Control and protection circuit for single-lithium battery electric tool and detection and control method for control and protection circuit

Abstract

The invention discloses a control and protection circuit for a single-lithium battery electric tool and a detection and control method for the control and protection circuit. The control and protection circuit comprises a singlechip power supply circuit, a battery charging and discharging voltage detection circuit, a battery charging and discharging temperature detection circuit, a battery charging control management circuit, a motor switching and commutation control circuit and a working state indication circuit. A singlechip is used as a master control integrated circuit (IC), and is matched with simple peripheral components to realize all functions of protecting and controlling the single-lithium battery electric tool, so that the functions are flexibly designed, circuit complexity is lowered, the number of electronic components is decreased, cost is lowered, and the circuit is high in safety and reliability, and is almost power consumption-free when not working, and has the advantages of environment friendliness, energy saving, lightweight, convenience for use, high operation efficiency, long cycle life of a battery, and the like.

Description

technical field [0001] The invention relates to a lithium battery electric tool, in particular to a control and protection circuit of the lithium battery electric tool and a detection and control method thereof. Background technique [0002] The use of DC power tools directly replaces hand tools, reduces the labor intensity of people's work, and improves work efficiency. Especially the DC power tools that use power lithium-ion batteries reduce the weight of power tools and improve The cycle life of the battery meets the needs of environmental protection and is loved by people. [0003] Due to its own characteristics, the power lithium-ion battery has strict requirements on the battery voltage, discharge current and temperature during the charging and discharging process. cause safety accidents such as fire or explosion. Since electric tools using a single-cell (nominal voltage 3.6V) power lithium-ion battery are usually small in size, the battery is fixed and installed in ...

AI Technical Summary

Problems solved by technology

Since the general single-cell protection IC is designed for mobile phone digital products, the charging and discharging current is small during operation, the discharge load is basically a resistive load, the discharge is stable, and there is no need for temperature protection function, while the load of a single-cell lithium battery DC power tool is DC brushed motor has the characteristics of large discharge current, rapid temperature rise during battery operation, large electric spark interference when the motor is running, and particularly high back EMF of the motor, so ICs for mobile phone digitals are used as single-cell lithium-ion DC power tools. The protection scheme has incomplete protection functions, such as no temperature protection function and multi-stage current protection function, the parameters of charge and discharge protection voltage and discharge protection current are fixed by the IC manufacturer and cannot be changed, and various working and protection states of electric tools cannot be displayed etc., unfriendly user interface, relatively low security and reliability, etc.

[0005] Therefore, ICs used in mobile digital products are not suitable for the protection and control of lithium battery electric tools. The circuit will become more complicated, the number of components will increase greatly, and there is basically no installation space in the power tool, so the practical value is not great

[0006] The circuit principle of ordinary single-cell lithium battery protection IC is as follows: figure 1 As shown, although the structure is simple, the protection function is not comprehensive when used in lithium electric power tools, and the safety and reliability are low.

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