Controlled Power Technologies Heading to Commercialization of Switched-Reluctance Motor Systems for Vehicle Efficiency
|Design evolution of the production-ready VTES. Click to enlarge.|
Controlled Power Technologies (CPT), a UK startup working with switched reluctance motor technology to deliver cost-effective CO2-reducing solutions for vehicles (earlier post), is progressing toward commercialization of three initial products: Variable Torque Enhancement System, VTES, an electric supercharging system; SpeedStart12, an integrated belt-driven starter generator system; and TIGERS (earlier post), an exhaust turbine-driven generator system.
All three products, acquired from Visteon, employ switched reluctance motors. Controlled Power Technologies secured an exclusive license from Switched Reluctance Drives Limited to develop its electric motor technology for the automotive sector. SR Drives is a UK company based in Harrogate and wholly owned subsidiary of Emerson Electric Company.
|VTES schematic. Click to enlarge.|
VTES is the closest to commercialization, and is ready for high-volume production, according to CPT. Guy Morris (formerly of Visteon), the company’s engineering director and chief technical officer presented VTES to the Advanced Charging & Downsizing Concepts Congress in Stuttgart, Germany, earlier this month.
VTES is a compact, forced induction torque enhancement system using a compressor driven by an air-cooled switched reluctance motor, which achieves high power density to deliver high airflow and efficiency. The motor operates using existing 12-volt electrical systems.
The fully programmable product is designed for integration into both gasoline and diesel engines. The design has been optimized to achieve effective engine boosting when used on its own or in conjunction with a standard turbocharger.
VTES offers maximum boost pressure of 0.45 bar, with a maximum speed of 70,000 rpm.
When optimized, VTES can dramatically increase the engine air charge density over the first 10 combustion cycles of a low speed transient operation, hence enabling real improvements in both torque and emissions performance, where it matters most.
Looking ahead, this technology also has the potential for energy recovery during throttled operation of gasoline engines. The motor can switch to generator mode almost instantly, the compressor can be configured as a ‘cold air’ induction turbine with efficiencies of more than 50 percent being possible, while power levels greater than 150W can be readily generated at 14 volts.
For fuel cell applications we’re looking at a 2-stage high voltage (240+ volts) concept delivering approximately 4kW of stabilised power offering a more compact, lower mass and lower noise system than other solutions.—Guy Morris
|The SpeedStart12 starter generator system. Click to enlarge.|
SpeedStart12 is not quite ready for application, according to CPT, but not far behind VTES in development. SpeedStart12 is a fully integrated belt-driven starter generator system, including all control and power electronics, featuring a liquid-cooled switched reluctance motor.
SpeedStart12 is optimized to use standard 12V vehicle architecture. To ensure compatibility with most modern European powertrains, production intent hardware has been carried out predominantly on a European 2-liter common rail diesel engine, although the product is designed for integration into both gasoline and diesel engines.
CPT is targeting a 5% reduction in CO2 on the NEDC from stop-start functionality, with an additional 3-5% reduction from optimized high-power regeneration during decelerations. Nominal cranking power is 2.2 kW, and continuous generation power is 2.7 kW. Low engine speed generation power is 2.0 kW, and typical generation efficiency is 80%.
|Design scheme for TIGERS. Click to enlarge.|
TIGERS—Turbo-generator Integrated Gas Energy Recovery System—has been under development since 2004 and was partly funded by the UK government Foresight Vehicle initiative to establish a proof-of-concept.
In the TIGERS system, a small switched reluctance turbo-generator is installed in a by-pass waste pipe fitted just below the engine exhaust manifold. A valve linked to the engine’s management control system allows some of the high-energy exhaust gases to pass through a turbine to drive the generator, depending on engine load conditions.
Typically the 800º C exhaust gases have a velocity of 60m/s and a mass flow rate of 0.05 kg/s, providing enough energy to spin the generator at up to 80,000 rpm and create electrical power of up to 6kW—sufficient to handle the car’s electrical systems.
So far, CPT has met a number of milestones with TIGERS, including engine and vehicle simulation; system concept designs; control system design and simulation; proof of concept detail design and component manufacture as well as engine baseline testing.