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How to improve the power of permanent magnet synchronous motor
- Feb 02, 2018 -

One, the reason that affects the permanent magnet synchronous motor power factor the permanent magnet synchronous motor used in the pumping unit is a kind of asynchronous synchronous motor, which is operated synchronously after the rotor AC starts and is similar to the AC synchronous motor. Its operation is by the stator coil in the air gap generated by the rotating magnetic field and rotor magnet between the mutual attraction, so that the rotor and stator air gap magnetic field synchronous rotation and work. The rotor is equivalent to resistor circuit, so the power factor is high. Because of no excitation current, its no-load loss is small. Motor efficiency of up to 96%, more than three-phase induction motor high. The factors that affect the power factor of permanent magnet synchronous motor are voltage quality (voltage amplitude) and load rate. When the voltage of the electric network is higher than that of the motor, the permanent magnet motor is operated with inductive load. Therefore, the voltage fluctuation of the power grid will cause the motor power factor fluctuation and compensate the difficulty. If the voltage amplitude and the motor back EMF point Close, the deviation in the ±2% voltage range, the motor power factor is greater than or equal to 0.9, otherwise, the power factor is lower; In addition, when the load rate of PMSM is lower than 25%, the power factor of the motor is also low.

Second, the method of improving the power factor of permanent magnet motor is analyzed by the reason of low power factor of each single well point, the following methods are adopted to adjust respectively.

1. According to the measured load rate appropriate replacement of the motor to ensure the appropriate load rate.

2. Stabilize the system voltage, especially the terminal of heavy load line, the voltage is generally low.

3. The stable single well voltage makes it close to the no-load back EMF of the permanent magnet synchronous motor.

4. When the operating voltage is higher than the back EMF point of Permanent magnet motor, it can be compensated according to the inductive reactive power, so as to improve the factor.

5. When the operating voltage is lower than the back EMF point of the Permanent magnet motor, it can adjust the transformer tap changer, raise the amplitude of two times, and make the motor operating voltage near the counter electric potential point to raise the power factor.

6. For heavy load long line, adjust transformer tap changer, transformer two voltage amplitude is still lower than permanent magnet motor back EMF point, can replace permanent magnet synchronous motor, capacitor cabinet compensation.

Third, adjust the situation and effect analysis through the six teams of oil production of the adjustment test, so that the power factor is not up to Standard Oil wells. At first, the substation and the line capacitance have been adjusted to improve the terminal voltage. Secondly, according to the test results of single well, the corresponding countermeasures are taken, some increase the capacitance, some adjust the transformer retaining position, and adjust the motor power to some wells. The test results show that all the power factor of the permanent magnet synchronous motor is in addition to one, all others are qualified, and the power factor adjusts the electricity tariff greatly.

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