A novel design of line-interactive uninterruptible power supplies without load current sensors

In this paper, a new approach for the design of line interactive uninterruptible power supplies (UPS) without load current sensors is proposed. Based on the interactive structure, this system is constructed that includes the power factor improvement capability in anticipation of increasing the quality of supplying power. With the employment of such an approach, the power converter can be adaptively operated at the active power filter mode or backup mode, by which the power can be supplied to the connected load very reliably. Moreover, as the proposed circuit needs only one current feedback signal where the load current sensors can be saved, the circuit design can be thus simplified significantly. In order to confirm the effectiveness of this proposed design, the approach has been tested through the theoretical analysis and experimental validation under different test scenarios. Test results help support the feasibility and practicality of the method for the application considered.