| Abstract |
An innovative power structure suitable for medium power (>10 kVA) AC/AC conversion is presented. Two poliphase inverters are connected in parallel by their DC-side terminals, their DC voltage supply being switched between near zero and the high voltage of a capacitor bank. Only the DC-side switches are designed for the commutation stresses, while the AC-sides switches can be designed for stressless commutations. Timing requirements are taken into account and practical procedures are considered to minimize the null time interval needed for stresless commutations. A dedicated real-time signal processing is needed to allow the exploitation of the theoretical prerogatives. Peculiar techniques are possible and discussed for the overcurrent protection and the inverters modulation. Simple analog integrators, analog to logic conversion and a high-integration Gate Array logic circuit are adopted. The experimental results of a prototype system, designed for industrial purposes (30 kVA, 380 to 440 V) comply with the expected theoretical performance. |
