WO2012000360A1

WO2012000360A1 - Circuit for detecting voltage of batteries

Info

Publication number: WO2012000360A1
Application number: PCT/CN2011/074783
Authority: WO
Inventors: 刘飞; 阮旭松; 林少青
Original assignee: 惠州市亿能电子有限公司
Priority date: 2010-06-28
Filing date: 2011-05-27
Publication date: 2012-01-05
Also published as: CN101865979A

Abstract

A battery voltage detecting circuit which accurately measures the voltage of each battery of a battery pack is provided. The detecting circuit comprises a main control module, and a plurality of voltage detecting modules. The voltage detecting modules are intelligent modules which are provided with MCUs. The voltage detecting modules are communicated with the main control module by means of SPI serial mode to transmit voltage data. The voltage detecting modules acquire the voltage at the two ends of each battery with a chip of an integrated operational amplifier by means of difference, and then transmit the voltage to an A/D sampling port of a single-chip. The voltage detecting modules are fundamental units in the circuit, and the quantity of batteries to be detected in the detecting modules is limited, so the problem of the output precision of the amplifier caused by the overlarge quantity of series batteries and overhigh voltage is effectively avoided. Cascading a plurality of basic modules and uploading the acquired voltage data through the communication between an SPI bus and the main control module have high expandability, thereby being capable of detecting the voltage of the series batteries with greater quantity.

Description

Multi-cell battery voltage detecting circuit

Technical field

The invention relates to the field of battery pack application, in particular to a battery voltage detecting circuit for accurately measuring voltages of individual cells in a battery pack.

Background technique

In order to achieve a certain voltage, power and energy level, the batteries need to be used in series, such as electric bicycles, energy storage systems, DC systems, and so on. Due to the inconsistency of the single cells, the battery pack may be in the charging phase, and a certain battery may be overcharged earlier than other batteries. In the discharging phase, a certain battery is over-discharged earlier than other batteries, so it is necessary The voltage of each battery in the battery pack is detected, and overcharge and overdischarge protection is performed. The existing detection circuit mostly uses the differential circuit of the operational amplifier to "differentiate" the single-cell battery voltage to the output end of the amplifier, and then uses the single-chip microcomputer with the AD function to sample the output terminal voltage to obtain the battery voltage. However, as the number of series connection of the battery increases, the voltage will become higher and higher, eventually causing the common mode voltage to affect the output of the amplifier, which reduces the accuracy of the "differential". Therefore, the battery connected in series is generally not more than six. The section is appropriate.

Summary of the invention

The problem to be solved by the present invention is to provide a battery voltage detecting circuit capable of accurately measuring the voltage of each unit cell in a large battery pack having a large number of series connected.

In order to solve the above problems, the technical solution adopted by the present invention is: a multi-cell battery voltage detecting circuit, comprising a main control module and a plurality of voltage detecting modules, wherein the voltage detecting module is an intelligent module provided with an MCU, the voltage The serial communication is used between the detection module and the main control module to transfer voltage data.

The battery voltage detecting module adopts an integrated operational amplifier chip to collect the voltage across the single battery through a differential method, and then outputs the voltage to the A/D sampling port of the single chip microcomputer.

The voltage detection module and the main control module communicate in an SPI serial manner.

The main control module is also a voltage detecting module.

The voltage detecting module has at least six voltage collecting channels, and simultaneously collects six single cell voltages.

Compared with the prior art, the invention has the beneficial effects that the solution is based on the detection module, and the number of batteries to be tested is limited in the detection module, and the output precision of the amplifier is limited due to excessive voltage of the series battery. The problem is; the plurality of basic modules are cascaded, and the collected voltage data is uploaded through the SPI bus to communicate with the main control module, and the scalability is strong, thereby realizing the measurement of the serial battery voltage with a large number.

DRAWINGS

1 is a schematic diagram of a basic unit circuit of the battery voltage detecting circuit;

2 is a circuit schematic diagram of the cascaded embodiment of the battery voltage detecting circuit.

detailed description

In order to facilitate the understanding of those skilled in the art, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

The multi-cell battery voltage detecting circuit of the invention uses the existing battery voltage detecting circuit as a detecting module and sets a main control module, and the main control module communicates with each detecting module through a serial manner. In the scheme, multiple detection modules are cascaded with the main control module by using the SPI synchronous serial bus. During operation, each detection module separately collects the voltage of each series battery in the battery pack, and then transmits the collected voltage data to the main control module through the SPI bus. Finally, the main control module summarizes the battery voltage data of each section to better realize Overcharge, over discharge protection and other functions of the battery.

Figure 1 is a schematic diagram of the circuit principle of the voltage detection module. The battery voltage detecting module adopts an integrated operational amplifier chip to collect the voltage across the single battery through a differential method, and then outputs the voltage to the A/D sampling port of the single chip microcomputer. After the microcontroller calculates the battery voltage through the sampled value, it transmits it to the main control module through the SPI bus.

In the specific implementation, the main control module can also be a voltage detection module, and the main control module itself also detects the voltage of the single battery, and undertakes the task of summing up the voltage and control. This can reduce the cost of the circuit.

2 is a circuit schematic diagram of the cascaded embodiment of the battery voltage detecting circuit. In the embodiment, n is adopted. A voltage detection module detects the battery cell voltage. The detection module where the MCU1 is located is used as the main control module, and the MCU2-MCUn is used as the slave voltage detection module.

Any data sent by the main control module can be received at the same time; only one slave detection module can send at any time, otherwise there is a conflict.

Working principle: The main control module first sends the address number of the slave detection module. The address number of the slave detection module can be written in the program in advance, or a set resistor can be added in the slave detection module to receive the slave detection of the address corresponding to itself. The module will send data to the master module.

Slave voltage detection module receiving principle: When the main control module sends a low level 0, the triode Q8 is turned on, then the branch 2 (the branch connected to the DO point of the main control module is turned on), the current size is about I=(VCC- 0.65)/R8, so the voltage at the receiving end of each slave voltage detection module is (corresponding to the respective ground): (VCC-0.65)-R7*I As long as R7(R2) is equal to R8, we get: (VCC-0.65)-R8*(VCC-0.65)/R8=0, Then, each slave voltage detecting module can receive a low level 0; when the main control module sends a high level 1, the transistor Q8 is turned off, the branch circuit 2 is not turned on, and the voltage of the receiving terminal of each slave voltage detecting module is VCC-0.65. Therefore, the slave voltage detection module receives one.

The main control module receiving principle: taking the slave voltage detection module 2 as an example, when the MCU2 sends the data 1, the triodes Q6 and Q7 are turned on, and the MCUn always outputs 1 because it is not sent, so the branch one (the DI point of the main control module) The connected branch is conductive, and the current is determined by R1 and R10. By adjusting the ratio of R1 to R10, the level required by the master module (high level) can be obtained; when MCU2 sends a low level 0. When the transistor Q6 is turned off, the branch is not turned on, the voltage on R10 is 0, and MCU2 receives 0.

The working process of branch 3 (the branch connected to the CLK point of the main control module) is the same as that of branch 2.

It should be noted that the foregoing is only a preferred embodiment of the present invention, and any minor changes and equivalent substitutions made thereto without departing from the inventive concept are all within the scope of the present invention.

Claims

A multi-cell battery voltage detecting circuit comprising a main control module and a plurality of voltage detecting modules, wherein the voltage detecting module is an intelligent module provided with an MCU, characterized in that: between the voltage detecting module and the main control module Serial communication is used to transfer voltage data.

2. The multi-cell battery voltage detecting circuit according to claim 1, wherein the battery voltage detecting module uses an integrated operational amplifier chip to acquire the voltage across the single cell through a differential method, and then outputs the signal to the single chip A/D sampling. mouth.

3. The multi-cell battery voltage detecting circuit according to claim 2, wherein the voltage detecting module and the main control module communicate by using an SPI serial bus.

4. The multi-cell battery voltage detecting circuit according to claim 3, wherein the main control module is also a voltage detecting module.

The multi-cell battery voltage detecting circuit according to claim 4, wherein the voltage detecting module has at least six voltage collecting channels and simultaneously collects six single cell voltages.