Hybrid multilevel converter and variable switching frequency trajectory optimization control method thereof

Abstract

The invention discloses a hybrid multilevel converter and a variable switching frequency trajectory optimization control method thereof. The hybrid multilevel converter is connected between a direct current power grid and a three-phase alternating current power grid. The variable switching frequency trajectory optimization control method of the hybrid multilevel converter comprises the following steps that S1, differential equation models of the hybrid multilevel converter are established; S2, discretization state equations from the (K+1)th step to the (K+delta)th step are deduced; S3, a feasible sampling point set of output current predicted values is determined; S4, the optimal value f<theta> of an objective function f<theta>(k) is obtained, a switching function vector S<theta,opt>[k] corresponding to a feasible predicted position is used as a kth-step switching signal of the hybrid multilevel converter, data loading of a digital signal processor is completed, and a PWM switching signal is sent out at the moment corresponding to the optimal predicated position of a current trajectory. According to the hybrid multilevel converter and the variable switching frequency trajectory optimization control method of the hybrid multilevel converter, submodule direct current bus capacitance and voltage stable control of all full-bridge inverters and all half-bridge inverters of an upper bridge arm and a lower bridge arm can be achieved, rapid trajectory tracking of a current on the alternating current side can be achieved, and variable switching frequency optimization control can be achieved.

Description

technical field [0001] The invention belongs to the technical field of power electronic converter control and flexible power transmission and distribution of power systems, and relates to the control technology of hybrid multilevel converters, in particular to a hybrid multilevel converter and its variable switching frequency track optimization Control Method. Background technique [0002] The rapid development of power electronic devices and digital signal processors provides a broad development space for the practical application of high-performance power conversion and control devices. The power electronic converter topology has experienced the traditional two-level converter, neutral point clamp Bit type (NPC) three-level converters, and several stages of multi-level power electronic converters. The multi-level power electronic converter adopts the series and parallel connection of power electronic devices or basic conversion circuits, which significantly improves the w...

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Problems solved by technology

[0006] Another object of the present invention is to provide a control method by introducing a variable switching frequency track optimization control method to overcome the difficulty of controller design in traditional control methods, difficulty in coordinating voltage controller and current controller parameters, fixed switching frequency and large switching loss Shortcomings

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