Technologies for Energy Efficient Electric Motors Sebastio Lauro
Technologies for Energy. Efficient Electric Motors Sebastião Lauro Nau, Dr. Eng. – slnau@weg. net Research and Technological Innovation Department - WEG Motores Rua Venâncio da Silva Porto, 399 - Malote 41 89252 -230 - Jaraguá do Sul - SC, Brasil I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
Summary § Introduction § Switched Reluctance Motors § Synchronous Reluctance Motors § Permanent Magnet Motors § Examples of Industrial Energy-Efficient Motors § Examples of Energy-Efficient PM Motors for Special Applications § Conclusions I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
Introduction § Induction motors: § widely used due to simplicity, robustness, reliability, direct-on-line operation. § Variable-speed drives: § energy savings in fluid-flow applications, elimination of gear boxes in low-speed high-torque applications, wide-speed range in variable-speed applications. § induction motors with scalar or field-oriented control. § brushless ac pm motors and synchronous reluctance motors with fieldoriented control (or scalar control for small motors using Hall sensors). § brushless dc pm motors and switched reluctance motors with electronic commutator. § Comparisons are always difficult, depend on application requirements (speed range, maximum speed, efficiency, noise). I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
Reluctance Motors I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
Switched Reluctance Motors § No magnets, no squirrel cage § No Joule losses in the rotor § Independent pole windings (no electrical connection between phases) § Same power/frame ratio as induction motors § Higher vibration and acoustic noise § Require sophisticated electronic controller (current control to reduce vibration and noise problems) § Applications: where wide speed range and high speed are necessary like pumps, household appliances, electric vehicles, etc. I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
Synchronous Reluctance Motors § No magnets, no squirrel cage § No Joule losses in the rotor § Similar stator as induction motors § Same power/frame ratio as induction motors § Require electronic controller (fieldoriented control) § Higher current, lower power factor §Applications: pumps, elevators, compressors, conveyor belts, extruders, etc. I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
Permanent Magnet Motors I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
Characteristics § The most efficient of all motors § High torque-to-current and torque-to-volume ratios § High power factor § Require electronic controller § Use Rare-earth or Ferrite magnets § BLAC or BLDC type with several rotor configurations § Applications: pumps, elevators, compressors, blowers, conveyor belts, extruders, generators, electric vehicles, servodrives, household appliances, etc. I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
BLAC and BLDC Motors § PM BLAC (brushless ac) Motors or PMSM (permanent magnet synchronous motors): § Similar windings as for induction motors § AC-sinewave drive with field-oriented control § Low torque ripple and acoustic noise § PM BLDC (brushless dc) Motors: Distributed windings § Usually have concentrated windings § DC-squarewave drive for phase commutation § Generally used in low-power applications Concentrated windings I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
Surface-Magnet Motors § BLAC or BLDC motors § Distributed or concentrated windings § Rare-earth or Ferrite magnets § Easier rotor manufacturing Distributed windings § Poor field-weakening capability (low inductance) § Usually no reluctance torque § Concern about retention of magnets against centrifugal forces in high-speed operation Concentrated windings I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
Interior-Magnet Motors § BLAC or BLDC motors § Mostly distributed windings § Rare-earth or Ferrite magnets § Improved field-weakening capability § Higher leakage flux § Reluctance torque § More difficult rotor manufacturing than surface PM motor V-shape magnets Tangential magnets Multi-layer magnets Radial magnets I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
Exterior-Rotor PM Motors § BLAC or BLDC motors § Mostly concentrated windings § Mostly Ferrite magnets § Surface-magnet rotor § Higher torque-to-volume ratio than interior-rotor motors 8 -pole pm motor § No reluctance torque § Easier rotor manufacturing § No concern about retention of magnets against centrifugal forces in high-speed operation 16 -pole pm motor I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
Electronically Commutated (EC) Motors § BLAC or BLDC motors § Higher efficiency than PSC and shaded-pole motors § Mostly concentrated windings § Mostly Ferrite magnets § Surface-magnet rotor § Low-power applications (residential and commercial applications) § No reluctance torque § Easier rotor manufacturing § Very low-power motors can have the electronic controller integrated within the motor enclosure I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
Line-Start PM Motors § Hybrid induction/pm motors § Similar windings as for induction motors § Rotor cage for asynchronous starting § Permanent magnets beneath the cage for synchronous (steady-state) operation § Rare-earth magnets § More difficult rotor manufacturing than surface PM motor § Do not need electronic controller for DOL operation § Limited to low-inertia applications, due to synchronization capability I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
Rare-earth PM challenge § Since early 2011, prices of Nd. Fe. B PMs have been increasing considerably, due to China’s limited quotas and raised taxes on rare-earths exports. § Increasing price of rare-earth magnets poses a possibility of magnet manufacturing in other countries, including Brazil. § Prices of Rare-earth magnets are not stabilized yet. § Search for efficient but non-rare-earth motor technologies Samarium Neodymium Source: http: //www. metal-pages. com I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
Magnets Consumption at WEG 2010: Ferrite: 1175 kg Nd. Fe. B: 2366 kg 2011: Ferrite: 997 kg Nd. Fe. B: 2863 kg Nd. Fe. B Price Increase (average): Sep 11/Jan 11: 300% Nov 11/Jan 11: 250% I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
Examples of Industrial Energy-Efficient Motors I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
IPM Motor With High-Energy PM (Rare-earth) § Wmagnet Drive System: since 2009 § Same inverter as for induction motor – CFW-11 (sensorless control) § Output: 11 k. W – 150 k. W § Base speed: 1500 and 3000 rpm § Frames: 132 S – 250 S/M § High-energy rare-earth magnets in the rotor Super Premium Efficiency § Higher torque/volume ratio (one frame size smaller than induction motor) § Extended life time § Applications: pumps, elevators, compressors, conveyor belts, extruders, centrifuges, etc. I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
Line-Start PM Motor With High-Energy PM (Rare-earth) § WQuatro: since 2010 § For DOL starting § Output: 0. 37 k. W – 7. 5 k. W § 4 and 6 poles § Frames: 80 – 132 M/L § Specially designed aluminum cage § High-energy rare-earth magnets beneath the cage Super Premium Efficiency § Same power/frame as for induction motor § Applications: low-inertia loads I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
Examples of Energy-Efficient PM Motors for Special Applications HVAC applications Washing machines Cooling towers Electric vehicles I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
High-Eff. PM Motors for HVAC Applications § Example: EC motor for ventilation application § Surface ferrite magnets § Integrated drive, 115 or 230 V, 60 Hz input § Nema 48 frame, 1/4 to 1 HP § 200 – 1750 rpm § 80% total efficiency I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
High-Eff. PM Motors for Washing Machine § PM motor front-load washing machine § External rotor, surface ferrite magnets § Power at agitation: 60 W § Efficiency at agitation speed (400 rpm): 66% § Efficiency at spin (850 rpm): 86% § High torque @ low speeds I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
High-Eff. PM Motors for Washing Machine § PM motor for top-load washing machine § Radial ferrite magnets § Rated power: 1/3 HP § Efficiency at agitation cycle: 66% § Efficiency at spin cycle: 86% § High speed § Low torque I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
High-Eff. PM Motors for Cooling Tower § High-energy PM magnets § Direct-drive: eliminates gear-boxes less maintenance and less mechanical losses § High-torque, low-speed motor § Drive with sensorless control § Power: 15 k. W – 150 k. W § Torques: 500 – 10000 NM § Speeds: 100 – 300 rpm § Frames: 355 – 450 (special frames with shorter axial dimension) § Extended life time Example of a 45 k. W, 200 rpm, 2150 Nm cooling tower motor. Efficiency: 94. 3% I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
High-Eff. PM Motors for Electric Vehicles § High-energy PM magnets § Rated Power: 21 k. W § Base speed: 3600 rpm § Maximum speed: 10000 rpm § Water cooled § Drive input voltage: 220 V I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
Conclusions I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
Comparison of Several Motor Technologies Reference: induction motor Symbols: ---= much lower slightly lower similar to induction motor + ++ +++ slightly higher much higher I Seminário Brasileiro de Terras Raras - 07/12/2011 - Rio de Janeiro
- Slides: 27