JP2007089240A - Fault detector of power supply circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To distinguish the cause of disconnection failure occurring in the power supply circuit for a vehicle having a precharge function. <P>SOLUTION: An ECU executes a program including a step (S130) for detecting the current value IB of a battery (S120) when precharge is started (YES at S110) and storing it as IB(ini), a step (S150) for detecting the inverter voltage value VH and the battery voltage value VB when a precharge time elapses (YES at S140), a step (S180) for determining that a power supply circuit is normal if VH≈VB (YES at S160), a step (S190) for determining that disconnection failure occurs due to a short circuit current if VH≈VB is not satisfied (NO at S160) and the IB(ini) exceeds an IB threshold (YES at S170), and a step (S200) for determining that disconnection failure occurs if VH≈VB is not satisfied (NO at S160) and the IB(ini) does not exceeds the IB threshold (NO at S170). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle equipped with a traveling motor such as an electric vehicle, a fuel cell vehicle, and a hybrid vehicle, and more particularly to an apparatus for detecting an abnormality in a power supply circuit that connects and disconnects a battery and a load.

  2. Description of the Related Art Conventionally, a hybrid vehicle including a motor that operates with electric energy in addition to an engine that operates with combustion energy is known as a driving force for vehicle travel. One type of hybrid vehicle is a parallel hybrid vehicle that uses a motor as an auxiliary drive source for assisting engine output. This parallel hybrid vehicle, for example, assists the output of the engine with a motor during acceleration and charges the battery etc. with deceleration regeneration during deceleration to ensure the remaining capacity of the battery. However, the driver's request can be satisfied. Such a hybrid vehicle includes a power drive unit in order to drive or regenerate a motor. The power drive unit includes a plurality of switching elements, and drives or regenerates the motor by current control using the switching elements. The hybrid vehicle also includes a motor control device that outputs a control signal that causes the switching elements to perform switching.

  By the way, when a short circuit occurs in the power drive unit, it is necessary to immediately stop the current control by the switching element in order to prevent the switching element in the power drive unit from being damaged. The current control by the switching element can be stopped by the motor control device. However, in this case, since a high-speed process is required to cope with the short circuit, the motor control apparatus has a large processing load. For this reason, the motor control device may not be able to perform important processing such as torque control of the motor at a required processing cycle. Further, erroneous detection may occur in detection of occurrence of a short circuit. For this reason, it is necessary to take measures against erroneous detection of a short circuit.

  Japanese Patent Laid-Open No. 2001-69601 (Patent Document 1) discloses a hybrid vehicle that can quickly stop current control by a switching element without increasing a load on a motor control device when a short circuit occurs in a power drive unit. To do. The hybrid vehicle disclosed in this publication includes an engine, a motor that operates with electric energy, a power drive unit that has a switching element and drives the motor by current control using the switching element, and controls that cause the switching element to perform switching. The power drive unit is configured to output a control signal to the switching element for a predetermined time when the temperature of the switching element is equal to or higher than a predetermined temperature or the current flowing through the power drive unit is equal to or higher than a predetermined current. The control device further includes a self-protection circuit that shuts off and outputs a signal indicating a self-protection state due to the shut-off, and the control device detects a signal from the self-protection circuit, and the self-protection state is a predetermined number of times or the self-protection state The accumulated time of It stops outputting the a control signal to.

According to this hybrid vehicle, the self-protection circuit sets the determination condition for occurrence of a short circuit such that the temperature of the switching element is equal to or higher than the predetermined temperature, or the current flowing through the power drive unit is equal to or higher than the predetermined current. When the condition is satisfied, the self-protection circuit cuts off the control signal to the switching element for a predetermined time. Thereby, when a short circuit occurs in the power drive unit, the current control by the switching element can be stopped for a predetermined time by the self-protection circuit constituting the power drive unit. Thereby, damage to the switching element due to a short circuit can be prevented. In addition, since current control can be stopped for a predetermined time without using a control device, it is possible to cope with a short circuit at high speed in a short time.
JP 2001-69601 A

The above-described hybrid vehicle is equipped with a battery that stores electric power supplied to the motor, the motor is connected to the inverter, and the inverter is connected to the battery. Between the inverter and the battery, an SMR (System Main Relay) for connecting and disconnecting the electrical connection between the inverter and the battery is provided. The SMR includes a positive SMR provided on the positive side of the battery, a negative SMR provided on the negative side of the battery, and a precharge SMR connected in parallel to the positive SMR and having a resistor connected in series. Exists. A large-capacity electrolytic capacitor is provided between the terminals on the input side of the inverter so as to smooth the voltage fluctuation and stabilize the operation of the inverter. When driving the hybrid vehicle, the main SMR is closed by closing the ignition switch (the positive SMR and the negative SMR are closed), and the capacitor is charged. However, if the capacitor is directly charged by the battery, a large current flows and the SMR flows. May damage the contacts. Therefore, first, the precharge SMR is closed, the capacitor is precharged while limiting the current with a limiting resistor or the like, and the main SMR is closed after the precharge is completed, thereby preventing damage to the contact of the SMR.

  In the case of having such an electric circuit, when the electric circuit breaks down during precharging, when the electric circuit is short-circuited, a large current flows, and a fault such as a limiting resistor breaks down. There is.

  However, in Patent Document 1 described above, only a short circuit abnormality is detected. For this reason, even if it is the same disconnection failure, since the disconnection failure of an electric circuit and the disconnection failure (disconnection failure by a short circuit) resulting from the short circuit of an electric circuit are not distinguished, exact repair cannot be performed.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a power supply circuit that can accurately determine the cause of a disconnection failure occurring in a vehicle power supply circuit having a precharge function. An anomaly detection device is provided.

  An abnormality detection device according to a first aspect of the invention detects an abnormality of a power supply circuit including a power storage mechanism and a plurality of relays. The power supply circuit is connected in parallel to the first relay for controlling electrical energization / non-energization between the load and one pole of the power storage mechanism, and a circuit connected in series to the first relay. And a third relay that controls electrical energization / non-energization between the load and the other pole of the power storage mechanism. This abnormality detection device detects the current value of the power storage mechanism at the initial stage of the precharge process executed by energizing the first relay and the third relay before energizing the second relay and the third relay. Means for detecting the voltage value of the power storage mechanism and the voltage value of the load when the precharge processing time has elapsed, and the voltage value of the power storage mechanism when the precharge processing time has elapsed Based on the current value of the power storage mechanism at the initial stage of the precharge process when it is determined that there is a disconnection failure and a means for determining that the disconnection failure is caused when the voltage value of the load is not substantially equal Determining means for determining whether or not a short circuit has occurred.

  According to the first invention, when the precharge processing time elapses, if the power supply circuit is normal, the voltage value of the power storage mechanism and the voltage value of the load become substantially equal. However, the fact that these voltage values are not approximately equal indicates that the power supply circuit is disconnected and power is not supplied from the power storage mechanism to the load. As described above, when it is determined that there is a disconnection failure, the determination unit determines whether or not a short circuit has occurred in the power supply circuit based on the current value of the power storage mechanism at the initial stage of the precharge process. Assuming that no disconnection occurred at the start of the precharge process, a short circuit occurred in the subsequent precharge process, and a large current flowed into the resistor, etc., resulting in the breakdown of components such as the resistor, resulting in a disconnection failure. Conceivable. When the precharge processing time elapses, it is possible to detect only an event that the voltage value of the power storage mechanism and the voltage value of the load are not substantially equal, both of the disconnection failure and the disconnection failure due to a short circuit of the power supply circuit during precharging. At this time, if the current value of the power storage mechanism at the start of the precharge process is equal to or greater than the threshold value, it can be determined that the current has flowed without disconnection until that time. Since a disconnection failure occurred after that, in such a case, it can be determined that a short circuit occurred in the power supply circuit and the disconnection failure occurred. On the other hand, if the current value of the power storage mechanism at the start of the precharge process is not greater than or equal to the threshold value (very close to 0), then a disconnection has already occurred, so no current is flowing and a short circuit has occurred. It can be determined that there is no. As a result, it is possible to provide an abnormality detection device for a power supply circuit that can accurately determine the cause of a disconnection failure occurring in a vehicle power supply circuit having a precharge function.

  In the abnormality detection device according to the second invention, in addition to the configuration of the first invention, the determination means determines that a short circuit has occurred in the power supply circuit if the current value is equal to or greater than a predetermined threshold value. Means for doing so.

  According to the second aspect of the invention, if the current value of the power storage mechanism at the start of the precharge process is equal to or greater than the threshold value, it can be determined that no current has been broken and current has flowed until that time. Since a disconnection failure occurred after that, in such a case, it can be determined that a short circuit occurred in the power supply circuit and the disconnection failure occurred.

  In the abnormality detection device according to the third aspect of the invention, in addition to the configuration of the first aspect of the invention, the determination means determines that a short circuit has not occurred in the power supply circuit unless the current value is equal to or greater than a predetermined threshold value. Means for determining.

  According to the third invention, if the current value of the power storage mechanism at the start of the precharge process is not equal to or greater than a threshold value (very close to 0), then a disconnection has already occurred and no current flows. It can be determined that no short circuit has occurred in the power supply circuit.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  With reference to FIG. 1, a vehicle equipped with an abnormality detection apparatus according to an embodiment of the present invention will be described. This vehicle includes a battery 100, an inverter 200, a traveling motor 300, a capacitor 400, an SMR (1) 500, a limiting resistor 502, an SMR (2) 504, an SMR (3) 506, an ECU ( Electronic Control Unit) 600. The abnormality detection device according to the present embodiment is realized by a program executed by ECU 600. In the present embodiment, the vehicle is described as an electric vehicle that travels only by the driving force from the traveling motor 300. However, the vehicle on which the abnormality detection device for a power supply circuit according to the present invention is mounted is not limited to an electric vehicle. In addition, it may be mounted on a hybrid vehicle, a fuel cell vehicle or the like.

  The battery 100 is an assembled battery in which a plurality of modules in which a plurality of cells are connected in series are further connected in series. A capacitor may be used instead of the battery 100.

  Inverter 200 includes six IGBTs (Insulated Gate Bipolar Transistors) and six diodes connected in parallel to each IGBT so that a current flows from the emitter side to the collector side of the IGBT. The inverter 200 converts the current supplied from the battery 100 from a direct current to an alternating current by turning on / off (energizing / cutting off) the gate of each IGBT based on a control signal from the ECU 600. 300. Inverter 200 and IGBT may use a well-known technique, and therefore, detailed description thereof will not be repeated here.

  Traveling motor 300 is a three-phase AC motor. The rotation shaft of the traveling motor 300 is finally connected to a drive shaft (not shown) of the vehicle. The vehicle travels by the driving force from the travel motor 300.

  The capacitor 400 is connected in parallel with the inverter 200. Capacitor 400 temporarily stores electric charge in order to smooth the power supplied from battery 100 or the power supplied from inverter 200. The smoothed power is supplied to the inverter 200 or the battery 100.

  SMR (1) 500 and SMR (2) 504 are provided on the positive electrode side of battery 100. SMR (1) 500 and SMR (2) 504 are connected in parallel. A limiting resistor 502 is connected to the SMR (1) 500 in series. SMR (1) 500 is a precharge SMR that is connected before SMR (2) 504 is connected and prevents an inrush current from flowing through inverter 200. SMR (2) 504 is a positive SMR connected after SMR (1) 500 is connected and precharge is completed. SMR (3) 506 is a negative SMR provided on the negative electrode side of battery 100. Each SMR is controlled by ECU 600.

  The ECU 600 executes a program stored in a ROM (Read Only Memory) based on the amount of depression of an ignition switch (not shown), an accelerator pedal (not shown), the amount of depression of a brake pedal (not shown), etc. Then, the inverter 200 and each SMR are controlled to drive the vehicle in a desired state. The ECU 600 is connected to a voltmeter 602 that detects the voltage of the capacitor 400. ECU 600 detects voltage value VH of inverter 200 (traveling motor 300) by detecting the voltage of capacitor 400.

  Further, a voltmeter 604 that detects a voltage value VB of the battery 100 and an ammeter 606 that detects a current value IB of the battery 100 are connected to the ECU 600.

  SMR (1) 500, SMR (2) 504, and SMR (3) 506 are relays that close contacts when an exciting current is applied to a coil. The relationship between the operation state of SMR (1) 500, SMR (2) 504, and SMR (3) 506 and the position of the ignition switch will be described. The ignition switch has an OFF (off) position, an ACC position, an ON (on) position, and a STA (start) position. When the power is shut down, that is, when the position of the ignition switch is in the OFF position, SMR (1) 500, SMR (2) 504, and SMR (3) 506 are turned off. That is, the excitation current for the coils of each SMR (1) 500, SMR (2) 504, and SMR (3) 506 is turned off. The ignition switch position is switched in the order of OFF position → ACC position → ON position → STA position, and automatically returns from the STA position to the ON position. The application of the present invention is not limited to such a switch.

  When the power supply is connected, that is, when the ignition switch position is switched from the OFF position to the STA position via the ACC position and the ON position, ECU 600 first turns on SMR (3) 506 and then turns on SMR (1) 500. Then, precharge is executed. Since the limiting resistor 502 is connected to the SMR (1) 500, the voltage value VH of the inverter 200 rises gently even when the SMR (1) 500 is turned on, and the occurrence of an inrush current can be prevented.

  In addition, including the case where the position of the ignition switch does not have such four positions, the abnormality detection apparatus according to the present embodiment (implemented by a program executed in ECU 600) starts precharging. Then, abnormality detection is executed.

  ECU 600 precharges when voltage value VH of inverter 200 reaches, for example, about 80% of battery voltage value VB, or when voltage value VH of inverter 200 becomes substantially equal to battery voltage value VB. The charging is completed, SMR (1) 500 is turned off, and SMR (2) 504 is turned on. The time required for this precharge is set in advance. The set time is described as precharge time.

  On the other hand, when the position of the ignition switch is switched from the ON position to the OFF position, ECU 600 first turns off SMR (2) 504 and then turns off SMR (3) 506. As a result, the electrical connection between the battery 100 and the inverter 200 is cut off, and the power supply is cut off. At this time, the residual voltage on the drive circuit side is discharged, and the voltage value VH of the inverter 200 gradually converges to about 0 V (breaking voltage). In addition, the voltage value at the time of interruption | blocking does not necessarily need to be 0V, For example, the weak voltage value of about 2-3V may be sufficient.

  With reference to FIG. 2, a control structure of a program executed by ECU 600 to realize the abnormality detection device for the power supply circuit according to the present embodiment will be described.

  In step (hereinafter, step is abbreviated as S) 100, ECU 600 determines whether or not the ignition switch is at the start position by the driver. If the ignition switch is moved from the off position to the start position via the ACC position and the on position (YES in S100), the process proceeds to S110. If not (NO in S100), the process returns to S100 and waits until the ignition switch is set to the start position. That is, the abnormality determination process described below is performed when the ignition switch is moved to the start position and precharging is started. As described above, the present invention is not limited to the ignition switch. For this reason, the timing for starting the abnormality detection process is not particularly limited to the timing at which the ignition switch is at the start position as long as the precharge process is started.

  In S110, ECU 600 maintains SMR (2) 504 in the off state, and shifts SMR (1) 500 and SMR (3) 506 from the off state to the on state. Thereby, precharge is started.

  In S120, ECU 600 detects current value IB of battery 100. At this time, the current value IB of the battery 100 is detected based on a signal input from the ammeter 606 to the ECU 600. In S130, ECU 600 stores current value IB of battery 100 detected immediately after the start of precharging as IB (ini).

  In S140, ECU 600 determines whether or not the precharge time has elapsed. If the precharge time has elapsed (YES in S140), the process proceeds to S150. If not (NO in S140), the process returns to S140 and waits until the precharge time has elapsed.

  In S150, ECU 600 detects voltage value VH of inverter 200 and voltage value VB of battery 100. At this time, voltage value VH of inverter 200 is detected based on a signal input from voltmeter 602 to ECU 600, and voltage value VB of battery 100 is detected based on a signal input from voltmeter 604 to ECU 600.

  In S160, ECU 600 compares voltage value VH of inverter 200 with battery voltage value VB to determine whether or not they are substantially the same. If voltage value VH of inverter 200 and battery voltage value VB are compared and approximately the same (YES in S160), the process proceeds to S180. That is, power is normally supplied from the battery 100 to the inverter 200. If not (NO in S160), the process proceeds to S170.

  In S170, ECU 600 determines whether or not current value IB (ini) of battery 100 immediately after the start of the precharge stored in S130 is equal to or greater than an IB threshold value. If current value IB (ini) of battery 100 is equal to or greater than the IB threshold value (YES in S170), the process proceeds to S190. If not (NO in S170), the process proceeds to S200. Note that the IB threshold value is set so that the detection result and the noise can be separated based on the detection accuracy and resolution of the current sensor 606.

  In S180, ECU 600 determines that the power supply circuit is normal. In S190, ECU 600 determines that the power supply circuit has a disconnection failure due to a short-circuit current. In S200, ECU 600 determines that the power supply circuit has a disconnection failure.

  The operation of ECU 600 that is the abnormality detection device for the power supply circuit according to the present embodiment based on the above-described structure and flowchart will be described with reference to FIG. 3A shows a time change of the current value IB of the battery 100, and FIG. 3B shows a time change of the voltage value VH of the inverter 200, respectively. In FIG. 3A, when the solid line is normal, the dotted line indicates a disconnection failure, and the alternate long and short dash line indicates a disconnection failure due to a short-circuit current. In FIG. 3B, the solid line indicates normal, the dotted line indicates a disconnection failure, and a disconnection failure due to a short-circuit current, respectively. That is, as shown in FIG. 3B, the disconnection failure and the disconnection failure due to the short-circuit current cannot be distinguished only by the time change of the voltage value VH of the inverter 200.

  When the vehicle driver changes the ignition switch from the OFF position to the start position via the ACC position and the ON position (YES in S100), precharging is started (S110). That is, SMR (1) 500 and SMR (3) 506 are turned on, and SMR (2) 504 is turned off and precharged. This precharge is started at time t (0) shown in FIGS. 3 (A) and 3 (B).

  The current value IB of the battery 100 detected immediately after the start of the precharge is stored as IB (ini) (S130). At this time, IB (ini) is stored by time t (1) shown in FIG.

  When precharge time has elapsed (YES in S140), voltage value VH of inverter 200 and voltage value VB of battery 100 are detected (S150), and voltage value VH of inverter 200 and battery voltage value VB are substantially the same. Is determined (S160). This precharge time has elapsed at time t (2) shown in FIGS. 3 (A) and 3 (B).

  If voltage value VH of inverter 200 and battery voltage value VB are substantially the same when precharge time has elapsed (YES in S160), it is determined that this power supply circuit is normal (S180).

  When precharge time has elapsed, voltage value VH of inverter 200 and battery voltage value VB are not substantially the same (NO in S160), and current value IB (ini) of battery 100 immediately after the start of precharge is obtained. If it is equal to or greater than the IB threshold (YES in S170), it is determined that this power supply circuit is a disconnection failure due to a short-circuit current (S190).

  When precharge time has elapsed, voltage value VH of inverter 200 and battery voltage value VB are not substantially the same (NO in S160), and current value IB (ini) of battery 100 immediately after the start of precharge is obtained. If it is not equal to or greater than the IB threshold value (NO in S170), it is determined that this power supply circuit is a disconnection failure (S190).

  That is, immediately after the precharge is started, the current value IB (ini) of the battery 100 is equal to or greater than the IB threshold. This is because the precharge power is supplied from the battery 100 to the inverter 200 immediately after the precharge is started. Indicates that it was being supplied. However, since the voltage value VH of the inverter 200 has not substantially increased to the battery voltage value VB when the precharge time has elapsed, a short circuit occurs in a part of the electric circuit during the precharge, for example, a limitation. It is conceivable that the resistor 502 is electrically broken and disconnected at that portion. Therefore, in such a case (the voltage value VH of the inverter 200 and the battery voltage value VB are not substantially the same when the precharge time has elapsed, the current value IB (ini) of the battery 100 immediately after the start of precharge is the IB threshold. If it is greater than or equal to the value), it is determined that a disconnection failure has occurred due to the occurrence of a short-circuit current (S190).

  On the other hand, the fact that the current value IB (ini) of the battery 100 is not equal to or greater than the IB threshold immediately after the precharge is started means that the precharge power is supplied from the battery 100 to the inverter 200 even immediately after the precharge is started. Indicates that it was not. Therefore, when the precharge time has elapsed, the voltage value VH of the inverter 200 has not substantially increased to the battery voltage value VB. Therefore, in such a case (the voltage value VH of the inverter 200 and the battery voltage value VB are not substantially the same when the precharge time has elapsed, the current value IB (ini) of the battery 100 immediately after the start of precharge is the IB threshold. If it is not equal to or greater than the value, it is determined that a disconnection failure has occurred (S190).

  This will be described with reference to FIG. 3A. In the case of a disconnection failure due to a short-circuit current, as indicated by a one-dot chain line in FIG. 3A, at least at time t (1) from time t (0). Electric power is supplied from the battery 100 to the inverter 200 via the limiting resistor 502. A disconnection failure due to a short circuit occurred during the subsequent precharge, and the voltage value VH of the inverter 200 did not substantially increase to the voltage value VB of the battery 100 even when the precharge time elapsed. More specifically, shortly after the time t (1) in FIG. 3A, an electrical breakdown of the limiting resistor 502 or the like occurs due to a short circuit, resulting in a disconnection failure, and the current value IB of the battery 100 Suddenly drops to almost zero.

  On the other hand, in the case of disconnection before the precharge, the current value IB of the battery 100 is almost 0 immediately after the precharge, as indicated by the dotted line in FIG.

  As described above, in the ECU that is the abnormality detection device for the power supply circuit according to the present embodiment, the current value of the battery immediately after the precharge is stored, and when the precharge time has elapsed, the inverter voltage A disconnection failure in the case where the value has not substantially increased to the battery voltage value is distinguished and determined. If the current value of the battery immediately after precharging is greater than or equal to the IB threshold, it is a disconnection failure due to a short circuit during precharging, otherwise it is a disconnection failure not due to a short circuit during precharging (precharge). Disconnection from the front) and can be distinguished and determined.

  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.

1 is a diagram showing an overall configuration of a vehicle equipped with a power circuit abnormality detection device according to an embodiment of the present invention. It is a flowchart which shows the control structure of the abnormality determination program performed with ECU of FIG. It is a flowchart which shows a timing chart when the abnormality determination program is performed by ECU of FIG.

Explanation of symbols

  100 battery, 200 inverter, 300 travel motor, 400 capacitor, 500, 504, 506 SMR, 502 limiting resistance, 600 ECU, 602, 604 voltmeter, 606 ammeter.

Claims (3)

An abnormality detection device for a power circuit including a power storage mechanism and a plurality of relays, wherein the power circuit includes a first relay that controls electrical energization / non-energization between a load and one pole of the power storage mechanism, and Controls electrical energization / non-energization of a circuit having a resistor connected in series to the first relay, a second relay connected in parallel to the circuit, and the load and the other pole of the power storage mechanism A third relay,
The abnormality detection device is:
Before energizing the second relay and the third relay, the current value of the power storage mechanism at the initial stage of the precharge process executed by energizing the first relay and the third relay is detected. Means for
Means for detecting a voltage value of the power storage mechanism and a voltage value of the load when the precharge processing time has elapsed;
Means for determining a disconnection failure if the voltage value of the power storage mechanism and the voltage value of the load when the precharge processing time has elapsed are not substantially equal;
A power supply comprising: a determination unit configured to determine whether or not a short circuit has occurred in the power supply circuit based on a current value of the power storage mechanism at an initial stage of the precharge process when the disconnection failure is determined. Circuit abnormality detection device.   The power supply circuit abnormality detection device according to claim 1, wherein the determination means includes means for determining that a short circuit has occurred in the power supply circuit when the current value is equal to or greater than a predetermined threshold value. .   The power supply circuit abnormality detection according to claim 1, wherein the determination means includes means for determining that a short circuit has not occurred in the power supply circuit if the current value is not equal to or greater than a predetermined threshold value. apparatus.

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