Digital control of line-interactive UPS

[摘要] ENGLISH ABSTRACT: The digital control of UPS systems has been difficult in the past due to a lack of DSP technology. It was forthis reason not possible to establishing the necessary control to regulate the voltages and currents of the UPSsystems. Recent advances in DSP technology have however provided the means of establishing centralcontrol of the UPS system as well as incorporating more complex closed-loop control algorithms by utilisinga single floating-point DSP.Closed-loop control strategies are investigated and the central control of a line-interactive UPS is establishedin this study. Both the status of the physical system as well as various system parameters are controlled. Thesystem both regulates and charges the storage batteries when the main utility supply is maintained. In theevent that the utility fails, the converter instantaneously changes power flow towards the load with the aim ofmaintaining an uninterrupted voltage supply.Several closed-loop deadbeat based control strategies are investigated for the regulation of the inductorcurrent. A solution for the regulation of the DC-link is also developed and implemented. Furthermore, anintensive study is done on the regulation of the voltage supplied to the load in the event that the utility supplyfails. The investigation is initially approached by considering classical control theory. Although these controlstrategies provided sufficient results, a predictive strategy that is based on the physical conditions of theswitching converter is finally investigated to establish closed loop control of the output voltage. This resultedin a high-bandwidth voltage controller capable of maintaining control under a wide-array of load conditions.

[发布机构] Stellenbosch University