Soft Switching Technology
FINCOR ELECTRONICS ADJUSTABLE SPEED DRIVES 5700 & 6600
SOFT SWITCHING TECHNOLOGY
Technology to control the speed of AC motor continues to develop at a fast pace. Adjustable frequency drives (AFDs) are a significant part of this development. Energy savings, less wear on the mechanical components, and better process control are the primary factors which push the rapid advancement of this technology.
Today’s AFD technology with a pulse width modulation (PWM) microprocessor based algorithm, uses insulated gate bipolar transistor (IGBT) to generate the variable voltage and frequency required to control the speed of AC motor. Since IGBT devices can switch at high carrier frequencies (up to 15Khz), there are several advantages:
- More low speed torque for applications where nominal motor torque is required close to zero speed.
- Quieter motor operation which reduces audible noise
- Improved low speed stability which minimizes low speed oscillations.
Unfortunately, fast switching IGBT technology also generates a very fast voltage rise (dv/dt) in the output waveform which induces additional stress on the motor insulation.
Pulse Width Modulation