Fundamental Research on Control Method for Power Conversion Circuit of Wireless In‐Wheel Motor Using Magnetic Resonance Coupling

Abstract

SUMMARYThe in-wheel motor (IWM) is the most preferred driving mechanism of electric vehicles for its advantages of vehicle motion control, energy efficiency, and vehicle design flexibility. One of the technical problems of the IWM is the reliability of power and the signal wires. Wireless power transfer technology is the best solution to this problem. In this paper, a bidirectional wireless power transfer circuit using a primary inverter and a secondary converter is proposed. We propose a control method for both the inverter and the converter to stabilize the secondary dc-link voltage. The proposed method is verified by simulation and experiment using simulated test equipment. C⃝

Novel Transmitting Power Control Method without Signal Communication for Wireless Power Transfer via Magnetic Resonance Coupling

“…When load is approximated by pure resistance, the secondary voltage and current at the resonance angular frequency are leading by 90° with respect to primary voltage . Thus, assuming that v 21 is leading by 90° with respect to v 11 , the effective values of primary current ( I 11 ) and of secondary current ( I 21 ) can be expressed in the following way: where V 11 and V 21 are the effective values of v 11 and v 21 , respectively.…”

“…In actual circuits, output voltage of primary inverter and input voltage of secondary ac-dc converter present square waveforms. However, SS-compensated magnetic resonance coupling has a bandpass filter characteristic [13], and it is just necessary to analyze only fundamental wave characteristic when operating frequency is equal to resonance frequency. Therefore, the circuit in Fig.…”

“…In order to control the power transmitted to load, the secondary ac-dc converter has to be appropriately operated [ 16]. Synchronous PWM rectification scheme in which switching is synchronized to i 21 [13] and two-mode scheme in which operation modes are switched asynchronously [16] were proposed for switching operation. The latter is adopted in this study.…”

“…In the case of W-IWM, there is no battery or other power source on the secondary side, and power is transmitted to inverter to drive a permanent magnet synchronous motor. That is, the load has a constant power characteristic, and the load voltage is unstable, which requires transmitted power control on secondary side [13]. We proposed a control method using a feedforward controller on primary side and a feedback controller on secondary side [13].…”

“…That is, the load has a constant power characteristic, and the load voltage is unstable, which requires transmitted power control on secondary side [13]. We proposed a control method using a feedforward controller on primary side and a feedback controller on secondary side [13]. However, the problem is that the required power cannot be satisfied by control only on the secondary side when the power transmitted from the primary side becomes deficient due to variation of coupling coefficient between transmitting and receiving coils, errors in resonance frequency and operating frequency, communication delays, modeling errors, and other factors.…”