Motor control device, electric vehicle, and motor control method

Abstract

A control device for a motor (200) cooled by an insulating refrigerant (300) circulated by a pump (310) comprises: a current command calculation unit (10) for calculating a current command based on a torque command for the motor, a DC voltage applied from a power supply to a power conversion circuit (100), and a rotor position of the motor; and a limiting unit for limiting a maximum value of a voltage applied to the motor (200) based on the calculated current command, the DC voltage, and a flow rate and temperature of the insulating refrigerant.

Description

Technical Field

[0001] The present invention relates to a control device for a motor, an electric vehicle and a control method for a motor. Background Art

[0002] In order to ensure insulation resistance and improve cooling performance by circulating the refrigerant, a motor cooled by insulating refrigerant liquid is required. Therefore, a technology for controlling the flow rate of the refrigerant based on the temperature of the insulating refrigerant has been proposed.

[0003] As a background technology of the present invention, the following patent document 1 is known. Patent document 1 describes an electrical device, which increases the flow rate of the insulating medium circulating between the electrical device and the cooling device from a steady-state flow rate to a flow rate that does not exceed the upper limit flow rate of the no-discharge region corresponding to the insulating medium temperature detected by the temperature detection unit when the insulating medium temperature detected by the temperature detection unit exceeds a predetermined value. In this way, it is possible to ensure both insulation resistance and improve cooling performance, and to increase the maximum output of the electrical device.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2006-32651 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] In Patent Document 1, when the temperature of the insulating refrigerant changes suddenly, the control of the refrigerant flow rate is delayed. This reduces the insulation resistance of the electrical equipment and may also reduce the output. Therefore, it is a problem to ensure the insulation resistance of the electrical equipment even when the temperature of the insulating refrigerant changes suddenly.

[0009] Technical means of solving problems

[0010] A control device for an electric motor cooled by an insulating refrigerant circulated by a pump comprises: a current command calculation unit that calculates a current command based on a torque command for the electric motor, a DC voltage applied from a power supply to a power conversion circuit, and a rotor position of the electric motor; and a limiting unit that limits a maximum value of a voltage applied to the electric motor based on the calculated current command, the DC voltage, and a flow rate and temperature of the insulating refrigerant.

[0011] Effects of the Invention

[0012] According to the present invention, the electric motor can ensure insulation resistance corresponding to a rapid change in temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is the overall configuration of a motor and a motor control device according to an embodiment of the present invention.

[0014] Figure 2 This is a control block diagram of the electric motor control device according to the first embodiment of the present invention.

[0015] Figure 3 This is a process flow chart of the restriction unit included in the electric motor control device according to the first embodiment of the present invention.

[0016] Figure 4 This is a voltage waveform pattern applied to the motor during switching according to the first embodiment of the present invention.

[0017] Figure 5 This is a process flow chart of a restriction unit included in the electric motor control device according to the second embodiment of the present invention.

[0018] Figure 6 This is a process flow chart of a restriction unit included in the electric motor control device according to the third embodiment of the present invention.

[0019] Figure 7 This is a reference diagram of a waveform of a gate voltage applied to a switching element according to the third embodiment of the present invention.

[0020] Figure 8 This is a diagram showing an electric vehicle to which the control device for the electric motor according to the present invention is applied. DETAILED DESCRIPTION

[0021] (Structure of Motor Control Device and First Embodiment)

[0022] Figure 1 1 is a diagram showing the overall configuration of a control device associated with a motor and inverter control device 2 (hereinafter simply referred to as a control device 2 ) according to an embodiment of the present invention.

[0023] like Figure 1 As shown, the overall structure of the motor and the motor control device includes: an electric system control device 1 (hereinafter referred to as control device 1), a control device 2, a pump control device 3 (hereinafter referred to as control device 3), an inverter 100, a motor 200, a position sensor 210, a current sensor 220, a voltage sensor 230, an insulating refrigerant 300, a pump 310, a refrigerant flow sensor 320 and a refrigerant temperature sensor 330.

[0024] The control device 1 outputs a torque command to the motor 200 based on a command input from a higher-level control device (not shown). The torque command is input to the control device 2 .

[0025] The control device 2 performs PWM control of the inverter 100 through a switching signal based on the torque command input from the control device 1, the three-phase AC current detected by the current sensor 220, the rotor position of the motor 200 detected by the position sensor 210, and the input voltage detected by the voltage sensor 230. In addition, the details of the inside of the control device 2 will be described later.

[0026] The control device 3 outputs a refrigerant flow rate instruction for controlling the flow rate of the insulating refrigerant 300 to the pump 310 based on the refrigerant flow rate input from the refrigerant flow rate sensor 320 and the refrigerant temperature input from the refrigerant temperature sensor 330 so that the motor 200 does not malfunction due to overtemperature.

[0027] The inverter 100 as a power conversion circuit is composed of switching elements 110a to 110f. The switching element 110a is arranged at the U-phase upper arm, the switching element 110b is arranged at the U-phase lower arm, the switching element 110c is arranged at the V-phase upper arm, the switching element 110d is arranged at the V-phase lower arm, the switching element 110e is arranged at the W-phase upper arm, and the switching element 110f is arranged at the W-phase lower arm.

[0028] The switching elements 110 a to 110 f are formed by combining a metal oxide field effect transistor (MOSFET), an insulated gate bipolar transistor (IGBT), or the like with a diode.

[0029] In addition, the switching elements 110a to 110f are respectively turned on or off based on the switching signal generated by the control device 2. Thus, the switching elements 110a to 110f convert the DC voltage applied from the external DC power supply into an AC voltage. Here, the converted AC voltage is applied to the stator of the motor 200, so that the three-phase coils provided on the stator generate AC currents respectively. The three-phase AC currents cause the motor 200 to generate a rotating magnetic field, thereby rotating the rotor of the motor 200. In addition, the temperature of the switching elements 110a to 110f is detected by a detection unit not shown in the figure, and is fed back to the control device 2.

[0030] The position sensor 210 detects the position of the rotor of the motor 200. The rotor position detected here is output to the control device 2.

[0031] The current sensor 220 detects the three-phase AC current flowing through the motor 200. The three-phase AC current detected here is output to the control device 2.

[0032] The voltage sensor 230 detects a DC voltage (hereinafter referred to as input voltage) applied to the inverter 100 from an external DC power source such as a battery, and outputs the detected input voltage to the control device 2 .

[0033] The insulating refrigerant 300 is filled in the motor 200 and circulated by the pump 310. The insulating refrigerant 300 circulates between the motor 200 and the pump 310 through a cooling structure (not shown) to cool the motor 200. The insulating refrigerant 300 uses a liquid having electrical insulation properties such as transformer mineral oil or gear oil.

[0034] The pump 310 circulates the insulating refrigerant 300 and controls the flow rate based on the refrigerant flow rate command input from the pump control device 3 .

[0035] The refrigerant flow rate sensor 320 detects the flow rate of the insulating refrigerant 300. The detected refrigerant flow rate is input to the control device 2 and the control device 3.

[0036] The refrigerant temperature sensor 330 detects the temperature of the insulating refrigerant 300. The detected refrigerant temperature is input to the control device 2 and the control device 3.

[0037] Figure 2 This is a control block diagram of the electric motor control device according to the first embodiment of the present invention.

[0038] exist Figure 2 The current command operation unit 10 (hereinafter referred to as the operation unit 10), the limiting unit 20, the current control unit 30, the PWM signal generation unit 40 and the speed conversion unit 50 in the block diagram are arranged inside the control device 2 which is the main structure of the present invention.

[0039] The calculation unit 10 calculates a pre-limit current command based on the torque command input from the control device 1 , the angular velocity and rotor position fed back from the motor 200 via the speed conversion unit 50 , the switching element temperature fed back from the inverter 100 , and the input voltage detected by the voltage sensor 230 .

[0040] The calculation of the pre-limitation current command output from the operation unit 10 to the limiter 20 uses a known calculation technique such as maximum torque current control for minimizing the output current and maximum efficiency control for minimizing the power loss.

[0041] In addition, in order to prevent the switching elements 110a to 110f of the inverter 100 from being damaged due to over-temperature, the pre-limit current command is controlled based on the switching element temperature. However, depending on the use conditions of the inverter 100, the pre-limit current command may be calculated without considering the influence of the switching element temperature. In this case, it is not necessary to feed back the switching element temperature from the inverter 100 to the calculation unit 10.

[0042] The limiting unit 20 calculates the post-limiting current command based on the pre-limiting current command input from the calculation unit 10, the refrigerant flow rate and refrigerant temperature fed back from the sensors 320 and 330, and the input voltage fed back from the voltage sensor 230. Figure 3 Provide explanation.

[0043] The current control unit 30 outputs a voltage command to the PWM signal generation unit 40 based on a known technique such as proportional control and integral control based on a predetermined control gain according to the limited current command input from the limiter 20 and the three-phase AC current fed back from the current sensor 220 .

[0044] The PWM signal generation unit 40 generates a switching signal for turning on or off the switching elements 110a to 110f based on the input voltage command. When generating the switching signal, a triangle wave carrier comparison method or a space vector modulation method, which are well-known techniques, is used.

[0045] The data of the rotor position of the motor 200 detected by the position sensor 210 is fed back to the speed conversion unit 50. The speed conversion unit 50 outputs the angular velocity to the current command calculation unit 10 based on the data of the rotor position of the motor 200.

[0046] Figure 3 This is a flowchart of the process of the restriction unit 20 .

[0047] In step S1, the insulation withstand voltage is calculated based on the temperature and flow rate of the insulating refrigerant 300. The insulation withstand voltage of the motor 200 changes according to the temperature and flow rate of the insulating refrigerant 300. However, since it is affected by the flow electrification phenomenon, it is also necessary to measure the leakage current in order to evaluate the influence. The leakage current changes according to the temperature and flow rate of the insulating refrigerant 300, just like the insulation withstand voltage. Therefore, the relationship data of the insulation withstand voltage and the leakage current that differ according to the temperature and flow rate of the insulating refrigerant 300 is stored in the limiting unit 20 in advance, and the correct insulation withstand voltage corresponding to the situation is calculated based on the data.

[0048] In step S2, the maximum value of the voltage applied to the motor 200 is calculated. The maximum value of the voltage occurs when the switching elements 110a to 110f are turned on or off. The magnitude of the voltage is related to the current when it is turned on or off, that is, the magnitude of the three-phase AC current. In addition, the amplitude of the voltage applied to the motor 200 changes as the input voltage changes. Therefore, for example, it is necessary to pre-store the relationship between the maximum value of the three-phase AC current and the voltage under the condition where the voltage applied to the motor 200 becomes maximum, that is, when the input voltage becomes maximum. Therefore, the relationship data between the three-phase AC current and the instantaneous maximum voltage that differs according to the input voltage is pre-stored in the limiting unit 20, and the correct maximum value of the voltage corresponding to the situation is calculated based on the data and the pre-limitation current instruction input from the operation unit 10.

[0049] In step S3, the insulation withstand voltage calculated in step S1 is compared with the maximum value of the voltage calculated in step S2 to determine whether the maximum value of the voltage is less than the insulation withstand voltage. At this time, considering that the insulation withstand voltage calculated in step S1 and the maximum value of the voltage calculated in step S2 each contain errors, it is preferred to determine whether the sum of the maximum value of the voltage and the insulation withstand voltage tolerance is less than the insulation withstand voltage.

[0050] The insulation withstand voltage tolerance is a value additionally set to the calculated insulation withstand voltage in order to prevent the maximum voltage from exceeding the insulation withstand voltage. Specifically, the insulation withstand voltage tolerance is set when the insulation withstand voltage calculation error caused by the detection error of the temperature and flow rate of the insulating refrigerant 300, the insulation withstand voltage reduction caused by the aging degradation of the insulating refrigerant 300, the increase or decrease of the maximum voltage value accompanying the change of the input voltage, the increase or decrease of the maximum voltage value caused by the change of the switching element temperature, etc. occur in combination. If there are many unconsidered variable factors when calculating the insulation withstand voltage and the maximum voltage, and the calculation error is large, the insulation withstand voltage tolerance value needs to be set larger.

[0051] In step S3, if the maximum voltage is determined to be less than the insulation withstand voltage, the pre-limit current command is output without limiting, and the flowchart ends. On the other hand, if the maximum voltage is determined to be greater than the insulation withstand voltage, the process moves to step S4.

[0052] In step S4, the value of the three-phase AC current at which the maximum voltage becomes smaller than the insulation withstand voltage calculated in step S1 is calculated as the output current after limitation in the relationship data between the three-phase AC current and the maximum voltage used when calculating the maximum voltage in step S2. Then, the calculated limited current command is output to the current control unit 30, and the flowchart ends. Thus, the three-phase AC current output from the inverter 100 to the motor 200 is limited, and the maximum value of the voltage applied from the inverter 100 to the motor 200 is limited. At this time, it is preferred that the sum of the maximum voltage and the insulation withstand voltage tolerance is less than the insulation withstand voltage according to the error.

[0053] Figure 4 yes Figure 3 An example of a voltage waveform pattern applied to the motor during switching in steps S3 and S4 in FIG.

[0054] For example, in the case 4 where the input voltage is high and the three-phase AC current is also large, the maximum value of the voltage applied to the motor 200 during switching may exceed the insulation withstand voltage. In step S3 of the limiting unit 20, the control device 2 determines that the maximum value of the voltage is greater than the insulation withstand voltage. As a result, the control device 2 transfers to step S4 of the limiting unit 20. In step S4, the current command after limitation is calculated, such as Figure 4 As shown in Example 3, the maximum voltage is limited to be less than the insulation withstand voltage.

[0055] On the other hand, when the input voltage is low and the three-phase AC current is also low, if the three-phase AC current is limited, as in Case 1, the maximum value of the voltage applied to the motor 200 during switching is excessively limited, and the output of the inverter 100 is reduced beyond normal necessity. Figure 3 In step S2, based on the relationship between the maximum values ​​of the three-phase AC current and the voltage stored for each input voltage, the maximum value of the voltage suitable for the situation is calculated to cope with it.

[0056] According to the first embodiment of the present invention described above, the following effects are achieved.

[0057] (1) A control device 2 for a motor 200 cooled by an insulating refrigerant 300 circulated by a pump 310 includes: a current command calculation unit 10 that calculates a current command based on a torque command for the motor 200, a DC voltage applied from a power supply to an inverter 100, and a rotor position of the motor 200; and a limiting unit 20 that limits a maximum value of a voltage applied to the motor 200 based on the calculated current command, the DC voltage, and the flow rate and temperature of the insulating refrigerant 300. In this way, the motor 200 can ensure insulation resistance corresponding to a sudden change in temperature.

[0058] (2) Limiting unit 20 limits the maximum value of the voltage applied to motor 200 by limiting the three-phase AC current output from inverter 100 to motor 200. Thus, the maximum value of the voltage applied to motor 200 can be limited in the control of the three-phase AC current by control device 2.

[0059] (3) The limiting unit 20 calculates the insulation withstand voltage of the motor 200 based on the flow rate and temperature of the insulating refrigerant 300 (step S1), and limits the maximum value of the voltage applied to the motor 200 based on the calculated insulation withstand voltage (steps S2 to S4). In this way, the maximum value of the voltage applied to the motor 200 can be appropriately limited according to the insulation withstand voltage.

[0060] (4) The limiting unit 20 calculates the maximum value of the voltage applied to the motor 200 based on the current command and the DC voltage (step S2), and limits the maximum value of the voltage applied to the motor 200 so that the calculated maximum value of the voltage becomes smaller than the insulation withstand voltage (steps S3 and S4). In this way, the maximum value of the voltage can be reliably kept below the insulation withstand voltage, thereby ensuring the insulation withstand capacity of the motor 200.

[0061] (Second embodiment)

[0062] Figure 5 This is a flowchart of the process of the limiter 20 for limiting the maximum value of the voltage based on the switching element temperature of the inverter 100 according to the second embodiment of the present invention.

[0063] The maximum value of the voltage applied to the motor 200 is generated when the switching elements 110 a to 110 f are turned on or off, and the magnitude of the voltage is related to the temperature of the switching element when it is turned on or off.

[0064] In step S1, Figure 3 Similarly, in step S1 , the insulation withstand voltage is calculated based on the temperature and flow rate of the insulation refrigerant 300 .

[0065] In the present embodiment, the data of the relationship between the maximum value of the three-phase AC current and the voltage applied from the inverter 100 to the motor 200 is pre-stored for each switching element temperature in the limiting unit 20. In step S2, the data corresponding to the switching element temperature fed back from the inverter 100 to the limiting unit 20 is selected from the data of the relationship between the maximum value of the three-phase AC current and the voltage pre-stored for each switching element temperature. Based on the data selected in this way, a more accurate maximum value of the voltage can be calculated from the fed-back input voltage and the pre-limitation current command input from the calculation unit 10.

[0066] In step S3, Figure 3Similarly, in step S3, if it is determined that the maximum value of the voltage is less than the insulation withstand voltage, the pre-limit current command is output without limitation, and the flowchart ends. On the other hand, if it is determined that the maximum value of the voltage is greater than the insulation withstand voltage, the flow goes to step S4.

[0067] In step S4, Figure 3 Similarly, in step S4, based on the relationship between the maximum values ​​of the three-phase AC current and the voltage selected in step S2, the value of the three-phase AC current is calculated as the output current after limitation so that the maximum value of the voltage becomes smaller than the insulation withstand voltage calculated in step S1. Then, the calculated limited current command is output to the current control unit 30, and the flowchart ends. At this time, it is preferred that the sum of the maximum value of the voltage and the insulation withstand voltage tolerance is smaller than the insulation withstand voltage according to the error.

[0068] According to the second embodiment of the present invention described above, the following effects are achieved.

[0069] (5) The limiting unit 20 calculates the maximum value of the voltage applied to the motor 200 based on the current command, the DC voltage, and the temperature of the switching elements 110a to 110f of the inverter 100 (step S2). In this way, the maximum value of the voltage can be calculated based on information other than the input voltage, and the motor 200 can ensure the insulation resistance corresponding to the rapid change of temperature. In addition, the insulation withstand voltage tolerance can be reduced, and excessive restriction of the output three-phase AC current can be suppressed.

[0070] (Third embodiment)

[0071] Figure 6 This is a flowchart of the processing of the limiter 20 which limits the maximum value of the voltage based on the gate voltage according to the third embodiment of the present invention.

[0072] The maximum value of the voltage applied to the motor 200 occurs when the switching elements 110 a to 110 f are turned on or off, and the magnitude thereof is related to the amplitude of the gate voltage that drives the switching elements to turn on or off.

[0073] In step S1, Figure 3 , 5 Similarly, in step S1 , the insulation withstand voltage is calculated based on the temperature and flow rate of the insulation refrigerant 300 .

[0074] In the present embodiment, the relationship data between the maximum value of the three-phase alternating current and the voltage applied from the inverter 100 to the motor 200 is pre-stored in the limiting unit 20 for each gate voltage. In addition, the gate voltage is controlled by a control unit (not shown) using a known technique so that it is not excessively applied. As a result, the gate voltage of the switching elements 110a to 110f that drive the inverter 100 changes. In step S2, the data corresponding to the current gate voltage is selected from the data of the relationship between the maximum value of the three-phase alternating current and the voltage pre-stored for each gate voltage. Based on the data selected in this way, the maximum value of the correct voltage corresponding to the situation is calculated based on the fed-back input voltage and the pre-limitation current instruction input from the operation unit 10.

[0075] In step S3, Figure 3 , 5 Similarly, in step S3, if it is determined that the maximum value of the voltage is less than the insulation withstand voltage, the pre-limit current command is output without limitation, and the flowchart ends. On the other hand, if it is determined that the maximum value of the voltage is greater than the insulation withstand voltage, the flow goes to step S4.

[0076] In step S4, the maximum value of the calculated voltage is smaller than the gate voltage such as the dielectric withstand voltage. If the amplitude of the gate voltage is reduced, the speed at which the gate voltage rises or falls will be reduced accordingly. As a result, since the speed at which the switching elements 110a to 110f are turned on or off is reduced, the maximum value of the voltage can be limited by reducing the amplitude of the gate voltage.

[0077] In step S5, the relationship corresponding to the gate voltage calculated in step S4 is selected from the relationships between the three-phase alternating current and the maximum voltage for each gate voltage pre-stored in the limiting unit 20. Then, based on the selected relationship between the three-phase alternating current and the maximum voltage, the value of the three-phase alternating current is calculated as the output current after limitation so that the maximum voltage becomes smaller than the insulation withstand voltage calculated in step S1. Then, the calculated current command after limitation is output to the current control unit 30, and the flowchart ends.

[0078] Figure 7 This is a reference diagram of the waveform of the gate voltage applied to the switching element according to the third embodiment.

[0079] If you make Figure 7 The gate voltage at which the switching elements 110a to 110f are turned on or off is reduced from ±15V to ±12V, for example, and the amplitude is reduced by 6V. If the gate voltage amplitude is reduced, the maximum value of the associated voltage is also reduced, and the insulation withstand voltage tolerance is also reduced.

[0080] According to the third embodiment of the present invention described above, the following effects are achieved.

[0081] (6) The limiting unit 20 calculates the maximum value of the voltage applied to the motor 200 based on the current command, the DC voltage, and the gate voltage of the switching elements 110a to 110f driving the inverter 100 (step S2). In this way, the maximum value of the voltage can be calculated based on information other than the input voltage, and the motor 200 can ensure the insulation resistance corresponding to the rapid change of temperature. In addition, the insulation withstand voltage tolerance can be reduced, and excessive restriction of the output three-phase AC current can be prevented.

[0082] (Electric Vehicles)

[0083] Figure 8 1 is a diagram showing an electric vehicle 600 to which the control device 2 of the present invention is applied. The electric vehicle 600 has a power train using the motor 200 as a motor / generator.

[0084] A front wheel axle 601 is rotatably supported at the front of the electric vehicle 600, and front wheels 602 and 603 are provided at both ends of the front wheel axle 601. A rear wheel axle 604 is rotatably supported at the rear of the electric vehicle 600, and rear wheels 605 and 606 are provided at both ends of the rear wheel axle 604.

[0085] A differential gear 611 as a power distribution mechanism is provided in the center of the front wheel axle 601, and the rotational driving force transmitted from the engine 610 via the transmission 612 is distributed to the left and right front wheel axles 601. The engine 610 and the motor 200 are mechanically connected via a belt, and the belt is stretched between a pulley provided on the crankshaft of the engine 610 and a pulley provided on the rotating shaft of the motor 200.

[0086] Thus, the rotational driving force of the motor 200 can be transmitted to the engine 610, and the rotational driving force of the engine 610 can be transmitted to the motor 200. Under the control of the control device 2, the motor 200 supplies the three-phase AC power output from the inverter 100 to the stator coil of the stator, thereby rotating the rotor and generating a rotational driving force corresponding to the three-phase AC power.

[0087] That is, the motor 200 is controlled by the control device 2 to operate as an electric motor, and on the other hand, the rotor rotates by receiving the rotational driving force of the engine 610, and operates as a generator that generates three-phase alternating current.

[0088] The inverter 100 is an electric power conversion device that converts DC power provided by a high voltage (42V or 300V) power source, i.e., a high voltage battery 622, into three-phase AC power, and controls the three-phase AC current flowing through the stator coil of the motor 200 based on the operating command value and the magnetic pole position of the rotor.

[0089] The three-phase AC power generated by the motor 200 is converted into DC power by the inverter 100 to charge the high-voltage battery 622. The high-voltage battery 622 is electrically connected to the low-voltage battery 623 via the DC / DC converter 624. The low-voltage battery 623 constitutes the low-voltage (14V) power supply of the electric vehicle 600, and is used to power the starter 625 for initial start (cold start) of the engine 610, the radio, the lights, etc.

[0090] When the electric vehicle 600 is stopped (idling stop mode) such as waiting for a traffic light, the engine 610 is stopped. When the engine 610 is restarted (hot start) when the vehicle is restarted, the inverter 100 drives the motor 200 to restart the engine 610.

[0091] In addition, in the idle stop mode, when the charge amount of the high-voltage battery 622 is insufficient or the engine 610 is not sufficiently heated, the engine 610 is not stopped but driven continuously. In addition, in the idle stop mode, it is necessary to ensure the driving source of auxiliary machines such as the compressor of the air conditioner that use the engine 610 as a driving source. In this case, the auxiliary machines are driven by the driving motor 200.

[0092] In the acceleration mode or the high load operation mode, the motor 200 is also driven to assist the driving of the engine 610. On the contrary, in the charging mode in which the high voltage battery 622 needs to be charged, the motor 200 generates electricity through the engine 610 to charge the high voltage battery 622. That is, the motor 200 performs regenerative operation when the electric vehicle 600 is braked or decelerated.

[0093] The electric vehicle 600 includes: a control device 2 that issues a command to limit the three-phase AC current applied to the motor 200 based on the temperature and flow rate of the insulating refrigerant; an inverter 100 that converts a DC voltage into an AC voltage to drive the motor 200 by means of a limited PWM pulse output from the control device 2; and a DC / DC converter 624 that boosts the DC voltage. Thus, the insulating refrigerant 300 can be stably controlled even during vehicle driving.

[0094] Each embodiment and various modifications described above are only examples, and the present invention is not limited to these contents as long as the features of the invention are not impaired. In addition, various embodiments and modifications are described above, but the present invention is not limited to these contents. Other modes that can be thought of within the scope of the technical thought of the present invention are also included in the scope of the present invention.

[0095] Explanation of symbols

[0096] 1 Electric system control device

[0097] 2 Inverter control device

[0098] 3 Pump Controls

[0099] 10 Current command calculation unit

[0100] 20 Restriction

[0101] 30 Current control unit

[0102] 40 PWM signal generation unit

[0103] 50 Speed ​​conversion unit

[0104] 100 Inverter

[0105] 110a U phase upper arm switching element

[0106] 110b U-phase lower arm switching element

[0107] 110c V phase upper arm switching element

[0108] 110d V-phase lower arm switch element

[0109] 110e W phase upper arm switching element

[0110] 110f W phase lower arm switching element

[0111] 200 Motor

[0112] 210 Position sensor

[0113] 220 Current sensor

[0114] 230 Voltage sensor

[0115] 300 Insulation Refrigerant

[0116] 310 Pump

[0117] 320 Refrigerant Flow Sensor

[0118] 330 Refrigerant temperature sensor

[0119] 600 Electric vehicles.

Claims

1. A control device for a motor cooled by an insulating refrigerant circulated by a pump, The control device is characterized by comprising: a current command calculation unit that calculates a current command based on a torque command to the motor, a DC voltage applied from a power supply to a power conversion circuit, and a rotor position of the motor; and a limiting unit that limits a maximum value of a voltage applied to the motor based on the calculated current command, the DC voltage, and the flow rate and temperature of the insulating refrigerant, The limiting unit calculates a dielectric withstand voltage of the motor based on a flow rate and a temperature of the insulating refrigerant, and limits a maximum value of the voltage based on the calculated dielectric withstand voltage, wherein the calculated dielectric withstand voltage decreases as the flow rate of the insulating refrigerant increases.

2. The control device according to claim 1, characterized in that: The limiting unit limits the maximum value of the voltage by limiting the three-phase alternating current output from the power conversion circuit to the motor.

3. The control device according to claim 1, characterized in that: The limiting unit calculates a maximum value of the voltage based on the current command and the DC voltage, and limits the maximum value of the voltage so that the maximum value of the voltage becomes smaller than the insulation withstand voltage.

4. The control device according to claim 3, characterized in that: The limiting unit calculates a maximum value of the voltage based on the current command, the DC voltage, and a temperature of a switching element of the power conversion circuit.

5. The control device according to claim 3, characterized in that: The limiting unit calculates a maximum value of the voltage based on the current command, the DC voltage, and a gate voltage of a switching element driving the power conversion circuit.

6. An electric vehicle, characterized in that: A control device according to any one of claims 1 to 5 is provided.

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