JP2023074418A - Abnormality determination method - Google Patents

Abstract

To suppress erroneous determination when abnormality in an electric circuit is determined.SOLUTION: An abnormality determination method for determining abnormality in an electric circuit during regeneration by a rotary electric machine includes: a limiting step of limiting an amount of regeneration when there is deviation between a current value of a regeneration current detected by a current sensor during regeneration and a current command value of the regeneration current; and a determination step of determining that abnormality has occurred in the electric circuit when a voltage value of a smoothing capacitor exceeds a predetermined value after limiting the amount of regeneration by the limiting step.SELECTED DRAWING: Figure 5

Description

The present invention relates to an abnormality determination method.

In Patent Document 1, a motor drive system having a battery and an inverter is provided with a current breaker between the battery and the inverter, and whether or not the current breaker operates is determined based on the degree of change in the voltage value of the smoothing capacitor. A method for determining is disclosed.

JP 2012-085455 A

In the configuration described in Patent Document 1, although the voltage of the smoothing capacitor is detected by the voltage sensor, the voltage value obtained by the voltage sensor is the actual capacitor voltage superimposed with noise from the outside. Difficult to separate. Therefore, in the abnormality determination method based on the voltage fluctuation of the smoothing capacitor, there is a possibility of erroneously determining that there is an abnormality when an instantaneous voltage fluctuation due to external noise is detected.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an abnormality determination method capable of suppressing an erroneous determination when determining an abnormality in an electric circuit.

The present invention is an anomaly judgment method for judging an anomaly in an electric circuit during regeneration by a rotating electrical machine, wherein there is a discrepancy between a current value of a regenerated current detected by a current sensor during regeneration and a current command value of the regenerated current. a limiting step for limiting the amount of regeneration, and when the voltage value of the smoothing capacitor exceeds a predetermined value after limiting the amount of regeneration by the limiting step, it is determined that an abnormality has occurred in the electric circuit. and a judgment step of judging.

In the present invention, a primary determination is made according to the deviation between the regenerative current measured value and the regenerative current command value. Make the next decision. In the primary determination, when a change due to instantaneous noise is detected, the amount of regeneration is limited to suppress the voltage change, and the system does not stop. In this way, erroneous determination can be suppressed by making the abnormality determination into a double structure.

FIG. 1 is a diagram schematically showing the configuration of the drive system of the first embodiment. FIG. 2 is a diagram showing temporal changes in the voltage value of the smoothing capacitor. FIG. 3 is a flowchart showing abnormality determination processing of the first embodiment. FIG. 4 is a time chart showing changes in capacitor voltage in the first embodiment. FIG. 5 is a diagram schematically showing the configuration of the drive system of the second embodiment. FIG. 6 is a diagram showing temporal changes in the current value of the PN line. FIG. 7 is a flowchart showing abnormality determination processing according to the second embodiment. FIG. 8 is a time chart showing changes in capacitor voltage in the second embodiment.

An abnormality determination method according to an embodiment of the present invention will be specifically described below with reference to the drawings. In addition, this invention is not limited to embodiment described below.

(First embodiment)
The abnormality determination method of the first embodiment is a determination method for detecting an abnormality in a drive system that drives a motor.

FIG. 1 is a diagram schematically showing the configuration of the drive system of the first embodiment. The drive system 1 of the first embodiment includes a battery 2, an inverter 3, a motor 4, a smoothing capacitor 5, a voltage sensor 6, an SMR (System Main Relay) 7, a resistor 8, and a controller 9. there is

Battery 2 is a DC power source and is a storage battery that can be charged and discharged. This battery 2 is composed of a secondary battery such as a lithium ion battery or a nickel hydrogen battery. Also, the battery 2 can be configured by an assembled battery configured by a plurality of single cells. During power running, the battery 2 supplies power to the inverter 3 to generate driving force for the vehicle. During regeneration, the battery 2 can store power generated by the motor 4 .

The inverter 3 is a power conversion device that converts DC power from the battery 2 into AC power and supplies the AC power to the motor 4 . This inverter 3 is connected to the PN line. The inverter 3 is configured by an inverter circuit having a plurality of switching elements so that three-phase currents can be applied to the three-phase coils of the motor 4 . An inverter circuit is an electric circuit that converts DC power into AC power by switching each switching element for each phase (U-phase, V-phase, W-phase). The inverter 3 has 6 switching elements and 6 diodes. Two switching elements are arranged in pairs so as to be on the source side and the sink side with respect to the positive bus line and the negative bus line of the PN line. The diodes are connected in parallel in opposite directions to their corresponding switching elements. Furthermore, in the inverter 3, each of the three-phase coils of the motor 4 is connected to each connection point between the paired switching elements.

The motor 4 is a power source for running, and is a rotating electric machine (motor generator) having the functions of an electric motor and a generator. The motor 4 is composed of a synchronous generator-motor having a rotor in which permanent magnets are embedded and a stator in which three-phase coils (U-phase, V-phase, and W-phase) are wound. A three-phase coil wound around the stator of the motor 4 is electrically connected to the inverter 3 . The vehicle also includes a power transmission device that transmits the power output from the motor 4 to the wheels, and drives the wheels with the power output from the motor 4 .

Smoothing capacitor 5 suppresses voltage fluctuations caused by the switching operation of inverter 3 . A voltage sensor 6 acquires information about the voltage value of the smoothing capacitor 5 . Smoothing capacitor 5 and voltage sensor 6 are arranged in a circuit (high-voltage side circuit) closer to inverter 3 than SMR 7, and are connected to the positive and negative bus lines of the PN line.

SMR 7 is a current breaker electrically connected between battery 2 and inverter 3 . The SMR 7 includes an SMR 7A provided on the positive bus of the PN line, an SMR 7B provided on the negative bus of the PN line, and an SMR 7C connected in series with the resistor 8. FIG. SMR7C and resistor 8 are connected in parallel with SMR7B. SMR7A, SMR7B, and SMR7C are simply referred to as SMR7 when they are not distinguished from each other.

Also, the SMR 7 is opened (OFF) or closed (ON) according to a control signal from the controller 9 . When the SMR 7 is closed, the battery 2 and the inverter 3 are brought into a conducting state, and electric power can be transferred between the battery 2 and the inverter 3 . When the SMR 7 is opened, the battery 2 and the inverter 3 are electrically cut off.

The controller 9 is an electronic control unit (ECU) that controls the drive system 1 . This electronic control unit includes a microcomputer having a CPU, a RAM, a ROM, and an input/output interface. The controller 9 performs signal processing according to a program pre-stored in the ROM. Signals from various sensors are input to the controller 9 . Signals input to the controller 9 include a vehicle speed signal from a vehicle speed sensor that detects the vehicle speed, a resolver signal from a rotation angle sensor that detects the rotation angle of the motor 4, a voltage value from the voltage sensor 6, and the like. The controller 9 executes various controls based on signals input from various sensors.

For example, the controller 9 performs arithmetic processing for motor control, such as calculating the rotation speed of the motor 4 based on the resolver signal. As a result of the calculation, a command signal for controlling the inverter 3 is output from the controller 9 to the inverter 3 . This command signal includes a switching control signal to the switching element of inverter 3 . Thus, the controller 9 controls the voltage and current applied to the motor 4 by controlling the inverter 3 .

In the drive system 1 configured as described above, if the SMR 7 fails during regeneration by the motor 4, the charging of the smoothing capacitor 5 may cause the high-voltage components to exceed the withstand voltage. In order to prevent this, the controller 9 is configured to detect an abnormality in the electric circuit.

Specifically, an abnormal state is assumed in which the SMR 7 fails during regeneration and the SMR 7 becomes open. In this case, the regenerated power from the motor 4 to the battery 2 flows into the smoothing capacitor 5, and the voltage of the smoothing capacitor 5 increases according to the amount of regeneration. Therefore, the controller 9 determines abnormality of the PN line based on the voltage of the smoothing capacitor 5 acquired by the voltage sensor 6 . The trigger for abnormality detection has a dual structure including a primary determination and a secondary determination. The primary determination is made based on the degree of change in the voltage of the smoothing capacitor 5 while the inverter 3 is regenerating power from the motor 4 . A secondary determination is made based on a comparison between the voltage of the smoothing capacitor 5 and a threshold. Then, the regeneration amount is limited according to the result of the primary determination, and the operation of the inverter 3 is stopped according to the result of the secondary determination.

FIG. 2 is a diagram showing temporal changes in the voltage value of the smoothing capacitor. When an open failure occurs in which the SMR 7 is in an open state, the regenerated power accumulates in the smoothing capacitor 5, so that the voltage value of the smoothing capacitor 5 increases and the amount of change in the capacitor voltage increases. Therefore, a primary determination based on this amount of change and a secondary determination based on the capacitor voltage are performed. In the primary determination, it is determined that there is an abnormality when the amount of increase in voltage within a certain period of time exceeds a threshold. In the secondary determination, when the capacitor voltage exceeds a threshold set below the withstand voltage of the high-voltage system, it is determined to be abnormal.

FIG. 3 is a flowchart showing abnormality determination processing of the first embodiment. In the drive system 1, an open fault occurs in the PN line (step S101), and the system voltage rises (step S102). At step S101, an open failure of the SMR 7 occurs. In step S102, the voltage of the smoothing capacitor 5 rises by opening the PN line.

Further, the controller 9 controls the switching elements of the inverter 3 to regenerate the inverter 3 (step S103). In step S103, the controller 9 regenerates the motor 4 and causes the PCU including the inverter 3 to regenerate.

Then, the controller 9 determines whether or not the change in the voltage value of the smoothing capacitor 5 during regeneration indicates an abnormality (step S104). In step S104, it is determined whether or not the amount of change in the voltage value of the smoothing capacitor 5 has exceeded a threshold. This step S104 is a step of performing a primary determination in the double structure abnormality determination.

As a result of the primary determination, if it is determined that the change in the voltage value of the smoothing capacitor 5 during regeneration does not indicate an abnormality (step S104: No), the control routine proceeds to step S106.

As a result of the primary determination, when it is determined that the change in the voltage value of the smoothing capacitor 5 during regeneration indicates an abnormality (step S104: Yes), the controller 9 limits the amount of regeneration (step S105). At step S105, the amount of regeneration by the motor 4 is limited. The controller 9 executes control to limit the amount of regeneration and suppress the voltage change. This step S105 is a limiting step for limiting the amount of regeneration.

The controller 9 then determines whether or not the system voltage is greater than the OVH threshold (step S106). In step S106, it is determined whether or not the capacitor voltage increased by the regenerated power in the open failure state in which the SMR 7 is open exceeds the OVH threshold. The OVH threshold is a threshold set below the withstand voltage of the high pressure system. This step S106 is a step of performing a secondary determination of the abnormality determination of the double structure, that is, a determination step of performing an abnormality determination.

As a result of the secondary determination, if the system voltage is equal to or less than the OVH threshold (step S106: No), this control routine returns to step S103.

As a result of the secondary determination, if the system voltage is greater than the OVH threshold (step S106: Yes), the controller 9 determines that an abnormality has occurred and turns off all switching elements of the inverter 3 (step S107). . In step S107, a signal for turning off all the switching elements of the inverter 3 is output from the controller 9 to the inverter 3 by detecting that the drive system 1 is abnormal. 3 is shut down.

When the processing of step S107 is performed, the controller 9 stops the vehicle and makes it impossible to travel (step S108). After the process of step S108 is executed, this control routine ends.

FIG. 4 is a time chart showing changes in capacitor voltage in the first embodiment. In the drive system 1, an open failure of the SMR 7 occurs during regeneration (time t1). Since the regenerated power is stored in the smoothing capacitor 5 after the failure occurs, the system voltage rises and the amount of change in the voltage of the smoothing capacitor 5 exceeds the threshold. Then, the controller 9 detects that the amount of change in the capacitor voltage exceeds the threshold based on the detected value from the voltage sensor 6 (time t2). As a result of the primary determination, the controller 9 limits the amount of regeneration to suppress changes in the capacitor voltage. After that, the controller 9 detects that the voltage of the smoothing capacitor 5 exceeds the OVH threshold (time t3). As a result of the secondary determination, controller 9 turns off all switching elements of inverter 3 .

As described above, according to the first embodiment, when the abnormality is determined according to the capacitor voltage, the double structure determination process is performed. time can be secured. In other words, although the voltage rises until the system is stopped due to the detection of an abnormality in the secondary judgment, the amount of regeneration is limited in advance according to the primary judgment, so the voltage rise is suppressed by that amount. be able to. Therefore, even if a voltage change due to external noise is detected, the voltage change is suppressed by limiting the amount of regeneration in the primary determination, so the system does not stop. By adopting a dual structure for abnormality determination in this way, it is possible to suppress erroneous determination even when external noise occurs.

(Second embodiment)
In the abnormality determination method according to the second embodiment, the determination according to the degree of change in the current in the drive system 1 is performed in the primary determination of the double structure abnormality determination. In addition, in the description of the second embodiment, the description of the same configuration as that of the first embodiment is omitted and the reference numerals are used.

FIG. 5 is a diagram schematically showing the configuration of the drive system of the second embodiment. The drive system 1 of the second embodiment includes a battery 2, an inverter 3, a motor 4, a smoothing capacitor 5, a voltage sensor 6, an SMR (System Main Relay) 7, a resistor 8, a controller 9, and a current sensor 10. and have.

A current sensor 10 detects the current flowing through the PN line. This current sensor 10 is connected to the positive electrode bus of the PN line and provided between the battery 2 and the SMR 7A. That is, the current sensor 10 is arranged in a circuit (low-voltage side circuit) closer to the battery 2 than the SMR 7A. A current value detected by the current sensor 10 is output to the controller 9 .

The controller 9 makes a primary determination based on information on the current of the PN line acquired from the current sensor 10 . In this primary determination, the current flowing through the PN line during regeneration (regenerative current) is determined to be abnormal when there is a discrepancy between the commanded regenerative current value (current command value) and the actual current value.

FIG. 6 is a diagram showing temporal changes in the current value of the PN line. If an open failure occurs in which the SMR 7 is in an open state, the regenerative current will not flow through the PN line between the SMR 7 and the battery 2, causing a deviation such that the actual current value decreases with respect to the current command value. Therefore, in the second embodiment, a primary determination based on the deviation amount and a secondary determination based on the capacitor voltage are performed.

FIG. 7 is a flowchart showing abnormality determination processing according to the second embodiment. Note that the processing of steps S201, S203, S205 to S208 shown in FIG. 7 is the same as the processing of steps S101, S103, S105 to S108 shown in FIG.

As shown in FIG. 7, when an open fault occurs in the PN line in step S201, the current in the PN line is interrupted (step S202). After performing the process of step S202, the control routine proceeds to step S203.

When the process of step S203 is performed, the controller 9 determines whether or not the information corresponding to the current flowing through the PN line during regeneration indicates an abnormality (step S204). In step S204, it is determined whether or not the amount of divergence between the current command value of the regenerative current and the actually measured value of the regenerative current is equal to or greater than a threshold. This step S204 is a step of performing a primary determination in the double structure abnormality determination.

As a result of the primary determination, if the information corresponding to the current flowing through the PN line during regeneration indicates an abnormality (step S204: Yes), the control routine proceeds to step S205.

If the result of the primary determination is that the information corresponding to the current flowing through the PN line during regeneration does not indicate an abnormality (step S204: No), the control routine proceeds to step S206.

FIG. 8 is a time chart showing changes in capacitor voltage in the second embodiment. In the drive system 1, an open failure of the SMR 7 occurs during regeneration (time t11). Since the regenerated electric power is stored in the smoothing capacitor 5 after the occurrence of the failure, the system voltage rises and the divergence amount of the regenerated current exceeds the threshold. Then, the controller 9 detects that the amount of divergence between the actually measured value of the regenerative current and the current command value of the regenerative current exceeds the threshold based on the detected value from the current sensor 10 (time t12). As a result of the primary determination, the controller 9 limits the amount of regeneration to suppress changes in the capacitor voltage. After that, the controller 9 detects that the voltage of the smoothing capacitor 5 exceeds the OVH threshold (time t13). As a result of the secondary determination, controller 9 turns off all switching elements of inverter 3 .

As described above, according to the second embodiment, when performing the abnormality determination of the dual structure, as the primary determination, the abnormality determination is performed according to the amount of divergence between the actual measurement value of the regenerative current and the current command value of the regenerative current. It can be carried out. Thereby, the same effects as those of the first embodiment can be obtained. Therefore, even when external noise occurs, erroneous determination can be suppressed.

Further, as a modification of the first and second embodiments, an excitation circuit is provided for outputting ON and OFF drive signals to the SMR 7 and for outputting a signal indicating the open state or short circuit state of the SMR 7 to the controller 9. good too. In this case, the controller 9 can make a primary determination according to the signal from the excitation circuit and limit the amount of regeneration.

1 drive system 2 battery 3 inverter 4 motor 5 smoothing capacitor 6 voltage sensor 7 SMR
9 controller 10 current sensor

Claims (1)

An abnormality determination method for determining an abnormality in an electric circuit during regeneration by a rotating electric machine,
a limiting step of limiting the amount of regeneration when there is a deviation between the current value of the regenerative current detected by the current sensor during regeneration and the current command value of the regenerative current;
and a determination step of determining that an abnormality has occurred in the electric circuit when the voltage value of the smoothing capacitor exceeds a predetermined value after limiting the amount of regeneration by the limiting step. Method.

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