Single-phase motor winding tap H-type connection three-speed circuit

The circuit is shown in the figure. After the speed regulating winding LD and the auxiliary winding LA are connected in series, they are then connected in parallel between the tap of the main winding LR and the power supply. LD and LA are in the same slot and electrically in the same phase. The principle of speed regulation is: the circuit causes three asymmetric phases with inconsistent phases to be formed between the upper half, lower half of LR and some windings of auxiliary winding LA. When the tap position of the LD is changed, the three asymmetric phases between the three windings are changed, that is to say, the rotating magnetic field intensity of the motor is relatively changed, thereby realizing the speed regulation of the motor.