FREQUENCY CONVERTER WITH OFF-LINE INDUCTOR Russian patent published in 2007 - IPC H02M5/44 

FIELD: converter engineering; power supplies for off-line induction heaters.

SUBSTANCE: proposed frequency converter depends for its operation on some characteristic features. Basic one is that its time characteristic is shaped and its power characteristics are optimized not under current resonance conditions but due to separate generation of control signal active phase length optimal for given induction heater and load within which inductance coil (inductor with heated metal) is charged to desired current and further due to length of self-inductance emf occurring upon cutoff of inverter diodes and discharge-time dictating inductor. These two tightly interrelated sequential phases of converter-generated exponential-waveform DC pulses are time-setting components optimal from power standpoint which, as a whole, dictate pulse repetition rate automatically varying with inductor parameters. Another important characteristic feature of proposed frequency converter is actually non-inertial protection of inverter controlled diodes against load (inductor) short-circuit, inductor protection against turn-to-turn fault, overcurrent protection of rectifier, that is, protective gear of proposed frequency converter depends for its operation not only on analysis of control signal condition but primarily on response of entire system to condition of most expensive components (controlled diodes, rectifier, and inductor). So, proposed device is essentially closed-circuit system for shaping time characteristic and, consequently, for optimizing power characteristics of off-line induction heaters automatically adapted to varying load parameters.

EFFECT: enhanced operating reliability, safety, and efficiency, simplified design of device.

3 cl, 11 dwg