform shift operation for shifting the resonant frequency of a circuit having the reactor and the smoothing capacitor when operating the drive device in a state in which current flows from the drive device to the reactor, wherein the shift operation shifts the resonant frequency by operating the AC / DC converter and flowing the DC current to the reactor.

Description

[Technical field]

[0001] The present invention relates to a motor control device. [Background technology]

[0002] Conventionally, there has been a motor control device that converts power from a boost converter that boosts the voltage of a battery into AC power using a drive device (e.g., an inverter) and supplies the AC power to the vehicle's driving motor, thereby driving the driving motor.

[0003] The boost converter may have a switching leg, a reactor, and a smoothing capacitor. When a current flows from a drive device to a reactor, such as when an upper arm of a switching leg is controlled to an on state, and the running motor is rotating, a ripple current generated according to the rotation speed of the motor may cause resonance in a circuit (e.g., an LC circuit) having a reactor and a smoothing capacitor.

[0004] Therefore, Patent Document 1 discloses that the upper arm is turned off to cut off the path from the drive device to the reactor, thereby suppressing the above-mentioned resonance of the boost converter. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2012-070473 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, if the path from the drive device to the reactor is blocked, regenerative braking may not be possible.

[0007] " The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a motor control device that is capable of using regenerative braking while suppressing resonance of a boost converter. [Means for solving the problem]

[0008] (1) One aspect of the present invention includes a boost converter having a reactor and a smoothing capacitor, and boosting a voltage of a battery in a vehicle, at least one drive device that drives a traction motor of the vehicle with power from the boost converter, at least one AC / DC converter that converts a current generated by a motor generator mounted on the vehicle into a DC current, and a control unit that controls the drive device and the AC / DC converter, wherein the control unit is capable of executing a shift operation to shift a resonant frequency of a circuit having the reactor and the smoothing capacitor when the drive device is operated in a state where a current flows from the drive device to the reactor, The shift operation is a motor control device that operates the AC / DC converter to cause the DC current to flow through the reactor, thereby shifting the resonant frequency.

[0009] (2) In the motor control device of (1) above, the boost converter has upper arm and lower arm switching elements, the reactor has a first end connected to the battery and a second end connected to a connection point between the upper arm and the lower arm, and the smoothing capacitor is connected to the upper arm, and when an abnormality occurs in the boost converter, the control unit may control the upper arm to always be on while keeping the lower arm in an off state, thereby causing current to flow from the drive device to the reactor.

[0010] (3) In the motor control device of (1) or (2) above, the shift operation may shift the resonant frequency to a higher frequency by operating the AC / DC converter to pass the DC current through the reactor.

[0011] (4) In any of the motor control devices described in (1) to (3) above, the control unit determines whether the vehicle speed of the vehicle is within a predetermined range, and performs the shift operation if the vehicle speed is within the predetermined range, and the predetermined range may include a vehicle speed range corresponding to a frequency band in which the circuit resonates.

[0012] (5) In the motor control device of (4) above, the resonant frequency after the shift operation is performed may not be included in the frequency band before the shift operation is performed.

[0013] (6) In any one of the motor control devices described in (1) to (5) above, the control unit may control the AC / DC converter based on a current value flowing through the reactor or a current value flowing through the battery during the shift operation.

[0014] (7) In the motor control device according to any one of (1) to (6) above, the boost converter may be a single chopper type boost chopper circuit.

[0015] (8) In any of the motor control devices described in (1) to (3), the shift operation may be performed when the frequency of a ripple current flowing through the smoothing capacitor by at least the traction motor is included in a predetermined frequency band range including the resonant frequency before the shift operation is performed. Effect of the Invention

[0016] As described above, according to the present invention, it is possible to provide a motor control device that is capable of using regenerative braking while suppressing resonance of a boost converter. [Brief description of the drawings]

[0017] [Figure 1] 1 is a diagram illustrating an example of a schematic configuration of a motor control device according to a first embodiment. [Diagram 2] 1 is a diagram illustrating an example of the configuration of a vehicle according to a first embodiment. [Diagram 3] FIG. 3 is a diagram illustrating a Bode plot showing a frequency response of a ripple voltage according to the first embodiment. [Figure 4] FIG. 13 is a diagram showing frequency responses of two ripple voltages before and during a shift operation. [Diagram 5] 4 is a flow diagram of the operation of a control unit according to the first embodiment. FIG. [Figure 6] 5A to 5C are diagrams illustrating a shift operation according to the first embodiment. [Figure 7] FIG. 11 is a diagram illustrating an example of a schematic configuration of a motor control device according to a second embodiment. [Figure 8] FIG. 11 is a flow chart of the operation of a control unit according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention. In the drawings, the same or similar parts may be given the same reference numerals, and duplicated explanations may be omitted. In addition, the shapes and sizes of elements in the drawings may be exaggerated for clearer explanation.

[0019] The "connection" described below is an electrical connection. An electrical connection is a connection that allows an electrical signal to be transmitted directly or indirectly. The electrical connection may be a connection via a component such as a cable, a resistor, a capacitor, a diode, or a switch.

[0020] <First embodiment> Fig. 1 is a diagram showing an example of a schematic configuration of a motor control device 3 according to a first embodiment. Fig. 2 is a diagram showing an example of a configuration of a vehicle 100 according to the first embodiment. The motor control device 3 is mounted on the vehicle 100. The vehicle 100 may be a four-wheeled vehicle or a two-wheeled vehicle. The vehicle 100 is, for example, a hybrid vehicle.

[0021] As shown in FIG. 1, a vehicle 100 includes at least one traction motor 1, at least one motor generator 2, and a motor control device 3.

[0022] The traction motor 1 is an electric motor for propelling the vehicle 100, and is a so-called traction motor. The traction motor 1 is a motor connected to the drive wheels 130. The rotation speed of the traction motor 1 is linked to the vehicle speed. In the example shown in Fig. 1, the traction motor 1 is a three-phase (U, V, W) motor.

[0023] The motor generator 2 is a motor mounted on the vehicle 100. The motor generator 2 generates electric power (hereinafter referred to as "generated electric power") by being driven by an engine 110 of the vehicle 100. The generated electric power by the motor generator 2 is stored in a battery 120 mounted on the vehicle 100. The generated electric power by the motor generator 2 may be supplied to the driving motor 1. In the example shown in FIG. 1, the motor generator 2 is a three-phase motor.

[0024] The motor control device 3 drives the traveling motor 1 and the motor generator 2. The motor control device 3 drives the traveling motor 1 and stores electric power generated by regenerative braking of the traveling motor 1 (hereinafter referred to as "regenerative power") in a battery 120. The motor control device 3 stores the generated electric power generated by the motor generator 2 in the battery 120 and supplies it to the traveling motor 1.

[0025] 1 is a diagram showing an example of a schematic configuration of a motor control device 3 according to a first embodiment. As shown in FIG 1, the motor control device 3 includes a capacitor 10, a boost converter 20, a drive device 30, an AC / DC converter 40, and a control unit 50.

[0026] The capacitor 10 is a smoothing capacitor provided on the primary side of the boost converter 20. For example, a first terminal of the capacitor 10 is connected to a positive terminal P1 of the battery 120. A second terminal of the capacitor 10 is connected to a negative terminal P2 of the battery 120. The negative terminal P2 of the battery 120 is grounded. The capacitor 10 is provided between the battery 120 and the boost converter 20.

[0027] The boost converter 20 boosts the output voltage VBAT output from the battery 120 at a predetermined boost ratio. The voltage boosted by the boost converter 20 is input to the drive device 30. The boost converter 20 generates a predetermined voltage Vs by boosting the output voltage VBAT output from the battery 120 at a predetermined boost ratio, and outputs the voltage Vs to the drive device 30. The boost converter 20 may further include a function of stepping down a voltage (hereinafter referred to as a "regenerative voltage") supplied from the drive device 30 at a predetermined step-down ratio and outputting the voltage to the battery 120. That is, the boost converter 20 may be a step-up / step-down converter. The regenerative voltage is a voltage generated by regenerative braking of the traveling motor 1. The boost converter 20 may be a single-phase converter or a multi-phase converter. In the example shown in FIG. 1, the boost converter 20 is a single chopper type boost chopper circuit.

[0028] An example of a schematic configuration of the boost converter 20 will be described below.

[0029] The boost converter 20 includes a reactor 21, a switching element Q1, a switching element Q2, and a capacitor 22.

[0030] A first terminal of the reactor 21 is connected to a first terminal of the capacitor 10. A second terminal of the reactor 21 is connected to a connection point X between the switching element Q1 and the switching element Q2.

[0031] The switching element Q1 and the switching element Q2 are connected in series to each other.

[0032] Although a case will be described in which the switching elements Q1 and Q2 are IGBTs (Insulated Gate Bipolar Transistors), the present invention is not limited to this and may be, for example, FETs (Field Effective Transistors) or the like.

[0033] The collector of the switching element Q1 is connected to a first terminal of the capacitor 22. The emitter of the switching element Q1 is connected to a second terminal of the reactor 21. The gate of the switching element Q1 is connected to the control unit 50. The switching element Q1 may be referred to as an upper arm.

[0034] The collector of the switching element Q2 is connected to the second terminal of the reactor 21. The emitter of the switching element Q2 is connected to the negative terminal P2 of the battery 120. The gate of the switching element Q2 is connected to the control unit 50. The boost converter 20 includes diodes connected in parallel in the reverse direction to each of the switching element Q1 and the switching element Q2. The collector of the switching element Q1 is connected to the cathode of the diode D1, and the emitter of the switching element Q1 is connected to the anode of the diode D1. The collector of the switching element Q2 is connected to the cathode of the diode D2, and the emitter of the switching element Q2 is connected to the anode of the diode D2.

[0035] The capacitor 22 is connected to the secondary side (the drive device 30 side) of the boost converter 20. The capacitor 22 is a smoothing capacitor having a first terminal connected to the collector of the upper switching element Q1 and a second terminal connected to the negative terminal P2 of the battery 120.

[0036] The drive device 30 drives the driving motor 1 of the vehicle 100 with power from the boost converter 20. The drive device 30 converts a predetermined voltage Vs boosted by the boost converter 20 into an AC voltage. The drive device 30 supplies the converted AC voltage to the driving motor 1. The drive device 30 converts an AC voltage generated by regenerative braking of the driving motor 1 into a DC voltage, and supplies the converted DC voltage to the boost converter as a regenerative voltage. The drive device 30 is, for example, a three-phase inverter, and has three switching legs corresponding to each phase. The operation of the drive device 30 is controlled by a control unit 50.

[0037] In the example shown in FIG. 1, the drive device 30 includes a switching leg 31, a switching leg 32, and a switching leg 33.

[0038] The switching leg 31 includes a switching element 31a which is an upper arm and a switching element 31b which is a lower arm. The switching leg 32 includes a switching element 32a which is an upper arm and a switching element 32b which is a lower arm. The switching leg 33 includes a switching element 33a which is an upper arm and a switching element 33b which is a lower arm. The switching elements 31a, 31b, 32a, 32b, 33a, and 33b are, for example, IGBTs or FETs, and are controlled by the control unit 50.

[0039] The AC / DC converter 40 converts the current generated by the motor generator 2 mounted on the vehicle 100 into a DC current. In other words, the AC / DC converter 40 converts the three-phase AC power generated by the motor generator 2 into a DC power. The AC / DC converter 40 has three switching legs corresponding to each phase. The operation of the AC / DC converter 40 is controlled by a control unit 50.

[0040] In the example shown in FIG. 1, the AC / DC converter 40 includes a switching leg 41, a switching leg 42, and a switching leg 43.

[0041] The switching leg 41 includes a switching element 41a which is an upper arm and a switching element 41b which is a lower arm. The switching leg 42 includes a switching element 42a which is an upper arm and a switching element 42b which is a lower arm. The switching leg 43 includes a switching element 43a which is an upper arm and a switching element 43b which is a lower arm. The switching elements 41a, 41b, 42a, 42b, 43a, and 43b are, for example, IGBTs or FETs, and are controlled by the control unit 50.

[0042] The control unit 50 performs inverter control to control the drive device 30 based on command values ​​such as a torque command value. This inverter control can be performed using known techniques. The control unit 50 controls the AC / DC converter 40 to convert the current generated by the motor generator 2 into a DC current.

[0043] The control unit 50 controls the boost converter 20. The control unit 50 performs converter control to control each of the upper arm switching element Q1 and the lower arm switching element Q2 to an on state or an off state. The control unit 50 may be a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The control unit 50 may further include a non-volatile or volatile semiconductor memory (e.g., a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), or an EEPROM (Electrically Erasable Programmable Read Only Memory)). For example, the control unit 50 may be a microcontroller such as an MCU. The control unit 50 may have driver circuits for the boost converter 20, the drive device 30, and the AC / DC converter 40.

[0044] The control unit 50 can execute an operation (hereinafter referred to as a "fail-safe operation") of controlling the switching element Q1 of the upper arm to be constantly on to drive the drive device 30. In the fail-safe operation, the switching element Q2 of the lower arm is in an off state. The control unit 50 A fail-safe operation is performed when some factor, such as an abnormality occurring in the boost converter 20 or an abnormality occurring in a sensor mounted on the vehicle 100, causes a hindrance to the running of the vehicle 100 or there is a possibility that a hindrance to the running of the vehicle 100 may occur. However, this is not limited to this, and the timing at which the control unit 50 performs the fail-safe operation is not particularly limited and can be set arbitrarily. By performing the fail-safe operation, when some abnormality occurs in the vehicle 100, the vehicle 100 can continue to run safely without immediately stopping the vehicle 100. Note that an abnormality in the boost converter 20 includes a failure of the boost converter 20.

[0045] In the fail-safe operation, the upper arm switching element Q1 is constantly on, and therefore the second terminal of the reactor 21 and the first terminal of the capacitor 22 are electrically connected to each other. In other words, in the fail-safe operation, the upper arm switching element Q1 is constantly on, and therefore a current flows from the drive device 30 to the reactor 21.

[0046] When the switching element Q1 of the upper arm is in the off state, a current flows from the reactor 21 through the diode D1 to the capacitor 22 and the drive device 30. However, when the switching element Q1 of the upper arm is in the off state, no current flows from the capacitor 22 or the drive device 30 to the reactor 21.

[0047] During the fail-safe operation, resonance may occur in the boost converter 20. When the switching element Q1 of the upper arm is always on, the reactor 21 and the capacitor 22 are directly connected to each other, so that an LC circuit including the reactor 21 and the capacitor 22 is formed.

[0048] During fail-safe operation, the drive device is operating, and therefore the traction motor 1 is rotating. This rotation of the traction motor 1 generates a ripple current in the capacitor 22. If the frequency of this ripple current approaches the resonant frequency fr of the LC circuit including the reactor 21 and the capacitor 22, the LC circuit may resonate. This resonance of the LC circuit may lead to an increase in the ripple voltage at the first end of the capacitor 22. This may cause excessive torque ripple to be generated in the traction motor. The resonance of the LC circuit may be referred to as the resonance of the boost converter 20.

[0049] 3 is a diagram showing a Bode diagram illustrating the frequency response of the ripple voltage appearing at the first end of the capacitor 22 according to the first embodiment. The Bode diagram shown in FIG. 3 is a diagram illustrating an example of a Bode diagram in which the vertical axis represents gain G and the horizontal axis represents frequency f. The gain G is the gain when the ripple current flowing through the capacitor 22 is the input and the ripple voltage of the capacitor 22 is the output. The Bode diagram shown in FIG. 3 shows the change in gain G with respect to frequency f.

[0050] When the rotation speed of the traveling motor 1 varies, the frequency of the ripple current also varies. That is, when the rotation speed of the traveling motor 1 increases, the frequency of the ripple current also increases. When the frequency of the ripple current exceeds the frequency fx at which the gain G is 0 [dB], resonance of the boost converter 20 may occur. In the first embodiment, the frequency band at which the gain G exceeds 0 [dB] is called the resonance band. In the example shown in FIG. 3, the frequency band from frequency f1 to frequency f2 is the resonance band. When the frequency of the ripple current becomes the resonance frequency fr, the gain G becomes maximum and the ripple voltage at the first end of the capacitor 22 becomes maximum.

[0051] During the fail-safe operation, an LC circuit including the reactor 21 and the capacitor 22 is formed, and the traveling motor 1 is rotating. Therefore, during the fail-safe operation, resonance of the boost converter 20 may occur. The control unit 50 executes a shift operation to shift the resonance frequency fr in order to suppress resonance of the boost converter 20 during the fail-safe operation. The shift operation is an operation in which the AC-DC converter 40 is operated to pass the DC current converted by the AC-DC converter 40 to the reactor 21. When the DC current is superimposed on the reactor 21, the inductance of the reactor 21 decreases. The resonance frequency fr is calculated from the inductance of the reactor 21 and the capacitance of the capacitive component having the capacitor 22. Therefore, when the inductance of the reactor 21 changes, the resonance frequency fr also changes. Specifically, when the inductance of the reactor 21 decreases, the resonance frequency fr changes to the high frequency side. In other words, the resonance band shown in FIG. 3 changes to the high frequency side.

[0052] Figure 4 shows the frequency response of two ripple voltages before and during a shift operation. The solid line in Figure 4 shows the frequency response of the ripple voltage before a shift operation is performed. The dotted line in Figure 4 shows the frequency response of the ripple voltage during a shift operation.

[0053] As shown in FIG. 4, when the shift operation is performed, the resonant frequency of the LC circuit changes from the resonant frequency fr before the shift operation to a resonant frequency fr' (>fr). Therefore, the resonant band changes from a frequency band H1 from frequency f1 to frequency f2 to a frequency band H2 from frequency f11 (>f1) to frequency f12 (>f2). The frequency band H2 is a frequency band higher than the frequency band H1. In the first embodiment, the resonant frequency fr' is set to a frequency not included in the frequency band H1. In other words, the resonant frequency fr' is set to a frequency higher than the frequency f12. However, the present invention is not limited to this, and the resonant frequency fr' may be any frequency higher than the resonant frequency fr.

[0054] The frequency band H1 and the frequency band H2 may partially overlap. That is, the frequency band H2 may include at least a frequency band higher than the frequency band H1. The frequency band H2 may not include the entire frequency band H1.

[0055] The timing at which the shift operation is performed is not particularly limited and can be set arbitrarily. For example, it is sufficient that the shift operation is performed at least when the frequency of the ripple current is included in the frequency band H1. Information on the frequency band H1 is stored in the control unit 50 in advance.

[0056] For example, the control unit 50 executes a shift operation when a predetermined condition (hereinafter referred to as a "control condition") that has been set in advance is satisfied. This predetermined condition can be set arbitrarily. The predetermined condition may be set based on the resonance frequency fr. For example, the control condition may be that the frequency of the ripple current is included in the frequency band H1. The control unit 50 may directly or indirectly determine whether the frequency of the ripple current is included in the frequency band H1.

[0057] The frequency of the ripple current is correlated with the rotation speed of the driving motor 1. Therefore, the control unit 50 may determine, as a control condition, whether or not the rotation speed N of the driving motor 1 is within the range of the rotation speed N1 to the rotation speed N2. If the control unit 50 determines that the rotation speed N of the driving motor 1 is within the range of the rotation speed N1 to the rotation speed N2, the control unit 50 may determine that the frequency of the ripple current is included in the frequency band H1. In other words, if the control unit 50 determines that the rotation speed N of the driving motor 1 is within the range of the rotation speed N1 to the rotation speed N2, the control unit 50 may execute a shift operation. The rotation speed N1 is the rotation speed corresponding to the frequency f1. The rotation speed N2 is the rotation speed corresponding to the frequency f2.

[0058] The rotation speed of the driving motor 1 is correlated with the vehicle speed of the vehicle 100. In other words, the frequency of the ripple current has a one-to-one relationship with the vehicle speed of the vehicle 100, and is correlated. Therefore, the control unit 50 may determine, as a control condition, whether or not the vehicle speed V of the vehicle 100 is within a range from vehicle speed V1 to vehicle speed V2. Then, when the control unit 50 determines that the vehicle speed V of the vehicle 100 is within a range from vehicle speed V1 to vehicle speed V2, the control unit 50 may determine that the frequency of the ripple current is included in the frequency band H1. In other words, when the control unit 50 determines that the vehicle speed V of the vehicle 100 is within a range from vehicle speed V1 to vehicle speed V2, the control unit 50 may execute a shift operation. The vehicle speed V1 is a vehicle speed corresponding to a frequency f1. The vehicle speed V2 is a vehicle speed corresponding to a frequency f2.

[0059] The control condition may be that the frequency of the ripple current is included in a range from a frequency f0 to a frequency f2 that is lower than the frequency f1. For example, the control condition may be that the vehicle speed is included in a range from a vehicle speed V0 to a vehicle speed V2 that is lower than the vehicle speed V1. The control condition may be that the rotation speed N of the driving motor 1 is included in a range from a rotation speed N0 to a rotation speed N2 that is lower than the rotation speed N1. For example, the control condition may be that the frequency of the ripple current is included in a predetermined range that includes the entire frequency band H1. The control condition may be that the vehicle speed or the rotation speed of the driving motor 1 is included in a predetermined range that includes the entire range corresponding to the frequency band H1. The predetermined range may be a vehicle speed range corresponding to the frequency band H1, or a range that includes the entire vehicle speed range corresponding to the frequency band H1. The predetermined range may be a range of rotation speeds of the driving motor 1 corresponding to the frequency band H1, or a range that includes all rotation speeds of the driving motor 1 corresponding to the frequency band H1.

[0060] The operation of the control unit 50 according to the first embodiment will be described below. Fig. 5 is a flow diagram of the operation of the control unit 50 according to the first embodiment.

[0061] The control unit 50 determines whether or not the vehicle is in a fail-sale operation (step S101). When the control unit 50 determines that the vehicle is in a fail-sale operation, the control unit 50 determines whether or not a control condition is satisfied (step S102). For example, the control unit 50 determines whether or not the vehicle speed of the vehicle is within a predetermined range. This predetermined range is a vehicle speed range that corresponds to a frequency band including the resonance frequency fr.

[0062] When the vehicle speed is within a predetermined range, the control unit 50 determines that the control condition is satisfied. When the control unit 50 determines that the control condition is satisfied, the control unit 50 executes a shift operation to reduce the inductance of the reactor 21 (step S103). Specifically, the control unit 50 operates the AC / DC converter 40 to convert the generated current generated by the motor generator 2 into a DC current, and supplies the DC current to the reactor 21. In one example, the control unit 50 supplies the DC current converted by the AC / DC converter 40 to the battery 120 via the reactor 21. The shift operation in the first embodiment may be to store the generated power generated by the motor generator 2 in the battery 120 via a route that passes through the reactor 21.

[0063] When the control unit 50 determines that the control condition is not satisfied, the control unit 50 does not execute the shift operation. That is, the control unit 50 maintains the initial inductance of the reactor 21 by not executing the shift operation (step S104).

[0064] Next, the shift operation according to the first embodiment will be described with reference to Fig. 6. Fig. 6 is a diagram for explaining the shift operation according to the first embodiment.

[0065] When the drive device 30 is driven to operate the traction motor 1, if any abnormality occurs in the boost converter 20, the control unit 50 executes a fail-safe operation of controlling the upper arm switching element Q1 to be in a constantly on state. An example of an abnormality in the boost converter 20 is when the boost converter 20 cannot perform a boost operation.

[0066] In the fail-safe operation, the second terminal of the reactor 21 and the first terminal of the capacitor 22 are directly connected to each other. That is, when the second terminal of the reactor 21 and the first terminal of the capacitor 22 are directly connected to each other, a current flows in both directions between the second terminal of the reactor 21 and the first terminal of the capacitor 22.

[0067] The control unit 50 judges whether or not a control condition is satisfied when the fail-safe operation is being performed. When the control condition is satisfied when the fail-safe operation is being performed, the control unit 50 executes a shift operation. For example, the control unit 50 monitors the vehicle speed V of the vehicle 100 when the fail-safe operation is being performed. The control unit 50 judges whether or not the vehicle speed V of the vehicle 100 is within a predetermined range set in advance, and executes a shift operation when the vehicle speed V of the vehicle 100 is within the predetermined range set in advance. This shift operation is executed during the fail-safe operation.

[0068] The control unit 50 starts the operation of the AC / DC converter 40 to convert the generated current into a DC current Ir. As shown in Fig. 6, the control unit 50 supplies the DC current Ir to the battery 120 via the reactor 21. When the DC current Ir flows through the reactor 21, the inductance of the reactor 21 decreases, and the resonant frequency fr of the LC circuit included in the boost converter 20 changes to the high frequency side. When the resonant frequency fr of the LC circuit changes to the high frequency side, the resonance of the boost converter 20 is suppressed.

[0069] In the first embodiment, even when a shift operation is being performed, the second terminal of the reactor 21 and the first terminal of the capacitor 22 are directly connected. That is, the control unit 50 suppresses resonance of the boost converter 20 with the upper arm switching element Q1 always kept in the on state. Therefore, even when a shift operation is being performed, the control unit 50 can regenerate the electric power generated by the regenerative braking of the driving motor 1 to the battery 120.

[0070] As described above, the motor control device 3 according to the first embodiment includes the boost converter 20, one or more drive devices 30, one or more AC / DC converters 40, and a control unit 50. The boost converter 20 boosts the voltage of the battery in the vehicle 100. The drive device 30 drives the traction motor 1 of the vehicle 100 with power from the boost converter 20. The AC / DC converter 40 converts a current generated by a motor generator 2 mounted on the vehicle 100 into a DC current Ir. The control unit 50 controls the drive device 30 and the AC / DC converter 40. When the drive device 30 is operated in a state in which a current flows from the drive device 30 to the reactor 21, the control unit 50 can execute a shift operation to shift the resonance frequency fr of a circuit including the reactor 21 and the capacitor 22. The shift operation shifts the resonance frequency fr by operating the AC / DC converter 40 to flow the DC current Ir to the reactor.

[0071] With this configuration, it is possible to suppress resonance of the boost converter 20 while using regenerative braking.

[0072] The boost converter 20 has upper and lower arm switching elements. A first end of the reactor 21 is connected to the battery 120, and a second end of the reactor 21 is connected to a connection point between the upper and lower arms. A smoothing capacitor 22 is connected to the upper arm. When an abnormality occurs in the boost converter 20, the control unit 50 may control the upper arm to be always on while keeping the lower arm in the off state, thereby allowing a current to flow from the drive device 30 to the reactor 21.

[0073] The control unit 50 may determine whether the vehicle speed V of the vehicle 100 is within a predetermined range, and may execute a shift operation if the vehicle speed V is within the predetermined range. This predetermined range includes, for example, a vehicle speed range corresponding to a frequency band (e.g., between f1 and f2) in which the LC circuit in the boost converter 20 resonates.

[0074] As a result, when a condition for resonating at least the LC circuit of the boost converter 20 is satisfied, the control unit 50 can suppress the resonance by executing the shift operation. When a condition for resonating the LC circuit of the boost converter 20 is satisfied, for example, when a condition for the gain G to exceed 0 [dB] is satisfied.

[0075] The shift operation may shift the resonance frequency fr to the higher frequency side by operating the AC / DC converter 40 to pass a DC current through the reactor 21. This makes it possible to lower the gain peak and reduce resonance.

[0076] The resonant frequency fr' after the shift operation does not have to be included in the resonant band of the LC circuit before the shift operation is performed. This significantly reduces resonance because the resonant frequency fr' does not fall within the resonant range.

[0077] The boost converter 20 may be a boost chopper circuit of a single chopper type. The boost converter 20 may be of a magnetically coupled interleaved type, but resonance of the boost converter 20 is unlikely to occur due to the magnetic cancellation effect of the interleaving. If the boost converter 20 is of a single chopper type, the magnetic cancellation effect cannot be obtained. Therefore, if the boost converter 20 is of a single chopper type, resonance of the boost converter 20 is likely to occur. When the boost converter 20 is of a single chopper type, it is very effective to perform the shift operation of this embodiment.

[0078] The shift operation may be performed at least when the frequency of the ripple current flowing through the capacitor 22 is included in the range of a resonance band (frequency band H1) including the resonance frequency fr before the shift operation is performed. The case where the frequency of the ripple current is included in the range of the resonance band (frequency band H1) including the resonance frequency fr before the shift operation is performed includes the case where the rotation speed N is within the range from N1 to N2 and the case where the vehicle speed V is within the range from vehicle speed V1 to vehicle speed V2. In other words, when it is clear from calculation, measurement results, etc. that the rotation speed N is within the range from N1 to N2, it can be determined that the frequency of the ripple current is included in the range of the resonance band (frequency band H1) including the resonance frequency fr before the shift operation is performed. When it is clear from calculation, measurement results, etc. that the vehicle speed V is within the range from V1 to V2, it can be determined that the frequency of the ripple current is included in the range of the resonance band (frequency band H1) including the resonance frequency fr before the shift operation is performed. When the frequency of the ripple current is included in the range of the resonant band (frequency band H1) that includes the resonant frequency fr before the shift operation is performed, the frequency of the ripple current may be determined by directly measuring it, or it may be determined indirectly without being measured directly.

[0079] The control unit 50 may not execute the process of determining whether or not the vehicle is in a fail-safe operation in Fig. 5. For example, the control unit 50 may determine whether or not an abnormality has occurred in the boost converter 20 or in the sensor, and execute a fail-safe operation to keep the upper arm in a constantly on state when an abnormality has occurred. Then, the control unit 50 may execute step S102 when the fail-safe operation has been executed.

[0080] The function of the control unit 50 in the above-described embodiment can also be expressed as follows. That is, when the drive device 30 is operated in a state where a current flows from the drive device 30 to the reactor 21, the control unit 50 can switch between a first state in which the AC / DC converter 40 is not operated and a second state in which the AC / DC converter 40 is operated to cause a DC current from the AC / DC converter 40 to flow to the reactor 21, thereby shifting the resonant frequency fr.

[0081] <Second embodiment> A motor control device 3A according to a second embodiment will be described. In the following description, parts having the same functions as those described in the first embodiment will be given the same names and symbols, and specific descriptions of the functions will be omitted.

[0082] The motor control device 3A drives the traveling motor 1 and the motor generator 2. The motor control device 3A drives the traveling motor 1 and stores regenerative power generated by regenerative braking by the traveling motor 1 in the battery 120. The motor control device 3A stores the generated power generated by the motor generator 2 in the battery 120 and supplies it to the traveling motor 1.

[0083] Fig. 7 is a diagram showing an example of a schematic configuration of a motor control device 3A according to the second embodiment. As shown in Fig. 7, the motor control device 3A includes a capacitor 10, a boost converter 20, a drive device 30, an AC / DC converter 40, a current sensor 60, a current sensor 70, and a control unit 50A.

[0084] The current sensor 60 measures a value of a current Ib flowing between the positive terminal P1 of the battery 120 and the first terminal of the reactor 21.

[0085] The current sensor 70 measures a value of a current Ix flowing between the second terminal of the reactor 21 and the connection point X.

[0086] The control unit 50A has the functions of the control unit 50. The control unit 50A can execute a fail-safe operation of controlling the upper arm switching element Q1 to a constantly on state to drive the drive device 30. The control unit 50A can execute the shift operation described in the first embodiment.

[0087] The control unit 50A is connected to each of the current sensor 60 and the current sensor 70. The control unit 50A acquires a current value Ib from the current sensor 60. The control unit 50A acquires a current value Ix from the current sensor 70. The control unit 50A controls the operation of the AC / DC converter 40 during software operation based on the current value Ib or the current value Ix. For example, the control unit 50A controls the operation of the AC / DC converter 40 during software operation so that the current value Ib or the current value Ix becomes a preset target value. For example, the control unit 50A controls the operation of the AC / DC converter 40 during software operation so that the current value Ib or the current value Ix becomes a preset target value, thereby adjusting the torque or the rotation speed of the motor generator 2. This target value is set based on the resonance frequency fr' or the frequency band H2. For example, the target value is set depending on how much the resonance frequency is shifted by the shift operation.

[0088] The control unit 50A controls the operation of the AC / DC converter 40 during software operation so that the current value Ix measured by the current sensor 70 becomes the target value. However, if an abnormality occurs in the current sensor 60, the control unit 50A controls the operation of the AC / DC converter 40 during software operation so that the current value Ib measured by the current sensor 60 becomes the target value. During fail-safe operation in which the upper arm switching element Q1 is constantly controlled to the on state, the current value Ib and the current value Ix can be considered to be the same.

[0089] The operation of the control unit 50A according to the second embodiment will be described below. Fig. 8 is a flow chart of the operation of the control unit 50A according to the second embodiment.

[0090] The control unit 50A determines whether the vehicle 100 is in a fail-sale operation (step S201). If the control unit 50A determines that the vehicle 100 is in a fail-sale operation, the control unit 50A determines whether the current sensor 70 is malfunctioning (step S202). If the measurement result measured by the current sensor 70 is within a range indicating an abnormal value or if the control unit 50A has received information indicating an abnormality from the current sensor 70, the control unit 50A determines that the current sensor 70 is malfunctioning.

[0091] If the control unit 50A determines that the current sensor 70 is not malfunctioning, it receives the reactor current value Ix from the current sensor 70 (step S203). If the control unit 50A determines that the current sensor 70 is malfunctioning, it receives the battery current value Ib, which is the value of the current flowing to the battery, from the current sensor 60 (step S204).

[0092] The control unit 50A determines whether or not the control condition is satisfied (step S205). The process of step S205 is similar to the process of step S102, and therefore the description thereof will be omitted.

[0093] When the control unit 50A determines that the control condition is satisfied, it executes a shift operation to reduce the inductance of the reactor 21 (step S206). Specifically, when the current sensor 70 is not broken, the control unit 50A controls the operation of the AC / DC converter 40 so that the reactor current value Ix becomes a preset target value, thereby converting the generated current generated by the motor generator 2 into a DC current, and supplies this DC current to the reactor 21. In other words, the control unit 50A controls the operation of the AC / DC converter 40 so that the reactor current value Ix becomes the target value, thereby controlling the DC current flowing through the reactor 21.

[0094] When the current sensor 70 has failed, the control unit 50A controls the operation of the AC / DC converter 40 so that the battery current value Ib becomes the target value, thereby converting the generated current generated by the motor generator 2 into a DC current, and supplies this DC current to the reactor 21. In other words, the control unit 50A controls the operation of the AC / DC converter 40 so that the battery current value Ib becomes the target value, thereby controlling the DC current flowing through the reactor 21.

[0095] When the control unit 50A determines that the control condition is not satisfied, the control unit 50A does not execute the shift operation. That is, the control unit 50A maintains the initial inductance of the reactor 21 by not executing the shift operation (step S207).

[0096] As described above, the motor control device 3A according to the second embodiment includes the boost converter 20, one or more drive devices 30, one or more AC / DC converters 40, and a control unit 50A. When the drive device 30 is operated in a state in which a current flows from the drive device 30 to the reactor 21, the control unit 50A can execute a shift operation to shift the resonance frequency fr of a circuit including the reactor 21 and the capacitor 22. During the shift operation, the control unit 50A controls the AC / DC converter 40 based on the reactor current value Ix or the battery current value Ib.

[0097] With this configuration, the motor control device 3A of the second embodiment not only achieves the same effects as the first embodiment, but also can control the DC current Ir flowing through the reactor 21 more accurately.

[0098] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and designs that do not deviate from the gist of the present invention are also included.

[0099] The control unit 50 according to the first embodiment can shift the resonance frequency fr if it can pass a direct current from the AC / DC converter 40 to the reactor 21. Therefore, there is no particular limitation on the value of the direct current. For example, the control unit 50 may operate the AC / DC converter 40 based on the following formula (1).

[0100] Power of battery 120 = Output of driving motor 1 + Loss ... (1)

[0101] As an example, if the battery output voltage VBAT is 200 [V], the traction motor 1 is operating at 3000 [rpm] and 30 [Nm], and the motor generator 2 is not operating, then according to equation (1), the current flowing through the reactor 21 will be approximately +50 [A].

[0102] 200[V]×50[A]=3000[rpm]×30[Nm]×(2π / 60)+Loss …(2)

[0103] For example, when the control unit 50 aims for a reactor current target value of -200 [A], it is sufficient for the control unit 50 to operate the motor generator 2 at approximately -50 kW.

[0104] In this way, when a target value of the DC current Ir to be flowed through the reactor 21 is set, the control unit 50 may control the operation of the AC / DC converter 40 based on the power of the battery 120 and the power of the traction motor 1.

[0105] The term "unit" in the specification means a unit that processes at least one function or operation, which may be embodied as hardware or software, or a combination of hardware and software. [Explanation of symbols]

[0106] 1. Driving motor 2 Motor generator 3 Motor control device 20 Boost Converter 21 Reactor 22 Capacitor (smoothing capacitor) 30 Drive unit 40 AC / DC converter 100 vehicles 120 Battery Q1, Q2 switching elements

Claims

1. a boost converter having a reactor and a smoothing capacitor and configured to boost a voltage of a battery in a vehicle; at least one drive device that drives a traction motor of the vehicle with electric power from the boost converter; at least one AC / DC converter that converts a current generated by a motor generator mounted on the vehicle into a DC current; A control unit that controls the drive device and the AC / DC converter; Equipped with the control unit is capable of executing a shift operation to shift a resonant frequency of a circuit including the reactor and the smoothing capacitor when the drive device is operated in a state in which a current flows from the drive device to the reactor, the shift operation shifts the resonant frequency by operating the AC / DC converter to cause the DC current to flow through the reactor; the boost converter has upper arm and lower arm switching elements, the reactor has a first end connected to the battery and a second end connected to a connection point between the upper arm and the lower arm; the smoothing capacitor is connected to the upper arm, When an abnormality occurs in the boost converter, the control unit controls the lower arm to be kept in an off state and the upper arm to be always in an on state, thereby causing a current to flow from the drive device to the reactor. Motor control device.

2. The shift operation shifts the resonant frequency to a higher frequency by operating the AC / DC converter to cause the DC current to flow through the reactor. The motor control device according to claim 1 .

3. The control unit determines whether or not a vehicle speed of the vehicle is within a predetermined range, and executes the shift operation when the vehicle speed is within the predetermined range. The predetermined range includes a vehicle speed range corresponding to a frequency band in which the circuit resonates. The motor control device according to claim 1 or 2.

4. The resonant frequency after the shift operation is performed is not included in the frequency band before the shift operation is performed. The motor control device according to claim 3.

5. The control unit controls the AC / DC converter based on a current value flowing through the reactor or a current value flowing through the battery during the shift operation. The motor control device according to any one of claims 1 to 4.

6. The boost converter is a single chopper type boost chopper circuit. The motor control device according to any one of claims 1 to 5.

7. The shift operation is performed when a frequency of a ripple current flowing through the smoothing capacitor by at least the traction motor is included in a range of a predetermined frequency band including the resonant frequency before the shift operation is performed. The motor control device according to claim 1 or 2.

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