In the downhill simulation mode (a second operation mode), under the interlock control of the control device 61, the processing unit 61 of the control device 6 generates a second PWM control signal S62 to the motor driving circuit 62 to control the motor driving circuit 62, while disables sending of the first PWM control signal S61 to the PWM control circuit 642. Under such an operation mode, the electrical energy is supplied from the power supply circuit 4, and the motor driving circuit 62 supplies a driving current for the permanent-magnet synchronous motor 3 under control of the second PWM control signal S62, so that the permanent-magnet synchronous motor 3 is operating in a motor mode to generate an acceleration on the external rotor 32. Thus, a virtual reality feeling of simulating a downhill motion is generated.