High quality online uninterruptible power supplies (UPS) are widely used in applications e.g. precision medical equipment with critical loads. This paper proposes a low-cost and high performance online UPS system. Firstly, the performance improvement of a bidirectional switch based bridgeless power factor (PFC) converter, which is regulated by a hybrid control strategy with load current feedforward is studied. Secondly, the proposed closed-loop controller integrates improved predictive current control with predictive voltage control and applies to the second-stage neutral-point-clamped (NPC) three-level inverter for low output voltage harmonics. Moreover, a push-pull dc-dc converter interfaces and boosts voltage of a 24V battery bank as the backup energy source. Considering complexity of the UPS system as well as cost reduction, we implement a multi-task decomposition method for control on a monolithic low-cost digital signal processor (DSP) embedded with Control Law Accelerator (CLA). Finally, the experimental results from a 1kVA a prototype can effectively verify validly of the theoretical analysis and design.
- Online UPS
- Bidirectional switch bridgeless PFC
- Multi-task decomposition
- Three-level inverter
- Digital control
- Low costs
Lin, Q., Cai, F., Wang, W., Chen, S., Zhang, Z., & You, S. (2020). A High Performance Online Uninterruptible Power Supply UPS System Based on Multitask Decomposition. I E E E Transactions on Industry Applications, 55(6), 7575 - 7585. https://doi.org/10.1109/TIA.2019.2935929