Turntide Technologies says its Smart Motor System, which is based on switched reluctance (SR) technology and smart power electronics, will not only save money and minimise maintenance, but will also help tackle climate change. According to CEO, Ryan Morris, replacing all motors in every building with smart motors would reduce global carbon emissions by 2.3 gigatonnes a year, which he explains is “the same as adding seven Amazon rainforests to the planet”.
SR motors were patented more than 100 years ago. Unlike brushed DC motors, power is delivered to the stator windings rather than the rotor. This means mechanical design is simplified but electrical design is complicated and requires a separate electronic control system. Practical use of SR motors has been limited owing to various motor and control issues. Until now.
Pros and cons
“While our modern motors are founded in a very old technology, it’s inherently cost effective,” says Piyush Desai, vice-president of motor design and co-founder of Turntide Technologies. “There are no magnets or windings on the rotor which means it’s very cheap to make, robust and fault tolerant.
“SR motor phases are independent and don’t have a lot of mutual inductance. If you lose one phase, you can still operate moderately with reduced capabilities. It’s not smooth and it’s not fully capable, but it will limp you home if it were in your car, for example, unlike induction motors or permanent magnet motors which you’d have to shut off.”
Dave OudeNijeweme, head of technology trends at the Advanced Propulsion Centre (APC), says: “SR motors can work but they do have some issues, including torque fluctuation. This effectively calls for better power electronics to deal with that.
“It’s not something that we see as a major issue; it adds complexity, and you need to know what you’re doing, and it may also add cost on the power electronic side to deal with torque fluctuations. This is a problem the automotive industry is used to mitigating. Some of the same control software used to manage cylinder deactivation is starting to be implemented for motor control and could really benefit SR motors.”
According to Desai, in non-linear systems like SR motors it’s possible that small changes could have a huge impact on performance. This makes them difficult to design. Classic design tools cannot efficiently deliver an optimised design because of this non-linearity and strong dependencies on controls, so they must be designed with numerical iterative techniques such as finite element analysis.
“Motor control is even harder,” Desai adds. “You need to precisely know when and how much current is applied to various motor coils. Without that you have a beautiful machine that’s highly efficient, but you will not get the performance out. Turntide has developed intelligent motor control algorithms for sensorless operation of our Smart Motors that address most known issues with SR motor technology such as poor efficiency, noise/vibrations, and torque fluctuations.”
Desai says that induction motors have historically had higher uptake as they are easier to design and operate and don’t need a separate controller. Plus, environmental factors were not such pressing concerns until recently.
OudeNijeweme says that the APC is beginning to see wider applications for SR motors: “Non-permanent magnet machines including SR motors have been called out as a potentially viable option for a lot of the applications that we’re looking at for electrified propulsion.
“But Turntide is not alone. SR Drives in the North East, now owned by Nidec, has been selling these motors for a long time, and Advanced Electric Machines, a spin-out from Newcastle University led by Professor James Widmer, is scaling up its SR technology. BMW and Jaguar Land Rover have partnered to produce SR motors for their larger vehicles. Another is Punch Powertrain – they’re looking to develop SR machines.”
Desai believes that inductance motor technology is saturated after 130 years, and it will be harder to improve efficiency without using expensive materials and processes. The alternative could be reluctance-based technology including synchronous and SR that are free of rare earth minerals.
OudeNijeweme explains: “At this moment, permanent magnet machines tend to be more efficient over a bigger area of their operating window than SR machines. But, because of the nature of permanent magnet machines, you can’t push them too hard as they rapidly lose performance as temperature increases.
“The biggest issue though is that the neodymium, terbium and dysprosium used in these magnets comes from China. Security of supply came under threat in 2010-11 and it will again. A relatively small number of large companies based there are producing magnets at price points that are below what western companies can match. This is primarily due to local iron-ore mines that extract rare earths including neodymium as a by-product, highly vertically integrated supply chains combined with low labour rates and differing standards.
“Automotive companies have always been good at designing themselves out of that sort of trouble and that may mean designing motors without magnets.
“Sintered magnets could be the only way forward for wind turbines, their generators have to have magnets. Wind turbines and cars are the biggest growth markets for magnets.”
SG Technologies, in Rainham, makes magnets for solenoid injectors for Tier One companies and OEMs as well as for consumer products. It makes magnets in a novel way, forming them in one part in a net shape, sometimes in very intricate, efficient designs with no loss. They are typically neodymium-iron-boron and devoid of dysprosium and terbium (very heavy rare earths) that make the magnets more resistant to high temperatures. This is seen by the APC as an intermediate piece of the puzzle that could be an alternative to fully sintered magnets for pumps, heating, ventilating and air conditioning (HVAC), seat motors, and potentially for traction motors.
But Desai says permanent magnet motors won’t be cheaper to manufacture owing to the cost of the magnetic materials and the sensitivity of their supply chains.
“The conditions are better now because there is a strong pull from the market about energy efficiency,” he explains. “Not using rare earth materials, the cost of electricity rising, climate change, sustainability, pollution, carbon emissions, they’ve all become mainstream concerns. Tools for designing an optimal SR motor system are now easily available, more affordable and more powerful.”
He adds: “Another tailwind for SR motor technology is in the power electronics. Silicon devices are always improving in performance and class. What was an issue 30 years ago around the cost, reliability and availability of electronics isn’t any more. On the contrary, many induction motors are now installed with power electronics and drives.”
Turntide has been able to pack more copper in its stator coils, which has increased efficiency. That, combined with the firm’s proprietary motor design and control technology, means that its SR motors are highly efficient over a range of torque and speed. This has opened up new applications for its Smart Motors, such as air handling in fans and blowers.
Desai explains: “The beauty of these applications is that the power is proportional to the cube of the speed. If you reduce the speed by 50% the power is now one eighth. Turntide’s Smart Motors, with their high efficiency over a wide range of operating conditions, can produce tremendous savings for customers when driving a variable load.”
Often, HVAC systems are designed to deliver maximum power at maximum speed, but they often operate at lower speeds and so at lower power. Where fixed-speed induction motors aren’t operating at rated conditions, efficiency reduces dramatically. Desai says Turntide’s SR motors are 10-30% more efficient in these circumstances.
This, in part, is owing to high-efficiency motors and optimised control, but also to the Internet of Things element, which records and monitors data analytics and makes this available to building managers who can then tune the system optimally.
Turntide has attracted $400m in funding from investors such as Microsoft founder Bill Gates’ Breakthrough Ventures, actor Robert Downey Jr’s Footprint Coalition, Amazon, and iPod inventor Tony Fadell.
It has also conducted a range of case studies including with restaurant franchise Five Guys, where its Smart Motor System was retrofitted to the HVAC system at a restaurant in Montgomery, Alabama, achieving 70% energy savings over four weeks of use. Another, at a global biotech company’s HQ in San Francisco, California, saw the Smart Motors again retrofitted to the HVAC system, delivering 63% energy savings as well as increased operational reliability and better predictive maintenance through data collection.
Turntide recently acquired three North East-based businesses, including the drives division of Gateshead’s BorgWarner, Sunderland’s Hyperdrive and Northumberland’s AVID, which are all involved in the electric transport sector. This will allow Turntide to enter the freight, heavy equipment, construction equipment, aviation and rail markets.
OudeNijeweme says: “All three UK companies have received support through APC funding. Turntide offers them a fantastic opportunity which may prove the big investment that enables the scale up to Tier One status. I’ve got high hopes.”
These acquisitions have been facilitated by electric vehicle expert and professor at the University of Newcastle, Matt Boyle, who says: “This is part of Turntide’s multi-year investment in the North East, known for its innovation in the electrification industry, allowing a smooth path to sustainable transport.”
Desai concludes: “SR technology is the future. It won’t replace everything; our goal is to replace a big portion of lower efficiency, highly polluting technologies with an optimal motor system.”
OudeNijeweme has a less radical view: “I think SR motors will occupy around 20% of the automotive market share – I would expect this to be within the larger-vehicle passenger car segment and the heavy-duty sector where reliability is key.”
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