|Left: The SpeedStart B-ISG. Right: Installation in Volvo demonstrator with INA damper. Source: CPT. Click to enlarge.|
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 gasoline engines.
The CPT SpeedStart B-ISG system can deliver up to a 5% 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.
Controlled Power Technologies (CPT) is a UK startup working with switched reluctance motor technology to deliver cost-effective CO2-reducing solutions for vehicles.(Earlier post.)
The CPT SpeedStart device is a liquid-cooled switched reluctance (SR) electrical machine, coupled to 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.
The patented liquid cooling system 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.
A major innovation in the SpeedStart system is that it is engineered to be powerful enough to start a 2-liter 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 optimized for powertrains with gasoline engine displacements up to 3.0-liters and diesel engines up to 2.5-liters, 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-liter diesel engine.
The SpeedStart control system has an excellent stop-start strategy that maximizes 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-liter 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.—Guy Morris, Engineering Director