Choosing the right drive controller for maximum precision and reliability in high-speed applications

When it comes to high-speed motors, 100,000 revs per minute and more are not uncommon. In turbo blowers and radial compressors, not only do drive controllers ensure top performance, they can also increase energy efficiency, says Mark Checkley

Turbo blowers and radial compressors generate significant energy savings in sewage treatment and power generation plants. They are also in demand in the high-vacuum technology applications and in turbo molecular pumps, where it is essential to ensure extremely precise drive control.

This is necessary, particularly at the high speeds at which the turbo blowers and radial compressors operate, in order to keep the heat generated by the high-speed motor under control at all times. KEB enables this with its COMBIVERT F6 drive controller. Building on applications in the area of process technology, the F6 offers the required performance through high switching frequencies of up to 16kHz and output frequencies of up to 2,000Hz. It is also flexible and adaptable due to a wide range of configurable, sensorless safety options, encoder interfaces and efficient cooling concepts. 

The Z2 sine wave filters from KEB, which are coordinated with the F6 and are specially designed for use at higher frequencies, provide protection against overheating, reduce EMC stress and thereby increase the service life of turbo blowers and radial compressors.

Ventilation systems

Highly efficient turbo blowers are particularly in demand in the area of wastewater treatment. As part of ventilation systems, they continuously supply oxygen to settling tanks, for example, to stimulate the micro-organisms necessary for water purification. Maximum energy efficiency with minimum susceptibility to malfunctions are essential criteria that turbo blowers must meet. Smooth operation – including over long periods of time – requires long-lasting drive systems with precise monitoring functions.

South Korean company Neuros specialises in the production of turbomachinery and uses drives from KEB in their high-performance applications. This calls for drive controllers that are specially designed to work under particularly challenging conditions. The turbo blowers from Neuros must deliver top performance and keep cool even at high speeds. The COMBIVERT F6 drive controllers keep the heat development of the high-speed motor under control and, due to the encoderless control, prove to be practical and economical, particularly under harsh environmental conditions.

High vacuums

LCD screens have become indispensable in modern life. Whether in entertainment electronics, in vehicles, on systems and machines, or in smartphones – flat screens are a key component in many devices. They are just one example of many products that are manufactured partly using high vacuums. To generate the high vacuum conditions, in addition to turbo molecular pumps, compressors are used, which work against the air pressure and create a vacuum. This is a challenging task for the compressor, but it is mastered easily with the aid of the COMBIVERT F6 drive controller.

Refrigerating compressors

Among other things, refrigerating compressors are a central component of air conditioning systems. These cooling machines take over the task of compressing the gaseous refrigerant. This could be, for example, chemical solutions or CO2 gas. For the compressing process, high rotational speeds are required that can be achieved using KEB drive solutions.

Energy generation

Through the use of Organic Rankine Cycle (ORC) heat recovery systems, electrical energy can be generated using organic substances such as waste heat, biomass or geothermal energy. Unlike in other power plants, this does not rely on the use of steam. The vapour that is generated here drives generators so that they can produce electricity. This process within ORC systems requires highly efficient compressors with smooth drives ensured by, for example, the COMBIVERT F6 drive controller.

Four benefits of KEB drive controllers

Cooling concepts: KEB’s drive controllers take over challenging drive tasks so that machines and systems can operate with utmost efficiency. Cutting-edge, technical solutions ensure that they ‘keep a cool head’ at all times. With its air, liquid and oil cooling systems, KEB offers three different cooling technologies which make the drives highly scalable and allow them to be used easily in many different applications. Not just the cooling options, but also the way they are fitted, provide machine and system operators with a high level of flexibility. In addition to control cabinet installation, the cooling systems can also be implemented as push-through versions.

Protective coating: Harsh ambient conditions can attack the electronic components inside machines and systems, causing permanent damage. This is where the optional 3C3 protective coating (IEC/EN 60721-3-3 Class 3C2) comes into play on the printed circuit boards of KEB drive controllers. Adapted to the environmental demands, the coating provides protection and prevents defects and costly downtime. Overall, the service life of inverters is extended – with positive impacts on the operating costs.

Sensorless control (SCL/ASCL): ASCL (Asynchronous Sensorless Closed Loop) and SCL (Sensorless Closed Loop) are proven sensorless control methods developed by KEB. They are advantageous in situations where high output speeds usually make it very difficult or even impossible to attach a sensor. Suitable for asynchronous, synchronous, reluctance, linear, spindle or torque motors, these methods ensure optimal and precise control and sensorless positioning – and are also inexpensive and easy to install. The underlying software contains coordinated virtual motor models.

Sine wave filters: KEB Z2 output filters have been specially designed for use at high frequencies. The use of a special core material, as well as the HF wires of the windings developed especially for KEB, guarantee a configuration with very low losses (η >0.99). This increases the overall efficiency of the drive train. In critical cases, the use of a KEB Z2 sine wave filter makes it possible to operate a medium-frequency motor on a drive controller. An added benefit is that direct operation of the motor on a drive controller can cause the stator and rotor to overheat. Sine wave filters address this precise issue, preventing de-magnetisation and therefore destruction of the motor.

Mark Checkley is Managing Director of KEB UK.