Controlled Power Technologies at SMMT test day
CPT first with 12V belt-driven Integrated Starter Generator for cars with diesel engines
Controlled Power Technologies has developed the first belt-driven Integrated Starter Generator (B-ISG) to use a conventional 12-volt vehicle electrical system with the high power output necessary to provide excellent stop-start functionality on the majority of European cars equipped with diesel as well as petrol engines. The CPT SpeedStart B-ISG system can deliver up to a 5 per cent reduction in CO2 emissions over the New European Drive Cycle when integrated into a modern powertrain, with the potential for even greater savings in real world urban driving situations.
A major innovation in the SpeedStart system is that it is engineered to be powerful enough to start a 2-litre common rail diesel engine in almost half the time required by a normal starter motor (0 to 750rpm in less than 400 milliseconds against typically 750 milliseconds) yet avoids the need for expensive super capacitors and retains a vehicle's standard 12-volt electrical system. To deliver this performance, the SpeedStart B-ISG's machine technology has been optimised for powertrains with petrol engine displacements up to 3.0-litres and diesel engines up to 2.5-litres, depending on the application.
To demonstrate this capability CPT has installed its SpeedStart B-ISG system in a Volvo S40 demonstrator vehicle equipped with a 2.0-litre diesel engine, which is available for journalists to drive at the annual SMMT test day. It is the first time the company has taken part in this event and its engineering director Guy Morris will be available to discuss the technology and other CO2 reducing initiatives being pursued by the company.
"Our stop-start machine delivers class leading performance even with more challenging diesel applications," says Morris. "The CO2 benefit of stopping an engine while the vehicle is momentarily stationary is obvious, but the re-start must be near instantaneous to instil the high level of confidence that a driver rightly demands. The SpeedStart control system has an excellent stop-start strategy that maximises the full potential of a stop-start system in real world urban driving conditions – such as crawling in heavy traffic. The system consistently delivers an almost silent, instantaneous starting event from a single compact unit, and we've successfully and repeatedly cranked this 2.0-litre diesel powertrain under a wide range of operating conditions. The additional benefit of the CPT machine's low speed generating capability means that the maximum advantage can be gained from intelligent regenerative charging during vehicle decelerations.
"CO2 reduction is necessarily being pursued by every car maker, while every motorist seeks to reduce their fuel consumption. Stop-start is a very cost effective way to gain significant CO2 reduction whilst also offering real world fuel economy and environmental benefits under typical urban conditions. Relatively simple integration with an existing diesel powertrain means that high volume carmakers can now consider introducing the system mid-cycle of their production plans."
The CPT SpeedStart device is a liquid cooled switched reluctance (SR) electrical machine, coupled to state-of-the-art power electronics all contained in a single housing. The CPT SpeedStart device was designed to use SR motor technology from the outset. It offers simple motor construction, accurate control and very high power density and efficiency. During back-to-back comparisons with permanent magnet machines, the SR package came out on top in all key areas says CPT. Working with SR specialists, world class design and manufacturing experts, the motor has matured through product development into a 'very robust production-ready plug-and-play component'.
The CPT SpeedStart B-ISG uses a patented liquid cooling system that keeps both the motor windings and the power electronics under tight thermal control. The high performance and power output demands a high electrical current which requires a guaranteed cooling medium; something that ducted air cannot achieve under extreme ambient conditions. The coolant simply comes from the normal engine cooling system. Liquid cooling offers several advantages over ducted or forced air. It provides a very stable environment for power silicon devices. It does not suffer from water and dirt ingress like traditional air cooled, claw pole machines. The packaging is simpler, as there is no need to provide directed cool air from the front of the vehicle.
"Our principle aim is to deliver green vehicles that the motorist will enjoy driving, without stress or distraction," says Morris. "We have combined robust electric motor technology with affordable state-of-the-art electronics that complement existing vehicle electrical and control systems to achieve a better driving experience, whilst also reducing fuel consumption and CO2 emissions."
CPT was formed just two years ago as a management buy-in funded by private venture capital. It employs a highly qualified team of automotive engineers with expertise in powertrain engineering, power electronics and control software, whose combined experience and skills have been gained through working on micro-hybrid developments and applications throughout the industry. The company is backed by a number of prominent investors specialising in the energy and environmental sectors.
CPT is currently engaged with a number of vehicle and engine manufacturers and more than a few applications are now moving close to production readiness. The company is also developing collaborations with other global technology leaders to extend the benefits achievable. CPT's initial automotive product applications are being followed up by a highly advanced exhaust energy recovery system now in the early stages of development.