Automatic switching lithium battery circuit capable of charging in parallel and discharging in series

Abstract

The invention provides an automatic switching lithium battery circuit capable of charging in parallel and discharging in series, n lithium batteries B1-Bn are connected in series and then are connected with a load, and a switch Si is connected between every two lithium batteries; the charging power supply DC is connected in parallel with n charging protection circuits; each charging protection circuit is connected in parallel with a lithium battery; when the lithium batteries are charged in an equalizing manner, all the switches Si are switched off, the lithium batteries are connected in parallel, the charging power supply DC charges the lithium batteries through the charging protection circuit, and the lithium batteries are switched off from a charging loop through the charging protection circuit when being fully charged; when the lithium batteries supply power to the load, all the switches Si are closed, and the lithium batteries are connected in series to supply power to the load. By using the method, the defects that an existing active method relates to a complicated circuit and is long in equalization time, a resistor in a passive method can cause energy waste and increase battery heat, the method cannot be applied to long-term reliable operation of the lithium battery, and the control is simple can be overcome.

Description

Technical Field

[0001] The invention belongs to the technical field of reliability, and in particular relates to an automatic switching lithium battery circuit for parallel charging and series discharging. Background Art

[0002] A lithium battery pack is composed of multiple single lithium batteries connected in series. Due to the differences between the single batteries, the terminal voltage rises inconsistently during series charging, resulting in some single batteries being overcharged and some being undercharged. The ideal state is that each battery process rises synchronously and is completely consistent, and charging stops when it is close to full charge. Usually, the battery balancing method is used to achieve voltage consistency of the series lithium battery single batteries.

[0003] At present, in engineering applications, lithium battery equalization methods usually adopt active methods and passive methods. The active method achieves single-cell voltage consistency by adding switches and energy storage devices, and the passive method achieves voltage consistency by adding resistance to achieve high consumption. Among the above equalization methods, the active method involves complex circuits and long equalization time, and the resistance in the passive method will cause energy waste and increase battery heat. It cannot be applied to lithium batteries for long-term reliable operation and simple control. Summary of the invention

[0004] In view of this, the present invention provides an automatic switching lithium battery circuit for parallel charging and series discharging to solve the shortcomings of the existing active method involving complex circuits and long balancing time, the passive method using resistors that wastes energy and increases battery heat, and cannot be applied to long-term reliable operation of lithium batteries, and the control is simple.

[0005] In order to solve the above technical problems, the present invention is implemented as follows.

[0006] A parallel charging and series discharging automatic switching lithium battery circuit, comprising:

[0007] n lithium batteries B1~Bn are connected in series and then connected to the load, and a switch Si is connected between every two lithium batteries, i=1~n-1;

[0008] The charging power source DC is connected in parallel with n charging protection circuits; each charging protection circuit is connected in parallel with a lithium battery;

[0009] When the lithium battery is balanced charged, all switches Si are disconnected, the lithium batteries are all connected in parallel, and the charging power supply DC charges the lithium battery through the charging protection circuit. When the lithium battery is full, it is disconnected from the charging circuit through the charging protection circuit.

[0010] When the lithium battery supplies power to the load, all switches Si are closed, and the lithium batteries form a series connection to supply power to the load.

[0011] Preferably, the charging protection circuit includes a linear voltage regulator diode W1, a configuration resistor circuit, a MOS tube T1, and a diode D;

[0012] The positive pole of the charging power supply DC is connected to the positive pole of the lithium battery through the positively connected diode D, and the negative pole of the lithium battery is connected to the negative pole of the charging power supply DC after being connected to the MOS tube T1; when the MOS tube T1 is controlled to be turned on, the charging power supply DC charges the lithium battery;

[0013] The positive electrode of the charging power supply DC is further connected to the linear voltage regulator diode W1 connected in reverse series, and then connected to the negative electrode of the charging power supply DC; the negative electrode of the voltage regulator diode W1 is connected to the gate of the MOS tube T1, and the conduction and clamping of the MOS tube T1 are controlled according to whether the linear voltage regulator diode W1 is turned on;

[0014] The control end of the linear voltage regulator diode W1 is coupled to the voltage divider end of the configuration resistor circuit; by configuring the resistance value of the configuration resistor circuit, the linear voltage regulator diode W1 is turned on when the lithium battery reaches the full voltage, the MOS tube T1 is clamped, and the lithium battery charging channel is closed.

[0015] Preferably, the configuration resistor circuit includes a second resistor and a third resistor;

[0016] The resistor R2 is connected between the positive electrode of the charging power supply DC and the control end of the linear voltage regulator diode W1;

[0017] The resistor R3 is connected between the control end of the linear voltage stabilizing diode W1 and the negative electrode of the charging power supply DC;

[0018] The resistance values ​​of the second resistor and the third resistor are configured so that DC×(resistance value of the third resistor) / (the sum of the resistance values ​​of the second resistor and the third resistor) is equal to the full charge voltage of the lithium battery.

[0019] Preferably, a resistor R1 is further connected between the positive electrode of the charging power source DC and the linear voltage regulator diode W1.

[0020] Beneficial effects:

[0021] (1) The present invention provides a parallel charging and series discharging automatic switching lithium battery circuit, and proposes a new solution. Through the automatic switching of parallel charging and series discharging, the active method involves complex circuits and long balancing time, and the resistance in the passive method will cause energy waste and increase battery heat, and cannot be applied to lithium batteries in long-term reliable operation and simple control occasions. This technical solution can achieve the consistency of each single cell voltage during parallel charging, reduce the charging voltage level, and use a series structure to achieve high voltage output when supplying power to the load, and has good engineering applicability.

[0022] (2) In a preferred embodiment, a method is proposed to realize the full charge power-off function by using the coordination of a configuration resistor circuit, a linear voltage regulator diode and a MOS tube, which can realize automatic full charge identification.

[0023] (3) In a preferred embodiment, the configuration resistor circuit is implemented using a voltage divider resistor. The circuit is simple, and the capacitor is used as a voltage divider. It will not increase the heat of the battery, and can be used in situations where lithium batteries need to operate reliably for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The schematic diagram of the automatic switching lithium battery circuit for parallel charging and series discharging of the present invention.

[0025] Figure 2 1 is a circuit diagram of a charging protection circuit in Embodiment 1 of the present invention (dashed frame portion). DETAILED DESCRIPTION

[0026] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0027] The present invention provides an automatic switching lithium battery circuit for parallel charging and series discharging. The method adopts all parallel connection when charging the lithium battery evenly, and automatically disconnects from the charging circuit through the charging protection circuit when the battery is full; and adopts all series connection when supplying power to the load. The above method can achieve the consistency of each collective voltage during parallel charging, and reduce the charging voltage level. When supplying power to the load, a series structure is used to achieve high-voltage output, and it has good engineering applicability.

[0028] Figure 1 The schematic diagram of the automatic switching lithium battery circuit of parallel charging and series discharging of the present invention is shown. Figure 1 As shown, n lithium batteries B1 to Bn are connected in series and then connected to a load, and a switch Si is connected between every two lithium batteries, i=1 to n-1, and each switch controls whether the lithium batteries are connected in series.

[0029] N charging protection circuits are connected in parallel between the positive and negative poles of the charging power source DC, and the charging protection circuits are also connected in parallel. The two output ends of each charging protection circuit are connected to the two poles of a lithium battery.

[0030] When the lithium battery is balanced charged, all switches Si are disconnected, the lithium batteries are all connected in parallel, and the charging power supply DC charges the lithium battery through the charging protection circuit. When the lithium battery is full, it is disconnected from the charging circuit through the charging protection circuit.

[0031] When the lithium battery supplies power to the load, all switches Si are closed and the lithium batteries are connected in series.

[0032] Figure 2FIG. 2 shows a circuit diagram of a charging protection circuit in a preferred embodiment of the present invention. Figure 2 As shown, the charging protection circuit includes a linear voltage regulator diode W1, a configuration resistor circuit, a MOS tube T1, and a diode D.

[0033] The positive pole of the charging power supply DC is connected to the positive pole of the lithium battery through the positively connected diode D, and the negative pole of the lithium battery is connected to the negative pole of the charging power supply DC after being connected to the MOS tube T1; when the MOS tube T1 is controlled to be turned on, the charging power supply DC charges the lithium battery;

[0034] The positive electrode of the charging power supply DC is further connected to the linear voltage regulator diode W1 connected in reverse series, and then connected to the negative electrode of the charging power supply DC; the negative electrode of the voltage regulator diode W1 is connected to the gate of the MOS tube T1, and the conduction and clamping of the MOS tube T1 are controlled according to whether the linear voltage regulator diode W1 is turned on;

[0035] The control end of the linear voltage regulator diode W1 is coupled to the voltage divider end of the configuration resistor circuit; by configuring the resistance value of the configuration resistor circuit, the linear voltage regulator diode W1 is turned on when the lithium battery reaches the full voltage, the MOS tube T1 is clamped, and the lithium battery charging channel is closed.

[0036] In this embodiment, the resistor circuit includes resistor R2, resistor R3, and resistor R4; resistor R3 and resistor R4 can be implemented by one resistor, and using two resistors is conducive to the accurate configuration of the resistance value. Resistor R2 is connected between the positive pole of the charging power supply DC and the control end of the linear voltage regulator diode W1; resistor R3 and resistor R4 are connected in series between the control end of the linear voltage regulator diode W1 and the negative pole of the charging power supply DC; by configuring the resistors, DC×(R3+R4) / (R3+R4+R2) is equal to the full charge voltage of the lithium battery.

[0037] In this embodiment, a resistor R1 is further connected between the positive electrode of the charging power source DC and the linear voltage regulator diode W1.

[0038] The present invention provides an automatic switching lithium battery circuit for parallel charging and series discharging, and the working process is as follows:

[0039] 1) In charging mode, switches S1~S(n-1) are disconnected, and lithium batteries B1-Bn form a parallel structure and are charged in parallel through charging protection circuit 1~charging protection circuit n; after full charging, charging protection circuit 1~charging protection circuit n are automatically disconnected; in power supply mode, S1~S(n-1) are closed, and all batteries are connected in series to supply power to the load.

[0040] The charging protection circuit includes a diode D, resistors R1-R4, a MOS tube T1, and a linear voltage regulator W1; the automatic full charge disconnection principle of the charging protection circuit is as follows: in this case, Vcc=DC=5V, and according to the full charge voltage of different lithium battery cells, the resistors are configured so that 5×(R3+R4) / (R3+R4+R2) is equal to the full charge voltage; when the lithium battery cell B is charged, since the lithium battery B has not reached the full charge voltage, the linear voltage regulator W1 is disconnected, and Vcc supplies power to the gate of the MOS tube T1 through the current limiting resistor R1, and the MOS tube T1 is turned on, and Vcc charges the lithium battery B through the diode D1 and the MOS tube T1; when the lithium battery B reaches the full charge voltage, the linear voltage regulator W1 is turned on, the gate of the MOS tube T1 is clamped by the linear voltage regulator W1, the MOS tube T1 is disconnected, and the lithium battery B is disconnected from the charging circuit and stops charging.

[0041] The above specific embodiments only describe the design principle of the present invention. The shapes and names of the components in the description may be different and are not limited. Therefore, those skilled in the art in the field of the present invention may modify or replace the technical solutions recorded in the above embodiments; and these modifications and replacements do not deviate from the creative purpose and technical solutions of the present invention and should all fall within the protection scope of the present invention.

Claims

1. A parallel charging and series discharging automatic switching lithium battery circuit, characterized in that: include: n lithium batteries B1~Bn are connected in series and then connected to the load, and a switch Si is connected between every two lithium batteries, i=1~n-1; The charging power source DC is connected in parallel with n charging protection circuits; each charging protection circuit is connected in parallel with a lithium battery; When the lithium battery is balanced charged, all switches Si are disconnected, the lithium batteries are all connected in parallel, and the charging power supply DC charges the lithium battery through the charging protection circuit. When the lithium battery is full, it is disconnected from the charging circuit through the charging protection circuit. When the lithium battery supplies power to the load, all switches Si are closed, and the lithium batteries form a series connection to supply power to the load.

2. The automatic switching lithium battery circuit for parallel charging and series discharging as claimed in claim 1, characterized in that: The charging protection circuit includes a linear voltage regulator diode W1, a configuration resistor circuit, a MOS tube T1, and a diode D; The positive pole of the charging power supply DC is connected to the positive pole of the lithium battery through the positively connected diode D, and the negative pole of the lithium battery is connected to the negative pole of the charging power supply DC after being connected to the MOS tube T1; when the MOS tube T1 is controlled to be turned on, the charging power supply DC charges the lithium battery; The positive electrode of the charging power supply DC is further connected to the linear voltage regulator diode W1 connected in reverse series, and then connected to the negative electrode of the charging power supply DC; the negative electrode of the voltage regulator diode W1 is connected to the gate of the MOS tube T1, and the conduction and clamping of the MOS tube T1 are controlled according to whether the linear voltage regulator diode W1 is turned on; The control end of the linear voltage regulator diode W1 is coupled to the voltage divider end of the configuration resistor circuit; by configuring the resistance value of the configuration resistor circuit, the linear voltage regulator diode W1 is turned on when the lithium battery reaches the full voltage, the MOS tube T1 is clamped, and the lithium battery charging channel is closed.

3. The automatic switching lithium battery circuit for parallel charging and series discharging as claimed in claim 2, characterized in that: The resistor circuit includes a second resistor and a third resistor; The resistor R2 is connected between the positive electrode of the charging power supply DC and the control end of the linear voltage regulator diode W1; The resistor R3 is connected between the control end of the linear voltage stabilizing diode W1 and the negative electrode of the charging power supply DC; The resistance values ​​of the second resistor and the third resistor are configured so that DC×(resistance value of the third resistor) / (the sum of the resistance values ​​of the second resistor and the third resistor) is equal to the full charge voltage of the lithium battery.

4. The automatic switching lithium battery circuit for parallel charging and series discharging as claimed in claim 2, characterized in that: A resistor R1 is further connected between the positive electrode of the charging power source DC and the linear voltage regulator diode W1.

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