JP2009183134A - Power unit and welding determining method of relay - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power unit and a welding determining method of a relay, for running without battery while a power supply is surely cut off. <P>SOLUTION: An HV controller 160, when receiving a fault of a battery, sends an SMR interruption command and a VL constant request to an MGECU140. A converter controller 144 forms a signal SE for turning off a system main relay according to the SMR interruption command. An SMR welding determining portion 162 changes a voltage command value VL*, which is a target value when a converter drops a motor operation voltage in a VL constant control, to a lower pressure side and a higher pressure side than the variable range of a DC voltage VL acquired in advance when the battery is connected. The SMR welding determining portion 162 determines welding of the system main relay, based on followability with respect to the voltage command value VL* of the DC voltage VL. The HV controller 160 drives a vehicle without battery, when the system main relay is normal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power supply device, and more particularly to a power supply device mounted on a vehicle using an electric motor as a driving force source and a relay welding determination method in the power supply device.

  Recently, as an environment-friendly vehicle, a hybrid vehicle incorporating a motor (motor) in a drive device has attracted a great deal of attention and has been partially put into practical use. This hybrid vehicle is equipped with a power source consisting of a secondary battery, an electric double layer capacitor, etc. to supply electric power to the motor that is the driving force source or to convert kinetic energy into electric energy during regenerative braking. Has been.

  In such a hybrid vehicle, when an abnormality occurs in the power source such as a failure of the power source or a charging circuit for charging the power source, the power source and the power line are connected for the purpose of prohibiting discharging from the power source and charging to the power source. The power supply is cut off by opening the relay for this purpose. And what is called battery-less driving | running | working which drives a vehicle, without charging / discharging a power supply is performed.

  For example, in Japanese Patent Application Laid-Open No. 2003-204606 (Patent Document 1), when an abnormality occurs in a battery, the system main relay for connecting / cutting off a high-voltage power supply from the battery is turned off to perform battery-less traveling. A hybrid vehicle for performing is disclosed.

Specifically, the hybrid vehicle has an engine, a planetary gear having a carrier connected to the crankshaft of the engine and a ring gear connected to the axle, a generator connected to the sun gear of the planetary gear, and power to the axle. An electric motor for output. When a battery failure is detected, the system main relay is turned off, and the counter electromotive force generated by the rotation of the generator with the rotation of the engine is supplied to the motor, thereby enabling battery-less traveling. Yes.
JP 2003-204606 A JP 2005-261040 A

  However, in the hybrid vehicle disclosed in Japanese Patent Application Laid-Open No. 2003-204606, when the system main relay is welded due to excessive current passing through the system main relay due to a battery failure or the like, the system main Even if the relay is turned off, the energized state continues. Therefore, power can be output without charging / discharging the battery in terms of control, but depending on the vehicle state, charging / discharging may occur in the battery.

  Therefore, in order to avoid charging / discharging of the battery, it is necessary to perform battery-less traveling in a state in which it is guaranteed that the system main relay is securely cut off. However, Japanese Patent Laid-Open No. 2003-204606 described above does not disclose means for solving such a problem.

  Therefore, the present invention has been made to solve such a problem, and an object of the present invention is to provide a power supply apparatus that can perform battery-less running in a state where the power supply is reliably cut off.

  Another object of the present invention is to provide a relay welding determination method that can perform battery-less traveling in a state where the power source is reliably cut off.

  A power supply apparatus according to an aspect of the present invention includes a power supply provided to be able to supply a DC voltage to first and second power supply lines, and a relay for connecting and disconnecting between the power supply and the first and second power supply lines. , A voltage converter that performs voltage conversion between the first and second power supply lines and the electric load according to the voltage command value, and when a power supply abnormality is detected, the relay is shut off and the operation is performed when the electric load is abnormal And a welding determination device that determines whether or not the relay is welded during an abnormal operation of the electric load. The control device includes voltage conversion control means for converting the generated power at the electric load into voltage between the first and second power lines after converting the voltage according to the voltage command value. The welding determination device has in advance a fluctuation range of an output voltage output between the first and second power supply lines when voltage conversion is performed in a state where the power supply and the first and second power supply lines are connected. First setting means for setting the voltage command value to a first voltage that is less than or equal to the lower limit value of the fluctuation range, and second to set the voltage command value to a second voltage that is greater than or equal to the upper limit value of the fluctuation range Output between the first and second power supply lines during the execution of the voltage conversion control means and the switching means for executing switching between the first setting means and the second setting means at least once. Acquisition means for acquiring the output voltage, and welding determination means for determining welding of the connecting portion based on the relationship between the acquired output voltage and the voltage command value.

  Preferably, the welding determination means includes a first determination means for determining welding of the relay when the voltage command value is the first voltage, and a welding of the relay when the voltage command value is the second voltage. And determining that the connecting portion is normal when it is determined that the relay is not welded and is normal in each of the first and second determination means. To do.

  Preferably, the first setting means sets the first voltage to a voltage lower than the lower limit value of the fluctuation range, and the second setting means sets the second voltage to be higher than the upper limit value of the fluctuation range. Set to voltage. The first determination means determines that the relay is normal when the voltage command value is the first voltage and the output voltage is lower than the lower limit value of the fluctuation range for a predetermined period or longer. When the voltage command value is the second voltage, the second determination means determines that the relay is normal when the output voltage exceeds the upper limit value of the fluctuation range for a predetermined period or longer.

  Preferably, the welding determination means determines welding of the relay based on a deviation between the output voltage and the voltage command value.

  Preferably, the first setting means sets the first voltage to the lower limit value of the fluctuation range, and the second setting means sets the second voltage to the upper limit value of the fluctuation range. The switching means changes the voltage command value from the first voltage to the second voltage at a predetermined rate of change. When the voltage command value is the first voltage, the first determination means determines that the relay is welded when a period in which the deviation between the output voltage and the voltage command value exceeds a predetermined threshold continues for a predetermined period or longer. It is determined that When the voltage command value is changing at a predetermined rate of change, the second determination means determines that the relay is activated when a period in which the deviation between the output voltage and the voltage command value exceeds a predetermined threshold continues for a predetermined period or longer. Determined to be welded.

Preferably, the predetermined change rate is set based on the control responsiveness of the voltage conversion control means.
Preferably, the first setting means sets the first voltage to a voltage lower than the lower limit value of the fluctuation range, and the second setting means sets the second voltage to be higher than the upper limit value of the fluctuation range. Set to voltage. The welding determination means is acquired when the voltage command value is the first voltage and the first calculation means for calculating the average value of the output voltages acquired when the voltage command value is the first voltage, and when the voltage command value is the second voltage When the deviation of the average value calculated by the second calculation means for calculating the average value of the output voltage and the first and second calculation means exceeds the fluctuation range, the relay is not welded, Determining means for determining normality.

  According to another aspect of the present invention, there is provided a relay welding determination method in a power supply device, the power supply device including a power supply provided to be able to supply a DC voltage to the first and second power supply lines, a power supply, and a first power supply. And a relay that performs connection and disconnection with the second power supply line, and a voltage converter that performs voltage conversion between the first and second power supply lines and the electric load in accordance with a voltage command value. The relay welding determination method includes a step of controlling the operation when the electric load is abnormal by shutting off the relay when a power supply abnormality is detected, and a step of determining the welding of the relay in the operation when the electric load is abnormal Is provided. The step of controlling the operation when the electric load is abnormal includes the step of converting the generated power at the electric load according to the voltage command value and outputting the voltage between the first and second power lines. The step of determining the welding of the relay includes a fluctuation range of an output voltage output between the first and second power supply lines when voltage conversion is performed in a state where the power supply and the first and second power supply lines are connected. And setting the voltage command value to a first voltage that is less than or equal to the lower limit value of the fluctuation range; and setting the voltage command value to a second voltage that is greater than or equal to the upper limit value of the fluctuation range; Switching between the step of setting to the first voltage and the step of setting to the second voltage at least once, and an output output between the first and second power lines during the voltage conversion The method includes a step of acquiring a voltage and a step of determining welding of the relay based on a relationship between the acquired output voltage and a voltage command value.

  Preferably, the step of determining the welding of the relay includes the step of determining the welding of the relay when the voltage command value is the first voltage, and the welding of the relay when the voltage command value is the second voltage. And when the voltage command value is the first voltage and when the voltage command value is the second voltage, the relay is not welded and is determined to be normal. And determining that it is normal.

  Preferably, the step of setting the voltage command value to the first voltage sets the first voltage to a voltage lower than the lower limit value of the fluctuation range. The step of setting the voltage command value to the second voltage sets the second voltage to a voltage higher than the upper limit value of the fluctuation range. When the voltage command value is the first voltage, the step of determining the welding of the relay determines that the relay is normal when the output voltage continues below a lower limit value of the fluctuation range for a predetermined period or longer. . When the voltage command value is the second voltage, the step of determining the welding of the relay determines that the relay is normal when the output voltage exceeds the upper limit value of the fluctuation range for a predetermined period or longer. .

  Preferably, the step of determining the welding of the relay determines the welding of the relay based on a deviation between the output voltage and the voltage command value.

  Preferably, the step of setting the voltage command value to the first voltage sets the first voltage to the lower limit value of the fluctuation range. In the step of setting the voltage command value to the second voltage, the second voltage is set to the upper limit value of the fluctuation range. The switching means changes the voltage command value from the first voltage to the second voltage at a predetermined rate of change. When the voltage command value is the first voltage, the step of determining whether the relay is welded is performed when the connection unit has a period when the deviation between the output voltage and the voltage command value exceeds a predetermined threshold for a predetermined period or longer. Determined to be welded. When the voltage command value is the second voltage, the step of determining the welding of the relay is performed when the deviation between the output voltage and the voltage command value is a predetermined value when the voltage command value is changing at a predetermined rate of change. When the period exceeding the threshold continues for a predetermined period or longer, it is determined that the relay is welded.

Preferably, the predetermined change rate is set based on the control responsiveness of the voltage conversion control means.
Preferably, the step of setting the voltage command value to the first voltage sets the first voltage to a voltage lower than the lower limit value of the fluctuation range. The step of setting the voltage command value to the second voltage sets the second voltage to a voltage higher than the upper limit value of the fluctuation range. The step of determining the welding of the relay is acquired when the average value of the output voltage acquired when the voltage command value is the first voltage and when the voltage command value is the second voltage. Deviation between the step of calculating the average value of the output voltage, the average value calculated when the voltage command value is the first voltage, and the average value calculated when the voltage command value is the second voltage However, if the variation range is exceeded, the relay is not welded and is determined to be normal.

  According to the present invention, it is possible to perform battery-less traveling in a state where the power source is reliably shut off.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

[Embodiment 1]
FIG. 1 is a block diagram illustrating a configuration of a vehicle on which a power supply device according to Embodiment 1 of the present invention is mounted.

  Referring to FIG. 1, a hybrid vehicle 100 according to the present invention includes a battery 10, a hybrid ECU (Electronic Control Unit) 15, a PCU (Power Control Unit) 20, a power output device 30, and a differential gear (Differential Gear). 40, front wheels 50L and 50R, rear wheels 60L and 60R, front seats 70L and 70R, and a rear seat 80.

  The battery 10 is formed of a secondary battery such as nickel metal hydride or lithium ion, for example, and supplies a DC voltage to the PCU 20 and is charged by the DC voltage from the PCU 20. The battery 10 is disposed, for example, at the rear portion of the rear seat 80 and is electrically connected to the PCU 20. The PCU 20 collectively indicates power converters required in the hybrid vehicle 100.

  Various sensor outputs 17 from various sensors indicating driving conditions and vehicle conditions are input to the hybrid ECU 15. The various sensor outputs 17 include an accelerator opening, a wheel speed sensor output, and the like corresponding to an accelerator depression amount detected by a position sensor disposed on the accelerator pedal 35. The hybrid ECU 15 comprehensively performs various controls relating to the hybrid vehicle 100 based on these input sensor outputs.

  Power output device 30 is provided as a wheel driving force source, and includes an engine and / or motor generators MG1 and MG2. These are mechanically coupled via a power split mechanism PSD (FIG. 2). Then, according to the traveling state of the hybrid vehicle 100, the driving force is distributed and combined among the three parties via the power split mechanism PSD, and as a result, the front wheels 50L and 50R are driven. The DG 40 transmits the power from the power output device 30 to the front wheels 50L and 50R, and transmits the rotational force of the front wheels 50L and 50R to the power output device 30.

  Thereby, motive power output device 30 transmits the power from engine and / or motor generators MG1, MG2 to front wheels 50L, 50R via DG 40 to drive front wheels 50L, 50R. In addition, power output device 30 generates power by the rotational force of motor generators MG1 and MG2 by front wheels 50L and 50R, and supplies the generated power to PCU 20.

  Motor generators MG1 and MG2 can function as both a generator and an electric motor, but motor generator MG1 mainly operates as a generator, and motor generator MG2 mainly operates as an electric motor.

  Specifically, motor generator MG1 is used as a starter that starts the engine during acceleration. At this time, motor generator MG1 is supplied with electric power from battery 10 and is driven as an electric motor, and cranks and starts the engine.

  Further, after the engine is started, motor generator MG1 is rotated by the driving force of the engine transmitted through the power split mechanism to generate electric power.

  Motor generator MG2 is driven by at least one of the electric power stored in battery 10 and the electric power generated by motor generator MG1. The driving force of motor generator MG2 is transmitted to the driving shafts of front wheels 50L and 50R via DG40. Thereby, motor generator MG2 assists the engine to travel the vehicle, or travels the vehicle only by its own driving force.

  At the time of regenerative braking of the vehicle, motor generator MG2 is driven by front wheels 50L and 50R to operate as a generator. At this time, the regenerative power generated by motor generator MG2 is charged to battery 10 via PCU 20.

  PCU 20 boosts the DC voltage from battery 10 and converts the boosted DC voltage into an AC voltage in accordance with a control instruction from hybrid ECU 15 during powering operation of motor generators MG 1, MG 2. Drive control of included motor generators MG1, MG2 is performed.

  In addition, during regenerative braking of motor generators MG1 and MG2, PCU 20 charges battery 10 by converting the AC voltage generated by motor generators MG1 and MG2 into a DC voltage in accordance with a control instruction from hybrid ECU 15.

  Thus, in hybrid vehicle 100, “power supply device” that drives and controls motor generators MG <b> 1 and MG <b> 2 is configured by battery 10, PCU 20, and part of hybrid ECU 15 that controls PCU 20.

  However, in this power supply device, if an abnormality that makes battery 10 unusable occurs due to a failure of battery 10 or a sensor that detects the charge / discharge state of battery 10, drive control of motor generators MG1 and MG2 is performed. Since the vehicle becomes unstable, it may be difficult to travel the vehicle.

  Therefore, when an abnormality occurs in the battery 10 in this way, the hybrid ECU 15 disconnects (turns off) the system main relay for connecting the battery 10 and the power supply line, thereby removing the battery 10 from the power supply device. Cut off. Then, a part of the motive power output from the engine is output to the drive shaft with a required torque accompanied by power-power and power-power conversion by the motor generator MG1 and the motor generator MG2. Let it run. Hereinafter, such traveling without using the battery 10 is also referred to as “battery-less traveling”.

Next, the configuration of the power supply device according to the present invention will be described.
FIG. 2 is a block diagram showing the configuration of the power supply device according to the present invention.

  Referring to FIG. 2, a power supply device according to the present invention includes a battery 10 corresponding to a “power source” and a portion related to drive control of motor generators MG1 and MG2 in PCU 20 (hereinafter, this portion is also simply referred to as “PCU 20”. And a portion for controlling the PCU 20 in the hybrid ECU 15.

  PCU 20 includes system main relays SMR1, SMR2, converter 110, capacitors C1, C2, inverters 131, 132 corresponding to motor generators MG1, MG2, and MGECU 140, respectively.

  System main relays SMR1 and SMR2 conduct / cut off the power supply path from battery 10 to inverters 131 and 132. Specifically, system main relay SMR 1 is connected between the positive electrode of battery 10 and power supply line 101. System main relay SMR <b> 2 is connected between the negative electrode of battery 10 and ground line 102. Although illustration is omitted, the system main relay SMR3 may be further connected between the negative electrode of the battery 10 and the earth line 102 via a resistor. System main relays SMR1 and SMR2 are turned on / off (on / off) by signal SE from MGECU 140, respectively.

  Capacitor C1 is connected between power supply line 101 and ground line 102, and smoothes voltage fluctuations between power supply line 101 and ground line 102. Voltage sensor 120 detects voltage VL across capacitor C1 and outputs the detected voltage VL to MGECU 140.

  For example, converter 110 includes a step-up / step-down chopper circuit, and includes a reactor L1, power semiconductor switching elements (hereinafter also simply referred to as switching elements) Q1 and Q2, and diodes D1 and D2. As the switching element in this embodiment, for example, an IGBT (Insulated Gate Bipolar Transistor) is applied. Converter 110 boosts the DC voltage supplied from capacitor C1 and supplies it to capacitor C2. More specifically, when converter 110 receives switching control signal PWMC from MGECU 140, converter boosts the DC voltage according to the period during which switching element Q2 is turned on by switching control signal PWMC, and supplies it to capacitor C2.

  In addition, when converter 110 receives switching control signal PWMC from MGECU 140, converter 110 steps down the DC voltage supplied from capacitor C <b> 2 and charges battery 10.

  A capacitor C <b> 2 is connected between the power supply line 103 and the earth line 102. Capacitor C2 smoothes the DC voltage from converter 110 and supplies the smoothed DC voltage to inverters 131 and 132. Voltage sensor 122 detects voltage VH across capacitor C2, and outputs the detected voltage VH to MGECU 140.

  Inverter 131 returns electric power generated by motor generator MG1 to converter 110 by the rotational torque transmitted from the crankshaft of engine ENG.

  Inverter 131 includes switching elements Q3 and Q4 constituting a U-phase arm, switching elements Q5 and Q6 constituting a V-phase arm, and switching elements Q7 and Q8 constituting a W-phase arm. Further, anti-parallel diodes D3 to D8 that flow current from the emitter side to the collector side are connected between the collectors and emitters of the switching elements Q3 to Q8, respectively. Switching elements Q3 to Q8 are subjected to on / off control, that is, switching control, based on switching control signal PWMI1 from MGECU 140.

  Motor generator MG1 is a three-phase permanent magnet motor configured by commonly connecting a U-phase coil, a V-phase coil, and a W-phase coil to a neutral point. An intermediate point of switching elements Q3 and Q4 where a U-phase voltage is generated by switching control is electrically connected to a U-phase coil. Similarly, the intermediate point of switching elements Q5 and Q6 where the V-phase voltage is generated is electrically connected to the V-phase coil. Furthermore, the intermediate point of switching elements Q7 and Q8 where the W-phase voltage is generated is electrically connected to the W-phase coil.

  Inverter 132 is connected to converter 110 in parallel with inverter 131. Inverter 132 converts the DC voltage output from converter 110 into a three-phase AC voltage and outputs it to motor generator MG2 that drives front wheels 50L and 50R (FIG. 1). Inverter 132 returns the electric power generated in motor generator MG2 to converter 110 as a result of regenerative braking.

  Although the internal configuration of inverter 132 is not shown, it is similar to inverter 131, and detailed description will not be repeated. Switching elements constituting each phase arm of inverter 132 are subjected to switching control based on switching control signal PWMI2 from MGECU 140.

  Similar to motor generator MG1, motor generator MG2 is a three-phase permanent magnet motor configured by commonly connecting a U-phase coil, a V-phase coil, and a W-phase coil to a neutral point. An intermediate point of each phase arm of inverter 132 is electrically connected to a U-phase coil, a V-phase coil, and a W-phase coil of motor generator MG2.

  Based on the various sensor outputs 17, hybrid ECU 15 generates operation commands for motor generators MG1 and MG2 and outputs them to MGECU 140 so that desired driving force generation and power generation are performed. This operation command includes an operation permission / prohibition instruction, a torque command value, a rotation speed command, and the like of each motor generator MG1, MG2.

  MGECU 140 receives an operation command from hybrid ECU 15 by feedback control based on a motor drive current of each phase from a current sensor and a position sensor (both not shown) arranged in motor generator MG1 and a detected value of the rotation angle of the rotor. The switching control signal PWMI1 for controlling the switching operation of the switching elements Q3 to Q8 is generated so that the motor generator MG1 operates according to the above.

  Further, MGECU 140 receives feedback from hybrid ECU 15 by feedback control based on the detected values of the motor drive current of each phase and the rotation angle of the rotor from a current sensor and a position sensor (both not shown) arranged in motor generator MG2. A switching control signal PWMI2 for controlling the switching operation of switching elements Q3 to Q8 is generated so that motor generator MG2 operates in accordance with the operation command.

  Further, based on the operation command from hybrid ECU 15, MGECU 140 is a motor operating voltage for increasing the efficiency of motor generators MG1 and MG2 (the voltage at both ends of converter C2, which corresponds to the input voltage of inverters 131 and 132). The same applies hereinafter.) The voltage command value of VH is calculated. Then, MGECU 140 determines the boost ratio (VH / VL) in converter 110 based on the calculated voltage command value, and generates switching control signal PWMC so that this boost ratio is realized.

  Further, MGECU 140 generates switching control signal PWMC so as to step down DC voltage (motor operating voltage VH) supplied from inverters 131 and 132 during regenerative braking of hybrid vehicle 100. That is, during regenerative braking, converter 110 turns on and off switching elements Q1 and Q2 in response to switching control signal PWMC, thereby stepping down motor operating voltage VH and reducing DC voltage VL to power supply line 101 and ground line 102. Output in between. Battery 10 is charged by DC voltage VL from converter 110. Thus, converter 110 can also step down motor operating voltage VH to DC voltage VL, and thus has a bidirectional converter function.

PCU 20 further includes a DC / DC converter 130 and an auxiliary battery SB.
DC / DC converter 130 is connected between power supply line 101 and earth line 102, and steps down DC power from converter 110 to a predetermined DC voltage and supplies it to auxiliary battery SB and low-voltage auxiliary machines (not shown). To do. The low-voltage auxiliary machines are a general term for auxiliary machines that operate at a low voltage compared to the output voltage of the battery 10, and as an example, ECU related to controlling the traveling of the vehicle such as the hybrid ECU 15, a lighting device, and an ignition device. Including electric pumps.

  Auxiliary battery SB is composed of, for example, a lead storage battery, and is connected to the output side of DC / DC converter 130 and charged with DC power from DC / DC converter 130, while the electric power stored in low-voltage auxiliary machines is stored. Supply. That is, the auxiliary battery SB also functions as a power buffer for compensating for an imbalance between the output power of the DC / DC converter 130 and the demand power of the low-voltage auxiliary machines.

  Here, in the power supply device having the configuration of FIG. 2, as described above, when an abnormality occurs in the battery 10, the hybrid ECU 15 prohibits charging / discharging of the battery 10 and causes the hybrid vehicle 100 to run in a batteryless manner.

  Specifically, when hybrid ECU 15 receives information on abnormality of battery 10, MGECU 140 generates a cut-off command (hereinafter referred to as an SMR cut-off command) for non-conducting (turning off) system main relays SMR1, SMR2. To send. The system main relays SMR1 and SMR2 are turned off because the voltage generated between the power supply line 101 and the earth line 102 is lower (or higher) than the voltage between the terminals of the battery 10 due to power generation by the back electromotive force of the motor generator MG1. Because there is a case.

  When MGECU 140 receives the SMR cutoff command from hybrid ECU 15, MGECU 140 generates signal SE to turn off system main relays SMR1 and SMR2. As a result, the battery 10 is disconnected from the power supply device.

  Then, MGECU 140 drives and controls engine ENG and motor generators MG1 and MG2 so as to supply back electromotive force generated by rotation of motor generator MG1 accompanying rotation of engine ENG to motor generator MG2. The torque based on this is output to the drive shaft. As a result, the hybrid vehicle 100 can run without a battery. At this time, power obtained by subtracting the power consumption of motor generator MG2 from the back electromotive force generated in motor generator MG1 is stored in capacitor C2.

  Further, the MGECU 140 steps down the power stored in the capacitor C2 by the converter 110 and supplies it to the DC / DC converter 130. This is to prevent the low-voltage auxiliary machinery (particularly related to the ECU) from becoming normally inoperable by supplying power to the auxiliary battery SB and the low-voltage auxiliary machinery.

  That is, during execution of battery-less running, converter 110 is controlled to step down motor operating voltage VH to DC voltage VL. In this step-down control, the MGECU 140 sets a voltage command value VL * that is a target voltage when the motor operating voltage VH is stepped down. Then, MGECU 140 generates a switching control signal PWMC for stepping down motor operating voltage VH to DC voltage VL so that DC voltage VL becomes set voltage command value VL *, and outputs it to converter 110.

  Voltage command value VL * is set to a predetermined voltage substantially equal to inter-terminal voltage Vb of battery 10. This is because the power supply to the auxiliary battery SB and the low-voltage auxiliary machines is continued even after the battery 10 is shut off. Hereinafter, the step-down control of converter 110 for keeping DC voltage VL at a constant voltage in this way is also referred to as “VL constant control”.

  By performing such a series of controls, it is possible to output power without charging / discharging the battery 10 during control during battery-less travel. However, when system main relays SMR1 and SMR2 are welded, the energized state continues even when system main relays SMR1 and SMR2 are turned off. Problem arises.

  Therefore, the power supply device according to the present embodiment is configured to determine the welding of system main relays SMR1 and SMR2 at the initial stage when the above-described VL constant control is performed.

  Specifically, the welding determination of system main relays SMR1 and SMR2 is performed by intentionally changing voltage command value VL * in VL constant control from the above-described predetermined voltage (substantially terminal voltage Vb of battery 10). It is. If it is determined that the system main relays SMR1 and SMR2 are not welded based on the relationship between the DC voltage VL and the voltage command value VL *, the hybrid ECU 15 determines that the hybrid ECU 15 is a hybrid vehicle. 100 battery-less running is permitted.

  By adopting such a configuration, it becomes possible to perform the battery-less traveling of the hybrid vehicle 100 under a situation in which it is guaranteed that the battery 10 is reliably disconnected from the power supply device. Since the welding determination is performed using VL constant control as described below, it can be performed with an existing apparatus configuration without adding new parts such as a welding detection circuit.

(System main relay welding judgment)
Hereinafter, a control structure of hybrid ECU 15 for determining welding of system main relays SMR1, SMR2 will be described with reference to FIG.

  FIG. 3 is a block diagram showing a control structure in hybrid ECU 15 according to the embodiment of the present invention. The control block shown in FIG. 3 is typically realized by the hybrid ECU 15 executing a program stored in advance, but a part or all of the configuration may be realized as dedicated hardware.

  Referring to FIG. 3, hybrid ECU 15 includes an HV control unit 160, an SMR welding determination unit 162, and a timer 164.

  Hybrid ECU 15 receives information regarding abnormality of battery 10 detected by battery ECU 200 that controls charging and discharging of battery 10.

  When the HV control unit 160 receives the abnormality information of the battery 10, it issues an SMR cutoff command to the MGECU 140. Furthermore, the HV control unit 160 generates a VL constant request for performing the above-described VL constant control, and sends it to the MGECU 140.

  The timer 164 measures an elapsed time (hereinafter also referred to as an elapsed time after the request) t after the VL constant request is issued.

  The MGECU 140 includes an inverter control unit 142 and a converter control unit 144. Converter control unit 144 generates signal SE for turning off system main relays SMR1 and SMR2 in accordance with the SMR cutoff command from HV control unit 160. The converter control unit 144 further sets a target voltage (voltage command value) VL * for stepping down the motor operating voltage VH in response to a constant VL request, and sets the set voltage command value VL * and the motor operating voltage VH. And a switching control signal PWMC for stepping down the motor operating voltage VH to the voltage command value VL * so that the DC voltage VL becomes the voltage command value VL * on the basis of the DC voltage VL and outputting it to the converter 110 To do.

  When SMR welding determination unit 162 receives abnormality information of battery 10 from battery ECU 200, SMR welding determination unit 162 determines welding of system main relays SMR1 and SMR2 at the initial stage when VL constant control is performed.

  Specifically, the SMR welding determination unit 162 changes the voltage command value VL * in the VL constant control to a predetermined voltage (substantially charge / discharge of the battery 10) in response to the VL constant request being issued. It corresponds to the voltage Vb.) Note that the fluctuation range of the voltage command value VL * at this time is set to be equal to or greater than the fluctuation range of the DC voltage VL acquired in advance with the battery 10 connected, as will be described later.

  When converter control unit 144 receives voltage command value VL * from SMR welding determination unit 162, DC voltage VL is converted to voltage command value VL based on voltage command value VL *, motor operating voltage VH, and DC voltage VL. A switching control signal PWMC for stepping down the motor operating voltage VH to the voltage command value VL * so as to become * is generated and output to the converter 110. Thereby, converter 110 steps down motor operating voltage VH to DC voltage VL so that DC voltage VL becomes voltage command value VL *. Voltage sensor 120 detects DC voltage VL after step-down and outputs it to SMR welding determination unit 162.

  When SMR welding determination unit 162 receives DC voltage VL from voltage sensor 120, SMR welding determination unit 162 determines welding of system main relays SMR1 and SMR2 based on the relationship between DC voltage VL and voltage command value VL *. When it is determined that system main relay SMR1 is not welded (normal), SMR welding determination unit 162 displays SMR determination flag FSMR indicating whether system main relays SMR1 and SMR2 are welded. Is set to “1” indicating normal. On the other hand, when it is determined that the system main relays SMR1 and SMR2 are welded, the SMR welding determination unit 162 displays an SMR determination flag FSMR indicating that the system main relay SMR1 is welded “0”. To "".

  Finally, when the SMR determination flag FSMR is “1”, the HV control unit 160 generates an operation command for the motor generators MG1 and MG2 for causing the hybrid vehicle 100 to run in a batteryless manner, and sends the operation command to the MGECU 140. . When the MGECU 140 performs the drive control of the motor generators MG1 and MG2 described above, the hybrid vehicle 100 can run without a battery.

  On the other hand, when the SMR determination flag FSMR is “0”, the HV control unit 160 causes the hybrid vehicle 100 to transition from the Ready state in which the vehicle is permitted to travel to the off state. Thereby, the hybrid vehicle 100 stops traveling.

  FIG. 4 is a timing chart for explaining the welding determination operation of system main relays SMR1, SMR2 according to the first embodiment of the present invention.

  Referring to FIG. 4, HV control unit 160 (FIG. 3) of hybrid ECU 15 receives an abnormality information of battery 10 detected by battery ECU 200, and issues an SMR cutoff command at time t1. Converter control unit 144 (FIG. 3) of MGECU 140 generates signal SE for shutting off system main relays SMR1 and SMR2 in accordance with the SMR cutoff command and outputs the signal SE to system main relays SMR1 and SMR2.

  Further, HV control unit 160 generates a VL constant request at time t 2 and sends it to converter control unit 144. Upon receiving the VL constant request, converter control unit 144 starts VL constant control for setting DC voltage VL to voltage command value VL *.

  At this time, the SMR welding determination unit 162 of the hybrid ECU 15 intentionally changes the voltage command value VL * in the constant VL control from a preset voltage (substantially equivalent to the charge / discharge voltage Vb of the battery 10). Let

  Specifically, SMR welding determination unit 162 acquires in advance the fluctuation range of DC voltage VL when VL constant control is performed with battery 10 connected to the power supply device. In FIG. 4, the DC voltage VL has a fluctuation range of ± ΔV with the terminal voltage Vb of the battery 10 as the center. The voltage V1 in the figure indicates the lower limit value (Vb−ΔV) of the fluctuation range, and the voltage V2 indicates the upper limit value (Vb + ΔV) of the fluctuation range.

  SMR welding determination unit 162 sets two voltage command values VL * based on the fluctuation range of DC voltage VL. One voltage command value VL * is set to a voltage lower than the voltage V1 that is the lower limit value, and the other voltage command value VL * is set to a voltage that is higher than the voltage V2 that is the upper limit value. The SMR welding determination unit 162 switches these two voltage command values VL * at least once. SMR welding determination unit 162 then includes system main relays SMR1, SMR2 based on DC voltage VL detected by voltage sensor 120 when converter 110 performs a step-down operation according to each of two voltage command values VL *. Determine welding. That is, according to the power supply device according to the present embodiment, determination of welding of system main relays SMR1, SMR2 is performed at least twice.

  For example, in the case of FIG. 4, since voltage command value VL * is switched once, determination of welding of system main relays SMR1, SMR2 is performed twice.

  Specifically, when a VL constant request is issued at time t2, SMR welding determination unit 162 first sets voltage command value VL * to a voltage lower than voltage V1. Thereby, converter 110 performs a step-down operation of motor operating voltage VH so that DC voltage VL becomes voltage command value VL * (<V1). And in the period T1 from the time t2 to the time t4, the SMR welding determination part 162 performs the 1st welding determination.

  At this time, when system main relays SMR1 and SMR2 are not welded, DC voltage VL changes to a voltage lower than voltage V1 following voltage command value VL * as shown by line LN1. On the other hand, when system main relays SMR1 and SMR2 are welded, DC voltage VL is substantially equal to terminal voltage Vb of battery 10 without following voltage command value VL * as shown by line LN2. Maintain voltage level.

  Therefore, the SMR welding determination unit 162 determines that the system main relays SMR1 and SMR2 are not welded when the period during which the DC voltage VL from the voltage sensor 120 is lower than the voltage V1 continues for a predetermined reference time Ta or more. judge. At this time, the SMR welding determination unit 162 sets the determination flag F1 indicating the first welding determination result to “1” as indicated by the line LN3.

  On the other hand, when the period during which DC voltage VL is lower than voltage V1 is shorter than predetermined reference time Ta, SMR welding determination unit 162 determines that system main relays SMR1, SMR2 are welded. In this case, the SMR welding determination unit 162 resets the determination flag F1 to “0” as indicated by a line LN4.

  Note that the predetermined reference time Ta is set in advance to a time sufficient to avoid erroneous determination caused by noise superimposed on the DC voltage VL or undershoot of the DC voltage VL during the step-down operation of the converter 110.

  Next, SMR welding determination unit 162 sets voltage command value VL * to a voltage higher than voltage V2. Thereby, converter 110 performs a step-down operation of motor operating voltage VH so that DC voltage VL becomes voltage command value VL * (> V2). In the period from time t4 to time t6, the SMR welding determination unit 162 performs the second welding determination.

  At this time, when system main relays SMR1 and SMR2 are not welded, DC voltage VL changes to a voltage higher than voltage V2 following voltage command value VL * as indicated by line LN1. On the other hand, when system main relays SMR1 and SMR2 are welded, DC voltage VL is substantially equal to terminal voltage Vb of battery 10 without following voltage command value VL * as shown by line LN2. Maintain voltage level.

  Therefore, SMR welding determination unit 162 determines that system main relays SMR1, SMR2 are not welded when the period in which DC voltage VL from voltage sensor 120 exceeds voltage V2 continues for a predetermined reference time Tb or longer. . In this case, the SMR welding determination unit 162 sets the determination flag F2 indicating the second welding determination result to “1” as indicated by the line LN5.

  On the other hand, when the period during which DC voltage VL exceeds voltage V2 is shorter than predetermined reference time Tb, it is determined that system main relays SMR1, SMR2 are welded. In this case, the SMR welding determination unit 162 resets the determination flag F2 to “0” as indicated by a line LN6.

  Note that the predetermined reference time Tb is sufficient to avoid erroneous determination due to noise superimposed on the DC voltage VL or overshoot of the DC voltage VL during the step-down operation of the converter 110, as with the reference time Ta described above. It is preset in time.

  Finally, the SMR welding determination unit 162 refers to the determination flags F1 and F2, and when the determination flag F1 is “1” and the determination flag F2 is “1”, the system main relays SMR1 and SMR2 are welded. Judged not (normal). Then, the SMR determination flag FSMR is set to “1”.

  On the other hand, when at least one of determination flags F1 and F2 is “0”, it is determined that system main relays SMR1 and SMR2 are welded. The SMR determination flag FSMR is reset to “0”.

  Thus, according to the present embodiment, voltage command value VL * is set on the low voltage side and high voltage side of the fluctuation range of DC voltage VL with battery 10 connected, and each voltage command value VL * is set. The welding determination of system main relays SMR1, SMR2 is performed based on the followability of DC voltage VL with respect to. Therefore, welding of system main relays SMR1 and SMR2 can be reliably detected. As a result, it is possible to perform the battery-less traveling of the hybrid vehicle 100 in a state in which it is guaranteed that the battery 10 is reliably shut off.

  Furthermore, since the VL constant control is used, it is possible to perform welding determination with an existing apparatus configuration without adding new parts such as a welding detection circuit.

The above processing can be summarized in a processing flow as shown in FIGS.
(flowchart)
FIGS. 5 and 6 are flowcharts illustrating a processing procedure of the welding determination operation for system main relays SMR1, SMR2 by hybrid ECU 15 according to the first embodiment of the present invention. 5 and 6 is realized by the hybrid ECU 15 (FIG. 2) functioning as the control blocks shown in FIG.

  Referring to FIG. 5, when hybrid ECU 15 that functions as HV control unit 160 detects an abnormality of battery 10 based on the abnormality information from battery ECU (step S01), it issues an SMR cutoff command (step S02). The HV control unit 160 further issues a VL constant request (step S03). Thereby, in converter 110, VL constant control is started.

  Next, the hybrid ECU 15 functioning as the SMR welding determination unit 162 sets the voltage command value VL * in the VL constant control to a voltage lower than the voltage V1 (step S04). The timer 164 measures an elapsed time (elapsed time after request) t after the VL constant request is issued (step S05). The SMR welding determination unit 162 acquires the elapsed time t after the request timed by the timer 164.

  SMR welding determination unit 162 further acquires DC voltage VL from voltage sensor 120 (step S06). Then, the SMR welding determination unit 162 determines whether the post-request elapsed time t has exceeded a predetermined determination period T1 (step S07). The predetermined determination period T1 is set in advance as a period for performing the first welding determination as shown in FIG.

  When elapsed time t after request is equal to or shorter than predetermined determination period T1 (NO in step S07), the process returns to step S06.

  On the other hand, when the post-request elapsed period t exceeds the predetermined determination period T1 (YES in step S07), the SMR welding determination unit 162 obtains the acquired DC voltage VL and voltage V1. By comparing, it is determined whether or not the period during which the DC voltage V1 is lower than the voltage V1 continues for a predetermined reference period Ta or more (step S08).

  When DC voltage VL is lower than voltage V1 for a predetermined reference time Ta or longer (YES in step S08), SMR welding determination unit 162 determines that system main relays SMR1 and SMR2 are normal. The determination flag F1 is set to “1” (step S09).

  On the other hand, when the period during which DC voltage VL is lower than voltage V1 is shorter than predetermined period Ta (NO in step S08), SMR welding determination unit 162 causes system main relays SMR1 and SMR2 to weld. The determination flag F1 is reset to “0” (step S10).

  Next, the SMR welding determination unit 162 determines whether or not the determination flag F1 is “1” (step S11). If determination flag F1 is not “1” (NO in step S11), SMR welding determination unit 162 determines that system main relays SMR1, SMR2 are welded, and sets SMR determination flag FSMR to “0”. (Step S22).

  When receiving the SMR determination flag FSMR, the HV control unit 160 causes the hybrid vehicle 100 to transition from the Ready state in which the vehicle is permitted to travel to the off state. As a result, the hybrid vehicle 100 stops traveling (step S23).

  On the other hand, when determination flag F1 is “1” (YES in step S11), SMR welding determination unit 162 sets voltage command value VL * to a voltage higher than voltage V2 (step S11). S12). The timer 164 measures the elapsed time t after the request (step S13). The SMR welding determination unit 162 acquires the elapsed time t after the request timed by the timer 164.

  SMR welding determination unit 162 further acquires DC voltage VL from voltage sensor 120 (step S14). Then, the SMR welding determination unit 162 determines whether or not the post-request elapsed time t has exceeded a predetermined period T2 (step S15). The predetermined period T2 is obtained by adding a predetermined determination period set in advance as a period for performing the second welding determination to the predetermined determination period T1.

  If the elapsed time after request t is equal to or shorter than the predetermined period T2 (NO in step S15), the process returns to step S14.

  On the other hand, when the post-request elapsed period t exceeds the predetermined period T2 (YES in step S15), the SMR welding determination unit 162 compares the acquired DC voltage VL with the voltage V2. Thus, it is determined whether or not the period during which the DC voltage V1 exceeds the voltage V2 continues for a predetermined reference period Tb or more (step S16).

  When the period in which DC voltage VL exceeds voltage V2 continues for a predetermined reference time Tb or more (in the case of YES in step S16), SMR welding determination unit 162 determines that system main relays SMR1 and SMR2 are normal. The determination flag F2 is set to “1” (step S17).

  On the other hand, when the period in which DC voltage VL exceeds voltage V2 is shorter than predetermined period Tb (NO in step S16), SMR welding determination unit 162 causes system main relays SMR1 and SMR2 to weld. The determination flag F2 is reset to “0” (step S18).

  Finally, the SMR welding determination unit 162 determines whether or not the determination flag F2 is “1” (step S19). When determination flag F2 is “1” (YES in step S19), SMR welding determination unit 162 determines that system main relays SMR1, SMR2 are normal, and sets SMR determination flag FSMR to “1”. (Step S20). When HV control unit 160 receives SMR determination flag FSMR, HV control unit 160 generates an operation command for motor generators MG1 and MG2 for causing hybrid vehicle 100 to travel in a battery-less manner, and sends it to MGECU 140. Thereby, the hybrid vehicle 100 performs battery-less traveling (step S21).

  On the other hand, when determination flag F2 is not “1” (that is, “0”) (NO in step S19), SMR welding determination unit 162 causes system main relays SMR1 and SMR2 to weld. SMR determination flag FSMR is reset to “0” (step S22).

  When receiving the SMR determination flag FSMR, the HV control unit 160 causes the hybrid vehicle 100 to transition from the Ready state in which the vehicle is permitted to travel to the off state. As a result, the hybrid vehicle 100 stops traveling (step S23).

  In the description of FIGS. 4 to 6, the welding determination operation of the system main relays SMR1 and SMR2 is illustrated when the voltage command value VL * is switched once. However, the voltage command value VL * is switched 2 times. More accurate determinations can be made by performing more than once. In this case, SMR welding determination unit 162 determines welding of system main relays SMR1 and SMR2 for each of voltage command value VL * after switching, and sets / resets a determination flag. Then, it is determined that the system main relays SMR1, SMR2 are normal in response to all the determination flags being set to “1”.

[Embodiment 2]
In the first embodiment, the configuration in which the welding of the system main relays SMR1 and SMR2 is determined based on the followability of the DC voltage VL when the voltage command value VL * in the VL constant control is changed has been described. In the following second and third embodiments, one mode of welding determination of the system main relays SMR1 and SMR2 will be further illustrated and described. Since the power supply devices according to Embodiments 2 and 3 have the same basic configuration as the power supply device shown in FIGS. 1 to 3, detailed description of the device configuration is omitted.

  FIG. 7 is a timing chart for explaining the welding determination operation of system main relays SMR1, SMR2 according to the second embodiment of the present invention.

  Referring to FIG. 7, HV control unit 160 (FIG. 3) of hybrid ECU 15 receives an abnormality information of battery 10 detected by battery ECU 200, and issues an SMR cutoff command at time t1. Converter control unit 144 (FIG. 3) of MGECU 140 generates signal SE for turning off system main relays SMR1 and SMR2 in accordance with the SMR cutoff command, and outputs the signal SE to system main relays SMR1 and SMR2.

  Further, HV control unit 160 generates a VL constant request at time t 2 and sends it to converter control unit 144. Upon receiving the VL constant request, converter control unit 144 starts VL constant control for setting DC voltage VL to voltage command value VL *.

  At this time, the SMR welding determination unit 162 of the hybrid ECU 15 intentionally changes the voltage command value VL * in the constant VL control from a preset voltage (substantially equivalent to the charge / discharge voltage Vb of the battery 10). Let

  Specifically, SMR welding determination unit 162 acquires in advance the fluctuation range of DC voltage VL when VL constant control is performed with battery 10 connected to the power supply device. In FIG. 7, the DC voltage VL has a fluctuation range of ± ΔV with the terminal voltage Vb of the battery 10 as the center. The voltage V1 in the figure indicates the lower limit value (Vb−ΔV) of the fluctuation range, and the voltage V2 indicates the upper limit value (Vb + ΔV) of the fluctuation range.

  The SMR welding determination unit 162 sets two voltage command values VL * based on the fluctuation range of the DC voltage VL. One voltage command value VL * is set to a voltage V1 that is a lower limit value, and the other voltage command value VL * is set to a voltage V2 that is an upper limit value. The SMR welding determination unit 162 switches these two voltage command values VL * at least once.

  SMR welding determination unit 162 then performs system main relays SMR1, SMR2 based on DC voltage VL detected by voltage sensor 120 when converter 110 performs a step-down operation according to each of two voltage command values VL *. Determine welding. That is, according to the power supply device according to the present embodiment, determination of welding of system main relays SMR1, SMR2 is performed at least twice.

  For example, in the case of FIG. 7, voltage command value VL * is switched once, and welding determination of system main relays SMR1, SMR2 is performed twice.

  Specifically, when a VL constant request is issued at time t2, SMR welding determination unit 162 first sets voltage command value VL * to voltage V1. Thereby, converter 110 performs a step-down operation of motor operating voltage VH so that DC voltage VL becomes voltage command value VL * (= V1). And in the period T1 from the time t2 to the time t12, the SMR welding determination part 162 performs the 1st welding determination.

  At this time, when system main relays SMR1 and SMR2 are not welded, DC voltage VL changes to voltage V1 following voltage command value VL * as shown by line LN11. On the other hand, when system main relays SMR1 and SMR2 are welded, DC voltage VL is substantially equal to terminal voltage Vb of battery 10 without following voltage command value VL * as shown by line LN12. Maintain voltage level. Alternatively, as shown by line LN13, a substantially constant voltage level is maintained within the fluctuation range of DC voltage VL.

  Therefore, SMR welding determination unit 162 calculates a deviation ΔVL (= | VL * −VL |) between DC voltage VL from voltage sensor 120 and voltage command value VL *. When the calculated deviation ΔVL is longer than the predetermined threshold Va for a predetermined reference period Ta or longer, it is determined that the system main relays SMR1, SMR2 are welded. At this time, the SMR welding determination unit 162 resets the determination flag F1 indicating the first welding determination result to “0” as indicated by a line LN15.

  On the other hand, if the calculated deviation ΔVL is longer than the predetermined threshold value Va, it is determined that the system main relays SMR1, SMR2 are not welded. In this case, the SMR welding determination unit 162 sets the determination flag F1 to “1” as indicated by the line LN4.

  Predetermined threshold value Va is set in advance to a value sufficient to avoid erroneous determination due to noise superimposed on DC voltage VL during the step-down operation of converter 110. The predetermined reference time Ta is also set in advance to a time sufficient to avoid erroneous determination due to noise superimposed on the DC voltage VL during the step-down operation of the converter 110.

  Next, the SMR welding determination unit 162 sets the voltage command value VL * to the voltage V2. At this time, as shown in FIG. 7, the SMR welding determination unit 162 sets the voltage command value VL * so as to change at a predetermined change rate with the voltage V2 as the final value. The predetermined rate of change is set in advance to a value that ensures the control response of DC voltage VL with respect to voltage command value VL *.

  Thereby, converter 110 performs a step-down operation of motor operating voltage VH so that DC voltage VL becomes voltage command value VL *. SMR welding determination section 162 performs the second welding determination after time t12.

  At this time, when system main relays SMR1 and SMR2 are not welded, DC voltage VL changes following voltage command value VL * as shown by line LN11. On the other hand, when system main relays SMR1 and SMR2 are welded, DC voltage VL does not follow voltage command value VL * as shown by line LN12 or LN13, and is within the fluctuation range of DC voltage VL. Maintain a substantially constant voltage level.

  Therefore, the SMR welding determination unit 162 determines that the period during which the difference ΔVL between the DC voltage VL from the voltage sensor 120 and the voltage command value VL * is larger than the predetermined threshold Va continues for a predetermined reference period Tb or more. Determines that the system main relays SMR1, SMR2 are welded. At this time, the SMR welding determination unit 162 resets a determination flag F2 indicating the second welding determination result to “0” as indicated by a line LN17.

  On the other hand, if the calculated deviation ΔVL is longer than the predetermined threshold value Va, it is determined that the system main relays SMR1, SMR2 are not welded. In this case, the SMR welding determination unit 162 sets the determination flag F1 to “1” as indicated by the line LN16.

  The predetermined reference time Tb is set in advance to a time sufficient to avoid erroneous determination in consideration of the control response of the converter 110.

  Finally, the SMR welding determination unit 162 determines that the system main relays SMR1 and SMR2 are normal when the determination flag F1 is “1” and the determination flag F2 is “1”. Then, the SMR determination flag FSMR is set to “1”.

  On the other hand, when at least one of determination flags F1 and F2 is “0”, it is determined that system main relays SMR1 and SMR2 are welded. The SMR determination flag FSMR is reset to “0”.

The above processing can be summarized in a processing flow as shown in FIGS.
(flowchart)
FIGS. 8 and 9 are flowcharts illustrating a processing procedure of the welding determination operation for system main relays SMR1 and SMR2 by hybrid ECU 15 according to the second embodiment of the present invention. 8 and FIG. 9 is realized by the hybrid ECU 15 (FIG. 2) functioning as the control blocks shown in FIG.

  Referring to FIG. 8, when hybrid ECU 15 that functions as HV control unit 160 detects an abnormality of battery 10 based on the abnormality information from battery ECU 200 (step S01), it issues an SMR cutoff command (step S02). The HV control unit 160 further issues a VL constant request (step S03). Thereby, in converter 110, VL constant control is started.

  Next, the hybrid ECU 15 functioning as the SMR welding determination unit 162 sets the voltage command value VL * in the VL constant control to the voltage V1 (step S041). The timer 164 measures a post-request elapsed time t, which is an elapsed time after the VL constant request is issued (step S05). The SMR welding determination unit 162 acquires the elapsed time t after the request timed by the timer 164.

  SMR welding determination unit 162 further acquires DC voltage VL from voltage sensor 120 (step S06). Then, the SMR welding determination unit 162 calculates a deviation ΔVL between the acquired DC voltage VL and the voltage command value VL * (step S061).

  Then, the SMR welding determination unit 162 determines whether the post-request elapsed time t has exceeded a predetermined determination period T1 (step S07). The predetermined determination period T1 is set in advance as a period for performing the first welding determination as shown in FIG.

  When elapsed time t after request is equal to or shorter than predetermined determination period T1 (NO in step S07), the process returns to step S06.

  On the other hand, when the post-request elapsed period t exceeds the predetermined determination period T1 (YES in step S07), the SMR welding determination unit 162 determines that the calculated deviation ΔVL has a predetermined threshold value Va. It is determined whether or not the longer period continues for a predetermined reference period Ta or more (step S081).

  When the period in which deviation ΔVL exceeds predetermined threshold value Va is shorter than predetermined reference time Ta (NO in step S081), SMR welding determination unit 162 determines that system main relays SMR1 and SMR2 are normal. Then, the determination flag F1 is set to “1” (step S09).

  On the other hand, when the period in which deviation ΔVL exceeds predetermined threshold value Va continues for a predetermined reference period Ta or more (in the case of YES in step S081), SMR welding determination unit 162 causes system main relays SMR1 and SMR2 to It determines with welding and resets the determination flag F1 to "0" (step S10).

  Next, the SMR welding determination unit 162 determines whether or not the determination flag F1 is “1” (step S11). If determination flag F1 is not “1” (NO in step S11), SMR welding determination unit 162 determines that system main relays SMR1, SMR2 are welded, and sets SMR determination flag FSMR to “0”. (Step S22).

  When receiving the SMR determination flag FSMR, the HV control unit 160 causes the hybrid vehicle 100 to transition from the Ready state in which the vehicle is permitted to travel to the off state. As a result, the hybrid vehicle 100 stops traveling (step S23).

  On the other hand, when the determination flag F1 is “1” (YES in step S11), the SMR welding determination unit 162 causes the voltage command to change at a predetermined change rate toward the voltage V2. A value VL * is set (step S120).

  When the SMR welding determination unit 162 acquires the DC voltage VL from the voltage sensor 120 (step S14), it calculates a deviation ΔVL between the acquired DC voltage VL and the voltage command value VL * (step S141).

  Then, the SMR welding determination unit 162 determines whether or not the period during which the calculated deviation ΔVL exceeds the predetermined threshold value Va continues for a predetermined reference period Tb or more (step S142).

  When the period in which deviation ΔVL exceeds predetermined threshold value Va continues for a predetermined reference time Tb or more (in the case of YES in step S142), SMR welding determination unit 162 indicates that system main relays SMR1, SMR2 are welded. The determination is made and the determination flag F2 is reset to “0” (step S18).

  On the other hand, when the period during which deviation ΔVL exceeds predetermined threshold Va is shorter than predetermined reference time Tb (NO in step S142), SMR welding determination unit 162 further determines voltage command value VL *. It is determined whether or not has reached the voltage V2 (step S143). If voltage command value VL * has not reached voltage V2 (NO in step S143), the process returns to step S120.

  On the other hand, when voltage command value VL * has reached voltage V2 (YES in step S143), SMR welding determination unit 162 determines that system main relays SMR1 and SMR2 are normal, and determination flag F2 Is set to "1" (step S17).

  Finally, the SMR welding determination unit 162 determines whether or not the determination flag F2 is “1” (step S19). When determination flag F2 is “1” (YES in step S19), SMR welding determination unit 162 determines that system main relays SMR1, SMR2 are normal, and sets SMR determination flag FSMR to “1”. (Step S20).

  When HV control unit 160 receives SMR determination flag FSMR, HV control unit 160 generates an operation command for motor generators MG1 and MG2 for causing hybrid vehicle 100 to travel in a battery-less manner, and sends it to MGECU 140. Thereby, the hybrid vehicle 100 performs battery-less traveling (step S21).

  On the other hand, when determination flag F2 is not “1” (that is, “0”) (NO in step S19), SMR welding determination unit 162 causes system main relays SMR1 and SMR2 to weld. SMR determination flag FSMR is reset to “0” (step S22).

  When receiving the SMR determination flag FSMR, the HV control unit 160 causes the hybrid vehicle 100 to transition from the Ready state in which the vehicle is permitted to travel to the off state. As a result, the hybrid vehicle 100 stops traveling (step S23).

[Embodiment 3]
FIG. 10 is a timing chart for explaining the welding determination operation of system main relays SMR1, SMR2 according to the third embodiment of the present invention.

  Referring to FIG. 10, HV control unit 160 (FIG. 3) of hybrid ECU 15 issues an SMR cutoff command at time t <b> 1 when it receives abnormality information of battery 10 detected by battery ECU 200. Converter control unit 144 (FIG. 3) of MGECU 140 generates signal SE for turning off system main relays SMR1 and SMR2 in accordance with the SMR cutoff command, and outputs the signal SE to system main relays SMR1 and SMR2.

  Further, HV control unit 160 generates a VL constant request at time t 2 and sends it to converter control unit 144. Upon receiving the VL constant request, converter control unit 144 starts VL constant control for setting DC voltage VL to voltage command value VL *.

  At this time, the SMR welding determination unit 162 of the hybrid ECU 15 intentionally changes the voltage command value VL * in the constant VL control from a preset voltage (substantially equivalent to the charge / discharge voltage Vb of the battery 10). Let

  Specifically, SMR welding determination unit 162 acquires in advance the fluctuation range of DC voltage VL when VL constant control is performed with battery 10 connected to the power supply device. In FIG. 4, the DC voltage VL has a variation range of ± ΔV centering on the charge / discharge voltage Vb of the battery 10. The voltage V1 in the figure indicates the lower limit value (Vb−ΔV) of the fluctuation range, and the voltage V2 indicates the upper limit value (Vb + ΔV) of the fluctuation range.

  SMR welding determination unit 162 sets two voltage command values VL * based on the fluctuation range of DC voltage VL. One voltage command value VL * is set to a voltage lower than the voltage V1 that is the lower limit value, and the other voltage command value VL * is set to a voltage that is higher than the voltage V2 that is the upper limit value. The SMR welding determination unit 162 switches these two voltage command values VL * at least once. For example, in the case of FIG. 10, the voltage command value VL * is switched once.

  SMR welding determination unit 162 then includes system main relays SMR1, SMR2 based on DC voltage VL detected by voltage sensor 120 when converter 110 performs a step-down operation according to each of two voltage command values VL *. Determine welding.

  Specifically, when a VL constant request is issued at time t2, SMR welding determination unit 162 first sets voltage command value VL * to a voltage lower than voltage V1 in period T1 from time t2 to time t4. Set to. Thereby, converter 110 performs a step-down operation of motor operating voltage VH so that DC voltage VL becomes voltage command value VL * (<V1).

  At this time, the SMR welding determination unit 162 samples the detection value of the voltage sensor 120 at a predetermined sampling period in a period from time t20 to time t4 after a predetermined period T01 has elapsed from time t2. Then, the SMR welding determination unit 162 calculates an average value VL1 of a plurality of sampling values (corresponding to the circles in the figure), and stores the calculated average value VL1 in a predetermined storage area. The predetermined period T01 is set so as to be equal to or longer than the time required for the DC voltage VL to coincide with the voltage command value VL * in consideration of the control response of the converter 110.

  Next, SMR welding determination unit 162 sets voltage command value VL * to a voltage higher than voltage V2 during the period from time t4 to time t6. Thereby, converter 110 performs a step-down operation of motor operating voltage VH so that DC voltage VL becomes voltage command value VL * (> V2).

  At this time, the SMR welding determination unit 162 sets the detection value of the voltage sensor 120 to a predetermined value during a period (= T2-T1) from time t21 to time t6 after a predetermined period (= T02−T1) has elapsed since time t6. Sampling is performed at the sampling period. Then, the SMR welding determination unit 162 calculates an average value VL2 of a plurality of sampling values (corresponding to circles in the figure), and stores the calculated average value VL2 in a predetermined storage area. Note that the predetermined period (= T02−T1) is set to be equal to or longer than the time required for the DC voltage VL to coincide with the voltage command value VL * in consideration of the control response of the converter 110.

  Finally, after time t6, the SMR welding determination unit 162 reads the average values VL1 and VL2 stored in the predetermined storage area, and calculates the deviation ΔVL1 (= | VL1-VL2 |) of these two average values. . Based on the calculated deviation ΔVL1, the welding of the system main relays SMR1, SMR2 is determined.

  At this time, when the system main relays SMR1 and SMR2 are not welded, the DC voltage VL changes to a voltage lower than the voltage V1 following the voltage command value VL * as shown by the line LN1, The voltage changes to a voltage higher than the voltage V2. Therefore, the deviation ΔVL1 calculated from the two average values VL1 and VL2 of the DC voltage VL is larger than the fluctuation range (= | V2−V1 |) of the DC voltage VL when the battery 10 is connected. .

  On the other hand, when system main relays SMR1 and SMR2 are welded, DC voltage VL does not follow voltage command value VL * as shown by line LN2, and battery 10 is connected. Fluctuates within the fluctuation range of the DC voltage VL at Therefore, the deviation ΔVL1 calculated from the two average values VL1 and VL2 of the DC voltage VL is equal to or less than the fluctuation range (= | V2−V1 |) of the DC voltage VL when the battery 10 is connected.

  Therefore, SMR welding determination section 162 determines that system main relays SMR1 and SMR2 are not welded when calculated deviation ΔVL1 is larger than the fluctuation range (= | V2−V1 |). At this time, the SMR welding determination unit 162 sets the SMR determination flag FSMR to “1” as indicated by the line LN23.

  On the other hand, when the calculated deviation ΔVL1 is equal to or less than the fluctuation range (= | V2−V1 |), it is determined that the system main relays SMR1 and SMR2 are welded. In this case, the SMR welding determination unit 162 resets the SMR determination flag FSMR to “0” as indicated by a line LN24.

The above processing can be summarized in a processing flow as shown in FIGS.
(flowchart)
FIGS. 11 and 12 are flowcharts illustrating a processing procedure for welding determination operation of system main relays SMR1, SMR2 by hybrid ECU 15 according to the third embodiment of the present invention. The processing of each step shown in FIGS. 11 and 12 is realized by the hybrid ECU 15 (FIG. 2) functioning as each control block shown in FIG.

  Referring to FIG. 11, when hybrid ECU 15 that functions as HV control unit 160 detects an abnormality of battery 10 based on the abnormality information from battery ECU (step S01), it issues an SMR cutoff command (step S02). The HV control unit 160 further issues a VL constant request (step S03). Thereby, in converter 110, VL constant control is started.

  Next, the hybrid ECU 15 functioning as the SMR welding determination unit 162 sets the voltage command value VL * in the VL constant control to a voltage lower than the voltage V1 (step S04). The timer 164 measures an elapsed time (elapsed time after request) t after the VL constant request is issued (step S05). The SMR welding determination unit 162 acquires the elapsed time t after the request timed by the timer 164.

  Then, the SMR welding determination unit 162 determines whether or not the post-request elapsed time t has exceeded a predetermined period T01 (step S051). Note that the predetermined period T01 is set in advance in consideration of the control responsiveness of the converter 110 as shown in FIG. If elapsed time after request t is equal to or shorter than predetermined period T01 (NO in step S051), the process returns to step S051.

  On the other hand, when the post-request elapsed time t exceeds the predetermined period T01 (YES in step S051), the SMR welding determination unit 162 acquires the DC voltage VL from the voltage sensor 120 (step S06). . Then, the SMR welding determination unit 162 samples the detection value of the voltage sensor 120 at a predetermined sampling period, and calculates an average value VL1 of the plurality of sampling values (step S062).

  At this time, the SMR welding determination unit 162 determines whether or not the post-request elapsed time t has exceeded a predetermined determination period T1 (step S07). If elapsed time after request t is equal to or shorter than predetermined determination period T1 (NO in step S07), the process returns to step S062.

  On the other hand, when the post-request elapsed period t exceeds the predetermined determination period T1 (YES in step S07), the SMR welding determination unit 162 determines the average value VL1 at this time as the final average The value VL1 is determined and stored in a predetermined storage area (step S082).

  Next, SMR welding determination unit 162 sets voltage command value VL * to a voltage higher than voltage V2 (step S12). The timer 164 measures the elapsed time t after the request (step S13). The SMR welding determination unit 162 acquires the elapsed time t after the request timed by the timer 164.

  Then, the SMR welding determination unit 162 determines whether or not the post-request elapsed time t has exceeded a predetermined period T02 (step S130). Note that the predetermined period T02 is set in advance in consideration of the control response of the converter 110 as shown in FIG. If elapsed time t after request is equal to or shorter than predetermined period T02 (NO in step S130), the process returns to step S130.

  On the other hand, when the elapsed time t after the request exceeds the predetermined period T02 (YES in step S130), the SMR welding determination unit 162 acquires the DC voltage VL from the voltage sensor 120 (step S14). . Then, the SMR welding determination unit 162 samples the detection value of the voltage sensor 120 at a predetermined sampling period, and calculates an average value VL2 of the plurality of sampling values (step S144).

  At this time, the SMR welding determination unit 162 determines whether the post-request elapsed time t has exceeded a predetermined determination period T2 (step S15). If elapsed time after request t is equal to or shorter than predetermined determination period T2 (NO in step S15), the process returns to step S144.

  On the other hand, when the post-request elapsed period t exceeds the predetermined determination period T2 (in the case of YES in step S15), the SMR welding determination unit 162 determines the average value VL2 at this time as the final average The value VL2 is determined and stored in a predetermined storage area (step S151).

  Finally, the SMR welding determination unit 162 reads the average values VL1 and VL2 stored in the predetermined storage area, and calculates a deviation ΔVL1 (= | VL1−VL2 |) between these two average values (step S152). Then, it is determined whether or not the calculated deviation ΔVL1 is larger than the fluctuation range (= | V2−V1 |) of the DC voltage VL when the battery 10 is connected (step S153).

  When the calculated deviation ΔVL1 is larger than the fluctuation range (= | V2-V1 |), the SMR welding determination unit 162 determines that the system main relays SMR1 and SMR2 are normal, and sets the SMR determination flag FSMR to “ 1 "(step S20).

  When HV control unit 160 receives SMR determination flag FSMR, HV control unit 160 generates an operation command for motor generators MG1 and MG2 for causing hybrid vehicle 100 to travel in a battery-less manner, and sends it to MGECU 140. Thereby, the hybrid vehicle 100 performs battery-less traveling (step S21).

  On the other hand, when the calculated deviation ΔVL1 is equal to or less than the fluctuation range (= | V2−V1 |), it is determined that the system main relays SMR1 and SMR2 are welded, and the SMR determination flag FSMR is reset to “0”. (Step S22).

  When receiving the SMR determination flag FSMR, the HV control unit 160 causes the hybrid vehicle 100 to transition from the Ready state in which the vehicle is in the travel permitted state − to the off state. As a result, the hybrid vehicle 100 stops traveling (step S23).

  Regarding the correspondence between the first to third embodiments of the present invention and the present invention, the HV control unit 160 and the MGECU 140 correspond to a “control device”, and the SMR welding determination unit 162 corresponds to a “welding determination device”. . In the control structure of the hybrid ECU 15 shown in FIG. 3, the SMR welding determination unit 162 realizes “first setting means”, “second setting means”, “acquisition means”, and “welding determination means”. Each functional block constituting these means has been described as functioning as software realized by a CPU (Central Processing Unit) that is a hybrid ECU 15 executing a program stored in a storage area. It may be realized by hardware. Such a program is recorded on a recording medium and mounted on the vehicle.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be applied to a power supply device mounted on a hybrid vehicle.

1 is a block diagram illustrating a configuration of a vehicle equipped with a power supply device according to a first embodiment of the present invention. It is a block diagram which shows the structure of the power supply device by this invention. FIG. 4 is a block diagram showing a control structure in hybrid ECU 15 according to the embodiment of the present invention. It is a timing chart for explaining the welding determination operation of system main relays SMR1, SMR2 according to the first embodiment of the present invention. FIG. 6 is a flowchart illustrating a processing procedure for welding determination operation of system main relays SMR1, SMR2 by hybrid ECU 15 according to the first embodiment of the present invention. FIG. 6 is a flowchart illustrating a processing procedure for welding determination operation of system main relays SMR1, SMR2 by hybrid ECU 15 according to the first embodiment of the present invention. It is a timing chart for demonstrating the welding determination operation | movement of system main relays SMR1 and SMR2 according to Embodiment 2 of this invention. It is a flowchart explaining the process sequence of the welding determination operation | movement of system main relays SMR1 and SMR2 by hybrid ECU15 according to Embodiment 2 of the present invention. It is a flowchart explaining the process sequence of the welding determination operation | movement of system main relays SMR1 and SMR2 by hybrid ECU15 according to Embodiment 2 of the present invention. It is a timing chart for demonstrating the welding determination operation | movement of system main relays SMR1 and SMR2 according to Embodiment 3 of this invention. It is a flowchart explaining the process sequence of the welding determination operation | movement of system main relay SMR1, SMR2 by hybrid ECU15 according to Embodiment 3 of the present invention. It is a flowchart explaining the process sequence of the welding determination operation | movement of system main relay SMR1, SMR2 by hybrid ECU15 according to Embodiment 3 of the present invention.

Explanation of symbols

  10 battery, 15 hybrid ECU, 17 various sensor outputs, 30 power output device, 35 accelerator pedal, 50L, 50R front wheel, 60L, 60R rear wheel, 70L, 70R front seat, 80 rear seat, 100 hybrid vehicle, 101, 103 power line , 102 Earth line, 110 converter, 120, 122 voltage sensor, 130 DC / DC converter, 131, 132 inverter, 140 MGECU, 142 inverter control unit, 144 converter control unit, 160 HV control unit, 162 SMR welding determination unit, 164 Timer, 200 Battery ECU, C1, C2 capacitor, D1-D8 diode, ENG engine, MG1, MG2 Motor generator, PSD Power split mechanism, Q1-Q8 Switchon Element, SB auxiliary battery, SMR1, SMR2 system main relay.

Claims (14)

A power supply capable of supplying a DC voltage to the first and second power supply lines;
A relay for connecting and disconnecting between the power source and the first and second power lines;
A voltage converter that performs voltage conversion between the first and second power supply lines and the electric load according to a voltage command value;
A control device for controlling operation when the electric load is abnormal by shutting off the relay when an abnormality of the power source is detected;
In the operation at the time of abnormality of the electric load, comprising a welding determination device that determines welding of the relay,
The control device includes voltage conversion control means for converting the generated power at the electric load according to the voltage command value and outputting the voltage between the first and second power supply lines,
The welding determination device includes:
A variation range of output voltage output between the first and second power supply lines when the voltage conversion is performed in a state where the power supply and the first and second power supply lines are connected is previously provided, First setting means for setting the voltage command value to a first voltage that is equal to or lower than a lower limit value of the fluctuation range;
Second setting means for setting the voltage command value to a second voltage that is equal to or higher than the upper limit value of the fluctuation range;
Switching means for performing switching between the first setting means and the second setting means at least once;
Obtaining means for obtaining an output voltage output between the first and second power supply lines during execution of the voltage conversion control means;
A power supply apparatus comprising: a welding determination unit that determines welding of the connection portion based on the acquired relationship between the output voltage and the voltage command value. The welding determination means includes
First determination means for determining welding of the relay when the voltage command value is the first voltage;
And second determination means for determining welding of the relay when the voltage command value is the second voltage,
2. The power supply according to claim 1, wherein in each of the first determination unit and the second determination unit, when the relay is not welded and is determined to be normal, the connection unit is determined to be normal. apparatus. The first setting means sets the first voltage to a voltage lower than a lower limit value of the fluctuation range,
The second setting means sets the second voltage to a voltage higher than the upper limit value of the fluctuation range,
When the voltage command value is the first voltage, the first determination unit determines that the relay is normal when the output voltage continues below a lower limit value of the fluctuation range for a predetermined period or longer. Judge that there is,
When the voltage command value is the second voltage, the second determination means determines that the relay is normal when the output voltage exceeds the upper limit value of the fluctuation range for a predetermined period or longer. The power supply device according to claim 2, wherein the power supply device is determined to be present.   The power supply apparatus according to claim 1, wherein the welding determination unit determines welding of the relay based on a deviation between the output voltage and the voltage command value. The first setting means sets the first voltage to a lower limit value of the fluctuation range,
The second setting means sets the second voltage to an upper limit value of the fluctuation range,
The switching means changes the voltage command value from the first voltage to the second voltage at a predetermined rate of change,
When the voltage command value is the first voltage, the first determination unit, when a period in which a deviation between the output voltage and the voltage command value exceeds a predetermined threshold continues for a predetermined period or longer, It is determined that the relay is welded,
When the voltage command value is changing at the predetermined change rate, the second determination means has a period in which a deviation between the output voltage and the voltage command value exceeds a predetermined threshold for a predetermined period or longer. The power supply device according to claim 4, wherein the relay determines that the relay is welded.   The power supply apparatus according to claim 5, wherein the predetermined change rate is set based on a control response of the voltage conversion control unit. The first setting means sets the first voltage to a voltage lower than a lower limit value of the fluctuation range,
The second setting means sets the second voltage to a voltage higher than the upper limit value of the fluctuation range,
The welding determination means includes
First computing means for computing an average value of the output voltages acquired when the voltage command value is the first voltage;
Second computing means for computing an average value of the output voltages acquired when the voltage command value is the second voltage;
Determining means for determining that the relay is not welded and is normal when the deviation of the average value calculated by each of the first and second calculating means exceeds the fluctuation range; The power supply device according to claim 1. A method for determining welding of a relay in a power supply device,
The power supply device
A power supply capable of supplying a DC voltage to the first and second power supply lines;
A relay for connecting and disconnecting between the power source and the first and second power lines;
A voltage converter that performs voltage conversion between the first and second power supply lines and the electric load according to a voltage command value;
When the abnormality of the power source is detected, cutting off the relay and controlling the operation when the electric load is abnormal;
In the operation when the electric load is abnormal, the step of determining welding of the relay,
The step of controlling the operation when the electric load is abnormal includes the step of converting the generated power at the electric load according to the voltage command value and outputting the voltage between the first and second power lines.
The step of determining welding of the relay includes
A variation range of output voltage output between the first and second power supply lines when the voltage conversion is performed in a state where the power supply and the first and second power supply lines are connected is previously provided, Setting the voltage command value to a first voltage that is less than or equal to a lower limit value of the fluctuation range;
Setting the voltage command value to a second voltage that is not less than the upper limit value of the fluctuation range;
Performing at least one switch between setting to the first voltage and setting to the second voltage;
Obtaining an output voltage output between the first and second power supply lines during execution of the voltage conversion;
A relay welding determination method, comprising: determining the relay welding based on the acquired relationship between the output voltage and the voltage command value. The step of determining welding of the relay includes
Determining the welding of the relay when the voltage command value is the first voltage;
Determining the welding of the relay when the voltage command value is the second voltage;
When the voltage command value is the first voltage and when the voltage command value is the second voltage, the relay is normal when it is determined that the relay is not welded and is normal. The relay welding determination method according to claim 8, further comprising a step of determining that The step of setting the voltage command value to the first voltage sets the first voltage to a voltage lower than a lower limit value of the fluctuation range,
The step of setting the voltage command value to the second voltage sets the second voltage to a voltage higher than the upper limit value of the fluctuation range,
When the voltage command value is the first voltage, the step of determining welding of the relay is performed when the relay voltage is maintained when a period during which the output voltage falls below a lower limit value of the fluctuation range continues for a predetermined period or longer. Determine that it is normal,
When the voltage command value is the second voltage, the step of determining the welding of the relay is performed when the relay voltage exceeds the upper limit value of the fluctuation range for a predetermined period or longer. The relay welding determination method according to claim 9, wherein the relay is determined to be normal.   The relay welding determination method according to claim 8, wherein the step of determining the welding of the relay determines the welding of the relay based on a deviation between the output voltage and the voltage command value. The step of setting the voltage command value to the first voltage sets the first voltage to a lower limit value of the fluctuation range,
The step of setting the voltage command value to the second voltage sets the second voltage to an upper limit value of the fluctuation range,
The switching means changes the voltage command value from the first voltage to the second voltage at a predetermined rate of change,
When the voltage command value is the first voltage, the step of determining welding of the relay is performed when a period in which a deviation between the output voltage and the voltage command value exceeds a predetermined threshold continues for a predetermined period or longer. To determine that the connecting portion is welded,
When the voltage command value is the second voltage, the step of determining welding of the relay includes the output voltage and the voltage command when the voltage command value is changing at the predetermined rate of change. The relay welding determination method according to claim 11, wherein the relay is determined to be welded when a period in which a deviation from a value exceeds a predetermined threshold continues for a predetermined period or longer.   The relay welding determination method according to claim 12, wherein the predetermined change rate is set based on control responsiveness of the voltage conversion control means. The step of setting the voltage command value to the first voltage sets the first voltage to a voltage lower than a lower limit value of the fluctuation range,
The step of setting the voltage command value to the second voltage sets the second voltage to a voltage higher than the upper limit value of the fluctuation range,
The step of determining welding of the relay includes
Calculating an average value of the output voltages acquired when the voltage command value is the first voltage;
Calculating an average value of the output voltages acquired when the voltage command value is the second voltage;
The deviation between the average value calculated when the voltage command value is the first voltage and the average value calculated when the voltage command value is the second voltage exceeds the fluctuation range. The relay welding determination method according to claim 8, further comprising: determining that the relay is not welded and is normal.

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