Nickel-metal hydride battery pack voltage acquisition system

Abstract

The utility model provides a nickel-metal hydride battery pack voltage acquisition system, which comprises a plurality of voltage acquisition voltage division circuits, a voltage acquisition analog front-end chip and a microcontroller, and is characterized in that the number of the voltage acquisition voltage division circuits is the same as that of battery modules connected in series in a nickel-metal hydride battery pack; one voltage acquisition voltage division circuit corresponds to one battery module in the nickel-metal hydride battery pack, and the positive electrode acquisition ends and the negative electrode acquisition ends of the plurality of voltage acquisition voltage division circuits are connected with the positive electrode ends and the negative electrode ends of the corresponding battery modules in a one-to-one correspondence manner; the positive electrode acquisition ends, the voltage division acquisition ends and the negative electrode acquisition ends of the plurality of voltage acquisition voltage division circuits are connected with corresponding voltage acquisition end points of the voltage acquisition analog front-end chip in a one-to-one correspondence manner, and the voltage acquisition analog front-end chip is connected with the microcontroller. The voltage sampling circuit is simple in structure, low in cost, high in voltage sampling speed and good in stability.

Description

Technical Field

[0001] The utility model relates to a nickel-hydrogen battery pack voltage acquisition system. Background Art

[0002] In the application of electrochemical batteries, whether nickel-metal hydride batteries or lithium batteries, the battery management system (BMS) needs to collect the battery cell or module voltage to prevent the battery from overcharging or over-discharging, which affects the battery life, capacity and other performance. If the BMS cannot quickly monitor the battery cell or module voltage at all times to manage the battery overcharging or over-discharging, the battery is very likely to fail due to thermal reasons, which may even result in safety accidents such as battery system explosion and fire. After decades of technological development, the market application scale of lithium batteries is much larger than that of nickel-metal hydride batteries. Many professional chip manufacturers have developed many professional high-precision, high-voltage sampling speed, and high-reliability voltage acquisition analog front-end (AFE) chips for the application of lithium battery BMS. However, the technology update speed of nickel-metal hydride batteries lags far behind that of lithium batteries. There are almost no dedicated AFE chips used in nickel-metal hydride battery BMS. Therefore, nickel-metal hydride battery BMS has no professional AFE chips available when collecting module voltage. Therefore, engineers need to use discrete components to design more complex voltage acquisition circuits. This makes it difficult for the designed circuit to meet BMS industry standards and relevant laws and regulations in terms of sampling speed, reliability and accuracy, making it impossible for nickel-metal hydride batteries to meet the needs of market development. Furthermore, due to the different voltage platforms of NiMH batteries and lithium batteries (NiMH battery voltage platform is 1.2V, while lithium battery voltage platform is around 3.2V or 3.6V), lithium batteries generally collect single cell voltages; the single cell voltage collected by lithium battery AFE chips is generally up to 5V, while NiMH batteries generally collect module voltages of 5 or more cells due to their lower voltage platform. Therefore, lithium battery AFE chips cannot be directly used in NiMH battery BMS. For these reasons, how to use lithium battery high-precision, high-sampling-speed, and high-reliability voltage collection AFE chips in NiMH battery BMS has become a current research topic. Utility Model Content

[0003] The utility model aims to provide a nickel-hydrogen battery pack voltage acquisition system with simple structure, low cost, fast voltage sampling speed and good stability.

[0004] The utility model is achieved through the following solutions:

[0005] A nickel-metal hydride battery pack voltage acquisition system includes several voltage acquisition and voltage-dividing circuits, a voltage acquisition analog front-end chip (AFE), and a microcontroller (MCU). The number of the voltage acquisition and voltage-dividing circuits is the same as the number of battery modules connected in series in the nickel-metal hydride battery pack. The voltage acquisition and voltage-dividing circuit includes two or more capacitors and two or more resistors. The number of the capacitors and resistors is the same. The two or more capacitors and the two or more resistors are connected in series and then connected in parallel. One end of the parallel capacitors and resistors serves as a positive electrode acquisition terminal, and the other end of the parallel capacitors and resistors serves as a negative electrode acquisition terminal. Two adjacent resistors are connected to two adjacent capacitors and then led out as a voltage-dividing acquisition terminal. One voltage acquisition and voltage-dividing circuit corresponds to one battery module in the nickel-metal hydride battery pack. The positive electrode acquisition terminals and negative electrode acquisition terminals of the several voltage acquisition and voltage-dividing circuits are connected one-to-one with the positive terminal and negative terminal of the corresponding battery module. The positive electrode acquisition terminals, voltage-dividing acquisition terminals, and negative electrode acquisition terminals of the several voltage acquisition and voltage-dividing circuits are connected one-to-one with the corresponding voltage acquisition terminals of the voltage acquisition analog front-end chip. The voltage acquisition analog front-end chip is connected to the microcontroller. The voltage acquisition analog front-end chip and the microcontroller are typically connected via communication. The number of resistors and capacitors in the voltage acquisition divider circuit is determined based on the corresponding battery module's voltage upper limit and the single-cell acquisition voltage range of the voltage acquisition analog front-end chip (AFE). Generally, if there are two resistors and capacitors, the voltage acquisition divider circuit can achieve a two-way voltage divider. If there are three resistors and capacitors, the voltage acquisition divider circuit can achieve a three-way voltage divider, and so on. The single-cell acquisition voltage range of the voltage acquisition analog front-end chip (AFE) is generally 0-5V. If the battery module's voltage upper limit is between 5V and 10V (excluding 5V), a two-way voltage acquisition divider circuit is used. If the battery module's voltage is between 10V and 15V (excluding 10V), a three-way voltage acquisition divider circuit is used, and so on. To ensure that the voltage values ​​collected by each voltage acquisition endpoint in the voltage acquisition analog front-end chip are similar, the resistors and capacitors in the voltage acquisition divider circuit are selected with consistent parameters. The voltage acquisition divider circuit, the voltage acquisition analog front-end chip, and the microcontroller (MCU) are all located within the battery management system (BMS).

[0006] Furthermore, the voltage acquisition voltage divider circuit also includes a component that performs an opening and closing function, and the component that performs an opening and closing function is provided with a weak current control circuit and a load circuit. The positive end of the weak current control circuit of the component that performs an opening and closing function is communicatively connected to the IO port of the microcontroller, and the negative end of the weak current control circuit of the component that performs an opening and closing function is grounded. The weak current control circuit of the component that performs an opening and closing function is used to receive a control signal issued by the microcontroller. The load circuit of the component that performs an opening and closing function is connected in series to the positive electrode acquisition end, that is, the negative end of the load circuit of the component that performs an opening and closing function is connected to the positive electrode acquisition end, and the positive end of the load circuit of the component that performs an opening and closing function is respectively connected to the positive end of the corresponding battery module and the corresponding voltage acquisition end point of the voltage acquisition analog front-end chip.

[0007] Furthermore, the component having the function of switching is a photo MOS tube, a relay or an electronic switch.

[0008] Furthermore, the positive electrode sampling terminals and negative electrode sampling terminals of two adjacent voltage collection and voltage divider circuits overlap with the connection lines of the corresponding battery modules and voltage collection analog front-end chips.

[0009] The utility model provides a nickel-metal hydride battery pack voltage acquisition system with a simple structure. Through the voltage acquisition voltage divider circuit, it can simply and quickly use the voltage acquisition analog front-end chip for lithium batteries on the market with high voltage accuracy, high voltage sampling speed and high reliability. It can greatly simplify the design difficulty, reduce the cost and development cost of the battery management system BMS for nickel-metal hydride batteries, improve the stability of the battery management system BMS, and timely and accurately monitor the voltage of the battery module, providing a guarantee for extending the battery life and improving the safety and reliability of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a schematic diagram of the structure of the nickel-metal hydride battery pack voltage acquisition system in Example 1. DETAILED DESCRIPTION

[0011] The embodiments are only intended to illustrate one implementation of the present invention and are not intended to limit the scope of protection of the present invention.

[0012] Example 1

[0013] A nickel-metal hydride battery pack voltage acquisition system, such as Figure 1As shown, it includes several voltage acquisition and voltage divider circuits 1, a voltage acquisition analog front-end chip AFE 2 and a microcontroller MCU 3. The number of voltage acquisition and voltage divider circuits 1 is the same as the number of battery modules L connected in series in the nickel-metal hydride battery pack. The battery module L in this embodiment 1 is composed of five single nickel-metal hydride batteries connected in series. The upper limit of its fully charged voltage is 8V. The single-cell acquisition voltage range of the voltage acquisition analog front-end chip is 0-5V. Therefore, this embodiment 1 adopts a two-voltage voltage acquisition and voltage divider circuit. The voltage acquisition and voltage divider circuit 1 includes two capacitors (C1, C2), two resistors (R1, R2) and a component 4 with a switching function. The parameters of the two resistors are consistent. The parameters of the two capacitors are consistent. The component 4 with a switching function is provided with a weak current control circuit 41 and a load circuit 42. The component with a switching function in this embodiment 1 is a photo MOS tube. The two capacitors (C1, C2) and the two resistors (R1, R2) are connected in series and then in parallel. One end of the parallel capacitor and resistor serves as the positive electrode acquisition terminal C + The other end of the capacitor and resistor connected in parallel is used as the negative electrode collection terminal C － , the two adjacent resistors and the two adjacent capacitors are connected correspondingly and then led out as the voltage dividing terminal C 分 The positive end of the weak current control circuit 41 of the switching component 4 is connected to the IO port of the microcontroller 3, the negative end of the weak current control circuit 41 of the switching component 4 is grounded, and the load circuit 42 of the switching component 4 is connected in series to the positive electrode collection terminal C + The negative end of the load circuit 42 of the component 4 that plays the role of opening and closing is connected to the positive electrode collection terminal C + connected, a voltage acquisition voltage divider circuit 1 corresponds to a battery module L in the nickel-hydrogen battery pack, and the positive end and negative electrode acquisition end C of the load circuit 42 of the switching component 4 of the voltage acquisition voltage divider circuit 1 － Connected to the positive and negative terminals of the corresponding battery modules L, the positive terminals of the load circuit 42 of the switching component 4 of the voltage acquisition and voltage divider circuit 1, and the voltage acquisition terminals C 分 , negative electrode collection terminal C － They are connected one-to-one with the corresponding voltage acquisition endpoints of the voltage acquisition analog front-end chip 2. The relative positive acquisition terminals and negative sampling terminals of the two adjacent voltage acquisition divider circuits 1 overlap with the connection lines of the corresponding battery module L and the voltage acquisition analog front-end chip 2. The voltage acquisition analog front-end chip 2 is communicatively connected with the microcontroller 3.

[0014] The battery modules are numbered L1, L2, L3...Ln respectively. The voltage acquisition endpoints of the voltage acquisition analog front-end chip corresponding to the negative sampling terminal of the voltage acquisition divider circuit, the voltage acquisition terminal, and the positive terminal of the load circuit of the component with a switching function of the battery module L1 are numbered CB0, CB1, and CB2 respectively. The voltage acquisition endpoints of the voltage acquisition analog front-end chip corresponding to the negative sampling terminal of the voltage acquisition divider circuit, the voltage acquisition terminal, and the positive terminal of the load circuit of the component with a switching function of the battery module L2 are numbered CB2, CB3, and CB4 respectively. Similarly, the voltage acquisition endpoints of the voltage acquisition analog front-end chip corresponding to the negative sampling terminal of the voltage acquisition divider circuit, the voltage acquisition terminal, and the positive terminal of the load circuit of the component with a switching function of the battery module Ln are numbered CB2n-2, CB2n-1, and CB2n respectively.

[0015] When it is necessary to collect the voltage of a certain battery module, multiple battery modules or the entire battery pack, the microcontroller MCU sends a control signal to the weak current control circuit of the corresponding switching component as needed. The corresponding switching component is turned on after receiving the signal, and the corresponding voltage collection divider circuit is activated. At this time, the corresponding voltage collection endpoints of the voltage collection analog front-end chip start to collect data and transmit the collected data to the microcontroller MCU. The voltage of battery module L1 is the sum of the voltages collected by the voltage collection endpoints CB1 and CB2, the voltage of battery module L2 is the sum of the voltages collected by the collection endpoints CB3 and CB4, and so on. The voltage of battery module Ln is the sum of the voltages collected by the collection endpoints CB2n-1 and CB2n. The voltage of the entire battery pack is the sum of the voltages of battery modules L1, L2, L3...Ln.

[0016] Example 2

[0017] A nickel-metal hydride battery pack voltage acquisition system has a structure similar to that of the nickel-metal hydride battery pack voltage acquisition system in Example 1, except that the battery module in Example 2 is composed of seven nickel-metal hydride battery cells connected in series, the upper limit of their fully charged voltage is 11.2V, and the single-cell acquisition voltage range of the voltage acquisition analog front-end chip is 0-5V. Therefore, Example 2 uses a three-voltage voltage acquisition divider circuit. The number of resistors and capacitors in the voltage acquisition divider circuit is three, and the component that performs the switching function is a relay.

[0018] The battery modules are numbered L1, L2, L3...Ln respectively. The voltage acquisition endpoints of the voltage acquisition analog front-end chip corresponding to the negative sampling terminal of the voltage acquisition divider circuit, the voltage acquisition terminal, and the positive terminal of the load circuit of the component with a switching function of the battery module L1 are numbered CB0, CB1, CB2, and CB3 respectively. The voltage acquisition endpoints of the voltage acquisition analog front-end chip corresponding to the negative sampling terminal of the voltage acquisition divider circuit, the voltage acquisition terminal, and the positive terminal of the load circuit of the component with a switching function of the battery module L2 are numbered CB3, CB4, CB5, and CB6 respectively. Similarly, the voltage acquisition endpoints of the voltage acquisition analog front-end chip corresponding to the negative sampling terminal of the voltage acquisition divider circuit, the voltage acquisition terminal, and the positive terminal of the load circuit of the component with a switching function of the battery module Ln are numbered CB3n-3, CB3n-2, CB3n-1, and CB3n respectively.

[0019] The activation method of the voltage acquisition divider circuit in this embodiment 2 is the same as the activation method of the voltage acquisition divider circuit in embodiment 1. The corresponding voltage acquisition endpoints of the voltage acquisition analog front-end chip start to collect data and transmit the collected data to the microcontroller MCU. The voltage of the battery module L1 is the sum of the voltages collected by the voltage acquisition endpoints CB1, CB2 and CB3. The voltage of the battery module L2 is the sum of the voltages collected by the acquisition endpoints CB4, CB5 and CB6. Similarly, the voltage of the battery module Ln is the sum of the voltages collected by the acquisition endpoints CB3n-2, CB3n-1 and CB3n. The voltage of the entire battery pack is the sum of the voltages of the battery modules L1, L2, L3...Ln.

[0020] Example 3

[0021] A nickel-metal hydride battery pack voltage acquisition system has a structure similar to that of the nickel-metal hydride battery pack voltage acquisition system in Example 1, except that the battery module in Example 3 is composed of twelve nickel-metal hydride battery cells connected in series, the upper limit of the fully charged voltage is 19.2V, and the single cell acquisition voltage range of the voltage acquisition analog front-end chip is 0-5V. Therefore, Example 3 uses a four-voltage voltage acquisition divider circuit. The number of resistors and capacitors in the voltage acquisition divider circuit is four, and the component that performs the opening and closing function is an electronic switch.

[0022] The battery modules are numbered L1, L2, L3...Ln respectively. The voltage acquisition endpoints of the voltage acquisition analog front-end chip corresponding to the negative sampling terminal of the voltage acquisition divider circuit, the voltage acquisition terminal, and the positive terminal of the load circuit of the component with a switching function of the battery module L1 are numbered CB0, CB1, CB2, CB3, and CB4 respectively. The voltage acquisition endpoints of the voltage acquisition analog front-end chip corresponding to the negative sampling terminal of the voltage acquisition divider circuit, the voltage acquisition terminal, and the positive terminal of the load circuit of the component with a switching function of the battery module L2 are numbered CB4, CB5, CB6, CB7, and CB8 respectively. Similarly, the voltage acquisition endpoints of the voltage acquisition analog front-end chip corresponding to the negative sampling terminal of the voltage acquisition divider circuit, the voltage acquisition terminal, and the positive terminal of the load circuit of the component with a switching function of the battery module Ln are numbered CB4n-4, CB4n-3, CB4n-2, CB4n-1, and CB4n respectively.

[0023] The activation method of the voltage acquisition divider circuit in this embodiment 3 is the same as the activation method of the voltage acquisition divider circuit in embodiment 1. The corresponding voltage acquisition endpoints of the voltage acquisition analog front-end chip start to collect data and transmit the collected data to the microcontroller MCU. The voltage of the battery module L1 is the sum of the voltages collected by the voltage acquisition endpoints CB1, CB2, CB3 and CB4. The voltage of the battery module L2 is the sum of the voltages collected by the acquisition endpoints CB5, CB6, CB7 and CB8. Similarly, the voltage of the battery module Ln is the sum of the voltages collected by the acquisition endpoints CB4n-3, CB4n-2, CB4n-1 and CB4n. The voltage of the entire battery pack is the sum of the voltages of the battery modules L1, L2, L3...Ln.

Claims

1. A nickel-metal hydride battery pack voltage acquisition system, characterized by: The invention comprises a plurality of voltage acquisition and voltage divider circuits, a voltage acquisition analog front-end chip and a microcontroller. The number of the voltage acquisition and voltage divider circuits is the same as the number of battery modules connected in series in the nickel-hydrogen battery pack. The voltage acquisition and voltage divider circuit comprises two or more capacitors and two or more resistors. The number of the capacitors and resistors is the same. The two or more capacitors and the two or more resistors are connected in series and then connected in parallel. One end of the parallel capacitors and resistors serves as a positive electrode acquisition end, and the other end of the parallel capacitors and resistors serves as a negative electrode acquisition end. Two adjacent resistors are connected to two adjacent capacitors and then lead out as a voltage acquisition end. One voltage acquisition and voltage divider circuit corresponds to one battery module in the nickel-hydrogen battery pack. The positive electrode acquisition end and the negative electrode acquisition end of the plurality of voltage acquisition and voltage divider circuits are connected one-to-one with the positive end and the negative end of the corresponding battery module. The positive electrode acquisition end, the voltage acquisition end and the negative electrode acquisition end of the plurality of voltage acquisition and voltage divider circuits are connected one-to-one with the corresponding voltage acquisition end points of the voltage acquisition analog front-end chip. The voltage acquisition analog front-end chip is connected to the microcontroller.

2. The nickel-metal hydride battery pack voltage acquisition system according to claim 1, characterized in that: The voltage acquisition and voltage divider circuit also includes a component that performs an opening and closing function. The component that performs an opening and closing function is provided with a weak current control circuit and a load circuit. The positive end of the weak current control circuit of the component that performs an opening and closing function is communicatively connected to the microcontroller, the negative end of the weak current control circuit of the component that performs an opening and closing function is grounded, and the load circuit of the component that performs an opening and closing function is connected in series to the positive electrode acquisition terminal.

3. The nickel-metal hydride battery pack voltage acquisition system according to claim 2, characterized in that: The component having the function of opening and closing is a photo MOS tube, a relay or an electronic switch.

4. A nickel-metal hydride battery pack voltage acquisition system according to any one of claims 1 to 3, characterized in that: The positive electrode sampling terminals and negative electrode sampling terminals of two adjacent voltage collection and voltage dividing circuits overlap with the connection lines of the corresponding battery modules and voltage collection analog front-end chips.

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