JP4143267B2 - Vehicle power supply device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle power supply apparatus having a high voltage battery charged by a generator and a low voltage battery charged by electric power supplied from the high voltage battery via a voltage converter.
[0002]
[Prior art]
Conventionally, it has been proposed and put to practical use to improve fuel efficiency and reduce exhaust gas by stopping the engine when the vehicle stops under a predetermined condition and restarting the engine when the vehicle starts. .
[0003]
A vehicle that performs such automatic engine stop / restart has a motor generator in order to restart the engine and generate necessary power. When starting the vehicle, the engine is restarted using the motor generator as a motor, and the vehicle is driven by the output of the motor generator. For this reason, the motor generator is driven with a large electric power, and a high voltage battery having a voltage of about 36V is used for this purpose. On the other hand, in order to drive various in-vehicle accessories, a low voltage battery having a voltage of about 12V is used. Therefore, in a vehicle that performs automatic engine stop / restart, two batteries, a normal high voltage battery and a low voltage battery, are mounted.
[0004]
The high-voltage battery is charged with electric power generated when the motor generator is operated as a generator. On the other hand, charging of the low voltage battery is performed by converting electric power from the high voltage battery into a voltage for charging the low voltage battery by a DC / DC converter which is a power converter.
[0005]
[Problems to be solved by the invention]
Thus, for charging the low voltage battery, the power from the high voltage battery is converted to a low voltage by the power converter and used. However, in the power converter, when a short circuit occurs, the high-voltage side voltage is output to the low-voltage side as it is, and there is a problem that a large current flows through the low-voltage battery and various auxiliary devices connected to the low-voltage side.
[0006]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a vehicle power supply device that can perform an appropriate operation even when a power converter is short-circuited.
[0007]
[Means for Solving the Problems]
The present invention, by a generator, a high voltage energy storage means to be charged, the high voltage energy storage means and is electrically connected via a power converter, it is charged via the power converter from the high voltage energy storage means, the low A low-voltage storage means for supplying power to the voltage system load; a short-circuit fault detection means for detecting a short-circuit fault in the power converter; and when the short-circuit fault in the power converter is detected by the short-circuit fault detection means, the power generation possess a generator control means for stopping the power generation of the machine, and at the time of detection of the short-circuit failure, as well as stopping the power generation of the generator, since the low voltage energy storage means is connected to the low-voltage load, A high voltage supplied to the load of the low voltage system is prevented from being applied .
[0008]
The present invention also provides a high voltage storage means to be charged by a generator, and is electrically connected to the high voltage storage means via a power converter and charged from the high voltage storage means via the power converter. , a low voltage energy storage unit that provides power to a load of the low voltage system, a short-circuit failure detecting means for detecting a short circuit fault of the power converter, when a short circuit fault of the power converter is detected by the short-circuit failure detecting means , have a, and generator control means for reducing the power generation amount of the generator, when the detection of the short circuit fault, while reducing the generation amount of the generator, a low voltage energy storage means is connected to the low-voltage load Therefore, it is possible to prevent a high voltage supplied to the load of the low voltage system from being applied .
[0009]
Thus, according to the present invention, when a short circuit fault occurs in the power converter, the power generation of the generator is stopped or the power generation amount of the generator is reduced. Thereby, the low voltage | pressure side apparatus connected to the output of a power converter can be protected. In particular, reliable protection can be achieved by stopping the power generation, and the operation of the low-pressure side device can be maintained for a long time by reducing the amount of power generation.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The high-voltage and low-voltage power storage means is, for example, a battery or a capacitor.
[0011]
FIG. 1 is a block diagram showing the configuration of the power supply apparatus of the present embodiment. The motor generator 1 is mechanically connected to the output shaft of the engine. When the motor generator 1 is driven as a motor, the motor generator 1 is started by rotating the engine and generates a driving force for traveling the vehicle. Further, when the engine is driven, it operates as a generator and generates desired generated power.
[0012]
The motor generator 1 is connected to a high voltage battery 3 as a high voltage storage means via an inverter 2. Inverter 2 converts alternating current generated in motor generator 1 into direct-current power to charge high-voltage battery 3, and converts direct-current power from high-voltage battery 3 into predetermined alternating-current power to drive motor generator 1. That is, the motor generator 1 is operated as a generator, the generated power is supplied to the high voltage battery 3, the DC power from the high voltage battery 3 is converted into AC power and supplied to the motor generator 1, and this is operated as a motor. . The motor generator 1 has, for example, a three-phase coil, and the inverter 2 has a series connection of two switching transistors connected between the power supply grounds corresponding to the coils of each phase. That is, power conversion is performed by turning on and off a total of six switching transistors.
[0013]
An ECU (electronic control unit) 4 is connected to the inverter 2, and the ECU 4 controls switching of the switching transistor in the inverter 2 and performs predetermined power conversion.
[0014]
A DC / DC converter 5 that is a power converter is connected to the high voltage battery 3. This DC / DC converter 5 controls the voltage on the output side by switching of a normal transistor, and outputs charging power of a low voltage battery 6 as a low voltage storage means. A low voltage battery 6 is connected to the output of the DC / DC converter 5 and is charged by a charging current from the DC / DC converter 5. In addition, it can replace with a battery and a capacitor | condenser can also be employ | adopted as an electrical storage means.
[0015]
Furthermore, a short circuit detector 7 is connected to the output terminal 5a of the DC / DC converter 5 and the terminal 6a of the low voltage battery. Further, the output terminal 5a of the DC / DC converter 5 and the terminal 6a of the low voltage battery are connected by a cable 8, and the voltage of both terminals 5a and 6a is detected. Therefore, the short circuit detector 7 can detect a voltage drop in the cable 8 from the voltages at both terminals 5a and 6a.
[0016]
In such a device, during normal driving of the vehicle, the motor generator 1 operates as a generator and charges the high voltage battery 3 with the generated power. Here, the ECU 4 controls the drive of the inverter 2 so that the output voltage of the high voltage battery 3 on the output side of the inverter 2 becomes a predetermined value, and feedback-controls the electric power generated by the motor generator 1.
[0017]
The DC / DC converter 5 controls its own output voltage so that the voltage of the low voltage battery 6 becomes a predetermined value.
[0018]
When the vehicle is stopped, the fuel to the engine is cut when a predetermined low speed is reached. Note that the fuel cut is temporarily stopped immediately before the vehicle is stopped to prevent vibrations. While the vehicle is stopped, the fuel is cut off and when the accelerator is depressed, the ECU 4 drives the inverter 2 to rotate the engine by the motor generator 1 and drive the vehicle. Then, when the engine speed reaches a predetermined speed, the fuel supply to the engine is resumed, and normal driving is resumed.
[0019]
Then, at the time of power generation in the motor generator 1 in such an operation, the processing shown in FIG. 2 is performed. First, the short circuit detector 7 determines whether the output current of the DC / DC converter 5 is abnormal (S11). That is, the short circuit detector 7 determines that the voltage difference between the output terminal 5a of the DC / DC converter 5 and the terminal 6a of the low voltage battery 6 is equal to or greater than a predetermined value. This is because, if the DC / DC converter 5 is normal, the output current from here is the charging current of the low-voltage battery 6 and the current to the auxiliary equipment connected thereto, and does not increase to a certain extent. . Note that the amount of current may be detected by an ammeter.
[0020]
If the determination in S11 is NO, it is determined that there is no abnormality in the output current of the DC / DC converter 5 and there is no short-circuit failure, and the determination in S11 is repeated.
[0021]
On the other hand, if the determination in S11 is YES, it is determined whether or not the output voltage of the DC / DC converter 5 is greater than or equal to the command value (S12). In this determination, if the voltage value is not high, it is determined that the DC / DC converter 5 is not short-circuited, and the process returns to the determination of S11. On the other hand, if the determination in S12 is YES, it is determined that a short circuit failure has occurred in the DC / DC converter 5. This is because if the DC / DC converter 5 is normal, its output voltage should basically be the same as the command value.
[0022]
If YES in S12, the ECU 4 controls the inverter 2 to stop the power generation by the motor generator 1 (S13). As a result, the supply of the generated power to the low voltage battery 6 is stopped, and the supply power to the low voltage battery 6 side is prevented from becoming a large power, so that the low voltage battery 6 and auxiliary equipment connected thereto can be reduced. The voltage side device can be protected.
[0023]
In S11 described above, when the output current of the DC / DC converter 5 is very large, a short circuit failure of an auxiliary machine connected to the DC / DC converter 5 may be considered. Therefore, in such a case, it is preferable to stop the output of the DC / DC converter 5 or to disconnect the low voltage side battery 6 from the auxiliary machine.
[0024]
In the above embodiment, power generation by the motor generator 1 is stopped in S13. However, instead of this, it is also preferable to reduce the power generation amount of the motor generator 1. That is, as shown in FIG. 3, when short circuit detector 7 detects a short circuit failure in DC / DC converter 5 (YES in S 11 and S 12), ECU 4 controls inverter 2 to generate power generated by motor generator 1. Decrease. As a result, the low voltage side devices can be protected and the operation of the low voltage side devices can be maintained for a relatively long time. That is, since the amount of power generation is small, sufficient power is not supplied to the low-voltage side device, but the minimum operation is maintained for a long time, and so-called limp foam is achieved.
[0025]
The power generation amount control in S13 is preferably performed according to a predetermined pattern. For example, control is performed so that the voltage difference between the output terminal 5a of the DC / DC converter 5 and the low voltage battery 6 is equal to or less than a predetermined value. be able to. It is also preferable to provide an ammeter or the like and control the amount of power generation with this ammeter so that the amount of current becomes a predetermined value.
In addition, since the battery has the lowest impedance among the 12V system loads, it takes some time (several minutes to several tens of minutes) to increase the voltage of the 12V battery. Therefore, 36V is a load on the 12V side (auxiliary machine) ) Is not directly applied.
[0026]
【The invention's effect】
As described above, according to the present invention, when a short-circuit failure occurs in the power converter, the power generation of the generator is stopped or the power generation amount of the generator is reduced. Thereby, the low voltage | pressure side apparatus connected to the output of a power converter can be protected. In particular, reliable protection can be achieved by stopping the power generation, and the operation of the low-pressure side device can be maintained for a long time by reducing the amount of power generation.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration of an apparatus.
FIG. 2 is a flowchart showing an operation.
FIG. 3 is a flowchart showing another example of the operation.
[Explanation of symbols]
1 motor generator, 2 inverter, 3 high voltage battery, 4 ECU, 5 DC / DC converter, 6 low voltage battery, 7 short circuit detector, 8 cable.

Claims (2)

High voltage storage means to be charged by a generator;
Low voltage power storage means electrically connected to the high voltage power storage means via a power converter, charged from the high voltage power storage means via the power converter, and supplying power to a low voltage system load ;
A short-circuit fault detection means for detecting a short-circuit fault of the power converter;
When a short-circuit failure of the power converter is detected by the short-circuit failure detection means, a generator control means for stopping the power generation of the generator;
I have a,
At the time of detecting the short-circuit fault, the generator stops power generation, and the low voltage storage means is connected to the low voltage system load, so that the high voltage supplied to the low voltage system load is applied. power supply apparatus for a vehicle, characterized in that to prevent the that. High voltage storage means to be charged by a generator;
The high voltage energy storage means and is electrically connected via a power converter, it is charged via the power converter from the high voltage energy storage means, a low-voltage energy storage unit that provides power to a load of the low voltage system,
A short-circuit fault detection means for detecting a short-circuit fault of the power converter;
When a short-circuit fault of the power converter is detected by the short-circuit fault detection means, a generator control means for reducing the power generation amount of the generator;
I have a,
At the time of detecting the short-circuit fault, the power generation amount of the generator is reduced, and a low voltage storage means is connected to the low voltage system load, so that a high voltage supplied to the low voltage system load is applied. A power supply device for a vehicle, characterized in that it is prevented .

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