Two-motor driving type cascading multi-level inverter system without active front end and control method thereof

The invention discloses a two-motor driving type cascading multi-level inverter system without an active front end and a control method thereof. The system comprises an energy feedback coupling unit arranged between a power unit of a first cascading multi-level inverter and a power unit of a second cascading multi-level inverter, wherein the energy feedback coupling unit comprises a first inverter circuit, a second inverter circuit, a middle direct voltage capacitor, a current reversible chopper circuit, a buffering inductor, a buffering resistor and a storage battery, the current reversible chopper circuit comprises a buck chopper circuit part and a boost chopper circuit part, the switching between the buck chopping mode and the boost chopping mode is achieved according to the voltage between the two ends of the middle direct voltage capacitor, and then energy can be fed back to the storage battery and recycled to drive motors to run. According to the system, a bidirectional transducer based on a three-phase PWM rectifying circuit is not needed, winding remaking of a phase-shifting transformer is avoided, the energy feedback coupling unit does not need to be connected with a power grid, the complexity and cost of the system can be reduced, energy feeding and harmonic wave injection to the power grid are avoided, and the system is suitable for large-scale application.