Tripless control method for general-purpose inverters

The control method described prevents general-purpose inverters without current regulators from tripping easily, i.e. to be tripless no matter how their load is varied, and enables motors to rotate stably at high frequencies. It uses only current sensors and is a combination of pulse-width-modulated (PWM) control and torque control. The PWM control changes an asynchronized mode to a synchronized mode when the modulation ratio becomes more than one, enabling the carrier wave frequency to be continuously varied with the inverter frequency so that motors can rotate stably over a wide frequency range. The torque control uses a real and reactive component detector, magnetic flux compensator, slip compensator, and current limit controller. Experiments prove that this tripless control can be satisfactorily applied to general-purpose inverters