Variable frequency speed regulation usually refers to such an electromechanical system: variable frequency speed regulation induction motor, frequency converter, programmable controller and other intelligent devices, terminal actuators and control software, etc., which constitute an open-loop or closed-loop AC speed regulation system. This speed regulation system is replacing traditional mechanical speed regulation and DC speed regulation schemes in an unprecedented manner, greatly improving the degree of mechanical automation and production efficiency, and making equipment increasingly miniaturized and intelligent.
 
Looking at all the motor energy consumption in industrial applications, about 70% of the motors are used for fans and pumps. The benefits of energy saving and emission reduction of such loads are obvious: huge economic benefits and sustainable social effects. Precisely for the above purposes, AC motor variable frequency speed regulation is widely used. For example, when the temperature set by the air conditioner is reduced, it is only necessary to control the motor speed to reduce and reduce the output drive power.
 
In addition to energy saving and easy promotion and application, variable frequency speed regulation asynchronous motors have the advantage of soft starting, and there is no need to evaluate the starting performance. The only key problem that needs to be solved is: the motor's adaptability to non-sinusoidal power supply must be improved.
 
Working principle of frequency converter
The frequency converter we use mainly adopts AC-DC-AC mode (VVVF frequency conversion or vector control frequency conversion). First, the industrial frequency AC power is converted into DC power through a rectifier, and then the DC power is converted into an AC power with controllable frequency and voltage to supply the motor. The circuit of the frequency converter generally consists of four parts: rectification, intermediate DC link, inversion and control. The rectification part is a three-phase bridge uncontrolled rectifier, the inversion part is an IGBT three-phase bridge inverter, and the output is a PWM waveform. The intermediate DC link is for filtering, DC energy storage and buffering reactive power.
 
Variable frequency speed regulation has become the mainstream speed regulation scheme, which can be widely used in stepless speed transmission in various industries. Especially with the increasingly widespread application of frequency converters in the field of industrial control, the use of variable frequency motors has also become increasingly widespread. It can be said that due to the superiority of variable frequency motors over ordinary motors in frequency conversion control, it is not difficult to see variable frequency motors wherever frequency converters are used.
 
The variable frequency motor test generally needs to be powered by a frequency converter. Since the frequency converter output frequency has a wide range of variation and the output PWM wave contains rich harmonics, traditional mutual inductors and power meters can no longer meet the measurement needs of the test. Variable frequency power analyzers and variable frequency power transmitters should be used.
 
The standardized motor test bench is a new test system launched in response to energy conservation and emission reduction and for the motor energy efficiency improvement plan. The standardized motor test bench standardizes and instrumentates complex systems, improves system reliability, simplifies the installation and debugging process, and reduces system costs.
 
Features of variable frequency motors
B-level temperature rise design and F-level insulation manufacturing. The use of polymer insulation materials and vacuum pressure immersion paint manufacturing technology and special insulation structure greatly improves the insulation withstand voltage and mechanical strength of the electrical winding, which is sufficient to cope with the high-speed operation of the motor and resist the high-frequency current impact of the frequency converter and the damage to the insulation caused by voltage.
 
The variable frequency motor has high balance quality, the vibration level is R-level, the mechanical parts have high processing accuracy, and special high-precision bearings are used, which can operate at high speed.
 
The variable frequency motor adopts a forced ventilation cooling system, and all imported axial flow fans are ultra-quiet, long-life, and strong wind. It ensures that the motor can be effectively cooled at any speed, and can achieve long-term operation at high or low speed.
 
Compared with traditional variable frequency motors, it has a wider speed regulation range and higher design quality. Through special magnetic field design, it further suppresses high-order harmonic magnetic fields to meet the design indicators of wide frequency, energy saving and low noise. It has wide range constant torque and power speed regulation characteristics, stable speed regulation, and no torque pulsation.
 
It has good parameter matching with various inverters, and with vector control, it can achieve zero speed full torque, low frequency large torque and high-precision speed control, position control and fast dynamic response control.