Researches On Asymmetrical PWM Control Method’s Application In Contactless Inductive Power Transfer System

The technology of Contactless Inductive Power Transfer, which belongs to the field of smart grid, has achieved the energy transfer between the electrical equipment and power lines without physical contact. Compared with the traditional power transfer technology, this technology can avoid spark and mechanical swear, so it has a bright future in the certain domains including explosive environment, underwater environment as well as medical field. So it has both theoretical significance and practical values to research the Contactless Inductive Power Transfer Technology. The main work in this dissertation:1. Investigate the main application areas of CIPT technology, and then introduce the prospect as well as research status of CIPT technology, at the same time, this chapter analyzes the key technologies and possible problems of this technology.2. Without changing the topology of resonant power converter, this paperproposes generalized modulation control strategy for H-bridge resonant converter. Then this chapter analyzes the generalized modulation control method of CIPT output power control, and then proposes the asymmetrical PWM modulation based on the analysis of ZVS soft-switching technology. Then we build an equivalent circuit model of CIPT system to realize the advantages of ZVS soft-switching, so that we can lay a theoretical foundation for analysis and optimize of voltage-CIPT system.3. The coupling coefficient between the former and vice magnetic coils of voltage CIPT system is relatively low, and the active power absorbed by the load is low, both of these lead to a low efficiency of the power converter. This paper studies the voltage type CIPT system those primary and secondary sides are series resonant, and then builds an established analytical equivalent circuit model combined with the steady-state CIPT system. By using the asymmetrical PWM modulation method, we can increase the safety and reliability of CIPT system. Based on the analysis of simulation result, this paper can provides a theoretical reference for the design and study of voltage-CIPT system.4. Through theoretical analysis coupled with repeat experimental testing, the influence of control method on the CIPT system operating Characteristics including: smooth the power flow, restrain system shock, decrease workstress of power devices as well as the EMI of power switching devices when the power delivered changes. To solve the problems mentioned above, this paper proposes a new modulation drive control method while does not change the topology of former resonant power inverter, so the power control can be optimized and both the safety and the reliability of CIPT system can be increased.5. In order to verify the effectiveness of asymmetrical PWM modulation method, this chapter builds a CIPT system simulation model in the software of Matlab/Simulink. A tentative CIPT system was designed with the mentioned simulation parameters. The switching frequency used in the model is 20 k Hz, and the voltage of DC Bus is 50 V, and the resistor value of simulated load is 10Ω. Observe the output voltage and current of inverter, we can draw the conclusion that the design of CIPT system using asymmetrical PWM modulation method is feasible, and both the parameter and the control method are reliable. The platform of this simulation model lays a solid technical foundation for in-depth study CIPT.