Abstract: A static power supply for converting DC power from a source to AC power at relatively high frequencies in a load. The static power supply is particularly useful for supplying power to induction heating loads operating at frequencies of 10 kHz. and higher. The DC supply is connected to supply substantially constant current to a controlled rectifier switching circuit. The controlled rectifiers are gated to produce alternating current in a commutating capacitor. The DC supply and switching circuit are connected to the load via a blocking capacitor so that the AC current component in the switching circuit appears as high frequency AC load current. The circuit arrangement imposes low operating stress levels on the controlled rectifiers, and provides a circuit turn-off time that is relatively independent of load.

Abstract: A constant voltage, constant frequency, uninterruptible a.c. power supply having a line voltage regulator, a rectifier-inverter with an emergency battery power supply and a transfer switch for selectively connecting the line voltage regulator and rectifier-inverter to a load. Under normal conditions, the line voltage regulator and rectifier inverter derive their operating power from the power line and are both connected to the load. If the fault detection system detects a power line fault, it causes the transfer switch to disconnect the line voltage regulator from the load and the rectifier-inverter supplies power to the load from the emergency battery power supply. If the fault detection system detects a rectifier-inverter fault, it causes the transfer switch to disconnect the rectifier-inverter from the load. A synchronization control system regulates the phase of the rectifier-inverter.