High-performance Control of UPS Inverters Using a B-Spline Network

The purpose of a voltage controller for UPS inverters is to produce stable and regulated output voltage with low distortion under all loading conditions, especially under nonlinear loads. In this paper, a B-spline network controller that is easy to implement is proposed for UPS inverters. A modified weights-updating law with ´forgetting factor´ is introduced to increase the robustness of the scheme against measurement noise, initialization error and/or variation of system dynamics due to parameter drifts. Detailed design formulas for two parameters of B-spline network: the B-spline support width and the learning gain are given based on stability analysis in frequency domain. A parallel PD controller is also adopted as feedback control in order to improve the dynamic performance. Experimental results show that the proposed controller can achieve very low total harmonic distortion and fast error convergence under different loads even with only one sensor. Moreover, the proposed controller also can obtain fast dynamic response