Frequency conversion speed control, usually refers to such an electromechanical system:
frequency conversion induction motor, frequency converter, programmable controller and other intelligent devices, terminal actuators and control software, etc., constitutes an open-loop or closed-loop AC speed control system.
This speed control system is replacing the traditional mechanical speed control and DC speed control scheme with unprecedented momentum, making the degree of automation and production efficiency of machinery greatly improved, so that equipment increasingly tends to miniaturization, intelligent.
Looking at the industrial application of all motor energy consumption, about 70% of the motor is used in fans and pumps load, the load of energy saving and emission reduction.
The benefits are obvious: huge economic benefits and sustainable development of social effects. Precisely based on the above purposes, AC motor frequency control is extremely widely used.
For example, for inverter air conditioners, when the temperature set by the air conditioner is lowered, it is only necessary to control the speed of the motor to reduce the output driving power.
In addition to energy saving, easy to promote the application, frequency conversion asynchronous motor has the advantage of soft start, no need to test the starting performance.
The only key problem that needs to be solved is: the motor must be strengthened to improve the adaptability of non-sinusoidal power supply.
Frequency converter working principle
The inverter we use mainly adopts the AC-direct-AC method (VVVF inverter or vector-controlled inverter), which first converts the frequency AC power into DC power through a rectifier, and then converts the DC power into AC power with controllable frequency and voltage to supply the motor.
The circuit of the inverter is generally composed of four parts: rectifier, intermediate DC link, inverter and control.
The rectifier is a three-phase bridge type uncontrolled rectifier, the inverter is an IGBT three-phase bridge type inverter with PWM waveform output, and the intermediate DC link is for filtering, DC energy storage and buffering reactive power.
Inverter speed control has become the mainstream speed control program, can be widely used in all walks of life stepless variable speed transmission.
Especially with the increasingly widespread application of inverters in the field of industrial control, the use of inverter motor is also increasingly widespread, so to speak, due to the superiority of inverter motor in frequency control than ordinary motor, where the inverter is used we are not difficult to see the figure of inverter motor.
Inverter motor test generally need to use inverter power supply, because the inverter output frequency has a wide range of variation, and the output PWM wave contains rich harmonics.
The traditional transformer and power meter can not meet the measurement needs of the test, should use inverter power analyzer and inverter power transmitter, etc..
The standardized motor test bench is a new test system launched in response to energy saving and emission reduction and for the motor energy efficiency improvement plan.
The standardized motor test bench standardizes and instrumentalizes complex systems, improves system reliability, simplifies the installation and commissioning process, and reduces system costs.
Features of frequency conversion special motors
B-class temperature rise design, F-class insulation manufacturing.
The use of polymer insulation materials and vacuum pressure dipping paint manufacturing process and the use of special insulation structure.
So that the electrical windings using insulation voltage and mechanical strength has been greatly improved, enough to withstand the high-speed operation of the motor and resistance to high-frequency current impact of the inverter and voltage damage to the insulation.
Frequency conversion motor balance quality is high, vibration grade R mechanical parts processing precision, and the use of special high-precision bearings, can be high-speed operation. Inverter motor with forced ventilation cooling system, all imported axial fan ultra-quiet, high life, strong wind.
To protect the motor in any speed, get effective heat dissipation, can achieve high-speed or low-speed long-term operation.
Compared with the traditional inverter motor, with a wider range of speed regulation and higher design quality, by the special magnetic field design, to further suppress the high harmonic magnetic field to meet the design index of wide frequency, energy saving and low noise.
With a wide range of constant torque and power speed regulation characteristics, smooth speed regulation, no torque pulsation.
It has good parameter matching with all kinds of inverters, and with vector control, it can realize zero speed full torque, low frequency high torque and high precision speed control, position control and fast dynamic response control.
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