Induction heater circuit protection closed loop control process

摘要

A closed loop protection system for an induction heater responds to detection of: voltage spikes in, an oscillation frequency characteristic of, rapid surges in power supply current drawn by, and excess power supply current drawn by a high frequency generator of the heater system; and in response to detecting any of these sends feedback to a control subsystem to limit voltage or current of the generator. The closed-loop control process can protect the induction heater circuits using actions including: temporary shut-down, fast active limiting of supply current and fast active limiting of internal high voltages, in dependence on the abnormal circuit conditions that arise and are detected. The protective actions are effected before the abnormal circuit conditions can develop to damaging levels and can also alert the user to the existence of an abnormal condition, by an indicator device or by affecting the behaviour of the induction heater, so that action can be taken to deal with the originating problem.