Single-stage multi-input forward DC-DC chopper type high-frequency link's inverter with series simultaneous power supply

A single-stage multi-input forward DC-DC chopper type high-frequency link's inverter with series simultaneous power supply, comprising:

• a plurality of input filters connected to a non-common ground;
• and a common output filter circuit connected to the plurality of input filters by a multi-input single-output combined isolated bidirectional forward DC-DC chopper;
• each input end of the multi-input single-output combined isolated bidirectional forward DC-DC chopper is connected to an output end of each input filter in a one-to-one correspondence;
• an output end of the multi-input single-output combined isolated bidirectional forward DC-DC chopper is connected to the output filter circuit;
• the multi-input single-output combined isolated bidirectional forward DC-DC chopper comprises a multi-path series simultaneous select power switch circuit, wherein output ends of the multi-path series simultaneous select power switch circuit are connected in inward series, and a single-input single-output combined isolated bidirectional forward DC-DC chopper, wherein the multi-path series simultaneous select power switch circuit and the single-input single-output combined isolated bidirectional forward DC-DC chopper are successively connected in cascade;
• each path of the series simultaneous select power switch circuit of the multi-path series simultaneous select power switch circuit comprises a two-quadrant power switch configured to withstand a unidirectional voltage stress and a bidirectional current stress and a power diode, and a source electrode of the two-quadrant power switch is connected to a cathode of the power diode;
• a drain electrode of the two-quadrant power switch and an anode of the power diode are respectively a positive input end and a negative input end of the series simultaneous select power switch circuit;
• the source electrode of the two-quadrant power switch and the anode of the power diode are respectively a positive output end and a negative output end of the series simultaneous select power switch circuit;
• the single-input single-output combined isolated bidirectional forward DC-DC chopper comprises two identical isolated bidirectional forward DC-DC choppers for outputting respectively a low-frequency positive half cycle unipolar pulse width modulated voltage wave and a low-frequency negative half cycle unipolar pulse width modulated voltage wave, wherein input ends of the two identical isolated bidirectional forward DC-DC choppers are connected in parallel and output ends of the two isolated bidirectional forward DC-DC choppers are connected in series-opposing connection;
• two non-series output ends of the two isolated bidirectional forward DC-DC choppers are the output end of the multi-input single-output combined isolated bidirectional forward DC-DC chopper;
• each the isolated bidirectional forward DC-DC chopper of the two isolated bidirectional forward DC-DC choppers comprises a two-quadrant high-frequency inverter switch, a high-frequency transformer, and a high-frequency rectifier formed by a two-quadrant high-frequency power switch for rectification, freewheeling and polarity selection successively connected in cascade;
• output ends of each of the two isolated bidirectional forward DC-DC choppers are connected in parallel to an active clamp circuit to suppress a voltage spike of a high-frequency rectifier power switch, wherein the active clamp circuit is composed of a clamp switch and a clamp capacitor;
• the output filter circuit comprises a filter inductor and a filter capacitor successively connected in cascade, or comprises a filter inductor, a filter capacitor, and a filter inductor successively connected in cascade;
• the two identical isolated bidirectional forward DC-DC choppers operate in turn for half a low-frequency cycle in a low-frequency output voltage cycle, a first isolated bidirectional forward DC-DC chopper of the two identical isolated bidirectional forward DC-DC choppers operates to output a low-frequency half cycle, a second isolated bidirectional forward DC-DC chopper of the two identical isolated bidirectional forward DC-DC choppers stops working, and the two-quadrant power switch for a polarity selection is turned on;
• a high-frequency inverter switch in the multi-input single-output combined isolated bidirectional forward DC-DC chopper of the single-stage multi-input forward DC-DC chopper type high-frequency link's inverter modulates multi-path input DC voltage sources Ui1, Ui2, . . . , Uin into bipolar three-state multi-level SPWM voltage waves;
• the bipolar three-state multi-level SPWM voltage waves are isolated by the high-frequency transformer and are rectified by the high-frequency rectifier into unipolar three-state multi-level SPWM voltage waves, to obtain a high-quality sinusoidal AC voltage or a sinusoidal AC on a single-phase AC passive load or a single-phase AC grid after being filtered by an output LC filter;
• when an energy is transferring forward, an amplitude of the bipolar three-state multi-level SPWM voltage waves is ±(Ui1+Ui2+ . . . +Uin)N2/N1, ±(Ui1+Ui2+ . . . +Uin−1)N2/N1, . . . , ±Ui1N2/N1, an amplitude of the unipolar three-state multi-level SPWM voltage waves is (Ui1+Ui2+ . . . +Uin) N2/N1, (Ui1+Ui2+ . . . +Uin−1) N2/N1, . . . , Ui1N2/N1, wherein n represents a path number of a plurality of input sources, N1 and N2 represent turns of a primary winding of the high-frequency transformer and turns of a secondary winding of the high-frequency transformer, respectively;
• n is a natural number greater than 1;
• a relationship between an output voltage uo and the multi-path input DC voltage sources, a turns ratio N2/N1 of the high-frequency transformer, and duty cycles d1, d2, . . . , dn of multi-path series simultaneous select power switches Ss1, Ss2, . . . , Ssn is uo=(d1Ui1+d2Ui2+ . . . +dnUin) N2/N1;
• a circuit topology of the single-stage multi-input forward DC-DC chopper type high-frequency link's inverter with series simultaneous power supply comprises a single-transistor forward DC-DC chopper type circuit, a push-pull full-wave DC-DC chopper type circuit, a push-pull bridge DC-DC chopper type circuit, a push-pull forward full-wave DC-DC chopper type circuit, a push-pull forward bridge DC-DC chopper type circuit, a double-transistor forward DC-DC chopper type circuit, a half-bridge full-wave DC-DC chopper type circuit, a half-bridge DC-DC chopper type circuit, a full-bridge full-wave DC-DC chopper type circuit, and a full-bridge DC-DC chopper type circuit the double-transistor forward DC-DC chopper type circuit is composed of n+8 two-quadrant high-frequency power switches configured to withstand the unidirectional voltage stress and the bidirectional current stress, and n+4 diodes;
• the single-transistor forward DC-DC chopper type circuit is composed of n+6 two-quadrant high-frequency power switches configured to withstand the unidirectional voltage stress and the bidirectional current stress and n diodes;
• the push-pull full-wave DC-DC chopper type circuit is composed of n+8 two-quadrant high-frequency power switches configured to withstand the unidirectional voltage stress and the bidirectional current stress and n diodes;
• the push-pull bridge DC-DC chopper type circuit is composed of n+12 two-quadrant high-frequency power switches configured to withstand the unidirectional voltage stress and the bidirectional current stress and n diodes;
• the push-pull forward full-wave DC-DC chopper type circuit is composed of n+8 two-quadrant high-frequency power switches configured to withstand the unidirectional voltage stress and the bidirectional current stress and n diodes;
• the push-pull forward bridge DC-DC chopper type circuit is composed of n+12 two-quadrant high-frequency power switches configured to withstand the unidirectional voltage stress and the bidirectional current stress and n diodes;
• the half-bridge full-wave DC-DC chopper type circuit is composed of n+8 two-quadrant high-frequency power switches configured to withstand the unidirectional voltage stress and the bidirectional current stress and n diodes;
• the half-bridge DC-DC chopper type circuit is composed of n+12 two-quadrant high-frequency power switches configured to withstand the unidirectional voltage stress and the bidirectional current stress and n diodes;
• the full-bridge full-wave DC-DC chopper type circuit is composed of n+12 two-quadrant high-frequency power switches configured to withstand the unidirectional voltage stress and the bidirectional current stress and n diodes;
• and the full-bridge DC-DC chopper type circuit is composed of n+16 two-quadrant high-frequency power switches configured to withstand the unidirectional voltage stress and the bidirectional current stress and n diodes;
• an independent power supply system formed by the single-stage multi-input forward DC-DC chopper type high-frequency link's inverter with series simultaneous power supply employs an energy management control strategy of the output voltage and input current instantaneous value SPWM master-slave power distribution, wherein an output power of the 1st, 2nd, . . . , (n−1)th path input sources is fixed and the nth path input source supplies insufficient power needed by a load;
• a grid-connected power supply system formed by the single-stage multi-input forward DC-DC chopper type high-frequency link's inverter with series simultaneous power supply employs an energy management control strategy of an input current instantaneous value SPWM maximum power output of the 1st, 2nd, . . . , nth path input sources;
• the single-stage multi-input forward DC-DC chopper type high-frequency link's inverter with series simultaneous power supply inverts a plurality of unstable input DC voltages connected to the non-common ground into a stable and high-quality output AC needed by the load, the plurality of input sources all supply power to an output AC load in a high-frequency switching period, and the plurality of input sources are connected in series to simultaneously supply power to the output AC load in the high-frequency switching period.