Author :
Hua, Bai ; Zhengming, Zhao ; Liqiang, Yuan ; Bing, Li
Abstract :
A filter device is indispensable in most ac adjustable speed drive systems to eliminate the high-frequency components in the output voltage of an inverter, which could protect the insulation of the ac motor and reduce electromagnetic interference. Additionally, due to the restraints of power electronic devices, especially in the high voltage and high power systems with neutral point clamped (NPC) three-level structure, the step-up transformer is usually applied to ascend the output voltage. Thus, the system would be bulky when both of the components, filter and transformer, are adopted simultaneously. This paper efficiently utilizes the leakage inductance of the transformer and effectively integrates the filter and step-up transformer to achieve boosting and filtering simultaneously, and economizes on cost and volume. Besides, some relevant dynamic processes, like dc pre-excitation at the starting process, the self-excitation in the pulse-blocking process, and the response to load variation are discussed, respectively. This integrated configuration is validated by corresponding simulations and experiments, and has also been successfully applied in the three-level NPC 6000V/1MVA system. The other relevant factors in this device are discussed in detail
Keywords :
AC motor drives; AC motor protection; electromagnetic interference; interference suppression; invertors; machine insulation; power filters; power transformers; variable speed drives; 1 MVA; ac motor insulation protection; adjustable speed drive system; electromagnetic interference reduction; integrated LC circuits; inverters; leakage inductance; neutral point clamped three-level structure; power electronic devices; pulse blocking process; step-up transforming filters; AC motors; Electromagnetic interference; Filters; Inductance; Inverters; Power electronics; Power system protection; Power transformer insulation; Variable speed drives; Voltage; Adjustable speed drive system; dc pre-excitation; integrated gate commutated thyristor (IGCT); self-excitation; step-up transformer; three-level;