Motor manufacturers are working on various concepts to achieve high levels of efficiency in electric motors. In addition to the tried-and-tested three-phase asynchronous motors (DASM), permanent magnet motors (PM) and synchronous reluctance motors (SynRM) now also boast the highest energy efficiency classes in industrial and commercial applications. All motor technologies in the same efficiency class offer comparable efficiency at the nominal point, but also have many differences, for example in terms of start-up behavior or in partial load operation. For the user, the multitude of motor technologies means one thing above all: he must find the “right” technology for his application in order to achieve maximum energy efficiency and thus savings.

In principle, almost all motors can be controlled with fixed voltage values at defined frequencies, the so-called V/f characteristic curve. However, only control algorithms specially adapted to the respective engine technology guarantee the efficiency advantages of the individual technologies. Only with these algorithms can the motor be operated optimally at every operating point, even with changing loads.

Almost all current motor technologies can be operated by a frequency inverter or even require one. However, this also poses a problem: can all solutions be operated with just one device?

Ideally, a frequency inverter should be able to control all motor types, not only via the simple v/f characteristic curve, but also with optimized algorithms for highly efficient applications. If this is not the case, the user runs the risk of having to use a very heterogeneous system landscape. In practice, this means more training for designers, operators and maintenance personnel, as well as higher costs for stocking the various systems. It is therefore advantageous for the user to be able to control all motor types with just one frequency inverter. For example, as an independent manufacturer of frequency inverters, Danfoss supplies a solution that can control all standard motors commonly used in industry and building automation. Throughout the entire power range, plant operators can thus rely on uniform operation, the same interfaces, the same extensions, and proven, reliable technology. Spare parts inventory in their plants is simplified, as is maintenance, and training costs are reduced.

Danfoss frequency inverters offer optimized control algorithms as standard for high efficiency even for standard asynchronous and permanent magnet (PM) motors. Synchronous reluctance motors are now also being added. Danfoss also simplifies commissioning, as the inverters offer not only simple operation but also other helpful functions such as automatic motor adjustment. The frequency inverter measures the connected motor at standstill. This method has been around for several years. Over time, however, it was expanded to include strategies for PM and synchronous reluctance motors. With this procedure, it is possible to measure the motor at standstill within 3 seconds after entering some nameplate data.