Explain the different types of inverter drive expanded
Explain the different types of inverter drive expanded
There are several different types of inverter drive, each having its own benifits and tailoring to specific application sectors, environment and control method. Standard open loop inverter drives are generally designed for use with standard, asynchronous induction motors. They are designed for general industrial use. HVAC inverter drives are designed for use with fan and pump type loads, they have a lower overload rating and specific fan/ pump features.
Standard open loop inverter drives are designed to control the speed and torque of three phase AC induction motors by adjusting the frequency, torque and voltage of the supply to the connected motor. They are used across a wide range of industries, fans, pumps, compressors, conveyors, agriculture, cranes and hoists and much more.
Open loop vector inverters offer a more accurate motor control algorithm allowing more precise motor voltage and current control thus giving better speed and torque control of the motor. These inverters have a better understanding of the position of the motor's rotor, which allows better motor voltage control at low motor speeds, thus giving better low speed torque performance. Open loop vector inverters are generally used in applications requiring good low speed torque performance such as cranes and hoists, augers, food and drink industry and special effects type applications. A forced ventillation fan may be required on the motor's non drive end, to provide additional cooling, for low speed operation.
Closed loop vector inverters require the addition of a feedback device (normally an incremental encoder) on the motors non drive end, this allows the inverter to gain very accurate information regadaring critical motor parameters. This then allows excellant all round motor performance. These inverters tend to be used in CNC macines, precision lathes, winders and unwinders.
Servo drives/inverters also require the addition of a feedback device (normally a resolver) on the motors non drive end, these drives can provide very precise control over the torque, rotor position, rotor velocity, and acceleration of specialist servo motors. They are used in applications requiring precise position and torque control, such as CNC machines, robotic packaging and machinery centres.
Regenerative inverters or regen drives push energy from decelerating motors back into the power grid. They are useful in applications where motor braking or motor deceleration happens often, application types include passenger and equipment lifts, cranes, hoists, winders and unwinders The drives greatly improve energy efficiency through reduction in heat generation. They are however more expensive than their non regenerative equivalents.
Inverter manufacturers offer different IP ratings (ingress protection) for thier various models. IP20 for cabinet mount inverters, IP21 for plant room, IP55 for dusty damp environments, IP66 for wet and very dusty environments and IP66-outdoor for outdoor use.
