Sliding Mode Control of Energy Recovery Transformer-Less Power Accumulator Battery Pack Testing System

The main objective of the present work is to apply sliding mode controller to medium voltage and high power output energy recovery power accumulator battery pack testing systems (ERPABPTS), which is composed of a three-level neutral point clamped three-phase voltage source inverter (NPC-VSI) and a non-isolating DC-DC converter. A decoupled scheme for the proposed system is put forward, based on that, two sliding mode plane for active and reactive current component control are illustrated. The ERPBPTS is used to integrate discharging energy to the power grid with high efficiency when performing current test, active and reactive power references for the grid-connected inverter are determined based on the discharging energy from the DC-DC converter. Without using the isolation transformer, the proposed scheme could greatly reduce the total volume of the system, offer less total harmonic distortion, and meanwhile maintain higher DC-link voltage utilization. The proposed method is implemented and verified both by simulation and experimental results on a laboratory hardware platform using 175kW IGBT-based ERPABTS using an embedded DSP controller