Innovations and Improvements in Single-Phase AC Motor Controls

Transcription

1 Innovations and Improvements in Single-Phase AC Motor Controls Howard Abramowitz AirCare Automation Inc. AirCare Automation Inc North Lamar Blvd. Suite B-11 Austin, Texas Toll free:

2 Single-Phase AC: Status Quo Perspective Advantages: Single-phase AC controls are inexpensive. Single-phase AC motors are also inexpensive. Perceived disadvantage: single-phase AC motors and controls have performance drawbacks compared to more expensive solutions. Feb Page 2 of 33

3 New Value Premise Drawbacks of single-phase AC can be compensated for Inexpensively! Infusing innovation improves traditional performance parameters and opens new control and function possibilities, increasing value. Result: Attractive re-positioning of single-phase AC performance and value relative to more expensive solutions. Feb Page 3 of 33

4 Areas of Innovation Energy Efficiency (3-wire & multiple loads) Operation (Soft-Start, expanded phase angle range) Network Control (Modbus RTU) & BMS Integration Technology (Pulse Control; Closed Loop Control ; Speed Sensing) User-Friendly HMI (PC-Based GUI) Feb Page 4 of 33

5 Normalized AC V & I Phase Control of AC Motor 1.2 Original AC Voltage AC INPUT (V) 0 Motor Voltage Chopped AC Voltage At Motor Resulting Motor Current Motor Current -1.2 Time Jan-14 Page 5 of 33

6 Unique 3-Wire Topology for Phase-Control Stage 1 Auxiliary & Primary chopped VariPhase TM AL ML AC Input N Stage 2 Primary only Speed Control AirCare 3-wire topology: reduces current rise in motor; reduces motor heating; reduces motor hum; reduces power consumption. Feb Page 6 of 33

7 Power (W) Current (A) AC Fan Performance 2-Wire vs. 3-Wire SAVE Ampere in current draw Power savings reflect lower amp draw Wire vs. 3-Wire Current vs RPM 115 Volt 60Hz Blower 2 20%-30% Amp increase typical 1.5 Idrive 2W 1 Idrive-3W Speed (rpm) 2-Wire vs. 3-Wire Motor Input Power vs RPM 115 Volt 60Hz Blower Psys-2W Psys-3W SAVE 40 Watts in Power draw Power Savings = system efficiency Savings reflect lower motor loss that results in cooler motor/extended life Speed (rpm) Total savings from optimized speed set can be 30-50% of full power draw!! Feb Page 7 of 33

8 Single-Phase AC Phase-Control Drives multiple motors with no degradation of power processing (no de-rating of drive to load)

9 Percent Harmonic Distortion AirCare 3-wire Topology reduces 3 rd Harmonic Harmonic order n < n < 39 Odd harmonics Maximum permissible harmonic current A 2, 30 1, 14 0, 77 0, 40 0, 33 0, 21 0, n Harmonics at Same RPM (1120) Fund 3rd 5th 7th 9th 11th Harmonic 2 Wire 3 Wire AirCare 3-wire design results in more efficient operation at a given rpm. This results in significantly lower 3 rd harmonics for the same operating point of the fan. Jan-14 Page 9 of 33

10 Fan Rotation Speed (RPM) Adding phase> 80% gives little increase in rpm 230 V, 60Hz, 1550 RPM AC Fan Motor Phase Angle Cut off (Degrees) RPM First 60 deg. provide zero speed and motor stalls Maximize functional linear control curve for optimal speed control Top 20% of curve truncated to eliminate the flat top performance First 30% of phase angle truncated to provide no-stall zone Feb Page 10 of 33

11 Max. Amps. SOFT-START Reduce Start-Up Currents by Half (or more) Soft-start saves significant installation costs and enhances long-term operating reliability. Max. Current vs Register 20 GE 115V 2.7A Without Soft-Start Register 20 With Soft-Start 2 Wire 3 Wire Soft-Start Register select Set-Up allows factory-set delay and rise time. Jan-14 Page 11 of 33

12 +5V Hall 0V 12V An2 0V An1 +5V Hall 0V 12V An2 0V An1 +5V Hall 0V 12V An2 0V An1 AC Phase-Control Units have MODBUS RTU interface to provide Network communications (serial bus) Set To Address 1 Set To Address 2 Set To Address 3 VARIPHASE FAN CONTROL - MODBUS INPUT: 115V 50/60HZ 8A OUTPUT: 115V 50/60HZ 8A VARIPHASE FAN CONTROL - MODBUS INPUT: 115V 50/60HZ 8A OUTPUT: 115V 50/60HZ 8A VARIPHASE FAN CONTROL - MODBUS INPUT: 115V 50/60HZ 8A OUTPUT: 115V 50/60HZ 8A STAT STAT STAT NET NET NET RJ45 Cables SELECT AirCare Console ADJUST ACC1 Console rea utoma tion.com Feb Page 12 of 33

13 AC Phase-Control Improvements 3-wire power management Multi-Load Management Improved speed linearity Improved Harmonic Distortion Soft Start Network Interface built-in Feb Page 13 of 33

14 Areas of Innovation Energy Efficiency (3-wire & multiple loads) Operation (Soft-Start, expanded phase angle range) Network Control (Modbus RTU) & BMS Integration Technology (Pulse Control; Closed Loop Control ; Speed Sensing) User-Friendly HMI (PC-Based GUI) Feb Page 14 of 33

15 Normalized AC V & I Pulse Control of TRIAC Skip a half-cycle Phase Control of AC Motor 1.2 Original AC Voltage AC INPUT (V) 0 Motor Voltage Chopped AC Voltage At Motor Resulting Motor Current Motor Current -1.2 Time Jan-14 Page 15 of 33

16 INTEGRAL CYCLE PULSE CONTROL 70% 2-Wire Leading-Cycle Surge 16

17 Integral Cycle Pulse Control Results 1. The integral-cycle thump noise is no less a nuisance than phasecontrol buzz. The result is no net mitigation of acoustic noise in the speed-controlled LE AC FFU. 2. Efficiency isn t significantly improved using ICM. 3. Increased peak currents resulting from ICM could lead to distortions of the AC mains, which in turn could cause a host of secondary issues in the surrounding electrical power environment. 4. Observed and researched elevated stress and damage to electrical and/or electro-mechanical components as a result of sub-harmonic effects creates significant unpredictability of success and liability risk. Feb Page 17 of 33 17

18 % or Full Speed (230V) Impact of Line Voltage on Variable Speed Motor EBM 230V Fan Line Voltage Sensitivity 110% 100% 90% 80% 70% 60% 50% 40% Console Settings 85% 90% 95% 100% 105% 110% 115% Open-loop RPM is very sensitive to AC Line Voltage variation: 70% set point on 1300 rpm results in 1000 rpm when line is 230V. AC line voltage variation of ±15% results in speeds ranging from rpm. 70% set pointover AC line results in wide rpm variation of 62% to 96% of full speed. Jan-14 Page 18 of 33

19 CLOSED LOOP CONTROL Flexible Feedback with PID loop AirCare VariPhase employs an adjustable PID algorithm to ensure stable and optimal control of fan speed based on feedback from a wide range of conventional sensors. Digital or Analog Input of Set Value VariPhase Speed Controller w/ PID Loop Control Feedback Signal Sensor feedback based on Temperature, Pressure, Humidity, Air flow, or RPM Works with any sensor that has 0-5 volt feedback signal Jan-14 Page 19 of 33

20 AC PSC Motor Phase-Control Sensor-less Options Back-EMF RPM Monitoring Input Voltage Monitor and Adjust Load Current Monitor and Adjust Feb Page 20 of 33

21 Primary Auxiliary Three Approaches to Sensor-less Regulated Phase-Control 1 Stage 1 Auxiliary & Primary chopped 1-Phase PSC Motor Monitor and Adjust for AC Line Variations AC Input Stage 2 Primary only Speed Control 3 Monitor and Adjust for Primary Back-EMF 2 Feb Page 21 of 33 Monitor and Adjust for Motor Current Variations

22 Auxiliary Primary Sensorless Speed Sensing via Back-EMF Monitoring motor voltage when power to the motor is temporarily removed provides accurate rpm determination with negligible impact on air-flow and fan torque. Feb Page 22 of 33

23 Back EMF, 90 Phase Angle Normal Back EMF increased Reverse conduction time increased Feb Page 23 of 33

24 Back-EMF Observations In addition to being affected by changes in motor loading due to air system conditions, motor current phase shift and back EMF also vary with: (dynamic) mains voltage (dimensional) phase angle (per assy) motor, motor model, impeller, filter medium (dynamic) degradation in motor performance, such as motor temperature variation, bearing wearout, etc. Feb Page 24 of 33

25 Two Module Block Diagram PowerCard Bias power Zero crossing TRIAC Drive Linearize speed Vsense auto adjust Isense motor alarm Status output (local) Min-speed (manual) Soft-start Options: 1 or 2 TRIAC, on/off switch SmartCard V,I monitoring Open/Closed Loop Control Auto-adjust for Line/Load change Analog (2 ) inputs Status output (remote) Min-speed software override MODBUS RTU network Addressing (DIP sw) Bias power by step-down xformer Feb Page 25 of 33 25

26 Bias Supply PowerCard SmartCard Speed Control Network Interface Card NIC Power Side Controller Linearize speed V,I,P sense Status output Current Current Sensing Speed PWM-to-Analog Manual Speed Vreg MinSpeed 26

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28 Air System vs Electrical System As air flow path obstructed: 1. air system impedance increases 2. air flow decreases 3. differential pressure increases across point of obstruction 4. differential pressure decreases across other static impedances in system Feb Page 28 of 33 Electrically: Watts decrease* Amps decrease* Current phase shift, & so Reverse Conduction Time, increase Back EMF increases Decreasing power for decreasing air flow Maximum power consumed at maximum air flow * Under-proportioned to changes in flow and pressure.

29 Closed Loop/Sensor-less Control Summary Monitored air-flow, pressure or other parameters provide direct control of a desired output of the fan Requires external sensor Requires stable PID control per application Provides accurate control of the desired output Monitor Voltage, current allow sensor-less (no sensor on the load.. it is all contained in the drive) control Requires isolated sensing on the motor control board Requires characterization of the application and algorithm in the Control to make changes per measurement Provides good RPM monitoring and control for lower cost/nosensor controls. Feb Page 29 of 33

30 Areas of Innovation Energy Efficiency (3-wire & multiple loads) Operation (Soft-Start, expanded phase angle range) Network Control (Modbus RTU) & BMS Integration Technology (Closed Loop Control ; built-in Speed Sensing) User-Friendly HMI (PC-Based GUI) Feb Page 30 of 33

31 ACC 9001 TECH TOOL Easy implementation of set-up & control Each ACC9001 (laptop PC) has the following software tools: AirCare Drive Configuration & PID Tuning Interface application AirCare Flash Downloader instant firmware updates for AirCare motor controllers AirCare product and reference documentation. join.me remote desktop application for live, on-screen factory assistance Flexible Modbus diagnostic tools: MODBUS RTU interface - includes AirCare factory connections screens scripts (MODSCAN 32). ComTest Pro Modbus device diagnostics and performance testing CAS Modbus Scanner detects/discovers Modbus slave devices on a network The ACC9001 has a cable integrity tester and digital multi-meter to assist in evaluating installations. Feb Page 31 of 33

32 ACC9001 GUI Provides Ease of use and Closed Loop Control tools Configure the Drive for desired parameters and change as needed (open loop/closed loop change on the fly) Adjust closed loop PID parameters and monitor resulting waveforms for rapid stable convergence

33 Single-Phase AC Controls Conclusions Phase-Control can provide cost-effective and improved performance to Single-Phase AC motor control for air-movement applications 3-wire improves efficiency Characterization and Digital Control provide control speeds Open loop control of AC Motor provides inherent limits to accuracy of output (i.e. rpm or air-flow) Accurate Control can be Added Through Low-Cost External Sensors or Innovative Sensor-less Approaches Air-Flow sensors, pressure sensors or others provide system performance levels that go beyond rpm control Monitoring the AC voltage, & AC current of the drive can help provide adjustments to open loop AC Single-Phase Motor Controls can provide low-cost and accurate monitoring/controls for low-speed/low-torque applications Feb Page 33 of 33

34 Innovations and Improvements in Single-Phase AC Motor Controls Howard Abramowitz AirCare Automation Inc. AirCare Automation Inc North Lamar Blvd. Suite B-11 Austin, Texas Toll free: