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  Single-to-Two Series Resonant Electric Furnace We’ve already taken a look at it! How much do you know about it? What’s the working principle behind the inverter section of the series-resonant intermediate-frequency signal furnace power supply? Let’s dive into its manufacturing details together!

1. Power Supply for Series Resonant Induction Furnace

The power supply adjusts its output signal power by varying the frequency of the inverter through its internal control system. As the frequency increases, the operating point moves closer to the resonant point, and the power output steadily rises. Therefore, even a tiny adjustment in frequency can lead to substantial changes in power output. In a series inverter, the load exhibits a rectangular waveform at different voltages, which then transforms into a sinusoidal waveform. This type of inverter can operate either in self-excited mode or in externally excited mode. In this power supply, we adopt the most advanced self-excited series resonant network configuration, enabling 100% successful startup under any real-world operating condition.

2. One-to-two Series Resonant Electric Furnace Power resonant capacitor

In a series resonant inverter circuit, the resonant capacitor primarily serves to provide reactive power, improve the operating circuit voltage, and adjust—or raise or lower—the operating frequency. The capacitor can be cooled by water cooling, using an externally connected circulating water system to cool the capacitor. It is an essential component of the LC series resonant circuit and plays a crucial role in its analysis.

3. Principle of Certain Operations

This circuit employs a special frequency-sweep zero-voltage soft-start method that requires only a mid-frequency current feedback signal, effectively equivalent to both its excitation and self-excitation circuits. The main circuit is simplified, the debugging process is straightforward, and there’s no need for additional starting circuits or pre-magnetization or pre-charge starting procedures.

To begin with the general procedure, first activate the inverter circuit. At the resonant frequency of the first resonant circuit, which is higher than the excitation inverter signal, trigger the thyristor. As the regulator adjusts a given potential from low to high, it controls the operation by scanning the frequency of the preceding series resonant furnace signal—from high to low. When the signal frequency slightly exceeds the resonant frequency of the energy-storage circuit, the medium-frequency voltage begins to build up. The current detection line captures the signal and feeds it back to the inverter, as well as to the automatic frequency-modulation circuit. Before the device enters steady-state operation, the automatic frequency-modulation circuit immediately stops the frequency-driving signal and switches to a low-scan operation, controlled by the reverse rotation of the firing angle regulated by the automatic frequency-change circuit.