Load Resonant Circuit Research Articles

Automatic Calculation Method of Load Resonant Frequency of Photovoltaic Power Supply

The resonance phenomenon of photovoltaic power supply load makes the output voltage of grid-connected photovoltaic power supply system difficult to keep stable, which brings trouble to power supply. Therefore, it is necessary to study the automatic calculation method of load resonance frequency of photovoltaic power supply, so as to detect the load resonance frequency of photovoltaic power supply in real time, thereby ensuring the normal operation of photovoltaic power supply system. The load resonance frequency of photovoltaic power supply is divided into steady-state load resonance frequency and dynamic load resonance frequency. The mathematical model of load resonant circuit of photovoltaic power supply is established by calculating algorithm of load resonant frequency of photovoltaic power supply in steady state, and load resonant frequency of photovoltaic power supply in steady state is calculated. The resonance detection algorithm based on wavelet transform and Hilbert-Huang transform is used to analyze and calculate the load resonance frequency after detecting the resonance signal of photovoltaic power system. The experimental results show that the resonant frequency of photovoltaic power supply load calculated by this method is not much different from the actual resonant frequency of photovoltaic power supply load, and the error range is between-0.30% and 0.49%. Therefore, this method can keep the load resonance frequency of the photovoltaic power supply the same as the RF transmission resonance frequency, and can ensure the normal operation of the photovoltaic power supply.

Three‐leg inverter configuration for simultaneous dual‐frequency induction hardening with independent control

Parts of certain objects need hardening. Hardening is a heat treatment process which can be achieved by induction heating. Certain objects like gears require alternating source with two different frequencies. Simultaneous application of dual frequencies is desirable for proper hardening of a gear. This study proposes a three-leg inverter topology with a load resonant circuit which can provide independent and simultaneous control of low-frequency (LF) and high-frequency (HF) currents through the load coil. The load circuit is a combination of two series resonant circuits which operates at the desired LF and HF. Power control is achieved with phase modulation and asymmetric duty cycle control techniques. A 240 W prototype of the proposed dual-frequency inverter is implemented and tested. Experimental results obtained are in good agreement with the simulation results.

Single Inverter Configuration for Simultaneous Dual Frequency Induction Hardening with Independent Control

Induction hardening is used to heat and harden different parts of components with different size and shape. Components with non uniform surface like gears require different frequencies, a low frequency to heat inner core and a high frequency to heat the outer surface. It is desirable to apply these low and high frequency currents simultaneously for proper hardening of gear. This paper proposes a single inverter topology with a load resonant circuit with independent and simultaneous control of low and high frequency currents through the load coil. The load circuit is a combination of two series resonant circuits which operates at the desired low and high frequencies. Asymmetric duty cycle control technique is used to achieve power control.

Inverter Configuration for Simultaneous Dual Frequency Induction Hardening with Independent Control

SummaryInduction hardening is a heat treatment process which selectively heats parts of work-piece with different size and shape. Components like gears require different frequencies with inner core requiring low frequency and outer surface requiring high frequency. Simultaneous application of low and high frequency currents is desirable for proper hardening of gear. This paper proposes a two inverter topology with a load resonant circuit which can provide independent and simultaneous control of low and high frequency currents through the load coil. The load circuit is a combination of two series resonant circuits which operates at the desired low and high frequencies. Power control is achieved with phase modulation of low and high frequency inverters.

A high-power-factor DC-linked resonant inverter

A new approach of power-factor correction for the DC-linked high-frequency resonant inverters is proposed. The high-power-factor operation is achieved by altering the energy delivery process of the conventionally used topology. The load resonant circuit of the proposed topology draws a high-frequency pulse current directly from the AC source. This approach can be accomplished merely with an additional small capacitor as the energy buffer and a diode as the energy transfer switch. The design and experimental results for an implementation example are given to verify the theoretical analyses.