研究目的
To investigate and compare the performance of primary side Pulse Frequency Modulation (PFM) control and secondary side Pulse Width Modulation (PWM) control strategies for achieving Constant Current/Constant Voltage (CC/CV) charging in a Series-Series (SS) Wireless Power Transfer (WPT) system, focusing on efficiency and system complexity.
研究成果
The secondary side PWM control strategy achieves higher efficiency (94%) compared to primary side PFM control (88%) during CC mode with a 35 Ω load, due to operation close to resonant frequency enabling soft switching and reduced conduction losses. PWM control eliminates the need for RF communication, simplifying the system. Both strategies perform similarly in CV mode. The findings suggest that PWM control is more efficient and cost-effective for CC charging in WPT systems, with potential for future development in faster feedback and reduced complexity.
研究不足
The study is based on simulation results using PSIM software, which may not fully capture real-world parasitic effects and practical implementation challenges. The PFM control requires manual tuning of frequency range to prevent instability, and the use of RF communication adds complexity and potential interference. The comparison is limited to a specific 3kW SS WPT system with fixed parameters, and generalization to other topologies or power ratings may require further validation.
1：Experimental Design and Method Selection:
The study employs a simulation-based approach using Power Simulation (PSIM) software to model and analyze a 3kW SS WPT system. Two control strategies are compared: primary side PFM control and secondary side PWM control. The design rationale is based on the gain curve analysis of the SS WPT topology to achieve CC/CV charging modes.
2：Sample Selection and Data Sources:
A 3kW SS WPT system is simulated with parameters including primary inductance (437 μH), secondary inductance (442 μH), mutual inductance (90 μH), coupling coefficient (
3：205), magnetizing inductance (90 μH), turns ratio (
1), primary capacitor (10 nF), secondary capacitor (10 nF), and switching frequency range (83-91 kHz for PFM, 77 kHz for PWM). Data is generated through PSIM simulations under varying load conditions (35 Ω to 160 Ω).
4：List of Experimental Equipment and Materials:
The simulation uses PSIM software for modeling. Components include an inverter, SS resonant tank, rectifier, MOSFET switches, comparators, logic gates, voltage dividers, shunt resistors, and an Analog to Digital Converter (ADC). A Radio Frequency (RF) Transceiver module (nRF24L01+ from Nordic Semiconductor) is mentioned for PFM control feedback.
5：Experimental Procedures and Operational Workflow:
For PFM control, switching frequency is varied between 83-91 kHz using a PI controller with feedback from secondary to primary via RF communication. For PWM control, duty cycle of the active rectifier is adjusted at a fixed switching frequency of 77 kHz using comparators and logic gates without RF communication. Simulations are run for CC and CV modes, with output voltage and current monitored.
6：Data Analysis Methods:
Efficiency is calculated as output power divided by input power. Results are compared through tables and waveforms in PSIM, validating theoretical analyses such as gain curve equations and input impedance calculations.
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