Patent ID: 7692333

Claim:
A method for controlling an adjustable speed drive system for a primary loop recirculation pump, having an adjustable speed drive systems provided with a first breaker connected to a high voltage bus of unit auxiliary power supply system, an inverter connected to the first breaker via a transformer, a second breaker connected to an output side of the inverter, a gate driver that supplies a gate pulse to the inverter, and an inverter control portion that drives the gate driver; the adjustable speed drive system being combined with a system of a backup adjustable speed drive system, the method comprising the steps of when a malfunction detection portion detects a malfunction in a main adjustable speed drive circuit portion including the inverter and the gate driver in the adjustable speed drive system used in a normal operation, switching the main adjustable speed drive circuit portion to the backup adjustable speed drive system, and continuing an operation of a recirculation pump motor for driving a recirculation pump that controls a flow of a reactor core.