Induction heating circuit for cooking ring - includes filter to prevent return of high frequency pulses to mains supply and semiconductor switch

摘要

The inductive heating circuit for a cooking ring includes a filter (F) connected to the 50 Hz supply terminals. The filter allows energy at 50 Hz to pass but prevents the transmission of high frequency pulses back into the mains network. The filter consists of a pi-element comprising two capacitors (C1,C2) and an inductance (L1). This filter is connected to a rectifier bridge (pi), the output of which is applied in parallel to a potential divider (R12,R19) and an oscillator circuit including a controlled semiconductor switch. Control circuits, deriving power from the potential divider, switch the semiconductor at high frequency to drive the oscillating circuit. This includes a heating inductance (L2), capacitor (C3) and variable inductance (Trl) to control the power delivered.