180 likes | 472 Vues
Outline. General Requirements, State of the Art, Structure and Components of Servo Drives Drive Control with Position/Speed Encoder Motion Control Drive Control without Position/Speed Encoder Data Exchange (Communication ). Typical Machine Tool. feed drives
E N D
Outline • General Requirements, State of the Art, Structure and Components of Servo Drives • Drive Control with Position/Speed Encoder • Motion Control • Drive Control without Position/Speed Encoder • Data Exchange (Communication)
Typical Machine Tool feed drives control the position between working piece and working tool main drives provide processing power
Parallel Kinematics TriCenter DMT 100 (Deckel Maho)
Characteristics of Servo Drives feed drives axis high efficiency small size smooth operation at low speeds 4 quadrant operation high maximum torque constant maximum torque speed range < 10.000 rpm rated power < 20 kW Spindle drives main high rated/continuous torque constant maximum power speed range < 20.000 rpm rated power < 100 kW
Hystory of Motor Types in Servo Drives ASM asynchronous motor ASM ? DC SM synchronous motor SM SM ? EC brushless DC 1970 ff. 1980 ff. 1990 ff.
State of the Art: AC Servos High Speed Spindle (Siemens) DSD Servo (Baumüller) High Torque Motor (Baumüller) Spindle Motor (Franz Kessler)
Encoders • Advantages • low cost • high accuracy • (e. g. by gear ratio) • Disadvantages • elastic effects • and back lash source : ERN-Geber, Heidenhain
Encoder Technologies Meßbereich measuring area Auflösung resolution Robustheit robustness Massenproduktion mass production robustness mass production measuring area resolution magnetisch magnetic Resolver: circular tooth wheel: point low (multipole resolver: 20 Bit) good bad magnetic optisch optical point high (CCD: > 30 Bit) problematic (sensitive to temperature and shock) very good (photographic production) optical kapazitive capacitive circular high good good Too less experience to make knowledge-based statements. capacitive technology
AC Servo Drive Control for synchronous machines speed controller current controllers field weakening field controller machine model for asynchronous machines
Motion Control (e. g. Electronic Gear) Synchronized communication Virtual master main drive
Sensorless Control Categories models based on anisotropies fundamental models emf-model, Observer dq-inductance rotor slotting effect main field saturation flux modulation ... ...
Industrial Drives with Sensorless Control since several years / decades sensorless control is investigated and published on conferences and magazines - acceptance in industry, however, is rather low Why ? new ideas and concepts are interesting for industry, only if they do not result in higher cost or higher effort!!! What does that mean for industrial drives with sensorless control ? no additional or more powerful processors / controllers no additional hardware or additional sensors (e. g. voltage sensors) no increased installation effort with respect to parameter adjustments
SERCOS interface MDT AT MST AT AT AT MST M m 1 2 t 1.1 t 1.2 t 1.m t 1.M t 2 t Scyc • t1.x AT transmission starting time • t2 MDT transmission starting time • tScyc SERCOS cycle time
Future Developments Motors (Actors) • synchronous motors with surface mounted permanent magnets as a standard - different solutions in special applications only (for cost reasons) Signal Processing • further developments on speed/position encoders to be expected • sensorless/encoderless control only, if no additional hardware effort (processors and/or sensors) no parameter dependencies during operation Data Exchange/Communication • synchronized communication systems are demanded for multi axis servo drive systems for high requirements