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Elevator Drives - Discussion

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1 Elevator Drives - Discussion
History Requirements Motor and Control Types Industry Trends Future Drives 1

2 History 236 BC – First Passenger Lift, Archimedes
1853 – Safe Elevator Demo, Elisha Otis 1857 – First Safe Elevator Installation, Cooper Union, NYC 1861 – Otis Elevator Patent 2

3 Otis Patent 1861 3

4 History 1873 – First Modern DC Motor
1874 – J. W. Meaker Door Opener Patent 1880 – First Electric Motor Controlled Elevator Siemens / Sprague – Tesla AC Induction Motor Phase Squirrel Cage Design 1889 – Otis Elevator Uses DC Motor 4

5 Otis DC Elevator Motor Circa 1889

6 History 1891 – Ward Leonard Variable Speed Control
AC Induction Motor Turning DC Dynamo Rheostat to Control Generated Voltage DC Voltage Controls DC Motor Speed ’s – Ward-Leonard M-G Sets and DC Motors Used for Variable Speed Elevators AC Motors Used 1 and 2 Speed Starters 6

7 Otis No. 1 Geared DC Machine with DC Motor
Circa 1915 7

8 Otis Gearless DC Machine
Circa 1919 8

9 M-G Set Controls (Otis Elevator, 1920’s)

10 Otis Type 84 26 Broadway,NYC Circa 1930’s

11 History 1975-Present 1980’s – Microprocessors Improve
Thyristor (SCR) DC Drives Control Elevators All Analog Components in the 70’s Replaces Aging M-G Sets 1980’s – Microprocessors Improve Car Dispatch and Motor Drive Controllers 11

12 Otis type 84,NYC with Encoder

13 Westinghouse #205 with Encoder

14 History Late 1980’s – Early 1990’s – Mid-1990’s –
Variable Frequency Inverters AC Induction Motors, Geared Applications Only Early 1990’s – More AC Inverters and Motors Begin to Displace Small DC, 3-15 HP Mid-1990’s – Vector Control AC Inverters HP Almost as Good as SCR-DC. KONE Introduces PM EcoDisc AC Machine 14

15 History Late 1990’s – Custom Gearless AC Induction Machines
First Fully Regenerative AC Elevator Drives Much Discussion on PM-AC and MRL SCR-DC Still Used for Medium and Large Building Mods 15

16 History 2000-Present – More PM-AC Motor Manufacturers. PM Gearless Begins to Replace AC Geared EU Focus on Efficiency and Harmonics/EMC Lower Cost IGBT Inverter Components North America Begins to Focus on Energy Reduction New Construction Leaning toward AC SCR-DC Still Used on Medium-Large Building Mods 16

17 Four Quadrant Operation

18 Linear power stage R M Umot, Imot LSC Vcc time advantages
simple, low priced controller low electromagnetic noise level no minimum inductance needed disadvantages high power losses at the final stage at high currents or low motor voltages (PV = R I2) for small nominal power up to 100 W controller R UT M Umot Gnd

19 Pulsed power stage (PWM)
advantages low power losses high efficiency for higher nominal power disadvantages electromagnetic noise in the radio frequency range high power losses in the motor at standstill minimum inductance necessary Vcc power stage pulse generator M Umot Gnd ADS, DEC, AECS, DES, MIP, PCU, EPOS Umot, Imot time cycle time: ms

20 Pulsed power stage: current ripple
general measures: reduce motor voltage enhance total inductance motor choke in controller additional motor choke enhance PWM frequency low motor inductance 50% 50% additional motor choke Umot, Imot 30% 70%

21 Time scales in control loops
frequency kHz mechanical time constants "slow" position controller position controller MIP speed controller current controller speed controller as "link" between fast current controller and a slow position control (PLC) PWM cycle time ms cycle time

22 Figure : PWM Control Signal
PWM(Pulse Width Modulation Cambiando il duty cycle, la velocità cambierà Lo scopo è : 1. Ridurre la dissipazione di potenza. 2. Ridurre I problemi di raffreddamento dei transistors) Figure : PWM Control Signal

23 Duty cycle si definisce duty cycle d il rapporto tra la durata del segnale "alto" ed il periodo totaleT del segnale, e serve ad esprimere per quanta porzione di periodo il segnale è a livello alto:

24 PWM Un segnale PWM (Pulse Width Modulation ovvero modulazione a variazione della larghezza d'impulso) è un' onda quadra di duty cycle variabile che permette di controllare l'assorbimento (la potenza assorbita) di un carico elettrico(nel nostro caso il motore DC), variando modulando) il duty cycle.

25 Un segnale PWM è caratterizzato dalla frequenza (fissa) e dal duty cycle (variabile);
si deduce dalla Figura, il duty cycle è il rapporto tra il tempo in cui l'onda assume valore alto e il periodo T (l'inverso della frequenza: T=1/f) Es. un duty cycle dell'80% corrisponde ad un'onda quadra che assume valore alto per l'80% del tempo e basso per il restante 20%,

26 DC Motor Drives DC motor speed control using Switching Control or PWM

27 Power Electronic converter
H-bridge converters circuit




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