Patented technology for controlling motors

In NFO Sinus the voltage in the transistors is switched so that the inverter emits a sinusoidal voltage output. This means that you avoid all electromagnetic interference.

Conventional frequency inverters, based on PWM technology, cut up the voltage into short pulses, which leads to electromagnetic interference (both in cables and airborne).


The difference can be both heard and seen!   Watch the film clip from the oscilloscope TIME: 45 sec

 FO Sinus generates no switching noise in the motor. This results in a silent environment.

Compare with PWM* –  PWM technology generates a high-frequency switching noise in the motor which is very irritating for both people and animals.


Sinus Switch – this is how it works: The switch connection in every motor phase consists of two transistors, a coil and two capacitors as well as logic controllers and regulators for control.

The transistors switch so that the current waveform in the coil is triangular, switching on at zero current (i.e. soft switching) and off at full current. The capacitors function as a buffer so that the current going to the motor remains even.

A regulator in the switch circuit estimates the transistors’ timing so that the voltage to the motor equal its sinusoidal set Point.

 PURE SINUS WAVE – the optimum technology for controlling motors!