Fast Charge of Dc Link Capacitor in Autonomous System with Vector-Controlled Induction Generator
Keywords
Abstract
The algorithm of fast charging of a capacitor in the DC link for indirect rotor field-oriented vector control system of the induction generator is presented. This algorithm provides the operation of an induction generator with maximum output power over the entire charge time of the capacitor in the DC link. The obtained dependence allows us to determine the reference for torque component of current in the induction generator, which will provide the minimum charge time of the capacitor in the DC link without breaking the physics of induction generator.
There has been performed a comparative study of charge speed of the capacitor in the DC link with implementation of the proposed algorithm and the standard one. In the standard algorithm, the charge of the capacitor in the DC link is carried out by tracking reference voltage trajectory with limited first derivative.
The research was carried out with the method of mathematical modeling using complete dynamic model of induction generator with proportional-integral voltage regulator based on indirect vector control. Comparative tests of charge speed are performed for induction machine with rated power of 5.5 kW and rated speed of 1430 rpm for two speeds: synchronous speed (150 rad/s) and half synchronous speed (75 rad/s).
The results of the research showed that the proposed algorithm provides optimal value of torque component of induction generator current during the entire charge process. By doing this, it provides the operation of an induction generator with maximum power and allows reducing the charge time by more than 30 % comparatively to the standard algorithm that uses voltage reference trajectory with a constant charge rate of the capacitor in the DC link. It should be noted, that the peak maximum values of currents in both algorithms are equal during the whole process of charge. Implementation of the proposed algorithm in control systems of autonomous generator will reduce the start-up time of backup power systems, which is critical for their operation.
