JP2001185228A - Electric power supply equipped with battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the reduction of the output power, in the case where some parts of a battery have deteriorated, prevent evolution of heat with a deteriorated battery, and facilitate the maintenance. SOLUTION: The electric power supply is connected with each of a battery module 1, which is connected in parallel with each other where a current detector circuit 2 and a switch 3 are connected in series. The output of the current detector circuit 2 is calculated by a control circuit 4, with which the switch 3 is controlled. The control circuit 4 cuts off current by making the switch S to off, which is connected with the battery module 1 with which the direction of lowing current reverses from the normal direction, or the current unbalance exceeds the set value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power supply mainly used for a hybrid car.

[0002]

2. Description of the Related Art A power supply device containing a plurality of batteries has batteries connected in series or in parallel. A device with batteries connected in parallel can increase the output current, and a power supply with batteries connected in series can increase the output voltage. Currently, a hybrid car put into practical use has a power supply device in which batteries are connected in series. In this power supply device, since the same current flows through all the batteries, the current does not become unbalanced. However, since all the batteries are connected in series, this power supply device has a disadvantage that when one of the batteries is deteriorated and the internal resistance is increased, the overall output is significantly reduced. This is because one battery having an increased internal resistance reduces the overall output current.

On the other hand, in a power supply device in which batteries are connected in parallel, even if one of the batteries is deteriorated and, for example, the internal resistance is increased, a decrease in the output of the entire power supply device is extremely small. . Therefore, there is a feature that any of the batteries can be sufficiently used in a deteriorated state.

[0004] In a power supply device used in an application in which a considerably large number of batteries, such as 100 or more, are incorporated to increase the output power, for example, a hybrid car or the like, a power supply device is used as a power supply when one of the batteries is deteriorated. Availability is a very important property. That is, as the number of built-in batteries increases, the probability of deterioration of any one of the batteries increases, and this main power supply is used for repair maintenance when one battery deteriorates and becomes unusable. Is extremely time-consuming.

[0005]

In a power supply device in which batteries are connected in parallel, even if the batteries deteriorate and the internal resistance increases, the output power of the entire device does not decrease much. This is because a deteriorated battery does not limit the output of a battery that does not deteriorate.
However, battery deterioration does not necessarily mean that the internal resistance increases. For example, it may be deteriorated by an internal short circuit. The output voltage of the battery that has been internally short-circuited decreases, and current flows in the opposite direction from the other batteries connected in parallel. Since the internal resistance of a battery that is internally short-circuited is extremely small, the current flowing in the reverse direction is considerably large, and heat may be generated, which may be dangerous.

The present invention has been developed with the object of solving such disadvantages. An important object of the present invention is to reduce a decrease in output power when any battery is deteriorated, An object of the present invention is to provide a power supply device that can be used safely by preventing heat generation and the like of a deteriorated battery and can be further simplified in maintenance.

[0007]

The power supply device of the present invention comprises a plurality of battery modules 1 connected in parallel to each other, and a current detection circuit 2 for detecting the current of each battery module 1.
And the switch 3 connected in series with each battery module 1 and the output of the current detection circuit 2
And a control circuit 4 for controlling When the direction of the current is opposite to the normal direction, or when the deteriorated battery module 1 whose current imbalance is larger than the set value is detected, the control circuit 4 switches the switch 3 connected to the deteriorated battery module 1. Is turned off to interrupt the current.

The battery module 1 is, for example, one in which a plurality of secondary batteries 6 are connected in series. Further, in the power supply device of the present invention, preferably, a temperature sensor 7 is provided for each battery module 1, and the temperature sensor 7 is connected to the control circuit 4. In this power supply device, the temperature of each battery module 1 is detected by a temperature sensor 7, and the switch 3 connected to the battery module 1 whose battery temperature has become abnormally high is turned off, whereby the abnormally high temperature of the battery module 1 is detected. 1 can be disconnected.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. However, the embodiments described below exemplify a power supply device for embodying the technical idea of the present invention, and the present invention does not specify the power supply device as follows.

Further, in this specification, in order to make it easy to understand the claims, the numbers corresponding to the members shown in the embodiments will be referred to as “claims” and “ In the column of “means”.
However, the members described in the claims are not limited to the members of the embodiments.

The power supply device of the present invention is most suitable for a hybrid car that runs on both an engine and a motor. Hereinafter, a specific example in which the power supply device of the present invention is used for a hybrid car will be described in detail. However, the power supply device of the present invention is not limited to a hybrid car, but can be used for any purpose other than a hybrid car and for any purpose that increases the output current. In a hybrid car, a generator is driven by an engine to charge a battery, or a battery is charged by a so-called regenerative brake that drives the generator with energy when the vehicle stops. The charged battery of the power supply device drives the motor to drive the automobile.

The power supply device shown in FIG. 1 has a plurality of battery modules 1 connected in parallel with each other, a current detection circuit 2 for detecting the current of each battery module 1, and a series connection with each battery module 1. And a control circuit 4 that calculates the output of the current detection circuit 2 and controls the switch 3. The power supply device shown in FIG.
The current detection circuit 2 and the switch 3 are connected in series with
It is connected between the negative output terminals 5. +-Output terminal 5
, A plurality of battery modules 1 are connected in parallel.

The battery module 1 has a plurality of secondary batteries 6 connected in series. The secondary battery 6 is a rechargeable battery such as a nickel-hydrogen battery, a nickel-cadmium battery, or a lithium ion secondary battery. However, the battery module may include one secondary battery. Further, the battery module may have a structure in which a plurality of secondary batteries are connected in parallel, or a structure in which a plurality of secondary batteries are connected in parallel is connected in series.

The battery module 1 has a built-in temperature sensor 7. A battery module incorporating a plurality of secondary batteries is provided with a temperature sensor on the surface of each secondary battery to detect the temperature of each battery, or by providing one temperature sensor 7 in the battery module 1 and The temperature of the entire module 1 is detected. The temperature sensor 7 is a thermistor, a varistor, a PTC, or the like, whose internal resistance changes according to the temperature. Each temperature sensor 7 is connected to the control circuit 4 and inputs a signal of the detected battery temperature to the control circuit 4.

The current detection circuit 2 detects the magnitude and direction of the current flowing through the battery module 1. Current detection circuit 2
Includes a current detection resistor 8 connected in series with the battery module 1 and a differential amplifier 9 for amplifying a voltage generated at both ends of the current detection resistor 8, as shown in FIG. The current detection circuit 2 detects the magnitude of the current flowing through the battery module 1 based on the magnitude of the output voltage of the differential amplifier 9,
The direction of the current flowing through the battery module 1 is detected in the +/− direction of the output voltage of the differential amplifier 9.

The switch 3 is a semiconductor switching element such as a transistor or FET, or a relay. When the switch 3 is turned on, it is necessary to supply both the charging current and the discharging current to the battery module 1. The semiconductor switching element controls a current flowing in one direction. Therefore, in a device using a switch as a semiconductor switching element, two switching elements are connected in parallel in opposite directions.

The control circuit 4 comprises a battery control unit 10 and a vehicle control unit 11. The signals of the current detection circuit 2 and the temperature sensor 7 are input to the battery control unit 10. The battery control unit 10 calculates a signal input from each current detection circuit 2 and the temperature sensor 7 and outputs an abnormal signal to the vehicle control unit 11. The abnormal signal includes a signal that specifies the battery module 1.

The battery control unit 10 detects whether a reverse current is flowing through any one of the battery modules 1 or detects an imbalance in the current flowing through the battery module 1. To detect if it is higher. When a reverse current flows through any one of the battery modules 1 or when the imbalance of the current becomes larger than a set value or becomes higher than a set temperature, an abnormal signal is output to the vehicle control unit 11.

The battery control unit 10 outputs an abnormal signal of the battery module 1 as follows in the flowchart shown in FIG.

[Step n = 1] The current of each battery module 1 is measured. The current of each battery module 1 is detected by a current detection circuit 2, and a signal for detecting the current is sent from the current detection circuit 2 to the battery control unit 10.
Is input to The battery control unit 10 detects the current of the battery module 1 from the input signal.

[Step n = 2] It is detected whether the direction of the current flowing through all battery modules 1 is the same, that is, whether there is a battery module whose current is opposite to the normal direction. If the direction of the current of any of the battery modules is reversed, the process jumps to the step of n = 5, and outputs an abnormal signal specifying the battery module whose current direction is reversed to the vehicle control unit 11.

[Step n = 3] If the directions of the currents flowing through all the battery modules 1 are the same, the process proceeds to this step.
It is determined whether the current difference is within the set range. When the current difference of any of the battery modules becomes larger than the set range and the current value of the battery module becomes larger than the set value and becomes unbalanced, the process jumps to the step of n = 5, and the current becomes unbalanced. An abnormal signal specifying the battery module is output to the vehicle control unit 11.

[Step n = 4] When the current imbalance of all the battery modules 1 is within the set range, the process proceeds to this step to detect the battery temperature imbalance. When the battery temperature of any of the battery modules becomes higher than the set value by more than the other battery modules, the process jumps to the step of n = 5, and sends an abnormal signal specifying the battery module whose temperature has become abnormally high to the vehicle control. Output to the unit 11.

The difference between the battery temperatures is detected by comparing the average value of all battery temperatures with the battery temperature of each battery module 1, and the battery temperature of any one of the battery modules is higher than the average temperature by a set value or more. Then, it is determined that the battery temperature has become unbalanced. For example, when the battery temperature becomes higher than the average temperature by 20 ° C. or more, it is determined that the battery temperature has become unbalanced.

When the battery temperature of each battery module 1 is within the set range, the process jumps to the step of n = 1, and n = 1 until one of the battery modules becomes abnormal.
Steps 1-4 are looped.

When the current of any one of the battery modules is reversed or the current value or the battery temperature becomes unbalanced, the battery control unit 10 causes the battery control unit 10 to output an abnormal signal specifying the abnormal battery module. Is output to the vehicle control unit 11. However, the power supply device of the present invention compares the magnitude of the reverse current with a set value when a battery module in which the direction of the current is reversed is found, and only when the reverse current is larger than the set value, An abnormal signal for specifying the battery module can also be output. When the direction of the current of any of the battery modules is reversed, the temperature of the battery module in which the reverse current is flowing is compared with the set temperature, and an abnormal signal is generated only when the battery temperature is higher than the set value. You can also output.

The vehicle control unit 11 controls the switch 3 with the abnormal signal input from the battery control unit 10 and turns off the switch 3 of the battery module 1 specified by the abnormal signal. The battery module 1 connected to the switch 3 that has been turned off is disconnected from the output terminal 5 of the power supply device.

FIG. 4 shows a vehicle control unit 11.
Shows a flowchart for controlling the switch 3. In this flowchart, switch 3 is performed in the following steps.
Control. [Step n = 1] An abnormal signal of a specific battery module is input from the battery control unit 10. [Step n = 2] Limit the output of the vehicle. The output limitation, for example, limits the maximum current supplied from the power supply to the motor to a small value. The limitation of the current is controlled by, for example, a duty ratio for switching on and off a switching element supplied from the power supply device to the motor.

[Step n = 3] The switch 3 connected to the battery module specified by the abnormal signal is turned off to disconnect the abnormal battery module from the output terminal 5.

[0030]

The power supply device equipped with the battery according to the present invention can be used effectively with a small decrease in output power even when one of the battery modules connected in parallel is deteriorated and cannot be used. There is. This is a particularly important characteristic for a power supply device in which many batteries are connected in series. If any one of the batteries deteriorates, the power supply will become unusable.
There is a disadvantage that the usable life is substantially shortened.
This is because, in a power supply device having a large number of batteries, the lifespan of the batteries is significantly unbalanced, and it is impossible to eliminate batteries having a short life.

Further, the power supply device of the present invention has a feature that since the deteriorated battery is separated and put into a state of non-use, it is possible to reliably prevent adverse effects such as the abnormal battery being heated to a high temperature and use it safely. . In addition, since the deteriorated battery is separated and used, there is a feature that even if there is a deteriorated battery, it can be used and maintenance can be simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram of a power supply device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a current detection circuit built in the power supply device of FIG. 1;

FIG. 3 is a flowchart showing steps of detecting an abnormal battery module by a battery control unit.

FIG. 4 is a flowchart showing steps in which a vehicle control unit controls a switch based on an abnormal signal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Battery module 2 ... Current detection circuit 3 ... Switch 4 ... Control circuit 5 ... Output terminal 6 ... Secondary battery 7 ... Temperature sensor 8 ... Current detection resistor 9 ... Differential amplifier 10 ... Battery control unit 11 ... Car control unit

Claims (3)

[Claims] A plurality of battery modules (1) connected in parallel with each other, a current detection circuit (2) for detecting a current of each battery module (1), and a series connection with each battery module (1). And a control circuit (4) for calculating the output of the current detection circuit (2) and controlling the switch (3), and each of the battery modules ( The current flowing in 1) is detected by the current detection circuit (2), and the switch connected to the battery module (1) in which the current direction is opposite to the normal direction or the current imbalance is larger than the set value (3) A power supply device including a battery in which a control circuit (4) switches from on to off. 2. The power supply device according to claim 1, wherein the battery module (1) includes a plurality of secondary batteries (6) connected in series. 3. Each battery module (1) is provided with a temperature sensor (7), the temperature sensor (7) is connected to a control circuit (4), and the control circuit (4) is connected to the battery module (1). A power supply device comprising the power supply according to claim 1, which controls the switch (3) by detecting a temperature of the power supply.