Asymmetric half-bridge flyback cell charging and discharging test system

Abstract

The utility model discloses an asymmetric half-bridge flyback cell charging and discharging test system, which relates to the technical field of battery charging and discharging and comprises a bidirectional ACDC module and a bidirectional isolation DCDC module. One end of the bidirectional ACDC module is connected with a power grid, the other end of the bidirectional ACDC module is connected with one end of the bidirectional isolation DCDC module, and the other end of the bidirectional isolation DCDC module is connected with the battery cell; the bidirectional ACDC module is used for realizing bidirectional energy flow between alternating current of a power grid and a direct current bus, and the bidirectional isolation DCDC module adopts an asymmetric half-bridge flyback topology to directly control a battery cell to charge and discharge. According to the utility model, energy is stored by using the resonant capacitor and the transformer through asymmetric half-bridge flyback, energy transmission between the primary and the secondary is realized through the high-frequency power transformer, zero-voltage switching-on and zero-current switching-off of the power switch tube are realized at the same time, switching loss is reduced, and efficiency is improved.

Description

Technical Field

[0001] This utility model relates to the field of battery charging and discharging technology, specifically to an asymmetric half-bridge flyback battery cell charging and discharging test system. Background Technology

[0002] The rapid development of new energy and energy storage technologies is accelerating the global energy system's transformation towards cleaner and lower-carbon energy. Against this backdrop, battery technology breakthroughs, as the core carrier of energy storage and release, are directly related to the industrialization process of key areas such as electric vehicles, smart grids, and distributed energy storage. As the smallest functional unit of a battery system, the reliability of the battery cell not only affects the cycle life and safety performance of the battery module but also determines the operational stability of the entire energy system.

[0003] like Figure 5 As shown, current mainstream battery cell charging and discharging testing systems generally adopt a three-stage power conversion architecture: the first-stage bidirectional AC / DC module realizes the energy conversion between the grid AC power and the DC bus, the second-stage bidirectional isolated DC / DC module is used to establish safe electrical isolation and adjust the voltage level, and the final-stage bidirectional non-isolated DC / DC module is responsible for completing the precise charging and discharging control of the battery cell.

[0004] While this multi-stage series structure can meet basic testing requirements, it has significant technical limitations in practical applications. Each power conversion stage generates corresponding energy losses, with a large amount of electrical energy wasted in the intermediate conversion processes. Cascaded control between power modules requires the coordinated operation of multiple closed-loop systems, significantly increasing the difficulty of parameter tuning and easily leading to problems such as dynamic response hysteresis and loop interference, directly affecting the tracking accuracy of the test curve. Therefore, these technical limitations not only restrict the production capacity ramp-up speed of battery manufacturers but also keep the R&D investment and maintenance costs of testing equipment high, making it difficult to match the urgent needs of the new energy industry for efficient and intensive production models.

[0005] In response to the existing problems, there is an urgent need for a reliable solution that can both improve conversion efficiency and reduce the cost of charge and discharge testing systems. Utility Model Content

[0006] To address the problems in related technologies, this utility model proposes an asymmetric half-bridge flyback cell charge and discharge testing system to overcome the aforementioned technical problems existing in the prior art.

[0007] Therefore, the specific technical solution adopted by this utility model is as follows:

[0008] A cell charge-discharge testing system for an asymmetric half-bridge flyback inverter includes:

[0009] Bidirectional ACDC module and bidirectional isolated DCCDC module;

[0010] One end of the bidirectional ACCDC module is connected to the power grid, and the other end of the bidirectional ACCDC module is connected to one end of the bidirectional isolated DCCDC module. The other end of the bidirectional isolated DCCDC module is connected to the battery cell.

[0011] The bidirectional AC-DC module is used to realize bidirectional energy flow between the AC power and the DC bus of the power grid. The bidirectional isolated DC-DC module adopts an asymmetric half-bridge flyback topology to directly control the charging and discharging of the battery cells.

[0012] Furthermore, the bidirectional isolated DC-DC module includes: a main control MCU unit, a first power drive unit, a second power drive unit, a third power drive unit, a first power switch, a second power switch, a third power switch, a first diode, a second diode, a third diode, a resonant capacitor, a resonant inductor, an input capacitor, an output capacitor, a high-frequency power transformer, a cell voltage sampling unit, an output current sampling unit, and an input voltage sampling unit;

[0013] The positive terminal of the input capacitor is connected to the positive terminal of the bidirectional AC-CDC module, the drain of the first power switch, one end of the resonant capacitor, and the cathode of the first diode. The negative terminal of the input capacitor is connected to the source of the second power switch, the anode of the second diode, and the primary ground of the asymmetric half-bridge. The source of the first power switch is connected to the drain of the second power switch, the anode of the first diode, the cathode of the second diode, and one end of the primary winding of the high-frequency power transformer. The other end of the resonant capacitor is connected to one end of the resonant inductor, and the other end of the resonant inductor is connected to the other end of the primary winding of the high-frequency power transformer.

[0014] One end of the secondary winding of the high-frequency power transformer is connected to the positive terminal of the output capacitor and one end of the output current sampling unit, respectively. The other end of the output current sampling unit is connected to the positive terminal of the battery cell. The negative terminal of the output capacitor is grounded. The other end of the secondary winding of the high-frequency power transformer is connected to the drain of the third power switch and the cathode of the third diode, respectively. The source of the third power switch is connected to the anode of the third diode and the cathode of the battery cell, respectively.

[0015] The gate of the first power switch is connected to one end of the first power drive unit, the gate of the second power switch is connected to one end of the second power drive unit, and the gate of the third power switch is connected to one end of the third power drive unit. The other ends of the first power drive unit, the second power drive unit, and the third power drive unit are all connected to the main control MCU unit. The two ends of the input capacitor are connected in parallel with the input voltage sampling unit, and the two ends of the battery cell are connected in parallel with the battery cell voltage sampling unit. The input voltage sampling unit, the output current sampling unit, and the battery cell voltage sampling unit are all connected in communication with the main control MCU unit.

[0016] Furthermore, the first, second, and third power switches are all superjunction metal-oxide-semiconductor field-effect transistors, used for commutation of the main power circuit.

[0017] Furthermore, the resonant capacitor, resonant inductor, and high-frequency power transformer are kept in series on the primary side for the recovery and utilization of leakage inductance energy, while simultaneously achieving zero-voltage turn-on of the main switch and zero-current turn-off of the synchronous rectifier.

[0018] Furthermore, the main control MCU unit is used for feedback control of the constant voltage loop and constant current loop, and independently controls the turn-on and turn-off of the first power switch, the second power switch and the third power switch.

[0019] Furthermore, the first power drive unit, the second power drive unit, and the third power drive unit all include an optocoupler drive circuit and a drive power supply.

[0020] Furthermore, the cell voltage sampling unit is used to sample the cell voltage; the output current sampling unit is used to sample the cell charging and discharging current; and the input voltage sampling unit is used to sample the input side voltage.

[0021] The beneficial effects of this invention are as follows: by using an asymmetric half-bridge flyback to store energy through a resonant capacitor and a transformer, and by using a high-frequency power transformer to achieve energy transfer between the primary and secondary sides, the invention also achieves zero-voltage turn-on and zero-current turn-off of the power switching transistors, thereby reducing switching losses and improving efficiency. Compared with the traditional three-level architecture, this invention adopts a two-level architecture, which can completely replace the combination design of LLC and BUCK-BOOST, thereby reducing the design cost of the system. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a system schematic diagram of an asymmetric half-bridge flyback battery cell charge-discharge test system according to an embodiment of the present invention.

[0024] Figure 2 This is an equivalent model of a high-frequency power transformer in an asymmetric half-bridge flyback cell charge-discharge test system according to an embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram of the power drive unit structure in an asymmetric half-bridge flyback battery cell charge-discharge test system according to an embodiment of the present utility model.

[0026] Figure 4 This is a block diagram of a two-level architecture battery cell charge-discharge test system designed according to an embodiment of the present invention.

[0027] Figure 5 This is a block diagram of a traditional three-level architecture battery cell charge and discharge test system. Detailed Implementation

[0028] According to an embodiment of the present invention, an asymmetric half-bridge flyback cell charge-discharge test system is provided.

[0029] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments, such as... Figures 1-4 As shown, the asymmetric half-bridge flyback battery cell charge-discharge test system according to an embodiment of the present invention includes:

[0030] Bidirectional ACDC module and bidirectional isolated DCCDC module;

[0031] One end of the bidirectional ACCDC module is connected to the power grid, and the other end of the bidirectional ACCDC module is connected to one end of the bidirectional isolated DCCDC module. The other end of the bidirectional isolated DCCDC module is connected to the battery cell.

[0032] The bidirectional AC-DC module is used to realize bidirectional energy flow between the AC power and the DC bus of the power grid. The bidirectional isolated DC-DC module adopts an asymmetric half-bridge flyback topology to directly control the charging and discharging of the battery cells.

[0033] In one embodiment, such as Figure 1 As shown, the bidirectional isolated DC-DC module includes: a main control MCU unit, a first power drive unit, a second power drive unit, a third power drive unit, a first power switch Q1, a second power switch Q2, a third power switch Q3, a first diode D1, a second diode D2, a third diode D3, a resonant capacitor Cr, a resonant inductor Lr, an input capacitor Cin, an output capacitor Cout, a high-frequency power transformer T1, a cell voltage sampling unit, an output current sampling unit, and an input voltage sampling unit;

[0034] The positive terminal of the input capacitor Cin is connected to the positive terminal of the bidirectional ACCDC module, the drain of the first power switch Q1, one end of the resonant capacitor Cr, and the cathode of the first diode D1. The negative terminal of the input capacitor Cin is connected to the source of the second power switch Q2, the anode of the second diode D2, and the primary ground of the asymmetric half-bridge. The source of the first power switch Q1 is connected to the drain of the second power switch Q2, the anode of the first diode D1, the cathode of the second diode D2, and one end of the primary winding of the high-frequency power transformer T1. The other end of the resonant capacitor Cr is connected to one end of the resonant inductor Lr, and the other end of the resonant inductor Lr is connected to the other end of the primary winding of the high-frequency power transformer T1.

[0035] One end of the secondary winding of the high-frequency power transformer T1 is connected to the positive terminal of the output capacitor Cout and one end of the output current sampling unit, respectively. The other end of the output current sampling unit is connected to the positive terminal of the battery cell. The negative terminal of the output capacitor Cout is grounded. The other end of the secondary winding of the high-frequency power transformer T1 is connected to the drain of the third power switch Q3 and the cathode of the third diode D3, respectively. The source of the third power switch Q3 is connected to the anode of the third diode D3 and the cathode of the battery cell, respectively.

[0036] The gate of the first power switch Q1 is connected to one end of the first power drive unit, the gate of the second power switch Q2 is connected to one end of the second power drive unit, and the gate of the third power switch Q3 is connected to one end of the third power drive unit. The other ends of the first power drive unit, the second power drive unit, and the third power drive unit are all connected to the main control MCU unit. The two ends of the input capacitor Cin are connected in parallel with the input voltage sampling unit, and the two ends of the battery cell are connected in parallel with the battery cell voltage sampling unit. The input voltage sampling unit, the output current sampling unit, and the battery cell voltage sampling unit are all connected in communication with the main control MCU unit.

[0037] In one embodiment, the first power switch, the second power switch, and the third power switch are all superjunction metal-oxide-semiconductor field-effect transistors, used for commutation of the main power circuit.

[0038] In one embodiment, the resonant capacitor, resonant inductor, and high-frequency power transformer T1 are kept in series on the primary side for the recovery and utilization of leakage inductance energy, while simultaneously achieving zero-voltage turn-on of the main switch and zero-current turn-off of the synchronous rectifier.

[0039] In one embodiment, the main control MCU unit is used for feedback control of the constant voltage loop and constant current loop, and independently controls the turn-on and turn-off of the first power switch, the second power switch and the third power switch.

[0040] In one embodiment, such as Figure 3 As shown, the first power drive unit, the second power drive unit, and the third power drive unit all include an optocoupler drive circuit and a drive power supply.

[0041] In one embodiment, the cell voltage sampling unit is used to sample the cell voltage; the output current sampling unit is used to sample the cell charging and discharging current; and the input voltage sampling unit is used to sample the input side voltage.

[0042] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] like Figure 1 As shown, the asymmetric half-bridge flyback cell charge and discharge test system includes a power grid, a bidirectional AC-DC module, and a bidirectional isolated DC-DC module. One end of the bidirectional AC-DC module is connected to the power grid, and the other end is connected to the bidirectional isolated DC-DC module. One end of the bidirectional isolated DC-DC module is connected to the bidirectional AC-DC module, and the other end is connected to the cell. The bidirectional isolated DC-DC module is an asymmetric half-bridge flyback topology.

[0044] The asymmetric half-bridge flyback (bidirectional isolated DC-DC module) includes an input capacitor Cin, power switches Q1, Q2, and Q3, a resonant capacitor Cr, a resonant inductor Lr, a high-frequency power transformer T1, three power drive units, a main control MCU unit, an output capacitor Cout, an output voltage sampling unit, an output current sampling unit, and a cell voltage sampling unit.

[0045] The power switch Q1 includes a parasitic diode D1, the power switch Q2 includes a parasitic diode D2, and the power switch Q3 includes a parasitic diode D3.

[0046] like Figure 2 As shown, the corresponding terminals of the high-frequency power transformer T1 are marked with black dots.

[0047] The positive terminal of the input capacitor Cin is connected to the positive terminal of the bidirectional ACCDC module, and the negative terminal is connected to the negative terminal of the bidirectional ACCDC module, and is also connected to the primary ground of the asymmetric half-bridge. The drain of Q1 is connected to the positive terminal of Cin, the source of Q1 is connected to the drain of Q2, and the source of Q2 is connected to the primary ground. The resonant capacitor Cr and the resonant inductor Lr are connected in series with the primary side of the high-frequency power transformer T1, and then connected in parallel with Q1. One end of the secondary side of the high-frequency power transformer T1 is connected to the positive terminal of the output capacitor Cout, and the other end is connected to the drain of Q3. The source of Q3 is connected to the negative terminal of the output capacitor Cout, and is also connected to the secondary ground of the asymmetric half-bridge. The input voltage sampling unit samples the voltage of Cin and sends it to the main control MCU unit. The cell voltage sampling unit samples the voltage across the two ends of the cell and sends it to the main control MCU unit. The output current sampling unit is connected in series between the output capacitor Cout and the cell, samples the charging and discharging current of the cell, and sends it to the main control MCU unit.

[0048] The specific working principle is as follows:

[0049] When the circuit is charging the battery cell in the forward direction:

[0050] 1. When Q2 is turned on, the primary current of the high-frequency power transformer T1 increases, and the voltage of the resonant capacitor Cr increases. Both store energy, and the secondary winding Q3 is turned off. At this time, no energy is transferred to the secondary winding.

[0051] 2. When the turn-on time of Q2 reaches the turn-on time controlled by the internal feedback loop, Q2 turns off. Due to the freewheeling current of the inductor (including the magnetizing inductor, resonant inductor, and leakage inductor), the parasitic diode D1 of Q1 turns on, and the leakage inductance energy is stored in Cr. Subsequently, Q1 can achieve zero-voltage turn-on. Since the secondary voltage of the high-frequency power transformer T1 is still less than the output voltage, Q3 turns off. At this time, there is no ability to transmit to the secondary side.

[0052] 3. When the secondary voltage of the high-frequency power transformer T1 is greater than the output voltage, the body diode D3 of Q3 is turned on, and Q3 is turned on at this time, realizing zero-voltage turn-on of Q3. The primary excitation inductance of the high-frequency power transformer is clamped by the output voltage, and the resonant capacitor Cr and the energy stored in the transformer are transferred to the secondary side.

[0053] 4. When the primary excitation inductor current of the high-frequency power transformer is equal to zero, since Q1 continues to be turned on, the Cr voltage reverses to excite the inductor. Part of the energy of Cr is provided to the secondary side, and part of it flows back to the excitation inductor. When the primary inductor current is equal to the excitation inductor current, the secondary current is zero. At this time, Q3 is turned off, realizing zero-current turn-off of Q3.

[0054] 5. When a new cycle begins, Q1 is turned off. Due to the freewheeling current of the high-frequency power transformer inductor, the parasitic diode D2 of Q2 turns on, achieving zero-voltage turn-on of Q2.

[0055] When the battery cell discharges, the switching loss of Q3 is relatively small due to the low cell voltage. To simplify control, Q3 is designed as a hard switch, and the process is as follows:

[0056] 1. When Q3 is turned on, the secondary current of the high-frequency power transformer increases, and energy is stored in the transformer and Cr. When Q1 and Q2 are turned off, no energy is transferred to the primary side.

[0057] 2. When the turn-on time of Q3 reaches the turn-on time controlled by the internal feedback loop, Q3 turns off. Since the voltage superimposed on the primary side voltage of the high-frequency power transformer Cr is less than the input Cin voltage, no energy is transferred to the primary side at this time.

[0058] 3. When the primary voltage of the high-frequency power transformer plus the Cr voltage is greater than the input Cin voltage, the parasitic diode D2 of Q2 conducts, realizing zero-voltage turn-on of Q2.

[0059] 4. When a new cycle begins, Q3 is activated; this is a hard activation.

[0060] In summary, by utilizing the above-mentioned technical solution of this utility model, energy is stored by using a resonant capacitor and transformer through an asymmetric half-bridge flyback, and energy transfer between the primary and secondary sides is realized through a high-frequency power transformer. At the same time, zero-voltage turn-on and zero-current turn-off of the power switching transistors are achieved, reducing switching losses and improving efficiency. Compared with the traditional three-stage architecture, this utility model adopts a two-stage architecture, which can completely replace the combination design of LLC and BUCK-BOOST, thereby reducing the system design cost.

[0061] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An asymmetric half-bridge flyback electric core charging and discharging test system, characterized in that, include: Bidirectional ACDC module and bidirectional isolated DCCDC module; One end of the bidirectional ACDC module is connected to the power grid, the other end of the bidirectional ACDC module is connected to one end of the bidirectional isolated DC-CDC module, and the other end of the bidirectional isolated DC-CDC module is connected to the battery cell. The bidirectional AC-DC module is used to realize bidirectional energy flow between the AC power and the DC bus of the power grid. The bidirectional isolated DC-DC module adopts an asymmetric half-bridge flyback topology to directly control the charging and discharging of the battery cells.

2. The asymmetric half-bridge flyback electric core charging and discharging test system according to claim 1, characterized in that, The bidirectional isolated DC-DC module includes: a main control MCU unit, a first power drive unit, a second power drive unit, a third power drive unit, a first power switch, a second power switch, a third power switch, a first diode, a second diode, a third diode, a resonant capacitor, a resonant inductor, an input capacitor, an output capacitor, a high-frequency power transformer, a cell voltage sampling unit, an output current sampling unit, and an input voltage sampling unit. The positive terminal of the input capacitor is connected to the positive terminal of the bidirectional ACDC module, the drain of the first power switch, one end of the resonant capacitor, and the cathode of the first diode. The negative terminal of the input capacitor is connected to the source of the second power switch, the anode of the second diode, and the primary ground of the asymmetric half-bridge. The source of the first power switch is connected to the drain of the second power switch, the anode of the first diode, the cathode of the second diode, and one end of the primary winding of the high-frequency power transformer. The other end of the resonant capacitor is connected to one end of the resonant inductor, and the other end of the resonant inductor is connected to the other end of the primary winding of the high-frequency power transformer. One end of the secondary winding of the high-frequency power transformer is connected to the positive terminal of the output capacitor and one end of the output current sampling unit, respectively. The other end of the output current sampling unit is connected to the positive terminal of the battery cell. The negative terminal of the output capacitor is grounded. The other end of the secondary winding of the high-frequency power transformer is connected to the drain of the third power switch and the cathode of the third diode, respectively. The source of the third power switch is connected to the anode of the third diode and the cathode of the battery cell, respectively. The gate of the first power switch is connected to one end of the first power drive unit, the gate of the second power switch is connected to one end of the second power drive unit, and the gate of the third power switch is connected to one end of the third power drive unit. The other ends of the first power drive unit, the second power drive unit, and the third power drive unit are all connected to the main control MCU unit. The two ends of the input capacitor are connected in parallel with the input voltage sampling unit, and the two ends of the battery cell are connected in parallel with the battery cell voltage sampling unit. The input voltage sampling unit, the output current sampling unit, and the battery cell voltage sampling unit are all connected in communication with the main control MCU unit.

3. The asymmetric half-bridge flyback electric core charging and discharging test system according to claim 2, characterized in that, The first power switch, the second power switch, and the third power switch are all superjunction metal-oxide field-effect transistors, used for commutation of the main power circuit.

4. The asymmetric half-bridge flyback electric core charging and discharging test system according to claim 2, characterized in that, The resonant capacitor, the resonant inductor, and the high-frequency power transformer are connected in series on the primary side for the recovery and utilization of leakage inductance energy, while simultaneously achieving zero-voltage turn-on of the main switch and zero-current turn-off of the synchronous rectifier.

5. The asymmetric half-bridge flyback electric core charge and discharge test system according to claim 2, characterized in that, The main control MCU unit is used for feedback control of the constant voltage loop and constant current loop, and independently controls the turn-on and turn-off of the first power switch, the second power switch and the third power switch.

6. The asymmetric half-bridge flyback electric core charging and discharging test system according to claim 2, characterized in that, The first power drive unit, the second power drive unit, and the third power drive unit all include an optocoupler drive circuit and a drive power supply.

7. The asymmetric half-bridge flyback electric core charge and discharge test system according to claim 2, characterized in that, The cell voltage sampling unit is used to sample the cell voltage; the output current sampling unit is used to sample the cell charging and discharging current; and the input voltage sampling unit is used to sample the input voltage.

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