Innovations in PWM Drive Technology for Nanometer Level Motion Control Applications May 14, 2014 Jason Goerges
ACS Motion Control Company Introduction 1985: Company Founded in Israel 2000: North American Technical Support and Sales Center Established 2002: First SPiiPlus Motion Controller Products Released 2010: First SPiiPlusNT EtherCAT Based Motion Controller Products Released ACS: A Provider of World Class Motion Control Solutions Motion Controllers Motor Drives Auxiliary Motion Control Products Advanced Real Time Control Algorithms Software Simulation, Development and Analysis Tools 2 2014 ACS Motion Control Ltd
Applications with Nanometer Level Motion Control Requirements Semiconductor Wafer Inspection OLED and FPD Inspection Linear Air Bearing Stages Lens Grinding Equipment Laser Beam Alignment Coordinate Measuring Machines (CMM) Scanning Electron Microscopes MEMS testing/nanoprobing 3 2014 ACS Motion Control Ltd
Example Application Needs - Wafer Inspection Current generation - 300mm XYZ or XX YZ linear motor precision positioning stage with air or precision cross-roller bearings Standstill following error (jitter) 1-10 Nanometers Very demanding constant velocity, ± 10 to 20nm following error @ < 1mm/sec Next generation - 450 mm XX YZ precision stage with larger footprint and inertia, more difficult to control Standstill jitter < 1 Nanometer More demanding constant velocity, ±10nm following error @ > 1mm/sec Higher voltage and current requirements for motors and drives 4 2014 ACS Motion Control Ltd
Linear Motor Drive Basics Drive acts as variable resistor, adjusting based on needs of load (motor) When speed is low and required torque is high, voltage drop on drive is high, resulting in large heat dissipation 5 2014 ACS Motion Control Ltd
Linear Motor Drive Summary Advantages Low electrical noise High electrical bandwidth Zero crossover distortion (ideal linearity) Zero current ripple Disadvantages Low efficiency, significant heat generation, low power to volume ratio Difficult / expensive fault protection Complex supply requirements (multiple logic and drive supply inputs) Analog current control (difficult to change/optimize)\ Relatively few vendors Limited Power Range Relatively expensive These disadvantages make linear drives suitable mostly for select niche applications, including nanometer level positioning applications 6 2014 ACS Motion Control Ltd
PWM Motor Drive Basics Drive acts as high frequency on/off switch, average current is linearly related to on/off ratio (duty cycle) At any instant, switch is open (no current flowing) or closed (no voltage across switch), resulting in very low heat dissipation. 7 2014 ACS Motion Control Ltd
PWM Motor Drive Summary Advantages High efficiency, low heat dissipation, high power to volume ratio Excellent fault protection Simple supply requirements Relatively cost effective Wide Power Range Disadvantages High switching noise Cross over distortion (non-linearity) Current ripple These disadvantages make PWM drives unsuitable for most nanometer level positioning applications! 8 2014 ACS Motion Control Ltd
NanoPWM TM A Revolutionary Innovation in High Precision Motor Drive Technology NanoPWM TM : A line of unique PWM drives based on ACS proprietary PWMBoost TM technology, developed over the last 5 years to address the needs of nanometer level positioning applications. 9 2014 ACS Motion Control Ltd
NanoPWM TM Drive Summary Advantages Combining the Best of PWM and Linear Drives Low electrical noise High electrical bandwidth Zero crossover distortion Low current ripple High efficiency Simple supply requirements Large power range Digital current loop control Compact Cost effective Currently available in MC4U platform (19 chassis with integrated motion controller, power supply, and motor drives), expansion to standalone drive platforms coming 10 2014 ACS Motion Control Ltd
NanoPWM TM Performance Examples Nanometer stepping profile Linear ironless servomotor stage with 0.4um pitch SinCos encoder, cross roller bearings 11 2014 ACS Motion Control Ltd
NanoPWM TM Performance Examples Standstill following error jitter comparison Standard PWM NanoPWM 12 2014 ACS Motion Control Ltd
NanoPWM TM Performance Examples Standstill following error jitter comparison Linear NanoPWM 13 2014 ACS Motion Control Ltd
NanoPWM TM Performance Examples Low speed (1mm/sec) following error comparison Linear NanoPWM 14 2014 ACS Motion Control Ltd
NanoPWM TM Performance Examples Wafer inspection XX Y gantry, standstill jitter performance X axis Y axis 15 2014 ACS Motion Control Ltd
NanoPWM TM Performance Examples Wafer inspection XX Y gantry, move and settle performance 2g high acceleration 20mm move 16 2014 ACS Motion Control Ltd
Summary An increasing number of applications require nanometer level positioning PWM drives Industry Standard, Well-Known Certain constraints limit use for nm-level applications Linear drives Have long served high-end motion control niche Suffer from fundamental limitations, ultimately resulting in relatively high cost NanoPWM TM Revolutionary new technology, combines benefits of PWM and Linear drives Achievable performance is second to none 17 2014 ACS Motion Control Ltd
Thank You Jason Goerges General Manager, jasong@acsmotioncontrol.com 7444 W 78 th Street, Bloomington, MN 55439