A variable frequency drive or frequency converter is a type of motor controller that drives an electric motor by varying the frequency and voltage of its power supply. It is also able to control the start and stop of the motor during starting and stopping.
Even though the drive controls the frequency and voltage of the power supplied to the motor, we often refer to this as speed control, as it involves adjusting the speed of the motor.
There are many reasons why we should adjust the motor speed.
To save energy and improve the efficiency of systems.
For power conversion in hybridization applications
For adapting the speed to the process requirements
For adapting the torque or power of a drive to the process requirements
To improve the working environment
For a lower noise level, for example in fans and pumps
For reducing the mechanical load on machines to extend their service life
For reducing peak load to avoid peak demand prices and to reduce the required motor size.
In addition, today's AC drives integrate networking and diagnostic functions to better control performance and increase productivity. So energy savings, intelligent motor control and reduced peak current consumption are three good reasons to choose a variable speed drive as the control in any motor-driven system.
The most common applications for a variable speed drive are the control of fans, pumps and compressors. These applications account for 75 % of all drives operating worldwide.
Soft starters and mains-operated contactors are other, less demanding types of motor control. A soft starter is a semiconductor device that enables a soft start to full speed when starting an electric motor.
A mains-operated contactor is a motor control that applies the full mains voltage to an electric motor.
For more information, see "BLEMO Products". We offer both single-phase and three-phase frequency converters.
Further information about BLEMO softstarters
What is special about BLEMO frequency inverters?
BLEMO is a manufacturer specialized in frequency converters and softstarters. You will receive an extremely high quality frequency converter, which is individually tailored to your requirements. Every single frequency converter undergoes extensive testing before leaving the factory. Our experts focus on every detail of drive optimization and are always up to date with the latest technology. The latest developments are often to our credit. BLEMO has a wide range of frequency converters and softstarters, but you get much more than the frequency converter. You have access to our application know-how and various maintenance services to keep your systems running optimally throughout the entire life cycle of your frequency converters.
We offer you the best possible components and full flexibility so you can tailor system performance to your application. An important aspect of this flexibility is the ability to use your frequency inverters with all common motor technologies. This allows for significant savings in spare parts inventory and retrofitting.
What is the main advantage of using frequency inverters?
A variable speed drive can vary the power output according to the energy requirements of the driven equipment, saving energy and optimizing energy consumption.
The AC drive can dramatically reduce energy consumption compared to direct mains operation, where the motor runs at full speed regardless of demand. The use of a variable speed drive typically achieves power or fuel savings of 70%. The roll-on effect means that using variable speed drives also reduces NOx emissions from the systems in which they are installed and improves their carbon footprint.
What is the difference between a variable speed drive, an AC drive and a variable speed drive?
There is none. All these names refer to the same device.
Frequency converter types
There are many different types of frequency converters as they are widely used in industry. There are both single-phase and three-phase frequency converters for a wide range of applications. Among the differences between the different types of AC drives are the different methods of frequency and voltage control and the technologies used to reduce harmonics.
The three main variable frequency generation techniques used in AC drives are pulse width modulation (PWM), power source inverters and voltage source inverters. The PWM technique is the most common. PWM technology requires that the inverter power electronics of the frequency converter - transistors or insulated gate bipolar transistors (IGBT) - generate the correct voltage level by constantly switching on and off. By controlling and varying the pulse width, pulse width modulation changes the output frequency and voltage