AC permanent magnet synchronous motor structure
There are many types of permanent magnet synchronous motors, and the waveforms of the induced electromotive force of the stator windings can be divided into a sine wave permanent magnet synchronous motor (PMSM) and a trapezoidal permanent magnet synchronous motor (BLDC). The stator of the sinusoidal permanent magnet synchronous motor is composed of three-phase windings and iron cores. The armature windings are often connected by Y-type, and short-distance distributed windings are used; the air gap field is designed as a sine wave to generate a sine wave back electromotive force; the rotor adopts a permanent magnet Instead of electric excitation, sine wave permanent magnet synchronous motors can be divided into three categories according to the mounting position of permanent magnets on the rotor: convex, embedded and embedded. The motor studied in this paper is a convex-type sine wave permanent magnet synchronous motor. The structure is shown in Figure 1. The stator winding is generally made into multiple phases. The rotor is composed of permanent magnets according to a certain logarithm. For two pairs, the motor speed is n=60f/p, P is the pole logarithm, and f is the current frequency.
At present, three-phase synchronous motors now mainly have two control modes, one is his control (also known as frequency open-loop control); the other is self-control (also known as frequency closed-loop control). The control mode mainly adjusts the rotor speed by independently controlling the external power frequency. It is not necessary to know the position information of the rotor, and the open-loop control scheme of constant voltage frequency ratio is often used. The self-controlled permanent magnet synchronous motor also adjusts the rotation speed of the rotor by changing the frequency of the external power supply. Unlike other control modes, the change of the external power frequency is related to the position information of the rotor. The higher the rotor speed, the higher the stator power supply frequency. The higher the rotor speed is adjusted by varying the frequency of the applied voltage (or current) of the stator windings. Since the self-controlled synchronous motor does not have the problem of out-of-step and oscillation of the synchronous motor of its control, and the permanent magnet of the permanent magnet synchronous motor does not have the brush and the commutator, the volume and quality of the rotor are reduced, and the system is improved. Response speed and speed range, and the performance of DC motor, so the self-controlled AC permanent magnet synchronous motor used in this paper, when the three-phase symmetrical power supply is added to the three-phase symmetrical winding, will naturally produce a synchronous speed rotating stator. The magnetic field, the speed of the synchronous motor rotor is strictly synchronized with the external power supply frequency, and has nothing to do with the load size.
