Single-phase asynchronous motor without starting capacitor

The invention relates to a single-phase asynchronous motor without a starting capacitor. A bidirectional silicon controlled rectifier circuit of a phase shift delay conduction angle is connected to a secondary winding which increases a wire diameter through a centrifugal switch, or the bidirectional silicon controlled rectifier circuit of the phase shift delay conduction angle is directly connected to a main winding of a motor and the secondary winding is connected to a power supply through a specially-produced electronic-switch normally-closed point. During a starting process, in the motor, a condition that the secondary winding or the main and secondary windings are energized simultaneously is generated alternatively so as to form a rotating magnetic field of a stator; after an expected rotating speed is reached, the electronic-switch normally-closed point gets rid of the secondary winding and a normally-open point carries out short circuit on a bidirectional silicon controlled rectifier main circuit so that the bidirectional silicon controlled rectifier is not impacted by a heavy current when the motor is operated normally.