Research on parallel multiple bidirectional converters with power quality control function

At present, many articles have studied the three-phase PWM bidirectional converter, which is one of the research focuses of grid connected converter. It can be used as SVG or APF to control reactive power and harmonic of power grid. In a DC charging station for electric vehicles, when multiple PWM bidirectional converter modules are connected in parallel to work on the same AC bus, some modules may have DC loads, while others may be unloaded. The traditional approach is to let the unloaded modules exit operation, while the loaded modules only undergo rectification. This approach does not make good use of bidirectional converters for power quality management, nor does it utilize parallel multiplication to improve output characteristics. Therefore, this article studies a system in which all modules, regardless of whether they are loaded or not, do not need to exit operation. When there is a load, the inverter module rectifies to provide energy to the DC side. When there is no load, the inverter module continues to maintain voltage. The presence or absence of a load does not affect the module's participation in managing the reactive current and harmonic current of the power grid. Modules with the same load state use CPS-SPWM to reduce output harmonics. This paper presents the control method of this parallel multiple converters, and the simulation experiment proves the feasibility of the method.