Electric Supercharging

These are a series of press releases from Controlled Power Technologies

Controlled Power Technologies was set up in 2007 to acquire advanced powertrain technologies from Visteon Corporation and its technology development partner Emerson Motor Company (EMC), a division of Emerson Corporation.

All CPT technologies have a direct drive ‘switched reluctance’ electrical machine at their core, including the VTES electric supercharger, which has been extensively developed with the benefit of significant OEM input in terms of both system requirements and prototype evaluation.

Currently, permanent magnet electric motors are more commonly used in the automotive industry.  The main advantage of switched reluctance technology for electric motors is their robustness to high operating temperatures, low cost and recyclability.

Switched Reluctance Drives Limited, a wholly owned subsidiary of Emerson Motor Company, based in Harrogate, remains a technology partner for CPT.  SR Drives has granted an exclusive licence for the application of its switched reluctance patents to CPT products for a wide range of automotive applications.

In addition to its electric supercharger, the CPT family of low carbon powertrain related products includes its ‘SpeedStart12’ stop-start system now moving close to production readiness and its ‘TIGERS’ exhaust energy recovery system in an early stage of development.  

Controlled Power Technologies was created as a management buy-in funded by venture capital.   The company comes with the backing of a highly experienced team of automotive engineers and is backed by a number of prominent investors specialising in the energy and environmental sectors. 

• 31 March 2008
• 24 September 2008
• 22 September 2009

Controlled Power Technologies says supercharging is the answer to ever smaller engines 

At a high level international automotive conference in Stuttgart this week Controlled Power Technologies will present the benefits of an innovative electric supercharging system developed for the smaller more fuel-efficient engines being progressively introduced by carmakers to reduce vehicle CO₂ emissions.   

CPT’s Variable Torque Enhancement System (VTES), which utilises ‘switched reluctance’ technology, is ready for high volume production and can be applied cost-effectively to all types of gasoline and diesel engines including those already turbocharged.   

For diesel engines, a near instant air supply enables delivery of high transient torque with minimal particulate emissions, offering potential for significant diesel particulate filter (DPF) downsizing.  The technology also provides potential for energy recovery during throttled operation on gasoline engines and can provide the air supply for future fuel cell electric vehicles currently under development by the motor industry.

Guy Morris, engineering director and chief technical officer, will present CPT’s new technology to an expert audience attending the Advanced Charging & Downsizing Concepts Congress being held at Steigenberger Graf Zeppelin in Stuttgart, Germany.  The three-day international assembly of automotive engineers takes place on Monday 31 March through to Wednesday 2 April 2008.

“From an idea first conceived in the year 2000 this technology has been progressively developed to the point where it is now a mature well-proven second-generation design, ready to be adopted by carmakers,” said Morris.  “Uniquely the supercharger utilises a switched reluctance motor - a technology that is well-proven in other industry sectors but has yet to be applied by the automotive industry.” 

From the outset this new-type of electric motor - applied in this instance as a supercharger with other applications to follow - has been developed with the close involvement of carmakers in order to meet stringent automotive industry standards and vehicle manufacturer requirements. 

“Seven years on and we’ve reached the final stage of product development and production readiness,” says Morris.  “The system offers a high level of vehicle performance because of the significant torque enhancement it delivers at low engine speeds.  The switched reluctance motor, which operates using existing 12-volt electrical systems, is both highly efficient and responsive.

 “Carmakers are especially attracted to the low level of engineering effort when applying the technology and in particular the minimal production investment required.  It’s a small compact system with fully integrated electronics that’s easy to install – it’s virtually plug and play.

“For the motorist it simply means having the economy of a small engine with the performance of a big engine.  For example, in a high gear there is typically a 40 per cent reduction in 70-100kph (45-65mph) acceleration times.  This is worth around seven seconds in a 1.2-litre car with a six-speed gearbox.

“When optimised, 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 per cent 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.”

Controlled Power Technologies was created a year ago as a management buy-in funded by venture capital and recently completed the acquisition of its portfolio of production-ready solutions to the problem of automotive CO₂ reduction.  The company comes with the backing of a highly experienced team of automotive engineers and is funded by a number of prominent investors specialising in the energy and environmental sectors. 

In addition to its production ready electric supercharger, CPT’s family of low carbon powertrain related products includes an application ready stop-start system now moving close to production readiness, and an exhaust energy recovery system in an advanced stage of development.  

The originality in all the products is that they utilise highly efficient ‘switched reluctance’ electric motors; an as yet untapped technology for the automotive sector, but widely used in many other industry sectors for their robustness and reliability.

“Switched reluctance motors are well suited to the requirements of the automotive industry,” says Morris.  “They can be produced for high volume series production at very low cost; they are manufactured mostly from easy-to-recycle steel and aluminium and avoid the use of exotic, expensive and heat sensitive materials.  These compact motors are easy to package and offer excellent energy efficiency and controllability.”

Controlled Power Technologies has secured an exclusive license from Switched Reluctance Drives Limited to develop its unique electric motor technology for the automotive sector.  SR Drives is a UK company based in Harrogate and wholly owned subsidiary of Emerson Electric Company.  A major multinational corporation headquartered in St Louis, Missouri, USA, Emerson is a Fortune 500 company providing engineering services and innovative solutions for customers in a wide range of industrial, commercial and consumer markets and is one of the largest engineering and conglomerate companies in the world.

Controlled Power Technologies ready with electric superchargers for a new generation of cars and their radically smaller engines

Low cost micro-hybrid technology will help reduce fuel consumption and carbon emissions

UK-based Controlled Power Technologies (CPT) says that its electric supercharger known as VTES (or Variable Torque Enhancement System) is now ready for production applications and the company is supporting carmakers with this low cost technical solution to the ever tightening CO₂ reduction and fuel efficiency targets facing the automotive industry.

“The low investment requirements of our electric supercharger provide the opportunity to bring early niche applications to market cost effectively and on multiple vehicle lines,” says Guy Morris, engineering director, CPT, who will present the latest findings of the company’s research, development and testing programme at a special supercharging conference for vehicle engineers being held this week in Dresden on 25/26 September 2008.

CPT says it is progressing a number of confidential development contracts that will lead to commercial applications, initially for small and medium volume production, and will continue to work with the industry’s powertrain developers to verify the benefits of electric superchargers.

“Our electric supercharger is an ideal enabling technology for the extreme engine downsizing being advocated by carmakers,” adds senior engineering manager Mark Criddle, who co-authored the technical presentation.  “The technology has been designed to be sufficiently flexible to enable use of a common solution across a wide range of engine platforms.  It delivers the required economies of scale and matches existing micro-hybrid strategies.”

Extreme engine downsizing typically means replacing a 2.5-litre engine in a full-size family saloon or MPV with a 1.2-litre turbo-charged engine.  A new generation of cars, with radically smaller engines, will be more able to deliver the fuel economy and low CO₂ emissions demanded by legislators and motorists alike.   Increasing the efficiency of the powertrain through extreme downsizing is fast becoming a widely-recognised near term solution for both gasoline and diesel engines. 

Motorists, however, have certain minimum expectations for vehicle performance.  Boosting the charge of air into the engine by mechanical supercharging or exhaust turbocharging is the most effective way to satisfy this requirement, but only if sufficient low-speed transient torque is delivered quickly enough to meet customer expectations for vehicle drivability.  The critical reference point remains the response time of the larger naturally aspirated engine that is being replaced.

Based on naturally aspirated engine characteristics, motorists have come to expect a significant torque rise to be available almost instantaneously.  This means typically within half a second during wide open throttle transients, when engine revs may be less than 1,500rpm.  Although engines equipped with conventional single-stage turbochargers have seen significant improvements in their low speed dynamic behaviour, even systems that are state-of-the-art struggle to satisfy these critical customer criteria.

Moreover, to further reduce CO₂ emissions, carmakers are not only downsizing engines, but also increasing the gearing to reduce the speed of the engine for even greater efficiency.  In this case, high load operating modes can extend well below 1,500rpm, and can even approach 1,000rpm, particularly when the driver suddenly demands a high level of torque from an idling engine.

CPT tests confirm that when applied to a radically downsized and down-speeded engine, its VTES technology dramatically increases the initial transient response, delivering significantly more torque at low engine speeds, thereby enhancing a car’s low speed drivability characteristics.   The combination of a highly dynamic electric supercharger, in series with a conventional fixed geometry turbocharger, also makes it relatively easy to optimise the overall response of the system, compared to other air charging methods.

The VTES system can also help reduce soot and particulate emissions from diesel engines, particularly when the driver accelerates at low engine revs, which, in turn, creates an opportunity to reduce the size and cost of the diesel particulate filter (DPF).  

“Fast response air-boost systems are essential for delivering radically-downsized engines,” says Morris.  “Even the most dynamically optimised turbocharger cannot deliver an air-side response approaching the fuel control capability of the latest injection systems.  The consequence is ‘air limited’ combustion, which imposes many compromises on the engine developer.

“Series boosting solutions are gaining popularity because of their extended low speed boosted air delivery capability, but their dynamic performance is still frustratingly linked to engine speed and air mass flow rates.  The provision of a cost-effective electric supercharger, in series with a conventional fixed geometry turbocharger, offers a combined transient effect, which as yet cannot be matched by other air charging systems.”

The VTES electric supercharger, which operates independently of engine speed, can significantly increase the air charge density over the critical first 10 combustion cycles of a low speed transient.  Fitted with a low inertia compressor, the supercharger accelerates from its 5,000rpm idle speed to a maximum speed of 70,000rpm in less than 0.35 seconds.  The system is highly dynamic and the intake charge boosting and resulting torque enhancement is achieved very typically in less than a quarter of a second (250ms).

Until recently the only intake charging solution with the potential to deliver comparable torque enhancement was a crankshaft driven mechanical supercharger, either operating on its own or combined with a conventional exhaust waste-gated turbocharger for better overall efficiency.  However, this approach has proved excessively complex for a number of engine developers.   The complexity results from the sophisticated requirements of the supercharger, turbocharger, clutch and air-bypass valves needed to deliver the response characteristics, and the demanding package and NVH (noise, vibration and harshness) requirements of the installation. 

CPT’s development of an electric supercharger with a near instantaneous air delivery system creates a viable cost-effective alternative.  With recent refinements to the bearing design and power electronics, it has been possible to almost halve the bill of material costs for the assembly of the supercharger, compared with earlier prototype designs.  Eight years of continuous product development has resulted in a mature well-proven cost-effective system.

Electric supercharging provides vital boost for low cost low carbon vehicles

One of the most cost effective steps that can be taken by vehicle manufacturers to reduce fuel consumption and CO₂ emissions is to fit an electric supercharger in combination with smaller petrol (gasoline) or diesel engines and taller gearing says Controlled Power Technologies. 

Following years of product development and the application of the very latest power electronics, the company’s innovative electric supercharger known as VTES or Variable Torque Enhancement System has been incorporated in a major project by engine developer AVL and will also feature in the Ricardo-led £3m ‘HyBoost’ programme announced by the Technology Strategy Board on 9 September 2009.  Both projects are seeking to maximise powertrain efficiency at the lowest possible cost.

The fully developed and production-ready device could prove timely in helping car makers meet EC directives to cut average CO₂ emissions from new cars to 130 grams per kilometre by 2012 and to 95 grams per kilometre by 2020.  There are heavy fines for non-compliance.  This means that by 2020 new cars will have to emit on average 40 per cent less CO₂ than they do today.   An electric supercharger could prove a key component for meeting these requirements.  It could also benefit novel internal combustion engine concepts currently in development, which often demand forced air induction. 

Unlike a crankshaft driven supercharger or exhaust driven turbocharger, which similarly boost the performance of a downsized engine, an electric supercharger operates independently of engine speed.   This crucial difference means the technology is perfectly suited to maintaining vehicle transient performance and driveability - now widely recognised as a critical marketing issue for any car maker contemplating radical downsizing of an IC engine to maximise fuel efficiency. 

“Motorists must feel confident that they can safely keep up with the flow of traffic and will have certain minimum expectations when it comes to vehicle performance,” says CPT engineering director Guy Morris. “This includes the need for an immediate torque response when stepping on the accelerator pedal.  As Lord Drayson, Minister for Science and Innovation, put it at the recent Low Carbon Vehicle conference ‘there’s little public appetite for poorly performing cars, whether they are environmentally friendly or not.  People want performance and efficiency’.  Electric supercharging also avoids the enormous expense and complexity of integrating an electric motor directly into a powertrain to create a mild or full hybrid electric vehicle.” 

Increasing the efficiency of the powertrain through extreme downsizing is fast becoming a widely-recognised near term solution for both petrol and diesel engines.  Unfortunately, downsizing the engine and increasing the gearing, while hugely beneficial for fuel economy and carbon emissions, tends to leave a massive torque deficit, particularly at low engine revs.  Finding cost-effective technology to overcome this issue is a universal problem facing engine developers.

CPT says electric supercharging offers performance and driveability as yet unmatched by other air charging methods.  Tests confirm that when applied to a radically downsized and down-speeded engine, the VTES system dramatically increases transient response, delivering significantly more torque thereby enhancing a car’s driveability at low engine speeds.  

For example, when applied to a radically downsized 1.2-litre turbocharged engine, VTES delivers in excess of a 50 per cent increase in torque at engine speeds below 3,000rpm, more than compensating for insufficient power from the exhaust turbine.  Significantly, more than 90 per cent of the available torque is delivered in less than a second.  Compared with a 1.6-litre naturally aspirated engine, the downsized engine with electric supercharger reduces the 70-100kph (44-63mph) top gear acceleration time from 18 to 11 seconds. 

“Even though engines equipped with a conventional mechanical supercharger or exhaust driven turbocharger have seen significant improvements in their dynamic behaviour at low engine speeds, they are fundamentally dependant on engine speed for their operation,” says CPT senior engineering manager Mark Criddle.  “Even state-of-the-art systems struggle to satisfy this critical customer requirement for driveability.  And while series boosting solutions are gaining popularity because of their extended low speed capability, their dynamic performance is still linked to engine speed and air mass flow rates.  The alternative method of boosting performance by integrating an electric motor between the engine and transmission to create a mild hybrid is a costly exercise and difficult to package in front wheel drive vehicles.”

CPT’s electric supercharger provides a viable low cost micro-hybrid solution, significantly increasing an engine’s air charge density over the critical first 10 combustion cycles of a low speed transient.  Fitted with a low inertia compressor, the supercharger accelerates from idle to its maximum speed of 70,000rpm in less than a third of a second enabling even a turbocharged engine to achieve full load torque within one second at very low engine speeds.  This fast dynamic response and rapid air boosting enables the system to react instantly to high transient load conditions, delivering up to 25kW (33bhp) of additional power at the crankshaft.  This is more than enough to compensate for any turbo lag and more cost effective than integrating a 25kW electric motor into the powertrain since only a 12-volt alternator and battery system is required. 

“Fast response air-boost systems are essential for delivering radically-downsized engines,” says Morris.  “Even the most dynamically optimised turbocharger cannot deliver an air-side response approaching the capability of the latest fuel injection technology.  The consequence is ‘air limited’ combustion, which imposes many compromises on the engine developer.”

The combination of a highly dynamic electric supercharger, which CPT recommends in series with a conventional exhaust driven turbocharger makes it relatively easy to optimise the overall response of the system, compared to other air charging methods.  The VTES technology can also help reduce soot and particulate emissions from diesel engines, particularly when the driver accelerates at low engine revs, which, in turn, creates an opportunity to reduce the size and cost of the diesel particulate filter (DPF).  

“Our electric supercharger is an ideal enabling technology for the extreme engine downsizing being advocated by European carmakers,” adds Criddle.  “The system has been designed to be sufficiently flexible to enable use of a common solution across a wide range of gasoline and diesel engine platforms.  It delivers the required economies of scale and complements the micro-hybrid strategy of using the existing 12-volt vehicle architecture as an economic alternative to higher voltage ISG based torque assistance.”

CPT’s electric supercharger has received a powerful boost (no pun intended) recently from two major projects, in which the adoption of this innovative technology has been recognised for the development of ultra-efficient low carbon vehicles.  It will feature in the Ricardo-led £3m ‘HyBoost’ project backed by the Technology Strategy Board as a part of the UK government’s investment programme to speed up the introduction of low carbon vehicles onto UK roads.  The electric supercharger also features in a major project by AVL, another leading independent engine developer, which has produced a demonstrator vehicle with the driveability of a significantly larger capacity gasoline engine, whilst meeting the industry’s holy grail of reducing CO₂ levels to that of an equivalent diesel powertrain.

Having demonstrated its electric boosting system at the Cenex Low Carbon Vehicle conference held at Millbrook on 9-10 September 2009, CPT is further showcasing the technology when it makes its annual pilgrimage to the international supercharging conference held in Dresden this week on 24-25 September 2009, where it will again meet with the world’s leading engine developers and industry experts following its technical presentation on VTES in 2008.  Meanwhile, CPT says it’s progressing a number of confidential development contracts that will lead to commercial applications, initially for small and medium volume production, and will continue to work with the industry’s powertrain developers to verify and validate the benefits of electric superchargers.

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