KEYNOTE PCIM 2021: Variable speed drives and next-gen inverter concepts
Variable speed drives are widely used in industry and infrastructure applications and play a crucial role in regulating current in motor-based systems such as heating, ventilation, and cooling. In a bid to solve efficiency problems, researchers are turning to SiC/GaN to boost performance.
Variable speed drives (VSDs), sometimes called variable frequency drives, are a valuable energy management tool. A typical VSD system is made up of a three-phase alternating current (AC) induction motor and a variable frequency power supply which uses solid-state components to create a pulse-width modulated current which varies the power and frequency supplied to the motor in an application, such as a HVAC system. In short, a VSD allows for accurate control of motor speed over a broad range.
Current VSD systems are highly inefficient
While current VSD systems work well in practice, they are incredibly energy inefficient when compared to other modern power electronics systems. According to Hitachi ABB, 70 % of electricity that is currently consumed by industry worldwide is used in electric motor systems, and in your average commercial building, this figure is 38 %. Worldwide, 45 % of all electricity is used for motors in buildings and industrial applications. It goes without saying therefore that there’s a growing need to make VSD systems more efficient, and a significant amount of research effort takes place each year, and public research university ETH Zurich is heavily involved.
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Next-generation variable speed drive systems
On Tuesday May 4, 2021, Professor Johann Kolar of ETH Zurich presented a keynote titled Next-Generation SiC/GaN Three-Phase Variable-Speed Driver Inverter Concepts at PCIM Digital Days 2021, the digital industry meeting place for international power electronics.
Current VSD systems are largely built on silicon (Si), however Professor Kolar highlights how employing the latest ultra-fast switching wide-bandgap (WBG) power semiconductors, gallium nitride (GaN) and silicon carbide (SiC) will help to enable improvements in VSD performance. Namely, use of GaN/SiC in high-frequency pulse width modulation (PWM) in motor drive applications help to deliver high motor efficiency, lower torque ripple, and smaller filter size, among other advantages by enabling operation at high switching frequency. It also helps to reduce voltage reflection and motor insulation breakdown issues.
Watch the whole keynote here:
During the keynote, Professor Kolar highlighted how next-gen VSD systems should feature high power density, get rid of the requirement for shielded motor cables, offer an input/output voltage and/or motor speed range, and ensure low motor power losses. He also highlighted how these next-gen systems should feature cognitive functionality for a seamless integration in Industry 4.0 environments.