An efficient braking method for controlled AC drives with a diode rectifier front end

Standard pulsewidth-modulated inverter-fed induction motor drives employ a diode rectifier bridge to supply ac power from the utility to the de link. Although a diode rectifier is the most cost-effective solution, it does not permit reversing the power flow. This prohibits operating the machine in t he regenerative braking mode for active deceleration. An innovative control method substitutes conventional hardware, such as an active front-end rect ifier or a chopper controlled braking resistor in the dc-link circuit, by a dditional software that is implemented in the standard microprocessor contr ol. The control algorithm maximizes the power losses in the machine and in the inverter. It enables regenerative braking operation of the induction mo tor at high torque. The algorithm conserves the high dynamic performance of a vector-controlled drive system.