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Controlled Power Technologies Packages Its Switched Reluctance Systems in ‘RegEnBoost’ System for Enhanced Support for Downsizing

The three components of the RegEnBoost system. Click to enlarge.

Controlled Power Technologies (CPT) is packaging its three complementary switched reluctance machine-based systems—a fast-acting electric supercharger known as VTES (or variable torque enhancement system) (earlier post), a highly efficient liquid cooled integrated starter generator (ISG) known as SpeedStart (earlier post), and an advanced turbo-generator integrated gas energy recovery system known as TIGERS (earlier post) in a novel engine-boosting and power regeneration concept it calls ‘RegEnBoost’.

CPT says that the RegEnBoost system enables a typical family-sized car to achieve less than 100 g/km CO2 with a 1-liter gasoline engine, but when required can offer the same lively performance and in-gear acceleration of a 2-liter naturally aspirated powertrain. This CO2 level is comparable to that emitted by equivalent sized full hybrid vehicles, yet avoids their need for high voltage and the significant impact a hybrid’s large batteries and traction motors have on overall vehicle cost, mass and packaging.

RegEnBoost integrates the three devices into a powertrain electrical power network (PEPN), which also incorporates a DC to DC converter and an enhanced lead acid battery, optimized for fast energy storage and release. The combination of electronics, advanced battery technology and charging techniques ensures the system can deliver the required rapid charge and discharge performance, while at all times maintaining a stable 12 volts to the vehicle’s main electrical system.

The concept ensures long term energy storage for delivering short bursts of power to the VTES supercharger during vehicle accelerations and to the SpeedStart stop-start device during engine re-starts. Conversely, short bursts of power can also be absorbed by the SpeedStart generator to recharge the battery during vehicle decelerations. Power for the battery and VTES electric supercharger is not only supplied by the SpeedStart ISG but also the TIGERS exhaust driven turbo-generator. The electronic controls supervise the optimal switching between the SpeedStart and TIGERS electrical generators according to driving conditions and regenerative power availability.

A deep understanding by the CPT engineering team of the power and control electronics embedded within all three devices and the essential characteristics of the interconnecting network helps underpin the overall efficiency of the system, which in essence facilitates radical downsizing of gasoline and diesel engines without compromising vehicle performance.

Small displacement engines offer excellent CO2 and fuel economy benefits; they have lower parasitic losses and operate more efficiently under part load conditions. Small engines can also be turbocharged to deliver comparable torque and power to a larger naturally aspirated engine. However, with a conventional turbocharging system, the turbine size necessary to maximize efficient high speed performance gives unacceptable low speed response, which affects the driveability of the vehicle. Hence the industry trend to dual-charging systems, CPT notes.

The boosting element of CPT’s technology, which addresses this issue, is derived from the VTES electric supercharger, which can be installed in series with a simple fixed geometry turbocharger. Unlike a crankshaft driven mechanical supercharger or an additional exhaust driven turbocharger, the CPT method of boosting is completely independent of engine speed and offers precise electronic control. No matter how low the engine revs, the 2 kW electric supercharger remains highly responsive and extremely fast acting. This crucial difference means the technology is perfectly suited to maintaining vehicle performance and driveability—widely recognized as a critical marketing issue for any car maker contemplating radical engine downsizing.

Another key element of the RegEnBoost concept is delivered by CPT’s SpeedStart device, which outperforms existing designs of starter motors and alternators in almost every respect, according to CPT, providing an advanced 3kW stop-start solution that is more powerful, more efficient and more usable than first generation systems.

It’s the first design to integrate all the power and control electronics into a single electric motor assembly and by maximizing the number of stop-start events the system aims to significantly reduce fuel consumption and CO2 emissions. For the RegEnBoost concept it provides a vital additional role not only in terms of its advanced stop-start capability, but also for its potential in energy recovery and electrical regeneration under braking. This in particular helps the VTES electric supercharger boost the engine for acceleration without incurring a CO2 penalty.

A final key element of the RegEnBoost concept is the TIGERS turbo-generator. Coupled to an exhaust-driven turbine the second generation 2 kW air cooled device is intended to generate electrical power during high speed acceleration and steady state cruising, when it can more efficiently deliver electrical power than the SpeedStart device, which can therefore be temporarily powered down.

Exhaust gases provide an efficient and as yet unutilized method of power regeneration, particularly for a throttled gasoline engine, and further helps improve fuel economy and reduce CO2 emissions. The TIGERS system includes an electronically controlled full flow by-pass that ensures the desired proportion of exhaust gas is delivered to the turbo-generator as determined by the control system.

All three devices in the RegEnBoost concept are based on high efficiency switched reluctance (SR) electrical machines which, because of their flexibility, can be readily scaled to support engines up to approximately 3.5-liters capacity. Significant advantages include the simple construction from steel, aluminium and copper (avoiding precious rare earth materials), accurate control, very high power density and in excess of 80 per cent efficiency. A major part of CPT’s effort has concentrated on optimizing the technology for automotive applications and establishing a manufacturing strategy and supply base. World class manufacturing partners have already been identified.

VTES, SpeedStart and TIGERS are all fully-integrated standalone devices each highly effective in their own right, but their combination provides for a high level of synergy where careful management of energy flow offers potential efficiency gains greater than the sum of the individual parts. Moreover, there is very little modification to the base engine design enabling vehicle manufacturers to apply the system—or its individual components—at much lower cost than a full hybrid vehicle.

—Geoff Morris, CPT’s engineering director and chief technical officer

Low Carbon Vehicle Partnership Technology Challenge. CPT presented the RegEnBoost system as one of six emerging UK businesses to get the attention of senior automotive executives at a unique event organized by the Low Carbon Vehicle Partnership (LowCVP). The opportunity to pitch ideas directly to 16 major vehicle manufacturers and Tier 1 suppliers is the culmination of the LowCVP’s Technology Challenge; an industry initiative to help fast track innovations being developed by small- and medium-sized companies.

We’re delighted to be among the Technology Challenge winners and for this unique opportunity to present our RegEnBoost engine-boosting and power regeneration concept to so many carmakers at one fell swoop, also for the huge interest they’ve taken in this LowCVP initiative. Normally it would take months of effort to meet this number of vehicle and component manufacturers.

—Guy Morris

Inspired by the recommendations of the New Automotive Innovation and Growth Team (NAIGT) published May 2009, the LowCVP event sets out to create closer collaboration between the developers of new technology and the mainstream automotive industry. The event is being chaired by Professor Richard Parry-Jones, the newly appointed chairman of the recently established Automotive Council.

CPT was selected on a competitive basis from 17 entries covering widely varying technical innovations. The final selection of six companies by an expert panel was based on the merits and impacts of their technology for reducing vehicle CO2 emissions. Important criteria included their alignment with the NAIGT technology roadmap, commercial viability and ease of integration.

The other five winners of the challenge were:

  • Axon Automotive has a lightweighting solution for vehicles structures. Usually limited to use as panels, the company has developed a unique process for creating structural components from carbon fibre. They have also designed a 100 mpg UK (83 mpg US, 2.8 L/100km) plug-in hybrid scheduled for production in 2011. Formed in 2006, the company is a spin-out from the Honda Ecotechnology Centre at Cranfield University. It comprises materials experts and vehicle designers as well as body and powertrain engineers.

  • Brunel University has a novel regenerative engine braking technology known as ‘RegenEBD’ which utilizes a vehicle’s engine under braking to compress air for energy storage, engine stop-start and boost assist. Suitable for cars, buses and commercial vehicles, the technology’s development has been led by Professor Hua Zhao, director of the University’s Centre for Advanced Powertrain and Fuels at the University’s School of Engineering and Design, Uxbridge.

  • EVO Electric Limited, is a 2007 spin-out from Imperial College London to develop advanced electric machines and drive systems based on its proprietary axial flux technology. Axial Flux motors and generators are characterized by very high torque and power density. Based in Woking their flagship product, the Axial Flux Motor, is designed to meet the requirements of electric and hybrid vehicles with the technology applicable to all vehicle classes.

  • Libralato Engines is commercializing a compact, optimized type of rotary engine, ideally suited to operate in hybrid electric vehicles. Having unique, asymmetrical compression and expansion geometry, the Libralato engine has only four moving parts and is primed to deliver a step change in thermal efficiency.

  • Oxy-Gen Combustion delivers a solution to real deployment of Homogeneous Charge Compression Ignition (HCCI) engines and Controlled Auto-Ignition (CAI), technologies which have been widely touted in the future road map of the automotive industry for their low emission and fuel savings characteristics. Unlike hybrids these technologies do not require a change in the vehicle or engine architecture.



The idea of using recovered brake energy to power a supercharger seems pretty good, but I would assume that recovered energy would be better used going straight to the driveshaft using the same motor / generator that it was recovered from.

Start / stop should have been mandatory on all cars 5 years ago, helps urban mpg and allows pulse and glide / coasting for higher highway milage.



You need much less energy supercharging electrically your engine than boosting it directly.
Figures are about:
8 kJ for a 3 second VTES boost
30 kJ for a 3 second direct boost via the ISG

That's why they do it that way.

Of course, the advantage of boosting directly is that you save fuel, whereas electrically supercharging only achieves fuel economy through possible downsizing of the ICE.




It like the electric turbocharger idea. If you combine that with a BAS and use it more aggressively, you can save fuel. You downsize the displacement and boost when you need to with better response. Other times you are putting the energy into batteries for the next acceleration.

This is a combination that could work on almost any smaller car and be retrofitted. Would people pay five thousand dollars to upgrade a five year old compact to get 30% better mileage...I don't know. If gasoline is five dollars per gallon and they could save one thousand dollars per year on fuel for a five year payback...maybe.


This is amazing in its ingenuity; note there's nothing exotic or unproven in the technology. Reliability/durability should be great since the underlying ICE, while smaller, is unchanged. Should be easily integrated into OEM manufacturing. You could see this take off in europe.
I'm curious as to the overall effect on fuel consumption as they don't provide any figures. In theory, low carbon output should mean high fuel efficiency.

Nick Lyons

This is great: practical, low-cost, high-return. Add these to a small displacement direct injection gasoline engine and you could probably get 40-50mpg from a compact/midsize car with minor incremental cost and no hybrid compromises on interior space or worries about battery life.

The real question is: which auto company will be willing to buy this NIH technology?


They might get some low volume buyers in the automaker world that do not want to develop their own. Couple that with some retrofits and they might actually have a market. A 4 cylinder Camry or Altima could benefit from an electric turbo and BAS. They do not have a lot of pick up so better zip and mileage could be attractive.

Henry Gibson

I played with a switched reluctance toy motor as a child, but ten years ago found that modern ones have many advantages including weight, efficiency and cost. Power electronics have been developed to the point that the machines may also have low investment costs in addition to high operational efficiency.

Diesel engines are more suited to high pressure supercharging and are more efficient. Diesel fuel is cheaper and more CO2 efficient to produce from crude oil, and it is actually logical to require the use of diesel engines in most vehicles. Two stroke diesel engines with electric supercharging can have very high specific power for automobile engines. MITI developed a combined turbo-electric-supercharger years ago.

Engines have been perfectly adequate for automobiles for over a century, but it is the transmission to the wheels that needs work. George Constantinescu provided a cheap simple method to use small engines to provide high torque, and the same can be done in other ways including electric, air and hydraulic hybrids.

EFFPOWER, Firefly and others have shown that even lead acid batteries can be engineered to provide adequate service in hybrid automobiles, and modern materials and construction techniques have made this much easier.

TATA and Ford and VW and others have at times nearly eliminated the requirement that automobiles serve as a status symbol in addition to providing transportation to and from local grocerie stores and other facilities. High acceleration and high speeds and high horsepower are not a requirement for almost all automobile trips.

Now it is cheaply possible for all cars to be required to be equipped with a constant indicator of the horsepower being used and the average horsepower of the trip as well as the efficiencies of the engine, so that people can be aware of the lack of need for high horsepower and the related low efficiency of high horsepower engines. ..HG..


A worldwide competition, to design a very low cost ultra high power density (1Kw/1Kg) flex fuel ICE power generator for PHEVs, would be very interesting.

The competition could last 12 to 18 months.

Every G-8 or G-20 industrial country could finance this project at the rate of 10 cents per inhabitants or equivalent.

Of course, no patent wrights would apply. Worldwide producers could obtaine detailed specs and copy at will. This could further reduce mass produced cost.

It would be some kind of an R & D gift from the G-8/G20.

Many goals and winners could be set. Best weight/power ratio, most fuel effective, cleaner or least GHG per Kwh, cheapest to produce, most quiet running etc.


We could start to see some very unique and efficient engines for extended range. The whole application has changed from an engine that has to do everything through a transmission to one that has to do one thing...generate power at a steady load and speed.

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