A Novel Communication Method Using PWM and Capture Function of DSP for Parallel Controlled Power Electronics Systems

Abstract

Parallel operation by multiple power converters is typical in microgrids. The communication method for parallel control mainly applies MODBUS RTU (Remote Terminal Unit), and the control performance largely depends on the communication speed. This paper proposes a new communication method that enables fast and accurate communication between master and slave systems combined in parallel using the PWM and capture functions of DSP used as the power converter controller. In the proposed communication method, the transmitting side uses the PWM function of DSP to generate a pulse waveform whose pulse width changes according to the reference command and transmits it to the receiving side. Suppose the capture function of the receiving side DSP is set to the time difference rising and falling edge mode. The set event occurs when the capture signal is detected and initializes the counter value to zero. At this time, it detects the counter signal and receives data. We explain the proposed communication method’s principle, characteristics, and noise-canceling method and evaluate the accuracy and stability through data transmission and reception experiments. Finally, three 10kW single-phase electronic loads are connected to the R, S, and T phases to form a three-phase electronic load, and a master and two slaves are designated. The validity of the proposed communication method is verified through the current control response according to the command.

Keywords

• Digital signal processor (DSP)
• electric load
• MODBUS
• power conversion systems
• pulse width modulation (PWM)
• remote terminal unit (RTU)