2results about How to "Improve harmonic characteristics" patented technology

The invention discloses an H-bridge low-frequency switch control method of a cascaded half-bridge converter, which is characterized in that a direct-current side adopts an in-phase carrier laminated modulation strategy, zero level duration is increased at a signal zero crossing point, the action times of a direct-current side switching device near the zero crossing point are reduced, and the switching loss of an H-bridge under closed-loop control is effectively inhibited. An alternating current side phase control algorithm is provided for multiple bridge arms, the bridge arms are divided into a leading group and a lagging group, control signals of sub-modules are redistributed based on fundamental wave phases, meanwhile, two groups of phase-complementary power frequency control signals are distributed for H bridges of the bridge arms, and on the premise that the output characteristics of the converter are not affected, the control signals of the sub-modules are distributed to the H bridges of the bridge arms. All H-bridge switching tubes only act twice in a fundamental wave period, strict power frequency switching and zero voltage switching are achieved, and switching loss is reduced to the minimum. And meanwhile, a battery online energy balancing function based on SOC sorting is integrated, so that the reliability of the converter is improved and the service life of the converter is prolonged on the premise of keeping relatively high output waveform quality, and the switching frequency of an H bridge under closed-loop control is reduced.

The present application belongs to the field of rail transit conversion technology application, and particularly relates to a novel multi-topology conversion inverter and a control method thereof. The present application solves the technical problem that the basic main circuit topology structure of the three-phase inverter is determined in the design, and cannot be changed according to the actual situation or working condition. When a switching device in the power module is damaged, the three-phase inverter has to be stopped, resulting in power loss, and having a great influence on the reliability and operation efficiency of the locomotive. The present application optimizes the design of the three-phase inverter main topology, adopts modular design, reduces the types of power modules, reduces the inventory of spare parts, and the main topology structure of the three-phase inverter can be flexibly changed according to the demand. When a switching device is damaged, the normal operation of the three-phase inverter can still be realized through topology switching. The present application is redundantly designed for different application environments and application requirements, and improves the reliability and operation efficiency of the three-phase inverter.