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Category: Power Technology |
Medium frequency furnaces are divided into two types according to the compensation form: parallel resonant (current type) medium frequency furnaces and series resonant (voltage type) medium frequency furnaces. So what is medium frequency furnace series resonance? What does the medium frequency furnace series resonant control board look like?
The inverter used in the series resonant medium frequency furnace is a series resonant inverter, and its load is a series resonant load. Usually, a voltage source is required for power supply. In the medium frequency furnace, the voltage source is usually composed of a rectifier plus a large capacitor. Due to the large capacitance, the input voltage of the inverter can be approximately considered constant. By alternately turning on and off the controllable devices on the inverter, an alternating square wave voltage can be obtained at the output end of the inverter. Its voltage amplitude depends on the input voltage value of the inverter, and the frequency depends on the switching frequency of the devices.
The implementation process of power control is as follows: the product of the inverter input voltage Ud and current Id is compared with the set value, and the difference is input to the power regulator. Then its output is compared with the current Id. After calculation by the current regulator, it controls the output pulse frequency of the voltage-controlled oscillator, so that the overflow pulse time of the counter changes, thereby changing the trigger pulse frequency of the thyristor, thus achieving the expected control effect. This control effect of the medium frequency furnace series resonant control board is reflected in maintaining the input power of the furnace constant under heavy load conditions above the rated parameters of the furnace; within the light load range below the rated value, it controls the output current within the limit value.
