Patent ID: 8786225
Filing Date: 2014-07-22
Classification: H02P

Abstract:
1. An inverter power generator comprising: a prime mover; a synchronous motor coupled with the prime mover, wherein the prime mover is configured to rotate the synchronous motor to generate AC power; a converter connected to the synchronous motor, the converter configured to convert the AC power from the synchronous motor into DC power; an inverter connected to the converter, the inverter configured to invert the DC power from the converter into AC power of a required frequency; and a capacitor arranged between the converter and the inverter, wherein: the converter includes a current controller configured to set a current limit ratio according to a rotation speed of the synchronous motor and to limit a converter current according to the current limit ratio; and the current controller is configured to set the current limit ratio lower than 100% when the synchronous motor is at a predetermined rotation speed lower than a rated rotation speed and linearly increase the current limit ratio up to 100% according to an increase in the rotational speed of the synchronous motor, wherein: the converter includes a current command generator configured to generate a current command value according to a difference between a set PN voltage value serving as a voltage command value to charge the capacitor and a feedback PN voltage value from the capacitor; the current controller includes: a current limiter that is connected after the current command generator, the current limiter including a current limit ratio table indicating a relationship between rotation speed of the synchronous motor and current limit ratio, the current limiter configured to determine a current limit ratio according to a given rotation speed of the synchronous motor and the current limit ratio table and limit the current command value of the current command generator with the determined current limit ratio; and a current driver configured to control an output current according to the limited current command value from the current limiter; and the current limit ratio table is configured to specify a current limit ratio lower than 100% if the synchronous motor is at the predetermined rotation speed lower than the rated rotational speed and linearly increase the current limit ratio up to 100% according to an increase in the rotational speed of the synchronous motor.