| Abstract |
A novel method of induction heating has been proposed which requires that a number of coils, supplied by separate inverters of differing frequencies, heata common workpiece. An undesirable mutual inductance exists between each of the. electrically separate coils, the magnitude of which is dependent on coil geometry and the type of workload being heated. This mutual inductance causes a voltage to be induced into the cpils. The freguency of this induced voltage, for a given coil, differs from the frequency of the inverter connected to that coil. This paper describes the investigation of the effects of the induced voltage on the operation of different inverters encountered in high-power induction heating applications. The simulation package, PSPICE, was used to develop models of load-commutated and selfcommutated inverters and simulate the operation of two inverters supplying loads of the type described above. Load-commutated inverters were found to be particularly sensitive to the mutually injected voltage, with commutation failures occurring for quite small values of mutual coupling. Experimental verification of the simulation was obtained using a 300kW selfcommutated inverter and a 450kW load-commutated inverter. |
