A high-gain DC-AC inverter with staggered parallel connection for photovoltaic hydrogen production

Abstract

The present invention discloses a staggered parallel high-gain DC-AC inverter for photovoltaic hydrogen production, comprising a first transformer, a second transformer, a staggered parallel circuit, a dual three-port asymmetric boost circuit and an inverter circuit, wherein the primary coil L1 of the first transformer and the primary coil L3 of the second transformer are connected in parallel, and the secondary coil L2 of the first transformer and the secondary coil L4 of the second transformer are connected in series; the staggered parallel circuit is used to convert the photovoltaic power source V in The dual three-port asymmetric boost circuit is used to boost the voltage output by the secondary coils of the first transformer and the second transformer, and output asymmetric bipolar direct current; the inverter circuit is used to convert the direct current output by the dual three-port asymmetric boost circuit into alternating current, and then output it to the hydrogen production grid V g The present invention has high conversion efficiency and small voltage fluctuation.

Description

Technical Field

[0001] The invention relates to an inverter, and in particular to an interleaved parallel high-gain DC-AC inverter for photovoltaic hydrogen production. Background Art

[0002] As energy crisis and environmental pollution become increasingly serious, new energy power generation technologies such as solar energy have become a hot topic of research. However, the quality of new energy power is poor and has strong randomness. Therefore, the use of new energy to produce hydrogen has become an important means of absorbing new energy. The application of photovoltaic hydrogen production technology is becoming more and more extensive, and how to improve the efficiency and stability of the inverter has become a key challenge. Usually, the photovoltaic voltage is raised to the high-voltage bus voltage required for grid connection, and then converted into alternating current by the inverter, which is transmitted to the hydrogen production plant through the transmission line to reduce transmission losses. Therefore, it is crucial to match the photovoltaic voltage with the grid-connected inverter.

[0003] The instability of the output current of the photovoltaic system may have an adverse effect on the photovoltaic hydrogen production electrolyzer. When considering the topology of the photovoltaic inverter, it is necessary not only to realize the basic boost function, but also to consider the overall conversion efficiency of the system and safe and reliable operation. Among them, safe and reliable operation is easily overlooked during the design process, especially after the photovoltaic components are installed and fixed, they will generate parasitic capacitance with the ground. When the photovoltaic system starts working, the parasitic capacitance will form a loop with the subsequent circuit, thereby generating common-mode current. When the parasitic capacitance is large, the common-mode current generated is also large. This situation may have a greater impact on the inverter circuit and even damage the circuit. Existing inverters are basically two-level DC converters. Some inverters use staggered Flyback + full-bridge power frequency flip topology to realize energy transfer to the grid. The full-bridge inverter has a large number of switch tubes, high cost, and the bus capacitor is a DC two-level structure. In addition, when the capacitor capacity of each module in the inverter is different and the inductor parameters of each module in the inverter are different, the bus voltage will be unbalanced. The bus voltage imbalance causes voltage fluctuations, and the inverter bus capacitor voltage ripple is large, resulting in a short inverter life. Some inverters are based on a single-phase full-bridge inverter topology with a symmetrical inductor configuration. This topology can eliminate common-mode leakage current by applying bipolar modulation, but it has the disadvantages of large harmonics and low conversion efficiency; and although unipolar modulation reduces the requirements for filters and has higher conversion efficiency, it has leakage current problems. It can be seen from this that the single-phase full-bridge inverter topology with a symmetrical inductor configuration, whether it is bipolar modulation or unipolar modulation, cannot meet the overall needs of practical applications. In summary, the existing inverters have the disadvantages of difficult voltage fluctuations and low conversion efficiency, which leads to limited hydrogen production efficiency. Summary of the invention

[0004] In view of the problems existing in the prior art, the purpose of the present invention is to provide a staggered parallel high-gain DC-AC inverter for photovoltaic hydrogen production with high conversion efficiency and small voltage fluctuation.

[0005] In order to achieve the above-mentioned purpose of the invention, the present invention provides a staggered parallel high-gain DC-AC inverter for photovoltaic hydrogen production, comprising:

[0006] A first transformer and a second transformer, wherein the primary coil L of the first transformer 1 and the primary coil L of the second transformer 3 In parallel, the secondary coils are connected in series;

[0007] The staggered parallel circuit is used to connect the photovoltaic power source to the primary coil L of the first transformer 1 and the primary coil L of the second transformer 3 Staggered parallel connection;

[0008] A dual three-port asymmetric boost circuit is used to boost the voltage output by the secondary coils of the first transformer and the second transformer to output asymmetric bipolar direct current, including a first capacitor C 1 , the second capacitor C 2 , the third capacitor C 3 , the fourth capacitor C 4 , the fifth capacitor C 5 , the seventh capacitor C 7 、The eighth capacitor C 8 , the first diode D 1 , the second diode D 2 , the third diode D 3 , the fourth diode D 4 , the fifth diode D 5 , the eighth diode D 8 , where the secondary coil L of the first transformer 2 and the secondary coil L of the second transformer 4 The first ends of the series connection are respectively connected to the second capacitor C 2 , the third capacitor C 3 , the fourth capacitor C 4 The first end of the series connection is connected to the first capacitor C 1 , the fifth capacitor C 5 , the seventh capacitor C 7 、The eighth capacitor C 8 The first end of the third diode D 3 The cathode of the fifth diode D 5 The positive electrode of the second capacitor C 2 The second end of the second diode D 2 The anode of the second diode D 2 The cathode of each diode D1 The positive electrode and the first capacitor C 1 The second end of the first diode D 1 The negative electrodes are connected to the third capacitor C 3 The second end and the third diode D 3 The positive electrode of the fourth capacitor C 4 The second ends of the fourth diodes D 4 The anode of the fifth diode D 5 The cathode of the fourth diode D 4 The cathode of each diode D 8 The positive electrode and the fifth capacitor C 5 The second end of the eighth diode D 8 The negative electrode of the seventh capacitor C 7 The second end of the eighth capacitor C 8 The second end is connected to the negative pole of the photovoltaic power source;

[0009] The inverter circuit is used to convert the direct current output by the dual three-port asymmetric boost circuit into alternating current and then output it to the hydrogen production grid.

[0010] Furthermore, the interleaved parallel circuit includes a first switch tube S 1 and the second switch tube S 2 , the first switch tube S 1 The drain of the first transformer is connected to the primary coil L 1 The first end of the switch tube S 2 The drain of the second transformer is connected to the primary coil L 3 The first end of the primary coil of the first transformer and the second transformer are connected to the positive electrode of the photovoltaic power supply.

[0011] Furthermore, the staggered parallel circuit also includes a clamping circuit, and the clamping circuit includes a sixth diode D 6 , the seventh diode D 7 and the sixth capacitor C 6 , the sixth diode D 6 The positive pole is connected to the primary coil L of the first transformer 1 The first end and the cathode are connected to the second diode D 2 The positive electrode and the sixth capacitor C 6 The first end of the seventh diode D 7 The positive pole is connected to the primary coil L of the second transformer 3 The first end and the cathode are connected to the second diode D 2 The positive electrode and the sixth capacitor C 6 The first end of the sixth capacitor C 6The second end is connected to the negative pole of the photovoltaic power source.

[0012] Furthermore, the inverter circuit includes a third switch tube T 1 , the fourth switch tube T 2 and filter inductor L f , the third switch tube T 1 The drain of the eighth diode D 8 The negative electrode of the third switch tube T 1 The source of the fourth switch tube T 2 The drain of the third switch tube T 1 The source of the filter is also connected through the filter inductor L f One end connected to the hydrogen production grid, the fourth switch tube T 2 The source electrode is connected to the negative electrode of the photovoltaic power source, and the other end of the hydrogen production grid is connected to the seventh capacitor C 7 The first end.

[0013] Furthermore, the first switch tube S 1 The gate inputs the first PWM control wave signal, and the second switch tube S 2 The gate of the first switch tube S is input with a second PWM control wave signal, and the first PWM control wave signal is used to control the first switch tube S 1 The second PWM control wave signal is used to control the second switch tube S 2 The third switch tube T 1 The gate of the fourth switch tube T is input with the third PWM control wave signal. 2 The gate of the third switch tube T is input with a fourth PWM control wave signal, and the third PWM control wave signal is used to control the third switch tube T 1 The fourth PWM control wave signal is used to control the fourth switch tube T 2 The duty cycle of the first PWM control wave signal and the second PWM control wave signal are both 0.6.

[0014] Furthermore, the primary coil L of the first transformer 1 and the secondary coil L 2 The turns ratio is 1, and the primary coil L of the second transformer 3 and the secondary coil L 3 The turns ratio is 1.

[0015] Furthermore, the first switch tube S 1 , the second switch tube S 2 The third switch tube T 1 , the fourth switch tube T 2 Both are NMOS tubes.

[0016] Compared with the prior art, the present invention has the following beneficial effects: the input part of the present invention adopts a staggered parallel structure, which can better adapt to the occasion of low voltage and high current input. The present invention has five boost circuits, among which when S 1 On, S 2 When turned off, three boost units are charged and the other two boost units are discharged at the same time. 2 When S1 is turned on and S2 is turned off, two boost units are charged and the other three boost units are discharged at the same time. The two cooperate with each other to control their respective boost units, which has high power conversion efficiency and high gain. The staggered parallel structure can evenly distribute the two-phase power, with small single-phase power, small current and small inductance, which is suitable for high power and small input current ripple; the dual three-port asymmetric boost circuit improves the voltage gain and realizes asymmetric bipolarity for the inverter. Through the output capacitor C 8 The leakage current is suppressed and the device voltage stress is small. The voltage difference between the two output capacitors is small and constant, and the voltage difference is independent of the turns ratio, which is conducive to the suppression of leakage current. The secondary coils are connected in series to offset the influence of parasitic parameters. The present invention can effectively expand the input voltage range and reduce current fluctuations, thereby improving the overall performance of the system and ensuring the efficiency and stability of the photovoltaic hydrogen production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 An electrical schematic diagram of an interleaved parallel high-gain DC-AC inverter for photovoltaic hydrogen production provided by an embodiment of the present invention;

[0018] Figure 2 is an electrical schematic diagram of an interleaved parallel circuit in an embodiment of the present invention;

[0019] Figure 3 1 is an electrical schematic diagram of a dual three-port asymmetric boost circuit according to an embodiment of the present invention;

[0020] Figure 4 This is an electrical schematic diagram of an embodiment of the present invention when working in mode 1;

[0021] Figure 5 This is an electrical schematic diagram of an embodiment of the present invention when working in mode 2;

[0022] Figure 6 This is an electrical schematic diagram of an embodiment of the present invention when working in mode 3;

[0023] Figure 7 This is an electrical schematic diagram of an embodiment of the present invention when working in mode 4;

[0024] Figure 8 This is an electrical schematic diagram of an embodiment of the present invention when working in mode 5;

[0025] Fig. 9This is an electrical schematic diagram of an embodiment of the present invention when working in mode 6. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0027] The invention provides a high-gain DC-AC inverter for photovoltaic hydrogen production, such as Figure 1 As shown, it includes a first transformer, a second transformer, an interleaved parallel circuit, a dual three-port asymmetric boost circuit and an inverter circuit. The primary coil L of the first transformer 1 and the primary coil L of the second transformer 3 In parallel, the secondary coil L of the first transformer 2 and the secondary coil L of the second transformer 4 The series; staggered parallel circuit includes a first switch tube S 1 and the second switch tube S 2 , used to convert the photovoltaic power source V in The primary coil L of the first transformer 1 and the primary coil L of the second transformer 3 Staggered parallel connection; the dual three-port asymmetric boost circuit includes a first capacitor C 1 , the second capacitor C 2 , the third capacitor C 3 , the fourth capacitor C 4 , the fifth capacitor C 5 , the seventh capacitor C 7 、The eighth capacitor C 8 , the first diode D 1 , the second diode D 2 , the third diode D 3 , the fourth diode D 4 , the fifth diode D 5 , the eighth diode D 8 , used to boost the voltage output by the secondary coils of the first transformer and the second transformer to output asymmetric bipolar direct current; the inverter circuit includes a third switch tube T 1 , the fourth switch tube T 2 and filter inductor L f , used to convert the DC power output by the dual three-port asymmetric boost circuit into AC power and output it to the hydrogen production grid V g .

[0028] like Figure 1 and Figure 2 As shown, in the staggered parallel circuit, the first switch tube S 1 The drain of the first transformer is connected to the primary coil L 1The first end of the switch tube S 2 The drain of the second transformer is connected to the primary coil L 3 The first end of the source is connected to the negative pole of the photovoltaic power source, and the primary coil L of the first transformer 1 , the primary coil L of the second transformer 3 The second ends are connected to the positive electrode of the photovoltaic power source.

[0029] In addition, in order to obtain a better effect, the staggered parallel circuit may further include a clamping circuit, the clamping circuit including a sixth diode D 6 , the seventh diode D 7 and the sixth capacitor C 6 , the sixth diode D 6 The positive pole is connected to the primary coil L of the first transformer 1 The first end and the cathode are connected to the second diode D 2 The positive electrode and the sixth capacitor C 6 The first end of the seventh diode D 7 The positive pole is connected to the primary coil L of the second transformer 3 The first end and the cathode are connected to the second diode D 2 The positive electrode and the sixth capacitor C 6 The first end of the sixth capacitor C 6 The second end of the sixth diode D is connected to the negative electrode of the photovoltaic power source. 6 The negative electrode is used as the first output terminal P of the staggered parallel circuit 1 , the seventh diode D 7 The negative electrode is used as the second output terminal P of the staggered parallel circuit 2 , the negative pole of the photovoltaic power source is used as the third output terminal P of the staggered parallel circuit 3 .

[0030] like Figure 1 and Figure 3 As shown, the dual three-port asymmetric boost circuit includes a first capacitor C 1 , the second capacitor C 2 , the third capacitor C 3 , the fourth capacitor C 4 , the fifth capacitor C 5 , the seventh capacitor C 7 、The eighth capacitor C 8 , the first diode D 1 , the second diode D 2 , the third diode D 3 , the fourth diode D 4 , the fifth diode D 5 , the eighth diode D 8 , where the secondary coil L of the first transformer 2and the secondary coil L of the second transformer 4 The first ends of the series connection are respectively connected to the second capacitor C 2 , the third capacitor C 3 , the fourth capacitor C 4 The first end of the series connection is connected to the first capacitor C 1 , the fifth capacitor C 5 , the seventh capacitor C 7 、The eighth capacitor C 8 The first end of the third diode D 3 The cathode of the fifth diode D 5 The positive electrode of the second capacitor C 2 The second end of the second diode D 2 The anode of the second diode D 2 The cathode of each diode D 1 The positive electrode and the first capacitor C 1 The second end of the first diode D 1 The negative electrodes are connected to the third capacitor C 3 The second end and the third diode D 3 The positive electrode of the fourth capacitor C 4 The second ends of the fourth diodes D 4 The anode of the fifth diode D 5 The cathode of the fourth diode D 4 The cathode of each diode D 8 The positive electrode and the fifth capacitor C 5 The second end of the eighth diode D 8 The negative electrode of the seventh capacitor C 7 The second end of the eighth capacitor C 8 The second end of the second capacitor C is connected to the negative electrode of the photovoltaic power source. 2 The second end is used as the input terminal P 4 , and P 1 Connect the second diode D 2 The positive terminal is used as the input terminal P 5 , and P 2 Connect the eighth capacitor C 8 The second end is used as the input terminal P 6 , and P 3 Connect the eighth diode D 8 The negative pole is used as the output terminal P 7 , the eighth capacitor C 8 The first end is used as the output terminal P 8 , the eighth capacitor C 8 The second end is used as the output terminal P 9 .

[0031] like Figure 1As shown, the inverter circuit includes a third switch tube T 1 , the fourth switch tube T 2 and filter inductor L f , the third switch tube T 1 The drain of the eighth diode D 8 The negative pole, that is, the output terminal P 7 , the third switch tube T 1 The source of the fourth switch tube T 2 The drain of the third switch tube T 1 The source of the filter is also connected through the filter inductor L f One end connected to the hydrogen production grid, the fourth switch tube T 2 The source of the photovoltaic power source is connected to the negative pole, that is, the output terminal P 9 The other end of the hydrogen production grid is connected to the eighth capacitor C 8 The first end, that is, the output end P 8 .

[0032] Among them, the first switch tube S 1 The gate inputs the first PWM control wave signal, and the second switch tube S 2 The gate of the third switch tube T is input with the second PWM control wave signal. 1 The gate of the fourth switch tube T inputs the third PWM control wave signal, 2 The gate of the switch tube S is input with the fourth PWM control wave signal. The four PWM control wave signals are input through an external drive circuit and are used to control the switching of the corresponding switch tube, and the duty ratio of the first PWM control wave signal and the second PWM control wave signal is 0.6. In the topology of the conventional converter, the switch tube S 1 And switch tube S 2 The duty cycle D of the PWM control wave signal has an operating range of 0.5-1, and the voltage gain is low when the duty cycle D is slightly greater than 0.5. 1 and S 2 The duty cycle D of the PWM control wave signal has an operating range of 0-1 and has high gain in the full range. Compared with the conventional topology, it broadens the operating range of the duty cycle D and can effectively improve the voltage gain. 1 and S 2 When the duty cycle is 0.6 and the two pulses maintain a certain phase difference, at least one switch tube in the circuit can always be kept in the on state.

[0033] The first switch tube S 1 , the second switch tube S 2 All are NMOS tubes. The third switch tube T 1 , the fourth switch tube T 2 Both are NMOS tubes.

[0034] In addition, the primary coil L of the first transformer 1 and the secondary coil L 2 The turns ratio is 1, and the primary coil L of the second transformer 3 and the secondary coil L 3 The turns ratio is 1.

[0035] When S 1 On, S 2 When off, D 3 , C 3 , L 2 , L 4 It forms a boost unit, D 4 , C 4 , C 5 , L 2 , L 4 It forms a boost unit, D 2 , C 1 , C 2 , L 2 , L 4 It forms a boost unit; when S 2 On, S 1 When off, D 1 , C 1 , C 3 , L 2 , L 4 It forms a boost unit, D 5 , C 4 , L 2 , L 4 It constitutes a boost unit.

[0036] Working principle of the present invention: In the working mode, it is divided into 6 modes, as follows:

[0037] like Figure 4 As shown, mode 1[t 0 -t 1 ]:When t 0 When S 1 On, S 2 Disconnect. Diode D 7 , D 2 , D 3 , D 4 Turn on, diode D 6 , D 1 , D 5 , D 8 Reverse cutoff. L 3 and L 4 The energy in the leakage inductance flows to C 6 As the leakage inductance energy decreases, D 7The current gradually decreases. L 2 and L 4 By D 3 C 3 to charge, and with C 4 Together through D 4 C 5 For charging, also with C 1 Together through D 2 C 2 Charge. 7 and C 8 For hydrogen production grid V g Power supply. When t 1 Moment, S 2 When the activation signal comes, the first mode ends.

[0038] like Figure 5 As shown, mode 2[t 1 -t 2 ]:t 1 Moment, S 2 conduction, due to the L on the secondary side 2 and L 4 The coupling direction is opposite, L 2 and L 4 The voltages of the two electrodes cancel each other out and the current is in the continuous flow state, and the current begins to decrease gradually. 2 Moment, L 2 and L 4 When the current continues to flow, the second mode ends.

[0039] like Figure 6 As shown, mode 3[t 2 -t 3 ]:t 2 Moment, L 2 and L 4 The freewheeling ends, and the diode D 2 , D 3 , D 4 Natural shutdown. S 1 and S 2 Keep conducting. In this mode, all diodes are cut off due to reverse voltage. In this mode, C 7 and C 8 Continue to supply power to the load. 3 Moment, S 1 When the shutdown signal comes, the third mode ends.

[0040] like Figure 7 As shown, mode 4[t 3 -t 4 ]:t 3 Moment, S 1 Shutdown, S2 Keep the diode D 7 , D 2 , D 3 , D 4 Withstand reverse voltage cutoff. D 6 On, C 6 Energy increase. 2 and L 4 By D 5 C 4 Charging, and with C 3 Together through D 1 C 1 Charging, also with C 2 With C 5 By D 8 Power the hydrogen production grid. 4 Moment, S 1 When the activation signal comes, the fourth mode ends.

[0041] like Figure 8 As shown, mode 5[t 4 -t 5 ]:t 4 Moment, S 1 conduction, due to L 2 and L 4 The coupling direction is opposite, L 2 and L 4 The voltages of the two electrodes cancel each other out and the current is in the continuous flow state, and the current begins to decrease gradually. 5 Moment, L 2 and L 4 When the current continues to flow, the fifth mode ends.

[0042] like Fig. 9 As shown, mode 6[t 5 -t 6 ]:t 5 Moment, L 2 and L 4 The freewheeling ends, and the diode D 1 , D 5 , D 8 Natural shutdown. S 1 and S 2 Keep conducting. In this mode, all diodes are cut off due to reverse voltage. In this mode, C 7 and C 8 Continue to supply power to the load. 6 Moment, S 2 When the shutdown signal comes, the sixth mode ends.

[0043] In all modal analyses, because the T 1 and T2 The frequency of S 1 and S 2 The frequency is much lower, so T 1 and T 2 The switching state of T remains unchanged for a long time and has no effect on the circuit. Therefore, T is not analyzed in the above modes. 1 and T 2 The switch status.

[0044] Based on the modal analysis, the expression of the voltage gain of the inverter is further derived.

[0045] Sixth capacitor C 6 The voltage of is equal to the output voltage of the Boost converter. C 6 Voltage for:

[0046] ,

[0047] Where V in is the photovoltaic power supply voltage, D is S 1 duty cycle.

[0048] During Mode 1, S 1 In open state, S 2 In the off state.

[0049] ,

[0050] ,

[0051] In the formula, They are respectively L 1 , L 2 , L 3 , L 4 Voltage, N 1 、N 2 are the coil turns ratios of the first transformer and the second transformer respectively, and K is the coupling coefficient between the primary coil and the secondary coil. In this embodiment, the coupling coefficients of the two transformers are the same, which is K.

[0052] During Mode 1, the capacitor C 1 , C 2 , C 3 , C 4 , C5 And the secondary coil L 2 and L 4 Writing Kirchhoff's voltage law expression, we can get the capacitance C 2 , C 3 The voltage and capacitance C 5 The voltage expression is as follows:

[0053] ,

[0054] ,

[0055] ,

[0056] In the formula, They are C 1 , C 2 , C 3 , C 4 , C 5 voltage.

[0057] During Mode 2, the capacitor C 1 , C 6 , C 8 Writing Kirchhoff's voltage law expression, we can get C 8 Voltage as follows:

[0058] .

[0059] During Mode 4, S 2 In open state, S 1 In the off state, L 2 and L 4 The voltages are as follows:

[0060] ,

[0061] In the formula, They represent L during mode 4 respectively. 1 , L 2 , L 3, L 4 voltage.

[0062] During Mode 4, the capacitor C 1 , C 2 , C 3 , C 4 , C 5 , C 7 as well as L 2 and L 4 Writing Kirchhoff's voltage law expression, we can get the capacitance C 1 , C 4 The voltage and capacitance C 7 The voltage expression is as follows:

[0063] ,

[0064] In the formula, express C 7 voltage.

[0065] Combining the above expressions, we can get the capacitance C 7 , C 8 The voltage expression is:

[0066] .

[0067] During Mode 6, the capacitor C 7 , C 8 The expression of Kirchhoff's voltage law for the hydrogen production grid is obtained by:

[0068] .

[0069] The inverter voltage gain M expression is:

[0070] .

[0071] It can be seen from the above formula that the inverter of the present application can achieve high voltage gain under the condition of extreme duty cycle. As the turns ratio N increases, the voltage gain of the inverter will be greatly improved.

[0072] When analyzing the voltage stress between semiconductor devices of the inverter of this application, it is considered that N 1 =N 2 =N, and K= 1. According to the analysis, S 1 , S 2 Voltage stress Both C 6 The voltages are equal, as shown below:

[0073] .

[0074] When the turns ratio N is greater than 1, S 1 , S 2 Voltage stress The absolute value is lower than 1 / 5 of the output voltage. Therefore, the inverter can select a switching device with a lower rated voltage, which usually has a lower on-state resistance. R DS(ON) .

[0075] exist D 1 and D 3 When they are in the off state, D 1 , D 3 The voltage stress, Equal, the expression is:

[0076] .

[0077] exist D 6 and D 7 When they are in the off state, D 6 and D 7 Voltage stress Equal, the expression is:

[0078] .

[0079] exist D 4 , D 5 When the diode is in the off state, D 4 , D 5 Voltage stress Equal, the expression is:

[0080] .

[0081] From the voltage stress analysis of semiconductor devices, it can be seen that the highest voltage stress of the diode in the inverter of the present application is still much lower than the output voltage. The inverter of the present application has the advantage of low voltage stress of semiconductor devices.

[0082] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Unless otherwise clearly specified and limited, "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0083] It should be understood that the above embodiments and descriptions only describe the principles, main features and advantages of the present invention. Without departing from the spirit and scope of the present invention, the present invention may be subject to various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. A high-gain DC-AC inverter for photovoltaic hydrogen production, characterized in that: include: A first transformer and a second transformer, wherein the primary coil L1 of the first transformer and the primary coil L3 of the second transformer are connected in parallel, and the secondary coil L2 of the first transformer and the secondary coil L4 of the second transformer are connected in series; An interlaced parallel circuit is used to connect the photovoltaic power supply to the primary coil L1 of the first transformer and the primary coil L3 of the second transformer in an interlaced parallel manner respectively; the interlaced parallel circuit includes a first switch tube S1 and a second switch tube S2, the drain of the first switch tube S1 is connected to the first end of the primary coil L1 of the first transformer, and the source is connected to the negative electrode of the photovoltaic power supply, the drain of the second switch tube S2 is connected to the first end of the primary coil L3 of the second transformer, and the source is connected to the negative electrode of the photovoltaic power supply, and the second ends of the primary coil L1 of the first transformer and the primary coil L3 of the second transformer are both connected to The positive electrode of the photovoltaic power supply; the staggered parallel circuit also includes a clamping circuit, which includes a sixth diode D6, a seventh diode D7 and a sixth capacitor C6, the positive electrode of the sixth diode D6 is connected to the first end of the primary coil L1 of the first transformer, and the negative electrode is respectively connected to the positive electrode of the second diode D2 and the first end of the sixth capacitor C6, the positive electrode of the seventh diode D7 is connected to the first end of the primary coil L3 of the second transformer, and the negative electrode is respectively connected to the positive electrode of the second diode D2 and the first end of the sixth capacitor C6, and the second end of the sixth capacitor C6 is connected to the negative electrode of the photovoltaic power supply; A dual three-port asymmetric boost circuit is used to boost the voltage output by the secondary coils of the first transformer and the second transformer to output asymmetric bipolar direct current, including a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a seventh capacitor C7, an eighth capacitor C8, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, and an eighth diode D8, wherein the first ends of the secondary coil L2 of the first transformer and the secondary coil L4 of the second transformer connected in series are respectively connected to the first ends of the second capacitor C2, the third capacitor C3, and the fourth capacitor C4, and the second ends of the series connection are respectively connected to the first capacitor C1, the fifth capacitor C5, the seventh capacitor C7, The first end of the eighth capacitor C8 is also connected to the cathode of the third diode D3 and the anode of the fifth diode D5, respectively; the second end of the second capacitor C2 is connected to the anode of the second diode D2; the cathode of the second diode D2 is connected to the anode of the first diode D1 and the second end of the first capacitor C1, respectively; the cathode of the first diode D1 is connected to the second end of the third capacitor C3 and the anode of the third diode D3, respectively; the second end of the fourth capacitor C4 is connected to the anode of the fourth diode D4 and the cathode of the fifth diode D5, respectively; the cathode of the fourth diode D4 is connected to the anode of the eighth diode D8 and the second end of the fifth capacitor C5, respectively; the cathode of the eighth diode D8 is connected to the second end of the seventh capacitor C7; and the second end of the eighth capacitor C8 is connected to the negative electrode of the photovoltaic power source; The inverter circuit is used to convert the direct current output by the dual three-port asymmetric boost circuit into alternating current and then output it to the hydrogen production grid.

2. The interleaved parallel high-gain DC-AC inverter for photovoltaic hydrogen production according to claim 1 is characterized in that: The inverter circuit includes a third switch tube T1, a fourth switch tube T2 and a filter inductor L f The drain of the third switch tube T1 is connected to the cathode of the eighth diode D8, the source of the third switch tube T1 is connected to the drain of the fourth switch tube T2, and the source of the third switch tube T1 is also connected to the cathode of the eighth diode D8 through the filtering inductor L f One end of the hydrogen production grid is connected, the source of the fourth switch tube T2 is connected to the negative electrode of the photovoltaic power supply, and the other end of the hydrogen production grid is connected to the first end of the seventh capacitor C7.

3. The interleaved parallel high-gain DC-AC inverter for photovoltaic hydrogen production according to claim 1, characterized in that: The gate of the first switch tube S1 inputs a first PWM control wave signal, and the gate of the second switch tube S2 inputs a second PWM control wave signal. The first PWM control wave signal is used to control the switching of the first switch tube S1, and the second PWM control wave signal is used to control the switching of the second switch tube S2.

4. The interleaved parallel high-gain DC-AC inverter for photovoltaic hydrogen production according to claim 2, characterized in that: The gate of the third switch tube T1 inputs a third PWM control wave signal, the gate of the fourth switch tube T2 inputs a fourth PWM control wave signal, the third PWM control wave signal is used to control the switching of the third switch tube T1, and the fourth PWM control wave signal is used to control the switching of the fourth switch tube T2.

5. The interleaved parallel high-gain DC-AC inverter for photovoltaic hydrogen production according to claim 3, characterized in that: The duty cycle of the first PWM control wave signal and the second PWM control wave signal are both 0.

6.

6. The interleaved parallel high-gain DC-AC inverter for photovoltaic hydrogen production according to claim 1, characterized in that: The turns ratio between the primary coil L1 and the secondary coil L2 of the first transformer is 1, and the turns ratio between the primary coil L3 and the secondary coil L3 of the second transformer is 1.

7. The interleaved parallel high-gain DC-AC inverter for photovoltaic hydrogen production according to claim 1, characterized in that: The first switch tube S1 and the second switch tube S2 are both NMOS tubes.

8. The interleaved parallel high-gain DC-AC inverter for photovoltaic hydrogen production according to claim 2, characterized in that: The third switch tube T1 and the fourth switch tube T2 are both NMOS tubes.

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