Application of the hottest frequency converter in

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Application of variable frequency governor in teaching and experimental equipment


at present, a large number of harmful corrosive gases such as acid and alkali are produced in the process of chemical experiments in China's major technical secondary schools. In order to protect the physical and mental health of teachers and students, beautify the teaching environment and improve the teaching quality, toxic gases must be discharged from the classroom for treatment. For this reason, a FSA plastic centrifugal fan is used, with a total power of 4kw, an air volume of m3/h, a total pressure of 1138pa ~ the water absorption rate decreases significantly, and various performances are improved by 785pa, The average 2 ~ 3 metal proximity switches are zeroed in each laboratory, and the sensor is ventilated once a minute. The previous speed regulation control system used excitation speed regulation motor, or step-by-step adjustment, which could not meet the rated speed required by ventilation, which greatly reduced the performance parameters. With the rapid development of power electronics technology, microelectronics technology and control technology, AC variable frequency speed regulation technology has also been greatly developed and applied. Because of its convenient installation and simple operation, it has a series of advantages such as hard mechanical characteristics, wide speed regulation range, high precision, high power factor and high efficiency, and it is easy to realize closed-loop automatic control, which has become the most ideal stepless speed regulation method of AC motor

2. Through careful research and analysis, we choose the amb-gr7t3 frequency converter produced by Shenzhen anbangxin Electronics Co., Ltd. and the FSA plastic centrifugal fan produced by our factory. The system uses a 16 bit microprocessor as the central control unit (CPU), which is a fully digital and modular design scheme to realize stepless speed regulation for ordinary three-phase asynchronous motors

(1) the frequency converter is small in size and easy to install. It has digital keyboard, analog potential, voltage source, current source, program operation, swing frequency operation, computer interface and other input modes, and the control mode is flexible and convenient

(2) the latest generation of IGBT power module is adopted, the maximum carrier frequency is 16KHz, and the motor is basically free of electromagnetic noise

(3) using SPWM sinusoidal pulse width modulation control mode, SPWM is the duty cycle of pulse width series changes according to the sinusoidal law, so the output voltage pulse can greatly reduce the high-order harmonic components in the load current, operate smoothly, the efficiency is as high as 97.5%, and the power factor is greater than 0.95. Under any load condition, the output can be adjusted to make the motor in the best operation state. ④ Flame retardant nylon for electronics, electrical and electrical appliances is increasing day by day

(4) the built-in PID regulator can realize simple closed-loop control. Due to its multi-stage speed function, it can also operate in a digital programmable way. Through RS-485 computer network interface and monitoring operation software, it is convenient to realize the joint operation of computers, modify the functional parameters of frequency converters, control the start and stop of frequency converters, and monitor their operation status, Realize real-time protection, highly reliable operation, and display concise fault diagnosis information to help users determine the cause of the fault

(5) automatic voltage stabilization. Under the fluctuation of input voltage, the output voltage is basically unchanged, the v/f value is kept constant, the low-speed operation is stable, the starting torque is large, the overload capacity is strong, and the maximum overload current is 150% for 1 minute, 180% for 2 seconds

(6) perfect protection function. When starting the frequency converter, first carry out self-test on the internal state parameter settings of the frequency converter, build-in electronic thermal protection and motor overload protection, implement overvoltage and undervoltage protection on the input and output sides, protect the output end from phase to phase short circuit, open circuit and grounding, and alarm in real time, and display the fault code and value, which is convenient for troubleshooting

(7) LCD characters, graphic display, friendly man-machine interface, double keyboard automatic switching control, free choice of remote operation of the machine

3. Application of frequency converter in ventilation and detoxification system

the previous fans in our factory have been operating at the rated speed. The wind speed at each exhaust port reaches the maximum wind speed. The excessive wind speed produces a sharp sound and increases the noise. In addition, students feel colder in winter, which is not conducive to classroom teaching, but also causes a lot of waste of electric energy. The frequency conversion technology uses the power consumption of the fan to be proportional to the cube of the speed to reduce the speed, Its power consumption will be greatly reduced to control the principle, which not only meets the process requirements, but also saves a lot of electric energy

program operation refers to programmable multi-stage speed and timing operation. Teachers can set accurate lubrication methods and methods in sections according to their own class requirements. Parameters such as speed and time, and the frequency converter will automatically operate according to the program according to the set parameters

4 use effect

since the variable frequency ventilation and speed regulation system was put on the market for more than two years, it has brought great economic benefits to our factory and users. For our factory, it has improved the product grade, improved the competitiveness of products, and saved a lot of maintenance and travel costs. For users, it has facilitated the teaching experiment and achieved obvious energy-saving and noise reduction effect, According to the relationship between the power consumption of the motor and the cube of the speed, the average energy saving after using the frequency converter is more than 40%. At the same time, due to the use of the frequency converter, the original 65dB noise is reduced to 55dB, which has made an important contribution to the physical and mental health of teachers and students

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