| Abstract |
This paper presents a new current regulator for three-phase loads based on orthogonal two-phase d-q as system. Voltage-source inverters having current controllers play an important role in a wide range of industrial systems, such as controlled ac drives, ac power supplies and active filters, where fast current control becomes a prerequisite. Standard solutions based on current regulators can be classified into three categories: hysteresis current controllers, ramp comparators controllers and predictive controllers. The authors present an Hysteresis Current Controller working in an orthogonal d-q system axis. From the error of the current and its derivatives, a new null-vector voltage application strategy has been developed to assure near constant lateral distance between the upper and lower reference limits. With appropriate control strategies, the resulting boundary error can be seen with a circular or square shape. Both regulators, circular and square error boundaries with and without null-vector voltage strategy, are developed here, analysed and digitally implemented using a high speed uP. Computer simulations and laboratory test were made in order to investigate the performance of the proposed regulators, and results showing properties of the different techniques have been discussed. |
