JP2007242247A - Arrangement for controlling vehicular power supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance reliability by surely preventing troubles and failures caused by a rush current of a main relay even if a capacitive component on the load side changes and pre-charge resistance changes. <P>SOLUTION: After charge is started while restricting a rush current to a capacitor by switching on a pre-charge relay (S1), the output voltage V1 of a battery and the charge voltage V2 of a capacitor are monitored by reading a signal from a voltage sensor (S2). Then, whether the voltage difference between the output voltage V1 of the battery and the charge voltage V2 of the capacitor (V1-V2) is not more than a threshold value Vs or not is checked (S3), a main relay is switched on at the point of time when Vs≥(V1-V2) is satisfied to directly connect the battery to the capacitor (and a load) (S4), and the pre-charge relay is switched off (S5). Thereby, troubles and failures caused by the rush current of the main relay are surely prevented even if the capacitive component on the load side changes and the pre-charge resistance changes. and reliability can be enhanced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for a vehicle power supply system having a main relay for intermittently connecting a vehicle main power supply and a load, and a precharge relay connected in parallel to the main relay.

  Conventionally, in a vehicle such as an electric vehicle, a main power source such as a battery and a load side such as an inverter are separated by a power relay for safety. The relay contact may be welded by the inrush current to the load. Accordingly, in general, the power relay includes a main relay interposed between the battery and the load, and a relay (so-called precharge relay) connected in parallel to the main relay via a resistor. A technique of connecting a main power supply relay after charging a load-side capacity via a relay is generally employed.

For example, in Patent Document 1, a precharge circuit is connected in parallel to a main relay including a main coil and a subcoil, and a precharge resistor of the precharge circuit is connected in parallel to a subcoil of the main relay. Thus, there is disclosed a technique for reliably switching on the main relay and saving power consumption when the main relay is kept on.
JP 2003-323838 A

  However, conventionally, when charging a load-side capacity by a precharge relay, a charge time (precharge time) is set in advance from the voltage and the capacitor capacity, and the precharge relay is set only for the preset precharge time. To connect the battery and the load.

  For this reason, charging may not be completed due to changes in capacitor capacity, variation in precharge resistance, etc., and when the main relay is connected after the precharge time has passed, the current flowing through the relay contact cannot be reduced sufficiently. There is a risk of problems such as contact welding. Furthermore, it is difficult to cope with the case where the capacitance of the capacitor decreases due to aging deterioration or the resistance value increases abnormally due to heat loss of the precharge resistor.

  The present invention has been made in view of the above circumstances, and can reliably prevent problems caused by the inrush current of the main relay even when the load side capacity changes or the precharge resistance changes, improving reliability. It is an object of the present invention to provide a control device for a vehicle power supply system that can be used.

  In order to achieve the above object, a control device for a vehicle power supply system according to the present invention includes a main relay for intermittently connecting a vehicle main power supply and a load, and a precharge connected in parallel to the main relay via a precharge resistor. A control device for a vehicle power supply system having a relay, a voltage difference between the voltage on the main power supply side and the voltage on the load side is obtained, and a comparison means for comparing the voltage difference with a preset threshold value; When the voltage difference exceeds the threshold value as a result of comparison by the comparison means, the relay contact of the precharge relay is closed with the relay contact of the main relay opened, and the main power supply side and the load When the voltage difference falls below the threshold value, the relay contact of the precharge relay is opened and the main relay is connected. To close the relay contacts, characterized in that a relay control means for connecting the main power source side and the load side.

  The control device for a vehicle power supply system according to the present invention can reliably prevent a failure due to the inrush current of the main relay even when the load-side capacity is changed or the precharge resistance is changed, thereby improving reliability. be able to.

  Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 relate to a first embodiment of the present invention, FIG. 1 is a circuit configuration diagram of a power supply system, FIG. 2 is a functional configuration diagram of a control device, FIG. 3 is a flowchart of a relay control sequence, and FIG. FIG. 5 is a circuit configuration diagram showing another modification of the power supply system.

  The power supply system shown in FIG. 1 is a system that uses a battery 1 mounted on an electric vehicle or the like and supplies high-voltage DC power as a main power source. The main relay 10 connects and disconnects the battery 1 and a load 50, and the main relay. The relay controller 30 that controls the precharge relay 20, the main relay 10, and the precharge relay 20 that are connected in parallel with the main controller 10 is a main component. A capacitor 40 is connected in parallel to the front stage of the load 50 for supplying the load 50 with a smoothed voltage obtained by removing ripples included in the output from the battery 1.

  In FIG. 1, as the load 50 of the battery 1, an inverter 51 that converts electric power from the battery 1 from direct current to alternating current, and a three-phase motor 52 that is driven by the alternating current power from the inverter 51 are illustrated. The load of the battery 1 includes a DC motor, a DC-DC converter, and the like. Depending on the system configuration, the capacitor 40 may not be provided separately from the load. In that case, the capacitor 40 represents the capacity of the load.

  The main relay 10 includes a relay contact 10a that connects and disconnects the battery 1, the capacitor 40, and the load 50, and an electromagnetic coil 10b that drives the relay contact 10a to open and close. The energization of the electromagnetic coil 10b is controlled by the relay control device 30. The The precharge relay 20 is a relay for precharging (precharging) the capacitor 40 before turning on the main relay 10, and a battery is connected between the relay contact 20 a of the precharge relay 20 and the capacitor 40. A precharge resistor 21 for limiting the inrush current from 1 is connected. The electromagnetic coil 20 b that opens and closes the relay contact 20 a of the precharge relay 20 is controlled by the relay control device 30.

  On the other hand, the relay control device 30 is composed mainly of a microcomputer. As shown in FIG. 2, a ROM 32 storing work programs and control programs and various fixed data for control are stored in a bus line of a CPU 31 serving as a central processing unit. A RAM 33 to be stored, an A / D converter 34 for converting analog data into digital data, an I / O interface 35 for inputting / outputting various signals, and a communication module 36 for data communication with other devices are connected. .

  Signals from the voltage sensors 60 and 61 are input to the relay control device 30 via the A / D converter 34. The voltage sensors 60 and 61 are sensors for detecting the output voltage V1 of the battery 1 and the charging voltage V2 of the capacitor 40, respectively. As shown in FIG. 1, the output line of the battery 1 and the input of the inverter 51, respectively. It is arranged in the line. The voltage sensors 60 and 61 may be embedded in the battery 1 and the inverter 51, respectively.

  The relay control device 30 compares the output voltage V1 of the battery 1 and the charging voltage V2 of the capacitor 40 with the function as the comparison means and the function as the relay control means, and determines the opening / closing timing of the main relay 10 and the precharge relay 20. Then, the energization of the electromagnetic coils 10b and 20b of the relays 10 and 20 is turned on and off. Specifically, the determination of the relay opening / closing timing and the energization control are executed according to a relay control sequence stored in advance as a control program in the ROM 32 of the relay control device 30. Next, the relay control sequence will be described with reference to the flowchart of FIG.

  In this relay control sequence, first, the precharge relay 20 is turned on in the first step S1 to energize the electromagnetic coil 20b. By energizing the electromagnetic coil 20 b of the precharge relay 20, the relay contact 20 a is closed and the battery 1 and the capacitor 40 are connected via the precharge resistor 21, and the battery 1 to the capacitor 40 is connected by the precharge resistor 21. The charging is started while limiting the inrush current.

  Next, in step S2, signals from the voltage sensors 60 and 61 are read, and the output voltage V1 of the battery 1 and the charging voltage V2 of the capacitor 40 are monitored. In step S3, it is checked whether or not the voltage difference (V1−V2) between the output voltage V1 of the battery 1 and the charging voltage V2 of the capacitor 40 is equal to or less than the threshold value Vs. The threshold value Vs is an allowable voltage difference in which the current flowing through the relay contact 10a does not cause contact welding when the relay contact 10a of the main relay 10 is closed and the battery 1 and the capacitor 40 (and the load 50) are directly connected. This is a value to be set, obtained in advance by simulation or experiment, and stored in advance in the ROM 32 of the relay control device 30 as fixed data.

  As a result, when Vs <(V1−V2), the process returns from step S3 to step S2 to continue monitoring the voltages V1 and V2, and when Vs ≧ (V1−V2) is satisfied, the process proceeds from step S3 to step S3. Proceeding to S4, the main relay 10 is turned on to energize the electromagnetic coil 10b. By energizing the electromagnetic coil 10b of the main relay 10, the relay contact 10a is closed, the precharge resistor 21 is short-circuited, and the battery 1 and the capacitor 40 (and the load 50) are directly connected. In step S5, the precharge relay 20 is turned off, and this sequence is completed.

  For simplicity, it is also possible to control the main relay 10 and the precharge relay 20 by monitoring only the charging voltage V2 of the capacitor 40. In this case, the voltage V1 of the battery 1 is Treated as a preset voltage value for each driving situation such as driving.

  Here, the relay control device 30 that executes the above-described relay control sequence is not limited to the configuration illustrated in FIG. 1, and may have various configurations. For example, a signal from the voltage sensor 60 that detects the battery voltage and a signal from the voltage sensor 61 that detects the capacitor voltage are processed by separate devices connected to each other via a communication line, and the main relay 10 is processed by one device. The precharge relay 20 may be controlled.

  In addition, as shown in FIG. 4, the battery control device 100 having a relay control function and the inverter control device 200 that controls the inverter 51 are connected to each other via a communication line 150 to form the relay control device 30. Anyway. The battery control device 100 is configured around a microcomputer 100a that is integrally installed in the casing or the like of the battery 1, and similarly, the inverter control device 200 is also integrally installed in the casing or the like of the inverter 51. 200a is the center. The voltage sensor 60 for detecting the battery voltage and the voltage sensor 61 for detecting the capacitor voltage are embedded in the battery 1 and the inverter 51, respectively, and the voltage value detected by the voltage sensor 61 is transmitted from the inverter control device 200 to the battery control device 100. As a result, the battery control device 100 controls the main relay 10 and the precharge relay 20.

  Further, the relay control device 30 can realize the above-described relay control sequence function by a hardware circuit without incorporating a microcomputer. FIG. 5 shows a relay control device 30A provided with a hardware circuit mainly including a differential amplifier 37 and a comparator 38, and this hardware circuit realizes a function equivalent to the above-described relay control sequence.

  That is, the signals of the voltage sensors 60 and 61 are input to the differential amplifier 37, and a voltage ΔV corresponding to the voltage difference (V 1 −V 2) is output from the differential amplifier 37. The output voltage ΔV of the differential amplifier 37 is input to the comparator 38 and compared with a reference voltage Vref corresponding to the threshold value Vs. The main relay 10 and the precharge relay 20 are turned on and off in an inverse relationship with each other by the output of the comparator 38 according to the comparison result between the voltage ΔV and the reference voltage Vref and the output obtained by inverting the output. The

  As described above, in this embodiment, even if the capacitance of the capacitor 40 or the resistance value of the precharge resistor 21 varies, or the capacitance of the capacitor or the resistance value changes due to secular change, the capacitor is surely obtained. 40 can be charged to make the voltage difference between the battery voltage and the capacitor charging voltage below an allowable value, and an excessive inrush current can be prevented from flowing through the relay contact 10a of the main relay 10 to ensure contact welding. It can be avoided and the reliability can be improved.

  Next, a second embodiment of the present invention will be described. FIG. 6 is a flowchart of the relay control and diagnosis sequence according to the second embodiment of the present invention.

  The second form adds a diagnostic function for diagnosing abnormality of the capacitor 40 and the precharge resistor 21 in addition to the relay control function. That is, the capacity of the capacitor 40 decreases due to aging or deterioration due to heat generation, and in an extreme case, an abnormality such as a capacity loss occurs. In addition, the precharge resistor 21 also has a resistance value that increases due to heat generation due to deterioration or loss due to secular change, and there is a risk of disconnection in an extreme case. Therefore, in the second embodiment, these abnormalities are diagnosed by recording the precharge time for charging the capacitor 40.

  Therefore, in the second embodiment, the program executed in the relay control device 30 is changed from the relay control sequence program shown in FIG. 3 to the relay control and diagnosis sequence program shown in FIG.

  In the program of the relay control and diagnosis sequence of FIG. 6, in the first step S10, the recording of the precharge elapsed time (precharge time) Tp of the capacitor 40 is started, and in step S11, the precharge relay 20 is turned on to electromagnetically. The coil 20b is energized, and charging of the capacitor 40 from the battery 1 via the precharge resistor 21 is started.

  Next, in step S12, the output voltage V1 of the battery 1 and the charging voltage V2 of the capacitor 40 based on the signals from the voltage sensors 60 and 61 are monitored, and the precharge time Tp is recorded and monitored. In step S13, it is checked whether the voltage difference (V1-V2) has become equal to or less than the threshold value Vs.

  As a result, if Vs <(V1-V2), the process proceeds from step S13 to step S19 to check whether the precharge time Tp has exceeded the set time T2. The set time T2 is mainly a time for diagnosing an abnormality of the precharge resistor 21, and as an upper limit value of the charge time allowed for an increase in resistance value due to variations in resistance value or deterioration of the precharge resistor 21. It is set by simulation or experiment, and is stored in advance in the ROM 32 of the relay control device 30 as fixed data.

  In step S19, if Tp ≦ T2, the process returns to step S12 to continue monitoring the voltages V1, V2 and the precharge time Tp, and Vs ≧ (V1−V2) without the precharge time Tp exceeding the set time T2. ), The process proceeds from step S13 to step S14. In step S14, the recording of the precharge time Tp is ended, and in step S15, it is checked whether or not the final precharge time Tp is less than the set time T1. The set time T1 is mainly a time for diagnosing an abnormality of the capacitor 40. As a lower limit value of a charging time allowed for a capacity decrease or the like due to a variation in capacity or deterioration of the capacitor 40, a simulation or an experiment is performed in advance. And is stored in advance in the ROM 32 of the relay control device 30 as fixed data.

  The diagnosis based on the set time T1 can be applied to the case where the precharge resistor 21 is short-circuited or close to a short-circuit although the frequency of occurrence is small.

  If the precharge time Tp is equal to or longer than the set time T1 (Tp ≧ T1) as a result of the diagnosis by the set time T1, the diagnosis is normal and the process proceeds from step S15 to step S16, and the main relay 10 is turned on. Energize the electromagnetic coil 10b. By energizing the electromagnetic coil 10b of the main relay 10, the relay contact 10a is closed, the precharge resistor 21 is short-circuited, and the battery 1 and the capacitor 40 (and the load 50) are directly connected. Then, in step S17, the precharge relay 20 is turned off, and this sequence ends normally.

  On the other hand, if the precharge time Tp is longer than the set time T2 in step S19 (Tp> T2), or if the precharge time Tp is shorter than the set time T1 in step S15 (Tp <T1), the precharge resistor 21 Or it diagnoses that the capacitor | condenser 40 is abnormal and progresses to step S20, the precharge relay 20 is turned off, and the connection of the battery 1 and the capacitor | condenser 40 (and load 50) is cut | disconnected. In step S21, a fail signal is output to notify the occurrence of an abnormality, and this sequence ends abnormally.

  In the second embodiment, when the precharge resistor 21 is deteriorated and the resistance value is increased to be disconnected or close to a disconnected state, or when the capacitor 40 is deteriorated and the capacity is decreased, and a capacity drop occurs. However, it is possible to detect the abnormality and protect the main relay 10, the precharge relay 20, and various devices of the load. That is, since the abnormality diagnosis function is provided in addition to the control function for the main relay 10 and the precharge relay 20, not only the contact welding of the main relay 10 can be prevented but also the reliability of the entire system can be improved.

The circuit block diagram of a power supply system in connection with 1st Embodiment of this invention. Same as above, functional configuration diagram of control device Same as above, flow chart of relay control sequence Same as above, circuit configuration diagram showing a modification of the power supply system The circuit block diagram which shows the other modification of a power supply system same as the above Flowchart of relay control and diagnosis sequence according to the second embodiment of the present invention.

Explanation of symbols

1 Battery 10 Main Relay 20 Precharge Relay 21 Precharge Resistor 30 Relay Control Device 40 Capacitor 50 Load V1-V2 Voltage Difference Vs Threshold

Claims (3)

A control device for a vehicle power supply system having a main relay for intermittently connecting a main power supply and a load of the vehicle, and a precharge relay connected in parallel to the main relay via a precharge resistor,
A comparison means for obtaining a voltage difference between the voltage on the main power supply side and the voltage on the load side, and comparing the voltage difference with a preset threshold value;
When the voltage difference exceeds the threshold value as a result of comparison by the comparison means, the relay contact of the precharge relay is closed with the relay contact of the main relay opened, and the main power supply side and the load When the voltage difference is equal to or less than the threshold value, the relay contact of the precharge relay is opened and the relay contact of the main relay is closed to connect the main power source. A control device for a vehicle power supply system, comprising: a relay control means for connecting a load side and the load side.   The elapsed time after the relay contact of the precharge relay is closed is recorded, and the elapsed time when the voltage difference is less than or equal to the threshold is less than a first set time, or the voltage difference is 2. The diagnostic apparatus according to claim 1, further comprising: a diagnosis unit configured to determine that an abnormality has occurred in the load side or the precharge resistor when an elapsed time in a state exceeding the threshold exceeds a second set time. The vehicle power supply system control device described.   A capacitor for smoothing a voltage from the main power supply is connected to a front stage side of the load, and a difference between an output voltage of the main power supply and a charging voltage of the capacitor is the voltage difference. The control apparatus of the power supply system for vehicles of 1 or 2.

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