A large-capacity pulsewidth modulated (PWM)-controlled uninterruptible power supply (UPS) with insulated gate bipolar transistors (IGBTs) in parallel in the inverter units is described. The proposed repetitive learning and current feedforward control system provides two to ten times better steady-state and transient characteristics than a conventional instantaneous control alone Author(s) Ohshima, H. Toshiba Corp., Tokyo, Japan Kawakami, K.