Electric vehicles

Abstract

To inhibit an abnormality from occurring in an electric device other than an inverter when an abnormality occurs in the inverter which drives a motor and driving of the inverter is stopped.SOLUTION: An electric vehicle includes: a motor connected to driving wheels; an inverter which drives the motor and has a switching element; a power storage device connected to the inverter through a power line; at least one electric device connected to the power line and having the switching element; and a control device. The control device stops driving of all of the inverter and the at least one electric device described above when a rotation number of the motor is higher than or equal to a predetermined rotation number when an abnormality occurs in the inverter.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an electric vehicle. [Background technology]

[0002] Conventionally, an electric vehicle of this type has been proposed that includes a battery, a front motor that drives the front wheels, a front inverter that converts the battery's DC power into AC power and supplies it to the front motor, a rear motor that drives the rear wheels, and a rear inverter that converts the battery's DC power into AC power and supplies it to the rear motor (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-61414 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned electric vehicle, when the front motor and the rear motor are driven and the vehicle is traveling at high speed, if an abnormality occurs in the front inverter and the front inverter is stopped, the back electromotive voltage generated by the rotation of the front motor may cause the voltage of the power line connecting the front inverter, the rear inverter, and the battery to become considerably high. In this case, if the switching element of the rear inverter is switched, an abnormality may also occur in the rear inverter.

[0005] The main object of the electric vehicle of the present invention is to prevent abnormalities from occurring in electric power devices other than the inverter when an abnormality occurs in the inverter that drives the motor and the drive of the inverter is stopped. [Means for solving the problem]

[0006] In order to achieve the above-mentioned main object, the electric vehicle of the present invention employs the following means.

[0007] The electric vehicle of the present invention comprises: A motor coupled to the drive wheels; an inverter that drives the motor and has a switching element; a power storage device connected to the inverter via a power line; At least one power device connected to the power line and having a switching element; A control device; An electric vehicle comprising: the control device stops driving the inverter and all of the at least one electric device when a rotation speed of the motor is equal to or higher than a predetermined rotation speed during an abnormality in the inverter; The gist of the present invention is as follows.

[0008] In the electric vehicle of the present invention, when the rotation speed of the motor is equal to or higher than a predetermined rotation speed during an abnormality in the inverter, the inverter and the at least one electric device are all stopped from being driven. This makes it possible to prevent an abnormality from occurring in the at least one electric device when the voltage of the power line becomes considerably high due to a back electromotive force generated by the rotation of the motor when an abnormality occurs in the inverter and the inverter is stopped from being driven.

[0009] In the electric vehicle of the present invention, the electric vehicle may further include a second motor connected to a second drive wheel different from the drive wheel, the at least one electric device has a second inverter that drives the second motor, and the control device may stop driving the inverter and drive the second inverter when the rotation speed of the motor is less than the predetermined rotation speed due to an abnormality in the inverter. By driving the second inverter so that a torque for evacuation running is output from the second motor, evacuation running can be performed.

[0010] In the electric vehicle of the present invention, the vehicle may further include a second power storage device having a lower rated voltage than the power storage device, the at least one power device having a step-down device capable of stepping down the power of the power line and supplying it to a second power line to which the second power storage device is connected, and the control device may stop driving the inverter and drive the step-down device when the rotation speed of the motor is less than the predetermined rotation speed during an abnormality in the inverter. By driving the step-down device, the power of the power line can be stepped down and supplied to the second power line, and a decrease in the voltage of the second power storage device can be suppressed. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing an outline of the configuration of a hybrid vehicle 20 according to an embodiment of the present invention. [Diagram 2] 2 is a diagram showing an outline of the configuration of an electrical system including motors 32, 44, inverters 34, 46, etc. [Diagram 3] 4 is a flowchart showing an example of an abnormality processing routine executed by the main ECU 70. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Next, a mode for carrying out the present invention will be described using examples. EXAMPLES

[0013] Fig. 1 is a schematic diagram showing the configuration of a hybrid vehicle 20 according to an embodiment of the present invention, and Fig. 2 is a schematic diagram showing the configuration of an electrical system including motors 32, 44 and inverters 34, 46. As shown in Fig. 1, the hybrid vehicle 20 of the embodiment includes a motor 32, an inverter 34, an engine 42, an engine electronic control unit (hereinafter referred to as "engine ECU") 43, a motor 44, an inverter 46, a transmission 48, a step-down device 50, a high-voltage battery 60, a low-voltage battery 62, and a main electronic control unit (hereinafter referred to as "main ECU") 70.

[0014] The motor 32 is configured as a synchronous generator motor having a rotor in which a permanent magnet is embedded and a stator in which a three-phase coil is wound around a stator core. The rotor of the motor 32 is connected to a drive shaft 26f connected to the front wheels 22f via a differential gear 24f. The inverter 34 is used to drive the motor 32 and is connected to the power line 28. As shown in FIG. 2, the inverter 34 has six transistors T11 to T16 as switching elements and six diodes D11 to D16 connected in parallel to the six transistors T11 to T16, respectively. The transistors T11 to T16 are arranged in pairs of two each so as to be on the source side and the sink side with respect to the positive pole line 28p and the negative pole line 28n of the power line 28, respectively. Also, each of the three-phase coils of the motor 32 is connected to each of the connection points of the paired transistors of the transistors T11 to T16. Therefore, when a voltage is applied to the inverter 34, the main ECU 70 adjusts the ratio of the on-time of each pair of transistors T11 to T16, thereby forming a rotating magnetic field in the three-phase coils and rotating the motor 32. A capacitor 35 is attached to the positive line 28p and the negative line 28n of the power line 28. In this embodiment, the inverter 34 and the capacitor 35 are housed in the same case.

[0015] The engine 42 is configured as an internal combustion engine that outputs power using gasoline, diesel, etc. as fuel. As shown in Fig. 1, the crankshaft of the engine 42 is connected to a rotor of a motor 44. The operation of the engine 42 is controlled by an engine ECU 43.

[0016] The engine ECU 43 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports (not shown). Signals from various sensors required for controlling the operation of the engine 42 are input to the engine ECU 43 via the input port. An example of the signal input to the engine ECU 43 is a crank angle θcr from a crank position sensor (not shown) that detects the rotational position of the crankshaft of the engine 42. Various control signals for controlling the operation of the engine 42 are output from the engine ECU 43 via the output port. The engine ECU 24 is connected to the main ECU 70 via the communication port. The engine ECU 43 calculates the rotation speed Ne of the engine 42 based on the crank angle θcr from the crank position sensor.

[0017] The motor 44, like the motor 32, is configured as a synchronous generator motor having a rotor in which a permanent magnet is embedded and a stator in which a three-phase coil is wound around a stator core. The rotor of the motor 44 is connected to the crankshaft of the engine 42 and the input shaft of the transmission 48. The inverter 46 is used to drive the motor 44 and is connected to the power line 28. As shown in FIG. 2, the inverter 46 has six transistors T21 to T26 as switching elements and six diodes D21 to D26 connected in parallel to the six transistors T21 to T26, respectively. The transistors T21 to T26 are arranged in pairs of two each so as to be on the source side and the sink side with respect to the positive line 28p and the negative line 28n of the power line 28, respectively. In addition, each of the three-phase coils of the motor 44 is connected to each of the connection points of the paired transistors of the transistors T21 to T26. Therefore, when a voltage is applied to the inverter 46, the main ECU 70 adjusts the ratio of the on-time of the paired transistors T21 to T26, thereby forming a rotating magnetic field in the three-phase coils and rotating the motor 44. A capacitor 47 is attached to the positive line 28p and the negative line 28n of the power line 28. In this embodiment, the inverter 46, the capacitor 47, and the step-down device 50 are housed in the same case.

[0018] The transmission 48 is configured as an automatic transmission with, for example, 4-speed, 5-speed, or 6-speed, and has an input shaft, an output shaft, a plurality of planetary gears, and a plurality of hydraulically driven friction engagement elements (clutches and brakes). As shown in Fig. 1, the input shaft of the transmission 48 is connected to the rotor of the motor 44, and the output shaft of the transmission 48 is connected to a drive shaft 26r that is connected to the rear wheels 22r via a differential gear 24r. The transmission 48 is controlled by a main ECU 70; specifically, the transmission 48 forms a plurality of forward and reverse gears by engaging and disengaging a plurality of friction engagement elements, and transmits power between the input shaft and the output shaft.

[0019] As shown in FIG. 2, the step-down device 50 includes a first step-down converter 52, a second step-down converter 54, and a capacitor 57. The first step-down converter 52 is connected to the power line 28 and the power line 56, and includes transistors T31 and T32 as two switching elements, two diodes D31 and D32 connected in parallel to the two transistors T31 and T32, respectively, and a reactor L. The transistor T31 is connected to a positive side line 28p of the power line 28. The transistor T32 is connected to the transistor T31 and negative side lines 28n and 56n of the power lines 28 and 56. The reactor L is connected to a connection point between the transistors T31 and T32 and a positive side line 56p of the power line 56. The first step-down converter 52 steps down the power of the power line 28 and supplies it to the power line 56 by adjusting the ratio of the on-time of the transistors T31 and T32 by the main ECU 70. The second step-down converter 54 is connected to the power line 56 and the power line 64, and is controlled by the main ECU 70 to step down the power of the power line 58 and supply it to the power line 64. The second step-down converter 54 may have a similar configuration to the first step-down converter 52, or may have a different configuration, for example, a so-called isolated converter configuration having a transformer. The capacitor 57 is attached to the positive side line 56p and the negative side line 56n of the power line 56.

[0020] The high-voltage battery 60 is configured as a lithium-ion secondary battery, a nickel-hydrogen secondary battery, or the like, with a rated voltage of several hundred volts, and is connected to the power line 28 as shown in Fig. 1. The low-voltage battery 62 is configured as a lithium-ion secondary battery, a nickel-hydrogen secondary battery, a lead-acid battery, or the like, with a rated voltage of about 12 V lower than that of the high-voltage battery 60, and is connected to the power line 64 together with auxiliary devices (e.g., lights, an audio system, a navigation device, etc.) not shown.

[0021] Although not shown, the main ECU 70 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. Signals from various sensors are input to the main ECU 70 via the input ports. Examples of signals input to the main ECU 70 include the rotational position θmf of the rotor of the motor 32 from a rotational position sensor (e.g., resolver) 32a that detects the rotational position of the rotor of the motor 32, and the rotational position θmr of the rotor of the motor 44 from a rotational position sensor (e.g., resolver) 44a that detects the rotational position of the rotor of the motor 44. Examples of signals input to the main ECU 70 include the rotational speeds Nin and Nout of the input and output shafts of the transmission 48 from a rotational speed sensor that detects the rotational speeds of the input and output shafts of the transmission 48. Examples of signals input to the main ECU 70 include the voltage Vb1 of the high-voltage battery 60 from a voltage sensor (e.g., resolver) that is attached between the terminals of the high-voltage battery 60, and the current Ib1 of the high-voltage battery 60 from a current sensor (e.g., resolver) that is attached to the output terminal of the high-voltage battery 60. Other examples of the input signal include the voltage Vb2 of the low-voltage battery 62 from a voltage sensor (not shown) attached between the terminals of the low-voltage battery 62, and the current Ib2 of the low-voltage battery 62 from a current sensor (not shown) attached to the output terminal of the low-voltage battery 62. Other examples of the input signal include a start signal from a start switch 80, a shift position SP from a shift position sensor 82 that detects the operation position of a shift lever 81, an accelerator opening Acc from an accelerator pedal position sensor 84 that detects the amount of depression of an accelerator pedal 83, a brake pedal position BP from a brake pedal position sensor 86 that detects the amount of depression of a brake pedal 85, and a vehicle speed V from a vehicle speed sensor 88.

[0022] Various control signals are output from the main ECU 70 via an output port. Examples of signals output from the main ECU 70 include a control signal to the transistors T11 to T16 of the inverter 34, a control signal to the transistors T21 to T26 of the inverter 46, and a control signal to the transmission 48. Examples of the signals output from the main ECU 70 include a control signal to the transistors T31, T32 of the first step-down converter 52 of the step-down device 50, and a control signal to the second step-down converter 54 of the step-down device 50. As described above, the main ECU 70 is connected to the engine ECU 43 via a communication port. The main ECU 70 calculates the rotation speeds Nmf, Nmr of the motors 32, 44 based on the rotation positions θmf, θmr of the rotors of the motors 32, 44 from the rotation position sensors 34a, 46a.

[0023] In the hybrid vehicle 20 of this embodiment configured as described above, the main ECU 70 and the engine ECU 43 cooperate to control the required torque Td* for driving based on the accelerator opening Acc and the vehicle speed V, and the motor 32 (inverter 34), the engine 42, the motor 44 (inverter 46), and the transmission 48 to drive with the set required torque Td*.

[0024] Next, the operation of the hybrid vehicle 20 of the embodiment thus configured, particularly the operation when an abnormality occurs in the inverter 34, will be described. Here, the abnormality in the inverter 34 may be overheating, or at least one of the transistors T11-T16 or the diodes D11-D16 being stuck on or off. Fig. 3 is a flowchart showing an example of an abnormality processing routine executed by the main ECU 70. This routine is executed repeatedly when an abnormality occurs in the inverter 34.

[0025] 3 is executed, the main ECU 70 first inputs the rotation speed Nmf of the motor 32 (step S100). Here, the rotation speed Nmf of the motor 32 is a value calculated based on the rotation position θmf of the rotor of the motor 32 detected by the rotation speed sensor 32a.

[0026] When the data is input in this manner, the input rotation speed Nmf of the motor 32 is compared with a threshold value Nmfref (step S110). Here, the threshold value Nmfref is a threshold value used to determine whether or not there is a possibility that an abnormality will occur in at least some of the transistors T21-T26, diodes D21-D26, transistors T31, T32, and diodes D31, D32 when the inverter 46 and the first step-down converter 52 are driven (the transistors T21-T26 and the transistors T31, T32 are switched) when the inverter 34 is stopped. This threshold value Nmfref is determined based on the specifications of the transistors T21-T26, diodes D21-D26, transistors T31, T32, and diodes D31, D32. When the inverter 34 is stopped, if a back electromotive force generated by the rotation of the motor 32 is higher than the voltage of the power line 28, power resulting from the back electromotive force is supplied to the power line 28 via the inverter 34 functioning as a rectifier circuit, and the voltage of the power line 28 increases. If the inverter 46 or the first step-down converter 52 of the step-down device 50 is driven when the voltage of the power line 28 is considerably high, there is a possibility that an abnormality will occur in at least some of the transistors T21-T26, the diodes D21-D26, the transistors T31, T32, and the diodes D31, D32. The process of step S110 is performed taking this into consideration.

[0027] When the rotation speed Nmf of the motor 32 is equal to or greater than the threshold value Nmfref in step S110, the inverter 34, the inverter 46, and the step-down device 50 (the first step-down converter 52 and the second step-down converter 54) are all stopped or kept stopped (step S120), and this routine ends. Here, when the inverter 34, the inverter 46, and the first step-down converter 52 are stopped, all of the transistors T11 to T16, T21 to T26, T31, and T32 are turned off. By this processing, when an abnormality occurs in the inverter 34 and the inverter 34 is stopped, it is possible to prevent an abnormality from occurring in at least some of the transistors T21 to T26 and diodes D21 to D26 of the inverter 46 and the transistors T31, T32 and diodes D31, D32 of the first step-down converter 52 when the voltage of the power line 28 becomes considerably high due to the back electromotive voltage generated by the rotation of the motor 32. In this embodiment, at this time, the main ECU 70 causes the engine ECU 43 to execute fuel cut of the engine 42. When the inverters 34 and 46 are stopped, drag torque (torque in a direction that reduces the rotation speeds Nmf and Nmr of the motors 32 and 44) ​​is generated in the motors 32 and 44. Therefore, the vehicle speed V decreases due to the drag torque of the motors 32 and 44 and the braking torque (so-called engine brake) caused by the fuel cut of the engine 42. The main ECU 70 may cause the engine ECU 43 to operate the engine 42 without load (idle operation).

[0028] When the rotation speed Nm of the motor 32 is less than the threshold value Nmfref in step S110, the inverter 34 is stopped or kept stopped, and the inverter 46 and the step-down device 50 (the first step-down converter 52 and the second step-down converter 54) are permitted to be driven (step S130), and this routine ends. In this case, the inverter 46 is driven so that a torque for evacuation travel is output from the motor 44. This makes it possible to perform evacuation travel. In addition, by driving the first step-down converter 52 and the second step-down converter 54, the power of the power line 28 can be supplied to the power line 64 via the power line 56, and the voltage of the low-voltage battery 62 can be prevented from decreasing.

[0029] In the hybrid vehicle 20 of the embodiment described above, when the rotation speed Nmf of the motor 32 is equal to or higher than the threshold value Nmfref during an abnormality in the inverter 34, the inverter 34, the inverter 46, and the step-down device 50 are all stopped. This makes it possible to prevent abnormalities from occurring in at least some of the transistors T21-T26 and diodes D21-D26 of the inverter 46 and the transistors T31, T32 and diodes D31, D32 of the first step-down converter 52 when the voltage of the power line 28 becomes considerably high due to the back electromotive voltage generated by the rotation of the motor 32 when the inverter 34 is stopped due to an abnormality in the inverter 34.

[0030] Furthermore, in the hybrid vehicle 20 of the embodiment, when the rotation speed Nmf of the motor 32 is less than the threshold value Nmfref during an abnormality in the inverter 34, the inverter 34 is stopped and the inverter 46 and the step-down device 50 (first step-down converter 52 and second step-down converter 54) are driven. By driving the inverter 46 so that a torque for evacuation running is output from the motor 44, evacuation running can be performed. Furthermore, by driving the step-down device 50, the power of the power line 28 can be supplied to the power line 64, and the voltage of the low-voltage battery 62 can be prevented from decreasing.

[0031] In the hybrid vehicle 20 of the embodiment, when the rotation speed Nmf of the motor 32 is less than the threshold value Nmfref during an abnormality in the inverter 34, the inverter 34 is stopped and the inverter 46 and the step-down device 50 (first step-down converter 52 and second step-down converter 54) are driven. However, at this time, the inverter 34 and the inverter 46 may be stopped and the step-down device 50 may be driven. Also, at this time, the inverter 34 and the step-down device 50 may be stopped and the inverter 46 may be driven.

[0032] In the hybrid vehicle 20 of the embodiment, the step-down device 50 includes the first step-down converter 52 and the second step-down converter 54. However, the step-down device 50 may include only one step-down converter. That is, the power on the power line 28 may be stepped down by one step-down converter and supplied to the power line 64.

[0033] In the embodiment, as shown in Fig. 1 and Fig. 2, the hybrid vehicle 20 including the motor 32, the inverter 34, the engine 42, the motor 44, the inverter 46, the transmission 48, the step-down device 50 (first step-down converter 52 and second step-down converter 54), the high-voltage battery 60, and the low-voltage battery 62 has been described. However, the hardware configuration of the hybrid vehicle 20 may not include the motor 44 and the inverter 46. The hardware configuration of the hybrid vehicle 20 may not include the step-down device 50 (without transferring power between the power line 28 and the power line 64), but may include an alternator that generates power using power from the engine 42 and supplies the power to the power line 64. The hardware configuration of the hybrid vehicle 20 may not include the engine 42 or may not include the engine 42 and the transmission 48.

[0034] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem will be described. In the embodiment, the motor 32 corresponds to the "motor", the inverter 34 corresponds to the "inverter", the high-voltage battery 60 corresponds to the "electricity storage device", the inverter 46 and the step-down device 50 correspond to "at least one electric power device", and the main ECU 70 corresponds to the "control device". In addition, the motor 44 corresponds to the "second motor", and the inverter 46 corresponds to the "second inverter". Furthermore, the low-voltage battery 62 corresponds to the "second electricity storage device", and the step-down device 50 corresponds to the "step-down device".

[0035] The correspondence between the main elements of the Examples and the main elements of the invention described in the Summary of the Problem column does not limit the elements of the invention described in the Summary of the Problem column, since the Examples are examples for specifically explaining the mode for implementing the invention described in the Summary of the Problem column. In other words, the interpretation of the invention described in the Summary of the Problem column should be based on the description in that column, and the Examples are merely a specific example of the invention described in the Summary of the Problem column.

[0036] Although the form for carrying out the present invention has been described above using examples, the present invention is not limited to these examples in any way, and it goes without saying that the present invention can be carried out in various forms without departing from the gist of the present invention. [Industrial Applicability]

[0037] The present invention can be used in the electric vehicle manufacturing industry and the like. [Explanation of symbols]

[0038] 20 hybrid vehicle, 22 engine, 22f front wheel, 22r rear wheel, 24f, 24r differential gear, 26f, 26r drive shaft, 28 power line, 28n negative side line, 28p positive side line, 32 motor, 32a rotation speed sensor, 34 inverter, 34a rotation position sensor, 35 capacitor, 42 engine, 43 engine ECU, 44 motor, 46 inverter, 47 capacitor, 48 transmission, 50 step-down device, 52 first step-down converter, 54 second step-down converter, 56 power line, 56n negative side line, 56p positive side line, 57 capacitor, 60 high voltage battery, 62 low voltage battery, 64 power line, 67a voltage sensor, 70 main ECU, 80 start switch, 81 shift lever, 82 shift position sensor, 83 Accelerator pedal, 84 accelerator pedal position sensor, 85 brake pedal, 86 brake pedal position sensor, 88 vehicle speed sensor, D11 to D16, D21 to D26, D31, D32 diodes, T11 to T16, T21 to T26, T31, T32 transistors.

Claims

1. A motor coupled to the drive wheels; an inverter that drives the motor and has a switching element; a power storage device connected to the inverter via a power line; At least one power device connected to the power line and having a switching element; A second storage device having a lower rated voltage than the storage device; A control device; An electric vehicle comprising: the at least one electric power device has a step-down device capable of stepping down the electric power of the electric power line and supplying the power to a second electric power line to which the second power storage device is connected; the control device stops driving the inverter and all of the at least one electric power device when a rotation speed of the motor is equal to or higher than a predetermined rotation speed during an abnormality in the inverter, and stops driving the inverter and drives the step-down device when a rotation speed of the motor is lower than the predetermined rotation speed during an abnormality in the inverter. Electric vehicle.

2. The electric vehicle according to claim 1, A second motor is connected to a second drive wheel different from the drive wheel, the at least one electric power device includes a second inverter that drives the second motor; the control device, when the rotation speed of the motor is lower than the predetermined rotation speed due to an abnormality in the inverter, stops driving the inverter and drives the second inverter. Electric vehicle.

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