Research On Optimized Control Strategy In Three-level Active Neutral Point Clamped Inverter

With the development of power electronic technology, the requirements of inverter capacity and switch frequency have been improved. Multi-level inverter with its good quality of output voltage waveforms, low harmonic distortion rate and higher efficiency has been widely used in high voltage and high power applications. Based on the study of existing PWM algorithm for the Active Neutral-Point-Clamped (ANPC) inverter, PWM method, Neutral-Point Potential (NP) balancing, Common-Mode Voltage (CMV) and loss distribution are studied in this paper. The main content of this paper as follows:1. Based on the relationship between SHEPWM and SVPWM, a novel control strategy of the NP balancing for three-level ANPC using SHEPWM is-presented, which leads to effectively control the NP balancing and not affect the line-to-line voltage and their harmonic spectrums.2. The output waveform of three-phase SHEPWM can be regarded as the corresponding space vectors. A novel control strategy of reducing the maximum amplitude of the CMV for three-phase three level ANPC converter is presented.3. Base on the above research, a control strategy of the NP balancing and the CMV suppression is presented.4. The mathematical model of three-level ANPC inverter loss is established. The working states and loss distribution balancing method are analysed in this paper.5. A three-level ANPC simulation platform and experimention platform are set up. The simulation and experimental results are provided to verify the the validity of the above control strategies.