Power supply and control method thereof

A power supply includes multiple power modules and a control circuit. Input terminals of the power modules are connected in star connection such that each power module receives a phase input voltage. Output terminals of the power modules are connected in parallel. Each power modules includes a first and a second converter. The first converter converts the phase input voltage into an intermediate bus voltage. The second converter outputs a DC supply voltage according to the intermediate bus voltage. The control circuit is coupled to the power modules and configured to output first and second driving signals to control the first and second converters in the power modules. A bus voltage average value is calculated by the control circuit according to the intermediate bus voltages of the power modules, and the first and the second driving signals for the power modules are generated according to the bus voltage average value.