COMPRESSOR VARIABLE-FREQUENCY SPEED ADJUSTING SYSTEM AND CONTROL METHOD FOR DIRECT-CURRENT BUS VOLTAGE

摘要

A compressor variable-frequency speed adjusting system and a control method for a direct-current bus voltage, comprising: a rectifier module, for converting an alternating-current input voltage into a direct-current bus voltage; an inverter module, for converting the direct-current bus voltage into an electric motor driving voltage; an electric motor, driven by the electric motor driving voltage to operate; and a control module, used for adjusting the direct-current bus voltage outputted by the rectifier module. When the electric motor is operating below a rated rotational speed, the direct-current bus voltage is outputted on the basis of the alternating-current input voltage; and, when the electric motor is operating over the rated rotational speed, the direct-current bus voltage is outputted on the basis of the alternating-current input voltage and of the rotational speed of the electric motor. The control method greatly reduces low-order harmonics of an electrical grid, increases system efficiency, and puts the variable-frequency speed adjusting system in the most efficient work mode.