Dual active bridge converter integrated with energy storage battery

Abstract

The invention discloses a dual-active-bridge converter integrated with an energy storage battery. The dual-active-bridge converter comprises a primary side full-bridge circuit, a secondary side full-bridge circuit, a transformer T and an energy storage module, the primary side full-bridge circuit is connected with the secondary side full-bridge circuit through the transformer T. The energy storage module is connected with the secondary side full-bridge circuit. The energy storage module comprises an inductor L2 and an inductor L3, the energy storage module comprises an inductor L2, an inductor L3, a capacitor C3 and an energy storage battery B. After the inductor L2 and the inductor L3 are connected in series, the two ends of the inductor L2 and the inductor L3 are connected with the two bridge arms of the secondary full-bridge circuit respectively, and the connecting point of the inductor L2 and the inductor L3 is connected with the capacitor C3 and the energy storage battery B. According to the dual active bridge converter integrated with the energy storage battery, the problems that in the prior art, the number of DCDC converters in a direct current micro-grid is too large, and the energy storage charging and discharging efficiency is low are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of power electronic converters, and in particular relates to a dual active bridge converter with integrated energy storage batteries. Background Art

[0002] DC microgrids are gradually being widely used due to their high energy conversion efficiency, no power quality issues such as harmonics and reactive power, and easier access to renewable energy. The dual active bridge converter has become the core power conversion device for connecting photovoltaics, energy storage, charging piles, and DC loads in DC microgrids due to its advantages such as bidirectional power flow, electrical isolation between input and output, and high conversion efficiency.

[0003] The invention patent (application number CN202411042980.1) proposes a photovoltaic storage charging and discharging integrated charging system and charging method, and the invention patent (application number CN202410575340.0) proposes a photovoltaic storage charging DC microgrid coordinated control method. The DC microgrid architecture mentioned in the two patents, photovoltaics, energy storage, charging piles, DC loads, etc. all require a DCDC converter to connect to the DC bus. There are too many of these DCDC converters, and the initial investment cost is high. In addition, when the energy storage system is charging, it is necessary to first transfer energy from the power generation equipment to the DC bus, and then to the energy storage battery. When the energy storage system is discharging, it is necessary to first transfer the energy in the energy storage battery to the DC bus and then to the corresponding electrical equipment, which will result in a longer power loop for energy storage charging and discharging and lower conversion efficiency. Summary of the invention

[0004] The purpose of the present invention is to provide a dual active bridge converter with integrated energy storage battery, which solves the problems of excessive number of DCDC converters in a DC microgrid and low energy storage charging and discharging efficiency existing in the prior art.

[0005] The technical solution adopted by the present invention is to include a primary full-bridge circuit, a secondary full-bridge circuit, a transformer T and an energy storage module; the primary full-bridge circuit is connected to the secondary full-bridge circuit through the transformer T, and the energy storage module is connected to the secondary full-bridge circuit; The energy storage module includes an inductor L2, an inductor L3, a capacitor C3 and an energy storage battery B. After the inductor L2 and the inductor L3 are connected in series, the two ends are respectively connected to the two bridge arms of the secondary full-bridge circuit, and the connection point between the inductor L2 and the inductor L3 is connected to the capacitor C3 and the energy storage battery B.

[0006] The present invention is also characterized in that: The primary full-bridge circuit includes switches S1, S2, S3 and S4, capacitor C1, inductor L1 and power supply V H , power supply V H The positive electrode is connected to one end of capacitor C1, switches S1 and S3, and the power supply V HThe negative electrode is connected to the other end of the capacitor C1, the switch tubes S2 and S4 in sequence. The switch tubes S1 and S2 are connected in series, and the switch tubes S3 and S4 are connected in series. One end of the inductor L1 is connected to the connection point A between the switch tubes S1 and S2, and the other end is connected to the connection point B between the switch tubes S3 and S4. The inductor L1 is also connected to the primary side of the transformer T, and the secondary side of the transformer T is connected to the secondary full-bridge circuit.

[0007] The secondary full-bridge circuit includes switches Q1, Q2, Q3 and Q4, capacitor C2, and power supply V L , power supply V L The positive electrode is connected to one end of capacitor C2, switch tubes Q3 and Q1, and power supply V L The negative electrode is connected to the other end of capacitor C2, switch tubes Q4 and Q2 in sequence, switch tubes Q1 and Q2 are connected in series, switch tubes Q3 and Q4 are connected in series, one end of inductor L2 is connected to the connection point C between switch tubes Q1 and Q2 and connected to the secondary side of transformer T, and the other end of inductor L3 is connected to the connection point D between Q3 and Q4 and connected to the secondary side of transformer T.

[0008] Capacitor C3 and energy storage battery B are connected to power supply V L .

[0009] Capacitor C3 and energy storage battery B are connected to power supply V L positive electrode.

[0010] Capacitor C3 and energy storage battery B are connected to power supply V L negative electrode.

[0011] The phase difference between the inductor L2 and the inductor L3 is 180°.

[0012] The current waveforms of inductor L2 and inductor L3 are triangular waves, and the current waveform of inductor L1 is trapezoidal wave.

[0013] The beneficial effects of the present invention are: The dual active bridge converter with integrated energy storage battery provided by the present invention can directly exchange power between the DC port of the dual active bridge converter and the energy storage battery, thereby reducing the power conversion link and significantly improving the conversion efficiency. At the same time, it also saves a set of DCDC converters for energy storage charging and discharging, thereby reducing the investment cost of the DC microgrid. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The energy storage battery B of the dual active bridge converter integrated with the energy storage battery of the present invention is connected to the power supply V L Circuit topology diagram of the positive electrode; Figure 2 The energy storage battery B of the dual active bridge converter integrated with the energy storage battery of the present invention is connected to the power supply V L Circuit topology diagram of the negative electrode; Figure 3The voltage and current waveform diagram of the dual active bridge converter with integrated energy storage battery of the present invention; Figure 4 This is a simulation waveform diagram of the energy storage battery port when the duty cycle of the two half bridges on the secondary side of Example 4 is equal to 0.5; Figure 5 The waveform diagram of the transformer voltage and current simulation when the duty ratio of the two half bridges on the secondary side of Example 4 is equal to 0.5; Figure 6 This is a simulation waveform diagram of the energy storage battery port when the duty cycle of the two half bridges on the secondary side of Example 5 is equal to 0.6; Figure 7 The waveform diagram of the transformer voltage and current simulation when the duty ratio of the two half bridges on the secondary side of Example 5 is equal to 0.6; Figure 8 This is a simulation waveform diagram of the energy storage battery port when the duty cycle of the two half bridges on the secondary side of Example 6 is equal to 0.4; Fig. 9 The simulation waveform of the transformer voltage and current when the duty ratio of the two half bridges on the secondary side of Example 6 is equal to 0.4 Fig.10 This is the architecture diagram of the traditional DC microgrid system. DETAILED DESCRIPTION

[0015] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0016] Example 1 The present invention provides a dual active bridge converter with integrated energy storage battery, such as Figure 1 and Figure 2 As shown, it includes a primary full-bridge circuit, a secondary full-bridge circuit, a transformer T and an energy storage module; the primary full-bridge circuit is connected to the secondary full-bridge circuit through the transformer T, and the energy storage module is connected to the secondary full-bridge circuit; The energy storage module includes an inductor L2, an inductor L3, a capacitor C3 and an energy storage battery B. After the inductor L2 and the inductor L3 are connected in series, the two ends are respectively connected to the two bridge arms of the secondary full-bridge circuit, and the connection point between the inductor L2 and the inductor L3 is connected to the capacitor C3 and the energy storage battery B.

[0017] Example 2 Based on Example 1, the primary full-bridge circuit includes switch tubes S1, S2, S3 and S4, capacitor C1, inductor L1 and power supply V H , power supply V H The positive electrode is connected to one end of capacitor C1, switches S1 and S3, and the power supply V HThe negative electrode is connected to the other end of capacitor C1, switch tubes S2 and S4 in sequence. Switch tubes S1 and S2 are connected in series, and switch tubes S3 and S4 are connected in series. One end of inductor L1 is connected to the connection point A of switch tubes S1 and S2, and the other end is connected to the connection point B of switch tubes S3 and S4. Inductor L1 is also connected to the primary side of transformer T, and the secondary side of transformer T is connected to the secondary full-bridge circuit. The secondary full-bridge circuit includes switch tubes Q1, Q2, Q3 and Q4, capacitor C2, and power supply V L , power supply V L The positive electrode is connected to one end of capacitor C2, switch tubes Q3 and Q1, and power supply V L The negative electrode is connected to the other end of capacitor C2, switch tubes Q4 and Q2 in sequence, switch tubes Q1 and Q2 are connected in series, switch tubes Q3 and Q4 are connected in series, one end of inductor L2 is connected to the connection point C of switch tubes Q1 and Q2 and connected to the secondary side of transformer T, the other end of inductor L3 is connected to the connection point D of Q3 and Q4 and connected to the secondary side of transformer T, capacitor C3 and energy storage battery B are connected to power supply V respectively L .

[0018] The phase difference between the inductor L2 and the inductor L3 is 180°, the current waveforms of the inductor L2 and the inductor L3 are triangular waves, and the waveform of the inductor L1 is a trapezoidal wave.

[0019] Example 3 The dual active bridge converter of this embodiment integrates energy storage batteries, such as Figure 1 and Figure 2 As shown, it includes a primary full-bridge circuit, a secondary full-bridge circuit, a transformer T and an energy storage module; the primary full-bridge circuit is connected to the secondary full-bridge circuit through the transformer T, and the energy storage module is connected to the secondary full-bridge circuit; The energy storage module includes an inductor L2, an inductor L3, a capacitor C3 and an energy storage battery B. The two ends of the inductor L2 and the inductor L3 are connected in series and connected to the two bridge arms of the secondary full-bridge circuit respectively. The connection point of the inductor L2 and the inductor L3 is connected to the capacitor C3 and the energy storage battery B. The primary full-bridge circuit includes switch tubes S1, S2, S3 and S4, capacitor C1, inductor L1 and power supply V H , power supply V H The positive electrode is connected to one end of capacitor C1, switches S1 and S3, and the power supply V H The negative electrode is connected to the other end of capacitor C1, switch tubes S2 and S4 in sequence. Switch tubes S1 and S2 are connected in series, and switch tubes S3 and S4 are connected in series. One end of inductor L1 is connected to the connection point A of switch tubes S1 and S2, and the other end is connected to the connection point B of switch tubes S3 and S4. Inductor L1 is also connected to the primary side of transformer T, and the secondary side of transformer T is connected to the secondary full-bridge circuit. The secondary full-bridge circuit includes switch tubes Q1, Q2, Q3 and Q4, capacitor C2, and power supply V L , power supply V L The positive electrode is connected to one end of capacitor C2, switch tubes Q3 and Q1, and power supply VL The negative electrode is connected to the other end of capacitor C2, switch tubes Q4 and Q2 in sequence, switch tubes Q1 and Q2 are connected in series, switch tubes Q3 and Q4 are connected in series, one end of inductor L2 is connected to the connection point C of switch tubes Q1 and Q2 and connected to the secondary side of transformer T, the other end of inductor L3 is connected to the connection point D of Q3 and Q4 and connected to the secondary side of transformer T, capacitor C3 and energy storage battery B are connected to power supply V respectively L .

[0020] Among them, the phase difference between inductor L2 and inductor L3 is 180°, the current waveforms of inductor L2 and inductor L3 are triangular waves, and the waveform of inductor L1 is trapezoidal wave, such as Figure 2 As shown, capacitor C3 and energy storage battery B are connected to power supply V L negative electrode.

[0021] Example 4 On the basis of Example 3, Figure 1 As shown, the capacitor C3 and the energy storage battery B are connected to the power supply V L positive electrode.

[0022] Example 5 This embodiment provides a dual active bridge converter with integrated energy storage battery, such as Figure 1 and Figure 2 As shown, the dual active bridge circuit is composed of switch tubes S1~S4, Q1~Q4, transformer T, inductor L1, and two DC bus capacitors C1 and C2. The power devices used in the primary and secondary sides are all fully controlled devices. The power size and direction transmitted between the two DC ports can be controlled by adjusting the phase shift angle between the square wave voltages generated by the primary and secondary full bridges.

[0023] Among them, the added two filter inductors L2 and L3, a filter capacitor C3 and the energy storage battery B constitute a dual active bridge converter with integrated energy storage battery. The added filter inductor and filter capacitor together with the original secondary full bridge circuit constitute an interleaved parallel buck circuit, thereby realizing bidirectional power exchange between the secondary DC port and the energy storage battery.

[0024] The secondary full-bridge circuit forms a dual active bridge circuit together with the primary full-bridge, transformer T, and inductor L1, and also forms an interleaved parallel buck circuit with the filter inductor and filter capacitor. Therefore, it can be considered that the two-stage power conversion circuit is integrated into a one-stage power conversion circuit, which saves the use of power devices and reduces costs.

[0025] like Figure 3 The figure shows the main voltage and current waveforms of the dual active bridge converter with integrated energy storage battery. The primary full-bridge circuit generates a standard square wave voltage, and the output voltage waveforms of the left and right bridge arms of the secondary full-bridge circuit are 180° out of phase, and the duty cycle of the output voltage isD The value depends on the charge and discharge direction and the voltage of the energy storage battery V B and the secondary DC port voltage V L When the energy storage battery is charging, the duty cycle D Should be greater than V B / V L , and the duty cycle D The larger the size, the faster the charging speed; when the energy storage battery is discharged, the duty cycle D Should be less than V B / V L , and the duty cycle D The smaller it is, the faster the discharge speed; The two inductors L2 and L3 are connected between the midpoint of the bridge arm and the positive pole of the battery. Since the waveforms of the two bridge arm voltages are square waves with a phase difference of 180°, the two inductor current waveforms are triangular waves with a phase difference of 180°. After filtering by the two inductors, the voltage waveform of capacitor C3 remains stable. As the carrier of power transmission in the dual active bridge circuit, the current waveform of inductor L1 is a trapezoidal wave.

[0026] Example 6 This implementation provides a verification example. The voltage of the two DC interfaces on the primary and secondary sides is set to 750V, the primary and secondary ratio of the transformer is 1:1, and the duty cycle of the two half-bridges on the secondary side is set to 0.5. The simulation waveform is as follows: Figure 4 and Figure 5 As shown. Figure 4 It can be seen that the two half-bridges on the secondary side, the filter inductor, and the filter capacitor together form an interleaved parallel buck circuit. The output voltage waveforms of the two bridge arms differ by 180°, and the current waveforms also differ by 180°. Figure 5 It can be seen that the voltage of the energy storage battery terminal capacitor C3 is 375V, which is exactly equal to the duty cycle multiplied by the secondary DC port voltage. Figure 5 It can be seen that the voltage waveform and inductor current waveform of the primary and secondary windings of the transformer are normal, and the operating characteristics of the original dual active bridge circuit are not affected by the newly added staggered parallel buck circuit. The simulation results can verify the correctness of the dual active bridge converter with integrated energy storage battery proposed in the present invention when the duty cycle is 0.5.

[0027] Example 7 This implementation provides a verification example. The voltage of the two DC interfaces on the primary and secondary sides is set to 750V, the primary and secondary ratio of the transformer is 1:1, and the duty cycle of the two half-bridges on the secondary side is set to 0.6. The simulation waveform is as follows: Figure 6 and Figure 7 As shown. Figure 6 It can be seen that the two half-bridges on the secondary side, the filter inductor, and the filter capacitor together form an interleaved parallel buck circuit. The output voltage waveforms of the two bridge arms differ by 180°, and the current waveforms also differ by 180°. It can be seen from the figure that the voltage of the energy storage battery port capacitor C3 is 450V, which is exactly equal to the duty cycle multiplied by the secondary DC port voltage. Figure 7 It can be seen that the voltage waveform and inductor current waveform of the primary and secondary windings of the transformer are normal, and the operating characteristics of the original dual active bridge circuit are not affected by the newly added staggered parallel buck circuit. The simulation results can verify the correctness of the dual active bridge converter with integrated energy storage battery proposed in the present invention when the duty cycle is greater than 0.5.

[0028] Example 8 This implementation provides a verification example. The voltage of the two DC interfaces on the primary and secondary sides is set to 750V, the primary and secondary ratio of the transformer is 1:1, and the duty cycle of the two half-bridges on the secondary side is set to 0.4. The simulation waveform is as follows: Figure 8 and Fig. 9 As shown. Figure 8 It can be seen that the two half-bridges on the secondary side, the filter inductor, and the filter capacitor together form an interleaved parallel buck circuit. The output voltage waveforms of the two bridge arms differ by 180°, and the current waveforms also differ by 180°. It can be seen from the figure that the voltage of the energy storage battery port capacitor C3 is 300V, which is exactly equal to the duty cycle multiplied by the secondary DC port voltage. Fig. 9 It can be seen that the voltage waveform and inductor current waveform of the primary and secondary windings of the transformer are normal, and the operating characteristics of the original dual active bridge circuit are not affected by the newly added staggered parallel buck circuit. The simulation results can verify the correctness of the dual active bridge converter with integrated energy storage battery proposed in this patent when the duty cycle is less than 0.5.

[0029] Comparative Example 1 like Fig.10 As shown in the figure, the system architecture of the traditional DC microgrid is to use an AC / DC converter to convert the AC grid voltage into DC to build a DC bus. Photovoltaic, energy storage, charging terminals and other equipment are connected to the DC bus through their own DC / DC converters. This leads to more power conversion links between energy storage and power generation equipment and power consumption equipment, and the conversion efficiency is low. Moreover, each device requires a DC / DC converter to connect to the DC bus, which leads to a large number of devices and high system costs.

Claims

1. A dual active bridge converter with integrated energy storage battery, characterized in that: It includes a primary full-bridge circuit, a secondary full-bridge circuit, a transformer T and an energy storage module; the primary full-bridge circuit is connected to the secondary full-bridge circuit through the transformer T, and the energy storage module is connected to the secondary full-bridge circuit; The energy storage module includes an inductor L2, an inductor L3, a capacitor C3 and an energy storage battery B. After the inductor L2 and the inductor L3 are connected in series, the two ends are respectively connected to the two bridge arms of the secondary full-bridge circuit, and the connection point between the inductor L2 and the inductor L3 is connected to the capacitor C3 and the energy storage battery B.

2. The dual active bridge converter with integrated energy storage battery according to claim 1, characterized in that: The primary full-bridge circuit includes switch tubes S1, S2, S3 and S4, capacitor C1, inductor L1 and power supply V H , the power supply V H The positive electrode is connected to one end of capacitor C1, switch tubes S1 and S3 in sequence, and the power supply V H The negative electrode is connected to the other end of the capacitor C1, the switch tubes S2 and S4 in sequence. The switch tubes S1 and S2 are connected in series, and the switch tubes S3 and S4 are connected in series. One end of the inductor L1 is connected to the connection point A of the switch tubes S1 and S2, and the other end is connected to the connection point B of the switch tubes S3 and S4. The inductor L1 is also connected to the primary side of the transformer T, and the secondary side of the transformer T is connected to the secondary full-bridge circuit.

3. The dual active bridge converter with integrated energy storage battery according to claim 2, characterized in that: The secondary full-bridge circuit includes switch tubes Q1, Q2, Q3 and Q4, capacitor C2, and power supply V L , the power supply V L The positive electrode is connected to one end of capacitor C2, switch tube Q3 and Q1 in sequence, and the power supply V L The negative electrode is connected to the other end of the capacitor C2, the switch tubes Q4 and Q2 in sequence, the switch tubes Q1 and Q2 are connected in series, the switch tubes Q3 and Q4 are connected in series, one end of the inductor L2 is connected to the connection point C of the switch tubes Q1 and Q2 and is connected to the secondary side of the transformer T, and the other end of the inductor L3 is connected to the connection point D of Q3 and Q4 and is connected to the secondary side of the transformer T.

4. The dual active bridge converter with integrated energy storage battery according to claim 3, characterized in that: The capacitor C3 and the energy storage battery B are connected to the power supply V L .

5. The dual active bridge converter with integrated energy storage battery according to claim 4, characterized in that: The capacitor C3 and the energy storage battery B are connected to the power supply V L positive electrode.

6. The dual active bridge converter with integrated energy storage battery according to claim 4, characterized in that: The capacitor C3 and the energy storage battery B are connected to the power supply V L negative electrode.

7. The dual active bridge converter with integrated energy storage battery according to claim 1, characterized in that: The phase difference between the inductor L2 and the inductor L3 is 180°.

8. The dual active bridge converter with integrated energy storage battery according to claim 1, characterized in that: The current waveforms of the inductor L2 and the inductor L3 are triangular waves, and the current waveform of the inductor L1 is a trapezoidal wave.

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