A Adjustable Frequency Drive (VFD) is a type of motor controller that drives an electric motor by varying the frequency and voltage supplied to the electric motor. Other names for a VFD are adjustable speed drive, adjustable 
speed drive, adjustable frequency drive, AC drive, microdrive, and inverter.
Frequency (or hertz) is directly linked to the motor’s speed (RPMs). Basically, the faster the frequency, the faster the RPMs go. If an application does not require a power motor to run at full swiftness, the VFD can be used to ramp down the frequency and voltage to meet the requirements of the electrical motor’s load. As the application’s motor rate requirements change, the VFD can simply arrive or down the motor speed to meet the speed requirement.
The first stage of a Variable Frequency AC Drive, or VFD, may be the Converter. The Udl Speed Variator converter is usually made up of six diodes, which act like check valves used in plumbing systems. They enable current to flow in mere one direction; the direction demonstrated by the arrow in the diode symbol. For example, whenever A-phase voltage (voltage is similar to pressure in plumbing systems) is definitely more positive than B or C phase voltages, after that that diode will open and invite current to stream. When B-stage becomes more positive than A-phase, then the B-phase diode will open and the A-stage diode will close. The same holds true for the 3 diodes on the negative side of the bus. Thus, we obtain six current “pulses” as each diode opens and closes. That is called a “six-pulse VFD”, which may be the standard configuration for current Adjustable Frequency Drives.
Why don’t we assume that the drive is operating on a 480V power program. The 480V rating is definitely “rms” or root-mean-squared. The peaks on a 480V program are 679V. As you can plainly see, the VFD dc bus has a dc voltage with an AC ripple. The voltage runs between approximately 580V and 680V.
We can get rid of the AC ripple on the DC bus with the addition of a capacitor. A capacitor operates in a similar fashion to a reservoir or accumulator in a plumbing system. This capacitor absorbs the ac ripple and provides a soft dc voltage. The AC ripple on the DC bus is typically significantly less than 3 Volts. Thus, the voltage on the DC bus becomes “around” 650VDC. The actual voltage will depend on the voltage degree of the AC collection feeding the drive, the level of voltage unbalance on the energy system, the electric motor load, the impedance of the power program, and any reactors or harmonic filters on the drive.
The diode bridge converter that converts AC-to-DC, is sometimes just referred to as a converter. The converter that converts the dc back again to ac is also a converter, but to distinguish it from the diode converter, it is generally referred to as an “inverter”. It is becoming common in the industry to refer to any DC-to-AC converter as an inverter.
Whenever we close one of the top switches in the inverter, that stage of the engine is linked to the positive dc bus and the voltage upon that phase becomes positive. Whenever we close one of the bottom level switches in the converter, that phase is linked to the negative dc bus and becomes negative. Thus, we are able to make any phase on the electric motor become positive or negative at will and may therefore generate any frequency that people want. So, we can make any phase maintain positivity, negative, or zero.
If you have an application that does not need to be run at full speed, then you can decrease energy costs by controlling the electric motor with a adjustable frequency drive, which is among the advantages of Variable Frequency Drives. VFDs enable you to match the acceleration of the motor-
The aluminium casing benefits weight reduction for more convenient applications and transportation.
The simple design allows both foot or flange installation to standard unit, reducing stocking amounts and allowing quick delivery.
The closed insight flange can be an integral part of the variator casing for easy installation and prevents probability of oil leaks.
The magnetic breather plug maintains a clean lubricant and extends maintenance intervals.
The oil bath operation provides high efficiency for noiseless and vibration free running.
The unit can operate in both directions, input and output shafts rotate in the same direction.
14.6 UDL performance table for UDL Series Swiftness Variator (N1=1400R/MIN)
UDL series planet cone-disk stepless mechanical variator can be a new generation of products produced by ourselves based on advanced technology. BV series stepless mechanical variator are widely used for conveying, ceramics, packing, chemical, textile, foodstuffs, medication, printing, rubber, Machine-equipment, and all sorts of automatic production lines, pipelines and assembly lines which need speed-reuglation, etc. Its primary features are follows:
