Design And Implementation Of High-voltage Soft Starter Inverter Based On Of High Precision Digital Phase Locked Loop

Since the1990s, with the strengthening of people’s awareness of energy saving, high-voltage soft starter inverter has been widely used due to its high reliability and perfect output waveform in the field of high-voltage inverter. In domestic, in the field of high-voltage motor soft starters, it is widely used in the soft starter, including solid state soft starter thyristors, solid state soft starter lowering supplement or liquid resistance soft starters and other devices. Furthermore, because of the environmental issues in the industrial system, it promotes China’s high-voltage inverter industry in a rapid development by the quickly development of new technology and new process.This paper describes the research status of voltage soft starter inverter domestic and abroad. It focuses on the research of design and implementation in the inverter voltage soft starter precision digital phase-locked loop, the main work is as follows:1. It realizes phase shift SVPWM modulation under the vector control system by this design. Firstly, it is analyzed the H-bridge inverter cascade structure, whose output can be converted into the difference between the two-level’s inverter output. The two-level inverter SVPWM is used into the cascaded inverters. Secondly, after obtaining the voltage vector of the first layer cascaded H-bridge inverter generated, it makes the same process of the phase shift in turn to find the voltage vectors generated in the other layers of the H-bridge. Finally, it realizes the vector control based on phase shift SVPWM.2. It proposes an algorithm with high-precision three phase digital phase-locked loop. Frequency tuning mount, superimposed on the inverter output frequencies, is determined by the phase deviation information of the grid and the inverter. It adjusts the inverter output and detects the deviation of phase, frequency, voltage amplitude between the grid and the inverter in real-time. By using Matlab simulation, it achieves a synchronized switching process between the true high voltage inverter and the grid.3. It analyses the impact current and power flow in the different switching situation. It finds the best switching time, and provides the condition and logic of the switching time. The experimental results show that the proposed method avoiding the excessive inrush current in the switching proces, ensuring the peaceful transition of motor speed. It realizes the ’seamless’ switch between the power frequency and the convert frequency.Finally, it summarizes the main results of this paper and makes a prospection.