Power converter and method for diagnosing abnormalities in a power converter

Abstract

The system detects and identifies abnormalities in the external battery and voltage detection circuit, and safely shuts down the power converter. [Solution] The power converter 2 communicates with the external controller 3 and receives power for the control board 1 from the external battery 9. The control unit of the power converter 2 receives the first external battery voltage value obtained by communication from the external controller 3 and the second external battery voltage value obtained by the voltage detection circuit 10 in the power converter 2. If 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 there is an abnormality 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 less than or equal to a fifth predetermined value, it is determined that there is an abnormality in the external battery 9.

Description

Technical Field

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

Background Art

[0002] In an electric vehicle, Patent Document 1 discloses a prior art in which the DC voltage of a main battery is converted into an AC voltage via an inverter to drive an AC motor. Further, Patent Document 1 has an abnormality diagnosis function for an auxiliary battery that serves as a power supply for a starting motor.

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

[0004] The control board 1 in FIG. 1 communicates with upper-level signals such as a motor speed command from an external controller (ECU) 3 outside the inverter 2 via a CAN communication circuit 4. In the control unit (microcomputer) 5, an operation based on the upper-level signal is performed, and an on / off command signal (gate signal) for a power semiconductor element (for example, IGBT) 6 that constitutes the inverter 2 is generated, and the power semiconductor element 6 is driven on and off via a gate drive circuit 7. Thereby, the inverter 2 composed of the power semiconductor elements 6 converts the DC voltage of the main battery 11 into a desired AC voltage and supplies it to the motor 8.

[0005] The control power supply of the control board 1 is supplied from the external battery 9. Further, the control board 1 monitors the voltage of the external battery 9 by a voltage detection circuit 10. When the voltage becomes below the threshold value in this voltage detection circuit 10, it is determined that the voltage of the external battery 9 has dropped (control power supply voltage shortage), and the inverter 2 is stopped due to a failure.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-11529 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, if the voltage detection circuit 10 in Figure 1 detects an abnormality, it is impossible to determine whether the abnormality is in the external battery 9 or the voltage detection circuit 10. Therefore, the control unit of the inverter 2 cannot accurately diagnose the control power supply voltage shortage. Furthermore, the inability to determine whether the abnormality is in the external battery 9 or the voltage detection circuit 10 also leads to increased manpower required for recovery work.

[0008] For the reasons described above, a challenge in power conversion devices is to identify and detect abnormalities in the external battery and voltage detection circuit, and to safely shut down the power conversion device. [Means for solving the problem]

[0009] The present invention was devised in view of the above-mentioned conventional problems, 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 the control unit of the power conversion device receives 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 in 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] Furthermore, in one embodiment, the control unit determines that the external battery is normal and that there is an abnormality 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 less than or equal to a second predetermined value.

[0011] Furthermore, 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] Furthermore, in another embodiment, there is a power conversion device that communicates with an external controller and receives power for the control board from an external battery, wherein the control unit of the power conversion device receives 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 less than or equal to a fifth predetermined value, the voltage detection circuit determines that it is normal and that there is an abnormality in the external battery. [Effects of the Invention]

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

[0014] [Figure 1] A schematic diagram showing a conventional power conversion device. [Figure 2] A schematic diagram showing the power conversion device of the embodiment. [Figure 3] A diagram showing the diagnostic block for the external battery and voltage detection circuit. [Modes for carrying out the invention]

[0015] The following describes in detail an embodiment of the power conversion device (inverter) according to the present invention, based on Figures 2 and 3.

[0016] [Examples] Fig. 2 shows the configuration of the power conversion device (inverter) 2 of this embodiment. The control power supply of the control board 1 is supplied from the external battery 9.

[0017] The control board 1 communicates with a higher-level signal such as a motor speed command from an external controller (ECU) 3 outside the inverter 2 via the CAN communication circuit 4. The control unit (microcomputer) 5 performs calculations based on the higher-level signal and generates an on / off command signal (gate signal) for the power semiconductor element (for example, IGBT) 6 that constitutes the inverter 2, and drives the power semiconductor element 6 to turn on and off via the gate drive circuit 7. As a result, the inverter 2 composed of the power semiconductor elements 6 converts the DC voltage of the main battery 11 into a desired AC voltage and supplies it to the motor 8.

[0018] Also, the external controller (ECU) 3 detects the voltage value of the external battery 9 as the 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 through 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 the 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. Note that the control unit that performs the abnormality diagnosis may be the microcomputer 5 as shown in Fig. 2, or a control unit in the inverter 2 provided separately from the microcomputer 5.

[0021] When an abnormality occurs in the external battery 9 itself, the first external battery voltage value becomes a value different from the normal voltage value. On the other hand, when an abnormality occurs in the voltage detection circuit 10, an abnormality occurs in the second external battery voltage value (a deviation occurs 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 equal to or greater than a predetermined value, whether the first external battery voltage value is normal, and whether the second external battery voltage value is normal.

[0023] Fig. 3 shows a block diagram of the abnormality diagnosis of the control unit. The 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. If the difference is equal to or greater than the predetermined value, it is determined that an abnormality has occurred in the voltage detection circuit 10.

[0025] In addition, when the absolute value of 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, the first external battery voltage value is within the first predetermined range (substantially normal), and the second external battery voltage value is equal to or less than the second predetermined value, the external battery 9 is normal, and it is determined that an abnormality has occurred in the voltage detection circuit 10.

[0026] In addition, when the absolute value of 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, the first external battery voltage value is equal to or less than the third predetermined value, and the second external battery voltage value is within the fourth predetermined range (substantially normal), it is determined that abnormalities have occurred in both the external battery 9 and the voltage detection circuit 10.

[0027] In addition, 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 the fifth predetermined value (and the second external battery voltage value is also equal to or less than the sixth predetermined value), it is determined that the voltage detection circuit 10 is normal and an abnormality of voltage drop has occurred in the external battery 9.

[0028] The first predetermined range, second predetermined value, third predetermined value, fourth predetermined range, fifth predetermined value, and sixth predetermined value may be the same value or they may be different values. The first predetermined range, second predetermined value, third predetermined value, fourth predetermined range, fifth predetermined value, sixth predetermined value, and predetermined value to be compared with the deviation are set appropriately considering 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 there is an abnormality, the abnormal stop unit 14 outputs an alarm and shuts down the inverter 2. Furthermore, if the normal / abnormal determination unit 13 determines that there is an abnormality, the abnormal stop unit 14 determines whether the abnormality is due to a voltage drop in the external battery 9, an abnormality in the voltage detection circuit 10, or an abnormality in both, and communicates this to the external controller (ECU) 3 via the CAN communication circuit 4 to inform the user.

[0030] Furthermore, the applications of this invention are not limited to electric vehicles. This invention can be applied to all power conversion devices that communicate with an external controller 3 and receive power for the control board 1 from an external battery 9.

[0031] As described above, according to this embodiment, in a power converter 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 converter, and to take appropriate action with the device (continue operation of the power converter or stop operation) according to the nature of the abnormality.

[0032] Furthermore, because the location of the malfunction becomes clear, the man-hours required for recovery work can be reduced.

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

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

Claims

1. A power conversion device that communicates with an external controller and receives power for the control board from an external battery, The control unit of the power converter device is The first external battery voltage value obtained by communication from the external controller, The second external battery voltage value obtained by the voltage detection circuit in the power converter is input, A power conversion device characterized in that it determines that an abnormality has occurred in the voltage detection circuit when 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.

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

3. The control unit, The power conversion device according to claim 1, characterized in that when 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, 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 power for the control board from an external battery, The control unit of the power converter device is The first external battery voltage value obtained by communication from the external controller, The second external battery voltage value obtained by the voltage detection circuit in the power converter is input, 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 less than or equal to a fifth predetermined value, the voltage detection circuit determines that the device is normal and that there is an abnormality in the external battery.

5. A method for diagnosing abnormalities in a power conversion device that communicates with an external controller and receives power for the control board from an external battery, The control unit of the power converter device is The first external battery voltage value obtained by communication from the external controller, The second external battery voltage value obtained by the voltage detection circuit in the power converter is input, A method for diagnosing abnormalities in a power converter, 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. A method for diagnosing abnormalities in a power conversion device that communicates with an external controller and receives power for the control board from an external battery, The control unit of the power converter device is The first external battery voltage value obtained by communication from the external controller, The second external battery voltage value obtained by the voltage detection circuit in the power converter is input, A method for diagnosing an abnormality in a power converter, characterized in that it determines 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 less than or equal to a fifth predetermined value.

Images