controller

Abstract

To provide a controller capable of detecting abnormality of a current sensor.SOLUTION: A controller 1 comprises an ECU 70. The ECU 70 calculates a difference between a torque variation amount according to temperature of a current sensor 60 detected by a temperature sensor 50, and another torque variation amount according to a current value detected by the current sensor 60 to increase a supplied current to a motor generator 40 from an inverter 30 for a prescribed period if the difference is a threshold value or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a control device. [Background technology]

[0002] Patent Document 1 discloses a technique for suppressing voltage fluctuations in a smoothing capacitor and torque fluctuations in a motor. This technique controls an inverter based on the detection results of a current sensor that detects the current of each phase of the motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-129954 Summary of the Invention [Problem to be solved by the invention]

[0004] However, current sensors generate errors in their detection results due to temperature changes. For this reason, in the above-mentioned Patent Document 1, if an error occurs due to temperature changes in the current sensor, a difference occurs between the amount of torque fluctuation that is actually desired to be output and the amount of torque fluctuation fed back from the current sensor, and as this error increases, the torque fluctuates, which can cause the vehicle to vibrate.

[0005] In addition, in the past, torque fluctuations occurred when the current sensor failed, but the threshold value for detecting abnormalities set for the current sensor was set taking into account variations other than temperature, so it was possible that an abnormality could not be detected from torque fluctuations.

[0006] The present disclosure has been made in view of the above, and aims to provide a control device that can detect an abnormality in a current sensor. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the objectives, the control device of the present disclosure is a control device that controls a drive device including a battery, a three-phase AC electric motor, a power conversion device that performs power conversion between the battery and the electric motor to convert DC power to AC power to drive the electric motor, a current sensor that detects the current value of a power line provided between the electric motor and the power conversion device, and a temperature sensor that detects the temperature of the current sensor, and is equipped with a processor, wherein the processor calculates the difference between the torque fluctuation amount corresponding to the temperature of the current sensor detected by the temperature sensor and the torque fluctuation amount corresponding to the current value detected by the current sensor, and if the difference is equal to or greater than a threshold value, increases the current supplied to the electric motor from the power conversion device for a predetermined period of time. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to advantageously detect an abnormality in a current sensor. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing the overall configuration of a control device according to an embodiment. [Figure 2] FIG. 2 is a flowchart showing an outline of the process executed by the control device according to one embodiment. [Figure 3] FIG. 3 is a diagram illustrating the relationship between torque fluctuation and current sensor error according to one embodiment. [Figure 4] FIG. 4 is a diagram showing the relationship between torque and current value at an operating point on the optimum line of the motor generator according to one embodiment. [Figure 5] FIG. 5 is a diagram illustrating the operating points of the motor generator as a motor in an HEV, the engine, and the generator. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an electric motor control device according to an embodiment of the present disclosure will be described with reference to the drawings. Note that the components in the following embodiments include those that are easily replaceable by those skilled in the art, or those that are substantially identical. Furthermore, the drawings referred to in the following description merely show a schematic representation of the shape, size, and positional relationship to the extent that the contents of the present disclosure can be understood. In other words, the present disclosure is not limited to only the shape, size, and positional relationship illustrated in each drawing.

[0011] [Overall configuration of the control device] Fig. 1 is a diagram showing the overall configuration of a control device according to one embodiment. The control device 1 shown in Fig. 1 can be mounted on vehicles such as HEVs (Hybrid Electric Vehicles), PHEVs (Plug-in Hybrid Electric Vehicles), EVs (Electric Vehicles), and FCEVs (Fuel Cell Electric Vehicles), and an electric motor is used as a power source for the vehicle.

[0012] The control device 1 includes a battery 10, a converter unit 20, an inverter 30 as a power conversion device, a motor generator 40 that functions as a drive source and an electric motor, a temperature sensor 50, a current sensor 60, and an ECU (Electronic Control Unit) 70.

[0013] Battery 10 is configured as a secondary battery such as a nickel-metal hydride battery or a lithium-ion battery. Battery 10 may be a battery having a liquid electrolyte between the positive and negative electrodes, or may be an all-solid-state battery having a solid electrolyte. Battery 10 is configured as a battery pack in which a plurality of unit cells (battery cells) such as lithium-ion batteries are electrically connected in series.

[0014] Converter unit 20 is electrically connected to battery 10 via power lines PL and NL, and the other end is electrically connected to inverter 30. Under the control of ECU 70, converter unit 20 boosts the DC current output from battery 10 and outputs it to inverter 30. Converter unit 20 boosts the DC current output from battery 10 and outputs it to inverter 30 in accordance with a control signal from ECU 70. Converter unit 20 is configured using, for example, a boost DC-DC converter.

[0015] Under the control of the ECU 70, the inverter 30 converts DC power input from the battery 10 via the converter unit 20 into AC power and outputs the AC power to the motor generator 40 to drive the motor generator 40. Also, under the control of the ECU 70, the inverter 30 converts AC power generated by the motor generator 40 into DC power and outputs the DC power to the battery 10. In other words, the battery 10 can charge power between the battery 10 and the motor generator 40 via the inverter 30.

[0016] Inverter 30 includes a U-phase arm 31, a V-phase arm 32, and a W-phase arm 33. U-phase arm 31, V-phase arm 32, and W-phase arm 33 are electrically connected in parallel between power lines PL and NL. U-phase arm 31 has switching element Q1 and switching element Q2 connected in series. V-phase arm 32 has switching element Q3 and switching element Q4 connected in series. W-phase arm 33 has switching element Q5 and switching element Q6 connected in series. Diodes D1 to D6 are electrically connected in anti-parallel between the collector and emitter of each of switching elements Q1 to Q6.

[0017] The midpoints of U-phase arm 31, V-phase arm 32, and W-phase arm 33 are electrically connected to the respective phase ends of the respective phase coils of motor generator 40. The midpoints of switching element Q1 and switching element Q2 are electrically connected to one end of the U-phase coil of motor generator 40. The midpoints of switching element Q3 and switching element Q4 are electrically connected to one end of the V-phase coil of motor generator 40. The midpoints of switching element Q5 and switching element Q6 are electrically connected to one end of the W-phase coil of motor generator 40. The other ends of the three coils of U-phase, V-phase, and W-phase of motor generator 40 are commonly connected to a neutral point.

[0018] The inverter 30 configured in this manner converts DC power into AC power in accordance with a control signal from the ECU 70 to drive the motor generator 40 .

[0019] The motor generator 40 is, for example, a drive motor that generates torque for driving the drive wheels of a vehicle. The motor generator 40 is a three-phase AC synchronous motor, and is assumed to be, for example, an interior permanent magnet (IPM) dynamic motor with a permanent magnet embedded in the rotor.

[0020] The temperature sensor 50 detects the temperature of the current sensor 60 and outputs the detection result to the ECU 70 .

[0021] Current sensor 60 detects the current of any phase in the three-phase current (motor current) flowing through motor generator 40, and outputs the detection result to ECU 70. In one embodiment, current sensor 60 is provided only in the V phase, but the present invention is not limited to this and current sensor 60 may be provided in each of the U phase and W phase, or in either the U phase or the W phase.

[0022] The ECU 70 is implemented using a processor having hardware such as an FPGA (Field-Programmable Gate Array) or a CPU (Central Processing Unit), and a memory serving as a temporary storage area used by the processor, storing software (programs) capable of executing applications (hereinafter simply referred to as "apps"). The ECU 70 calculates the difference between the torque fluctuation amount corresponding to the temperature of the current sensor 60 detected by the temperature sensor 50 and the torque fluctuation amount corresponding to the current value detected by the current sensor 60, and if this difference is equal to or greater than a threshold, increases the current supplied from the inverter 30 to the motor generator 40 for a predetermined period. In one embodiment, the ECU 70 functions as the processor.

[0023] [Processing by the control device] Next, a description will be given of the processing performed by the control device 1. Fig. 2 is a flowchart showing an outline of the processing performed by the control device 1.

[0024] As shown in FIG. 2, first, the ECU 70 acquires the temperature of the current sensor 60 measured by the temperature sensor 50 (step S101), and calculates the torque fluctuation that may occur from the temperature measured by the temperature sensor 50 (step S102).

[0025] Next, ECU 70 determines the current torque fluctuation in motor generator 40 from the deviation between the current torque command for motor generator 40 and the torque estimated from the sensor value detected by current sensor 60 (step S103).

[0026] Thereafter, the ECU 70 determines whether the current torque fluctuation amount can be caused by temperature (step S104), and if it is determined that the current torque fluctuation amount can be caused by temperature (step S104: Yes), the control device 1 proceeds to step S105, which will be described later. On the other hand, if it is determined that the current torque fluctuation amount cannot be caused by temperature (step S104: No), the control device 1 proceeds to step S106, which will be described later.

[0027] In step S105, the ECU 70 suppresses the fluctuation by lowering the temperature of the motor generator 40. After step S105, the control device 1 ends this process.

[0028] In step S106, the ECU 70 increases the value of the current supplied to the motor generator 40. In this case, there is a possibility that the current sensor 60 is malfunctioning, and the ECU 70 intentionally increases the current value to increase the value of the current supplied to the motor generator 40 so as to deviate from the optimum operating point.

[0029] FIG. 3 shows the relationship between torque fluctuation and current sensor error. FIG. 4 shows the relationship between torque and current value at the operating point of the optimal line for motor generator 40. FIG. 5 is a diagram illustrating the operating points of motor generator 40 as a motor in an HEV, the engine, and the generator. In FIG. 3, the horizontal axis represents current sensor error, the vertical axis represents torque fluctuation, and line L1 represents the relationship between current sensor error and torque fluctuation. Furthermore, in FIG. 3, point P1 represents the error amount expected due to temperature variation, and point P2 represents the error amount detected when an abnormality occurs in current sensor 60. Furthermore, in FIG. 4, the horizontal axis represents electrical advance angle [edeg], the vertical axis represents torque [N·m], and curve L10 represents the optimal advance angle at the operating point of the optimal torque.

[0030] As shown in region R1 in Figures 3(a) and 3(b), the ECU 70 can detect an error caused by the current sensor 60 in region R1 even when the ECU 70 increases the current value output to the motor generator 40 by controlling the converter unit 20 and the inverter 30. Furthermore, as shown in Figure 4, the ECU 70 sets an optimal operating point line (see curve L10) in normal control, taking into consideration the efficiency, loss, etc. of the motor generator 40. Therefore, as shown by arrow K1 in Figure 4, the ECU 70 can increase the current value to the motor generator 40 with the same torque, even when the current value deviates from the optimal operating point line.

[0031] In this way, the ECU 70 detects that the current sensor 60 may be malfunctioning and deliberately increases the current value supplied to the motor generator 40 to deviate from the optimal operating point. The ECU 70 may also increase the ripple current by changing the carrier frequency supplied to the motor generator 40. As shown in FIG. 5, in an HEV, the operating point of the motor generator 40, which is the traction motor, can be fixed while the operating points of the generator motor and engine can be changed. Therefore, the ECU 70 can detect an abnormality in the current sensor 60 by increasing the current value by changing the operating points of the generator motor and engine while keeping the operating point of the motor generator 40, which is the traction motor, fixed.

[0032] Returning to FIG. 2, the description of step S107 and subsequent steps will be continued. In step S107, the ECU 70 determines whether the detection result detected by the current sensor 60 is equal to or greater than a threshold value. If the ECU 70 determines that the detection result detected by the current sensor 60 is equal to or greater than the threshold value (step S107: Yes), the control device 1 proceeds to step S108, which will be described later. On the other hand, if the ECU 70 determines that the detection result detected by the current sensor 60 is not equal to or greater than the threshold value (step S107: No), the control device 1 proceeds to step S109, which will be described later.

[0033] In step S108, the ECU 70 determines that an abnormality has occurred in the current sensor 60. After step S108, the control device 1 ends this process.

[0034] In step S109, the ECU 70 determines whether or not an instruction to change the operating point has been issued to the motor generator 40. If it is determined that the ECU 70 has issued an instruction to change the operating point to the motor generator 40 (step S109: Yes), the control device 1 returns to step S101. On the other hand, if it is determined that the ECU 70 has not issued an instruction to change the operating point to the motor generator 40 (step S109: No), the control device 1 ends this process.

[0035] According to the embodiment described above, the current value supplied to the motor generator 40 is increased so as to deviate from the optimal operating point, and if it is determined that the detection result detected by the current sensor 60 is above the threshold value, it can be determined that an abnormality has occurred in the current sensor 60, so that a failure of the current sensor 60 can be reliably detected.

[0036] Further advantages and modifications will readily occur to those skilled in the art. The invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

[0037] Although some of the embodiments of the present application have been described in detail above with reference to the drawings, these are merely examples, and the present invention can be implemented in other forms that have undergone various modifications and improvements based on the knowledge of those skilled in the art, including the aspects described in the disclosure of the present invention. [Explanation of symbols]

[0038] 1. Control device 10 Battery 20 Converter section 30 inverters 40 Motor generator 50 Temperature Sensor 60 Current Sensor 70 ECU NL,PL power line

Claims

[Claim 1] A battery, A three-phase AC motor, a power conversion device that performs power conversion between the battery and the electric motor to convert DC power into AC power to drive the electric motor; a current sensor for detecting a current value of a power line provided between the electric motor and the power conversion device; a temperature sensor for detecting the temperature of the current sensor; Equipped with A control device that controls a drive device, a processor; The processor: calculating a difference between a torque fluctuation amount corresponding to the temperature of the current sensor detected by the temperature sensor and a torque fluctuation amount corresponding to the current value detected by the current sensor; If the difference is equal to or greater than a threshold value, the current supplied from the power conversion device to the electric motor is increased for a predetermined period. Control device.

Images