It was not possible at that time to anticipate the significance that this drive concept would ultimately achieve. It was Heinz Ziehlwho, at the start of the fifties, recognized the potential inherent within his father’s idea and he was the one who started to develop the concept further. This saw the first fan with external rotor motor drive start its triumphal procession.

Today the extensive Ziehl-Abegg AG product range provides solutions for the most varied of application sectors: fans for heating, air conditioning and refrigeration, cleanrooms-, agricultural- und railroad engineering. Available here are axial- and centrifugal fans with a diameter range of 120 to 1,250 millimeters that are capable of shifting up to 120,000m³ of air per second. The control technology required here– specifically matched to each application case – is developed and produced by Ziehl-Abegg. Continuous development in the areas of voltage control, frequency inverters and EC technology ensures that Ziehl-Abegg is able to constantly expand its market leadership. The comprehensive product range in the control technology sector encompasses everything from simple voltage regulation to multipurpose controllers.

Outside of the fan sector, motors are mostly deployed in those applications where - for practical purposes – the rotary drive is transmitted through the flange of the external rotor itself. Typical uses are knife-edge systems, grinding belt drives, wheel hub drives for vehicles, agitator drives, motorized driving pulleys and special drives for test benches.

Ziehl-Abegg AC external rotor motors are ideal at combining the advantages of compact and space saving installation with the tried-and-tested drive concept of a wear-free squirrel-cage induction motor. They are available as three-phase alternating current or single-phase alternating-current motors with a variety of pole numbers. A total of 9 output powers, ranging from of 0.1kW to 7kW, and 2 designs, are available for flange or shaft mounting. Practically all the asynchronous external rotor motors from Ziehl-Abegg can be speed controlled through voltage reduction. This makes them almost predestined to be used as a fan drive.

Ziehl-Abegg AG was the world’s first company to develop these motors where the external rotor of the motor incorporates a special copper cage. The rotors are made using a new die-casting method. The significantly higher conductance of the copper compared with conventional materials such as aluminum or silumin enables the rotor losses to be greatly reduced. Depending on the number of poles, this enables efficiency to be boosted by 10-16 percentage points compared with voltage-regulated asynchronous motors with a low-rate speed-torque characteristic, or efficiency to be boosted by 5-9 percentage points in comparison with standard asynchronous motors with a high-rate characteristic. Therefore the new, highly-efficient motors enable major savings to be achieved in terms of power consumption or increased output performances compared with conventional asynchronous motors with identical power. Asynchronous motors with integrated frequency inverter are also available with power outputs up to approximately 3kW.

The history of EC motors at Ziehl-Abegg extends all the way back to 1985, with the series production of EC technology starting up in 1991. Ziehl-Abegg EC drives consist of EC motors and matching EC controllers. The EC motor is a DC external rotor motor comprising a stator and an external rotor fitted with permanent magnets. The EC controller electronically commutates the current in the motor windings – and, with no brushes, it is wear-free. The EC controller also monitors the motor and provides interfaces for simple drive control. The motors have been optimized by means of their compact size and outstanding efficiency across a wide speed-torque range. For a large number of these motors Ziehl-Abegg uses magnetic materials with maximum power density (neodymium-iron-boron). This not only serves to boost efficiency in comparison to other rival products, but also provides a smaller installation space with identical performance. There are 4 motor sizes available with output powers ranging from 0.3kW to 6kW, for either flange or shaft mounting (model dependent) with matching EC controllers. Motors with integrated EC controller, with output powers up to approx. 3kW are also available. EC drives are particularly suited where the vital selection criteria include: greater efficiency in the part-load range and at reduced speeds, the ability to over-speed the fan, low noise, easy initial startup or zero maintenance. Tailor-made solutions are on hand for many applications and various mains voltages.

The advantages of the external rotor motor were also clearly evident in the drives sector particularly with regard to applications requiring space-saving integration capabilities. Nowadays, more and more conventional transmission solutions are being replaced by so-called direct drive/torque motors. The elimination of transmissions, spindles or belts opens up new possibilities for zero-clearance systems. These motors are ideal for applications in which high requirements in terms of dynamics and positioning are placed on the drive. Flat designs with high torque are made possible by external rotor designed torque motors, in which the internal stator forms the stationary part, surrounded by the permanent magnet equipped rotor.

The ZETASYN ZETASYN flat external rotor motor is used as a drive for one of the most important means of transporting people: the elevator. The sheave required for cable traction is flange mounted straight onto the rotor, which enables an extremely compact drive design. Modernization projects using lift-shaft mounted ZETASYN motors offer the possibility of reassigning the space which was previously the machine room, for other purposes. Ziehl-Abegg not only offers motors here, it also provides complete drive solutions. In the elevator sector this includes the drive with safety brake and and relevant control technology. Emergency evacuation in the event of a power failure can be facilitated by an emergency power supply specially matched to the system. The advantages of a reliable drive package for an elevator are obvious.

The permanent magnet synchronous motors have been optimized in terms of the number of poles and the magnetic circuit to provide particularly comfortable and consistent lift operation. These drives enable low speeds to be realized in a precise and uniform manner. A major advantage compared with reduction gearbox drives lies in the improved efficiency, this benefit is even more pronounced in the partial-load range. The reduced power requirements of a synchronous motor also exert a positive influence on power costs.

The integration of a wheel hub into the external rotor motor enabled a more compact vehicle drive to be realized. Here the rotor also forms the hub for mounting the rim. Even the inverter electronics are integrated into the final drive, and water cooling helps to ensure reliable continuous service. The drive is the result of a joint development project with the customer.

Today Ziehl-Abegg drives with external rotor motors are used in the most varied of applications. All around the world customers count on the quality of the motors, they operate reliably, efficiently and comfortably. Alongside elevator and handling systems, Ziehl-Abegg drives are used in printing presses, medical technology, special vehicle drives, knife-edge systems, generator applications or even in platform technology. Their task – to move things!