Controller of electric vehicle

Abstract

To provide a controller of an electric vehicle which favorably suppresses, when insulation oil is not normally supplied from an electric oil pump to an electric motor, insulation failure in the electric motor from occurring.SOLUTION: A controller of an electric vehicle comprises: an electric motor; a battery which exchanges electric power between the battery and the electric motor; and an electric oil pump which supplies the electric motor with insulation oil. When the insulation oil is not normally supplied from the electric oil pump to the electric motor, allowable charge power of the battery is limited to be smaller relative to a case that the insulation oil is normally supplied from the electric oil pump to the electric motor.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a control device for an electric vehicle including an electric motor and a battery that exchanges power with the electric motor.

Background Art

[0002] Conventionally, a vehicle including a motor, an inverter that drives the motor, a battery, a boost converter that is connected to a battery voltage system to which the battery is connected and a drive voltage system to which the inverter is connected and that adjusts the voltage of the drive voltage system, and a control device has been known (see, for example, Patent Document 1). The control device of this vehicle controls the boost converter so that the voltage of the drive voltage system is adjusted within a range not exceeding an allowable upper limit voltage. Further, the control device sets the allowable upper limit voltage so that it tends to be higher as the degree of insulation deterioration of the motor is smaller.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in order to improve the running performance and energy efficiency (so-called electricity cost) of an electric vehicle, when increasing the voltage of the battery or speeding up the switching of the inverter, it is necessary to increase the withstand voltage of the insulation of the electric motor of the electric vehicle. And in order to increase the withstand voltage of the insulation of the electric motor, it is conceivable to supply insulating oil from an electric oil pump to the electric motor during running of the electric vehicle. However, in this case, when the oil cannot be normally supplied from the electric oil pump to the electric motor, the withstand voltage of the insulation may decrease, leading to insulation failure.

[0005] Therefore, the main object of the present disclosure is to favorably suppress the occurrence of insulation failure in the electric motor even when the electric oil pump cannot normally supply the insulating oil to the electric motor.

Means for Solving the Problems

[0006] A control device for an electric vehicle according to the present disclosure is a control device for an electric vehicle including an electric motor, a battery that exchanges power with the electric motor, and an electric oil pump that supplies insulating oil to the electric motor, and when the oil cannot be normally supplied from the electric oil pump to the electric motor, the allowable charging power of the battery is limited to be smaller than when the oil is normally supplied from the electric oil pump to the electric motor.

[0007] The control device for an electric vehicle according to the present disclosure, when the insulating oil cannot be normally supplied from the electric oil pump to the electric motor, limits the allowable charging power of the battery to be smaller than when the oil is normally supplied from the electric oil pump to the electric motor. Thereby, the voltage applied to the electric motor that exchanges power with the battery can be limited within a range where insulation is ensured in the electric motor. As a result, according to the control device for an electric vehicle of the present disclosure, even when the insulating oil cannot be normally supplied from the electric oil pump to the electric motor, it is possible to favorably suppress the occurrence of insulation failure in the electric motor.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0009] Next, embodiments for implementing the invention of the present disclosure will be described with reference to the drawings.

[0010] FIG. 1 is a schematic configuration diagram showing an electric vehicle 1 including the control device of the present disclosure. As shown in the figure, the electric vehicle 1 is a battery electric vehicle (BEV) including a motor generator (electric motor) MG that drives a pair of drive wheels DW, a battery (power storage device) 2, an inverter 3, and an electronic control unit (hereinafter referred to as "ECU") 10 which is the control device of the present disclosure. However, the electric vehicle 1 may be a plug-in hybrid vehicle (PHEV) including an internal combustion engine (engine) in addition to the battery 2, the motor generator MG, etc.

[0011] The motor generator MG is a synchronous generator motor (three-phase alternating current motor) including a stator S and a rotor R, and exchanges electric power with the battery 2 via the inverter 3. The battery 2 is, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery having a rated output voltage of about 800V. The inverter 3 drives the motor generator MG and includes, for example, six transistors and six diodes connected in parallel in the reverse direction to each transistor. The inverter 3 is connected to the battery 2 via a system main relay SMR.

[0012] Furthermore, as shown in FIG. 2, the electric vehicle 1 includes a charging relay DCR, a charging inlet CI, and a charging electronic control unit (hereinafter referred to as "charging ECU") 15. The charging relay DCR is connected to the neutral point NP of the motor generator MG via a power line, and is connected to the negative power line between the system main relay SMR and the inverter 3 via the power line. The charging inlet CI is disposed inside a charging lid (not shown) of the electric vehicle 1 and is connected to the charging relay DCR via a power line. Thereby, when both the system main relay SMR and the charging relay DCR are closed, the battery 2 is electrically connected to the charging inlet CI via the motor generator MG and the inverter 3. And, a charging connector 51 of a DC external charging device 50 installed in a charging stand or the like is inserted (connected) into the charging inlet CI.

[0013] Also, as shown in FIG. 1, the rotor R of the motor generator MG is connected to a pair of drive wheels DW via a reduction mechanism 4, a differential gear 5, and a drive shaft 6. The motor generator MG, a part of the reduction mechanism 4, the differential gear 5, and each drive shaft 6 are housed in a transaxle case 7 and constitute a transaxle of the electric vehicle 1. Further, a working oil storage portion for storing the working oil (ATF) O as a lubricating and cooling medium is defined at the lower part of the transaxle case 7, and the working oil O scooped up by the gears included in the reduction mechanism 4 and the differential gear 5 is supplied to the lubricating and cooling targets such as the gears and bearings in the transaxle case 7 via an oil passage or a guide (not shown).

[0014] Furthermore, in the electric vehicle 1, a strainer 8 and an electric oil pump 9 are disposed in the transaxle case 7. The strainer 8 is fixed in the hydraulic oil reservoir such that, for example, a suction port provided at the bottom opens downward. The suction port of the electric oil pump 9 is connected to the oil outlet of the strainer 8, and an air-cooled or water-cooled oil cooler (not shown) is connected to the discharge port of the electric oil pump 9 via an oil pipe or the like (not shown). The hydraulic oil O flowing out of the oil cooler is supplied into the interior of the rotor R of the motor generator MG via an oil passage or the like (not shown), and is supplied from the interior of the rotor R to the stator S, the stator coil wound around the stator S, the coil ends of the stator coil, and the like.

[0015] And in the electric vehicle 1, the oil passages around the stator S and the like are increased so as to distribute a sufficient amount of hydraulic oil O (insulating oil) to the portions where insulation of the motor generator MG is required. Thereby, the dielectric breakdown voltage of the motor generator MG can be increased, and the increase in the high voltage of the battery 2 and the speeding up of the switching of the inverter 3 can be achieved. Further, the hydraulic oil O from the electric oil pump 9 is also supplied to bearings and the like around the motor generator MG, and the hydraulic oil O that has passed through the lubrication and cooling targets such as the motor generator MG flows down to the hydraulic oil reservoir.

[0016] The ECU 10 includes a computer having a CPU, a ROM, a RAM, an input / output interface, etc., various drive circuits, various logic ICs, etc., and controls (switching control) the inverter 3. The ECU 10 acquires the accelerator opening Acc indicating the depression amount of the accelerator pedal detected by an accelerator pedal position sensor (not shown), the vehicle speed V detected by a vehicle speed sensor (not shown), the SOC (charge rate) of the battery 2 calculated by a battery electronic control unit (hereinafter referred to as "battery ECU") 20 that manages the battery 2, the allowable charging power Win (negative value) and the allowable discharging power Wout (positive value), the atmospheric pressure Pa detected by an atmospheric pressure sensor 11, the temperature (representative temperature) Tm of the motor generator MG detected by a temperature sensor 12, and the like.

[0017] When the electric vehicle 1 is running, the ECU 10 sets the required torque Tr* required for the running of the electric vehicle 1 based on the accelerator opening Acc and the vehicle speed V, and controls the inverter 3 so that the motor generator MG outputs a torque corresponding to the required torque Tr* within the allowable charging power Win and the allowable discharging power Wout of the battery 2 to a pair of drive wheels DW. Also, when braking the electric vehicle 1, the ECU 10 controls the inverter 3 so that the motor generator MG outputs a regenerative braking torque for the share within the allowable charging power Win and the allowable discharging power Wout of the battery 2 to a pair of drive wheels DW. Further, the ECU 10 controls the electric oil pump 9 based on the SOC of the battery 2, the atmospheric pressure Pa, and the temperature Tm of the motor generator MG.

[0018] Also, the charging ECU 15 of the electric vehicle 1 exchanges various information with the ECU 10, the battery ECU 20, etc., and controls the opening and closing of the charging relay DCR. Further, when charging the battery 2 with the power (DC power) from the external charging device 50, the charging ECU 15, if necessary, functions the three-phase coil of the motor generator MG and each phase of the inverter 3 as a multiphase boost converter in cooperation with the ECU 10. That is, in the electric vehicle 1, when charging the battery 2 with the power from the external charging device 50, by switching and controlling a plurality of transistors of the inverter 3, the power supplied to the charging inlet CI is boosted by the multiphase boost converter, and the battery 2 can be charged with the boosted power.

[0019] Subsequently, with reference to FIG. 2, the control procedure of the electric oil pump 9 by the ECU 10 will be described.

[0020] Figure 2 is a flowchart showing a routine that is executed by ECU 10 at predetermined time intervals (micro time intervals) while the electric vehicle 1 is in system startup. When the execution timing of the routine in Figure 2 arrives, ECU 10 acquires the information necessary for processing and then determines whether it is possible to normally supply the working oil O from the electric oil pump 9 to the motor generator MG (step S100). If there is no abnormality in the electric oil pump 9 and the electronic devices and sensors related to the operation of the electric oil pump 9, such as the battery ECU 20 and the temperature sensor 12, are normal, ECU 10 determines that it is possible to normally supply the working oil O from the electric oil pump 9 to the motor generator MG (step S110: YES) and acquires the SOC of the battery 2 from the battery ECU 20, the atmospheric pressure Pa from the atmospheric pressure sensor 11, and the temperature Tm of the motor generator MG from the temperature sensor 12 (step S120). When the atmospheric pressure Pa cannot be detected from the atmospheric pressure sensor 11 due to some abnormality or the like, the atmospheric pressure Pa may be calculated based on the altitude of the own vehicle position of the electric vehicle 1 acquired by a navigation system (not shown).

[0021] Next, ECU 10 determines whether the SOC of the battery 2 acquired in step S120 exceeds a predetermined threshold value Sref (for example, about 60%) (step S130). If the SOC of the battery 2 exceeds the threshold value Sref (step S130: YES), ECU 10 determines whether it is necessary to operate the electric oil pump 9 in order to ensure the dielectric withstand voltage of the motor generator MG based on the SOC, the atmospheric pressure Pa, and the temperature Tm of the motor generator MG (step S140).

[0022] In this embodiment, in the range where the SOC exceeds the threshold value Sref, for each of a plurality of SOCs, a determination map (not shown) that defines the atmospheric pressure Pa and the temperature Tm of the motor generator MG (a combination of both) for operating the electric oil pump 9 to ensure the dielectric withstand voltage of the motor generator MG is prepared. In step S140, the ECU 10 reads out the determination map corresponding to the SOC acquired in step S120, and determines whether to operate the electric oil pump 9 based on the map, the atmospheric pressure Pa, and the temperature Tm acquired in step S120. Note that the determination map used in step S140 is created in advance through experiments and analysis such that the range for operating the electric oil pump 9 increases as the SOC increases, the operation of the electric oil pump 9 is required more as the atmospheric pressure Pa increases, and the operation of the electric oil pump 9 is required more as the temperature Tm increases.

[0023] If it is determined in the determination process of step S140 that it is not necessary to operate the electric oil pump 9 (step S150: NO), the ECU 10 temporarily ends the routine of FIG. 2 at that time. Further, if it is determined in the determination process of step S140 that it is necessary to operate the electric oil pump 9 (step S150: YES), the ECU 10 sets the operation time of the electric oil pump 9, that is, the time required to supply the hydraulic oil O necessary to ensure the insulation performance from the electric oil pump 9 to the motor generator MG, based on the atmospheric pressure Pa and the temperature Tm acquired in step S120 (step S160).

[0024] In this embodiment, an operation time setting map (not shown) that defines the relationship between the atmospheric pressure Pa and the temperature Tm and the operation time of the electric oil pump 9 necessary to ensure the insulation performance in the motor generator MG has been created in advance through experiments and analysis. In step S160, the ECU 10 derives the operation time of the electric oil pump 9 corresponding to the atmospheric pressure Pa and the temperature Tm acquired in step S120 from the operation time setting map. Then, the ECU 10 controls the electric oil pump 9 to operate for the operation time set in step S160 (step S170), and temporarily ends the routine of FIG. 2.

[0025] On the other hand, in step S100, if it is determined that some abnormality has occurred in the electric oil pump 9, or necessary information cannot be obtained from the battery ECU 20, the temperature sensor 12, etc., and the working oil O cannot be normally supplied from the electric oil pump 9 to the motor generator MG (step S100: NO), the ECU 10 executes the process of step S180 and temporarily ends the routine of FIG. 2. In step S180, the ECU 10 transmits a command signal to the battery ECU 20 so as to reduce the allowable charging power Win of the battery 2 (make the absolute value smaller) compared to when the working oil O is normally supplied from the electric oil pump 9 to the motor generator MG in order to reduce the regenerative braking torque output by the motor generator MG during the running of the electric vehicle 1. In this embodiment, when it is determined that the working oil O cannot be normally supplied from the electric oil pump 9 to the motor generator MG, the allowable charging power Win is reduced to a fixed value with a predetermined small absolute value.

[0026] Furthermore, in step S180, the ECU 10 changes the charging conditions when charging the battery 2 with the power from the external charging device 50. That is, in step S180, the ECU 10 transmits a command signal to the charging ECU 15 so as to lower the target SOC and the upper limit charging voltage Vlim when charging the battery 2 with the power from the external charging device 50 as compared with when the hydraulic oil O is normally supplied from the electric oil pump 9 to the motor generator MG. In the present embodiment, the target SOC is decreased from a value (for example, 80%) when the hydraulic oil O is normally supplied from the electric oil pump 9 to the motor generator MG to a predetermined fixed value (for example, 60%). Also, the upper limit charging voltage Vlim is decreased to a value corresponding to the atmospheric pressure Pa (altitude) that enables insulation to be ensured in the motor generator MG without the supply of the hydraulic oil O from the electric oil pump 9.

[0027] As described above, when the ECU 10, which is a control device of the electric vehicle 1, can no longer normally supply the insulating hydraulic oil O (oil) from the electric oil pump 9 to the motor generator MG (step S100: NO), it restricts the allowable charging power Win of the battery 2, the target SOC, and the upper limit charging voltage Vlim when charging the battery 2 with the power from the external charging device 50 to be smaller than when the hydraulic oil O is normally supplied from the electric oil pump 9 to the motor generator MG (step S180). Thereby, the voltage applied to the motor generator MG (coil) that exchanges power with the battery 2 can be restricted within a range where insulation is ensured in the motor generator MG. As a result, in the electric vehicle 1, even when the insulating hydraulic oil O cannot be normally supplied from the electric oil pump 9 to the motor generator MG, it becomes possible to favorably suppress the occurrence of insulation failure (dielectric breakdown) in the motor generator MG.

[0028] Moreover, the invention of the present disclosure is not limited to the above embodiments, and it goes without saying that various modifications can be made within the scope of the disclosure. Further, the above embodiments are merely specific forms of the invention described in the summary section of the invention, and do not limit the elements of the invention described in the summary section of the invention.

Industrial Applicability

[0029] The invention of the present disclosure can be used in the manufacturing industry of electric vehicles and the like.

Explanation of Signs

[0030] 1 Electric vehicle, 2 Battery, 3 Inverter, 7 Transaxle case, 8 Strainer, 9 Electric oil pump, 10 Electronic control unit (ECU), 11 Atmospheric pressure sensor, 12 Temperature sensor, 50 External charging device, MG Motor generator, O Working oil (oil), R Rotor, S Stator.

Claims

【Claim 1】 A control device for an electric vehicle, comprising: an electric motor, a battery that exchanges power with the electric motor, and an electric oil pump that supplies insulating oil to the electric motor, a control device for an electric vehicle that, when the oil cannot be normally supplied from the electric oil pump to the electric motor, restricts the allowable charging power of the battery to be smaller than when the oil is normally supplied from the electric oil pump to the electric motor.

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