Kevin Parmenter, PSD Contributor
The world has a bottomless appetite for energy – and electrical energy is no exception. Of the electricity generated, it’s estimated that approximately 45% of electricity is used to power motors. Compare this to lighting, which accounts for about 19%, even with LED lighting making a significant impact in this area. The biggest offenders are motors often used in pumps and refrigeration.
Anything that can be done to improve the conversion of electrical energy to mechanical energy that results in less wasted heat is a welcome improvement. In addition to driving new applications, more efficient motor drives can help reduce the need to consume limited resources and build more power plants.
It was my privilege to recently moderate a panel session at APEC 2017 that debated the need for additional topologies for the future. The conclusion: more topologies are coming. Due to cost reductions in power electronics we can use variable speed motor drives and power electronics to drive different types of motors designed for various applications – and target them specifically for each application.
We can use electronics to drive fractional horsepower motors in appliances, which until recently used only low-cost AC induction motors. We can also use electronics in HVAC systems that up till now relied on low-cost, single-phase AC induction motors – including the start-and-run capacitors with their associated losses and horrible power factor that goes along with them.
Today’s electronics often yield improvements in efficiency and noise reduction. On the higher end of the motor spectrum, in single, multiple and even higher-horsepower motor drives, we’re seeing variable-speed motor drives being used. However, with decreasing costs for electronics, along improvements in switch technology, adding more switches to topologies is now possible. This enables multiphase motor drive topologies that come without the restrictions of the past. Look for more switching elements in topologies going forward is the message.
Not only have semiconductor switches improved, passive components, such as capacitors for energy storage, are also getting better. Motor drives used for the electrification of transportation is growing, with cars, buses, trains, planes and boats – all types of transportation in the air land or sea – going electric. Improved components can address the hostile outdoor and automotive environments where the electronics must survive for years of reliability.
What does this mean for the makers of power electronics components? I predict a bright and expanding future in all manner of applications in motor drives, from small to huge. Silicon carbide and improved silicon IGBTs and MOSFETS will be the defacto standards. Better mixed signal interface ICs also will be popular.
At APEC, I also chaired a session on isolation barriers. The discussion focused on off-line, high-voltage (120-480 VAC and higher) applications with gate drive isolation, which will be key, both for integrated and in discrete forms. Motor drive makers and design engineers with the skills to develop these systems will have to be bright indeed. As control electronics becomes more digital, knowledge of not only power electronics but control algorithms will be in high demand. With a 32 bit ARM processor costing less than a candy bar, and with the cost of FPGAs coming down, the digitally controlled motor is becoming ever more commonplace as well as possible in wider applications.