The controller can realize the direct short-circuit protection of the output terminal, even when the motor is at the highest speed action (the highest voltage is usually output at this time) directly short-circuit the output terminal of the controller, the controller can also be very reliable protection. During protection, the circuit automatically reduces the output current to protect the safety of the battery. At this time, the current is about 0.3A, and the status of the output terminal can be checked at any time. When the output terminal is faulty, the controller can automatically resume normal control with self-recovery function Therefore, the controller has self-protection capability, which improves the safety of the controller and the storage battery, and also improves the tolerance to the fault of the motor itself. In view of the actual use of electric bicycles, locked-rotor is one of the possible working conditions. If the controller can reliably protect the output terminal from short-circuit, the controller can also protect and protect the motor when the motor is locked. And battery safety. If there is only a controller with current limiting function, it will output a large current (such as current limiting 14A) at this time. These make the battery (capacity 12AH) in a large current discharge state (14A), which will affect the service life of the battery. In addition, a large current flows through the motor windings. Over time, the temperature rise of the motor will rise, resulting in aging of the winding insulation, which may affect the life of the motor, or burn the motor.