Active rectifier with current source inverter and voltage source inverter power systems for induction heating and melting applications

A power conversion system, comprising:

• an active rectifier having rectifier transistors;
• a DC link circuit having a DC capacitor coupled to an output of the active rectifier;
• an inverter having inverter transistors and an input coupled to the DC link circuit;
• a resonant tank circuit coupled to an output of the inverter and having an induction heating coil;
• a rectifier controller configured to control the rectifier transistors at a generally constant angle between triggering of the rectifier transistors relative to an AC input phase voltage using sinusoidal pulse width modulation (SPWM) with modulation index (MI) control to control a system output power;
• an inverter controller;
• and
• an input filter coupled to an input of the active rectifier.

An induction heating or melting system, comprising:

• an induction heating coil;
• an active rectifier having rectifier transistors;
• a DC link circuit coupled to an output of the active rectifier;
• an inverter having inverter transistors and an input coupled to the DC link circuit;
• a resonant tank circuit coupled to an output of the inverter and having the induction heating coil;
• a rectifier controller configured to control the rectifier transistors at a generally constant angle between triggering of the rectifier transistors relative to an AC input phase voltage using sinusoidal pulse width modulation (SPWM) with modulation index (MI) control to control a system output power;
• an inverter controller;
• and
• an input filter coupled to an input of the active rectifier.