electric vehicles

Abstract

Even if a welding abnormality is diagnosed or suspected to have occurred in the negative electrode relay during a system shutdown, the appropriate response will be taken once the welding abnormality is resolved. [Solution] When starting the system after a welding diagnosis of the system main relay during system shutdown has determined that there is a possibility of welding on the negative electrode relay, the system main relay is turned off and the leakage detection circuit is activated, and the negative electrode relay is turned on and off. Based on the voltage change of the leakage detection circuit when the negative electrode relay is turned on and off, a welding abnormality of the negative electrode relay is diagnosed, and if it is determined that there is no welding abnormality on the negative electrode relay, the system is started by normal operation.

Description

Technical Field

[0005] ,

[0001] The present disclosure relates to an electric vehicle, and more particularly to an electric vehicle having a system main relay attached to a power line connected to a battery.

Background Art

[0002] <00000​​​​​​​​​​​​​​​​​​​​​​​​​​​The primary purpose of the electric vehicle disclosed herein is to respond more appropriately when a welding abnormality is diagnosed as occurring or potentially occurring in the negative electrode relay during a system shutdown, and when the welding abnormality is subsequently resolved. [Means for solving the problem]

[0006] The electric vehicle of this disclosure employs the following means to achieve the main objective described above.

[0007] The electric vehicle disclosed herein is A battery connected to the power line, A motor for driving that exchanges power with the battery via the aforementioned power line, A system main relay is installed between the battery and the motor and has a positive-side relay attached to the positive-side line of the power line, a negative-side relay attached to the negative-side line of the power line, and a pre-charge circuit connected in parallel to the negative-side relay on the negative-side line. A leakage current detection circuit connected to the negative terminal of the aforementioned battery, A control device that drives and controls the motor, as well as the system main relay and the leakage current detection circuit, An electric vehicle equipped with, When the control device starts the system after diagnosing the possibility of welding in the negative electrode relay based on welding diagnosis of the system main relay during system shutdown, it turns off the system main relay and activates the leakage detection circuit, then turns the negative electrode relay on and off, diagnoses welding abnormality in the negative electrode relay based on the voltage change of the leakage detection circuit when the negative electrode relay is turned on and off, and if it diagnoses that there is no welding abnormality in the negative electrode relay, it starts the system in normal operation. It is characterized by the following:

[0008] In the electric vehicle of this disclosure, when the system is started after a welding diagnosis of the system main relay during system shutdown indicates a possible welding issue with the negative electrode relay, the system main relay is turned off and the leakage detection circuit is activated. The negative electrode relay is then switched on and off, and a welding abnormality of the negative electrode relay is diagnosed based on the voltage change of the leakage detection circuit when the negative electrode relay is switched on and off. If it is determined that there is no welding abnormality in the negative electrode relay, the system is started using normal operation. In this way, even if a welding abnormality has occurred or is suspected to have occurred in the negative electrode relay during system shutdown, the system is diagnosed for welding abnormalities in the negative electrode relay during subsequent system startup. If it is determined that there is no welding abnormality in the negative electrode relay, the system is started using normal operation. Therefore, a more appropriate response can be taken when the welding abnormality of the negative electrode relay is resolved after system shutdown. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing the configuration of an electric vehicle 20 as one embodiment of the present disclosure. [Figure 2] This flowchart shows an example of system startup processing performed by the electronic control unit 50. [Figure 3] This is an explanatory diagram showing an example of the time variation of the startup request when the system starts up, the system main relay 42, the current Ib from the battery 36, the voltage VL of the capacitor 44, and the leakage current peak value. [Modes for carrying out the invention]

[0010] Next, embodiments for implementing this disclosure will be described. Figure 1 is a schematic diagram showing the configuration of an electric vehicle 20 as one embodiment of this disclosure. As shown in the figure, the electric vehicle 20 comprises a motor 32, a power control unit (hereinafter referred to as "PCU") 34, a battery 36, a system main relay 42, a leakage current detection circuit 46, and an electronic control unit 50.

[0011] The motor 32 is configured as a synchronous regenerative motor and comprises a rotor with embedded permanent magnets and a stator around which three-phase coils are wound. The rotor of this motor 32 is connected to a drive shaft 26 which is connected to the drive wheels 22a and 22b via a differential gear 24.

[0012] The PCU34 consists of a boost circuit that increases the voltage of the power from the battery 36, and an inverter that converts the DC power from the boost circuit into three-phase AC power and applies it to the motor 32.

[0013] The battery 36 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery and is connected to the power line 40.

[0014] A system main relay 42 is installed on the power line 40. This system main relay 42 has a positive-side relay SMRB provided on the positive bus of the power line 40, a negative-side relay SMRG provided on the negative bus of the power line 40, and a pre-charge circuit in which a pre-charge resistor R and a pre-charge relay SMRP are connected in series to bypass the negative-side relay SMRG. A smoothing capacitor 44 is connected to the positive and negative buses of the power line 40.

[0015] The leakage current detection circuit 46 consists of a grounded transmitter 47 and a resistor 48 connected to the transmitter 47 and the negative terminal of the battery 36, and detects leakage current in the power supply circuit including the battery 36.

[0016] The electronic control unit 50 is configured as a microprocessor centered around a CPU (not shown), and in addition to the CPU, it includes ROM for storing processing programs, RAM for temporarily storing data, flash memory, input / output ports, communication ports, etc.

[0017] Signals from various sensors are input into the electronic control unit 50 via the input ports. Examples of the signals input into the electronic control unit 50 include the rotational position θm from a rotational position detection sensor (e.g., resolver) 32a that detects the rotational position of the rotor of the motor 32, the phase currents iu, iv, iw from a current sensor (not shown) attached to the three-phase power line connected to the motor 32, the voltage Vb from a voltage sensor 36a attached between the terminals of the battery 36, the current Ib from a current sensor 36b attached to the output terminal of the battery 36, the voltage VL of the capacitor 44 (power line 40) from a voltage sensor 44a attached between the terminals of the capacitor ς4, the leakage wave height value Vf from a voltage sensor 49 of the leakage detection circuit 46, and so on. Further, since the electronic control unit 50 also functions as a drive control device for the vehicle, it also inputs information necessary for system startup and information necessary for travel control, such as the ignition signal IG from the ignition switch 60, the shift position SP from a shift position sensor 62 that detects the operation position of the shift lever 61, the accelerator opening Acc from an accelerator pedal position sensor 64 that detects the depression amount of the accelerator pedal 63, the brake pedal position BP from a brake pedal position sensor 66 that detects the depression amount of the brake pedal 65, the vehicle speed V from a vehicle speed sensor 67, and the like.

[0018] Various control signals are output from the electronic control unit 50 via the output ports. Examples of the signals output from the electronic control unit 50 include switching control signals to the transistors of the boost circuit and inverter (not shown) of the PCU 34, drive control signals to the system main relay 42, display signals to the display 70 arranged on the instrument panel in front of the driver's seat, and the like.

[0019] Next, we will describe the operation of the electric vehicle 20 of the embodiment configured in this way, particularly the operation when the system is started after a welding abnormality diagnosis of the system main relay 42 performed during system shutdown has determined that a welding abnormality has occurred or is likely to occur in the negative electrode relay SMRG. Figure 2 is a flowchart showing an example of the system startup process performed by the electronic control unit 50. When a welding abnormality diagnosis of the system main relay 42 has determined that a welding abnormality has occurred or is likely to occur in the negative electrode relay SMRG, a history to that effect is stored.

[0020] When the system startup process is executed, the electronic control unit 50 first determines whether there is a history of a welding abnormality in the negative electrode relay SMRG, or a possibility thereof, as diagnosed by the welding abnormality diagnosis of the system main relay 42 performed when the system was stopped (step S100). If it is determined that there is no history of a welding abnormality in the negative electrode relay SMRG, the system is started normally (step S160) and this process is terminated. In a normal system startup, the negative electrode relay SMRG of the system main relay 42 is kept off, the positive electrode relay SMRB is turned on, and the pre-charge relay SMRP is turned on. In this state, the system waits until the voltage VL of the capacitor 44 is close to the voltage of the battery 36, and when the voltage VL of the capacitor 44 is close to the voltage of the battery 36, the negative electrode relay SMRG is turned on, and the pre-charge relay SMRP is turned off, and other abnormality diagnosis processes are performed to complete the system startup.

[0021] When it is determined in step S100 that there is a history of welding abnormality in the negative-side relay SMRG, the leakage detection circuit 46 is operated with the system main relay 42 turned off, and the leakage wave height value Vf1 detected by the voltage sensor 49 is stored (step S110). Subsequently, the negative-side relay SMRG is turned on (step S120), and the leakage wave height value Vf2 detected again by the voltage sensor 49 is stored (step S130). Then, the negative-side relay SMRG is turned off (step S140), and it is determined whether there is a change in the leakage wave height value Vf when the negative-side relay SMRG is turned on and off based on the leakage wave height value Vf1 and the leakage wave height value Vf1 (step S150). When it is determined that there is a change in the leakage wave height value Vf when the negative-side relay SMRG is turned on and off, it is judged that no welding abnormality has occurred in the negative-side relay SMRG, and the system is normally started (step S160), and this process is terminated. On the other hand, when it is determined that there is no change in the leakage wave height value Vf when the negative-side relay SMRG is turned on and off, it is judged that a welding abnormality has occurred in the negative-side relay SMRG, and the system startup is prohibited (step S170), and this process is terminated. When the system startup is prohibited, a message to that effect, such as "The system cannot be started due to an abnormality.", is displayed on the display 70 and voice output is performed to notify the driver.

[0022] Figure 3 is an explanatory diagram showing an example of the time changes in the startup request, the system main relay 42, the current Ib from the battery 36, the voltage VL of the capacitor 44, and the leakage wave peak when the system is started when there is a history of welding abnormality in the negative electrode relay SMRG. The leakage wave peak Vf1 is stored in time T1 when the system main relay 42 is off immediately after the system startup process starts, and the negative electrode relay SMRG is turned off in time T2 immediately after that. Then, in conjunction with this, the leakage wave peak Vf2 is stored in time T3. The negative electrode relay SMRG is turned off in time T4, and a normal system startup request is made in transition time T5 after confirming that there is no welding abnormality in the negative electrode relay SMRG, and the positive electrode relay SMRB and the pre-charge relay SMRP of the system main relay 42 are turned on, and charging of the capacitor 44 begins. When the voltage VL of capacitor 44 becomes close to the voltage Vb of battery 36, the negative side relay SMRG is turned on and the pre-charge relay SMP is turned off, ending the ON operation of the system main relay 42 during system startup.

[0023] In the electric vehicle 20 of the embodiment described above, if there is a history of a diagnosis result indicating that a welding abnormality has occurred or is possible in the negative electrode relay SMRG during system shutdown, when the system is started again, the system main relay 42 is turned off, and the leakage current detection circuit 46 is activated to turn the negative electrode relay SMRG on and off to determine whether or not there is a change in the leakage current peak value Vf. If it is determined that there is a change in the leakage current peak value Vf, it is determined that there is no welding abnormality in the negative electrode relay SMRG, and the system is started normally. On the other hand, if it is determined that there is no change in the leakage current peak value Vf, it is determined that a welding abnormality has occurred in the negative electrode relay SMRG, and the system is not started. This allows for a more appropriate response when a welding abnormality has occurred or is possible in the negative electrode relay SMRG during system shutdown, even if the welding abnormality is subsequently resolved.

[0024] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on the main elements of the embodiment and the means for solving the problem will be explained. In the embodiment, the power line 40 corresponds to "power line", the battery 36 corresponds to "battery", the motor 32 corresponds to "motor", the positive side relay SMRB corresponds to "positive side relay", the negative side relay SMOG corresponds to "negative side relay", the precharge circuit consisting of the precharge relay SMRP and the precharge resistor R corresponds to "precharge circuit", the leakage detection circuit 46 corresponds to "leakage detection circuit", and the electronic control unit 50 corresponds to "control device".

[0025] Furthermore, 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 is merely an example to specifically explain the form in which the embodiment implements the invention described in the section on means for solving the problem, and does not limit the elements of the invention described in the section on means for solving the problem. In other words, the interpretation of the invention described in the section on means for solving the problem should be based on the description in that section, and the embodiment is merely one specific example of the invention described in the section on means for solving the problem.

[0026] Although the present disclosure has been described above using embodiments, the present disclosure is not limited in any way to these embodiments, and can of course be implemented in various forms without departing from the gist of the present disclosure. [Industrial applicability]

[0027] This disclosure can be used in industries such as electric vehicle manufacturing. [Explanation of symbols]

[0028] 20 Electric vehicle, 22a, 22b Drive wheels, 24 Differential gear, 26 Drive shaft, 32 Motor, 32a Rotation position detection sensor, 34 PCU, 36 Battery, 36a Voltage sensor, 36b Current sensor, 40 Power line, 42 System main relay, 44 Capacitor, 44a Voltage sensor, 46 Leakage current detection circuit, 47 Transmitter, 48 Resistor, 49 Voltage sensor, 50 Electronic control unit, 60 Ignition switch, 61 Shift lever, 62 Shift position sensor, 63 Accelerator pedal, 64 Accelerator pedal position sensor, 65 Brake pedal, 66 Brake position sensor, 67 Vehicle speed sensor, 70 Display, R Pre-charge resistor, SMRB Positive side relay, SMRG Negative side relay, SMRP Pre-charge relay.

Claims

[Claim 1] A battery connected to the power line, A motor for driving that exchanges power with the battery via the aforementioned power line, A system main relay is installed between the battery and the motor and has a positive-side relay attached to the positive-side line of the power line, a negative-side relay attached to the negative-side line of the power line, and a pre-charge circuit connected in parallel to the negative-side relay on the negative-side line. A leakage current detection circuit connected to the negative terminal of the aforementioned battery, A control device that drives and controls the motor, as well as the system main relay and the leakage current detection circuit, An electric vehicle equipped with, When the control device starts the system after diagnosing the possibility of welding in the negative electrode relay based on welding diagnosis of the system main relay during system shutdown, it turns off the system main relay and activates the leakage detection circuit, then turns the negative electrode relay on and off, diagnoses welding abnormality in the negative electrode relay based on the voltage change of the leakage detection circuit when the negative electrode relay is turned on and off, and if it diagnoses that there is no welding abnormality in the negative electrode relay, it starts the system in normal operation. An electric vehicle characterized by the following features.

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