Driving device

Abstract

To detect a welding of a relay.SOLUTION: A drive device includes: a motor; an inverter that drives the motor; a power storage device; a relay that connects and disconnects a first power line to which the inverter is connected to the power storage device; a fuel battery; a boost converter provided between a second power line to which the fuel battery is connected and the first power line; a leakage detection device that is connected to a negative terminal of the power storage device and oscillates a signal of a predetermined frequency; and a control device. After executing a relay opening control, the control device controls the boost converter so that a pulsation of a frequency that is a natural number multiple of the predetermined frequency is superimposed on a voltage or a current of the first power line, and determines that the relay is welded when the pulsation width of a detection signal detected by the electric leakage detection device at that time is larger than the predetermined pulsation width.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Conventionally, as this type of technology, a drive device has been proposed that includes a power storage device, an inverter that drives a motor using power from the power storage device, a charging device for charging the power storage device using power from an external power source, the charging device including a pair of relays that open and close the power supply path from the external power source to the power storage device so as not to interrupt the path between the power storage device and the inverter, and a control device that detects voltages on the external power source sides of the pair of relays while controlling the pair of relays to an open state during switching operation of the inverter, and determines whether the pair of relays are welded based on the detection result (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5421000 Summary of the Invention [Problem to be solved by the invention]

[0004] Detecting relay welding is also an issue in a drive device that includes a motor, an inverter that drives the motor, a power storage device, a relay that connects and disconnects the power storage device to a first power line connected to the inverter, a leakage detection device that is connected to the negative terminal of the power storage device and oscillates a signal at a predetermined frequency, a fuel cell, and a boost converter that is provided between the first power line and a second power line connected to the fuel cell. When the output voltage of the fuel cell is relatively high, the voltage of the first power line is also maintained relatively high. Even if the motor consumes power after controlling the relay to open, the voltage of the first power line may not decrease regardless of whether the relay opened normally. Therefore, there is a need for a method that can detect relay welding even in such cases. The drive device disclosed herein primarily aims to be able to detect relay welding. [Means for solving the problem]

[0005] The drive device of the present disclosure employs the following measures to achieve the above-mentioned primary object: The drive device of the present disclosure includes a motor, an inverter that drives the motor, a power storage device, a relay that connects and disconnects the power storage device to a first power line connected to the inverter, a fuel cell, a boost converter that is provided between the first power line and a second power line connected to the fuel cell, a ground fault detection device that is connected to a negative terminal of the power storage device and oscillates a signal of a predetermined frequency, and a control device, wherein the control device controls the boost converter after executing control to open the relay so that a pulsation of a frequency that is a natural number multiple of the predetermined frequency is superimposed on the voltage or current of the first power line, and determines that the relay is welded if the pulsation width of the detection signal detected by the ground fault detection device at that time is larger than the predetermined pulsation width.

[0006] In the drive device of the present disclosure, after executing control to open the relay, the boost converter is controlled so that pulsation of a frequency that is a natural number multiple of a predetermined frequency (the frequency of the oscillation signal of the leakage detection device) is superimposed on the voltage or current of the first power line, and if the pulsation amplitude of the detection signal detected by the leakage detection device at that time is larger than the predetermined pulsation amplitude, it is determined that the relay is welded.By controlling the boost converter as described above, the pulsation amplitude of the detection signal becomes larger when the relay is welded, making it possible to detect whether the relay is welded. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram of a drive device 20 according to an embodiment. [Figure 2] 10 is a flowchart illustrating an example of a processing routine. [Figure 3] 10 is an explanatory diagram showing an example of the state of the voltage FVH of the power line 43 and the detected voltage Vo of the earth leakage detector 48. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic diagram of a drive device 20 according to the embodiment. As shown in the figure, the drive device 20 is mounted on a fuel cell vehicle and includes a motor 22, an inverter 24, a battery 26 as a power storage device, a system main relay SMR, a fuel cell 34, a boost converter 40, a leakage detection device 48, and an electronic control unit 50.

[0009] The motor 22 is configured as, for example, a synchronous generator motor, and a rotor of the motor 22 is connected to a drive shaft coupled to drive wheels. The inverter 24 has multiple switching elements and drives the motor 22 to rotate by switching the multiple switching elements. The inverter 24 is connected to power lines 30 (positive line 30a and negative line 30b). A capacitor 32 is connected to the positive line 30a and the negative line 30b. The battery 26 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery. The system main relay SMR includes a positive electrode relay SMRB and a negative electrode relay SMRG. The positive electrode relay SMRB connects and disconnects the positive electrode line 30a to and from the positive terminal of the battery 26. The negative electrode relay SMRG connects and disconnects the negative electrode line 30b to and from the negative terminal of the battery 26. The fuel cell 34 generates electricity through an electrochemical reaction between hydrogen as a fuel gas supplied from a high-pressure hydrogen tank and circulated by a fuel pump (circulation pump) and oxygen in the air supplied by an oxygen pump (air compressor) and humidified by a humidifier that humidifies the air with water vapor in the exhaust. The fuel cell 34 is connected to power lines 36 (positive electrode line 36a and negative electrode line 36b).

[0010] The boost converter 40 includes a power line 41 (positive line 41a and negative line 41b), a capacitor 42, a power line 43 (positive line 43a and negative line 43b), a capacitor 44, a diode D1, a transistor T1 serving as a switching element, and a reactor L1. The positive line 41a and the negative line 41b are connected to the positive line 36a and the negative line 36b, respectively. The capacitor 42 is connected to the positive line 41a and the negative line 41b. The positive line 43a and the negative line 43b are connected to the positive line 30a and the negative line 30b, respectively. The capacitor 44 is connected to the positive line 43a and the negative line 43b. The cathode of the diode D1 is connected to the positive line 43a. The transistor T1 is connected to the anode of the diode D1 and is also connected to the negative lines 41b and 43b. Reactor L1 is connected to the anode of diode D1 and transistor T1, and is also connected to positive line 41a. Boost converter 40 can boost the power of power line 41 (power line 36) and supply it to power line 43 (power line 30) by controlling the switching of transistor T1.

[0011] The leakage detection device 48 includes an oscillation power supply, a detection resistor element, a coupling capacitor, a voltage sensor, and an insulation reduction unit. The oscillation power supply, the detection resistor element, and the coupling capacitor are connected in series, in this order, between the ground (vehicle body) and the negative terminal of the battery 26. The oscillation power supply oscillates a signal (sine wave signal or pulse signal) of frequency f1 (e.g., 2.5 Hz). The voltage detector outputs the voltage at a connection point Cd between the detection resistor element and the coupling capacitor as a detection voltage Vo to the electronic control unit 50. The insulation reduction unit is configured to be able to reduce the insulation resistance to ground of the electrical connection portion, which is a portion electrically connected to the negative terminal of the battery 26. When the system main relay SMR is open, the electrical connection portion corresponds to a first portion that is a portion closer to the battery 26 than the system main relay SMR. When the system main relay SMR is closed, the electrical connection portion corresponds to both the first portion and a second portion that is a portion closer to the power line 30 than the system main relay SMR. The electronic control unit 50 basically does not activate the insulation reduction section, but uses the detected voltage Vo from the voltage detector to determine whether the insulation resistance of the electrical connection to the ground has decreased (there is a risk of electrical leakage).

[0012] The electronic control unit 50 includes a microcomputer having a CPU, ROM, RAM, flash memory, and input / output ports. The electronic control unit 50 receives signals from various sensors via the input ports. For example, the electronic control unit 50 receives the rotational position θm of the rotor of the motor 22 from a rotational position sensor, the voltage Vb of the battery 26 from a voltage sensor 26v, the current Ib of the battery 26 from a current sensor 26i, and the voltage VH of the power line 30 (capacitor 32) from a voltage sensor 32v. The electronic control unit 50 also receives the output voltage Vfc of the fuel cell 34 from a voltage sensor 34v, the voltage FVL of the power line 41 (capacitor 42) from a voltage sensor 42v, the voltage FVH of the power line 43 (capacitor 44) from a voltage sensor 44v, and the detected voltage Vo from a leakage current detector 48. The electronic control unit 50 also receives inputs of a power signal from a power switch, the operating position (shift position) of the shift lever from a shift position sensor, the depression amount of the accelerator pedal (accelerator opening) from an accelerator sensor, the depression amount of the brake pedal (brake pedal position) from a brake sensor, and the vehicle speed from a vehicle speed sensor. The electronic control unit 50 outputs various control signals via output ports. For example, the electronic control unit 50 outputs a control signal to the inverter 24, a control signal to the system main relay SMR (positive relay SMRB and negative relay SMRG), a control signal to the fuel cell 34, and a control signal to the boost converter 40 (transistor T1). The electronic control unit 50 calculates the rotation speed Nm of the motor 22 based on the rotational position θm of the rotor of the motor 22, and calculates the state of charge (SOC) of the battery 26 based on the integrated value of the current Ib of the battery 26.

[0013] Next, the operation of the drive device 20 of this embodiment configured as described above will be described. Figure 2 is a flowchart showing an example of a processing routine executed by the electronic control unit 50. This routine is executed, for example, when the power switch is turned off and an instruction to stop the vehicle system is issued. When an instruction to stop the vehicle system is issued, before starting this routine, the fuel cell 34 is stopped from operating and a voltage reduction process is executed to quickly reduce the output voltage Vfc of the fuel cell 34 (the voltage FVL of the power line 41).

[0014] 2 is executed, the electronic control unit 50 first executes control to open the positive electrode relay SMRB and the negative electrode relay SMRG (step S100). Next, it is determined whether the voltage VH of the power line 30 is less than a threshold value VHref (step S110). Here, the threshold value VHref is a threshold value for determining whether the voltage VH is sufficiently low, and is, for example, approximately several tens of volts. When it is determined that the voltage VH of the power line 30 is less than the threshold value VHref, it is determined that the system main relay SMR is normal (step S120), and this routine is terminated.

[0015] If it is determined in step S110 that the voltage VH of the power line 30 is equal to or greater than the threshold VHref, it is then determined whether the voltage FVL of the power line 41 is less than the threshold FVLref (step S130). Here, the threshold FVLref is a threshold for determining whether the voltage FVL is sufficiently low, and is, for example, approximately several tens of volts. If it is determined that the voltage FVL of the power line 41 is less than the threshold FVLref, a discharge process is executed (step S140). Here, the discharge process is a process for controlling the inverter 24 so that only the d-axis current flows through the motor 22. Since the case where the voltage FVL is sufficiently low is considered, when the positive electrode relay SMRB and / or the negative electrode relay SMRG are normally open, the voltage VH of the power line 30 drops.

[0016] Next, the amount of decrease ΔVH in voltage VH before and after the discharge process is calculated using voltage VH on power line 30 from voltage sensor 32v, and it is determined whether the calculated amount of decrease ΔVH is equal to or greater than a threshold value ΔVHref (step S150). If it is determined that the amount of decrease ΔVH is equal to or greater than the threshold value ΔVHref, the system main relay SMR is determined to be normal (step S160), and this routine is terminated.

[0017] If it is determined in step S150 that the decrease ΔVH is less than the threshold value ΔVHref, it is determined whether the integrated value Sib of the current Ib of the battery 26 during the discharge process is equal to or greater than the threshold value Sibref (step S170). Here, the threshold value Sibref is a threshold value for determining whether a certain amount of current Ib has flowed during the discharge process. If it is determined that the integrated value Sib is equal to or greater than the threshold value Sibref, it is determined whether the positive electrode relay SMRB and the negative electrode relay SMRG are welded (step S210), and this routine ends. On the other hand, if it is determined that the integrated value Sib is less than the threshold value Sibref, it is determined that there is an abnormality other than welding of the positive electrode relay SMRB and the negative electrode relay SMRG, and it is determined that there is an abnormality in the voltage sensor 32v (step S220), and this routine ends. The latter is based on the reason that it is expected that the decrease ΔVH will be large when the integrated value Sib is small.

[0018] When it is determined in step S130 that the voltage FVL of the power line 41 is equal to or greater than the threshold value FVLref, the electric leakage detection device 48 executes a self-circuit check process and executes voltage pulsation control for the boost converter 40 (steps S180 and S190). Here, the self-circuit check process of the electric leakage detection device 48 activates an insulation lowering unit to lower the insulation resistance of the electrical connection to the ground (making the detected voltage Vo more susceptible to noise). In the voltage pulsation control, the boost converter 40 is controlled so that pulsation at a frequency that is a natural number multiple of the frequency f1 of the oscillation signal of the oscillating power supply of the electric leakage detection device 48 is superimposed on the voltage FVH of the power line 43 (the voltage VH of the power line 30), the voltage FVL of the power line 41, or the current of these power lines is superimposed. For example, the boost converter 40 is controlled so that the voltage FVH pulsates at a frequency that is approximately several tens of volts higher than the target voltage and several to ten times higher than the frequency f1.

[0019] Then, during voltage pulsation control, it is determined whether the pulsation width (peak value) Wp of the voltage Vo detected by the voltage detector of the leakage detection device 48 is equal to or greater than a threshold value Wpref (step S200). Here, the threshold value Wpref is a threshold value for determining whether the pulsation width Wp is relatively large. If it is determined that the pulsation width Wp is equal to or greater than the threshold value Wpref, it is determined whether the positive electrode relay SMRB and the negative electrode relay SMRG are welded (step S210), and the routine ends. On the other hand, if it is determined that the pulsation width Wp is less than the threshold value Wpref, it is determined that there is an abnormality other than welding of the positive electrode relay SMRB and the negative electrode relay SMRG, and it is determined that there is an abnormality in the voltage sensor 32v (step S220), and the routine ends.

[0020] 3 is an explanatory diagram showing an example of the state of the voltage FVH of the power line 43 and the detected voltage Vo of the earth leakage detection device 48 when voltage pulsation control is being performed with the system main relay SMR closed. When the positive electrode relay SMRB and the negative electrode relay SMRG are welded, the battery 26 is connected to a portion closer to the power line 30 than the system main relay SMR. Therefore, as shown in FIG. 3, the detected voltage Vo pulsates significantly due to the influence of pulsation (noise) in the voltage FVH of the power line 43 (the voltage VH of the power line 30) caused by the voltage pulsation control. Therefore, when the pulsation width Wp of the detected voltage Vo is equal to or greater than the threshold value Wpref, it is possible to detect the welding of the positive electrode relay SMRB and the negative electrode relay SMRG.

[0021] In the drive device 20 of the embodiment described above, after executing control to open the system main relay SMR (positive electrode relay SMRB and negative electrode relay SMRG), when voltage VH is equal to or greater than threshold value VHref and voltage FVL is equal to or greater than threshold value FVLref, boost converter 40 is controlled so that pulsation of a frequency that is a natural number multiple of frequency f1 of the oscillation signal of the oscillation power supply of earth leakage detection device 48 is superimposed on voltage FVH of power line 43 (voltage VH of power line 30), voltage FVL of power line 41, or their currents. Then, when the pulsation width (peak value) Wp of voltage Vo detected by the voltage detector of earth leakage detection device 48 at that time is equal to or greater than threshold value Wpref, welding of positive electrode relay SMRB and negative electrode relay SMRG is determined. In this manner, welding of positive electrode relay SMRB and negative electrode relay SMRG can be detected.

[0022] In the above-described embodiment, when the voltage FVL of the power line 41 is equal to or greater than the threshold value FVLref in step S130 of the processing routine of FIG. 2, the self-circuit check processing of the leakage current detection device 48 and the voltage pulsation control for the boost converter 40 are executed, but the self-circuit check processing of the leakage current detection device 48 may be omitted.

[0023] The correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problem" section will be described below. In the embodiment, the motor 22 corresponds to the "motor," the inverter 24 corresponds to the "inverter," the battery 26 corresponds to the "power storage device," the system main relay SMR corresponds to the "relay," the fuel cell 34 corresponds to the "fuel cell," the boost converter 40 corresponds to the "boost converter," the earth leakage detection device 48 corresponds to the "earth leakage detection device," and the electronic control unit 50 corresponds to the "control device."

[0024] The above describes the forms for implementing the present disclosure using embodiments, but the present disclosure is not limited to these embodiments in any way, and it goes without saying that the present disclosure can be implemented in various forms within the scope that does not deviate from the gist of the present disclosure. [Industrial Applicability]

[0025] The present disclosure is applicable to industries such as the drive device manufacturing industry. [Explanation of symbols]

[0026] 20 drive unit, 22 motor, 24 inverter, 26 battery, 26i current sensor, 26v, 32v, 34v, 42v, 44v voltage sensors, 30, 36, 41, 43 power lines, 30a, 36a, 41a, 43a positive lines, 30b, 36v, 41b, 43b negative lines, 32, 42, 44 capacitors, 34 fuel cell, 40 boost converter, 48 leakage current detection device, 50 electronic control unit, D1 diode, L1 reactor, T1 transistor.

Claims

[Claim 1] A drive device comprising: a motor; an inverter for driving the motor; a power storage device; a relay for connecting and disconnecting a first power line to which the inverter is connected and the power storage device; a fuel cell; a boost converter provided between the first power line and a second power line to which the fuel cell is connected; a leakage detection device connected to a negative terminal of the power storage device and oscillating a signal of a predetermined frequency; and a control device, After executing the control to open the relay, the control device controls the boost converter so that pulsation having a frequency that is a natural number multiple of the predetermined frequency is superimposed on the voltage or current of the first power line, and if the pulsation width of the detection signal detected by the leakage detection device at that time is larger than the predetermined pulsation width, it determines that the relay is welded. Drive unit.

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