VARIABLE SPEED DRIVE WITH ACTIVE CONVERTER

摘要

A system or method for a VSD with an active converter including a controller, an inductor, an active converter, a DC link, and an inverter. The active converter is controlled to receive an input AC voltage and output a boosted DC voltage to a DC link, up to 850 VDC, the active converter using only low voltage semiconductor switches to provide the 850 VDC DC link voltage. The controller is configured to operate with a reactive input current magnitude equal to zero at a predetermined system load, and at system loads less than the predetermined system load, to introduce a reactive input current that results in a converter voltage having a magnitude less than the input voltage, wherein the vector sum of the input voltage and an inductor voltage is equal to the converter voltage.

主权项

1. A variable speed drive, comprising:
an active converter for receiving an input alternating current power from a power source, the converter configured to convert the input alternating current power to a boosted, regulated DC voltage; a DC link coupled to the converter, the DC link configured to receive and filter the DC voltage and to store energy from the converter; a controller for sensing the DC link voltage and for providing control signals to the converter to control the DC voltage not to exceed a predetermined DC link voltage, the controller adding a non-zero reactive input current value in response to ripple on the DC link voltage, wherein controlling the DC voltage not to exceed a predetermine DC link voltage prevents a voltage rating of solid state devices in the converter from being exceeded; an inductor coupled between the power source and the converter, the input power passing through the inductor, phase currents being sensed by the controller at a converter end of the inductor, and a voltage drop across the inductor being determined by the controller based on the inductance, the phase currents and a frequency of the input power source; and an inverter connected to the DC link, the inverter being configured to convert a DC voltage from the DC link into an output power.