Xiuqin Wei

Design of Class-E Amplifier With MOSFET Linear Gate-to-Drain and Nonlinear Drain-to-Source Capacitances

This paper presents expressions for the waveforms and design equations to satisfy the ZVS/ZDS conditions in the class-E power amplifier, taking into account the MOSFET gate-to-drain linear parasitic capacitance and the drain-to-source nonlinear parasitic capacitance. Expressions are given for power output capability and power conversion efficiency. Design examples are presented along with the PSpice-simulation and experimental waveforms at 2.3 W output power and 4 MHz operating frequency. It is shown from the expressions that the slope of the voltage across the MOSFET gate-to-drain parasitic capacitance during the switch-off state affects the switch-voltage waveform. Therefore, it is necessary to consider the MOSFET gate-to-drain capacitance for achieving the class-E ZVS/ZDS conditions. As a result, the power output capability and the power conversion efficiency are also affected by the MOSFET gate-to-drain capacitance. The waveforms obtained from PSpice simulations and circuit experiments showed the quantitative agreements with the theoretical predictions, which verify the expressions given in this paper.

Waveform Equations, Output Power, and Power Conversion Efficiency for Class-E Inverter Outside Nominal Operation

This paper presents analytical expressions for steady-state waveforms, output power, and power conversion efficiency for the class-E inverter outside the class-E zero-voltage switching and zero-derivative switching conditions. The analytical expressions in this paper include the MOSFET-body-diode effect. By carrying out PSpice simulations and circuit experiments, it is shown that the analytical predictions agree with the simulated and experimental results quantitatively, which indicates the validity of the analytical expressions. Additionally, the switching-pattern distribution maps are also given by using the analytical waveform equations.

Analytical design procedure for resonant inductively coupled wireless power transfer system with class-DE inverter and class-E rectifier

This paper presents a resonant inductive coupling wireless power transfer (RIC-WPT) system with a class-DE and class-E rectifier along with its analytical design procedure. By using the class-DE inverter as a transmitter and the class-E rectifier as a receiver, the designed WPT system can achieve a high power-conversion efficiency because of the class-E ZVS/ZDS conditions satisfied in both the inverter and the rectifier. In the simulation results, the system achieved 79.0 % overall efficiency at 5 W (50 Ω) output power, coupling coefficient 0.072, and 1 MHz operating frequency. Additionally, the simulation results showed good agreement with the design specifications, which indicates the validity of the design procedure.

Design of high-efficiency inductive-coupled wireless power transfer system with class-DE transmitter and class-E rectifier

This paper proposes an inductive coupled wireless power transfer (WPT) system with class-DE transmitter and class-E rectifier along with numerical design procedure. The proposed WPT system can achieve high power-transfer efficiency at high-frequencies because both the transmitter and the rectifier satisfy the class-E ZVS/ZDS conditions. By using numerical design procedure, it is possible to design the WPT system without analysis of the circuit and consideration of the impedance matching. By carrying out the circuit experiment, the validity of the design procedure and effectiveness of the proposed WPT system were confirmed. The laboratory measurement showed the 90.4 % overall power-transfer efficiency with 100 W output at 500 kHz operating frequency.

Analysis and Design of Loosely Inductive Coupled Wireless Power Transfer System Based on Class-

This paper presents a design procedure of high-frequency loosely inductive coupled wireless power transfer (LIC-WPT) system based on class- E2 dc-dc converter, taking into account the power loss reduction of inverter, coupling part, and rectifier simultaneously. Analytical expressions including the dc-to-dc efficiency of the WPT system are derived and the efficiency deterioration mechanism is explained by the circuit model. Through the analytical expressions, the design procedure for satisfying both the class-E switching conditions and power loss reductions at the coupling part is proposed from the circuit-theory viewpoint. The class- E2 WPT system designed by the proposed design procedure achieves high dc-to-dc efficiency at low coupling coefficient, in particular, compared with those designed by the previous design strategies. The validity and effectiveness of the proposed design procedure were confirmed by PSpice simulations and circuit experiments.

{\rm E}^{2}

This paper proposes an inductive coupled wireless power transfer (WPT) system with class-E2 dc-dc converter along with its design procedure. The proposed WPT system can achieve high power-conversion efficiency at high frequencies because it satisfies the class-E zero-voltage switching and zero-derivative-voltage switching conditions on both the inverter and the rectifier. By using the class-E inverter as a transmitter and the class-E rectifier as a receiver, high power-delivery efficiency can be achieved in the designed WPT system. By using a numerical design procedure proposed in the previous work, it is possible to design the WPT system without considering the impedance matching for satisfying the class-E ZVS/ZDS conditions. The experimental results of the design example showed the overall efficiency of 85.1 % at 100 W output power and 200 kHz operating frequency.

DC-DC Converter for Efficiency Enhancement

This paper presents steady-state analytical expressions of the class-D zero-voltage switching inverter at any duty ratio along with a design example. The obtained expressions include stead-state voltage and current waveforms, output power capability, peak switch voltage, peak switch current, output power, and power conversion efficiency as functions of the duty ratio. Additionally, switching-timing allowance due to antiparallel diodes of switching devices can be predicted from the analytical results. The analytical expressions are verified by showing quantitative agreements with PSpice simulations and circuit experiments.

Inductively coupled wireless power transfer with class-E 2 DC-DC converter

This paper presents a numerical locking-range prediction for the injection-locked class-E oscillator using the phase reduction theory (PRT). By applying this method to the injection-locked class-E oscillator designs, which is in the field of electrical engineering, the locking ranges of the oscillator on any injection-signal waveform can be efficiently obtained. The locking ranges obtained from the proposed method quantitatively agreed with those obtained from the simulations and circuit experiments, showing the validity and effectiveness of the locking-range derivation method based on PRT.

Steady-State Analysis and Design of Class-D ZVS Inverter at Any Duty Ratio

This paper presents a resonant inductive coupling wireless power transfer (RIC-WPT) system with a class-E2 dc-dc converter along with its analytical design procedure. By using the class-E inverter as a transmitter and the class-E rectifier as a receiver, the designed WPT system can achieve a high power-conversion efficiency because of the class-E ZVS/ZDS conditions satisfied in both the inverter and the rectifier. In the simulation results, the system achieved 65.9 % overall efficiency at 5 W (50 Ω) output power, coil distance 30 cm, and 5 MHz operating frequency. Additionally, the simulation results showed good agreement with the design specifications, which indicates the validity of the design procedure.

Locking Range Derivations for Injection-Locked Class-E Oscillator Applying Phase Reduction Theory

This paper presents a design procedure for dc-to-dc WPT systems with multiple receivers. For achieving high power-transfer efficiency, the class-E inverter and the class-E rectifiers are applied to the transmitter and the receivers, respectively. By using the numerical design algorithm, we can obtain the accurate component values for achieving the class-E ZVS/ZDS conditions and the impedance matching of the secondary side without system analyses. Additionally, the inductor designs are discussed from the magnetic-component design knowledge [13]. The WPT system with five receivers was designed and circuit experiments were carried out. The power-transfer efficiency was 84.4 % with 5.7 W output power in total.