Regenerative Applications to Stimulate Revenue Growth of Variable Frequency Drive (VFD) Market

Published On : 2018-09-11

Usage of regeneration along with the adjustable frequency drive for returning energy to AC power line, which was once regarded as significantly costly. According to the current scenario, line regeneration connects more common systems as sustainable methods for the purpose of controlled deceleration.

Factors to Increase Usage of Regenerative AFC (adjustable-frequency controller):

  • Controlled or fast decelerating load, such as centrifuges or large rolls.

  • Energy recovery in the heavy-duty-cycle applications as well as applications with constant regeneration, such as unwinder.

  • Generating power along with induction generators propelled by the wind power. Significant advantages for this application are inclusive of:

  • Power generation above the array of wind speeds.

  • Induction generator maintenance, low cost and simplicity.

  • High power factor.

Technology mileposts

Three latest technological developments have created the regenerative AFC (adjustable-frequency controller) into vogue:

  • Improved power semiconductors like IGBTs (insulated gate bipolar transistors) that are hybrid BJT/MOSFET devices. This can switch off and on hundreds of amperes within thousands of time each second, even when it is controlled by the digital signals.

  • Quicker microprocessor control by utilization of 32-bit microprocessors at the high clock speeds. This in turn allows a regenerative regulator for processing complex mathematical algorithms required for finest control of the power factor, power, motor torque, total harmonic distortion, voltage and current.

  • PWM (pulse width modulation) vector AFC (adjustable-frequency controller) usage speed feedback from motor to the control motoring as well as regenerative torque in linear torque-current area for many drives. Various others utilize complex control algorithms for calculating the motor speed and load, thus reducing the necessity for the motor speed feedback. Nevertheless, these usually have lower reaction compared to designs with feedback.

Insights on Regenerative Applications

Regenerative applications are inclusive of machines that lower and lift such as escalators, cranes, hoists and elevators. Other applications are regarded as torque controlled applications such as test stands, web handling systems and tension unwinders. Cyclic applications such as centrifuges are also capable of regenerating significant energy. The regenerative power is being dissipated utilizing a procedure of Braking Resistor and Brake chopper, thereby the drive is likely to be protected from the overvoltage tripping. A noteworthy energy cost-saving is likely to be attained by the regenerative power unit, particularly in frequent off and on applications, deceleration with the large inertia load as well as torque is in the overhauling form.

An induction motor, though not precisely designed for generating power is bound to generate power back in lines, as long as magnetic fields in rotor sustains. While calculating electrical errors on the load centers, one must ponder on this effect for initial stage of error, until the magnetic field collapses on the motors that are attached to it. The VFD (variable frequency drive) is ideal for maintaining the rotor magnetism, thereby decreasing the frequency, as the VFD (variable frequency drive) has been devised for that. There are possibilities that most of the VFDs (variable frequency drives) do not regenerate that energy to AC supply without holding special circuitry for the same.

If one carries lot of VFD (variable frequency drive) together utilizing DC bus connection, energy is likely to flow back spontaneously, thereby feeding other loads. In addition, the DC bus would possibly overvoltage as well as often trip variable frequency drive. The braking resistor is known for burning off the surplus energy too. On a holistic basis, VFD (variable frequency drive) is regarded as a form of motor controller, which propels an electric motor, thereby varying the voltage and frequency supplied to electric motor.