Control of a bidirectional UPS system using a resonant current control loop

This paper presents an uninterruptible power supply for critical nonlinear loads. The system consists in a voltage source converter (VSC) connected in parallel between the mains and the load The control of the inverter is carried out starting from the resonant current controller (RCC) with an aim of providing various functions. When the main is available, the system permits to compensate harmonics, imbalance and reactive power due to the nonlinear load. When the mains presents a defect (the supply voltage deviates from a given tolerance range), the load is disconnected and supplied by the system from a battery or from a controlled energy production system within 2 ms. The modelling and the simulation of the unit are realised thanks to the software Matlab.