The motor is the core component of the shredder and the power source of the shredder's mechanical transmission system. It is mainly responsible for driving the shredder cutter to rotate the shredding paper forward and reverse the shredded paper. There are two types of motors: DC motors and AC motors. The application of civil shredders is mainly residential homes. If a DC motor is used, the power system of the shredder needs to add a rectifier bridge and VBUS capacitors, resulting in increased manufacturing costs of the shredder and reduced product competitiveness. The system uses the most commonly used single-phase AC asynchronous motor.

Single-phase AC asynchronous motor is mainly composed of stator, rotor, housing and other parts. The main winding and the auxiliary winding in the stator are placed at a 90° difference in mechanical structure layout.When the current flowing through the main winding and the auxiliary winding also differs in phase by 90°, a perfect circle rotation of 3000 r/min will be formed The air gap magnetic field drives the rotor to follow its rotation. Figure 3 is a schematic diagram of the principle of forward and reverse rotation of single-phase AC asynchronous motor. When the single-pole double-throw switch is connected to the lower end, the capacitor C is connected in series with the secondary winding and then in parallel with the main winding; because the voltage between the two ends of the capacitor and the current are 90° out of phase, and the current leads the change in voltage [4], so The current on the auxiliary winding leads the current on the main winding by 90°, forming a rotating magnetic field and driving the motor forward. When the single-pole double-throw switch is connected to the upper end, the capacitor C is connected in series with the main winding and then connected in parallel with the auxiliary winding. At this time, the current on the auxiliary winding lags behind the current on the main winding by 90°, forming a rotating magnetic field to realize the motor reversal. In actual design, the function of the single pole double throw switch is realized by the relay.