JP4570859B2 - Relay welding detection device and relay welding detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a welding detection device capable of determining which relay of the plus side or the minus side of a battery is broken without adding any specific circuit such as a welding detection circuit. <P>SOLUTION: The relay welding detection device changes a state that the plus side relay and minus side relay are turned on and a pre-charge relay connected in parallel to the plus side relay is turned off into a first state that the plus side relay and the pre-charge relay are turned off and the minus side relay is turned on. It is determined that the plus side relay is welded in the case that a value of the load circuit side voltage at the first state does not deviate by more than a first value set in advance after the passage of a preset first period. It is determined that the minus side relay is welded in the case that, when the first state is changed into a second state in which the plus side relay and the minus side relay are turned off and the pre-charge relay is turned on, and the value of the load circuit side voltage at the second state does not deviate by more than a second value set in advance after the passage of a preset second period. <P>COPYRIGHT: (C)2005,JPO&amp;NCIPI

Description

  The present invention relates to a relay welding detection device and a relay welding detection method, and more particularly to a relay welding detection device and a relay welding detection method for detecting welding of a relay connecting a battery and a load circuit.

  Conventionally, a relay is generally used to control power supply from a high voltage battery or the like to a motor or the like. For example, in an electric vehicle, a hybrid vehicle, etc., in order to control power supply from a high voltage battery to a high voltage system circuit component, a relay is provided between the battery and the high voltage system circuit component, and the high voltage system circuit component The connection and release of the battery and the battery are performed by a relay according to the vehicle control state.

  In such a case, the relay may be welded due to an overcurrent or the like. Therefore, in order to detect the welding of the relay, the photocoupler connected in series with each relay and the photodiode lights up when the relay is opened. The welding detection of the relay is performed by adding a welding detection circuit having a circuit for detecting whether or not the relay is operating to the relay.

However, adding a welding detection circuit dedicated for relay welding detection has problems such as cost and installation space, so in order to solve such problems, without adding equipment such as a special circuit, A method of diagnosing a relay failure has been proposed (see, for example, Patent Document 1).
JP-A-10-144194 (paragraph numbers 13 to 20, FIGS. 1 to 4)

  According to the proposal, although it is possible to diagnose whether or not the relay has failed without adding a device such as a special circuit, in the proposal, the + (plus) side relay and the-(minus) side relay of the battery are proposed. It was not possible to identify which of the two had a welding failure. If it becomes clear which of the + (plus) side relay and the-(minus) side relay is welded, it is possible to quickly perform repairs and the like.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a welding detection device capable of diagnosing whether the relay on the + side or the − side of the battery has failed without adding a dedicated circuit such as a welding detection circuit. .

Relay welding detecting device of the present invention is connected between the load circuit and the battery, and the + side relays being connected to the positive side of the battery, the battery - are connected to the side - detecting the welding of the side relay The positive-side relay and the negative-side relay are both on, and the pre-charge relay of a series circuit including a pre-charge relay and a pre-charging resistor provided in parallel to the positive-side relay is off. The first state changing means for changing from the state to the first state in which the + side relay and the precharge relay are off and the-side relay is on, and the load in the first state A first welding determination means for determining that the + side relay is welded when a voltage value on the circuit side does not change more than a predetermined first value after elapse of a predetermined first time; and First Second state changing means for changing from the state to the second state in which the + side relay and the-side relay are off and the precharge relay is on, and the load in the second state A second welding determination means for determining that the negative relay is welded when the voltage value on the circuit side does not change by a predetermined second value after a predetermined second time has elapsed; .

  ADVANTAGE OF THE INVENTION According to this invention, the welding detection apparatus which can diagnose whether the relay of + side or-side of a battery has failed can be implement | achieved, without adding dedicated circuits, such as a welding detection circuit.

Hereinafter, a relay welding detection apparatus according to an embodiment of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a configuration diagram showing the configuration of a vehicle drive system according to the first embodiment.
The vehicle according to the present embodiment is a parallel hybrid vehicle that uses both an engine and a motor. As shown in FIG. 1, the engine 1 and the first motor that is responsible for starting the engine 1 and for generating power and assisting power. 2 (hereinafter simply referred to as the motor 2), the planetary gear unit 3 connected to the output shaft 1a of the engine 1 via the motor 2, and the functions of the planetary gear unit 3 are controlled to serve as a driving force source for starting and reverse driving. And a drive system having a basic configuration of a second motor 4 (hereinafter simply referred to as the motor 4) responsible for recovery of deceleration energy and a power conversion mechanism 5 that performs speed change and torque amplification to perform a power conversion function during traveling. It has.

  The planetary gear unit 3 is a single-pinion planetary gear having a sun gear 3a, a carrier 3b that rotatably supports a pinion that meshes with the sun gear 3a, and a ring gear 3c that meshes with the pinion. Further, as the power conversion mechanism 5, a transmission using a combination of gear trains, a transmission using a fluid torque converter, or the like can be used. However, a primary pulley 5b and an output shaft 5c that are supported by the input shaft 5a. It is desirable to employ a belt-type continuously variable transmission (CVT) formed by winding a drive belt 5e between the secondary pulley 5d and the secondary pulley 5d. In the present embodiment, hereinafter, a power conversion mechanism 5 is used. Will be described as CVT5.

  That is, in the hybrid vehicle drive system in the present embodiment, planetary gear unit 3 is arranged between output shaft 1a of engine 1 and input shaft 5a of CVT 5. The ring gear 3c of the planetary gear unit 3 is coupled to the output shaft 1a of the engine 1 via one motor 2, the carrier 3b is coupled to the input shaft 5a of the CVT 5, and the other motor 4 is coupled to the sun gear 3a. Yes. A differential mechanism 7 is connected to the output shaft 5 c of the CVT 5 via a reduction gear train 6, and front wheels or rear wheel drive wheels 9 are connected to the differential mechanism 7 via a drive shaft 8.

  The motors 2 and 4 are connected to an inverter 10, and a battery 11 is connected to the inverter 10. The inverter 10 which is a load circuit of the battery 11 receives supply of AC power from the motors 2 and 4 and charges the battery 11 or receives supply of DC power from the battery 11 and drives the motors 2 and 4. .

Positive side of the battery 11 (hereinafter, referred to as + side) through the + side relay 1 2 of the main relay is connected to the inverter 10. The negative side (hereinafter, abbreviated as “−”) of the battery 11 is connected to the inverter 10 via the negative relay 13 of the main relay. Further, a precharge relay 14 is connected in parallel to the + side relay 12.

  The vehicle control unit 15 controls on / off of the + side relay 12, the − side relay 13, and the precharge relay 14. The inverter 10 is controlled by the inverter control unit 16. An output signal of a voltmeter 17 that measures the terminal voltage of the inverter 10 is input to the inverter control unit 16, and the inverter control unit 16 performs data communication with the vehicle control unit 15. Therefore, the inverter control unit 16 performs control of conversion between direct current and alternating current, control of the rotational speed of the motor, and the like according to the output of the voltmeter 17 and the control state of the vehicle. The voltmeter 17 may be a normal voltmeter that directly measures a voltage, or may be an apparatus that indirectly measures a voltage by converting the voltage into a light amount or the like.

  The vehicle control unit 15 includes a central processing unit (hereinafter referred to as a CPU), a read only memory (ROM), a random access memory (RAM), and various interfaces. By executing a predetermined program stored in the ROM by the CPU, the vehicle control unit 15 can realize various functions including welding detection described later.

  The precharge relay 14 is a relay that is turned on before the + side relay 12 is turned on in order to prevent a high voltage from being suddenly applied to the + side relay 12 when the battery 11 and the inverter 10 are connected. A precharge resistor 18 is connected in series with the precharge relay 14. A series circuit including the precharge relay 14 and the resistor 18 is provided in parallel to the + side relay 12. Therefore, when the + side relay 12 is turned on, the precharge relay 14 is first turned on, and then the + side relay 12 is turned on, so that a high voltage is not suddenly applied to the + side relay 12. it can.

  The engine 1, the two motors 2, 4, and the CVT 5 are centrally controlled by the vehicle control unit 15. The vehicle control unit 15 monitors the operating state of the engine 1, the two motors 2, 4 and the CVT 5, and the state of the battery 11, and operates the ignition key by the driver, depressing the accelerator pedal and the brake pedal, steering the steering, etc. Based on the information, the engine 1 is controlled, the motors 2 and 4 are driven through the inverter 10, the battery 11 is charged, the gear ratio of the CVT 5 and the supply hydraulic pressure are controlled.

In the drive system configured as described above, as described above, the engine 1 and the motor 2 are coupled to the ring gear 3c of the planetary gear unit 3, and the motor 4 is coupled to the sun gear 3a to obtain an output from the carrier 3b. Since the output from 3b is shifted and amplified by the CVT 5 and transmitted to the drive wheels 9, the two motors 2 and 4 can be used for both power generation and drive power supply and are relatively small. An output motor can be used. Next, a relay welding detection method according to the present embodiment will be described.

The detection of relay welding is performed by the vehicle control unit 15 when the vehicle is stopped, in other words, when the ignition key is turned off. More specifically, the welding detection of the relay is performed when the connection between the battery 11 and the inverter 10 that is a high voltage system circuit is disconnected (when the battery 11 and the inverter 10 are disconnected from the connected state). Then, before the terminal voltage of the inverter 10 drops, the welding of the relay is detected while the relay is turned on and off in a predetermined control sequence. Relay welding detection is performed by the CPU of the vehicle control unit 15 executing a relay welding detection program stored in the ROM.
Incidentally, when the vehicle engine is started, in other words, when the ignition key is turned on, the -side relay 13, the precharge relay 14, and the + side relay 12 are turned on in this order, and then the precharge relay 14 is turned off. As a result, power supply from the battery 11 is started.

The process for detection of welding will be described with reference to FIGS.
FIG. 2 is a diagram for explaining a relay control sequence of the + side relay 12, the −side relay 13 and the precharge relay 14 when welding is detected. FIG. 3 is a flowchart showing an example of the flow of welding detection processing.
When the vehicle is in an operating state, the inverter 10 and the battery 11 that are high voltage system circuits are in a connected state. Therefore, as shown in the high voltage system circuit connected state in FIG. The side relay 13 is on and the precharge relay 14 is off.

When the driver turns the ignition key to stop vehicle control (hereinafter referred to as vehicle control stop), the processing of FIG. 3 is executed.
When the vehicle control is stopped, the vehicle control unit 15 first outputs an off control signal to the + side relay 12 to turn off the + side relay 12 of the main relay (step (hereinafter abbreviated as S) 1). Change the relay connection status. At this time, as shown in the welding determination state (1) in FIG. 2, in each relay, the + side relay 12 is off, the − side relay 13 remains on, and the precharge relay 14 is off (hereinafter referred to as “relay determination state”). , Also referred to as the first state).

Next, in the first state, it is determined whether or not the voltage value output from the voltmeter 17 is equal to or lower than a preset threshold value TH1a (S2). When the + side relay 12 is welded, the voltage value output from the voltmeter 17 does not decrease with time even if the + side relay 12 is about to be turned off by the control signal from the voltage control unit 15. Therefore, if the voltage value output from the voltmeter 17 does not change more than a predetermined value due to a voltage drop after a predetermined time has elapsed, it is determined that the + side relay 12 is welded, NO is determined in S2, an abnormal process is performed (S3), and the process ends. Note that after the process of S3, the process may proceed to the process of S4 as shown by the dotted arrow in FIG.
If + have side relay 12 is welded, the control signal from the voltage control unit 15, the + side relay 12 since the off or open, the voltage value output from the voltmeter 17, decreases with time. Therefore, the voltage value output from the voltmeter 17, after a predetermined time has elapsed, if there is a predetermined value or more changes the voltage drop, positive side relay 12 is determined not to be welded, YES in S2, and the process proceeds to S4.

  Next, in S4, the negative relay 13 is turned off and the precharge relay 14 is turned on (S4), thereby changing the connection state of the relay. At this time, as shown in the welding determination state (2) in FIG. 2, in each relay, the + side relay 12 remains off, the − side relay 13 is off, and the precharge relay 14 is on (hereinafter, (Also called the second state).

Next, in the second state, it is determined whether or not the voltage value output from the voltmeter 13 has become equal to or less than a preset threshold TH 1b within a predetermined time (S5). When the negative relay 13 is welded, the voltage value output from the voltmeter 17 does not decrease with time even if the negative relay 13 is turned off by a control signal from the voltage control unit 15. Therefore, the voltage value output from the voltmeter 17 is a value determined in advance by a voltage drop after a predetermined time has elapsed (this value may be the same as or different from the predetermined value in S3 described above). If the above change does not occur, it is determined that the negative relay 13 is welded, NO is determined in S5, an abnormal process is performed (S6), and the process ends.

  In the abnormality process of S3 and S6, a failure code indicating the content of the abnormality (welding failure) is displayed in the warning display unit mounted on the vehicle in the welding state, and the failure code indicating the failure state is stored in the nonvolatile memory in the vehicle control unit 15. Processing such as recording in a predetermined storage area is performed. When a vehicle maintenance man performs vehicle check, maintenance, etc., it can know which relay is welded by displaying on a warning display unit or a failure diagnosis device based on data in a nonvolatile memory. If possible, it will help prevent accidents such as electric shock. Further, in the abnormality processing, the relay control may be limited so that the ON signal to the main relay is not output even if the ignition key is turned on next time.

  If the -side relay 13 is not welded, the -side relay 13 is turned off, that is, opened by a control signal from the voltage control unit 15, so that the voltage value output from the voltmeter 17 decreases with time. Therefore, if the voltage value output from the voltmeter 17 changes more than a predetermined value due to a voltage drop after a predetermined time has elapsed, it is determined that the negative relay 13 is not welded, and S5 Yes, and the process proceeds to S7.

In S7, since both the + side relay 12 and the -side relay 13 are not welded, normal processing is performed. This normal processing does not have to be executed, but data indicating that it is normal, for example, a code indicating normality together with time data is recorded in the nonvolatile memory of the vehicle control unit 15 or the like. May be.

Then, the process ends, and as a result, all relays, that is, control signals for connecting the + side relay 12, the − side relay 13 and the precharge relay 14 are not output. Becomes open.
Thus, the main relay + side relay 1 2 - it is possible to detect which of the side relay 13 is welded failure. In particular, since the + side relay is easily welded, the + side relay is checked before the − side relay.

The threshold values TH1a and TH1b described above are adjusted and set so as to shorten the welding determination time.
Furthermore, some inverters have a function of forcibly discharging in response to a voltage drop. In the case of an inverter having such a function, control is performed so that the discharge is stopped during welding determination. May be.

As described above, the hybrid vehicle according to the present embodiment includes the + side relay 12, the − side relay 13, the precharge relay 14, which are relays for connecting the main battery to the high voltage system circuit, and these. The vehicle control unit 15 which is a control means for controlling the relay of the inverter 10 and the voltmeter 17 which is a means for detecting the terminal voltage (voltage on the high voltage system circuit side) of the inverter 10 are included. The vehicle control unit 15 includes a program that is a means for detecting relay welding. Then, the vehicle control unit 15 controls each relay in a predetermined sequence, so that the battery is connected to the high voltage system circuit (the + side relay 12 and the −side relay 13 are both turned on) from the first state. In this state, the second state, and until all the relays are turned off, the state is changed, and the welding of the relay is detected while detecting the terminal voltage value of the inverter 10 during that time. Specifically, according to the relay control sequence shown in FIG. 2, the sequence control of the connection and release of the + side relay, the − side relay and the precharge relay is performed, and the terminal voltage of the inverter is set in advance after a predetermined time has elapsed. by determining whether or not it is below the set threshold, the + side relays of the main relay - diagnosing either side relay has failed.

Therefore, according to this embodiment, without adding detection dedicated parts such as welding detection circuit, the + side relays of the main relay - either side relay can detect whether the welded failure.

(Second Embodiment)
In the second embodiment, after the state change, the determination as to whether or not the voltage value on the load circuit side has changed by a predetermined value or more after a predetermined time has passed is made in the first embodiment. While using the relay control sequence, the amount of change in the voltage value on the high voltage system circuit side is detected, and whether or not the amount of change is equal to or greater than a predetermined threshold value is detected, so that welding of the relay is detected. Specifically, in the determination blocks of S2 and S5 in FIG. 3, instead of the determination contents in the first embodiment, the change from the detected voltage value of the voltmeter 17 immediately before the welding determination within a predetermined time. calculating the amount of the change amount, by determining whether was above a predetermined threshold, it performs the weld decision-relay.
The configuration of the vehicle drive system in the second to fifth embodiments described below is the same as the configuration of FIG. 1 of the first embodiment, and the relay control sequence for relay welding determination is shown in FIG. 2 is the same as the sequence shown in FIG. 2, and the flow of the welding determination process is also the same as the process of FIG. 3. Therefore, these descriptions are omitted, and only different items are described.

The welding detection method according to the second embodiment will be described in detail with reference to FIG.
FIG. 4 is a diagram showing an example of how the detection voltage of the voltmeter, that is, the voltage on the high voltage system circuit side changes with time. As shown in FIG. 4, until the vehicle control unit 15 turns off the + side relay 12 according to the relay control sequence of FIG. 2 (hereinafter referred to as t1), the high voltage system circuit connection state in FIG. The value of the voltage (terminal voltage of the inverter 10) v detected by the voltmeter 17 immediately before the welding determination is V1. The output voltage of the battery 11 does not completely match the rated value VT, and fluctuates within a predetermined allowable range RV. If the + side relay 12 is not welded and the state is changed to the first state, that is, if the + side relay 12 is turned off, the detection voltage v gradually decreases after t1.

In the first embodiment described above, whether or not the detected voltage v of the voltmeter 17 has become equal to or less than a predetermined threshold TH1a when a predetermined time T1 has elapsed (hereinafter referred to as t2). Is judged.
In the second embodiment, the change amount dV1 from the detected voltage value V1 of the voltmeter 17 immediately before the welding determination at time t2 when a predetermined time T1 has elapsed from time t1 is a predetermined threshold TH2a. It is determined whether it is above. When the amount of change dV1 from the detected voltage value V1 of the voltmeter 17 immediately before the welding determination state (1) is equal to or greater than a predetermined threshold TH2a, it is determined that the + side relay 12 is not welded. When the threshold value TH2a is not greater than or equal to the predetermined threshold value TH2a, it is determined that the positive relay 12 is welded.

Similarly, for the negative relay 13, the amount of change dV2 from the detected voltage value V2 of the voltmeter 17 immediately before the welding determination state (2) (hereinafter referred to as t3) is a predetermined time from t3. When T2 has elapsed (hereinafter referred to as t4), it is determined whether or not the negative relay 13 is welded based on whether or not the threshold TH2b is equal to or greater than a predetermined threshold value TH2b.
For these determinations, the amount of change is calculated and calculated in S2 and S5 in the flowchart of FIG. 2 described above, and compared with a predetermined threshold value. Alternatively, NO is determined in S5, and the abnormality process is executed. In both S2 and S5, if the amount of change is equal to or greater than a predetermined threshold value, the determination is YES and normal processing is executed. In the abnormal processing, processing such as warning of the welding state and prohibition of connection of the relay to stop the vehicle is performed.

Therefore, according to this second embodiment, like the first embodiment, without adding detection dedicated parts such as welding detection circuit, the + side relays of the main relay - either side relay It is possible to detect whether or not welding has failed. In addition, since the amount of change is obtained based on the detected voltage value of the voltmeter immediately before the welding determination and the welding determination is made, it is possible to improve the accuracy of the welding detection and shorten the determination time.

(Third embodiment)
In the third embodiment, after the state change, the determination as to whether or not the voltage value on the load circuit side has changed by a predetermined value or more after a predetermined time has passed is made in the first embodiment. By using the relay control sequence, the amount of change in the voltage value on the high voltage system circuit side from a predetermined value is detected, and it is determined whether the amount of change is equal to or greater than a predetermined threshold. Detects welding. Specifically, in the determination blocks of S2 and S5 in FIG. 3, instead of the determination contents in the first embodiment, the amount of change from a predetermined value within a predetermined time is calculated. By determining whether or not the amount of change is equal to or greater than a predetermined threshold value, relay welding is determined.
The welding determination method according to the third embodiment will be described in detail with reference to FIG.
In FIG. 4, VT is a predetermined value, for example, a rated output value of the battery 11. In the second embodiment, the amount of change dV1 from the detected voltage value V1 of the voltmeter 17 immediately before the welding determination is used, but in the third embodiment, the rated output value of the battery 11 and the like are determined in advance. The amount of change dVT from the measured value VT is used. As shown in FIG. 4, at t2, it is determined whether or not the change amount dVT is equal to or greater than a predetermined threshold value TH3a. When the change amount dVT is equal to or greater than a predetermined threshold TH3a, it is determined that the + side relay 12 is not welded. When the change amount dVT is not equal to or greater than the predetermined threshold TH3a, the + side relay 12 is welded. It is determined that

Similarly, with respect to the negative relay 13, whether or not the negative relay 13 is welded is determined based on whether or not the change amount dVT is equal to or greater than a predetermined threshold TH3b at t4. .
Therefore, according to the third embodiment, as in the first embodiment, any of the positive side relay and the negative side relay of the main relay can be used without adding a dedicated detection part such as a welding detection circuit. It is possible to detect whether a welding failure has occurred. In addition, since the amount of change is obtained based on a predetermined value and welding is determined, the accuracy of welding detection can be improved and the determination time can be shortened.

(Fourth embodiment)
In the fourth embodiment, after the state change, whether or not the voltage value on the load circuit side has changed by a predetermined value or more after a predetermined time has elapsed is determined in the first embodiment. Whether or not the amount of change in the voltage value on the high voltage system circuit side is detected using the relay control sequence, and the ratio of the change amount to the voltage value on the high voltage system circuit side immediately before the welding determination is greater than or equal to a predetermined threshold value. Is detected to detect welding of the relay. Specifically, in the determination blocks of S2 and S5 in FIG. 3, in place of the determination contents in the first embodiment, the voltage value on the high voltage system circuit side immediately before the welding determination is within a predetermined time. The ratio of the amount of change in the voltage value on the high voltage system circuit side is calculated, and it is determined whether or not the ratio is equal to or greater than a predetermined threshold value, thereby performing relay welding determination.
The welding determination method according to the fourth embodiment will be described in detail with reference to FIG.
In the second and third embodiments, the change amount dV1 from the detection voltage value V1 of the voltmeter 17 immediately before the welding determination or the change amount dVT from the predetermined value VT is used. In this embodiment, the ratio between the voltage value V1 on the high voltmeter circuit side immediately before the welding determination and the amount of change is used. That is, at time t2, it is determined whether the ratio dV1 / V1 between the voltage value V1 on the high voltmeter circuit side immediately before the welding determination and the change amount dV1 is equal to or greater than a predetermined threshold TH4a. When the ratio dV1 / V1 is equal to or greater than a predetermined threshold TH4a, it is determined that the + side relay 12 is not welded. When the ratio dV1 / V1 is not equal to or greater than the predetermined threshold TH3a, the + side relay 12 is It is determined that it is welded.

Similarly, for the negative relay 13, whether the ratio dV2 / V2 between the voltage value V2 on the high voltmeter circuit immediately before the welding determination and the variation dV2 is equal to or greater than a predetermined threshold TH4b at t4. Based on whether or not, it is determined whether or not the negative relay 13 is welded.
Therefore, according to the fourth embodiment, like the first embodiment, without adding detection dedicated parts such as welding detection circuit, the + side relays of the main relay - either side relay It is possible to detect whether or not welding has failed. In addition, since the ratio of the change amount with respect to the detected voltage value of the voltmeter immediately before the welding determination is obtained and the welding determination is made, it is possible to improve the accuracy of the welding detection and shorten the determination time.

(Fifth embodiment)
In the fifth embodiment, after the state change, the determination as to whether or not the voltage value on the load circuit side has changed by a predetermined value or more after the lapse of a predetermined time is made in the first embodiment. By detecting the amount of change of the voltage value on the high voltage system circuit side while using the relay control sequence, and determining whether the ratio of the amount of change with respect to the predetermined value is equal to or greater than a predetermined threshold, Detects relay welding. Specifically, in the determination blocks of S2 and S5 in FIG. 3, instead of the determination content in the first embodiment, the voltage value on the high voltage system circuit side with respect to a predetermined value within a predetermined time The ratio of the amount of change is calculated, and it is determined whether or not the ratio is equal to or greater than a predetermined threshold value, thereby performing relay welding determination.
The welding determination method according to the fifth embodiment will be described in detail with reference to FIG.
In the fourth embodiment, the ratio of the change amount dV1 to the detected voltage value V1 of the voltmeter 17 immediately before the welding determination is used, but in the fifth embodiment, the ratio of the change amount to a predetermined value. Is used. That is, at time t2, it is determined whether or not the ratio dVT / VT between the predetermined value VT such as the rated output of the battery and the amount of change dVT is equal to or greater than a predetermined threshold TH5a. When the ratio dVT / VT is equal to or greater than a predetermined threshold TH5a, it is determined that the + side relay 12 is not welded. When the ratio dVT / VT is not equal to or greater than the predetermined threshold TH5a, the + side relay 12 is It is determined that it is welded.

Similarly, for the negative relay 13, whether the negative relay 13 is welded or not is determined based on whether or not the ratio of the change amount to the predetermined value is equal to or greater than a predetermined threshold. judge. As a ratio, the ratio dVT1 / VT of the change dVT1 from t1 to t4 with respect to the predetermined value VT, or the ratio dVT2 of the change dVT2 from t3 to t4 with respect to the predetermined value VT / VT may be used.
Therefore, according to the fifth embodiment, as in the first embodiment, any of the positive side relay and the negative side relay of the main relay can be used without adding a detection-dedicated component such as a welding detection circuit. It is possible to detect whether a welding failure has occurred. In addition, since a welding ratio is determined by obtaining a ratio of a change amount with respect to a predetermined value as a reference, it is possible to improve the accuracy of welding detection and shorten the determination time.

(Sixth embodiment)
In the sixth embodiment, after the state change, it is determined whether or not the voltage value on the load circuit side has changed by a predetermined value or more after a predetermined time elapses. A means for detecting the voltage of the battery is provided while using the relay control sequence, and welding determination is performed using the battery voltage value and the voltage value on the high voltage system circuit side. Specifically, in S2 and S5 during the determination process of FIG. 3, the difference between the voltage value of the battery 11 and the voltage value on the high voltage system circuit side is calculated instead of the determination contents in the first embodiment. The welding determination is performed depending on whether the difference or the ratio of the difference to the battery voltage value is equal to or greater than a predetermined value.
FIG. 5 is a block diagram showing the configuration of a vehicle drive system according to the sixth embodiment. The same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. In FIG. 5, reference numeral 19 denotes a voltmeter that measures the output voltage of the battery 11. Reference numeral 20 denotes a battery voltage measurement unit that transmits battery voltage value data measured by the voltmeter 19 to the vehicle control unit 15 by data communication.

  Also in the sixth embodiment, the relay control sequence of FIG. 2 is used, and the + side relay 12, the −side relay 13 and the precharge relay 14 are controlled according to the relay control sequence. The difference dBV between the voltage value BV of the battery 11 and the voltage value v on the high voltage system circuit side, or the ratio dBV / BV of the difference dBV to the battery voltage value BV is greater than or equal to a predetermined threshold value. Perform welding determination.

At t2 in FIG. 4, it is determined whether or not the difference dBV is equal to or greater than a predetermined threshold TH6a, or whether the ratio dB / BV is equal to or greater than a predetermined threshold TH7a. When the difference dBV is greater than or equal to the predetermined threshold TH6a, or when the ratio dBV / BV is greater than or equal to the predetermined threshold TH7a, it is determined that the + side relay 12 is not welded, and the difference dBV is predetermined. When the threshold value TH6a is not greater than or equal to or when the ratio dB / BV is not equal to or greater than the predetermined threshold value TH7a, it is determined that the + side relay 12 is welded.

Similarly, for the negative relay 13, the difference dBV or the ratio dBV / BV is based on whether or not the negative threshold TH6b is equal to or higher than a predetermined threshold TH6b or higher than a predetermined threshold TH7b at t4. 13 determines whether or not it is welded.
Therefore, according to the sixth embodiment, as with the other embodiments, without adding a detection dedicated parts such as welding detection circuit, the main relay + side relays and - is any side relay It is possible to detect whether a welding failure has occurred. In addition, since the welding determination is performed by obtaining the difference from the battery voltage or the ratio of the difference to the battery voltage, the accuracy of welding detection can be improved.

  As described above, according to the above-described first to sixth embodiments, the load circuit is configured to perform on / off control of a relay according to a predetermined relay control sequence without providing a detection circuit dedicated to welding detection. By measuring the voltage value on the side, it is possible to detect which of the + side relay and the − side relay is welded. In particular, in the above-described first to sixth embodiments, it is only necessary to add a program for executing the above-described welding determination process to the program in the control device, that is, the vehicle control unit. is there.

  In the above embodiment, the parallel hybrid type vehicle has been described as an example. However, the method for detecting the welding of the relay described above is applicable to a series hybrid type or a series / parallel hybrid type vehicle. It can be applied to an electric vehicle that is not a system.

  The present invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the scope of the present invention.

It is a block diagram which shows the structure of the drive system of the vehicle concerning the 1st Embodiment of this invention. It is a figure for demonstrating the example of a relay control sequence. It is a flowchart which shows the example of the flow of a welding detection process. It is a figure which shows the example of a mode that the voltage by the side of a high voltage system circuit changes with progress of time. It is a block diagram which shows the structure of the drive system of the vehicle concerning 6th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... 1 engine, 2, 4 ... Motor, 3 ... Planetary gear unit, 5 ... Power conversion mechanism, 6 ... Reduction gear train, 7 ... Differential mechanism, 8 ... Drive Axis, 9 ... drive wheels, 10 ... inverter, 11 ... battery, 12 ... + side relay, 13 ...- side relay, 14 ... precharge relay, 15 ... vehicle Control unit, 16 ... Inverter control unit, 17, 19 ... Voltmeter, 18 ... Resistor, 20 ... Battery voltage measuring unit agent Patent attorney Susumu Ito

Claims (7)

Is connected between the load circuit and the battery, and the + side relays being connected to the positive side of the battery, the battery - are connected to the side - a device for detecting the welding of the side relay,
From the state in which the precharge relay of the series circuit composed of a precharge relay and a precharge resistor, which is provided in parallel with the + side relay and the + side relay, is off, the + First state changing means for changing to a first state in which the side relay and the precharge relay are off and the -side relay is on;
Determining a voltage value of the load circuit side in the first state, when no change predetermined first value or more and the first time after the predetermined, and welding the positive side relay First welding determination means;
A second state changing means for changing from the first state to a second state in which the + side relay and the -side relay are off and the precharge relay is on;
When the voltage value on the load circuit side in the second state does not change more than a predetermined second value after a predetermined second time has elapsed, the negative relay is determined to be welded. And a welding determination unit. Is connected between the load circuit and the battery, and the + side relays being connected to the positive side of the battery, the battery - are connected to the side - a method of detecting the welding of the side relay,
From the state in which the precharge relay of the series circuit composed of a precharge relay and a precharge resistor, which is provided in parallel with the + side relay and the + side relay, is off, the + Change to a first state where the side relay and the precharge relay are off and the -side relay is on,
Voltage value of the load circuit side in the first state, when no change the first value greater than or equal to a predetermined at the first time after the predetermined, the + side relay determines that welding ,
The first state is changed to a second state in which the + side relay and the − side relay are turned off and the precharge relay is turned on,
When the voltage value on the load circuit side in the second state does not change more than a predetermined second value after elapse of a predetermined second time, the negative relay is determined to be welded. A relay welding detection method characterized by the above. Is connected between the inverter and the battery for driving the motor in a hybrid vehicle, the + side relays being connected to the positive side of the battery, the battery - are connected to the side - an apparatus for detecting welding of the side relay There,
Based on an engine stop command in the hybrid vehicle, the + side relay and the − side relay are both turned on, and the parallel circuit is provided in parallel with the + side relay. A first state changing means for changing from a state in which the precharge relay is off to a first state in which the + side relay and the precharge relay are off and the -side relay is on;
Determining a voltage value of the load circuit side in the first state, when no change predetermined first value or more and the first time after the predetermined, and welding the positive side relay First welding determination means;
A second state changing means for changing from the first state to a second state in which the + side relay and the -side relay are off and the precharge relay is on;
When the voltage value on the load circuit side in the second state does not change more than a predetermined second value after a predetermined second time has elapsed, the negative relay is determined to be welded. And a welding determination unit. Is connected between the inverter and the battery for driving the motor in a hybrid vehicle, the + side relays being connected to the positive side of the battery, the battery - are connected to the side - in the method for detecting the welding of the side relay There,
Based on a vehicle control stop command in the hybrid vehicle, a series circuit including a precharge relay and a precharge resistor, in which both the + side relay and the − side relay are turned on and provided in parallel to the + side relay. The precharge relay is changed from the off state to the first state in which the + side relay and the precharge relay are off and the-side relay is on.
Voltage value of the load circuit side in the first state, when no change the first value greater than or equal to a predetermined at the first time after the predetermined, the + side relay determines that welding ,
The first state is changed to a second state in which the + side relay and the − side relay are turned off and the precharge relay is turned on,
When the voltage value on the load circuit side in the second state does not change more than a predetermined second value after elapse of a predetermined second time, the negative relay is determined to be welded. A relay welding detection method characterized by the above.   Whether or not the voltage value on the load circuit side in the first state has changed by a predetermined first value or more after a predetermined first time has elapsed is determined by the load in the first state. The relay welding detection apparatus according to claim 1 or 3, wherein the voltage determination on the circuit side is determined based on whether or not the voltage value is equal to or less than a predetermined first threshold value.   Whether the voltage value on the load circuit side in the first state has changed by a predetermined first value or more after the first predetermined time has elapsed is changed to the first state. The voltage value on the load circuit side immediately before or the amount of change in the voltage value on the load circuit side in the first state from a predetermined value, or the load circuit side immediately before changing to the first state Or a ratio of the voltage value on the load circuit side in the first state with respect to a predetermined voltage value or a predetermined value is determined by whether or not a ratio is equal to or higher than a predetermined second threshold value. The relay welding detection apparatus according to claim 1 or 3.   Whether or not the voltage value on the load circuit side in the first state has changed by a predetermined first value or more after a predetermined first time has elapsed is determined by whether or not the battery in the first state Or the ratio of the voltage value on the load circuit side in the first state to the output value of the battery in the first state is determined in advance. The relay welding detection device according to claim 1, wherein the relay welding detection device is determined based on whether or not the third threshold value is exceeded.

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