CN1165103C - An automatic equalizing charging device for series battery packs - Google Patents

Abstract

The present invention is an automatic balanced charging device for a series battery pack, which consists of a series battery pack to be charged (1), a battery voltage signal real-time acquisition and isolation circuit (2), a main control circuit board (3), an inverter charging Power supply (4), battery voltage inspection and display circuit (6), temperature sensor (7), isolation drive circuit (8) and the existing power switch (11) and bypass shunt network (12) formed by it In the balanced charging technology, the discharge network (5) composed of a MOS tube (9) and a power resistor (10) in series is used to replace the power switch (11) in the prior art and the bypass shunt network (12) formed by it, to Fast, safe and reliable charging of the series battery pack (1) is realized, and automatic equalization of the series battery pack (1) is achieved.

Description

An automatic equalizing charging device for series battery packs

technical field

The invention relates to an automatic equalizing charging device for series battery packs in various fields such as electric vehicles.

Background technique

Batteries are widely used in various fields, especially in electric vehicles in recent years, power batteries such as lithium-ion batteries, nickel-metal hydride batteries, etc. are regarded as one of the key components. When charging these battery packs working in series, how to ensure fast and efficient automatic equalization charging of the battery packs during the charging process is a key to ensure the safety and reliability of lithium-ion batteries and nickel-metal hydride batteries and to give full play to their performance technology.

In a known series battery pack charging device, the DC or pulse output of the charging power supply charges the series battery pack, and the output voltage and current are adjustable. This device cannot detect and control the terminal voltage of the single battery, so that the battery pack The balance of the battery is poor, which affects the service life and performance of the battery.

Another known balance charging device for battery packs in series is to use an independent charging system for each single battery, or to use a charging power supply with multiple sets of DC outputs, and each set of DC outputs to charge a single battery respectively. Charge. This method is simple and reliable, but when the number of single cells in the battery pack is large, the method is too complicated to implement and has a large volume.

Another known balancing charging device for series-connected battery packs uses a set of charging power sources to simultaneously charge the series-connected battery packs, and monitors the state of each single battery in real time. Charging stops when any single battery reaches the preset charging state. There are two main ways to stop charging: one way is to isolate the battery that has reached the preset charging state, and a contactor or power electronic switch can be used, but this way will connect multiple contactor contacts in the series battery pack Or the electronic switch will inevitably affect the working reliability of the series battery pack, and the access to the power electronic switch will also consume a large amount of power, significantly reduce the working efficiency of the battery pack, and greatly increase the volume of the series battery pack. The second method is to bypass and shunt the charging current of the single battery that reaches the preset charging state to avoid overcharging. This method requires more precise control of the bypass current and sacrifices a certain charging efficiency.

Contents of the invention

The purpose of the present invention is to provide an automatic equalizing charging device for battery packs connected in series, which is fast in charging speed and safe and reliable compared with the prior art.

The invention is a novel automatic equalizing charging device for series battery packs. According to the present invention, the power switch in the prior art and the bypass shunt network composed of it are removed, and a discharge network is used instead. Each output terminal of the isolated drive circuit is connected to the control terminal of the MOS tube, the positive pole of the single battery of the series battery pack is connected to the input terminal of the MOS tube, the output terminal of the MOS tube is connected to the power resistor, and the other end of the power resistor is connected to the On the negative terminal of the single cells of the series battery pack.

Description of drawings

Fig. 1 is a block diagram of a series-connected battery pack equalizing charging circuit with a power switch and a bypass shunt network composed of it in the prior art.

Fig. 2 is a block diagram of an automatic equalizing charging device for series battery packs of the present invention.

Detailed ways

In Fig. 1, which shows the circuit block diagram of an automatic equalizing charging device for series-connected battery packs in the prior art, the series-connected battery pack 1 is charged by an inverter charging power source 4 with only one set of positive and negative DC output terminals. When charging, each unit of the series-connected battery pack The current and voltage signal of the battery is fed back to the real-time acquisition and isolation circuit 2 of the battery voltage signal, and the signal is input to the main control circuit board 3 through the real-time acquisition and isolation circuit 2 of the battery voltage signal. The temperature signal is also input to the main control circuit board, the main control circuit board 3 controls the battery voltage inspection and display circuit 6 to display the voltage of each single battery, and its control signal is input to the charging power supply 4 and the isolation drive circuit 8, and the isolation The drive circuit 8 inputs the signal to the power switch 11 connected in parallel with the series battery pack and the bypass shunt network 12 formed by it, thereby controlling the output current and output voltage of the charging power supply, and controlling the output of the single battery that has reached the preset charging state. The charging current is shunted to avoid overcharging.

The automatic equalization charging device for series battery packs of the present invention consists of a set of series battery packs 1 to be charged, a real-time acquisition and isolation circuit 2 for battery voltage signals, a main control circuit board 3, an inverter charging power supply 4, a discharge network 5, and a battery The voltage inspection and display circuit 6, the temperature sensor 7, and the isolation driving circuit 8 are composed.

The battery pack to be charged in series can be a lithium-ion rechargeable battery or a nickel-metal hydride battery. The capacity of each single battery can be hundreds of milliamp hours or hundreds of ampere hours, and the number of single cells in the battery pack is not limited.

The battery voltage signal real-time collection and isolation circuit 2 collects the terminal voltage of each single battery through wires, and sends it to the main control circuit board 3 after being amplified and photoelectrically isolated.

The main control circuit board 3 is composed of a microprocessor and a logic control circuit. It receives the battery voltage signal and collects and isolates the terminal voltage signal of each single battery in real time from the circuit 2, as well as the temperature signal of the battery pack from the temperature sensor 7. , control the output current and output voltage of the charging power supply, and control the discharge network to discharge the battery cells with higher terminal voltage values in an appropriate amount, and at the same time control the battery voltage inspection and display circuit 6 to display the terminal voltage of each single battery.

The charging power supply is an inverter charging power supply. The main power device uses an IGBT (insulated gate bipolar transistor) module. The main circuit is composed of an IGBT inverter circuit. The output of the charging power supply can be realized by feedbacking the output current and voltage External characteristic control, so as to realize the control of charging current and charging voltage. The output current and voltage of the charging power supply depend on the state of the battery pack.

The parallel discharge network 5 circuit is composed of MOS transistor 9 and series connected power resistor 10, and the main control circuit board 3 isolates and drives the switch MOS transistor to control the discharge of the discharge circuit. The size of the discharge current is determined by the size of the power battery 10 . The battery voltage inspection and display circuit 6 detects the voltage of each single battery through the inspection circuit, and displays it on a nixie tube or a liquid crystal display.

The battery pack in series can be a lithium-ion rechargeable battery or a nickel-metal hydride battery. As far as a certain battery pack is concerned, the maximum charging current I _M refers to the maximum current that the battery pack can withstand. Under this current, the temperature rise of the battery pack will not be too high and the performance will not be damaged; the highest end voltage V _M refers to the single The highest voltage that the battery can be charged to.

The specific charging procedure of this program is as follows:

First, the main control board controls the output of the charging power supply to charge the entire battery pack in series with the maximum charging current I _M. During the charging process, the terminal voltage of each battery is monitored. When a single battery with the highest terminal voltage is detected When the terminal voltage of V is close to the highest terminal voltage V _M , the main control board will discharge the single battery with higher opposite terminal voltage slightly, and the battery with lower opposite terminal voltage will continue to be charged. At this time, the charging current can be appropriately reduced. It is ensured that the terminal voltages of the batteries in the series battery pack rise synchronously, and are finally charged to the highest terminal voltage V _M at the same time, so as to realize balanced charging of the battery pack.

In the charging process of the present invention, the voltage of each single cell of the battery pack rises synchronously, which realizes the equalization of the battery pack, and at the same time maintains a relatively high charging current and high charging efficiency during the charging process. The charging process is intelligent and automated.

The final charging voltage set during the charging process is the highest voltage V _M of the battery. When the battery voltage is detected to be higher than the highest voltage V _M , it will be discharged, so there will be no overcharging, ensuring the safety of the charging process .

During the charging process, the battery discharge is carried out by connecting the MOS switch tube in series with the power resistor.

During the charging process, in order to ensure the safety of the battery pack, the temperature of the battery pack must be monitored. A temperature sensor is set in each battery combination to detect the temperature of each battery combination. The temperature sensing signal is input to the main control board, and the temperature of the battery is detected in real time during the charging process. When the temperature of any battery combination exceeds the rated charging temperature, the charging is suspended (the output of the charging power supply is turned off).

The characteristics of the invention: (1) When charging the battery packs connected in series, only one set of inverter charging power sources with positive and negative DC output terminals directly charges the series battery packs, which is similar to the method in which multiple sets of DC outputs are used by similar chargers. Compared with the present invention, the volume is small, the weight is light, and the charging efficiency is high. (2) During the charging process, the discharge network is used to discharge the single battery with a higher terminal voltage in an appropriate amount, so that the voltage of each single battery in the battery pack increases synchronously and is sufficient at the same time to achieve automatic balance of the battery pack in series. (3) The final charging voltage set in the charging process is the highest terminal voltage V _M of the battery. When the battery voltage is detected to be higher than the highest terminal voltage V _M , it will be discharged, so overcharging will not occur, ensuring charging process safety. (4) During the charging process, the single battery with a higher terminal voltage is discharged while the charging process continues, and the charging speed is fast and the efficiency is high.

The implementation of the present invention will be further described below in combination with practical examples.

The lithium-ion power battery series battery pack 1 to be charged consists of 84 single cells, each with a capacity of 55Ah (Ah), the maximum charging current I _M , and the highest terminal voltage V _M of the battery is 4.15V. Both ends of each cell of the battery pack are connected to the battery voltage signal real-time acquisition and isolation amplifier circuit 2 and the discharge network 5 through wires, and the isolation amplifier circuit 2 sends the voltage signal to the main control board 3 after photoelectric isolation. The charging power source 4 is an inverter charging power source with a maximum output power of 3.5Kw and an output current of 0-10A. The positive output terminal of the charging power supply 4 is connected to the positive input terminal of the battery pack, and its negative output terminal is connected to the negative input terminal of the battery pack. The discharge network 5 is composed of 84 MOS transistors 9 and 84 power resistors 10, which are respectively connected in parallel at both ends of the battery cells.

Each output end of the isolated drive circuit 8 is connected to the control end of the MOS transistor 9, the positive pole of the single battery of the series battery pack 1 is connected to the input end of the MOS transistor 9, and the output end of the MOS transistor 9 is connected to the power resistor 10, The other end of the power resistor 10 is connected to the negative pole of the single battery of the series battery pack 1 .

The charging process is as follows: the single voltage of the battery pack to be charged is generally 3-4V, at this time the charging current is relatively large, which can be 10A, and the charging power supply 4 provides a constant DC output. During the charging process, the main control board monitors the voltage of each battery and displays it through the battery voltage display circuit 6. When it is detected that the terminal voltage of a single battery with the highest terminal voltage is close to the highest terminal voltage of 4.15V The main control board 3 drives the discharge network 5 through the isolation drive circuit 8 to discharge the single battery with a higher terminal voltage, and at the same time, continues to charge the battery with a lower terminal voltage. At this time, the charging current can be appropriately reduced. It is ensured that the terminal voltages of the batteries in the series battery pack rise synchronously, and are finally charged to the highest terminal voltage V _M at the same time, so as to realize balanced charging of the battery pack. When performing quantitative micro-discharge through the discharge network, the discharge current is determined by the power resistance of the discharge network, and the discharge time is controlled by the time relay on the main control board.

The final charging voltage set during the charging process is the highest voltage of the battery 4.15V. When the battery voltage is detected to be higher than the highest voltage of 4.15V, it will be discharged, so there will be no overcharging, ensuring the safety of the charging process .

In the charging process, in order to ensure the safety of the battery pack, a temperature sensing circuit 7 is set in each battery pack. The temperature sensing signal is input to the main control circuit board 3, and the temperature of the battery is detected in real time during the charging process. When the temperature of any battery combination exceeds the rated charging temperature, the charging power supply is turned off to suspend charging.

The isolation amplifier 2 is used to detect the voltage of each battery, which is input to the main control board 3, and the main control board drives the battery voltage inspection and display circuit 6 to display, which is convenient for observation.

The final charging result is:

The terminal voltage of each single battery is 4.15V±0.02V.

The charging process is stable and reliable, and there is no excessive temperature rise.

The present invention adopts only one set of positive and negative direct current output terminal inverter type charging power supply to directly charge the battery pack in series. Compared with the method of using multiple sets of direct current output by similar chargers, the present invention is small in size and light in weight. During the charging process, the discharge network is used to discharge the single battery with a higher terminal voltage in an appropriate amount, so that the voltage of each single battery in the battery pack rises synchronously and is sufficient at the same time to achieve automatic balance of the battery pack in series, which is safe and reliable, and improves the battery life. The battery pack is the service efficiency and life. The charging process can use a higher charging current, and the charging efficiency is high. Therefore, the present invention has good application value.

Claims (1)

1. A series battery pack automatic equalizing charging device, it comprises the series battery pack (1) to be charged, battery voltage signal real-time acquisition and isolation circuit (2), main control circuit board (3), inverter charging power supply ( 4), battery voltage inspection and display circuit (6), temperature sensor (7), isolation drive circuit (8); the battery pack connected in series is charged by an inverter charging power supply (4) with only one set of positive and negative DC output terminals, When charging, the current and voltage of the single cells of the series battery pack (1) are fed back to the real-time acquisition and isolation circuit (2) of the battery voltage signal, and the signal is input to the main control circuit board (3) through it, and at the same time the temperature of the charging battery The signal is input to the main control circuit board (3) through the temperature sensor (7), and the main control circuit board (3) inputs the signal to the battery voltage inspection and display circuit (6) and then to the charging power supply (4) and isolation The drive circuit (8) is characterized in that: each output terminal of the isolated drive circuit (8) is connected to the control terminal of the MOS tube (9), and the positive pole of the single battery of the series battery pack (1) is connected to the MOS tube (9) On the input end, the output end of the MOS tube (9) is connected to the power resistor (10), and the other end of the power resistor (10) is connected to the negative pole of the single cell of the series battery pack (1).

Images