Research On Wireless Power Transfer System For Inductive Household Appliances

In recent years, wireless power transfer technology(Wireless Power Transfer, referred WPT) has been a great development, especially in the field of electric vehicles, bio-medical, personal electronic devices, because of its convenience, security, wireless power transmission technology, et c. It has great potential for development and application. This paper mainly researches the wireless power transfer for kitchen appliances load, analyzes the impact of the universal motor which kitchen appliances are often used, and according to the mode that the system works, the control system is analyzed and designed.First, according to the circuit coupling theory, establish a wireless power supply system equivalent circuit model, derive a mathematical expression of relational characteristics and indicators of the system, analyzes the effects of coupling mechanism,circuit parameters, the load on the system parameters such as transmission efficiency, transmission power, and analysis the circuit model that the system uses. Finally, the frequency bifurcation phenomena of the wireless power transfer system is analyzed and discussed about its critical condition.Secondly, anlysises the principle of universal motor and derive the transfer function, uses the finite element method to discuss the main reactance from start to stop, at different speeds, different load, and then(including load start, load start, running with load rated conditions, 10% overload condition running) current, voltage, iron loss, copper loss, output torque, the counter electromotive force at different conditions were simulated. Finally, the impact of the universal motor load on wireless power feeding system is discussed, mainly analysis reflected impedance of different load impedance changes, provide theoretical support for closed-loop control of the subsequent chapters.Mainly introduces closed-loop control of wireless power transfer system,hardware and software design. To make the universal motor work well, and inhibit the situation that mechanical characteristics become "soft", consider adding the control circuit, not only making sure the universal motor work and also having an ability to adapt the coupling coefficient changes, but also taking into account the a smaller volume and other factors in wireless power transfer system. Here we use bang-bang control to maintain contant voltage at the receiving side. For the transmiting side because of using the series coupling structure when the load is suddenly disconnected or moved, electric current of the transmitting side circuit occurs over the stream. Finally, according to the theoretical analysis,build a system which its radius of the receiver coil is 8cm, its radius of the transfer coil is 10 cm, its transmission power is 100 W, its transmission distance is 2cm, its transmission efficiency is 86.6%, make some experiments with this system and get the conclusions.