Series battery pack power supply circuit

Abstract

The utility model relates to the technical field of MCU power supply of electric tools, in particular to a series battery pack power supply circuit, which comprises two battery packs connected in series and a three-phase full-bridge circuit, and the two battery packs are electrically connected with the three-phase full-bridge circuit respectively. A midpoint power supply position BatCV is arranged between the two battery packs, and the output end of the midpoint power supply position BatCV is connected with a voltage reduction module; a power interface is arranged between one battery pack and the three-phase full-bridge circuit, and a main loop breaking switch is arranged between SW + and SW-of the power interface; according to the utility model, the midpoint power supply position BatCV is ingeniously utilized to supply power to the MCU, and the midpoint power supply position BatCV can be connected with the voltage reduction module to realize voltage reduction and also has a voltage stabilization function, so that the application effect of the circuit is improved; a main loop switch is arranged, so that the safety problem under the control failure condition can be effectively cut off; the device is reasonable in overall design, simple in structure, low in manufacturing cost and suitable for market popularization and application.

Description

Technical Field

[0001] The utility model relates to the technical field of MCU power supply for electric tools, in particular to a series-connected battery pack power supply circuit. Background Art

[0002] Electric machines such as power tools are increasingly driven by rechargeable battery packs such as lithium-ion batteries. The lithium battery pack also powers the MCU of the power tool. To improve the portability of the power tool, the MCU load current used is very small. To avoid burning out the MCU, the power supply from the lithium battery pack needs to be stepped down first.

[0003] In traditional technology, a BUCK circuit is used to step down the power supply of a lithium battery pack. The electronic components included in the BUCK circuit include MOSFET field effect transistors, power diodes, inductors, input capacitors, output capacitors, etc. The use of multiple electronic components makes the circuit material cost high, which is not conducive to large-scale promotion and use in the market. Utility Model Content

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a series battery pack power supply circuit to solve the problem of high material cost in the prior art method of using a BUCK circuit to reduce the voltage of the power supply of a lithium battery pack.

[0005] To achieve the above-mentioned and other related purposes, the utility model provides a series battery pack power supply circuit, comprising two battery packs connected in series and a three-phase full-bridge circuit, wherein the two battery packs are electrically connected to the three-phase full-bridge circuit respectively;

[0006] A midpoint power supply position BatCV is provided between the two battery packs, and a step-down module is connected to the output end of the midpoint power supply position BatCV;

[0007] The step-down module is composed of a current limiting resistor R3, a transistor Q1, and a voltage stabilizing chip U1. One end of the current limiting resistor R3 is connected to the midpoint power supply position BatCV, and the other end is connected to the emitter of the transistor Q1. The collector of the transistor Q1 is connected to the voltage stabilizing chip U1 to power the MCU after voltage stabilization.

[0008] A second transistor Q2 is connected to the base of the transistor Q1, a third resistor R3 is connected to the base of the second transistor Q2, and the emitter of the second transistor Q2 and the other end of the third resistor R3 are both grounded;

[0009] A power interface is provided between one of the battery packs and the three-phase full-bridge circuit, and a main circuit disconnecting switch is provided between SW+ and SW- of the power interface.

[0010] In an embodiment of the present invention, the voltage-reducing module further includes a second voltage-stabilizing chip U2 , and the second voltage-stabilizing chip U2 is connected in series to the voltage-stabilizing chip U1 .

[0011] In one embodiment of the present invention, the voltage stabilizing chip U1 and the second voltage stabilizing chip U2 are both linear voltage stabilizing chips.

[0012] In an embodiment of the present invention, the transistor Q1 is a PNP transistor, the second transistor Q2 is an NPN transistor, and the base of the transistor Q1 is connected to the collector of the second transistor Q2.

[0013] In an embodiment of the present invention, a second resistor R7 is connected between the emitter and the base of the transistor Q1 .

[0014] In one embodiment of the utility model, the three-phase full-bridge circuit includes an upper arm and a lower arm, and the upper arm and the lower arm have the same structure, both including a U phase, a V phase and a W phase, and each phase uses two MOS switches, and the S pole of the MOS switch located in the upper arm of the same phase is connected to the D pole of the MOS switch located in the lower arm.

[0015] As described above, the series battery pack power supply circuit of the utility model has the following beneficial effects:

[0016] 1. By using BatCV, the midpoint power supply position between the two battery packs connected in series, and combining with the buck module to step down the supply voltage, the MCU is powered. Compared with the conventional buck circuit, the utility model uses fewer electronic components to achieve the same buck function, has a simple structure, and saves unnecessary circuit material costs. In addition, the buck module uses a dual voltage regulator chip to effectively improve the stability of the supply voltage.

[0017] 2. By setting the main circuit disconnect switch, when the MCU of this circuit fails, the power supply circuit can be effectively cut off by the main circuit disconnect switch, thereby improving the safety of circuit use;

[0018] 3. The utility model cleverly uses the midpoint power supply position BatCV to power the MCU. Through the midpoint power supply position BatCV, the step-down module can be connected to realize voltage reduction while also having a voltage stabilization function, thereby improving the application effect of the circuit; the setting of the main circuit cut-off switch can effectively cut off safety issues in the event of control failure; the overall circuit design is reasonable, the structure is simple, the number of electronic components used is reduced, the circuit cost is effectively reduced, and it is suitable for market promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Shown is a block diagram of the series battery pack power supply circuit disclosed in the present utility model.

[0020] Figure 2 Shown is a partial circuit schematic diagram of the series battery pack power supply circuit disclosed in the present utility model.

[0021] Figure 3 Shown is another partial circuit schematic diagram of the series battery pack power supply circuit disclosed in the present utility model.

[0022] Component number description

[0023] Battery pack 1; three-phase full-bridge circuit 2; step-down module 3; power interface 4; main circuit disconnect switch 5. DETAILED DESCRIPTION

[0024] The following is a description of the implementation of the present invention by means of specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0025] See also Figures 1 to 3 It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings in this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions under which the utility model can be implemented. Therefore, they have no substantial technical significance. Any structural modification, change in proportion or adjustment of size should still fall within the scope of the technical content disclosed by the utility model without affecting the effects and purposes that can be achieved by the utility model.

[0026] See also Figure 1-2 The utility model provides a series battery pack power supply circuit, including two battery packs 1 connected in series and a three-phase full-bridge circuit 2, the two battery packs 1 are electrically connected to the three-phase full-bridge circuit 2 respectively; the three-phase full-bridge circuit 2 includes an upper arm and a lower arm, the upper arm and the lower arm have the same structure, both include a U phase, a V phase and a W phase, each phase uses two MOS switches, and the S pole of the MOS switch located in the upper arm of the same phase is connected to the D pole of the MOS switch located in the lower arm.

[0027] See also Figure 2-3A midpoint power supply position BatCV is provided between the two battery packs 1, and a step-down module 3 is connected to the output end of the midpoint power supply position BatCV; the step-down module 3 is composed of a current limiting resistor R3, a transistor Q1, and a voltage stabilizing chip U1, and the transistor Q1 is a PNP transistor; one end of the current limiting resistor R3 is connected to the midpoint power supply position BatCV, and the other end is connected to the emitter of the transistor Q1, and the collector of the transistor Q1 is connected to the voltage stabilizing chip U1 to power the MCU after voltage stabilization; a second transistor Q2 is connected to the base of the transistor Q1, and a third resistor R3 is connected to the base of the second transistor Q2, and the emitter of the second transistor Q2 and the other end of the third resistor R3 are both grounded; the second transistor Q2 is an NPN transistor, and specifically, the base of the transistor Q1 is connected to the collector of the second transistor Q2.

[0028] The step-down module 3 also includes a second voltage stabilizing chip U2, which is connected in series to the voltage stabilizing chip U1. The dual voltage stabilizing chips can work together to provide a more stable voltage output and enhance the stability and reliability of the circuit; the current limiting resistor R1 limits the current to reduce the input voltage, and a low voltage is output after the voltage is stepped down by the transistor Q1 and stabilized by the voltage stabilizing chip U1 and the second voltage stabilizing chip U2.

[0029] The utility model powers the MCU by stepping down the supply voltage at BatCV, the midpoint power supply position between the two battery packs 1 connected in series, in cooperation with the step-down module 3. Compared with the conventional technology of stepping down the voltage by using a BUCK circuit, the utility model uses fewer electronic components to achieve the same step-down function, has a simple structure, and saves unnecessary circuit material costs.

[0030] The voltage stabilizing chip U1 and the second voltage stabilizing chip U2 are both linear voltage stabilizing chips, which have the advantages of fast response speed, good stability, low cost, stable output voltage, small ripple, good load regulation rate and linear regulation rate, and wide application range.

[0031] A second resistor R7 is connected between the emitter and base of the transistor Q1; since the transistor Q1 and the second transistor Q2 still have leakage current in the off state, especially when the temperature is very high, the leakage current will also rise sharply, which may cause a large leakage current to flow through the be junction of the transistor Q1 and cause the transistor Q1 to be accidentally turned on. The second resistor R7 can provide a path for the actual leakage current, preventing a large leakage current from flowing through the be junction of the transistor Q1 and causing the transistor Q1 to be turned on accidentally.

[0032] A power interface 4 is provided between one of the battery packs 1 and the three-phase full-bridge circuit 2, and a main circuit disconnecting switch 5 is provided between SW+ and SW- of the power interface. In the event of failure of the MCU of the circuit, the power supply circuit can be effectively disconnected by the main circuit disconnecting switch 5, thereby improving the safety of circuit use.

[0033] In summary, the utility model cleverly uses the midpoint power supply position BatCV to power the MCU, and can connect the step-down module 3 through the midpoint power supply position BatCV to achieve step-down while also having a voltage stabilization function, thereby improving the application effect of the circuit; the setting of the main circuit switch 5 can effectively cut off the safety problem in the case of control failure; the overall circuit design is reasonable, the structure is simple, the number of electronic components used is reduced, the circuit cost is effectively reduced, and it is suitable for market promotion and application. Therefore, the utility model effectively overcomes the various shortcomings of the prior art and has a high industrial utilization value.

[0034] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed in the present invention shall still be covered by the claims of the present invention.

Claims

1. A series battery pack power supply circuit, comprising two battery packs connected in series and a three-phase full-bridge circuit, wherein the two battery packs are electrically connected to the three-phase full-bridge circuit respectively; Features: A midpoint power supply position BatCV is provided between the two battery packs, and a step-down module is connected to the output end of the midpoint power supply position BatCV; The step-down module is composed of a current limiting resistor R3, a transistor Q1, and a voltage stabilizing chip U1. One end of the current limiting resistor R3 is connected to the midpoint power supply position BatCV, and the other end is connected to the emitter of the transistor Q1. The collector of the transistor Q1 is connected to the voltage stabilizing chip U1 to power the MCU after voltage stabilization. A second transistor Q2 is connected to the base of the transistor Q1, a third resistor R3 is connected to the base of the second transistor Q2, and the emitter of the second transistor Q2 and the other end of the third resistor R3 are both grounded; A power interface is provided between one of the battery packs and the three-phase full-bridge circuit, and a main circuit disconnecting switch is provided between SW+ and SW- of the power interface.

2. The series battery pack power supply circuit according to claim 1, characterized in that: The voltage-reducing module further includes a second voltage-stabilizing chip U2 , which is connected in series to the voltage-stabilizing chip U1 .

3. The series battery pack power supply circuit according to claim 2, characterized in that: The voltage stabilizing chip U1 and the second voltage stabilizing chip U2 are both linear voltage stabilizing chips.

4. The series battery pack power supply circuit according to claim 1, characterized in that: The transistor Q1 is a PNP transistor, the second transistor Q2 is an NPN transistor, and the base of the transistor Q1 is connected to the collector of the second transistor Q2.

5. The series battery pack power supply circuit according to claim 4, characterized in that: A second resistor R7 is connected between the emitter and the base of the transistor Q1.

6. The series battery pack power supply circuit according to claim 1, characterized in that: The three-phase full-bridge circuit includes an upper arm and a lower arm. The upper arm and the lower arm have the same structure and both include a U phase, a V phase and a W phase. Each phase uses two MOS switches. The S pole of the MOS switch located in the upper arm of the same phase is connected to the D pole of the MOS switch located in the lower arm.

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