Tag: vfd

In addition to panel control and terminal control, we can also use the RS485 interface (Modbus RTU protocol) for remote control of ATO’s variable frequency drives. RS485 interface is quite useful for the centralized control and monitoring of equipment. This type of control plays an indispensable part in automatic industrial control. That's why we write this blog to illustrate how we can use the Modbus RTU protocol to control the VFD.

Variable Frequency Drive universal frequency converter is a power control device that controls the AC motor by changing the frequency of the working power supply of the motor, and converts the power frequency AC power with constant voltage and frequency into voltage or frequency by applying the principle of frequency conversion technology and microelectronic technology The working process of the variable AC power device is to first convert the power frequency AC power supply into a DC power supply through a rectifier, and then convert the DC power supply into an AC power supply with controllable frequency and voltage to supply the motor.

The analog signals used in the industrial control process are generally standardized, such as 0~10V, 0~20mA, 4~20mA, etc., which can greatly solve the problem of signal compatibility, and also provide equipment for the expansion of use. Convenience. Our VFD also supports analog signal input control. Let me introduce the use of 4-20mA to control the frequency of the VFD.

Variable frequency drive (VFD) is an electric power control equipment that uses frequency conversion technology and micro-electronic technology to control ac motors by changing the frequency of the motor's working power supply. Variable frequency drive by internal IGBT off to adjust the voltage and frequency of the output power supply, according to the actual needs of the motor to provide the required power supply voltage, so as to achieve the purpose of energy saving, speed regulation.

Variable frequency drive (VFD) is a power control device that uses frequency conversion technology and microelectronics technology to control the AC motor by changing the frequency of the motor's working power supply. The VFD adjusts the voltage and frequency of the output power supply by switching on and off the internal IGBT, and provides the required power supply voltage according to the actual needs of the motor, thereby achieving the purpose of energy saving and speed regulation.

In a previous blog, we talked about how to use the external terminals to control the direction, start and stop of the VFD. However we found a problem, that is, the speed regulation of the VFD still needs to use the VFD control panel, so this time we will tell you how to use the external potentiometer to adjust the speed of the ATO variable frequency drive.

The common control methods of VFD are panel control, terminal control, and Modbus RTU control. The panel control is the simplest, only need to connect the power cable and motor cable, and set the parameters to control the speed and direction of the motor. The terminal control and Modbus RTU control methods are more complicated. The following will show you how to How to control VFD with push button switch/terminal control/wire control

Soft starter is a novel motor control device which integrates soft start, soft stop, light load energy saving and multiple protection functions. Its main structure is a three-phase anti parallel thyristor and its electronic control circuit connected in series between the power supply and the control...

With the rapid development of industrial automation, the variable frequency drive, used for frequency conversion debugging, is thereof widely used. As an important role of frequency conversion speed regulation and energy saving, VFD is mainly used to control the AC motor's power control equipment by changing the frequency of the motor's working power supply. It's not only advantageous for improving the enterprise's process and production level, but also plays an important role in energy saving. But how should we choose an appropriate VFD?

What is the frequency converter? Frequency converter outputs the AC power to pure sine wave after the transformation of AC→DC→AC, the output frequency and voltage can be adjusted within a certain range. It is different from the variable frequency drive (VFD) used for motor speed regulation, and also different from the common AC regulated power supply. An ideal AC power supply is characterized by stable frequency, stable voltage, zero internal resistance and pure sinusoidal voltage waveform (without distortion). Frequency converter is quite close to the ideal AC power supply, so more and more countries use it as standard power supply to provide the best power supply environment for electrical appliances, so as to assess the technical performance of electrical appliances.

The main function of DC reactor is to reduce the higher harmonic components of the input current, improve the power factors of the input power source, and limit the short-circuit current. Before the DC reactor is connected with the filter capacitor, it hinders the impulse current amplitude entering the capacitor, and reduces the AC impulse of the busbar. When the power of the frequency converter is higher than 22kW, it is suggested to consider the application of DC reactor. The greater the power of the converter is, there should be a higher possibility of using the reactor. Because when there is no DC reactor, the capacitor filtering of the frequency converter will result in the serious distortion of the current wave, thus further causing the serious distortion of the network voltage waveform. In addition, it is very harmful to the service life of the rectifier bridge and filter capacitor of the frequency converter.

As everyone knows, direct starting of water pump would cause the water hammer effect. Namely when the water pump starts and stops, water impacts the pipe and cause a serious water hammer. When the power is off suddenly or the valve turns off quickly, a water impact wave generates due to inertia of pressure flow, which is like the knock of a hammer, so it’s called water hammer. Sometimes the force generated from water impact wave may be great and damage valve or pump, therefore, to avoid the negative effect of water hammer effect, the pump’s rotation speed should increase to the rated speed slowly when it’s started. Two methods are applicable, one is the variable frequency starting, another is the soft starting.

ATO sells VFD's power range from 1/2hp to 300hp, include single phase input and output VFDs from 1/2hp to 7.5hp, 110v/120v input VFDs from 1hp to 7.5hp, single phase input to three phase output VFDs from 1/2hp to 10hp, three phase input/output VFDs from 1hp to 300hp. All VFDs are manufacturer direct sale and quality guaranteed. Widely used in fans, pumps, lathes, cable machinery, printing and dyeing equipment, chemical machinery, plastic machinery, etc. The following are ATO variable frequency drive price lists for your reference. If you want more information, please go to ATO VFD products page.

A device that converts alternating current with constant voltage and frequency into alternating current with variable voltage or frequency is called "variable frequency drive". VFD has the functions of voltage regulation, frequency modulation, voltage stabilization, speed regulation etc. VFD is generally used to control 3 phase AC motor in variable speeds. Now the three phase 220v-240v motor can run on single phase 120v power supply. ATO offers you 110v/120v input, 220v/230v/240v output VFDs. It can not only realize single phase input & output, but also convert single phase to three phase.

1 Electromagnetic Design

For a common asynchronous motor, major performance parameters considered in design include the overload capacity, start performance ,efficiency and power. As for a VFD, its breakdown slip is inversely proportional to the power frequency, and it can start directly when the breakdown slip is near 1, therefore, the overload capacity and start performance doesn’t need to consider, the key problem to be solved is how to improve the adaptability of the motor to non sinusoidal power supplies. Methods are as follows:

The functions of input line reactor
It can restrain harmonic current, improve power coefficient, weaken surge voltage in input circuit, the impact of current on VFD, the influences of power voltage, limit current surge caused by grid voltage change and switching surge, spike pulse or voltage defects in phase change of rectifying circuit, effectively protect VFD and improve power coefficient. Input line reactor not only can stop the disturbance from power grid but reduce the pollution of power grid by harmonic current produced by rectifying unit.

Variable Frequency Drive (VFD), aka variable speed drive (VSD), generally it's using for controlling 3-phase AC motor in variable speeds. It's important to know, control 1-phase motor speed by a VFD may cause overheat of the motor, as well as the service life. It's recommended to upgrade the motor to three phase AC motor, which you can also connect the 3-phase motor to single phase power supply by using a single phase to three phase VFD, then control the speeds. Anyway, in technical it's possible to use a VFD for single phase motor speed controls, here ATO will show you details about running a single phase motor on a VFD.

It is found that the speed of air compressor motor is proportional to the actual consumed power of the air compressor. Therefore, it is necessary to reduce the motor speed in order to reduce the actual consumption of the air compressor. The use of VFD in air compressor system can realize the real time control of motor speed (output power) without changing the air compressor motor torque through the accurate coordination of electrical control and frequency control in the air compressor system. To change the compressor speed to respond to the system pressure changes and to maintain stable system pressure can realize the output of high quality air pressure according to demand.

How to control the speed of three phase induction motor? The speed control method includes: changing the number of poles, stator voltage control, stator frequency conversion, cascade speed control, double-feed speed regulation, hydraulic coupler, electromagnetic slip clutch, etc.
The actual speed of three phase asynchronous motor is given by n=n_s (1 - s) =120f /p (1-s). It can be seen from the formula that the speed of 3 phase induction motor can be changed by the means of changing the number of induction motor’s poles "p", the slip "s" and the frequency of power supply"f".

The traditional industrial agitator usually conducts no regulation or regulates the speed in mechanical method. The speed regulation in mechanical method will increase the loss of the industrial agitator. Meanwhile, the industrial agitator will work in fluctuating status. Furthermore, it will also work in the status of "big rated power with small load power", which is quite not economic. The motor power of the industrial agitator in operating under the frequency conversion speed control is similar to its characteristics of the revolving speed and pump load. Using VFD for speed regulation will obtain a substantial power saving rate.