Self-balancing battery charging circuit and charging method

Abstract

The present invention proposes a self-balancing battery charging circuit and charging method, which are used to charge N batteries connected in series, the negative electrode of the Nth battery is connected to the positive electrode of the N-1th battery, N>1, and the charging circuit includes a voltage stabilizing circuit and a charge pump circuit, the voltage stabilizing circuit receives an input voltage, and its output end is connected to the input end of the charge pump circuit, the output end of the charge pump circuit is connected to N batteries connected in series, and the first battery is connected in parallel to the output end of the voltage stabilizing circuit; the voltage of each battery is equal to the output voltage of the voltage stabilizing circuit. The present invention can achieve automatic balancing after the battery is fully charged.

Description

Technical Field

[0001] The present invention relates to the field of power electronics, and in particular to a self-balancing battery charging circuit and a charging method. Background Art

[0002] Batteries are not absolutely consistent. After forming a group, if the capacity difference between batteries exceeds a certain threshold, it will affect the actual available capacity of the entire battery pack. Therefore, the life of the battery after forming a group is much lower than the life of a single battery. The main reason is the individual differences between batteries, which leads to the battery with the largest capacity being easily overcharged during charging, and the battery with the smallest capacity being easily over-discharged during discharging, entering a vicious cycle, causing individual batteries to be damaged, affecting the charge and discharge characteristics of the entire battery pack, and reducing the capacity of the battery pack. In order to extend the service life of the battery pack, it is necessary to balance the different batteries. Summary of the invention

[0003] The purpose of the present invention is to provide a self-balancing battery charging circuit and a charging method which can automatically balance the battery after it is fully charged, so as to solve the technical problem of battery voltage imbalance in the prior art.

[0004] To achieve the above-mentioned purpose, the present invention provides a self-balancing battery charging circuit, which is used to charge N batteries connected in series, wherein the negative electrode of the Nth battery is connected to the positive electrode of the N-1th battery, and N>1, and comprises: a voltage stabilizing circuit and a charge pump circuit, wherein the voltage stabilizing circuit receives an input voltage, and its output end is connected to the input end of the charge pump circuit, and the output end of the charge pump circuit is connected to the N batteries connected in series, and the first battery is connected in parallel to the output end of the voltage stabilizing circuit; and the voltage of each battery is equal to the output voltage of the voltage stabilizing circuit.

[0005] Optionally, when N=2, the charge pump circuit includes a first capacitor, and the charge pump circuit has two working stages:

[0006] In the first stage, the first capacitor is connected in parallel to the output end of the voltage stabilizing circuit, and the first capacitor is charged;

[0007] In the second stage, the first capacitor and the second battery are connected in parallel, and the second battery is charged.

[0008] Optionally, the charge pump circuit also includes a first switch, a second switch, a third switch and a fourth switch; the first ends of the first switch and the third switch are connected to the high potential output end of the voltage stabilizing circuit; the second end of the first switch is connected to the first end of the second switch, and the common connection end thereof is connected to the first end of the first capacitor; the second end of the third switch is connected to the first end of the fourth switch, and the common connection end thereof is connected to the second end of the first capacitor; the second end of the second switch is connected to the positive electrode of the second battery, and the second end of the fourth switch is connected to the negative electrode of the first battery.

[0009] Optionally, in the first stage, the first switch and the fourth switch are turned on; in the second stage, the second switch and the third switch are turned on.

[0010] Optionally, the duty cycle of the first switch and the fourth switch is equal to the duty cycle of the second switch and the third switch.

[0011] Optionally, the charge pump circuit includes N-1 capacitors, and the charge pump circuit operates sequentially from stage 1 to stage 2*(N-1), wherein:

[0012] In the 2N-3 stage, the N-1th capacitor is connected in parallel to the output end of the voltage stabilizing circuit, and the N-1th capacitor is charged;

[0013] In the 2N-2 stage, the N-1th capacitor is connected in parallel with the Nth battery, and the Nth battery is charged.

[0014] Optionally, the charge pump circuit further includes a first switch and N-1 switch modules; from the second battery to the Nth battery, each battery corresponds to a switch module; each switch module includes a second switch, a third switch, a fourth switch and a capacitor;

[0015] In each switch module, the first end of the second switch is connected to the high potential output end of the voltage stabilizing circuit, the second end of the second switch is connected to the first end of the third switch, the second end of the third switch is connected to the positive electrode of the corresponding battery, and the common connection end of the second switch and the third switch is connected to the first end of the corresponding capacitor; the first end of the fourth switch is connected to the second end of the corresponding capacitor, and the second end of the fourth switch is connected to the negative electrode of the corresponding battery; the first end of the first switch is connected to the second end of each capacitor, and the second end of the first switch is grounded.

[0016] Optionally, the first switch, the switch modules corresponding to the second battery, and the switch modules corresponding to the Nth battery work in sequence; each switch module corresponds to two working stages:

[0017] Phase 1: The first switch and the second switch are turned on;

[0018] In the second stage, the third switch and the fourth switch are turned on.

[0019] Optionally, the voltage stabilizing circuit is a step-down circuit, including an upper tube, a lower tube, a first inductor and an output capacitor; the first end of the upper tube receives an input voltage, and its second end is connected to the first end of the lower tube, and the second end of the lower tube is grounded; the common connection end of the upper tube and the lower tube is connected to the first end of the first inductor, and the second end of the first inductor is connected to the output capacitor.

[0020] The present invention also provides a self-balancing battery charging method for charging N batteries connected in series, wherein the negative electrode of the Nth battery is connected to the positive electrode of the N-1th battery, and N>1, and is characterized in that: the charging method is based on a voltage stabilizing circuit and a charge pump circuit, the voltage stabilizing circuit receives an input voltage, and its output end is connected to the input end of the charge pump circuit, the output end of the charge pump circuit is connected to N batteries connected in series, and the first battery is connected in parallel to the output end of the voltage stabilizing circuit; the voltage of each battery is equal to the output voltage of the voltage stabilizing circuit.

[0021] Compared with the prior art, the present invention has the following advantages: the charging method is based on a voltage stabilizing circuit and a charge pump circuit, the voltage stabilizing circuit receives an input voltage, and its output end is connected to the input end of the charge pump circuit, and the output end of the charge pump circuit is connected to N batteries connected in series, and the voltage of each battery is equal to the output voltage of the voltage stabilizing circuit. The present invention can realize automatic battery voltage balancing after the battery is fully charged. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the self-balancing battery charging circuit of the present invention;

[0023] Figure 2 This is a schematic diagram of an embodiment of a two-battery self-balancing charging circuit of the present invention; DETAILED DESCRIPTION

[0024] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, but the present invention is not limited to these embodiments. The present invention covers any substitution, modification, equivalent method and scheme made within the spirit and scope of the present invention.

[0025] In order to make the public have a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the present invention, but those skilled in the art can fully understand the present invention without the description of these details.

[0026] The present invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the accompanying drawings are all simplified and not in exact proportions, in order to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention.

[0027] like Figure 1As shown, a schematic diagram of the self-balancing battery charging circuit of the present invention is illustrated. The charging circuit is used to charge N batteries connected in series. The negative electrode of the Nth battery is connected to the positive electrode of the N-1th battery, and N>1. The charging circuit includes a voltage stabilizing circuit and a charge pump circuit. The voltage stabilizing circuit receives an input voltage, and its output end is connected to the input end of the charge pump circuit. The output end of the charge pump circuit is connected to N batteries connected in series. The first battery is connected in parallel to the output end of the voltage stabilizing circuit, and the voltage of each battery is equal to the output voltage of the voltage stabilizing circuit. The charge pump circuit includes N-1 capacitors, a first switch k1 and N-1 switch modules; from the second battery to the Nth battery, each battery corresponds to a switch module; taking the switch module corresponding to the Nth battery as an example, the second switch k1 includes a first switch k2, a second switch k3, and a second switch module k4. N 1. The third switch k N 2. The fourth switch k N 3 and a capacitor CN-1, the second switch k N 1 The first end is connected to the high potential output end of the voltage stabilizing circuit, and the second end is connected to the third switch k N 2 first terminal, third switch k N 2 The second end is connected to the positive electrode of the corresponding battery BATN, and the second switch k N 1 and the third switch k N The common connection end of the fourth switch k is connected to the first end of the corresponding capacitor CN-1; N 3 The first end is connected to the second end of the corresponding capacitor CN-1, and the fourth switch k N 3, the second end is connected to the negative electrode of the corresponding battery BATN; the first end of the first switch k1 is connected to the second end of each capacitor, and the second end of the first switch k1 is grounded. The first switch k1, the switch module corresponding to the second battery, and the switch module corresponding to the Nth battery work in sequence; each switch module corresponds to two working stages: the first stage: the first switch k1 and the second switch k N 1 is turned on; in the second stage, the third switch k N 2 and the fourth switch k N 3Conduction.

[0028] like Figure 2As shown, a schematic diagram of an embodiment of a self-balancing charging circuit for two batteries of the present invention is illustrated. The voltage stabilizing circuit is a step-down circuit, including an upper tube Q1, a lower tube Q2, a first inductor L1 and an output capacitor C0; the first end of the upper tube Q1 receives an input voltage VIN, and the second end thereof is connected to the first end of the lower tube Q2, and the second end of the lower tube Q2 is grounded; the common connection end of the upper tube Q1 and the lower tube Q2 is connected to the first end of the first inductor L1, the second end of the first inductor L2 is connected to the first end of the output capacitor C0, and the second end of the output capacitor C0 is grounded. The charge pump circuit includes a first switch Q3, a second switch Q4, a third switch Q5, a fourth switch Q6 and a first capacitor C1; the first ends of the first switch Q3 and the third switch Q5 are connected to the high potential output end of the voltage stabilizing circuit; the second end of the first switch Q3 is connected to the first end of the second switch Q4, and the common connection end thereof is connected to the second end of the first capacitor C2; the second end of the third switch Q5 is connected to the first end of the fourth switch Q6, and the common connection end thereof is connected to the second end of the first capacitor C1; the second end of the second switch Q4 is connected to the positive electrode of the second battery BAT2, and the second end of the fourth switch Q6 is connected to the negative electrode of the first battery BAT.

[0029] Although the embodiments are described and illustrated separately above, some common technologies are involved. It is the opinion of ordinary technicians in this field that the embodiments can be replaced and integrated. If the content is not clearly recorded in one of the embodiments, reference can be made to another recorded embodiment.

[0030] The above-mentioned implementation modes do not constitute a limitation on the protection scope of the technical solution. Any modification, equivalent replacement and improvement made within the spirit and principle of the above-mentioned implementation modes shall be included in the protection scope of the technical solution.

Claims

1. A self-balancing battery charging circuit for charging N batteries connected in series, wherein the negative electrode of the Nth battery is connected to the positive electrode of the N-1th battery, N>1, comprising: A voltage stabilizing circuit and a charge pump circuit, wherein the voltage stabilizing circuit receives an input voltage, and its output end is connected to the input end of the charge pump circuit, and the output end of the charge pump circuit is connected to N batteries connected in series, and the first battery is connected in parallel to the output end of the voltage stabilizing circuit; the voltage of each battery is equal to the output voltage of the voltage stabilizing circuit.

2. The self-balancing battery charging circuit according to claim 1, characterized in that: When N=2, the charge pump circuit includes a first capacitor, and the charge pump circuit has two working stages: In the first stage, the first capacitor is connected in parallel to the output end of the voltage stabilizing circuit, and the first capacitor is charged; In the second stage, the first capacitor and the second battery are connected in parallel, and the second battery is charged.

3. The self-balancing battery charging circuit according to claim 2, characterized in that: The charge pump circuit also includes a first switch, a second switch, a third switch and a fourth switch; the first ends of the first switch and the third switch are connected to the high potential output end of the voltage stabilizing circuit; the second end of the first switch is connected to the first end of the second switch, and the common connection end thereof is connected to the first end of the first capacitor; the second end of the third switch is connected to the first end of the fourth switch, and the common connection end thereof is connected to the second end of the first capacitor; the second end of the second switch is connected to the positive electrode of the second battery, and the second end of the fourth switch is connected to the negative electrode of the first battery.

4. The self-balancing battery charging circuit according to claim 3, characterized in that: In the first stage, the first switch and the fourth switch are turned on; In the second stage, the second switch and the third switch are turned on.

5. The self-balancing battery charging circuit according to claim 4, characterized in that: The duty ratios of the first switch and the fourth switch are equal to the duty ratios of the second switch and the third switch.

6. The self-balancing battery charging circuit according to claim 1, wherein: The charge pump circuit includes N-1 capacitors, and the charge pump circuit operates sequentially from the 1st stage to the 2*(N-1)th stage, wherein: In the 2N-3 stage, the N-1th capacitor is connected in parallel to the output end of the voltage stabilizing circuit, and the N-1th capacitor is charged; In the 2N-2 stage, the N-1th capacitor is connected in parallel with the Nth battery, and the Nth battery is charged.

7. The self-balancing battery charging circuit according to claim 6, characterized in that: The charge pump circuit further includes a first switch and N-1 switch modules; from the second battery to the Nth battery, each battery corresponds to a switch module; each switch module includes a second switch, a third switch, a fourth switch and a capacitor; In each switch module, the first end of the second switch is connected to the high potential output end of the voltage stabilizing circuit, the second end of the second switch is connected to the first end of the third switch, the second end of the third switch is connected to the positive electrode of the corresponding battery, and the common connection end of the second switch and the third switch is connected to the first end of the corresponding capacitor; the first end of the fourth switch is connected to the second end of the corresponding capacitor, and the second end of the fourth switch is connected to the negative electrode of the corresponding battery; the first end of the first switch is connected to the second end of each capacitor, and the second end of the first switch is grounded.

8. The self-balancing battery charging circuit according to claim 7, characterized in that: The switch modules corresponding to the first switch, the second battery, and the Nth battery work in sequence; each switch module corresponds to two working stages: Phase 1: The first switch and the second switch are turned on; Phase 2: The third switch and the fourth switch are turned on.

9. The self-balancing battery charging circuit according to any one of claims 1 to 8, characterized in that: The voltage stabilizing circuit is a step-down circuit, including an upper tube, a lower tube, a first inductor and an output capacitor; the first end of the upper tube receives an input voltage, the second end of the upper tube is connected to the first end of the lower tube, and the second end of the lower tube is grounded; the common connection end of the upper tube and the lower tube is connected to the first end of the first inductor, and the second end of the first inductor is connected to the output capacitor.

10. A self-balancing battery charging method for charging N batteries connected in series, wherein the negative electrode of the Nth battery is connected to the positive electrode of the N-1th battery, N>1, characterized in that: The charging method is based on a voltage stabilizing circuit and a charge pump circuit. The voltage stabilizing circuit receives an input voltage, and its output end is connected to the input end of the charge pump circuit. The output end of the charge pump circuit is connected to N batteries connected in series, and the first battery is connected in parallel to the output end of the voltage stabilizing circuit; the voltage of each battery is equal to the output voltage of the voltage stabilizing circuit.

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