All-Mechanical Flywheel Battery Technology for Electric Vehicle Surge-Power

TSI is a company that enjoys a unique world-wide position as a full-service flywheel battery and ceramic bearing supplier, including the design and application engineering of cost-competitive products.  The following article describes one of their recent product developments.

TSI has developed a line of patented all-mechanical flywheel batteries of a simple zero-maintenance twenty-year-life design that can be manufactured at lower cost than any competitive product with much lower life-cycle cost, with immunity to temperature extremes and with zero ecological impact, compared to chemical batteries.  The first TSI production-size unit was delivered under Bellcore purchase order and is now being tested there.  Also, TSI participated with its regional Bell Telephone Operating Companies on the Generic Requirements for back-up telecommunications power units to be purchased for beta-sites in the next few months and for wide-spread deployment next year.

A flywheel battery for electric vehicle surge-power has been available for demonstration in the TSI lab for three years, and a range of sizes of prototype products have been designed for other applications in non-interruptable power, power conditioning and alternative energy.  The basic TSI-patented flywheel-battery design consists of only a half-dozen all-mechanical components, only slightly modified standard motor/generators and simple advanced- technology digital controllers, for providing efficient flywheel back-up power over long maintenance-free life at minimum manufacturing cost.

A strategic alliance has been arranged with a major international carbon fiber composite flywheel rim manufacturer and another is now being arranged with a major motor/generator manufacturer to help market and manufacture the TSI flywheel products.  TSI now possesses a one-of-a-kind centerpiece precision bearing ball lapping machine and know-how to manufacture the ceramic balls needed for its patented ultra-low-friction-loss small flywheel batteries at a production rate required for 40,000 units in one machine load.  The TSI production cost of these ceramic balls is a small fraction of the current market price, and enough can be manufactured at TSI for the seven figure near-term annual production of flywheel batteries predicted.  Arrangements are being made with other local manufacturing facilities to make the remaining few parts needed to supply the above large emerging flywheel battery markets at low cost, drawing on the huge local reserve of automated bearing, steel and other high-volume mechanical component production technologies.

Background

TSI is a recognized leader in integrated flywheel battery systems, flywheel safety containment design and solid-lubricated bearing technology.  Its patented technology covers a wide range of flywheel battery sizes, manages the benign dissipation of the kinetic energy of flywheels on their contacting surfaces in accidents, and controls the motion and lubrication of rolling elements in bearings.  TSI's products extend the operating regime of flywheel batteries and bearings to higher speeds, extreme temperature ranges, longer life, and zero maintenance in a wide variety of industries, using the latest findings in tribology, the study of friction, lubrication and wear.

TSI possesses a commercially viable demonstration Flywheel Energy Storage System (FESS) operating with negligible vibration over its design speed range in TSI's lab.  Although tens of millions of dollars are being spent on flywheel development, TSI is the only player to solve all of the significant problems of friction, vibration and systems integration with a basically simple very-low- cost design using patented technologies.

Current commercial flywheel batteries use expensive active magnetic bearings, since standard bearings need periodic lubrication, usually with volatile petroleum-based oils and greases.  The bearings for FESS's must operate unattended continuously for many years in a vacuum to eliminate windage losses.  TSI has solved this problem with a breakthrough in the technology, demonstrating reliable self-contained solid-lubricated hybrid-ceramic bearings based on new advanced lubricant and bearing materials, advanced bearing design theory, and dynamic computer analysis.

With TSI's know-how and protected technology, new flywheel battery and bearing products that minimize wear and maintenance, and optimize lubrication, life and reliability, have been designed, manufactured and proven in a wide variety of industrial and aerospace applications.  These include advanced-technology bearings for high-speed motors, gas turbines, diesel engines and other automotive applications, and flywheels for hybrid-electric vehicles and telecommunications back-up power.

FESS's are an approach for storing energy mechanically as the rotational kinetic energy in a flywheel rotor, instead of chemically as in conventional batteries.  Traditional problems of friction and high speeds, as well as customer concerns over safety containment of potentially harmful fragments in accidents, have plagued the use of flywheels in modern day applications.

These challenges have been solved by TSI, which in early 1995 produced a commercially viable FESS, including a novel, effective containment system.  The prototype demonstration unit, which is designed for surge power applications in an electric vehicle (500 Wh of energy storage and 40 kW of power), consists of only a few component parts that can be manufactured in production at an order of magnitude lower cost than the current selling price of competitive flywheel batteries.  The unit incorporates proprietary technologies that have been developed by TSI and other TSI licensees, who are leaders in the component fields.

This prototype unit has run very smoothly and repeatedly up to its maximum design speed of 28,000 rpm (and up to 50,000 rpm more recently on the smaller Bellcore prototype), during which the vibration is limited by its patent-pending, completely mechanical, basically simple, vibration isolator to only a few tenths of a G amplitude over the entire speed range.  This prototype with its TSI patented hybrid-ceramic ball bearings and patent-pending containment system was shown at the American Tour de Sol in Washington in May 1996.  The containment system is based on a successful rotor-burst test and thorough analysis and is currently being proof tested under government contract in several additional intentional rotor burst tests.  Patent applications are pending that cover all of TSI's flywheel battery component and integrated technologies, in addition to its extensive world-wide patents on advanced bearing and flywheel containment technologies.

The success of TSI's prototype flywheel batteries at Bellcore and in its lab has positioned its flywheel technology for immediate commercialization in on-line UPS's and surge power applications.  TSI has developed design modifications with projected ultra-low system losses based on vacuum belljar spin-down bearing friction tests demonstrating 0.00001 coefficient of friction.  These designs are required to extend the market to include stationary utility applications, where the idling efficiency is more of a requirement.