Software Design for MMC Sub-Module Voltage Acquisition Based on Zynq

In response to the increasing number of sub-modules and the growing complexity of the MMC system, the simplification of controller architecture and the precision of sub-module parameter acquisition are of significant importance in engineering. This paper presents a design scheme for replacing the traditional DSP-based MMC main controller with one based on Zynq, along with an approach to enhance the accuracy of sub-module capacitor voltage acquisition by improving the PWM duty cycle measurement method. Firstly, the operational principles of submodules and the conventional controller structure are elucidated. Subsequently, a solution is proposed that employs a single FPGA to serve as both the main controller and the sub-module controller. This solution involves the design of a PWM generation circuit and a novel duty cycle measurement method. Finally, through simulation and comparison of various duty cycle measurement algorithms, an applicable measurement method for sub-module capacitor voltage acquisition is proposed. The deployment of this measurement method on a Zynq development board validates its rationality and feasibility.