High-side opening control circuit in lithium battery management system

Abstract

The utility model discloses a circuit with a high-side split port control function. The circuit is composed of an analog front-end chip acquisition control circuit, a high-side split power NMOS tube control circuit and a single-chip microcomputer logic control circuit, and the high-side split power NMOS tube control circuit comprises an analog front-end chip control signal, a high-side power NMOS tube, a divider resistor, a TVS protection device, a Zener diode and a PMOS control device; an analog front-end control signal is connected with a high-side power NMOS (N-channel Metal Oxide Semiconductor) tube, an analog front-end chip sends out high-side driving signals AFECHG and AFEDIS to drive the high-side power NMOS tube, and the high-side power NMOS tube is controlled to be connected and disconnected through a voltage division circuit, a voltage stabilizing diode, a PMOS (P-channel Metal Oxide Semiconductor) control device and a TVS (Transient Voltage Suppressor) protection device in sequence. According to the utility model, the lithium battery management system interrupts the independent control of the charge-discharge loop of the positive pole input and output of the battery pack.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium battery management systems, and particularly to a circuit for high-side split-port power control of a lithium battery management system. Background Art

[0002] With the wide application of lithium batteries in life, we have higher requirements for the safe use of lithium battery packs. The high-side control scheme in the lithium battery management system completely controls the positive electrode of the entire battery pack, which is safer than the traditional method of disconnecting the negative electrode circuit of the battery pack. It independently controls the charging and discharging of the lithium battery management system, and better realizes the charging and discharging management of the battery pack.

[0003] The design of the high-side split-port control circuit in the lithium battery management system is generally applicable to small lithium battery management systems, usually referring to lithium battery management systems with 16 series connections and a total voltage not exceeding 60V. The battery packs using this management system are mostly found in mobile robots for autonomous navigation, electric two-wheel vehicles, electric tricycles, service robots, etc. The characteristics of this lithium battery management system are that it uses self-power supply of the battery pack, has no auxiliary power supply, has an external power-on switch, and has a function of communicating with the host.

[0004] In the lithium battery management system, a common power NMOS transistor is used to control the charging and discharging circuit, which is generally applied to low-side protection, that is, the method of disconnecting the negative electrode of the battery pack, resulting in the total positive of the battery pack being directly led to the external interface through the power plug-in. In this low-side control method, in some cases, the external interface is prone to accidental contact, causing safety accidents in the use of the lithium battery pack. The high-side split-port control circuit avoids the direct connection of the positive electrode of the battery pack to the external power plug-in by disconnecting the positive electrode of the battery pack, realizes independent control of the charging circuit and the discharging circuit, and logically can achieve the control function that the charging port is not powered during discharging and the discharging port is not powered during charging, better manages the safe path of the lithium battery pack, and effectively protects the safe use of the lithium battery pack. Summary of the Utility Model

[0005] The utility model provides a design scheme of a high-side split-port power NMOS control circuit to protect the safe use of lithium battery packs.

[0006] To achieve the above object, the present utility model is realized through the following technical solutions. A high-side split-port control circuit is composed of an analog front-end chip acquisition control circuit, a high-side split-port power NMOS transistor control circuit, and a single-chip microcomputer logic control circuit. The high-side split-port power NMOS transistor control circuit includes an analog front-end chip control signal, a high-side power NMOS transistor, a voltage-dividing resistor, a TVS protection device, a voltage-stabilizing diode, and a PMOS control device. The analog front-end control signal is connected to the high-side power NMOS transistor. The analog front-end chip issues high-side drive signals AFE_CHG and AFE_DIS to drive the high-side power NMOS transistor, which successively passes through a voltage-dividing circuit, a voltage-stabilizing diode, a PMOS control device, and a TVS protection device to control the conduction and disconnection of the high-side power NMOS transistor, thereby realizing independent control of the charge and discharge circuits for interrupting the positive input and output of the battery pack in the lithium battery management system.

[0007] The analog front-end chip acquisition control circuit includes an analog front-end chip, a power supply circuit, resistors, capacitors, and a filtering circuit, which are used for detecting the single-cell voltage, temperature, charge and discharge current of the lithium battery pack, and outputting drive signals for the high-side power NMOS transistor. The analog front-end chip transmits the collected data to the single-chip microcomputer through internal communication, which is used as the basis for the single-chip microcomputer logic control to make judgments.

[0008] The single-chip microcomputer logic control circuit makes logical judgments based on the data transmitted by the analog front-end chip. After the data self-check is successful, the single-chip microcomputer issues a signal to close the charge and discharge circuit through internal communication, which is executed by the analog front-end chip to issue drive signals.

[0009] Compared with the prior art, the present utility model has the following beneficial effects:

[0010] The high-side split-port control circuit of the present utility model can completely cut off the connection between the positive electrode of the lithium battery and the output positive electrode. When the lithium battery pack is powered off, the connectors are not charged, effectively preventing safety accidents caused by accidental contact with external power plugs. In addition, according to the actual project requirements, independent control of the charge and discharge paths can be realized, and the logic control is relatively flexible. It can control the charging port to be uncharged during discharge and the discharge port to be uncharged during charging, better managing the safety path of the lithium battery pack and effectively protecting the safe use of the lithium battery pack.

[0011] The present utility model adopts an analog front-end chip high-side NMOS drive, a power NMOS transistor, a voltage-dividing resistor, a TVS protection device, a voltage-stabilizing diode, and a PMOS control device to control the conduction and disconnection of the high-side power NMOS transistor, realizing independent control of the charge and discharge circuits for interrupting the positive input and output of the battery pack in the lithium battery management system, better managing the safety path of the lithium battery pack, and effectively protecting the safe use of the lithium battery pack. Description of the Drawings

[0012] Figure 1 It is the acquisition control circuit diagram of the analog front-end chip;

[0013] Figure 2 It is the control circuit diagram of the high-side split-port power NMOS transistor;

[0014] Figure 3 It is the topology diagram of the lithium battery management system. Specific implementation manners

[0015] The following details the specific implementation manners provided according to the present utility model in combination with preferred implementation cases.

[0016] A high-side split-port control circuit in a lithium battery management system of the present utility model is composed of an analog front-end chip acquisition control circuit, a high-side split-port power NMOS transistor control circuit, and a single-chip microcomputer logic control circuit. The high-side split-port power NMOS transistor control circuit includes an analog front-end chip control signal, a high-side power NMOS transistor, a voltage-dividing resistor, a TVS protection device, a voltage-stabilizing diode, and a PMOS control device. The analog front-end control signal is connected to the high-side power NMOS transistor, and the high-side drive signals AFE_CHG and AFE_DIS are sent out by the analog front-end chip to drive the high-side power NMOS transistor, which successively passes through a voltage-dividing circuit, a voltage-stabilizing diode, a PMOS control device, and a TVS protection device to control the conduction and disconnection of the high-side power NMOS transistor, so as to realize the independent control of the charge and discharge circuits for the input and output of the positive electrode of the battery pack in the lithium battery management system. It can better manage the safety path of the lithium battery pack and effectively protect the use safety of the lithium battery pack.

[0017] The working principle and process of the present utility model are as follows:

[0018] The high-side split-port control circuit of the lithium battery management system is mainly composed of an analog front-end chip acquisition control circuit, a high-side split-port power NMOS transistor control circuit, and a single-chip microcomputer logic control circuit (these three circuits are existing technologies respectively, and in this solution, they are interconnected according to actual needs to realize signal transmission and change the control method). For details, see Figure 3 , the parts within the dashed boxes in the figure are each part of the circuit. The three parts of the circuit are interconnected and signal transmission is carried out to realize the high-side split-port control function. The high-side split-port control circuit is a part of the charge and discharge circuit control in the lithium battery management system. Its working principle and process are as follows: Figure 1It is an acquisition control circuit for the analog front-end chip, mainly composed of an analog front-end chip (hereinafter referred to as AFE), a power supply circuit, and filtering circuits such as resistors and capacitors, and is used for detecting the single-cell voltage, temperature, charge and discharge current of the lithium battery pack, as well as outputting the drive signal of the NMOS transistor. In addition, the AFE transmits the collected data to the single-chip microcomputer through internal communication, which is used as the basis for the logical control of the single-chip microcomputer. After the lithium battery management system is powered on and running, the acquisition control circuit of the analog front-end chip U1 starts to work. After the collected information is correct, the built-in charge pump circuit of the chip raises the drive voltage to a value higher than the total voltage of the lithium battery by 10V. This voltage sends out the drive signals AFE_CHG and AFE_DIS through the pins Pin23 and Pin28 of the U1 chip (see Figure 2 , and the drive signals are connected to the power NMOS transistors). Figure 2 The high-side split-port power NMOS transistor control circuit is mainly composed of a power NMOS transistor, a voltage-dividing circuit, a voltage-stabilizing diode, a TVS protection device, etc., and is used for controlling the charge and discharge loop, playing the role of a switch. The single-chip microcomputer control circuit makes logical judgments based on the data transmitted by the AFE. After the data self-check is successful, the single-chip microcomputer sends out a signal to close the charge and discharge loop through internal communication, which is executed by the AFE chip and sends out a drive signal. The drive signal protects the gate-source voltage through the voltage-dividing resistor one R3, the voltage-dividing resistor two R7, the voltage-dividing resistor three R10, the voltage-stabilizing diode one D1, the voltage-stabilizing diode two D7, and the voltage-stabilizing diode three D8. The PMOS control device Q3 protects against the overflow of the drive voltage, drives the power NMOS transistor, controls the discharge NMOS transistor one Q1, the discharge NMOS transistor two Q2, the charging NMOS transistor one Q4, the charging NMOS transistor two Q5, the charging NMOS transistor three Q6, and the charging NMOS transistor four Q7 to conduct, and the battery pack starts to charge and discharge, realizing the high-side split-port control of the lithium battery pack, reasonably managing the power path, and more effectively protecting the use safety of the lithium battery pack.

Claims

1. A high-side branch control circuit in a lithium battery management system, characterized in that: It consists of an analog front-end chip acquisition control circuit, a high-side split-port power NMOS transistor control circuit, and a single-chip microcomputer logic control circuit. The high-side split-port power NMOS transistor control circuit includes an analog front-end chip control signal, a high-side power NMOS transistor, a voltage-dividing resistor, a TVS protection device, a voltage-regulating diode, and a PMOS control device. The analog front-end control signal is connected to the high-side power NMOS transistor, and the high-side drive signals AFE_CHG and AFE_DIS are sent by the analog front-end chip to drive the high-side power NMOS transistor, which successively passes through a voltage-dividing circuit, a voltage-regulating diode, a PMOS control device, and a TVS protection device to control the on and off of the high-side power NMOS transistor, realizing the independent control of the charge and discharge loop for interrupting the positive input and output of the battery pack in the lithium battery management system.

2. The high-side branch control circuit in the lithium battery management system according to claim 1, wherein: The analog front-end chip acquisition control circuit includes an analog front-end chip, a power supply circuit, resistors, capacitors, and a filtering circuit, which is used for detecting the single-cell voltage, temperature, charge and discharge current of the lithium battery pack, and outputting the drive signal for the high-side power NMOS transistor. The analog front-end chip transmits the collected data to the single-chip microcomputer through internal communication, which is used as the basis for the single-chip microcomputer logic control judgment.

3. The high-side branch control circuit in the lithium battery management system according to claim 1, wherein: The single-chip microcomputer logic control circuit makes a logical judgment based on the data transmitted by the analog front-end chip. After the data self-check is successful, the single-chip microcomputer sends a signal to close the charge and discharge loop through internal communication, which is executed by the analog front-end chip to send a drive signal.

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