A VOLTAGE CONTROL STRATEGY FOR CURRENT-REGULATED PWM INVERTERS

Alternative voltage control strategies for current-regulated PWM inver ters are analyzed, including previously established feedforward and fe edforward/feedback controllers and a newly proposed decoupling feedbac k central strategy. The steady-state and dynamic characteristics of ea ch of these control methods are illustrated and compared for a selecte d inverter design, It is shown that the feedforward controller exhibit s steady-state error and an undesirable overshoot of the output voltag es during startup, The addition of a feedback loop eliminates the stea dy-state error and reduces the overshoot; however, the natural respons e is underdamped regardless of the choice of feedback gains, A decoupl ing feedback control strategy that eliminates the disadvantages of the feedforward and feedforward/feedback controllers is described, Using the decoupling feedback controller, it is possible to eliminate the st eady-state error and place the closed-loop poles wherever desired, Mor eover, if the closed-loop poles are selected appropriately, it Is poss ible to eliminate the overshoot of the output voltages during startup transients.