CN108023497B - Series simultaneous power supply forward cycle conversion type single-stage multi-input high-frequency link inverter - Google Patents

Abstract

The invention relates to a series-connected simultaneous power supply forward excitation cycle-transformed single-stage multi-input high-frequency link inverter. The input filter with common ground is connected with a common output high-frequency isolation transformer and cycle-wave transform filter circuit, and each input end of the multi-input single-output high-frequency inverter circuit is connected with the output end of each input filter in one-to-one correspondence , the output end of the multi-input single-output high-frequency inverter circuit is connected with the input end of the output high-frequency isolation transformer cycle-wave transform filter circuit; Isolation, shared output high-frequency transformer cycle transform filter circuit, simple circuit, single-stage power conversion, high conversion efficiency, small output voltage ripple, wide application prospects, etc. The power supply system has laid the key technology.

Description

Series Simultaneous Power Supply Forward Cycle-Converted Single-Stage Multi-Input High-Frequency Link Inverter

technical field

The invention relates to a series-connected simultaneous power supply forward cycle-transformed single-stage multi-input high-frequency link inverter, which belongs to the power electronic conversion technology.

Background technique

The inverter is a static converter device that uses power semiconductor devices to convert an unstable and inferior DC power into stable, high-quality AC power for use by AC loads or to achieve AC grid connection. Inverters with low-frequency electrical isolation (including no electrical isolation) or high-frequency electrical isolation between the output AC load or AC power grid and the input DC power supply are called low-frequency link and high-frequency link inverters respectively. The electrical isolation element mainly plays the following roles in the inverter: (1) realizes the electrical isolation between the output and input of the inverter, and improves the safety, reliability and electromagnetic compatibility of the inverter operation; (2) realizes the The matching between the output voltage of the inverter and the input voltage is achieved, that is, the technical effect that the output voltage of the inverter is higher than, equal to or lower than the input voltage is realized, and its application range has been greatly broadened; (3) When the high-frequency transformer When the working frequency of the high-frequency energy storage transformer is above 20kHz, its volume and weight are greatly reduced, and the audio noise is also eliminated. Therefore, the inverter has important application value in secondary electric energy conversion occasions with DC generators, batteries, photovoltaic cells and fuel cells as the main DC power sources.

New energy (also called green energy) such as solar energy, wind energy, tidal energy and geothermal energy has the advantages of clean, non-polluting, cheap, reliable and abundant, so it has a wide range of application prospects. Due to the increasing tension of traditional fossil energy (non-renewable energy) such as oil, coal and natural gas, serious environmental pollution, global warming, and the production of nuclear energy will produce nuclear waste and pollute the environment, the development and utilization of new energy is increasingly more and more attention. New energy power generation mainly includes photovoltaics, wind power, fuel cells, hydropower, geothermal and other types, all of which have shortcomings such as unstable, discontinuous, and climatic changes in power supply.

The traditional new energy distributed power supply system is shown in Figures 1 and 2. The system usually uses multiple single-input DC converters to convert photovoltaic cells, fuel cells, wind turbines, and other new energy power generation equipment that do not require energy storage through a one-way DC converter respectively. It is then connected to the DC bus of the public inverter to ensure that various new energy sources are jointly supplied and can work in harmony. The distributed generation system realizes the simultaneous supply of power to the load and the preferential utilization of energy from multiple input sources, which improves the stability and flexibility of the system, but has the defects of two-stage power conversion, low power density, low conversion efficiency, and high cost. Its usefulness is greatly limited.

In order to simplify the circuit structure and reduce the number of power conversion stages, it is necessary to replace the two-stage cascaded circuit structure with a DC converter and an inverter shown in Figures 1 and 2 with a new multi-input inverter with a single-stage circuit structure shown in Figure 3 The traditional multi-input inverter constitutes a new single-stage new energy distributed power supply system. Single-stage multi-input inverters allow a variety of new energy inputs, and the nature, amplitude and characteristics of the input sources can be the same or very different. The new single-stage new energy distributed power supply system has the advantages of simple circuit structure, single-stage power conversion, multiple input sources supply power to the load at the same time or time-sharing within a high-frequency switching cycle, and low cost.

Therefore, it is extremely urgent to actively seek a class of single-stage multi-input inverters and their new energy distributed power supply systems that allow a variety of new energy sources to jointly supply power. Utilization will be of great significance.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a multi-input and single-output high-frequency inverter circuit with multiple new energy combined power supply, no common ground for input DC power supply, multiple input and single output high-frequency inverter circuit set in series with simultaneous selection switches, high-frequency isolation between output and input, multiple input The power supply supplies power to the load at the same time or in a time-sharing manner, the circuit topology is simple, the shared output high-frequency isolation transformer cycle-wave transform filter circuit, single-stage power conversion, high conversion efficiency, small output voltage ripple, output medium and small capacity, wide application prospects, etc. A series-connected, forward-cycle-transformed single-stage multi-input high-frequency link inverter for simultaneous power supply.

The technical scheme of the present invention is: a series-connected simultaneous power supply forward cycle-transformed single-stage multi-input high-frequency link inverter is a multi-input single-output high-frequency inverter circuit that converts a plurality of input filters that do not share a common ground. It is connected with a common output high-frequency isolation transformer and cycle-wave transform filter circuit. Each input end of the multi-input single-output high-frequency inverter circuit is connected to the output end of each input filter in one-to-one correspondence. The output end of the frequency inverter circuit is connected with the input end of the high frequency transformer of the output high frequency isolation transformer and cycle wave transform filter circuit. The power switch circuit and bidirectional power flow single-input single-output high-frequency inverter circuit are cascaded in series at the same time, which is equivalent to a bidirectional power flow single-input single-output high-frequency inverter circuit at any time. The selective power switch circuits are all composed of a two-quadrant power switch and a power diode, and the source of the two-quadrant power switch is connected to the cathode of the power diode, and the drain of the two-quadrant power switch and the anode of the power diode are the circuit respectively. The positive and negative input terminals of the power switch circuit are selected in series at the same time, the source of the two-quadrant power switch and the anode of the power diode are respectively the positive and negative output terminals of the power switch circuit in series connection, and the output The high-frequency isolation transformer cycle-wave transformation filter circuit is composed of a high-frequency transformer, a cycle-wave converter, and an output filter cascaded in sequence. Power switch configuration.

The invention is a multi-input inverter circuit structure formed by cascading the DC converter and the inverter of the traditional multiple new energy combined power supply system in two stages, and constructs a new single-stage multi-input inverter with simultaneous selection switches in series The circuit structure, the circuit structure and topology family and its energy management control strategy of the forward cycle-transformed single-stage multi-input high-frequency link inverter with series power supply at the same time are proposed. The multi-input single-output high-frequency inverter circuit is formed by connecting a plurality of input filters that do not share the ground and a common output high-frequency isolation transformer and cycle-wave transform filter circuit.

The series-connected simultaneous power supply forward cycle-transformed single-stage multi-input high-frequency link inverter of the present invention can invert multiple non-common ground and unstable input DC voltages into stable and high-quality output AC power required by a load, It has multi-input DC power supply without common ground, multi-input and single-output high-frequency inverter circuits are not isolated, output and input high-frequency isolation, multi-input power supply simultaneously or time-sharing power supply to the load, simple circuit topology, shared output high-frequency isolation Transformer cycle-wave transform filter circuit, single-stage power transform, high transform efficiency, small output voltage ripple, small and medium output capacity, and wide application prospects. The comprehensive performance of the single-stage multi-input high-frequency link inverter of series-connected simultaneous power supply forward cycle conversion type will be superior to that of the traditional multi-input inverter composed of two-stage cascaded DC converters and inverters.

Description of drawings

Figure 1, a traditional two-stage new energy distributed power supply system with parallel output terminals of multiple unidirectional DC converters.

Figure 2, a traditional two-stage new energy distributed power supply system with multiple unidirectional DC converter outputs connected in series.

Figure 3, the principle block diagram of the new single-stage multi-input inverter.

Figure 4 is a schematic block diagram of a forward cycle-transformed single-stage multi-input high-frequency link inverter with simultaneous power supply in series.

Figure 5 is a circuit structure diagram of a forward cycle-transformed single-stage multi-input high-frequency link inverter with simultaneous power supply in series.

Figure 6, the steady-state principle waveform diagram of the bipolar phase-shift control series power supply forward cycle-converted single-stage multi-input high-frequency link inverter simultaneously.

Figure 7, the steady-state principle waveform diagram of the single-stage multi-input high-frequency link inverter with unipolar phase-shift control series power supply at the same time.

Figure 8, circuit topology example 1 of a forward cycle-transformed single-stage multi-input high-frequency link inverter with simultaneous power supply in series ---- push-pull full-wave circuit schematic diagram.

Fig. 9, the circuit topology example 2 of the forward cycle-transformed single-stage multi-input high-frequency link inverter with simultaneous power supply in series ---- push-pull bridge circuit schematic diagram.

Figure 10, circuit topology example 3 of a forward cycle-transformed single-stage multi-input high-frequency link inverter with simultaneous power supply in series - push-pull forward full-wave circuit schematic diagram.

Figure 11, the circuit topology example of the forward cycle-transformed single-stage multi-input high-frequency link inverter with power supply in series at the same time ---- the schematic diagram of the push-pull forward bridge circuit.

Figure 12, circuit topology example 5 of a forward cycle-transformed single-stage multi-input high-frequency link inverter with simultaneous power supply in series - half-bridge full-wave circuit schematic diagram.

Figure 13, circuit topology example 6 of a forward cycle-transformed single-stage multi-input high-frequency link inverter with simultaneous power supply in series - half-bridge bridge circuit schematic diagram.

Figure 14, circuit topology example 7 of a forward cycle-converted single-stage multi-input high-frequency link inverter with simultaneous power supply in series - full-bridge full-wave circuit schematic diagram.

Figure 15, circuit topology example of a forward cycle-transformed single-stage multi-input high-frequency link inverter with simultaneous power supply in series eight - full-bridge bridge circuit schematic diagram.

Figure 16 is a block diagram of the energy management control block diagram of the output voltage and input current instantaneous value feedback bipolar phase-shifting master-slave power distribution of the forward cycle-transformed single-stage multi-input high-frequency link inverter with simultaneous power supply in series.

Figure 17 shows the waveform diagram of the output voltage and input current instantaneous value feedback bipolar phase-shift master-slave power distribution energy management control principle of the forward cycle-transformed single-stage multi-input high-frequency link inverter with simultaneous power supply in series.

Figure 18 is a block diagram of the energy management control block diagram of the output voltage and input current instantaneous value feedback unipolar phase-shift master-slave power distribution of the forward cycle-transformed single-stage multi-input high-frequency link inverter with simultaneous power supply in series.

Figure 19 is a waveform diagram of the energy management control principle of the output voltage and input current instantaneous value feedback unipolar phase-shift master-slave power distribution of the forward cycle-transformed single-stage multi-input high-frequency link inverter with simultaneous power supply in series.

Figure 20, a single-stage multi-input high-frequency link independent power supply system with an output terminal connected in series with a single-stage isolated bidirectional charge-discharge converter with simultaneous power supply and forward cycle wave conversion.

Figure 21. Maximum power output energy management control strategy with a single-stage isolated bidirectional charge-discharge converter output voltage independent control loop.

Figure 22, the waveforms of the output voltage u _o and the output filter inductor currents i _Lf and i _Lf ' of the independent power supply system.

Detailed ways

The technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments of the specification.

The forward cycle-transformed single-stage multi-input high-frequency link inverter with simultaneous power supply in series is a multi-input single-output high-frequency inverter circuit that isolates multiple input filters that do not share the ground and a common output high-frequency inverter. The voltage-cycle-wave transform filter circuit is connected and formed, each input end of the multi-input single-output high-frequency inverter circuit is connected with the output end of each input filter in one-to-one correspondence, and the output end of the multi-input single-output high-frequency inverter circuit is connected with the output end of each input filter. The high-frequency transformer input ends of the output high-frequency isolation transformer and cycle-wave transform filter circuit are connected to each other, and the multi-input single-output high-frequency inverter circuit is connected in series by the output ends of the multi-channel series in series. The single-input single-output high-frequency inverter circuits are cascaded in sequence, which is equivalent to a bidirectional power flow single-input single-output high-frequency inverter circuit at any time. The power switch is composed of a power diode, and the source of the two-quadrant power switch is connected to the cathode of the power diode. The drain of the two-quadrant power switch and the anode of the power diode are respectively connected in series with the circuit and select the positive and negative poles of the power switch circuit. Negative polarity input terminal, the source of the two-quadrant power switch and the anode of the power diode are respectively the positive and negative output terminals of the power switch circuit in series, and the output high-frequency isolation transformer cycle-wave transform filter circuit It is composed of a high-frequency transformer, a cyclic converter, and an output filter connected in sequence. The cyclic converter is composed of a plurality of four-quadrant high-frequency power switches that can withstand bidirectional voltage stress and bidirectional current stress.

The principle block diagram, circuit structure, and steady-state principle waveforms of bipolar phase-shift control and unipolar phase-shift control inverters of the forward cycle-transformed single-stage multi-input high-frequency link inverter with power supply in series at the same time are shown in the figure respectively. 4, 5, 6, and 7 are shown. In Figures 4, 5, 6, and 7, U _i1 , U _i2 , ..., U _in are n input DC voltage sources (n is a natural number greater than 1), Z _L is a single-phase output AC load (including single-phase AC without source load and single-phase AC grid load), u _o and i _o are the single-phase output AC voltage and AC current, respectively. The n-input single-output high-frequency inverter circuit is composed of a multi-channel series-selected power switch circuit and a bi-directional power flow single-input single-output high-frequency inverter circuit in which the output terminals are connected in series in sequence. The multi-channel series simultaneous selection power switch circuit is composed of n two-quadrant high-frequency power selection switches S _s1 , S _s2 , ..., S _sn and n selection diodes D _s1 , D , which can withstand unidirectional voltage stress and bidirectional current stress. _s2 , ..., D _sn (power selection switches S _s1 , S _s2 , ..., S _sn are turned on at the same time or with a phase difference, the switching frequency is the same or different, here only the analysis of S _s1 , S _s2 , ..., S _sn uses the same The control method of switching frequency and turning on at the same time), bidirectional power flow, single input and single output high-frequency inverter circuit is composed of multiple two-quadrant high-frequency power switches that can withstand unidirectional voltage stress and bidirectional current stress. MOSFET, IGBT can be selected , GTR and other power devices; the output high-frequency isolation transformer cycle-wave transform filter circuit is composed of a high-frequency transformer, a cycle-wave converter, and an output filter cascaded in sequence. Stressed four-quadrant high-frequency power switch implementation, limited space, only the circuit diagram of the LC output filter suitable for passive AC load is drawn, and the circuit diagram of the L or LCL output filter suitable for AC grid load is not drawn. ;The n-channel input filters are LC filters (including filter inductors L _i1 , L _i2 , ..., L _in with dashed boxes) or capacitive filters (without dashed boxes with filter inductors L _i1 , L _i2 , ..., L _in ), when the LC filter is used, the input DC current of n channels will be smoother.

The n-input single-output high-frequency inverter circuit _modulates the n-channel input DC voltage sources U _i1 , U _i2 , . The level SPWM voltage wave u _AB or u _A′B′ is demodulated into bipolar two-state or unipolar three-state multi-level SPWM voltage wave u _CD by the high-frequency transformer T isolation transformer and cycle converter, After the output filter L _f -C _f , a high-quality sinusoidal AC voltage u _o or sinusoidal AC current i _o is obtained on a single-phase AC passive load or a single-phase AC grid, and n inputs are n inputs of a single-output high-frequency inverter circuit After the pulse current passes through the input filters L _i1 -C _i1 , L _i2 -C _i2 , ..., L _in -C _in or C _i1 , C _i2 , ..., C _in n channels of DC power supply U _i1 , U _i2 , ... , U _in to obtain smooth input DC currents I _i1 , I _i2 , . . . , I _in . It should be added that the amplitude of the bipolar two-state multi-level high-frequency voltage square wave and the bipolar three-state multi-level SPWM voltage wave u _AB or u _A'B' is ±2(U _i1 +U _i2 +…+U _in ) (push-pull circuit), ±(U _i1 +U _i2 +…+U _in ) (push-pull forward, full-bridge circuit), ±1/2(U _i1 +U _i2 +…+U _in ) (half-bridge circuit), the amplitude of u _CD is ±(U _i1 N ₂ /N ₁ +U _i2 N ₂ /N ₁ +…+U _in N ₂ /N ₁ ) (push-pull type, push-pull forward type, full-bridge circuit), ±1/2 (U _i1 N ₂ /N ₁ +U _i2 N ₂ /N ₁ +…+U _in N ₂ /N ₁ ) (half-bridge circuit ).

The series-connected simultaneous power supply forward cycle-transformed single-stage multi-input high-frequency link inverter is a step-down inverter, and n input sources can supply power to the load at the same time. The principle of this inverter is equivalent to the superposition of multiple forward cycle-transformed (voltage-type) single-input inverters at the output terminal voltage, that is, the output voltage u _o and the input DC voltage (U _i1 , U _i2 , ..., U _in ), high frequency transformer turns ratio N ₂ /N ₁ , duty cycle (d ₁ , d ₂ , ..., d _j , ..., d _n ) is related by u _o =[u _i1 (d ₁ + d _k -d _j+1 )+u _i2 (d ₂ +d _k -d _j+1 )+…+u _ij (d _j +d _k -d _j+1 )+u _ij+1 d _k +…+ u _ik d _k +u _ik+1 d _k+1 +…u _in d _n ]N ₂ /N ₁ (unipolar phase shift control) or u _o =[u _i1 (d _j+1 -d _k+1 )+u _i2 (d _j+1 -d _k+1 )+…+u _ij+1 (d _j+1 -d _k+1 )+u _ij+2 (d _j+1 +d _j+2 -2d _k+1 )/2+u _ij+3 (d _j+1 +d _j+3 -2d _k+1 )/2+…+u _ik (d _j+1 +d _k -2d _k+1 )/2 +u _ik+1 (d _j+1 -d _k+1 )/2+…+u _in (d _j+1 -d _k+1 )/2]N ₂ /N ₁ (bipolar phase shift control) , where 1≤j, k≤n. For appropriate phase shift angle θ and high frequency transformer turns ratio N ₂ /N ₁ , u _o can be greater than, equal to or less than the sum of the input DC voltages U _i1 +U _i2 +...+U _in , the high voltage in the inverter The frequency transformer not only plays a role in improving the safety, reliability and electromagnetic compatibility of the inverter operation, but more importantly, it plays a role in matching the output voltage and the input voltage, that is, the output voltage of the inverter is higher than, equal to or lower than The technical effect of the sum of input DC voltages U _i1 +U _i2 +…+U _in , its application range has been greatly expanded. Since 0≤θ≤180 ^o exists, it can be deduced that u _o <(U _i1 +U _i2 +…+U _in )N ₂ /N ₁ , that is, the output voltage u _o is always lower than the input DC voltage (U _i1 , U _{i2 , . _ _ _ _ _ _} The operating frequency of the transformer is high frequency, and the n-input single-output high-frequency inverter circuit is equipped with a multi-channel series-connected power switch circuit with the output terminals connected in series at the same time. type (step-down type) single-stage multi-input high-frequency link inverter. The n input sources of the inverter supply power to the output AC load at the same time or time-sharing within a high-frequency switching cycle, and the duty cycle can be the same (d ₁ =d ₂ =...=d _n ) or different (d ₁ ≠d ₂ ≠…≠d _n ).

The single-stage multi-input high-frequency link inverter of the series-connected simultaneous power supply forward cycle-transformation type of the present invention shares a multi-input single-output high-frequency inverter circuit and an output high-frequency isolation variable-voltage cycle-transform filter circuit. There is an essential difference in the circuit structure of the traditional multi-input inverter composed of two-stage cascaded DC converters and inverters. Therefore, the inverter of the present invention is novel and creative, and has the advantages of high-frequency isolation of output and input, simultaneous or time-sharing power supply of multiple input power sources, simple circuit topology, single-stage power conversion, large boost ratio, and input voltage configuration. It has the advantages of flexibility, high conversion efficiency (meaning low energy loss), small output voltage ripple, small and medium output capacity, low cost, and wide application prospects. It is an ideal energy-saving and consumption-reducing single-stage multi-input inverter. Vigorously advocating the construction of an energy-saving and conservation-oriented society is more valuable today.

The circuit topology family embodiments of the forward cycle-transformed single-stage multi-input high-frequency link inverter with simultaneous power supply in series are shown in Figures 8, 9, 10, 11, 12, 13, 14, and 15. In the circuit shown in Figure 8-15, the multi-channel series simultaneous selection power switch circuits whose output terminals are connected in series are composed of n two-quadrant high-frequency power switches that can withstand unidirectional voltage stress and bidirectional current stress, and n diodes. The bidirectional power flow single-input single-output high-frequency inverter circuit is composed of multiple two-quadrant high-frequency power switches that can withstand unidirectional voltage stress and bidirectional current stress (as shown in Figures 8, 9, 10, 11, 12, and 13). The push-pull, push-pull forward and half-bridge circuits are composed of two two-quadrant high-frequency power switches, and the full-bridge circuit shown in Figures 14 and 15 is composed of four two-quadrant high-frequency power switches), and the output is cyclically converted The circuit is implemented by multiple four-quadrant high-frequency power switches. To be precise, the push-pull full-wave, push-pull forward full-wave and half-bridge full-wave circuits shown in Figs. It is realized by quadrant high-frequency power switch, n diodes and two four-quadrant high-frequency power switches that can withstand bidirectional voltage stress and bidirectional current stress. , The half-bridge bridge circuit is composed of n+2 two-quadrant high-frequency power switches that can withstand unidirectional voltage stress and bidirectional current stress, n diodes and 4 four-quadrant high-frequency switches that can withstand bidirectional voltage stress and bidirectional current stress. The full-bridge full-wave and full-bridge bridge circuits shown in Figures 14 and 15 are composed of 2 or 4 four-quadrant high-frequency power switches that can withstand bidirectional voltage stress and bidirectional current stress, and n+4 power switches. It is realized by a two-quadrant high-frequency power switch and n diodes that can withstand unidirectional voltage stress and bidirectional current stress. It should be added that the circuits shown in Figures 8, 9, 10, 11, 12, 13, 14, and 15 show the case where the input filter is an LC filter, but the case where the input filter is a capacitor filter is not given due to space limitations. The circuit shown in Figures 10 and 11 and the half-bridge circuit shown in Figures 12 and 13 are only suitable for the situation where the duty ratios of n input power supplies are basically equal; the circuits shown in Figures 8-15 only The circuit diagram of the LC output filter suitable for passive AC loads is drawn, but the circuit diagram of the L or LCL output filter suitable for the AC grid load is not drawn. Table 1 shows the power switch voltage stress of the eight topological embodiments of the forward cycle-transformed single-stage multi-input high-frequency link inverter with simultaneous power supply in series. Push-pull and push-pull forward circuits are suitable for medium-power low-voltage input inverter applications, half-bridge circuits are suitable for low-power high-voltage input inverter applications, and full-bridge circuits are suitable for medium-power high-voltage input inverter applications. This circuit topology family is suitable for converting multiple common ground and unstable input DC voltages into a stable and high-quality output AC power with the required voltage, which can be used to realize new single-stage multiple new energy sources with excellent performance and wide application prospects Distributed power supply system, such as photovoltaic cell 40-60VDC/220V50HzAC or 115V400HzAC, 10kw proton exchange membrane fuel cell 85-120V/220V50HzAC or 115V400HzAC, small and medium-sized household wind power 24-36-48VDC/220V50HzAC or 115V400HzAC, large wind power 510VDC /220V50HzAC or 115V400HzAC and other multi-input sources supply power to the AC load or AC grid.

Table 1 Power switch voltage stress of eight topological examples of forward cycle-transformed single-stage multi-input high-frequency link inverters with simultaneous power supply in series

Energy management and control strategies are crucial for a variety of new energy combined power supply systems. Since there are multiple input sources and corresponding power switch units, multiple duty ratios need to be controlled, that is, there are multiple control degrees of freedom, which provides the possibility for energy management of multiple new energy sources. The energy management control strategy of the forward cycle-transformed single-stage multi-input high-frequency link inverter with simultaneous power supply in series requires the energy management of the input source, the MPPT of the new energy power generation equipment such as photovoltaic cells and wind turbines, and the output voltage ( The three major functions of current) control, and sometimes the charge and discharge control of the battery and the smooth and seamless switching of the system under different power supply modes need to be considered. The forward cycle-transformed single-stage multi-input high-frequency link inverter with simultaneous power supply in series adopts two different energy management modes: (1) Energy management mode I - master-slave power distribution mode, the power required by the known load is as much as possible Provided by the 1st, 2nd, ..., n-1 input sources of the main power supply equipment, given the input current of the 1st, 2nd, ..., n-1 input sources, it is equivalent to the given 1st, 2nd, ..., n The input power of -1 input source, the insufficient power required by the load is provided by the nth input source from the power supply equipment, and there is no need to add battery energy storage equipment; (2) Energy management mode II - maximum power output mode, the first , 2, ..., n input sources are all output to the load with the maximum power, eliminating the need for battery energy storage equipment, and realizing the full utilization of energy by the grid-connected power generation system. It can realize the stability of the output voltage (current) of the independent power supply system. When the input voltages of the n new energy sources are all given, by controlling the input current of the first, second, ..., n input sources, it is equivalent to controlling the input power of the first, second, ..., n input sources.

The forward cycle-transformed single-stage multi-input high-frequency link inverter with simultaneous power supply in series adopts the output voltage and input current instantaneous value feedback bipolar phase-shifting and unipolar phase-shifting master-slave power distribution energy management control strategy to form Independent power supply system; or adopt the input current instantaneous value feedback bipolar phase shift, unipolar phase shift maximum power output energy management control strategy to form a grid-connected power generation system. The output voltage and input current instantaneous value feedback bipolar SPWM, unipolar SPWM master-slave power required by the 1st, 2nd,..., n-1 input sources with fixed output power and the nth input source supplementing the load required by the load Distribution energy management control block diagram and control principle waveform, as shown in Figure 16, 17, 18, 19 respectively. The basic idea of the bipolar phase-shift control scheme shown in Figures 16 and 17 is that the n-input single-output high-frequency inverter circuit generates a bipolar two-state multi-level high-frequency square wave. The conduction time of the -1 channel selection power switch is allocated according to the size of the error current (to achieve the maximum power output of the 1st, 2nd, ..., n-1 channels of input sources), and the conduction time of the nth channel power switch is based on The signal smaller than the error current signal of the n-1th channel and the difference between T _s /2 and the turn-on time of the first channel selection power switch are obtained (to achieve the complement of the nth channel input source power), there will always be multiple channels or One input source is connected to ensure the forward transfer of energy from multiple input sources, and the natural path for energy feedback is that n input sources are connected in series. To achieve the stability of the output voltage of the inverter, the natural commutation of the leakage inductance energy of the high-frequency transformer and the zero-current switching of the cyclic converter are realized by means of the commutation overlap of the cyclic converter. This control strategy is suitable for the circuit shown in Figure 8-15. The reference current signals I ^* _i1r , I ^* _i2r , ..., I ^* _i(n-1)r are obtained after the 1st, 2nd, ..., n-1 input sources are calculated by the maximum power point. The inverter's 1st, 2nd The input current feedback signals I _i1f , I _i2f , ... , I _i(n-1)f of the , ..., n-1 channels are respectively connected with the reference current signals I _i1r , I i2r , I _i2r , ..., I _i(n-1)r is amplified by the proportional-integral regulator, and the current error amplification signals I _1e , I _2e , ..., I _(n-1)e , kI _(n-1)e (0<k< 1) Compare with the shifted unipolar sawtooth carrier -u _c +U _cm /2, and obtain the control signal of the n-input single-output high-frequency inverter circuit in series while selecting the power switch after the appropriate combinational logic circuit u _gss1 , u _gss2 , . . . , u _gssn ; the bipolar sawtooth carrier u _c is divided into two by the rising edge to obtain the control signal u _gs1 (u _gs4 ) of the power switch of the n-input single-output high-frequency inverter circuit and its inverse The phase signal u _gs2 (u _gs3 ); the output voltage feedback signal _{u of} the inverter and the reference sinusoidal voltage ur are amplified by the proportional-integral regulator, and the voltage error amplification signal _ue is respectively related to the bipolar sawtooth carrier _uc and -U _c comparison, consider the polarity selection signal of the output inductor current i _Lf and obtain the control signals u _gs5 (u _gs′5 ) and u _gs6 (u _gs′6 ) of the power switch of the cycloconverter after an appropriate combinational logic circuit , _ugs7 ( _ugs'7 ), _ugs8 ( _ugs'8 ). When the load power P _o is greater than the sum of the maximum powers of the 1st, 2, ..., n-1 input sources, the output voltage u _o decreases, and the effective value of the output voltage _ue of the voltage regulator is greater than the threshold comparison level U _{t And I 1e , I 2e} , . Work independently with the n-th voltage regulator, that is, I _i1r =I ^* _i1r , I _i2r =I ^* _i2r ,..., I _i(n-1)r =I ^* _i(n-1)r , the first, 2, ..., n-1 current regulators are used to achieve the maximum power output of the 1st, 2, ..., n-1 input sources, the nth voltage regulator is used to stabilize the output voltage of the inverter, and the nth input The source supplies power to the load at the same time or time-sharing; when the load power P _o is less than the sum of the maximum powers of the 1st, 2nd, ..., n-1 input sources, the output voltage u _o increases, and when the voltage regulator output voltage u _e When the rms value of t is lower than the threshold comparison level U _t , the diode D _n-1 is turned on, D ₁ , D ₂ , ..., D _n-2 are still blocked, and the hysteresis comparator circuit n+1 outputs a low level, The nth input source stops the power supply, the voltage regulator and the current regulator form a double closed-loop control system, the 1st, 2nd, ..., n-1th input sources supply power to the load at the same time or time-sharing within one switching cycle, and the current regulator The reference current I _i(n-1)r decreases, i.e. I _i(n-1)r <I ^* _i(n-1)r , the output power of the n-1th input source decreases (working at non-maximum operation) point), the output power of the nth input source drops to zero, and the output voltage u _o of the inverter tends to be stable. When the input voltage or load changes, the error voltage signal _ue and the error current signal I _1e , I _2e , . . . , I ( _{n -1)e ,} kI _{(n- 1) e} , thereby changing the duty _ratios d ₁ , d ₂ , .

The basic idea of the unipolar phase-shift control scheme shown in Figures 18 and 19 is to generate bipolar three-state multi-level through the phase shift between the right bridge arm and the left bridge arm of the n-input single-output high-frequency inverter circuit SPWM wave, the cycloconverter demodulates the bipolar tristate multilevel SPWM wave into unipolar tristate multilevel SPWM wave, the bipolar tristate multilevel output by the cycloconverter in the high frequency inverter circuit Switching is performed during the zero period of the SPWM wave to realize zero-voltage switching. At any time, there are always multiple or one input source access (“1” state or “-1” state, which ensures the forward transfer or reverse feedback of energy. ) or 0 state (freewheeling state), and the natural path of energy feedback is that n input sources are connected in series. This control strategy is only applicable to the circuits shown in Figures 14 and 15. The conduction time of the 1st, 2nd,..., n-1 way selection power switch is to distribute the OR signal u _sum of the left bridge arm and the right bridge arm conduction signal according to the size of the error current according to the size of the error current (to realize the first, 2, ..., the maximum power output of the n-1 input source), and the conduction time of the nth power switch is obtained according to the signal distribution less than the n-1th error current signal (to realize the power of the nth input source power) supplement). The reference current signals I ^* _i1r , I ^* _i2r , ..., I ^* _i(n-1)r are obtained after the 1st, 2nd, ..., n-1 input sources are calculated by the maximum power point. The inverter's 1st, 2nd The input current feedback signals I _i1f , I _i2f , ... , I _i(n-1)f of the , ..., n-1 channels are respectively connected with the reference current signals I _i1r , I i2r , I _i2r , ..., I _i(n-1)r is amplified by the proportional-integral regulator, and the current error amplification signals I _1e , I _2e , ..., I _(n-1)e , kI _(n-1)e (0<k< 1) The control signals u _gss1 , u _gss2 , . . . , u _gssn of the power switch are selected in series with the n-input single-output high-frequency inverter circuit through the divider, the multiplier, the comparator and the appropriate logic circuit respectively; The output voltage feedback signal _{u of} and the reference sinusoidal voltage ur are compared and amplified by the proportional-integral regulator, and the voltage error amplification signal _ue and its inverse signal _-ue are compared with the bipolar sawtooth carrier _uc respectively, and the The power switch control signals _ugs1 , _ugs2 , _ugs3 , _ugs4 of the n-input single-output high-frequency inverter circuit are obtained after the falling edge divides the frequency by two and the NOT gate circuit; in the figure, u _sum represents the n-input single-output high-frequency inverter The OR signal of the conduction signal of the left bridge arm and the right bridge arm of the circuit, U _summ is the level amplitude of _{u sum} , I _1em is the maximum value of the current error amplification signal I _1e ; The control signals _ugs5 ( _ugs′5 ), _ugs6 ( _ugs′6 ), _ugs7 ( _ugs′7 ), and _ugs8 ( _ugs′8 ) of the power switch of the cycloconverter are obtained after dividing the frequency by two.

The 1st, 2nd, ..., n-1 current regulators and the nth voltage regulators work independently respectively, and the 1st, 2, ..., n-1 current regulators are used to realize the 1st, 2, ..., n- The maximum power output of 1 input source, the nth voltage regulator is used to stabilize the output voltage of the inverter, and the n input sources supply power to the load at the same time or in time-sharing. When the input voltage or load changes, by adjusting the reference voltage ur and the reference current I _i1r , I _i2r , ..., I _{i(n-1)r ,} or adjusting the feedback voltage u _of and the feedback current I _i1f , I _i2f , ... , I _i(n-1)f to change the error voltage signal ue and error current signals I _1e , I _2e , . . . , I _{(n-1)e ,} kI _(n-1)e , thereby changing the duty cycle d ₁ , d ₂ , ..., _dn and the phase shift angle θ, so the regulation and stabilization of the inverter output voltage and input current (output power) can be realized.

The bipolar phase-shifting control principle waveform shown in Figure 17 indicates the high-frequency switching period T _S and the on-time T _on1 , T of the first, second, ..., n input sources in a certain high-frequency switching period T _{S on2 , . _ _ _ _} The on-time T _com and the phase shift angle θ vary sinusoidally within one output voltage cycle. In addition, for the half-bridge circuit shown in Figures 12 and 13, half of the input DC voltage values (U _i1 /2, U _i2 /2, ..., U _in /2) should be substituted into the voltage transfer ratio formula for calculation .

In order to form an independent power supply system that can make full use of the energy of multiple input sources, multiple input sources should work in the maximum power output mode and need to be equipped with energy storage devices to stabilize the output voltage, that is, connect one in parallel at the output end of the inverter. A single-stage isolated bidirectional charge-discharge converter, as shown in Figure 20. The single-stage isolated bidirectional charge-discharge converter consists of an input filter (L _i , C _i or C _i ), a high-frequency inverter, a high-frequency transformer, a cyclic converter, and an output filter (L _f ′, C _f ′). ) are cascaded in sequence, and the cycloconverter is composed of four-quadrant high-frequency power switches that can withstand bidirectional voltage stress and bidirectional current stress. The single-stage isolated bidirectional charge-discharge converter is equivalent to a single-stage high-frequency link DC-AC converter and a single-stage high-frequency link DC-AC converter when the energy is transferred forward (discharging the energy storage device) and in the reverse direction (charging the energy storage device). A single stage high frequency link AC-DC converter.

The independent power supply system adopts a maximum power output energy management control strategy with a single-stage isolated bidirectional charge-discharge converter output voltage independent control loop, as shown in Figure 21. When the load power P _o =U _o I _o is greater than the sum of the maximum powers of multiple input sources P _1max +P _2max +...+P _nmax , the energy storage devices such as batteries and supercapacitors pass the single-stage isolation bidirectional charge-discharge converter to the The load provides the required insufficient power—power supply mode II, the energy storage device supplies power to the load alone—power supply mode III, which is an extreme case of power supply mode II; when the load power P _o =U _o I _o is less than the maximum value of multiple input sources When the sum of power is P _1max +P _2max +...+P _nmax , the residual energy output by multiple input sources charges the energy storage device through the single-stage isolated bidirectional charge-discharge converter - power supply mode I. Taking a resistive load as an example, the power flow control of a single-stage isolated bidirectional charge-discharge converter is discussed, as shown in Figure 22. For the output filter capacitors C _f , C _f ′ and the load Z _L , the output terminals of the single-stage multi-input high-frequency link inverter and the single-stage isolated bidirectional charge-discharge converter are connected in parallel with the simultaneous power supply in series. in the parallel superposition of two current sources. It can be seen from the energy management control strategy shown in Figure 21 that the output filter inductor current i _Lf and the output voltage u _o have the same frequency and phase, and output active power; The discharge converter is controlled by the error amplification signal u _oe of the output voltage u _o and the reference voltage u _oref and the high frequency carrier to generate the SPWM signal for control, and there is a phase difference θ between the output filter inductor current i _Lf ′ and u _o , Different phase difference θ means outputting active power of different magnitude and direction. When P _o =P _1max +P _2max +...+P _nmax , θ=90°, the active power output by the charge-discharge converter is zero, and it is in a no-load state; when P _o >P _1max +P _2max +...+P When _nmax , u _o decreases, θ<90°, the charge-discharge converter outputs active power, and the energy storage device discharges the load, that is, the energy storage device provides insufficient power required by the load; when P _o <P _1max +P _2max + When ...+P _nmax , u _o increases, θ > 90°, the charge-discharge converter outputs negative active power, and the load feeds back energy to the energy storage device, that is, the residual power output by multiple input sources charges the energy storage device, when θ When =180°, the energy returned by the load to the energy storage device is the largest. Therefore, the energy management control strategy can control the power flow size and direction of the single-stage isolated bidirectional charge-discharge converter in real time according to the relative size of P _o and P _1max +P _2max +…+P _nmax , and realize the system in three different power supply. Smooth and seamless switching between modes.

Claims (2)

1. The utility model provides a series connection is power supply forward cycle conversion type single-stage multiple input high frequency link inverter simultaneously which characterized in that: the inverter is formed by sequentially cascading a bidirectional power flow n-input single-output series simultaneous selection power switch circuit, a bidirectional power flow single-input single-output high-frequency inverter circuit, a high-frequency transformer, a cycle converter and an output filter, wherein each input end of the bidirectional power flow n-input single-output series simultaneous selection power switch circuit is cascaded with one input filter, no common end exists among the n input filters, n is the number of multiple input sources, and n is a natural number greater than 1; the bidirectional power flow n-input single-output series simultaneous selection power switch circuit is formed by connecting n paths of bidirectional power flow in series while selecting the power switch circuit in a positive polarity output end and a negative polarity output end of each path in series, and each path of bidirectional power flow in series while selecting the power switch circuit is formed by selecting two-quadrant power capable of bearing unidirectional voltage stress and bidirectional current stressThe power selection circuit comprises a selection switch and a power selection diode, wherein the source electrode of a two-quadrant power selection switch is connected with the cathode of the power selection diode, the drain electrode of the two-quadrant power selection switch and the anode of the power selection diode are respectively used as the positive and negative input ends of the bidirectional power flow series connection simultaneous selection power switch circuit, and the source electrode of the two-quadrant power selection switch and the anode of the power selection diode are respectively used as the positive and negative output ends of the bidirectional power flow series connection simultaneous selection power switch circuit; the bidirectional power flow single-input single-output high-frequency inverter circuit is a push-pull type, push-pull forward type, half-bridge type or full-bridge type circuit, the push-pull type circuit is composed of two quadrant high-frequency power switches bearing unidirectional voltage stress and bidirectional current stress, the source electrodes of the two quadrant high-frequency power switches are connected with the negative polarity output end of the series simultaneous selection power switch circuit, the drain electrodes of the two quadrant high-frequency power switches are respectively connected with two different ends of a primary winding of a high-frequency transformer, a center tap of the primary winding of the high-frequency transformer is connected with the positive polarity output end of the series simultaneous selection power switch circuit, the push-pull forward type circuit is composed of two quadrant high-frequency power switches bearing unidirectional voltage stress and bidirectional current stress and a clamping capacitor, the drain electrode and the source electrode of one two quadrant high-frequency power switch are respectively connected with the non-end of one primary winding of the high-frequency transformer and the-end of the other primary winding, and the positive output end of the selective power switch circuit is connected, the drain and source of another two-quadrant high-frequency power switch are respectively connected with the "·" end of one primary winding of the high-frequency transformer and the "·" end of another primary winding, and its source is connected with the negative output end of the series connection simultaneous selective power switch circuit, two ends of the clamping capacitor are respectively connected with the "·" ends of two primary windings of the high-frequency transformer, the half-bridge circuit is formed from two capacitors of left bridge arm and two high-frequency power switches of right bridge arm which bear unidirectional voltage stress and bidirectional current stress, and the drain and source of the right upper bridge arm switch are respectively connected with the positive end of the left upper bridge arm capacitor and the drain of the right lower bridge arm switch, the source of the right lower bridge arm switch is connected with the negative end of the left lower bridge arm capacitor, andtwo ends of a primary winding of the high-frequency transformer are respectively connected with the midpoint of a right bridge arm switch and the midpoint of a left bridge arm capacitor, a full-bridge circuit is composed of four two-quadrant high-frequency power switches bearing unidirectional voltage stress and bidirectional current stress of a left bridge arm, a right bridge arm or an upper bridge arm and a lower bridge arm, drain electrodes of the two upper bridge arm switches are connected with a positive polarity output end of a series connection simultaneous selection power switch circuit, source electrodes of the two lower bridge arm switches are connected with a negative polarity output end of the series connection simultaneous selection power switch circuit, one end of the primary winding of the high-frequency transformer is connected with the source electrode of the left upper bridge arm switch and the drain electrode of the left lower bridge arm switch, and the other end of the primary winding; the cycle converter is a full-wave and full-bridge circuit, the full-wave cycle converter is composed of two four-quadrant high-frequency power switches bearing bidirectional voltage stress and bidirectional current stress, one drain electrode of the two four-quadrant high-frequency power switches is respectively connected with two different ends of a secondary winding of the high-frequency transformer, the other drain electrode of the two four-quadrant high-frequency power switches and a center tap of the secondary winding of the high-frequency transformer are connected with the input end of an output filter, the full-bridge cycle converter is composed of four-quadrant high-frequency power switches bearing bidirectional voltage stress and bidirectional current stress of a left bridge arm, a right bridge arm or an upper bridge arm and a lower bridge arm, the drain electrodes of the two upper bridge arm switches and the drain electrodes of the two lower bridge arm switches are respectively connected with two different ends of the secondary winding of the high-frequency transformer, and the other drain electrodes of the left upper bridge arm switch and the left lower bridge arm switch and the other drain electrodes of the right upper bridge arm switch and the right lower bridge arm switch are connected with the input end of the output filter; the bidirectional power flow n-input single-output series simultaneous selection power switch circuit and the bidirectional power flow single-input single-output high-frequency inverter circuit of the inverter input n paths of direct-current voltage sources U into the inverter_i1、U_i2、…、U_inModulating into bipolar two-state multi-level high-frequency voltage square wave or bipolar three-state multi-level SPWM voltage wave with level amplitude changing with input power supply number, demodulating into bipolar two-state or unipolar three-state multi-level SPWM voltage wave through high-frequency transformer isolation voltage transformation and cycle converter, obtaining high-quality sinusoidal AC voltage on single-phase AC load after passing through output filterOr grid-connected sine current, and the voltage wave level amplitudes before and after the push-pull circuit demodulation are respectively +/-2 (U)_i1+U_i2+…+U_in)、±(U_i1N₂/N₁+U_i2N₂/N₁+…+U_inN₂/N₁) The voltage wave level amplitudes before and after the demodulation of the push-pull forward circuit and the full-bridge circuit are respectively +/-U_i1+U_i2+…+U_in)、±(U_i1N₂/N₁+U_i2N₂/N₁+…+U_inN₂/N₁) The voltage wave level amplitudes before and after the half-bridge circuit demodulation are respectively +/-1/2 (U)_i1+U_i2+…+U_in)、±1/2(U_i1N₂/N₁+U_i2N₂/N₁+…+U_inN₂/N₁)，N₁、N₂The number of turns of a primary winding and the number of turns of a secondary winding of the high-frequency transformer are respectively; the voltage stress of the 1 st, 2 nd, … th power selection switch and the n-way power selection diode is U respectively_i1、U_i2、…、U_inThe voltage stress of the two-quadrant power switch of the push-pull type and push-pull forward type, half-bridge type and full-bridge type high-frequency inverter circuits is respectively 2 (U)_i1+U_i2+…+U_in)、U_i1+U_i2+…+U_inThe voltage stress of the two-quadrant power switch of the full-wave and full-bridge cycloconverters of the push-pull, push-pull forward and full-bridge circuits is respectively 2 (U)_i1+U_i2+…+U_in)N₂/N_1、(U_i1+U_i2+…+U_in)N₂/N₁The voltage stress of the two-quadrant power switch of the full-wave and full-bridge cycloconverter of the half-bridge circuit is (U)_i1+U_i2+…+U_in)N₂/N_1、(U_i1+U_i2+…+U_in)N₂/(2N₁) (ii) a The independent power supply system formed by the inverter adopts the output voltage and input current instantaneous values of the output power of the No. 1, No. 2, No. … and the No. 1 input source with the n input source power supply smooth switching function and the output power required by the No. n input source to supplement the load to feed back the bipolar powerThe grid-connected power generation system formed by the inverters adopts a SPWM control strategy of maximum power output energy management of bipolar phase shift and unipolar phase shift fed back by instantaneous values of input currents of input sources of 1 st, 2 nd, … th paths and n paths; the control strategy of the bipolar phase-shifting master-slave power distribution energy management SPWM is that the front n-1 paths of input sources of the inverter output a reference current signal I through the maximum power point calculation^＊ _i1r、I^＊ _i2r、…、I^＊ _i(n-1)rFront n-1 input current feedback signal I_i1f、I_i2f、…、I_i(n-1)fRespectively with the front n-1 base quasi-current signal I_i1r、I_i2r、…、I_i(n-1)rThe amplified signal is compared and amplified by a proportional-integral regulator to output a current error amplified signal I_1e、I_2e、…、I_(n-1)e、kI_(n-1)eRespectively with shifted unipolar sawtooth-shaped carrier-u_c+U_cm2 comparison and output of control signal u in series connection with simultaneous selection of power switches after passing through appropriate combinational logic circuit_gss1、u_gss2、…、u_gssnK is more than 0 and less than 1, and a bipolar sawtooth carrier u_cControl signal u of high-frequency inverter circuit power switch output by rising edge frequency division_gs1(u_gs4) And its inverse signal u_gs2(u_gs3) Output voltage feedback signal u of inverter_ofWith reference sinusoidal voltage u_rThe proportional-integral regulator compares and amplifies an output voltage error amplification signal u_e，u_eRespectively associated with bipolar sawtooth-shaped carriers u_cAnd-u_cComparing and considering output inductor current i_LfThe polarity selection signal is output to a control signal u of a power switch of the cycloconverter after passing through a proper combinational logic circuit_gs5(u_gs′5)、u_gs6(u_gs′6)、u_gs7(u_gs′7)、u_gs8(u_gs′8) When the load power P_oOutput voltage u is larger than the sum of maximum powers of the first n-1 input sources_oReducing, voltage regulator output voltage u_eIs greater than the threshold comparison level U_tAnd I_1e、I_2e、…、I_(n-1)eAre all greater than zero, diode D₁、D₂、…、D_n-1The blocking, front n-1 circuit current regulator and the nth circuit voltage regulator work independently respectively, i.e. I_i1r＝I^＊ _i1r、I_i2r＝I^＊ _i2r、…、I_i(n-1)r＝I^＊ _i(n-1)rThe front n-1 circuit current regulator is used for realizing the maximum power output of the front n-1 circuit input sources, the nth circuit voltage regulator is used for realizing the stabilization of the output voltage of the inverter, the n circuit input sources simultaneously supply power to the load, and when the load power P is_oOutput voltage u less than the sum of the maximum powers of the first n-1 input sources_oIncreasing, voltage regulator output voltage u_eIs reduced to a threshold comparison level U_tFollowing time diode D_n-1On, D₁、D₂、…、D_n-2The output of the hysteresis comparison circuit n +1 is low level, the nth input source stops supplying power, the voltage regulator and the current regulator form a double closed loop control system, the front n-1 input source simultaneously supplies power to the load in a switching period, and the reference current I of the current regulator_i(n-1)rDecrease, i.e. I_i(n-1)r＜I^＊ _i(n-1)rThe output power of the (n-1) th input source is reduced and works at a non-maximum working point, the output power of the (n) th input source is reduced to zero, and the output voltage u of the inverter_oTends to be stable; the SPWM control strategy for unipolar phase-shift master-slave power distribution energy management is that the front n-1 paths of input sources of the inverter output a reference current signal I through maximum power point calculation^＊ _i1r、I^＊ _i2r、…、I^＊ _i(n-1)rInput current feedback signal I of front n-1 path_i1f、I_i2f、…、I_i(n-1)fRespectively with the front n-1 base quasi-current signal I_i1r、I_i2r、…、I_i(n-1)rThe amplified signal is compared and amplified by a proportional-integral regulator to output a current error amplified signal I_1e、I_2e、…、I_(n-1)e、kI_(n-1)eWith output series-connected simultaneous selection of power switches, each passing through a divider, multiplier, comparator and appropriate logicControl signal u_gss1、u_gss2、…、u_gssnOutput voltage feedback signal u of inverter_ofWith reference sinusoidal voltage u_rThe proportional-integral regulator compares and amplifies an output voltage error amplification signal u_e，u_eAnd its inverse signal-u_eRespectively associated with bipolar sawtooth-shaped carriers u_cComparing and outputting a power switch control signal u of the high-frequency inverter circuit after passing through a falling edge frequency-halving and NOT circuit_gs1、u_gs2、u_gs3、u_gs4K, u in control block diagram_sum、U_summ、I_1emRespectively representing coefficients less than 1 and greater than 0, or signals and u of conducting signals of left bridge arm and right bridge arm of high-frequency inverter circuit_sumLevel amplitude, current error amplification signal I_1eMaximum value of (1), bipolar sawtooth carrier u_cOutputting a control signal u of a power switch of the cycloconverter after frequency division by two rising edges_gs5(u_gs′5)、u_gs6(u_gs′6)、u_gs7(u_gs′7)、u_gs8(u_gs′8) (ii) a The inverter determines the number of input sources needing to be put into operation by controlling the connection and disconnection of n paths of bidirectional power flow series connection and simultaneously selecting the power switch according to the size of the alternating current load, and the n paths of input sources are U-shaped in one high-frequency switching period_i1+U_i2+…+U_in、U_i1+U_i2+…+U_in-1、…、U_i1The serial connection in sequence supplies power to the AC load at the same time, which realizes the single-stage high-frequency isolation high-efficiency inversion of n input DC voltages which are not common to the ground and unstable into a stable high-quality sine AC power required by the AC load.

2. The series simultaneous supply forward cycle conversion type single-stage multiple-input high-frequency link inverter according to claim 1, characterized in that: the output end of the series simultaneous power supply forward cycle conversion type single-stage multi-input high-frequency link inverter is connected with a single-stage isolation bidirectional charge-discharge converter of the energy storage device in parallel, so that an independent power supply system which can fully utilize n input source energy and has stable output voltage is formed; the single-stage isolation bidirectional charge-discharge converter is formed by sequentially cascading an input filter, a high-frequency inverter, a high-frequency transformer, a cycle converter and an output filter, wherein the cycle converter is formed by a four-quadrant high-frequency power switch capable of bearing bidirectional voltage stress and bidirectional current stress, and the single-stage isolation bidirectional charge-discharge converter is respectively equivalent to a single-stage voltage type high-frequency link DC-AC converter and a single-stage current type high-frequency link AC-DC converter when the energy storage equipment is discharged and charged; the independent power supply system adopts a management control strategy of the maximum power output energy of n input sources with a single-stage isolation bidirectional charge-discharge converter output voltage independent control loop, the n input sources all work in a maximum power output mode, the power flow size and direction of the single-stage isolation bidirectional charge-discharge converter are controlled in real time according to the relative size of the sum of the load power and the maximum power of the n input sources, and the smooth seamless switching of the output voltage of the system and the charge and discharge of energy storage equipment is realized; when the load power is greater than the sum of the maximum powers of the n input sources, the system works in a power supply mode II in which the energy storage device provides required insufficient power to the load through the single-stage isolation bidirectional charge-discharge converter, a power supply mode III in which the energy storage device supplies power to the load independently belongs to the extreme situation of the power supply mode II, and when the load power is less than the sum of the maximum powers of the n input sources, the system works in a power supply mode I in which the residual energy output by the n input sources charges the energy storage device through the single-stage isolation bidirectional charge-discharge converter; for an output filter capacitor and a load, the output ends of the forward cycle conversion type single-stage multi-input high-frequency link inverter and the single-stage isolation bidirectional charge-discharge converter which are connected in series and simultaneously supply power are connected in parallel and are equivalent to the parallel superposition of two current sources; the method comprises the steps that 1, 2, … and n paths of input source output currents are subjected to error amplification with 1, 2, … and n paths of input source maximum power point reference currents respectively, the 1 st, 2, … and n paths of error amplification signals are multiplied by sinusoidal synchronous signals and then are intersected with the same high-frequency carrier signal respectively to generate 1 st, 2 nd, … and n paths of signals to control an n path of input inverter, the n path of input inverter outputs filtering inductive currents which are in the same frequency and the same phase as output voltages and outputs active power, and SPWM signals are generated by the intersection of the error amplification signals of the system output voltages and the reference voltages and the high-frequency carrier signals to control the output filtering inductive currents and the system output voltages of the charge-discharge converter, wherein phase differences theta and different phase differences theta mean that active power with different magnitudes and directions are output; when the load power is equal to the sum of the maximum powers of the n input sources, theta is equal to 90 degrees, the active power output by the charging and discharging converter is zero, when the load power is larger than the sum of the maximum powers of the n input sources, the output voltage is reduced, theta is smaller than 90 degrees, the charging and discharging converter outputs the active power, namely the insufficient power required by the load by the energy storage device, when the load power is smaller than the sum of the maximum powers of the n input sources, the output voltage is increased, theta is larger than 90 degrees, and the charging and discharging converter outputs the negative active power, namely the residual power output by the n input sources to charge the.

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