Power conversion device and method for diagnosing abnormalities in power conversion device

Abstract

It distinguishes and detects abnormalities in the external battery and voltage detection circuit, and safely shuts down the power conversion device. [Solution] A power conversion device (2) communicates with an external controller (3) and receives control power for a control board (1) from an external battery (9). A control unit of the power conversion device (2) inputs a first external battery voltage value acquired from the external controller (3) through communication and a second external battery voltage value acquired by a voltage detection circuit (10) within the power conversion device (2). If the difference between the first external battery voltage value and the second external battery voltage value is equal to or greater than a predetermined value, it is determined that an abnormality has occurred in the voltage detection circuit (10). Alternatively, if the absolute value of the difference between the first external battery voltage value and the second external battery voltage value is less than a predetermined value and the first external battery voltage value is equal to or less than a fifth predetermined value, it is determined that an abnormality has occurred in the external battery (9).

Description

[Technical Field]

[0001] The present invention relates to an external battery that supplies control power to a control board of a power conversion device (hereinafter referred to as an inverter) and a method for diagnosing a voltage detection circuit of the external battery. [Background technology]

[0002] Patent Document 1 discloses a prior art technique for driving an AC motor in an electric vehicle by converting the DC voltage of a main battery into AC voltage via an inverter. Patent Document 1 also includes a function for diagnosing an abnormality in the auxiliary battery that serves as the power source for the starting motor.

[0003] Furthermore, a configuration in which an auxiliary battery (for example, a 12V battery, hereinafter referred to as an external battery) is used as a control power supply for a control board of an inverter can be considered by applying Patent Document 1. Such a configuration is shown in FIG.

[0004] Control board 1 in Figure 1 communicates higher-level signals, such as motor rotation speed commands, from an external controller (ECU) 3 outside inverter 2 via CAN communication circuit 4. A control unit (microcomputer) 5 performs calculations based on the higher-level signals, generates on / off command signals (gate signals) for power semiconductor elements (e.g., IGBTs) 6 that make up inverter 2, and drives power semiconductor elements 6 on and off via gate drive circuit 7. In this way, inverter 2, which is made up of power semiconductor elements 6, converts the DC voltage of main battery 11 into the desired AC voltage and supplies it to motor 8.

[0005] Control power for the control board 1 is supplied from an external battery 9. Furthermore, the control board 1 monitors the voltage of the external battery 9 using a voltage detection circuit 10. If the voltage detected by this voltage detection circuit 10 falls below a threshold, it determines that the voltage of the external battery 9 has dropped (insufficient control power supply voltage) and shuts down the inverter 2 due to a fault. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-11529 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when an abnormality is detected in the voltage detection circuit 10 in Fig. 1, it is not possible to determine whether the abnormality is in the external battery 9 or in the voltage detection circuit 10, and therefore it is not possible to accurately diagnose the insufficient control power supply voltage in the control unit of the inverter 2. Furthermore, since it is not possible to determine whether the abnormality is in the external battery 9 or in the voltage detection circuit 10, there is also the problem that recovery work requires a lot of man-hours.

[0008] As described above, a problem to be solved is how to distinguish and detect abnormalities in the external battery and the voltage detection circuit in a power conversion device and safely shut down the power conversion device. [Means for solving the problem]

[0009] The present invention was devised in consideration of the above-mentioned problems in the conventional technology, and one aspect thereof is a power conversion device that communicates with an external controller and receives control power for a control board from an external battery, wherein a control unit of the power conversion device inputs a first external battery voltage value obtained by communication from the external controller and a second external battery voltage value obtained by a voltage detection circuit within the power conversion device, and determines that an abnormality has occurred in the voltage detection circuit if the absolute value of the difference between the first external battery voltage value and the second external battery voltage value is greater than or equal to a predetermined value.

[0010] In one embodiment, the control unit determines that the external battery is normal and that an abnormality has occurred in the voltage detection circuit when the first external battery voltage value is within a first predetermined range and the second external battery voltage value is equal to or lower than a second predetermined value.

[0011] In one embodiment, the control unit determines that an abnormality has occurred in both the external battery and the voltage detection circuit when the first external battery voltage value is below a third predetermined value and the second external battery voltage value is within a fourth predetermined range.

[0012] In another aspect, there is provided a power conversion device that communicates with an external controller and receives control power for a control board from an external battery, wherein a control unit of the power conversion device inputs a first external battery voltage value obtained by communication from the external controller and a second external battery voltage value obtained by a voltage detection circuit within the power conversion device, and when the absolute value of the difference between the first external battery voltage value and the second external battery voltage value is less than a predetermined value and the first external battery voltage value is equal to or less than a fifth predetermined value, the control unit determines that the voltage detection circuit is normal and that an abnormality has occurred in the external battery. [Effects of the Invention]

[0013] According to the present invention, it is possible to distinguish and detect abnormalities in the external battery and the voltage detection circuit in the power conversion device, and safely shut down the power conversion device. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram showing a conventional power conversion device. [Figure 2] 1 is a schematic diagram showing a power conversion device according to an embodiment; [Figure 3] A diagram showing the diagnostic block of the external battery and voltage detection circuit. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of the power converter (inverter) according to the present invention will be described in detail below with reference to FIGS.

[0016] [Example] 2 shows the configuration of the power conversion device (inverter) 2 of this embodiment. Control power for the control board 1 is supplied from an external battery 9.

[0017] The control board 1 communicates higher-level signals, such as motor rotation speed commands, from an external controller (ECU) 3 outside the inverter 2 via a CAN communication circuit 4. A control unit (microcomputer) 5 performs calculations based on the higher-level signals, generates on / off command signals (gate signals) for power semiconductor elements (e.g., IGBTs) 6 that make up the inverter 2, and drives the power semiconductor elements 6 on and off via a gate drive circuit 7. As a result, the inverter 2, which is made up of the power semiconductor elements 6, converts the DC voltage of the main battery 11 into the desired AC voltage and supplies it to the motor 8.

[0018] Furthermore, the external controller (ECU) 3 detects the voltage value of the external battery 9 as a first external battery voltage value. The first external battery voltage value is transmitted to the control unit 5 of the control board 1 of the inverter 2 via the CAN communication circuit 4.

[0019] Furthermore, the voltage detection circuit 10 of the control board 1 detects the voltage of the external battery 9 and transmits it to the control unit 5 as a second external battery voltage value.

[0020] The control unit 5 diagnoses abnormalities in the external battery 9 and the voltage detection circuit 10 based on the first external battery voltage value, the second external battery voltage value, and the difference between the first external battery voltage value and the second external battery voltage value. The control unit that performs the abnormality diagnosis may be the microcomputer 5 as shown in FIG. 2, or may be a control unit in the inverter 2 that is provided separately from the microcomputer 5.

[0021] If an abnormality occurs in the external battery 9 itself, the first external battery voltage value will be different from the normal voltage value. On the other hand, if an abnormality occurs in the voltage detection circuit 10, an abnormality will occur in the second external battery voltage value (a deviation will occur from the first external battery voltage value).

[0022] Therefore, the control unit 5 determines whether the difference between the first external battery voltage value and the second external battery voltage value is greater than or equal to a predetermined value, whether the first external battery voltage value is normal, and whether the second external battery voltage value is normal.

[0023] A block diagram of the abnormality diagnosis of the control unit is shown in Figure 3. A subtractor 12 subtracts the first external battery voltage value output from the external controller (ECU) 3 from the second external battery voltage value output from the voltage detection circuit 10, and outputs the difference.

[0024] The normal / abnormal determination unit 13 determines whether the absolute value of the difference output from the subtractor 12 is equal to or greater than a predetermined value, and if the difference is equal to or greater than the predetermined value, determines that an abnormality has occurred in the voltage detection circuit 10.

[0025] In addition, if the absolute value of the difference between the first external battery voltage value and the second external battery voltage value is greater than or equal to a predetermined value, the first external battery voltage value is within a first predetermined range (almost normal), and the second external battery voltage value is less than or equal to a second predetermined value, the normal / abnormal judgment unit 13 judges that the external battery 9 is normal and that an abnormality has occurred in the voltage detection circuit 10.

[0026] In addition, the normal / abnormal judgment unit 13 judges that an abnormality has occurred in both the external battery 9 and the voltage detection circuit 10 if the absolute value of the difference between the first external battery voltage value and the second external battery voltage value is greater than or equal to a predetermined value, the first external battery voltage value is less than or equal to a third predetermined value, and the second external battery voltage value is within a fourth predetermined range (almost normal).

[0027] Furthermore, if the absolute value of the difference between the first external battery voltage value and the second external battery voltage value is less than a predetermined value and the first external battery voltage value is equal to or less than a fifth predetermined value (and both the second external battery voltage value and the second external battery voltage value are equal to or less than a sixth predetermined value), the normal / abnormal judgment unit 13 judges that the voltage detection circuit 10 is normal and that a voltage drop abnormality has occurred in the external battery 9.

[0028] The first predetermined range, the second predetermined value, the third predetermined value, the fourth predetermined range, the fifth predetermined value, and the sixth predetermined value may be the same or different from each other. The first predetermined range, the second predetermined value, the third predetermined value, the fourth predetermined range, the fifth predetermined value, the sixth predetermined value, and the predetermined values ​​to be compared with the deviation are set appropriately taking into consideration the detection delay and detection variation of the voltage detection circuit 10, the CAN transmission delay of the external controller (ECU) 3, and each diagnostic condition.

[0029] If the normal / abnormal determination unit 13 determines that an abnormality has occurred, the abnormality stop unit 14 outputs an alarm and performs a fault shutdown of the inverter 2. Furthermore, if the normal / abnormality determination unit 13 determines that an abnormality has occurred, the abnormality stop unit 14 determines whether the abnormality is a voltage drop in the external battery 9, or an abnormality in the voltage detection circuit 10, or both, and communicates this to the external controller (ECU) 3 via the CAN communication circuit 4 to notify the user.

[0030] The application of the present invention is not limited to electric vehicles, but can be applied to any power conversion device that communicates with an external controller 3 and receives power from an external battery 9 for the control board 1.

[0031] As described above, according to this embodiment, in a power conversion device that uses an external battery 9 as the power source for the control board 1, it is possible to distinguish between an abnormality in the voltage drop of the external battery 9 and an abnormality in the voltage detection circuit 10 within the power conversion device, and to take measures for the device that suit the nature of the abnormality (continue / stop operation of the power conversion device).

[0032] Furthermore, since the location of the abnormality becomes clear, the labor required for recovery work can be reduced.

[0033] Although the present invention has been described in detail above only with respect to the specific examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the scope of the technical concept of the present invention, and it is natural that such modifications and variations fall within the scope of the claims. [Explanation of symbols]

[0034] 1...Control board, 2...Power conversion device (inverter), 3...External controller (ECU), 4...CAN communication circuit, 5...Control unit (microcomputer), 6...Power semiconductor device (IGBT), 7...Gate drive circuit, 8...Motor, 9...External battery, 10...Voltage detection circuit, 11...Main battery, 12...Subtractor, 13...Normal / abnormal judgment unit, 14...Abnormal stop unit

Claims

1. A power conversion device that communicates with an external controller and receives control power for a control board from an external battery, The control unit of the power conversion device a first external battery voltage value acquired from the external controller through communication; a second external battery voltage value obtained by a voltage detection circuit in the power conversion device; a first external battery voltage detection circuit that detects a voltage difference between the first external battery voltage and the second external battery voltage; a second external battery voltage detection circuit that detects a voltage difference between the first external battery voltage and the second external battery voltage;

2. The control unit 2. The power conversion device according to claim 1, wherein when the first external battery voltage value is within a first predetermined range and the second external battery voltage value is equal to or lower than a second predetermined value, it is determined that the external battery is normal and that an abnormality has occurred in the voltage detection circuit.

3. The control unit 2. The power conversion device according to claim 1, wherein when the first external battery voltage value is equal to or lower than a third predetermined value and the second external battery voltage value is within a fourth predetermined range, it is determined that an abnormality has occurred in both the external battery and the voltage detection circuit.

4. A power conversion device that communicates with an external controller and receives control power for a control board from an external battery, The control unit of the power conversion device a first external battery voltage value acquired from the external controller through communication; a second external battery voltage value obtained by a voltage detection circuit in the power conversion device; A power conversion device characterized in that, when the absolute value of the difference between the first external battery voltage value and the second external battery voltage value is less than a predetermined value and the first external battery voltage value is equal to or less than a fifth predetermined value, it is determined that the voltage detection circuit is normal and that an abnormality has occurred in the external battery.

5. 1. A method for diagnosing an abnormality in a power conversion device that communicates with an external controller and receives control power for a control board from an external battery, comprising: The control unit of the power conversion device a first external battery voltage value acquired from the external controller through communication; a second external battery voltage value obtained by a voltage detection circuit in the power conversion device; An abnormality diagnosis method for a power conversion device, characterized in that if the absolute value of the difference between the first external battery voltage value and the second external battery voltage value is greater than or equal to a predetermined value, it is determined that an abnormality has occurred in the voltage detection circuit.

6. 1. A method for diagnosing an abnormality in a power conversion device that communicates with an external controller and receives control power for a control board from an external battery, comprising: The control unit of the power conversion device a first external battery voltage value acquired from the external controller through communication; a second external battery voltage value obtained by a voltage detection circuit in the power conversion device; An abnormality diagnosis method for a power conversion device, characterized in that it is determined that an abnormality has occurred in the external battery when the absolute value of the difference between the first external battery voltage value and the second external battery voltage value is less than a predetermined value and the first external battery voltage value is equal to or less than a fifth predetermined value.

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