An energy conversion device is provided, including a motor coil (11), a bridge arm converter (12), and a bidirectional bridge arm (13). The bridge arm converter (12) is connected to the motor coil (11) and the bidirectional bridge arm (13). The motor coil (11), the bridge arm converter (12), and the bidirectional bridge arm (13) are all connected to an external charging port (10). Both the bridge arm converter (12) and the bidirectional bridge arm (13) are connected to an external battery 200. The motor coil (11), the bridge arm converter (12), and the external charging port (10) form a DC charging circuit for charging the external battery 200. The motor coil (11), the bridge arm converter (12), the bidirectional bridge arm (13), and the external charging port (10) form an AC charging circuit for charging the external battery (200). The motor coil (11), the bridge arm converter (12), and the external battery (200) form a motor drive circuit.