Capacitive Power Transfer Field Excitation with an Integrated Resolver for Synchronous Machines

Download or read book Capacitive Power Transfer Field Excitation with an Integrated Resolver for Synchronous Machines written by Marisa Jean Tisler Liben and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Permanent magnet synchronous machines currently dominate traction motor applications such aselectric vehicles. However, wound field synchronous machines offer a comparable alternative in terms of performance and efficiency without the unpredictable prices and high carbon emissions of mining and manufacturing permanent magnets. These machines are ubiquitous at megawatt levels, especially in power plants, but require high-performance, low-cost excitation systems in order to be attractive as traction motors. This work continues research into capacitive power transfer (CPT) as a suitable wireless excitation method for wound field synchronous machines. Here, a capacitive power transfer system is scaled beyond previous work to achieve a > 3X increase in power transfer over previous work by increasing the frequency to > 6.78MHz. A peak output power of 2.3kW at a DCDC efficiency of 88.5% is reached in this system. The system features a minimal part count series tank resonant topology with the inverter redesigned for megahertz level operation with special consideration for stray inductance verified in Ansys Q3D FEA. Likewise, the coupler structure's rectifier is updated to reduce the total parts count by half and handle kilowatt output power with a current-stiff rectifier. The current stiff rectifier features a large DC filter inductor on the output to maintain continuous conduction operation of the diodes. Using SiC Schottky diodes the rectifier has superior performance over conventional voltage-stiff rectifiers to achieve the 2.3kW output power to the load. Additionally, a capacitive resolver is developed to be integrated around the rotating rectifier ofany wireless exciter and also around the CPT coupler boards. This solution reduces the machine cost for traction applications by removing the cost of an external rotor position sensor. The capacitive resolver is made to be a drop-in replacement for conventional magnetic resolvers and compatible with their existing demodulation strategies. The general integrated resolver and rectifier is tested with a digital demodulation kit, AD2S1210 from Analog Devices, and achieves a maximum angle error of 0.3 degrees. The carrier excitation frequency is 20kHz as is standard for magnetic resolvers. For the CPT-integrated resolver and rectifier, the excitation frequency is > 6.78MHz and demodulation with an analog multiplier is used instead. A maximum rotor angle error of 10 degrees is achieved. Overall, the integrated capacitive resolver and rectifier provides an additional pathway to reduce the wound field synchronous machine system cost for adoption in traction applications.