A power conversion system converts an input alternating-current voltage having a first frequency into an output alternating-current voltage having a second frequency lower than the first frequency. The power conversion system includes a voltage converter, a PDM controller, and a feedback controller. The voltage converter converts the input alternating-current voltage into the output alternating-current voltage in accordance with control signals and outputs the output alternating-current voltage to a load. The PDM controller performs pulse density modulation of an output voltage command value of the output alternating-current voltage to generate the control signals and outputs the control signals to the voltage converter. The feedback controller generates the output voltage command value based on an output current value of the voltage converter and a state of the load and outputs the output voltage command value to the PDM controller.