Parallel charging and discharging equalization method for lithium battery plate and implementation circuit thereof

Abstract

The application discloses a kind of lithium battery panel parallel charging and discharging equalization implementation circuit, it is suitable for equipping the lithium battery panel of boost-buck charging circuit, automatic power-off after charging is completed, battery capacity equalization and so on, including parallel current limiting module, microcontroller, parallel switch module, output protection module.Parallel current limiting module input end connects lithium battery panel output end, output end connects output protection module input end.Microcontroller input end connects parallel current limiting module output end, lithium battery panel output end, parallel switch module charging port, output end connects parallel switch module control end.Parallel switch module input end connects parallel current limiting module output end, control end connects microcontroller output end, output end connects lithium battery panel charging end.Output protection module input end connects parallel current limiting module output end, output end connects load.Circuit is integrated on a piece of printed circuit board, provides the interface connected with lithium battery panel, need not change the topology of original lithium battery panel, it is convenient to use.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power management and control, in particular to a parallel charging and discharging equalization method and its implementation circuit for a lithium battery panel product equipped with a boost-buck charging circuit, overcurrent protection, overvoltage protection, automatic power-off upon completion of charging, battery capacity equalization, and MPPT function. BACKGROUND

[0002] Mobile power sources have a wide range of applications in civilian fields. In addition to industrial equipment, robots, computer servers, and other applications that require high reliability, a large part of the application scenarios are leisure scenarios such as outdoor travel. For the above applications, there are mature lithium battery panel products on the market that integrate charging and discharging, overcurrent, overvoltage, and overtemperature protection functions into one. When more than one battery is configured on the lithium battery panel, an equalization circuit is needed to balance the capacity between the multiple batteries during discharging and charging to avoid damage.

[0003] In the market, up to 5 lithium batteries can be configured on a single lithium battery panel, and too many batteries will affect the size and portability. When the required power or voltage exceeds the upper limit of a single lithium battery panel when outdoors, parallel discharging between lithium battery panels becomes particularly critical. Currently, there are no lithium battery panel products on the market that can be randomly connected in parallel to double the power of the same model.

[0004] During the use of parallel lithium battery panels, there may be a problem of voltage difference between the panels. If they are directly connected in parallel for discharging, the lithium battery panel with a lower voltage may have an excessively large current, which may pose a risk of burning.

[0005] Therefore, in order to ensure sufficient power and safe parallel connection, it is necessary to provide a parallel discharging equalization method and its implementation circuit for a lithium battery panel. SUMMARY

[0006] In view of the above problems, the present application provides a parallel charging and discharging equalization method and its implementation circuit for a lithium battery panel.

[0007] The application discloses a kind of lithium battery panel parallel charging and discharging equalization implementation circuit, it is suitable for the lithium battery panel of being equipped with boost-buck charging circuit, overcurrent protection, overvoltage protection, charging completion automatic power-off, battery power balance and MPPT function, it includes parallel current limiting module, microcontroller, parallel switch module, output protection module, charging module.The input end of the parallel current limiting module is connected the output end of each lithium battery panel, and the input end of the output protection module is connected.The input end of the microcontroller is connected the output end of the parallel current limiting module for parallel voltage detection, and the output end of each lithium battery panel is also connected for the voltage detection of each lithium battery panel, and the charging port of the parallel switch module is also connected for power supply detection, and the output end is connected the control end of the parallel switch module.The input end of the parallel switch module is connected the output end of the parallel current limiting module, and the output end is connected the charging end of each lithium battery panel.The input end of the output protection module is connected the output end of the parallel current limiting module, and the output end is the output of entire circuit, and is connected load.

[0008] The parallel current limiting module is used to limit the current of each lithium battery panel connected in parallel, and N input ends are respectively connected to the output ends of N lithium battery panels connected in parallel.The parallel current limiting module includes a current limiting circuit and an ideal diode circuit.N input ends are respectively connected to a current limiting circuit and an ideal diode circuit in sequence, the current limiting circuit is used to limit the output current of each lithium battery panel connected in parallel, to prevent excessive current caused by uneven output power due to different voltages of N lithium battery panels connected in parallel, and the ideal diode circuit is used to ensure the one-way nature of power supply of N lithium battery panels connected in parallel, to prevent voltage backflow caused by parallel voltage exceeding the voltage of lithium battery panels connected in parallel.N output ends of the ideal diode circuit are connected together to form a parallel voltage, which is output from the output end.

[0009] The parallel switch module is used to open or shut off the energy transfer channel of the lithium battery panel according to the control signal of the microcontroller, so as to realize the energy balance between the panels.The parallel switch module includes a parallel switch driver and a parallel switch circuit.The input end of the parallel switch driver is connected to the output end of the microcontroller, and the output end is connected to the control end of the parallel switch circuit.The input end of the parallel switch circuit is connected to the output end of the parallel current limiting circuit, and the output end of the parallel switch circuit is the output of the parallel switch module, which is connected to the charging end of N lithium battery panels.The parallel switch module further includes a charging port, which is the external power supply end of the entire circuit, and is connected to an external power supply.The charging port is connected to each output in parallel through N diodes inside the parallel switch module.

[0010] The microcontroller is used for voltage detection, state judgment and control signal generation. The input end of the microcontroller is connected with the output end of the parallel current limiting module, the output end of the N lithium battery panels and the charging port of the parallel switch module. The input end of the microcontroller is connected with the output end of the parallel current limiting module and the output end of the N lithium battery panels, the parallel voltage and the voltage of the N lithium battery panels are detected respectively, the parallel voltage and the voltage of the N lithium battery panels are compared, if the output signal of the parallel current limiting module is greater than the voltage of the corresponding lithium battery panel, the microcontroller sends a conduction signal to the corresponding switch driver in the parallel switch module, and the parallel switch circuit is turned on; if the output signal of the parallel current limiting module is less than the voltage of the corresponding lithium battery panel, the microcontroller does not send a conduction signal to the corresponding switch driver in the parallel switch module, and the parallel switch circuit is turned off. The input end of the microcontroller is also connected with the charging port of the parallel switch module, if there is an external power supply, the microcontroller does not send a conduction signal to all switch drivers in the parallel switch module, and all parallel switch circuits are turned off, and the N lithium battery panels are charged by the external power supply.

[0011] The output protection module comprises an overcurrent protection circuit.

[0012] Based on the above-mentioned parallel charging and discharging equalization circuit of the lithium battery panel, the application further provides a parallel charging and discharging equalization method of the lithium battery panel which is equipped with a buck-boost charging circuit, overcurrent protection, overvoltage protection, automatic power-off after charging completion, battery capacity equalization and MPPT function. The method comprises the following steps:

[0013] S1. The microcontroller detects the connection of the charging port of the parallel switch module, and judges whether there is an external power supply; if there is an external power supply, the microcontroller does not send a conduction signal to all switch drivers in the parallel switch module, all parallel switch circuits are turned off, and the N lithium battery panels are charged by the external power supply without equalization; if there is no external power supply, S2 is performed.

[0014] S2. The microcontroller detects and obtains the voltage of each parallel lithium battery panel and the voltage after parallel connection (i.e. the output voltage of the parallel current limiting module).

[0015] S3. The microcontroller compares the voltage of each parallel lithium battery panel with the voltage after parallel connection respectively.

[0016] S3.1. When the voltage of a certain lithium battery panel is higher than the voltage after parallel connection, the microcontroller does not send a conduction signal to the switch driver corresponding to the lithium battery panel in the parallel switch module, and the corresponding parallel switch circuit is turned off.

[0017] S3.2-When the voltage of a certain lithium battery panel is lower than the voltage after parallel connection, the microcontroller sends a driving signal to the switch driver corresponding to the lithium battery panel in the parallel switch module, and turns on the corresponding parallel switch circuit;

[0018] S4-Repeat S3 until the voltage of all lithium battery panels is consistent with the voltage after parallel connection, and the microcontroller no longer acts.

[0019] The parallel charging and discharging circuit and the parallel charging and discharging equalization method of the lithium battery panel of the present application are suitable for lithium battery panels equipped with a boost-buck charging circuit, overcurrent protection, overvoltage protection, automatic power-off after charging is completed, battery capacity equalization, and MPPT function. Due to the unidirectional conductivity of the ideal diode circuit in the parallel current limiting module, after parallel connection, the lithium battery panel with the highest voltage will first discharge, at the same time, supply power to the load and charge the lithium battery panel with a voltage lower than the parallel voltage; with the charging and discharging of lithium battery panels with different voltages, the lithium battery panels reaching the parallel voltage begin to discharge one by one through the ideal diode circuit, at this time, the power provided by the parallel lithium battery panels increases. The discharge curve of the lithium battery shows that when it is in the initial zone and the falling zone, the voltage drops rapidly, even if there is a pressure difference between the lithium battery panels, there will be no safety problems caused by a large amount of heat, so the lithium battery panels can be directly connected in parallel for discharging. Due to the existence of the parallel current limiting circuit, even if the discharge equalization is not completed, the lithium battery panels can still be used normally after parallel connection, but the maximum power cannot be output; after the parallel connection of the lithium battery panels is completed, the output can reach the maximum power. The implementation circuit of the present application is integrated on a printed circuit board, provides an interface connected with each lithium battery panel connected in parallel, does not need to change the topology of the original lithium battery panel, and is convenient to carry and use.

[0020] In order to make the above content of the present application more obvious and easy to understand, the following preferred embodiments are specifically described below, and the accompanying drawings are described in detail as follows. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments, and it should be understood that the following drawings only show some embodiments of the present application, and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0022] Figure 1 A schematic block diagram of the parallel charging and discharging circuit of the lithium battery panel of the present application;

[0023] Figure 2 A boost-buck charging circuit topology schematic diagram of the lithium battery panel suitable for the present application;

[0024] Figure 3 A flow chart of a parallel charging and discharging equalization method according to the present application;

[0025] Numbering in the figure:

[0026] 10: parallel current limiting module; 20: microcontroller;

[0027] 30: parallel switch module; 40: output protection module. DETAILED DESCRIPTION

[0028] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application.

[0029] Please refer to Figure 1 A schematic block diagram of an implementation circuit of parallel charging and discharging of lithium battery plates according to the present application, including a parallel current limiting module 10, a microcontroller 20, a parallel switch module 30, and an output protection module 40. The input end of the parallel current limiting module 10 is connected to the output end of each lithium battery plate, and the output end is connected to the input end of the output protection module 40. The input end of the microcontroller 20 is connected to the output end of the parallel current limiting module 10, and is also connected to the output end of each lithium battery plate, and is also connected to the charging port of the parallel switch module 30, and the output is connected to the control end of the parallel switch module 30. The input end of the parallel switch module 30 is connected to the output end of the parallel current limiting module 10, the control end is connected to the output end of the microcontroller 20, and the output end is connected to the charging end of each lithium battery plate. The input end of the output protection module 40 is connected to the output end of the parallel current limiting module 10, and the output end is the output of the entire circuit, connected to the load.

[0030] Please refer to Figure 2 A topology schematic diagram of a boost-buck charging circuit for lithium battery plates to which the present application is applicable, and the present application can only be applied in lithium battery plates using the charging circuit. If it is a common charging circuit, the charging voltage is close to the battery voltage, and the charging cannot be completed; by using the boost-buck charging circuit, the voltage after parallel connection through the circuit according to the present application can be increased, thereby completing the energy transfer.

[0031] Please refer to Figure 3A flow chart of a parallel charging and discharging equalization method according to the present application. First is step S1: the microcontroller detects the connection of the charging port of the parallel switch module and determines whether an external power source is connected; if yes, the microcontroller does not act and the equalization ends; if not, step S2 is performed. Next is step S2: the microcontroller detects and obtains the voltage of each parallel connected lithium battery panel and the voltage after parallel connection (i.e. the output voltage of the parallel current limiting module). Then is step S3: the microcontroller compares the voltage of each parallel connected lithium battery panel with the voltage after parallel connection; when the voltage of a certain lithium battery panel is higher than the voltage after parallel connection, step S3.1 is performed: the microcontroller does not send a conduction signal to the switch driver corresponding to the lithium battery panel in the parallel switch module, and the corresponding parallel switch circuit is turned off; when the voltage of a certain lithium battery panel is lower than the voltage after parallel connection, step S3.2 is performed: the microcontroller sends a conduction signal to the switch driver corresponding to the lithium battery panel in the parallel switch module, and the corresponding parallel switch circuit is turned on. Finally is step S4: step S3 is repeated until the voltage of all lithium battery panels is consistent with the voltage after parallel connection, and the microcontroller does not act. At this point, the equalization is completed.

[0032] The above description is only an embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent flow transformation using the content of the present application specification and drawings, or direct or indirect application in other related technical fields, is also included in the patent protection scope of the present application.

Claims

1. A circuit for realizing parallel charging and discharging equalization of lithium battery panels, characterized in that, The parallel current limiting module, the microcontroller, the parallel switch module and the output protection module are included; the input end of the parallel current limiting module is connected with the output end of each lithium battery panel, and the output end is connected with the input end of the output protection module; the input end of the microcontroller is connected with the output end of the parallel current limiting module for parallel voltage detection, and is also connected with the output end of each lithium battery panel for voltage detection of each lithium battery panel, and is also connected with the charging port of the parallel switch module for power supply detection, and the output end is connected with the control end of the parallel switch module; the input end of the parallel switch module is connected with the output end of the parallel current limiting module, the control end is connected with the output end of the microcontroller, and the output end is connected with the charging end of each lithium battery panel; the input end of the output protection module is connected with the output end of the parallel current limiting module, and the output end is the output of the whole circuit and is connected with the load; the output protection module is an overcurrent protection circuit. The microcontroller is used for voltage detection, state judgment and control signal generation; the input end of the microcontroller is connected with the output end of the parallel current limiting module, and is also connected with the output end of N lithium battery panels and the charging port of the parallel switch module; the input end of the microcontroller is connected with the output end of the parallel current limiting module and the output end of N lithium battery panels, parallel voltage and the voltage of N lithium battery panels are detected respectively, the parallel voltage and the voltage of N lithium battery panels are compared, if the output signal of the parallel current limiting module is greater than the voltage of the corresponding lithium battery panel, a conduction signal is sent to the corresponding switch driver in the parallel switch module to turn on the parallel switch circuit; if the output signal of the parallel current limiting module is less than the voltage of the corresponding lithium battery panel, no conduction signal is sent to the corresponding switch driver in the parallel switch module to turn off the parallel switch circuit; the input end of the microcontroller is also connected with the charging port of the parallel switch module, if there is an external power supply, no conduction signal is sent to all switch drivers in the parallel switch module to turn off all parallel switch circuits, and the N lithium battery panels are charged by the external power supply.

2. The implementation circuit of parallel charging and discharging equalization of lithium battery plates according to claim 1, characterized in that, The parallel current limiting module is used for limiting the current of each parallel lithium battery panel, and N input ends are respectively connected with the output ends of N parallel lithium battery panels; the parallel current limiting module includes a current limiting circuit and an ideal diode circuit; N input ends are respectively connected with one current limiting circuit and one ideal diode circuit in sequence, the outputs of N ideal diode circuits are connected together to form a parallel voltage, and the parallel voltage is output from the output end.

3. The implementation circuit of parallel charging and discharging equalization of lithium battery plates according to claim 1, characterized in that, The parallel switch module is used to open or shut off the energy transfer channel of the lithium battery panel according to the control signal of the microcontroller; the parallel switch module comprises a parallel switch driver and a parallel switch circuit; the input end of the parallel switch driver is connected with the output end of the microcontroller, and the output end is connected with the control end of the parallel switch circuit; the input end of the parallel switch circuit is connected with the output end of the parallel current limiting circuit, and the output end of the parallel switch circuit is the output of the parallel switch module, and is connected with the charging end of the N lithium battery panels; the parallel switch module further comprises a charging port, which is the external power supply end of the entire circuit, and is connected with an external power supply; the charging port is connected with each output in parallel through N diodes in the parallel switch module.

4. A parallel charging and discharging equalization method for a lithium battery plate using the parallel charging and discharging equalization implementation circuit of the lithium battery plate of claim 1, characterized in that, The method comprises the following steps: S1-the microcontroller detects the connection of the charging port of the parallel switch module, judges whether there is an external power supply connected, if there is an external power supply connected, the microcontroller does not send a drive signal to all switch drivers in the parallel switch module, disconnects all parallel switch circuits, and charges N lithium battery panels by the external power supply without balancing; if there is no external power supply connected, S2 is performed; S2-the microcontroller detects and obtains the voltage of each lithium battery panel connected in parallel and the voltage after parallel connection (i.e. the output voltage of the parallel current limiting module); S3-the microcontroller compares the voltage of each lithium battery panel connected in parallel with the voltage after parallel connection respectively; S3.1-when the voltage of a certain lithium battery panel is higher than the voltage after parallel connection, the microcontroller does not send a drive signal to the switch driver corresponding to the lithium battery panel in the parallel switch module, and disconnects the corresponding parallel switch circuit; S3.2-when the voltage of a certain lithium battery panel is lower than the voltage after parallel connection, the microcontroller sends a drive signal to the switch driver corresponding to the lithium battery panel in the parallel switch module, and turns on the corresponding parallel switch circuit; S4-repeating S3 until the voltage of all lithium battery panels is consistent with the voltage after parallel connection, and the microcontroller does not act any more.

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