kinetic energy recovery system (all types of KERS )

Student at P K Technical Campus - India um P K Technical Campus - India
31. Aug 2016

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kinetic energy recovery system (all types of KERS )

  3. KERS EXPLAINED  KERS is a collection of parts which takes some of the kinetic energy of a vehicle under deceleration, stores this energy and then releases this stored energy back into the drive train of the vehicle, providing a power boost to that vehicle.  For the driver, it is like having two power sources at his disposal, one of the power sources is the engine while the other is the stored kinetic energy.
  4. WHAT IS KERS?  The acronym KERS stands for Kinetic Energy Recovery System.  Kinetic energy recovery systems (KERS) store energy when the vehicle is braking and return it when accelerating.  During braking, energy is wasted because kinetic energy is mostly converted into heat energy or sometimes sound energy that is dissipated into the environment.  Vehicles with KERS are able to harness some of this kinetic energy and in doing so will assist in braking.  By a touch of a button, this stored energy is converted back into kinetic energy giving the vehicle extra boost of power.
  5. BASIC ELEMENTS OF KERS  First, a way to store and then return energy to the power train and  Second, a place to store this energy. In essence a KERS systems is simple, you need a component for generating the power, one for storing it and another to control it all. Thus KERS systems have three main components: The MGU, the PCU and the batteries/flywheel.
  6. MGU (MOTOR/GENERATOR UNIT)  While a motor-generator set may consist of distinct motor and generator machines coupled together, a single unit motor- generator will have both rotor coils of the motor and the generator wound around a single rotor, and both coils share the same outer field coils or magnets Working in two modes, the MGU both creates the power for the batteries when the car is braking, then return the power from the batteries to add power directly to the engine, when the KERS button is deployed.
  7. PCU (Power Control Unit)  It serves two purposes, firstly to invert & control the switching of current from the batteries to the MGU and secondly to monitor the status of the individual cells with the battery. Managing the battery is critical as the efficiency of a pack of Li- ion cells will drop if one cell starts to fail. A failing cell can overheat rapidly and cause safety issues. As with all KERS components the PCU needs cooling.
  8. WORKING PRINCIPLE  Basically, it’s working principle involves storing the energy involved with deceleration and using it for acceleration. That is, when a car breaks, it dissipates a lot of kinetic energy as heat. The KERS tries to store this energy and converts this into power, that can be used to boost acceleration.  A standard KERS operates by a ‘charge cycle and a ‘boost cycle’. As the car slows for a corner, an actuator unit captures the waste kinetic energy from the rear brakes. This collected kinetic energy is then passed to a Central Processing Unit (CPU) and onto the storage unit. The storage unit are positioned centrally to minimize the impact on the balance of the car.
  9. TYPES OF KERS  There are two basic types of KERS systems:  Electrical  Mechanical  The main difference between them is in the way they convert the energy and how that energy is stored within the vehicle.
  10. ELECTRICAL KERS  In electrical KERS, braking rotational force is captured by an electric motor / generator unit (MGU) mounted to the engines crankshaft.  This MGU takes the electrical energy that it converts from kinetic energy and stores it in batteries. The boost button then summons the electrical energy in the batteries to power the MGU.  The most difficult part in designing electrical KERS is how to store the electrical energy. Most racing systems use a lithium battery, which is essentially a large mobile phone battery.
  11.  Batteries become hot when charging them so many of the KERS cars have more cooling ducts since charging will occur multiple times throughout a race.  Super-capacitors can also be used to store electrical energy instead of batteries; they run cooler and are debatably more efficient.
  13. MECHANICAL KERS  The concept of transferring the vehicle’s kinetic energy using flywheel energy storage was postulated by physicist Richard Feynman in the 1950.  The mechanical KERS system has a flywheel as the energy storage device and it does away with MGUs by replacing them with a transmission to control and transfer the energy to and from the driveline.  The kinetic energy of the vehicle ends up as kinetic energy of a rotating flywheel through the use of shafts and gears.  Unlike electrical KERS, this method of storage prevents the need to transform energy from one type to another. Each energy conversion in electrical KERS brings its own losses and the overall efficiency is poor compared to mechanical storage.  To cope with the continuous change in speed ratio between the flywheel and road-wheels, a continuously variable transmission (CVT) is used, which is managed by an electro-hydraulic control system. A clutch allows disengagement of the device when not in use.
  14. MECHANICAL KERS  Braking at the wheels dissipates the kinetic energy of the vehicle that is therefore completely lost. Conversely, KERS may store the kinetic energy of the vehicle during braking and return it under acceleration.  The system utilizes a flywheel as the energy storage device and a Continuously Variable Transmission (CVT) to transfer energy to and from the driveline to the rotating flywheel.  The transfer of the vehicle kinetic energy to the flywheel kinetic energy reduces the speed of the vehicle and increases the speed of the flywheel. The transfer of the flywheel kinetic energy to the vehicle kinetic energy reduces the speed of the flywheel and increases the speed of the vehicle.  The CVT is used because the ratios of vehicle and flywheel speed are different during a braking or an acceleration event. can change sleeplessly through an infinite number of effective gear ratios between maximum and minimum values. This contrasts with other mechanical transmissions that offer a fixed number of gear ratios.
  16. ADVANTANGE OF MECHANICAL KERS OVER ELECTRICAL KERS  Battery-based electric hybrid systems require a number of energy conversions each with corresponding efficiency losses. On reapplication of the energy to the driveline, the global energy conversion efficiency is 31–34%. The mechanical hybrid system storing energy mechanically in a rotating fly wheel eliminates the various energy conversions and provides a global energy conversion efficiency exceeding 70%, more than twice the efficiency of an electric system.
  17. ADVANTAGES OF KERS This potential advantages and features of this technology in the field of automobiles are:  High power capability  Light weight and small size  Long system life of upto 250,000 kms  Completely safe  A truly green solution  High efficiency storage and recovery  Low embedded carbon content
  18. CURRENT APPLICATIONS OF KERS  A consortium led by a Jaguar Land Rover is developing a flywheel-hybrid system that it says boosts performance by 60 kilowatts (about 80 horsepower) while improving fuel efficiency 20 percent. Jaguar is testing its purely mechanical flywheel system, which reportedly weighs 143 pounds, in an prototype XF sedan.  At the 2011North American International Auto Show Porsche unveiled a RSR variant of their Porsche 918 concept car which uses a flywheel-based KERS system that sits beside the driver in the passenger compartment and boosts the dual electric motors driving the front wheels and the 565 BHP V8 gasoline engine driving the rear to a combined power output of 767 BHP.
  19. CONCLUSION  It’s a technology for the present and the future because it’s environment-friendly, reduces emissions, has a low production cost, increases efficiency and is highly customizable and modifiable. Adoption of a KERS may permit regenerative braking and engine downsizing as a means of improving efficiency and hence reducing fuel consumption and CO2 emissions.  The KERS have major areas of development in power density, life, simplicity, effectiveness and first and foremost the costs of the device. Applications are being considered for small, mass-production passenger cars, as well as luxury cars, buses and trucks.
  20. REFERENCE  Sreevalsan S Menon, “Design And Analysis Of Kinetic Energy Recovery System In Bicycles”, Vol. 2, Issue 8, August 2013, International Journal of Innovative Research in Science, Engineering and Technology ISSN: 2319-8753 [1] pp 1029  Kevin Ludlum, “Optimizing Flywheel Design for use as a Kinetic Energy Recovery System for a Bicycle”, 3/6/13 [2] pp 1029  Alberto. Boretti, “A fun-to-drive, economic and environmental friendly mobility solution”, Journal of power technologies 93 (4) -2013 pp 1030  Mugunthan, U. Nijanthan, “Design & Fabrication of Mechanism for Recovery of Kinetic Energy in Bicycle Using Flywheel”, ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 5, Issue 5, May 2015, International Journal of Emerging Technology and Advanced Engineering pp 1029