Cascade type time-interval variable-order multi-level static converter

The invention provides a cascade type time-interval variable-order multi-level static converter, which can be modularized; a previous-stage four-way isolation DC-DC (Direct-Current-Direct-Current) converter (1) is connected to a subsequent-stage four-unit cascade inverter (2); a novel time-interval variable-order multi-level control circuit (3) is connected between the previous stage and the subsequent stage; the converter is characterized in that the previous stage is adopted with four ways of mutually independent, staggered and parallel double-tube forward direct-current converters; the subsequent stage is a cascade structure composed of four single-phase H bridges; a carrier phase-shifting frequency-doubling SPWM (Sinusoidal Pulse Width Modulation) technology is adopted; the time-interval variable-order multi-level control circuit is connected between the previous stage and the subsequent stage; the previous stage of the static converter is beneficial to reducing input current ripple and reducing the volume of a filter; the subsequent stage is low in voltage stress of a power switch device, high in circuit modularization degree and low in loss; and, by means of the time-interval variable-order multi-level control circuit, on the premise of not increasing the number of independent sources of the previous stage, the more level number of output can be realized, and the THD (Total Harmonic Distortion) of the harmonic wave is low.