EE130 Electromechanics 2013 J. Arthur Wagner, Ph.D. Prof. Emeritus in EE
Flow Control Throttling vs. Adjustable Speed Drive (ASD)
Fig. 1.2 a Tradional flow control system
Fig. 1.2 b Adjustable speed drive (ASD)-based flow control system Control pump speed to match flow requirement
Electric-motor drive Adjustable speed drive (ASD) Power Processing Unit (PPU) Electric motor drive, motor drive, drive –PPU –Sensor –Controller –(Motor)
Fig. 1.3 Block diagram of an electric drive system
Adjustable Speed Drive (ASD) Hardware from a home air conditioner (about two large rooms) Smooth torque pump AC input Full wave rectifier Smart (Intelligent) Power Module (removed) Three wires to motor Capacitors Sensor
Growth of Electric Drives Fast, cheap DSPs Efficient and controllable semiconductor switches –Increased switching speeds –Increased voltage –Increased current
List Motors in your everyday experience Motor application Type ? Drive ?
Fig. 1.4 Power and speed range of electric drives
Save Energy in Pumps Constant speed drive ASD
0 Flow Rate (Q) Pressure (H) Throttled System Curve Unthrottled System Curve Pump curve at full speed Pump curve at reduced speed A B C D ( H 2 + H, Q 2 ) ( H 2, Q 2 ) ( H 1, Q 1 ) Q1Q1 Q 2 Pressure across throttling valve, Fig. 1.6 Typical pump and system curves A Full speed pump B Unthrottled System C Throttled System D Reduced speed pump Main point: eliminate the pressure drop across the throttling valve
Fig. 1.7 Power consumption in a blower
Electric Drives Significant in Wind Energy Wind energy probably “better” than photovoltaic (PV). Advantage? DC power grid AC to DC then DC to AC Making High Voltage DC more attractive for off-shore systems
Fig. 1.8 Electric Drive for Wind generators
Read Problem 1-5 Cp Blade pitch angle Cut-in wind speed = Wind speed, above which, useful power is generated. Main point: For optimization we want to vary the shaft speed; an ASD allows us to do this.
Coefficient of Performance Cp = Pshaft/Pwind
Solution 1-5
Homework Chapter 1, Due next Tuesday Problems 1.1 and 1.5