PURPOSE: To contrive voltage equal to or higher than a predetermined voltage, not to be applied to a load even if the light-receiving quantity of a solar battery is increased, by lowering a modulation degree and keeping AC output voltage constant, when the DC voltage of the solar battery exceeds steady-state voltage.
CONSTITUTION: The DC voltage of a solar battery 1 is PWM-modulated by an inverter bridge circuit 4, and is fed to a motor 3. A modulation degree setting circuit 6 produces a modulation degree setting signal based on the DC voltage, AC output voltage, and speed reference signal from a speed reference circuit 5. An inverter control circuit 7, controls the inverter bridge circuit 4 for operation at a moduration degree according to the modulation degree setting signal and at a frequency according to the speed reference signal. Even if the light- receiving quantity of the solar battery 1 is increased and the DC voltage exceeds steady-state voltage, the modulation degree is set so that the AC voltage to the motor 3 cannot exceed rated voltage.
HAZAMAGUCHI ETSUO
WATANABE NARIAKI
| JPS60200797A | 1985-10-11 |