Patent attributes
In the preferred embodiments, an uninterruptible power supply has multiple UPS modules connected in parallel. Each module has an AC-DC-AC converter and a subcontroller for controlling the operation of the AC-DC-AC converter. A single current sensor senses a total aggregate current flowing from all the modules. Each subcontroller can detect an input voltage, output voltage, and DC bus voltage of each module. Also, each module has unique operating characteristics (e.g., efficiency curve and a responsiveness coefficient K). Operating characteristics data are stored in a memory accessible by the subcontroller. Based on the voltage and current measurements, and the operating characteristics of each module, the subcontrollers perform calculations to determine a DC bus voltage target (unique for each module) that results in each module providing the same output current. Accordingly, only one current sensor is needed, and, consequently, the cost of the UPS device can be reduced.
