Variable frequency drive
Variable frequency drive is the control of speed by variable speed drive and voltage is the best system for the control of asynchronous motors
Frequency inverters are electronic devices that let you control the speed of an AC motor. If electric AC motors are operated directly from an AC voltage supply system, they can only avail of a fixed speed based on the number of poles and the supply frequency of the power supply system on location.
However, frequency drivers are used when an application requires an adjustable AC voltage (that is, a controllable speed). These variable frequency drives can generate an AC voltage that is variable in amplitude and frequency from a constant AC voltage.
Variable frequency drive how it works?
A frequency inverter (vvvf inverter) is therefore connected upstream of a motor to generate an AC voltage that can be adjusted to meet customer requirements. The power supply system then no longer generates the frequency and voltage level with which the motor operates. Instead, the frequency control takes over this task and controls the output frequency and output voltage.
What is the major advantage of the variable speed drive?
You can use it easily to change the speed of a motor from practically zero to your required nominal speed and have access to a significantly greater speed range. The torque of the motor remains unchanged. Installers can therefore adapt their drive technology to the conditions they require at any time. A frequency inverter control also allows you to directly switch the direction of rotation. A simple vvvf control command is sufficient to change the phase sequence. The downstream AC motor then turns in the opposite direction.
What types of variable frequency inverters are available?
There are two different types of inverter: current-controlled and voltage-controlled. Their functions differ as follows:
- Current-controlled speed drives maintain the ratio of current to frequency at a constant level at all times and are suitable for use in applications in the high megawatt range.
- In the lower megawatt or kilowatt range, in contrast, voltage-controlled speed drives represent the latest technology. They maintain the ratio of voltage to frequency at a constant level at all times. Example: If a motor that is designed for a voltage of 230V and frequency of 50Hz is operated with 25Hz, the voltage is also halved to 115V.
Where are variable speed drives used?
Variable speed drives are used in a huge variety of industrial sectors and applications. Whether in drives for pumps and fans, processing machines, conveyor belts and assembly lines, or cranes and handling systems: Frequency inverters are now indispensable in industrial production. In that sector, an adapted or infinitely variable speed allows for optimized production processes – alongside the additional benefit that speed drives with speed controller ensure energy-efficient operation.
How can our experience be useful to you?
- Kiddie Rides and family Attractions. We customized our variable frequency drives in order to be more competitive and get the maximum power at the same time they save energy.
- Variable frequency inverters technology have been customized to we make ornamental fountain installations, Water Games, Artifical Lakes, etc. All the projects include sustainable development: the fountains are low energy consumption and recycle water in its totality.
- Our own design of inverter drive can be adapted to control a laboratory high-speed centrifuge that offers the opportunity to connect the centrifuge to the line either 110-120V AC or 210-220V AC. The appliance automatically selects the power required to work and it’s ideal for sectors as petrochemical, biology, clinical chemistry and biochemistry.
- Tronic has customized frequency inverters for industrial hospitality ranges of dishwashers, potato peelers, mixers, crushers, vacuum packers, vegetable cutters, cutlery drier, microwave.
- Customized frequency drives specialized in water centrifugal pumps, systems and water-management equipments for the household and residential sector. This sector includes Water intake, Drainage, Water supply and Water circulation.
Variable frequency drive
types and ratings
More information about frequency drive types and ratings you can read here