JP2013027094A - Abnormality determination device of electric system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To specify a portion at which abnormality occurs.SOLUTION: When a system voltage VH detected by a voltage sensor 180 is lower than a target voltage defined from a voltage VL detected by a voltage sensor 262, it is determined as abnormality. When abnormality occurs, a converter 200 and one of a voltage sensor 180 and a voltage sensor 262 are specified as a portion at which the abnormality occurs, according to whether or not a current IL flowing through a reactor 202 during a switching operation of the converter 200 increases or decreases. when the current IL flowing through the reactor 202 during the switching operation of the converter 200 increases or decreases, the voltage sensor 180 and the voltage sensor 262 are specified as a portion at which the abnormality occurs. When the current IL flowing through the reactor 202 during the switching operation of the converter 200 does not increase or decrease, the converter 200 is specified as a portion at which the abnormality occurs.

Description

  The present invention relates to an abnormality determination device for an electrical system, and more particularly to a technique for identifying a site where an abnormality has occurred in an electrical system.

  A hybrid vehicle, an electric vehicle, a fuel cell vehicle and the like equipped with an electric motor as a driving source are known. Such vehicles include a power supply device (battery, capacitor, etc.) that supplies electric power to an electric motor, a converter for boosting or stepping down a voltage, and an electric device such as an inverter for converting direct current to alternating current. And an electrical system provided.

  For example, if an abnormality occurs in the converter in the electric system and the voltage cannot be increased to a desired voltage, the electric motor cannot be driven to obtain the driving force desired by the driver. Therefore, as described in JP 2007-68305 A (Patent Document 1), it is necessary to determine whether an abnormality has occurred in the converter. In Japanese Patent Application Laid-Open No. 2007-68305, as described in claim 5 and the like, the absolute value of the deviation between the voltage value on the input side and the voltage value on the output side of the converter is smaller than the threshold value, and the output If the voltage value on the side is smaller than the threshold value, it is determined that an abnormality has occurred in the converter.

JP 2007-68305 A

  However, when an abnormality occurs in the voltage sensor, it can be erroneously determined that an abnormality has occurred in the converter even if the converter is normal.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to identify a site where an abnormality has occurred by distinguishing between a converter and a voltage sensor.

  In an embodiment, an abnormality determination device for an electrical system provided with a converter and a voltage sensor for detecting a voltage of a circuit connected to the converter generates an abnormality according to the voltage detected by the voltage sensor. A determination means for determining whether or not an abnormality has occurred, and in the event of an abnormality, either the converter or the voltage sensor is switched depending on whether the current flowing through the converter increases or decreases during the switching operation of the converter. And a specifying means for specifying the site where the abnormality has occurred.

  According to this configuration, when it is detected that an abnormality has occurred from the voltage detected by the voltage sensor, the current flowing through the converter during the switching operation of the converter depending on whether the converter is normal or abnormal. Based on the difference in the behaviors, it is specified which of the converter and the voltage sensor is abnormal.

  In another embodiment, when an alternating current in the converter is detected, the voltage sensor is identified as the site where the abnormality has occurred.

  According to this configuration, if the converter is normal, the current flowing through the converter increases or decreases during the switching operation of the converter. Therefore, if the current flowing through the converter increases or decreases during the switching operation of the converter, the voltage sensor, not the converter, malfunctions. Identified as the site where it occurred.

  In yet another embodiment, if the current flowing through the converter does not increase or decrease during the switching operation of the converter, the converter is identified as a site where an abnormality has occurred.

  According to this configuration, if an abnormality occurs in the converter, the current flowing through the converter does not increase or decrease during the switching operation of the converter. Therefore, if the current flowing through the converter does not increase or decrease during the switching operation of the converter, , Identified as the site where the abnormality occurred.

  In yet another embodiment, the voltage sensor includes a first voltage sensor and a second voltage sensor. The first voltage sensor detects a voltage of a circuit connected to the input side of the converter. The second voltage sensor detects a voltage of a circuit connected to the output side of the converter. If the voltage detected by the second voltage sensor is lower than the target voltage determined from the voltage detected by the first voltage sensor, it is determined that an abnormality has occurred.

  According to this configuration, an abnormality can be detected because the amount of increase in voltage is insufficient.

1 is a schematic configuration diagram of a vehicle. It is a figure which shows the electric system of a vehicle. It is a flowchart which shows the process which ECU performs.

  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.

  Referring to FIG. 1, the vehicle includes a motor generator 110, a speed reducer 140, and a battery 150. In the present embodiment, an electric vehicle equipped with only motor generator 110 as a drive source will be described as an example. However, a hybrid vehicle equipped with an engine or a fuel cell vehicle equipped with a fuel cell may be used.

  Motor generator 110 is a three-phase AC rotating electric machine including a U-phase coil, a V-phase coil, and a W-phase coil. Motor generator 110 is driven by electric power stored in battery 150. Torque generated by the motor generator 110 is transmitted to the front wheels 160 via the speed reducer 140. The rear wheels may be driven instead of or in addition to the front wheels 160.

  During regenerative braking of the vehicle, the motor generator 110 is driven by the front wheels 160 via the speed reducer 140, and the motor generator 110 operates as a generator. Thus, motor generator 110 operates as a regenerative brake that converts braking energy into electric power. The electric power generated by motor generator 110 is stored in battery 150. Motor generator 110 is controlled by an ECU (Electronic Control Unit) 170. ECU 170 may be divided into a plurality of ECUs.

The battery 150 is an assembled battery configured by connecting a plurality of battery modules in which a plurality of battery cells are integrated in series.

  As shown in FIG. 2, voltage VB of battery 150 is detected by voltage sensor 152, and current IB of battery 150 is detected by current sensor 154. A signal representing voltage VB and a signal representing current IB are input to ECU 170.

  FIG. 2 shows a vehicle electrical system. The electrical system includes a converter 200, an inverter 210, a DC / DC converter 230, an auxiliary battery 240, a positive side system main relay 251, a negative side system main relay 252, a precharge system main relay 253, A resistor 254.

  Converter 200 includes a reactor 202, two npn transistors, and two diodes. Reactor 202 has one end connected to the positive electrode side of battery 150 and the other end connected to a connection point between two npn transistors. Current IL flowing through reactor 202, that is, current flowing through converter 200, is detected by current sensor 204 and input to ECU 170. Since ECU 170 operates at a predetermined cycle, current IL flowing through reactor 202 is repeatedly detected at the same or substantially the same cycle as the operation cycle of ECU 170.

  Two npn-type transistors are connected in series. The npn transistor is controlled by the ECU 170. A diode is connected between the collector and emitter of each npn transistor so that a current flows from the emitter side to the collector side.

As an npn transistor, for example, an IGBT (Insulated Gate Bipolar)
Transistor) can be used. Instead of the npn type transistor, a power switching element such as a power MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) can be used.

  When the electric power discharged from battery 150 is supplied to motor generator 110, the voltage is boosted by the switching operation of converter 200. As is well known, by repeating the boosting operation of turning on the lower arm transistor to accumulate electricity in the reactor 202 and turning on the upper arm transistor to discharge electricity at a predetermined cycle (duty ratio), the voltage is reduced. Boosted. Conversely, when the battery 150 is charged with the electric power generated by the motor generator 110, the voltage is stepped down by the converter 200.

  System voltage VH between converter 200 and inverter 210 is detected by voltage sensor 180. The detection result of voltage sensor 180 is transmitted to ECU 170. Voltage sensor 180 is a voltage sensor for detecting the voltage of the circuit connected to the output side when converter 200 performs a boost operation.

  Inverter 210 includes a U-phase arm, a V-phase arm, and a W-phase arm. The U-phase arm, V-phase arm and W-phase arm are connected in parallel. Each of the U-phase arm, the V-phase arm, and the W-phase arm has two npn transistors connected in series. Between the collector and emitter of each npn-type transistor, a diode for passing a current from the emitter side to the collector side is connected. A connection point of each npn transistor in each arm is connected to an end portion different from neutral point 112 of each coil of motor generator 110.

Inverter 210 converts a direct current supplied from battery 150 into an alternating current and supplies the alternating current to motor generator 110. The inverter 210 is connected to the motor generator 1.
The alternating current generated by 10 is converted into a direct current.

  DC / DC converter 230 is connected in parallel with converter 200 between battery 150 and converter 200. The DC / DC converter 230 steps down the direct current voltage. The electric power output from the DC / DC converter 230 is charged in the auxiliary battery 240. The electric power charged in the auxiliary battery 240 is supplied to an auxiliary machine 242 such as an electric oil pump and an electric compressor of an air conditioner, and the ECU 170.

  The positive side system main relay 251, the negative side system main relay 252, the precharging system main relay 253, and the resistor 254 are provided between the battery 150 and the DC / DC converter 230 as an example.

  Positive side system main relay 251 is connected to the positive side of battery 150. The negative side system main relay 252 is connected to the negative side of the battery 150. The precharge system main relay 253 is connected in parallel to the negative side system main relay 252 and in series to the resistor 254. That is, a circuit in which the precharge system main relay 253 and the resistor 254 are connected in series is connected in parallel to the negative side system main relay 252.

  For example, the positive switch system main relay 251, the negative switch system main relay 252, and the precharge system main relay 253 are all off (open), and the driver turns on the start switch (may be an ignition switch). When the electric system is activated by operating, first, the positive system main relay 251 and the precharge system main relay 253 are turned on (closed). Thereby, the smoothing capacitor 260 is precharged. During precharge, the operations of converter 200 and inverter 210 are stopped.

  After the smoothing capacitor 260 is precharged, the negative side system main relay 252 is turned on. Thereafter, the precharge system main relay 253 is turned off.

  The voltage VL of the smoothing capacitor 260 is detected by the voltage sensor 262. The detection result of the voltage sensor 262 is transmitted to the ECU 170. Voltage sensor 262 is a voltage sensor for detecting the voltage of a circuit connected to the input side when converter 200 performs a boost operation.

  The voltage VL of the smoothing capacitor 260 calculates the target value of the target output voltage when the converter 200 performs a boost operation, that is, the system voltage VH (the voltage of the circuit connected to the output side when the converter 200 performs the boost operation). Used for.

  For example, the target value of system voltage VH is calculated by multiplying voltage VL of smoothing capacitor 260 by a boost ratio determined from the duty ratio of the switching operation of converter 200. The method for calculating the target value of the system voltage VH is not limited to this.

  In the present embodiment, if the system voltage VH detected by the voltage sensor 180 is lower than the target value of the system voltage VH (target voltage determined from the voltage VL of the smoothing capacitor 260 detected by the voltage sensor 262), ECU 170 determines that an abnormality has occurred.

Furthermore, in the present embodiment, when an abnormality occurs, converter 200 and voltage depend on whether current IL flowing through reactor 202 (current flowing through converter 200) increases or decreases during the switching operation of converter 200. One of the sensor 180 and the voltage sensor 262 is specified by the ECU 170 as a part where an abnormality has occurred.

  If converter 200 is normal, current IL flowing through reactor 202 increases and decreases during the switching operation of converter 200. Therefore, when current IL flowing through reactor 202 increases and decreases during the switching operation of converter 200, voltage sensor instead of converter 200 is used. 180 and the voltage sensor 262 are specified as a site where an abnormality has occurred. In the present embodiment, it is not specified which of the voltage sensor 180 and the voltage sensor 262 is abnormal.

  On the other hand, if abnormality occurs in converter 200, current IL flowing through reactor 202 does not increase or decrease during switching operation of converter 200. Therefore, voltage sensor does not increase or decrease current IL flowing through reactor 202 during switching operation of converter 200. 180 and not the voltage sensor 262 but the converter 200 are specified as the part where the abnormality has occurred.

  As an example, when the time-series data of the current IL flowing through the reactor 202 is frequency-converted and the gain in the frequency range corresponding to the switching frequency of the converter 200 is abnormal to a predetermined value, the current flowing through the reactor 202 during the switching operation of the converter 200 It is determined that IL has increased or decreased.

  As another example, if the difference between the maximum value and the minimum value of the time series data of the current IL flowing through the reactor 202 is greater than or equal to a predetermined value, it is determined that the current IL flowing through the reactor 202 has increased or decreased during the switching operation of the converter 200. Is done.

  As yet another example, the amount of change in the current IL flowing through the reactor 202 from the previous detection value (the absolute value of the difference between the previous detection value and the current detection value) becomes a predetermined value or more within a predetermined period. If the ratio is greater than or equal to the threshold value, it is determined that current IL flowing through reactor 202 has increased or decreased during the switching operation of converter 200.

  Note that the method for determining that the current IL flowing through the reactor 202 has increased or decreased during the switching operation of the converter 200 is not limited thereto. In short, when the frequency component of the switching operation is included in the frequency of the current IL flowing through the reactor 202 during the switching operation of the converter 200, the voltage sensor 180 and the voltage sensor 262 are specified as the portion where the abnormality has occurred. If the frequency of the current IL flowing through the reactor 202 during the switching operation of the converter 200 does not include the frequency component of the switching operation, the converter 200 is specified as a portion where an abnormality has occurred.

  Processing executed by ECU 170 will be described with reference to FIG. The processing described below may be realized by software, may be realized by hardware, or may be realized by cooperation of software and hardware.

  In step (hereinafter, step is abbreviated as S) 100, the switching operation of converter 200, more specifically, the boosting operation is started. Thereafter, in S102, it is determined whether or not there is an abnormality in the boosting operation.

  As described above, if the system voltage VH detected by the voltage sensor 180 is lower than the target value of the system voltage VH determined from the voltage VL of the smoothing capacitor 260 detected by the voltage sensor 262, it is determined that an abnormality has occurred. (YES in S102).

  If it is determined that an abnormality has occurred (YES in S102), it is determined in S104 whether current IL flowing through reactor 202 (current flowing through converter 200) increases or decreases during the switching operation of converter 200.

  If current IL flowing through reactor 202 increases or decreases during the switching operation of converter 200 (YES in S104), voltage sensor 180 and voltage sensor 262 are identified as sites where abnormality has occurred in S106.

  If current IL flowing through reactor 202 does not increase or decrease during switching operation of converter 200 (NO in S104), converter 200 is identified as a site where an abnormality has occurred in S108. More specifically, the transistor on the upper arm of converter 200 is specified as a site where an abnormality has occurred.

  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.

  110 motor generator, 140 speed reducer, 150 battery, 152 voltage sensor, 154 current sensor, 160 front wheel, 170 ECU, 180, 262 voltage sensor, 200 converter, 202 reactor, 204 current sensor, 210 inverter, 230 DC / DC converter, 240 Auxiliary battery, 242 Auxiliary machine, 251 Positive side system main relay, 252 Negative side system main relay, 253 System main relay for precharging, 254 Resistance, 260 Smoothing capacitor.

Claims (4)

An electrical system abnormality determination device provided with a converter and a voltage sensor for detecting a voltage of a circuit connected to the converter,
Determining means for determining whether an abnormality has occurred according to the voltage detected by the voltage sensor;
When an abnormality occurs, one of the converter and the voltage sensor is identified as the part where the abnormality has occurred, depending on whether the current flowing through the converter increases or decreases during the switching operation of the converter. An abnormality determination device for an electrical system, comprising a specifying means for   The electrical system abnormality determination device according to claim 1, wherein when the current flowing through the converter increases or decreases during the switching operation of the converter, the specifying unit specifies the voltage sensor as a site where an abnormality has occurred.   2. The abnormality determination device for an electric system according to claim 1, wherein if the current flowing through the converter does not increase or decrease during the switching operation of the converter, the specifying unit specifies the converter as a portion where an abnormality has occurred. The voltage sensor includes a first voltage sensor and a second voltage sensor,
The first voltage sensor detects a voltage of a circuit connected to the input side of the converter,
The second voltage sensor detects a voltage of a circuit connected to the output side of the converter,
The determination unit determines that an abnormality has occurred when a voltage detected by the second voltage sensor is lower than a target voltage determined from a voltage detected by the first voltage sensor. 4. The abnormality determination device for an electrical system according to any one of 3 above.

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