Due to the shortcomings of the full-pressure full-speed and damper manual adjustment control mode, the original full-pressure speed control system of the fan was modified, and the original full-pressure full-speed operation mode was changed to the energy-saving frequency conversion speed control. When the fan is running, the output voltage amplitude and frequency are controlled by the inverter through the temperature detection signal, thereby automatically switching between the high speed and low speed.
According to the AC asynchronous motor speed formula, when the motor running slip rate does not change much, the motor speed is basically proportional to the frequency of the power supply. By continuously changing the power supply frequency, the operating speed control of the asynchronous motor can be realized. The variable frequency speed control system belongs to the slip power constant type speed control system, and the result of the frequency conversion is to change the rotation speed of the rotating magnetic field.
If the size of the power supply voltage freezing and freezing storage is constant, the frequency will become large, which will directly affect the drop of the magnetic flux, so that the output torque of the motor will decrease; the frequency will become smaller, which will cause the saturation of the magnetic flux, causing problems such as low power factor. In order to keep the magnetic flux value unchanged, the inverter test needs to adopt the variable frequency transformer method. Since the main motor cooling fan load is a constant power load, the relationship between voltage and frequency is a constant. This relationship mode can be set by the setting parameters of the inverter according to the actual situation.
According to the asynchronous motor speed formula, the running speed of the motor is proportional to the power supply frequency of the motor. That is to say, by setting an input frequency through the inverter, the inverter can output an alternating current to supply power to the motor, and the motor will correspond to one. The speed n runs to achieve speed control of the motor. The inverter automatically outputs the corresponding output voltage and output power according to an input frequency. According to the actual situation of production, the corresponding parameters are set by the inverter to achieve the normal operation and energy saving effect of the equipment.