Page 79 - 《橡塑技术与装备》英文版2026年1月

TEST AND ANALYSIS

2.2.1 High efficiency and high power factor accuracy and simple control.
After embedding permanent magnets in the rotor, 2.2.4 Smaller size and lighter weight
permanent magnet synchronous motors rely on the permanent When selecting between permanent magnet synchronous
magnets to establish the rotor magnetic field. During normal motors and conventional variable frequency motors, it can be
operation, the rotor and stator magnetic fields operate observed that for motors of the same power, the frame size of
synchronously, with no induced current in the rotor and permanent magnet synchronous motors is smaller. The analysis
no rotor resistance loss. This alone can improve the motor is as follows:
efficiency by 5% to 10%. Due to the absence of induced （1）The power factor of a permanent magnet
current excitation in the rotor of permanent magnet motors, synchronous motor is not limited by the number of poles. With
the stator windings exhibit almost pure resistive load, resulting the permission of the motor's supporting system, the number
in a motor power factor close to 1. As shown in Figure 4, on of poles of the motor can be designed to be higher, and the
the right is a permanent magnet synchronous motor, where the corresponding motor size can be made smaller.
secondary copper loss is clearly zero. Therefore, the power （2）With the increase in motor efficiency, the
loss is significantly reduced, approximately to 60% of that of corresponding loss decreases, and the temperature rise of the
ordinary motors. motor reduces. Therefore, under the condition of using the
same insulation level, the motor can be designed to be smaller
in size.
（3）The flexibility of the motor structure allows for the
elimination of many ineffective parts within the motor, such
as winding ends and rotor end rings, resulting in a smaller
corresponding volume.
This design, featuring smaller size and lighter weight for
the same power output, is highly suitable for extruder design
Figure 4 Comparison of losses between permanent
magnet synchronous motors and asynchronous motors and installation. Additionally, it offers greater cost-effectiveness
in the selection of reducers, resulting in significant cost
2.2.2 High starting torque and high overload savings.
capacity 2.3 Selection of motor
The starting torque and overload capacity of permanent Currently, there are an increasing number of
magnet synchronous motors are both one power level higher manufacturers capable of producing permanent magnet
than those of ordinary motors. The ratio of the maximum synchronous motors. Through a comparison of different
starting torque to the rated starting torque can reach 3.6 times, manufacturers, this article finds that Honeywell's permanent
whereas for ordinary motors, it is only 1.6 times. This is a very magnet synchronous motors offer high cost-effectiveness. Here,
important characteristic for extruder drives, which require a we briefly illustrate the advantages of Honeywell's permanent
large starting torque. magnet synchronous motors from the following three aspects:
2.2.3 High precision and wide range （1）In terms of rotor design, Honeywell's permanent
The variable frequency control system of permanent magnet synchronous motor utilizes embedded high-
magnet synchronous motors can ensure the motor speed temperature-resistant rare earth permanent magnets. After
accuracy to reach 0.1% to 0.01% without the need for closed- undergoing magnetic stabilization treatment and surface
loop control. In this paper, a high-precision frequency converter chemical treatment, as well as optimized magnetic pole design
is used, which can achieve a speed regulation accuracy of 0.01% and simulation verification, the risk of demagnetization is
under open-loop control, and the adjustment range can reach significantly reduced.
100%. This is very important for extruders, as it offers high （2）Bearing system: Honeywell's permanent magnet

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