A high-frequency isolation conversion device of direct-current inversion multiplexing type

Abstract

The application discloses a DC inversion multiplexing high-frequency isolation conversion device, which can be composed of two or three H-H full-bridge modules, two H-H full-bridge modules can form a single-phase alternating current interface, and three H-H full-bridge modules can form a three-phase alternating current interface. The input end of the modules is connected with the input end, and the output end is connected with the output end. When all the module No. 1 ports are connected with the No. 1 ports, the No. 2 ports are connected with the No. 2 ports, and the No. 1 ports and the No. 2 ports provide external wiring ports, a DC port is formed. When all the module No. 2 ports are connected with each other and do not provide external wiring ports, all the No. 1 ports are not connected with each other and all provide external wiring ports, an alternating current port is formed. The application adopts different interface connection modes, can become a DC-AC inverter, a DC-DC direct current converter and an AC-DC rectifier converter, energy can flow in two directions, and DC inversion multiplexing high-frequency isolation conversion is realized.

Description

Technical Field

[0001] This invention relates to a DC inverter multiplexing type high-frequency isolation converter, belonging to the field of power electronic conversion, and is specifically applicable to any AC and DC conversion application. Background Technology

[0002] In applications such as new energy microgrids, AC / DC distribution networks, and all-electric ships, AC and DC power grids coexist within the power grid and are closely interconnected. Typically, DC-DC converters are needed to connect DC power grids of different voltages, and DC-AC converters are needed to connect DC and AC power grids. Furthermore, energy needs to be able to flow bidirectionally between the power grids.

[0003] DC-DC converters and DC-AC converters are typically completely different devices and cannot be used interchangeably. Furthermore, with increasing demands for energy efficiency, higher power density requirements, and the need for inter-grid safety isolation, DC-DC converters often employ high-frequency isolation soft-switching topologies. In contrast, traditional DC-AC converters must be equipped with bulky power frequency isolation transformers and cannot achieve soft switching, resulting in low efficiency.

[0004] Therefore, in order to provide an efficient and universal solution for interconnecting power grids of different electrical systems, a universal, efficient, high-power-density interconnection device with electrical safety isolation is needed. Summary of the Invention

[0005] To address the above problems, this invention proposes a DC inverter multiplexing type high-frequency isolation converter, characterized in that the DC inverter multiplexing type high-frequency isolation converter includes two or three HH full-bridge modules for performing DC-AC isolation conversion.

[0006] Each of the HH full-bridge modules includes two DC capacitors C1 and C2, two H full-bridge capacitors Q1 and Q2, and one high-frequency isolation transformer T1;

[0007] The first and second input terminals on the input side are connected to DC capacitor C1. C1 is connected to H full-bridge Q1. Q1 is connected to the primary side of high-frequency isolation transformer T1. The secondary side of high-frequency isolation transformer T1 is connected to H full-bridge Q2. Q2 is connected to DC capacitor C2. C2 is connected to the first and second output terminals on the output side.

[0008] The first input terminals of the multiple HH full-bridge modules are interconnected and provide external wiring to connect to the external DC positive terminal DC1; the second input terminals of the multiple HH full-bridge modules are interconnected and provide external wiring to connect to the external DC negative terminal DC2.

[0009] The second output terminals of multiple HH full-bridge modules are interconnected and do not provide output lines; the first output terminals of the HH full-bridge modules are respectively used as two-phase or three-phase AC power.

[0010] Furthermore, the H-bridge Q1 shown includes a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4; the H-bridge Q2 includes a fifth switch S5, a sixth switch S6, a seventh switch S7, and an eighth switch S8. The positive terminal of the DC capacitor C1 is connected to the collectors of the first switch S1 and the third switch S3, and the negative terminal of the DC capacitor C1 is connected to the emitters of the second switch S2 and the fourth switch S4. The emitter of the first switch S1 is connected to the collector of the second switch S2 and the upper end of the primary winding of the transformer T1, and the emitter of the third switch S3 is connected to the collector of the fourth switch S4 and the lower end of the primary winding of the transformer T1. The positive terminal of DC capacitor C2 is connected to the collectors of the fifth switch S5 and the seventh switch S7, and the negative terminal of DC capacitor C2 is connected to the emitters of the sixth switch S6 and the eighth switch S8. The emitter of the fifth switch S5 is connected to the collector of the sixth switch S6 and the lower end of the secondary winding of transformer T1, and the emitter of the seventh switch S7 is connected to the collector of the eighth switch S8 and the upper end of the secondary winding of transformer T1.

[0011] Furthermore, all HH full-bridge modules adopt a phase-shift control strategy, and the switching transistors S1 to S8 have the same switching frequency and duty cycle. The drive signals of S1 to S4 and S5 to S8 will generate a phase difference PH according to the actual port voltage.

[0012] Furthermore, the DC inverter multiplexing high-frequency isolation converter shown includes three HH full-bridge modules;

[0013] The first HH full-bridge module M1 is given the output port voltage command V. a +V d V a =M×Sin(w×t+pha), V a The target value of phase A AC voltage, V d It is a DC bias value, and V d >M;

[0014] The feedback is the voltage V across the second DC capacitor C2 of the first HH full-bridge module M1. o1 The PI closed-loop control is adopted to regulate the output phase difference PHA, which is sent to the first HH full-bridge module M1. The drive signal is distributed to the switching transistors S1 to S8 according to the phase difference PHA.

[0015] The second HH full-bridge module M2 provides the output port voltage command V. b +Vd V b =M×Sin(w×t+phb), where is the target value of the phase B AC voltage, V d It is a DC bias value, and V d >M;

[0016] The feedback is the voltage V across the second DC capacitor C2 of the HH full-bridge module M2. o2 The PI closed-loop control is adopted to regulate the output phase difference PHb, which is sent to the second HH full-bridge module M2. The drive signal is distributed to the switching transistors S1 to S8 according to the phase difference PHb.

[0017] The third HH full-bridge module M3 provides the output port voltage command V. c +V d V c =M×Sin(w×t+phc), where is the target value of the C-phase AC voltage, V d It is a DC bias value, and V d >M;

[0018] The feedback is the voltage V across the second DC capacitor C2 of the HH full-bridge module M3. o3 The PI closed-loop control is adopted to regulate the phase difference PHc of the closed-loop output, and it is sent to the third HH full-bridge module M3. The drive signal is distributed to the switching transistors S1 to S8 according to the phase difference PHc.

[0019] Furthermore, the DC inverter multiplexing high-frequency isolation converter is used for DC-AC isolation conversion;

[0020] The first input terminals of the multiple HH full-bridge modules are interconnected and provide external wiring to connect to the external DC positive terminal DC1; the second input terminals of the multiple HH full-bridge modules are interconnected and provide external wiring to connect to the external DC negative terminal DC2.

[0021] The first output terminals of the multiple HH full-bridge modules are interconnected and provide external wiring to connect to the external DC positive terminal DC1; the second output terminals of the multiple HH full-bridge modules are interconnected and provide external wiring to connect to the external DC negative terminal DC2.

[0022] Furthermore, given the output port voltage command V dcref The feedback is the output port voltage V. dc The system employs PI closed-loop control, outputting a phase difference PH, which is then sent to each HH full-bridge module. Drive signals are distributed to the switching transistors S1 to S8 according to the phase difference PH.

[0023] The advantages of the DC inverter multiplexing high-frequency isolation converter of the present invention are as follows:

[0024] The isolation converter provided by this invention employs different interface connection modes, enabling it to function as a DC-AC inverter or a DC-DC converter, with bidirectional energy flow, achieving DC-DC inverter-multiplexed high-frequency isolation conversion. This invention unifies AC and DC conversion within a single device, and during the DC-AC conversion process, it enables high-frequency isolation and soft switching, effectively improving the device's efficiency, power density, and versatility.

[0025] The isolation converter provided by this invention can be composed of any number of HH full-bridge modules, and each HH full-bridge module has a completely identical topology, thus having good versatility.

[0026] The input and output ports of the isolation converter provided by this invention can be configured as DC or AC ports as needed, which can easily realize the interconnection of DC and AC power grids;

[0027] The isolation conversion device provided by this invention uses high-frequency isolation to achieve electrical safety in power grid interconnection;

[0028] The topology of the isolation converter provided by this invention can achieve soft switching and improve conversion efficiency;

[0029] The isolation converter topology provided by this invention adopts high-frequency conversion, has a simple structure, and high power density. Attached Figure Description

[0030] Figure 1 This is the main circuit diagram of a DC inverter multiplexing high-frequency isolation converter connected in DC-AC mode, provided by the present invention.

[0031] Figure 2 This is a control block diagram of a DC inverter multiplexing high-frequency isolation converter.

[0032] Figure 3 This is a simulation waveform of a DC-AC mode for a DC inverter multiplexing high-frequency isolation converter.

[0033] Figure 4 It is the drive waveform of each switch in the DC-AC mode of the DC-AC inverter multiplexed high-frequency isolation converter. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0035] like Figure 1 As shown, this invention proposes a DC inverter multiplexing type high-frequency isolation converter. The DC inverter multiplexing type high-frequency isolation converter can be composed of two or three HH full-bridge modules. Two HH full-bridge modules can form a single-phase AC interface, and three HH full-bridge modules can form a three-phase AC interface.

[0036] Specifically, this invention provides a DC inverter multiplexing type high-frequency isolation converter, which includes two or three HH full-bridge modules. Each HH full-bridge module includes two DC capacitors C1 and C2, two H full-bridge capacitors Q1 and Q2, and one high-frequency isolation transformer T1. The first and second input terminals on the input side are connected to the DC capacitor C1, C1 is connected to the H full-bridge capacitor Q1, Q1 is connected to the primary side of the high-frequency isolation transformer T1, the secondary side of the high-frequency isolation transformer T1 is connected to the H full-bridge capacitor Q2, Q2 is connected to the DC capacitor C2, and C2 is connected to the first and second output terminals on the output side.

[0037] The H-bridge Q1 includes a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4; the H-bridge Q2 includes a fifth switch S5, a sixth switch S6, a seventh switch S7, and an eighth switch S8. The positive terminal of DC capacitor C1 is connected to the collectors of the first switch S1 and the third switch S3, and the negative terminal of DC capacitor C1 is connected to the emitters of the second switch S2 and the fourth switch S4. The emitter of the first switch S1 is connected to the collector of the second switch S2 and the upper end of the primary winding of the high-frequency isolation transformer T1, and the emitter of the third switch S3 is connected to the collector of the fourth switch S4 and the lower end of the primary winding of the high-frequency isolation transformer T1. The positive terminal of DC capacitor C2 is connected to the collectors of the fifth switch S5 and the seventh switch S7, and the negative terminal of DC capacitor C2 is connected to the emitters of the sixth switch S6 and the eighth switch S8. The emitter of the fifth switch S5 is connected to the collector of the sixth switch S6 and the lower end of the secondary winding of the high-frequency isolation transformer T1, and the emitter of the seventh switch S7 is connected to the collector of the eighth switch S8 and the upper end of the secondary winding of the high-frequency isolation transformer T1.

[0038] Specifically, multiple HH full-bridge modules can be combined to form DC or AC ports. Specifically, with three modules combined, the first input terminals of HH full-bridge module M1, HH full-bridge module M2, and HH full-bridge module M3 are interconnected. The second input terminals of HH full-bridge module M1, HH full-bridge module M2, and HH full-bridge module M3 are interconnected. External wiring is provided to the first input terminals of all modules for connection to an external DC positive terminal (DC1), and external wiring is provided to the second input terminals of all modules for connection to an external DC negative terminal (DC2). This forms a DC interface at the input terminals. Similarly, the output terminals can also be configured as DC interfaces in the same way. Likewise, two modules can be configured as DC interfaces using the same method.

[0039] The three modules are combined: the second output terminals of HH full-bridge module M1, HH full-bridge module M2, and HH full-bridge module M3 are interconnected but not connected to any external interface; the first output terminal of HH full-bridge module M1 is connected to external three-phase AC phase A, the first output terminal of HH full-bridge module M2 is connected to external three-phase AC phase B, and the first output terminal of HH full-bridge module M3 is connected to external three-phase AC phase C, thus forming a three-phase AC interface at the output terminals. Similarly, the input terminals can also be configured as DC interfaces in the same way. Likewise, two modules can be configured as a two-phase AC interface using the same method.

[0040] In particular, the input and output terminals of multiple HH full-bridge modules can be connected as DC or AC interfaces according to application needs. When both the input and output terminals are connected as DC interfaces, a DC-DC converter is formed. When the input terminal is connected as DC and the output terminal is connected as AC, a DC-AC inverter is formed. When the output terminal is connected as DC and the input terminal is connected as AC, an AC-DC rectifier is formed.

[0041] Furthermore, all HH full-bridge modules employ a phase-shift control strategy, and the switching transistors S1 to S8 have the same switching frequency and duty cycle. Typical drive waveforms for each switching transistor are shown below. Figure 4 As shown, S1 and S4 are turned on and off simultaneously, S2 and S3 are turned on and off simultaneously, and S2 is 180 degrees out of phase with S1; S5 and S8 are turned on and off simultaneously, and S6 and S7 are turned on and off simultaneously, and S5 is 180 degrees out of phase with S6; the phase difference between the drive signals of S1 and S5 is the phase difference result of the closed-loop control output.

[0042] When operating in DC-DC mode, the given output port voltage command V dcref The feedback is the output port voltage V. dc The system employs PI closed-loop control, outputting a phase difference PH, which is then sent to each HH full-bridge module. Drive signals are distributed to the switching transistors S1 to S8 according to the phase difference PH.

[0043] When operating in DC-AC mode, taking a three-phase AC interface as an example, the HH full-bridge module M1 provides the output port voltage command V. a +V d V a =M×Sin(w×t+pha), where is the target value of the phase A AC voltage, V d It is a DC bias value, and V d >M; Feedback is the voltage V across the second DC capacitor C2 of the HH full-bridge module M1. o1 The PI closed-loop control is adopted to regulate the phase difference PHA of the closed-loop output, and sends it to the HH full-bridge module M1. The drive signal is distributed to the switching transistors S1 to S8 according to the phase difference PHA.

[0044] Similarly, the HH full-bridge module M2 gives the output port voltage command V. b +V d V b =M×Sin(w×t+phb), where is the target value of the phase B AC voltage, V d It is a DC bias value, and V d >M; Feedback is the voltage V across the second DC capacitor C2 of the HH full-bridge module M2. o2 The PI closed-loop control is adopted to regulate the phase difference PHb output by the closed loop and send it to the HH full-bridge module M2. The drive signal is distributed to the switching transistors S1 to S8 according to the phase difference PHb.

[0045] Similarly, the HH full-bridge module M3 gives the output port voltage command V. c +V d V c =M×Sin(w×t+phc), where is the target value of the C-phase AC voltage, V d It is a DC bias value, and V d >M; Feedback is the voltage V across the second DC capacitor C2 of the HH full-bridge module M3. o3 The system employs PI closed-loop control, outputting a phase difference PHc, which is then sent to the HH full-bridge module M3. Drive signals are distributed to the switching transistors S1 to S8 according to the phase difference PHc. Similarly, the single-phase AC interface is controlled using the same method.

[0046] In one embodiment, the input DC voltage V in The voltage is DC 900V; the output voltage is three-phase AC 390V 50Hz; the transformer ratio is 1:1; all capacitors are 600uF; the switching frequency is f. s =15kHz. Figure 3 The figure shows the input and output voltage waveforms when the input voltage is 900VDC and the output voltage is three-phase AC390V 50Hz. Figure 4 It is the driving waveform of the switching transistors S1 to S8 in the DC-AC mode of the DC-AC inverter multiplexing high-frequency isolation converter.

Claims

1. A DC inverter-multiplexed high-frequency isolation converter, characterized in that, The direct-current inversion multiplexing high-frequency isolation conversion device includes two or three H-H full-bridge modules for DC-AC isolation conversion; Each H-H full-bridge module includes two direct-current capacitors C1 and C2, two H full-bridge Q1 and Q2, and one high-frequency isolation transformer T1; The first input end and the second input end of the input side are connected with the direct-current capacitor C1, the C1 is connected with the H full-bridge Q1, the Q1 is connected with the primary side of the high-frequency isolation transformer T1, the secondary side of the high-frequency isolation transformer T1 is connected with the H full-bridge Q2, the Q2 is connected with the direct-current capacitor C2, and the C2 is connected with the first output end and the second output end of the output side; The first input ends of the plurality of H-H full-bridge modules are connected with each other and are connected with the external direct-current positive electrode DC1 through external wiring; the second input ends of the plurality of H-H full-bridge modules are connected with each other and are connected with the external direct-current negative electrode DC2 through external wiring; The second output ends of the plurality of H-H full-bridge modules are connected with each other and do not provide output wiring; the first output ends of the H-H full-bridge modules are respectively used as two-phase or three-phase alternating current; The H full-bridge Q1 includes a first switch tube S1, a second switch tube S2, a third switch tube S3 and a fourth switch tube S4; the H full-bridge Q2 includes a fifth switch tube S5, a sixth switch tube S6, a seventh switch tube S7 and an eighth switch tube S8; the positive electrode of the direct-current capacitor C1 is connected with the collector of the first switch tube S1 and the third switch tube S3, the negative electrode of the direct-current capacitor C1 is connected with the emitter of the second switch tube S2 and the fourth switch tube S4, the emitter of the first switch tube S1 is connected with the collector of the second switch tube S2 and the upper end point of the primary side winding of the transformer T1, the emitter of the third switch tube S3 is connected with the collector of the fourth switch tube S4 and the lower end point of the primary side winding of the transformer T1, the positive electrode of the direct-current capacitor C2 is connected with the collector of the fifth switch tube S5 and the seventh switch tube S7, the negative electrode of the direct-current capacitor C2 is connected with the emitter of the sixth switch tube S6 and the eighth switch tube S8, the emitter of the fifth switch tube S5 is connected with the collector of the sixth switch tube S6 and the lower end point of the secondary side winding of the transformer T1, and the emitter of the seventh switch tube S7 is connected with the collector of the eighth switch tube S8 and the upper end point of the secondary side winding of the transformer T1; The direct-current inversion multiplexing high-frequency isolation conversion device is used for DC-AC isolation conversion; The first input ends of the plurality of H-H full-bridge modules are connected with each other and are connected with the external direct-current positive electrode DC1 through external wiring; the second input ends of the plurality of H-H full-bridge modules are connected with each other and are connected with the external direct-current negative electrode DC2 through external wiring; The first output ends of the plurality of H-H full-bridge modules are connected with each other and are connected with the external direct-current positive electrode DC1 through external wiring; the second output ends of the plurality of H-H full-bridge modules are connected with each other and are connected with the external direct-current negative electrode DC2 through external wiring.

2. The high-frequency isolation conversion device according to claim 1, wherein The H-H full-bridge modules all adopt a phase shift control strategy, the switch tubes S1-S8 have the same switching frequency and duty cycle, and a phase difference PH is generated between the driving signals of S1-S4 and S5-S8 according to the actual port voltage.

3. The high-frequency isolation conversion device according to claim 2, wherein The shown high-frequency isolation conversion device of direct-current inversion multiplex type comprises three H-H full-bridge modules. The first H-H full-bridge module M1 gives an output port voltage instruction V a +V d , wherein V a =M×Sin(w×t+pha), M is a phase voltage amplitude, w is a phase voltage frequency, and pha is a phase voltage phase; V a is an A-phase AC voltage target value, V d is a DC bias, and V d >M. The feedback is the voltage V across the second DC capacitor C2 of the first H-H full-bridge module M1 o1 The PI closed-loop control is adopted to adjust the closed-loop output phase difference PHa, which is sent to the first H-H full-bridge module M1, and the driving signals are distributed to the switch tubes S1-S8 according to the phase difference PHa. The second H-H full-bridge module M2 gives an output port voltage instruction V b +V d wherein V b =M x Sin(w x t + phb), is a B-phase AC voltage target value, V d is a DC bias quantity, and V d > M; The feedback is the voltage V across the second DC capacitor C2 of the H-H full-bridge module M2 o2 The PI closed-loop control is adopted to adjust the closed-loop output phase difference PHb, which is sent to the second H-H full-bridge module M2, and the driving signals are distributed to the switch tubes S1-S8 according to the phase difference PHb. The third H-H full-bridge module M3 gives an output port voltage instruction V c +V d , wherein V c =M×Sin(w×t+phc), the C-phase AC voltage target value, V d is a DC bias, and V d >M; The feedback is the voltage V across the second DC capacitor C2 of the H-H full-bridge module M3 o3 The PI closed-loop control is adopted to adjust the closed-loop output phase difference PHc, which is sent to the third H-H full-bridge module M3 to distribute the driving signals to the switch tubes S1-S8 according to the phase difference PHc.

4. The high-frequency isolation conversion device according to claim 1, wherein Given output port voltage command V dcref , feedback is output port voltage V dc , PI closed loop control is adopted to adjust the closed loop output phase difference PH, and is sent to each H-H full bridge module, and the driving signals are distributed to the switch tubes S1-S8 according to the phase difference PH.

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