★Permanent magnet synchronous motor★

▶Permanent magnet synchronous motor uses permanent magnet to provide excitation, which makes the structure of the motor simple, reduces the processing and assembly costs, saves the collector ring and brush which are easy to cause problems, and improves the reliability of the motor operation; Because there is no excitation current and no excitation loss, the efficiency and power density of the motor are improved.

Compared with ordinary three-phase asynchronous motor, it has the following advantages:

• High efficiency: after the permanent magnet material is embedded in the rotor, the rotor and stator magnetic field operate synchronously during normal operation, and there is no induced current in the rotor winding, no rotor resistance and hysteresis loss, which improves the efficiency of the motor

• High power factor: there is no induced current excitation in the rotor of permanent magnet synchronous motor, the stator winding presents resistive load, and the power factor of the motor is close to 1, which reduces the stator current and improves the efficiency of the motor

• Low temperature rise: there is no resistance loss in the rotor winding and almost no reactive current in the stator winding

• Small volume, light weight and less consumables: the volume, weight and materials of permanent magnet synchronous motor with the same capacity can be reduced by about 30%

• Small armature reaction, strong overload resistance and large starting torque

I n terms of control, due to the additional cost (encoder and encoder card) of PMSM with PG vector control and the increase of fault points, PG free vector control (open-loop vector) has been widely applied in recent years.

However, there are more or less the following problems in the application of open-loop vector control of synchronous motor in the market

When starting, the motor is easy to reverse

The search time of magnetic pole position is too long when starting;

The control of low frequency motor is not stable and the load capacity is poor;

High frequency current oscillation, easy out of step;

It is difficult to start with load and speed or the impulse current is large when starting.

How to solve it?

★Hpmont's open-loop vector control technology★

Technical features:

1. The position of magnetic pole must be searched accurately when the PMSM starts, otherwise the starting torque is small and it may cause galloping. Hipmont hd50-olv self-developed synchronous motor start pole position fast search algorithm, fast search speed, high precision, and no motor reverse phenomenon

2. Wide speed range, from 0.30hz to 650.00hz full speed range can achieve stable control within the fundamental frequency

3. Low speed motor control stable, start torque, minimum 0.5Hz full load start

4. Stable high frequency current control in full power range

Figure 1: full load 500Hz current waveform of 110KW permanent magnet synchronous motor

5. The self-developed advanced speed tracking algorithm can realize the steady start of PMSM with load and speed in full power section, with fast tracking speed (tracking time can realize 0 second tracking start without any additional conditions) and small impact current (the impact current at the tracking moment is within the rated current of motor)

Figure 2: continuous start stop speed tracking waveform with full load

(continuous start time interval can be infinitely small)

Figure 3: 180 Hz speed tracking startup waveform with full load

At present, the open-loop vector control technology of hipmont permanent magnet synchronous motor (PMSM) has been widely used in air compressor, industrial fan and other industries with its excellent control performance.