The Study On The Closed-loop Control Strategy Of Hybrid Two-stage Matrix Converter

As a direct power converter, the Conventional Matrix Converter (short for CMC) has many excellent characteristics, which has caused widespread concern. However, due to the reasons such as complexity of its converter mode and the low maximum transmission ratio, it is limited in the application of industry. Two-stage Matrix Converter (short for TSMC) is a kind of matrix converter with new topology which develops in recent years. It has the advantages of adjustable input power, four-quadrant operation and zero current commutation. Hybrid Two-stage Matrix Converter (short for hybrid TSMC) is a matrix converter with new topology based on two-stage matrix converter, which has more advantages than two-stage matrix converter, it has a higher voltage transfer ratio and can effectively inhibit the unbalanced input voltage and output load disturbances. The closed-loop control strategy of hybrid TSMC this thesis's studies.This thesis firstly introduces the topology structure of hybrid TSMC, analyzes its features and introduced the modulation strategy of hybrid TSMC. Through the rectifier stage and inverter-based control strategy and the H bridge vector modulation transform, we can achieve the purposes like suppress of input imbalance and improving of the voltage transfer ratio. The thesis also establishes the simplified simulation model of hybrid TSMC system. The correctness of the control strategy is verified by the simulation results.When hybrid TSMC adopts open-loop control strategy, although it could improve the inhibition performance of unbalanced input, that under the cases of fluctuation of input and output load voltage perturbation, closed-loop control system is composed by feedforward control, H bridge Converter control and inverter-level closed-loop control, so the system can not maintain stability. Therefore, this thesis proposes a closed-loop control strategy for hybrid TSMC, when the system load disturbance and voltage fluctuation occur; the hybrid TSMC could adjust its level voltage inverter modulation index according to level disturbance to correct the duty cycle of each switch, so the stability of output voltage is ensured. The correctness of closed-loop control strategy is verified by simulation.