This series brings topics answering basic questions around VFDs such as fundamental components of VFDs, drive system components, working principles, dimensioning considerations etc.
Drive systems according to their working principle Electric drives have many excellent properties that make them a preferred choice [1]. However, there are other types of drives based on other physical principles that also have their own strengths. In this blog post we compare hydraulic, pneumatic, thermodynamic and electric drives. Read more…
Why is it important to keep reasonable switching losses? Switching frequency is a decisive design parameter of a VFD – especially in medium voltage drives where the semiconductor capability may be more restricted. But switching losses have much bigger impact on the system. The end user shall understand it properly Read more…
LCI celebrates 50 years anniversary! It is little bit hard to believe but the high-power drive champion LCI celebrates 50 years anniversary in 2024. We take this opportunity to look back at the history of this matador and maybe also a little outlook. Birth of LCI in 1974 It was Read more…
What is the difference between soft starter and VFD soft starter? Today we briefly explain a topic that may sometimes confuse: What is the difference between soft starter and VFD soft starter in motor starting applications? Direct on-line motor start Across the line or direct on-line (DOL) motor start is Read more…
What is the best investment in 2024? Beginning of a new year is linked with new goals, ambitions and expectations. In the economic field many people probably hope that the inflation finally drops, the major economies do not fall into recession, unemployment rate remains low and the purchasing power increases. Read more…
What is the optimal pulse number of a diode rectifier? Among variable frequency drives (VFD), the voltage source inverter with a diode rectifier is the most common all-rounder. However, there are several arrangements of the diode rectifier varying in the number of pulses. Is a 12-pulse rectifier sufficient? Do I Read more…
What is the difference between dv/dt filter and sine filter? Almost every voltage source inverter (VSI) has some kind of inverter output filter. Design of the output filter has major impact on the drive characteristic and performance. For this post we have picked two key representatives. They are widely used Read more…
How are the motor load points defined? Customer is often interested in defining the performance (e.g. losses and efficiency) of a motor drive for specific operating points. But how are the motor load points defined? Over the years working with variable speed inverter fed motors I come across this topic. Read more…
What is the definition of low voltage and medium voltage VFD? We all probably know that variable frequency drives (VFD) can be classified into two groups based on their voltage: low voltage VFD and medium voltage VFD. But what voltage do we talk about? Let’s shortly explain… IEC 61800 distinguishes Read more…
What type of asynchronous motor suits the best for VFD duty? Asynchronous motor is sometimes called the work horse of the industry. And this nickname is well earned. It is because millions of such motors are utilized in different applications across the globe. They help the world turning. While most Read more…