A bidirectional charging and discharging circuit and a switching power supply
By using a series branch formed by the primary winding of the transformer and the diode in the bidirectional charging and discharging circuit to clamp the voltage of the switching transistor, the problem of excessively high voltage of the switching device is solved, and the cost is reduced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- MORNSUN GUANGZHOU SCI & TECH
- Filing Date
- 2025-07-04
- Publication Date
- 2026-07-03
Smart Images
Figure CN224459276U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of energy storage battery technology, and in particular to a bidirectional charging and discharging circuit for a battery and a switching power supply. Background Technology
[0002] With the increasing demand for battery packs from applications such as electric vehicles (EVs), energy storage systems (ESS), and smart devices, optimizing battery pack performance, extending lifespan, and improving safety have become core research directions for battery management systems (BMS). Among these, battery balancing is a crucial technology for addressing inconsistencies in cell voltage or state of charge (SOC) within a battery pack, while active balancing technology, due to its high energy efficiency, is gradually becoming the mainstream solution for high-end battery management systems.
[0003] like Figure 1 The bidirectional charge / discharge circuit shown is a typical application circuit for active balancing technology. In forward operation, the battery pack charges, and the switch Q1 and diode D2 form a conventional flyback circuit to achieve constant current charging of the right battery pack. In reverse operation, the switch Q2 and diode D1 form a conventional flyback circuit to achieve constant current discharging of the right battery pack. Figure 2 The bidirectional charging and discharging circuit shown is in Figure 1 Based on the bidirectional flyback circuit shown, switching transistors Q1 and Q2 are used as synchronous rectifiers, thereby improving circuit performance while reducing power supply cost.
[0004] Both of the above technical solutions have a problem: due to the influence of leakage inductance and reflected voltage, the voltage across the switch Q1 will reach a level much higher than the bus voltage (i.e., the voltage across the left battery pack). Therefore, when selecting components, it is necessary to choose switching devices with higher withstand voltage, resulting in relatively high costs. Utility Model Content
[0005] In view of this, the technical problem to be solved by this utility model is to propose a bidirectional charging and discharging circuit and a switching power supply, which can effectively solve the problem of high voltage across the switching device caused by leakage inductance and reflected voltage in the flyback circuit while meeting the constant current charging and discharging requirements of the battery. In this way, switching devices with relatively low withstand voltage can be selected during the selection process, thereby reducing costs.
[0006] As the first aspect of this utility model, the technical solution of the provided bidirectional charging and discharging circuit is as follows:
[0007] A bidirectional charging and discharging circuit is used for battery charging and discharging, wherein: the bidirectional charging and discharging circuit includes switching transistors Q1, Q2, and Q3, diodes D1, D2, D3, D4, and D5, transformer T1, and capacitor C1;
[0008] One end of the switching transistor Q1 is connected to the positive terminal of the bus voltage, the cathode of diode D1, and the cathode of diode D3. The other end of the switching transistor Q1 is connected to the cathode of diode D2, the anode of diode D3, and one end A of the primary winding of transformer T1. One end of the switching transistor Q2 is connected to the anode of diode D2, the anode of diode D4, and the ground of the bus voltage. The other end of the switching transistor Q2 is connected to the other end B of the primary winding of transformer T1, the anode of diode D1, and the cathode of diode D4. One end of the switching transistor Q3 is connected to one end C of the secondary winding of transformer T1 and the anode of diode D5. The other end of the switching transistor Q3 is connected to the positive terminal of the output voltage and one end E of capacitor C1. The other end D of the secondary winding of transformer T1 is connected to the ground of the output voltage and the other end F of capacitor C1.
[0009] Preferably, the switching transistor Q1 is a P-type MOS transistor.
[0010] Furthermore, regardless of whether the bidirectional charging and discharging circuit is in a forward or reverse operating state, when the switching transistors Q1 and Q2 are simultaneously turned off, ignoring the voltage drop of diodes D1 and D2, the switching transistor Q1 is clamped to the bus voltage by the series branch formed by the primary winding of transformer T1 and diode D1, and the switching transistor Q2 is clamped to the bus voltage by the series branch formed by the primary winding of transformer T1 and diode D2.
[0011] A bidirectional charging and discharging circuit is used for battery charging and discharging, wherein: the bidirectional charging and discharging circuit includes switching transistors Q1, Q2, and Q3, diodes D1 and D2, transformer T1, and capacitor C1;
[0012] One end of the switching transistor Q1 is connected to the positive terminal of the bus voltage and the cathode of the diode D1, and the other end of the switching transistor Q1 is connected to the cathode of the diode D2 and one end A of the primary winding of the transformer T1; one end of the switching transistor Q2 is connected to the anode of the diode D2 and the ground of the bus voltage, and the other end of the switching transistor Q2 is connected to the other end B of the primary winding of the transformer T1 and the anode of the diode D1; one end of the switching transistor Q3 is connected to one end C of the secondary winding of the transformer T1, and the other end of the switching transistor Q3 is connected to the positive terminal of the output voltage and one end E of the capacitor C1; the other end D of the secondary winding of the transformer T1 is connected to the ground of the output voltage and the other end F of the capacitor C1.
[0013] Furthermore, the driving waveforms of the switching transistors Q1 and Q2 are exactly the same, and the driving waveform of the switching transistor Q3 is complementary to the driving waveforms of the switching transistors Q1 and Q2.
[0014] Furthermore, regardless of whether the bidirectional charging and discharging circuit is in the forward or reverse operating state, when the switching transistors Q1 and Q2 are turned off, ignoring the voltage drop of diodes D1 and D2, the switching transistor Q1 is clamped to the bus voltage by the series branch formed by the primary winding of transformer T1 and diode D1, and the switching transistor Q2 is clamped to the bus voltage by the series branch formed by the primary winding of transformer T1 and diode D2.
[0015] Furthermore, when the bidirectional charging and discharging circuit operates in the forward direction, the switch Q3 is used as a synchronous rectifier; when the bidirectional charging and discharging circuit operates in the reverse direction, the switch Q1 and the switch Q2 are used as synchronous rectifiers.
[0016] As a second aspect of this utility model, the technical solution of the provided switching power supply embodiment is as follows:
[0017] A switching power supply, wherein: it includes the bidirectional charging and discharging circuit described in any of the first aspects above.
[0018] The specific beneficial effects of this utility model are mainly reflected in the bidirectional charging and discharging circuit applied to battery charging and discharging applications. Regardless of whether it is in the forward or reverse working state, when the switching transistors Q1 and Q2 are turned off, the voltage across the switching transistors Q1 and Q2 will be clamped to the bus voltage level, thereby reducing the withstand voltage requirements of the switching transistors Q1 and Q2, and thus reducing the cost of the entire power supply. Attached Figure Description
[0019] Figure 1 This is a typical battery charging and discharging circuit in active balancing technology.
[0020] Figure 2 An improved circuit for typical battery charging and discharging in active balancing technology;
[0021] Figure 3 This is a schematic diagram of the charging and discharging circuit of the dual-tube flyback battery in the first embodiment of this utility model;
[0022] Figure 4 This is a schematic diagram of the charging and discharging circuit of the dual-tube flyback battery in the second embodiment of this utility model.
[0023] Figure 5 This is a schematic diagram of the charging and discharging circuit of the dual-tube flyback battery in the third embodiment of this utility model. Detailed Implementation
[0024] To make this utility model clearer and more understandable, the technical solution of this utility model will be described more clearly and completely below in conjunction with the accompanying drawings and specific embodiments.
[0025] Figure 3 The schematic diagram of the bidirectional charging and discharging circuit in the first embodiment of this utility model includes switching transistors Q1, Q2, and Q3, diodes D1, D2, D3, D4, and D5, transformer T1, and capacitor C1, with the following connection relationships:
[0026] One end of switch Q1 is connected to the positive terminal of the bus voltage, the cathode of diode D1, and the cathode of diode D3. The other end of switch Q1 is connected to the cathode of diode D2, the anode of diode D3, and one end A of the primary winding of transformer T1. One end of switch Q2 is connected to the anode of diode D2, the anode of diode D4, and the ground of the bus voltage. The other end of switch Q2 is connected to the other end B of the primary winding of transformer T1, the anode of diode D1, and the cathode of diode D4. One end of switch Q3 is connected to one end C of the secondary winding of transformer T1 and the anode of diode D5. The other end of switch Q3 is connected to the positive terminal of the output voltage and one end E of capacitor C1. The other end D of the secondary winding of transformer T1 is connected to the ground of the output voltage and the other end F of capacitor C1.
[0027] The working principle of the first embodiment is as follows:
[0028] When the bidirectional charging and discharging circuit operates in the forward direction, switches Q1 and Q2 are simultaneously turned on and off, while switch Q3 remains off. Switches Q1 and Q2, along with diode D5, form a flyback circuit to achieve constant current charging of the battery. When switches Q1 and Q2 are on, the voltage across the primary winding of the transformer is A positive and B negative. Diodes D1 and D2 are reverse-biased and cut off, allowing the transformer to store energy, which is then used by capacitor C1 to charge the battery pack on the right. When switches Q1 and Q2 are turned off, the transformer releases energy, and diode D5 conducts. The energy of the transformer charges the battery pack on the right through diode D5, and simultaneously charges capacitor C1 to replenish the lost energy. When switches Q1 and Q2 are turned off, since the current of the transformer's magnetizing inductance and leakage inductance cannot change abruptly, a reverse voltage will be generated across the primary winding. This voltage is B positive and A negative. When the reverse voltage across the primary winding of the transformer is higher than the voltage of the battery pack plus the forward voltage drop of diodes D1 and D2, the branches formed by the primary winding of the transformer and diodes D1 and D2 will conduct. Since the series branch formed by switch Q1, the primary winding of the transformer, and diode D1 is connected in parallel, and the series branch formed by switch Q2, the primary winding of the transformer, and diode D2 is connected in parallel, ignoring the voltage drop of diodes D1 and D2, the voltage across switches Q1 and Q2 will be clamped to the bus voltage.
[0029] When the bidirectional charging and discharging circuit operates in reverse, switches Q1 and Q2 remain off. Switch Q3, along with diodes D3 and D4, forms a flyback circuit to achieve constant current discharge from the battery. When switch Q3 is on, the transformer stores energy, with the primary winding A positive and B negative, and diodes D1 and D2 cut off. When switch Q3 is off, the transformer releases energy. When the reverse voltage (B positive, A negative) generated by the transformer's magnetizing inductance and leakage inductance in the primary winding exceeds the battery voltage plus the forward voltage drop of diodes D1 and D2, the branch formed by the primary winding and diodes D1 and D2 will conduct. Since the series branch formed by switch Q1 and the primary winding and diode D1 is connected in parallel, and the series branch formed by switch Q2 and the primary winding and diode D2 is also connected in parallel, ignoring the voltage drop of diodes D1 and D2, the voltages across switches Q1 and Q2 will be clamped to the bus voltage.
[0030] Figure 4 The schematic diagram of the bidirectional charging and discharging circuit in the second embodiment of this utility model includes switching transistors Q1, Q2, and Q3, diodes D1 and D2, transformer T1, and capacitor C1, with the following connection relationships:
[0031] One end of switch Q1 is connected to the positive terminal of the bus voltage and the cathode of diode D1; the other end of switch Q1 is connected to the cathode of diode D2 and one end A of the primary winding of transformer T1. One end of switch Q2 is connected to the anode of diode D2 and the ground of the bus voltage; the other end of switch Q2 is connected to the other end B of the primary winding of transformer T1 and the anode of diode D1. One end of switch Q3 is connected to one end C of the secondary winding of transformer T1; the other end of switch Q3 is connected to the positive terminal of the output voltage and one end E of capacitor C1. The other end D of the secondary winding of transformer T1 is connected to the ground of the output voltage and the other end F of capacitor C1.
[0032] The working principle of this embodiment is basically the same as that of the first embodiment. However, regardless of whether it is working in the forward or reverse direction, the diode used for rectification is replaced by a switching transistor connected in parallel and working in the synchronous rectification state, thereby improving power supply performance while further reducing costs.
[0033] Figure 5 The schematic diagram of the bidirectional charging and discharging circuit in the third embodiment of this utility model includes switching transistors Q1, Q2, and Q3, diodes D1 and D2, and transformer T1. The device connection relationship and working principle in this embodiment are the same as those in the second embodiment, and will not be repeated here. It should be noted that in the third embodiment, switching transistor Q1 adopts a P-type semiconductor, thereby solving the high-end drive problem and further reducing costs.
[0034] It should be noted that the types of switching transistors Q1, Q2, and Q3 in the accompanying drawings of this utility model are merely examples. Those skilled in the art can select them as needed. Preferably, switching transistor Q1 is a P-type MOSFET to solve the problem of high-side drive and reduce costs.
[0035] The above are merely preferred embodiments of this utility model. It should be noted that the above preferred embodiments should not be considered as limitations on this utility model, and the scope of protection of this utility model should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of this utility model, such as specifically selecting a novel device like gallium nitride for the switching transistor, and specifically selecting a Schottky diode for the diode connected in parallel across the switching transistor. These improvements and modifications should also be considered within the scope of protection of this utility model.
Claims
1. A bidirectional charge-discharge circuit applied to battery charge-discharge, characterized in that: The bidirectional charging and discharging circuit includes switching transistors Q1, Q2, and Q3, diodes D1, D2, D3, D4, and D5, transformer T1, and capacitor C1. One end of the switching transistor Q1 is connected to the positive terminal of the bus voltage, the cathode of diode D1, and the cathode of diode D3. The other end of the switching transistor Q1 is connected to the cathode of diode D2, the anode of diode D3, and one end A of the primary winding of transformer T1. One end of the switching transistor Q2 is connected to the anode of diode D2, the anode of diode D4, and the ground of the bus voltage. The other end of the switching transistor Q2 is connected to the other end B of the primary winding of transformer T1, the anode of diode D1, and the cathode of diode D4. One end of the switching transistor Q3 is connected to one end C of the secondary winding of transformer T1 and the anode of diode D5. The other end of the switching transistor Q3 is connected to the positive terminal of the output voltage and one end E of capacitor C1. The other end D of the secondary winding of transformer T1 is connected to the ground of the output voltage and the other end F of capacitor C1.
2. The bidirectional charging and discharging circuit of claim 1, wherein: The switching transistor Q1 is a P-type MOS transistor.
3. The bidirectional charging and discharging circuit of claim 1, wherein: Regardless of whether the bidirectional charging and discharging circuit is in the forward or reverse operating state, when the switching transistors Q1 and Q2 are simultaneously turned off, ignoring the voltage drop of diodes D1 and D2, the switching transistor Q1 is clamped to the bus voltage by the series branch formed by the primary winding of transformer T1 and diode D1, and the switching transistor Q2 is clamped to the bus voltage by the series branch formed by the primary winding of transformer T1 and diode D2.
4. A bidirectional charging and discharging circuit, used for battery charging and discharging, characterized in that: The bidirectional charging and discharging circuit includes switching transistors Q1, Q2, and Q3, diodes D1 and D2, transformer T1, and capacitor C1. One end of the switching transistor Q1 is connected to the positive terminal of the bus voltage and the cathode of the diode D1, and the other end of the switching transistor Q1 is connected to the cathode of the diode D2 and one end A of the primary winding of the transformer T1; one end of the switching transistor Q2 is connected to the anode of the diode D2 and the ground of the bus voltage, and the other end of the switching transistor Q2 is connected to the other end B of the primary winding of the transformer T1 and the anode of the diode D1; one end of the switching transistor Q3 is connected to one end C of the secondary winding of the transformer T1, and the other end of the switching transistor Q3 is connected to the positive terminal of the output voltage and one end E of the capacitor C1; the other end D of the secondary winding of the transformer T1 is connected to the ground of the output voltage and the other end F of the capacitor C1.
5. The bidirectional charging and discharging circuit of claim 4, wherein: The driving waveforms of the switching transistors Q1 and Q2 are exactly the same, and the driving waveform of the switching transistor Q3 is complementary to the driving waveforms of the switching transistors Q1 and Q2.
6. The bidirectional charge and discharge circuit of claim 4, wherein: Regardless of whether the bidirectional charging and discharging circuit is in the forward or reverse operating state, when the switching transistors Q1 and Q2 are turned off, ignoring the voltage drop of diodes D1 and D2, the switching transistor Q1 is clamped to the bus voltage by the series branch formed by the primary winding of transformer T1 and diode D1, and the switching transistor Q2 is clamped to the bus voltage by the series branch formed by the primary winding of transformer T1 and diode D2.
7. The bidirectional charging and discharging circuit of claim 4, wherein: When the bidirectional charging and discharging circuit operates in the forward direction, the switch Q3 is used as a synchronous rectifier; when the bidirectional charging and discharging circuit operates in the reverse direction, the switch Q1 and the switch Q2 are used as synchronous rectifiers.
8. A switching power supply characterized by comprising: Includes the bidirectional charging and discharging circuit as described in any one of claims 1 to 7.