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Understanding MOSFET Drivers for Motor Drive: Microchip AN898

This presentation delves into the essential aspects of MOSFET drivers for motor drive applications, focusing on Brush DC Motors. Learn about selecting power transistors, motor specifications, and the differences between MOSFETs and IGBTs for optimal performance.

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Understanding MOSFET Drivers for Motor Drive: Microchip AN898

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  1. Microchip AN898 Determining MOSFET Driver Needs for Motor Drive Applications Author: Jamie Dunn, Microchip Technology Inc. Presentation prepared by Nicholas Negrete

  2. Abstract This application note touches base on various motor drive applications, for our purpose this presentation summarizes only the information pertinent to Brush DC Motors. Determining MOSFET Driver Needs for Motor Drive Applications Microchip AN898 2

  3. Overview Stuff More stuff Even more stuff Are you done yet? There’s probably a little bit more I’m guessing were almost done One more point…. That should be about it Determining MOSFET Driver Needs for Motor Drive Applications Microchip AN898 3

  4. This presentation talks about the motor type and choosing the type of power transistor Determining MOSFET Driver Needs for Motor Drive Applications Microchip AN898 4

  5. “The first stage in selecting the correct power-switching element for your motor drive application is understanding the motor being driven.” Our goal is to power a 9” Advanced DC Motor(we should also keep in mind that we should be able to power a 6.7” Advanced DC motor, and a WARP 11” & 13” Motor – All are Brush DC Motors) Determining MOSFET Driver Needs for Motor Drive Applications Microchip AN898 5

  6. 9” Advanced DC Motor Determining MOSFET Driver Needs for Motor Drive Applications Microchip AN898 6

  7. 9” Advanced DC Motor Determining MOSFET Driver Needs for Motor Drive Applications Microchip AN898 7

  8. Keep in mind that: 1HP = 746Watts We need to know the ratings for voltage, current, and power ratings We especially need to know the “start up current” (AKA “stall current” or “locked rotor current”) This value can be up to three times the steady-state current. To answer this: the max voltage rating is 144V, max current rating is 600A, max power rating  P=iv  144v*600A=86.4kW Stall current: not yet found…. Determining MOSFET Driver Needs for Motor Drive Applications Microchip AN898 8

  9. MOSFET vs. IGBT Determining MOSFET Driver Needs for Motor Drive Applications Microchip AN898 • PLOSS=Iavg * VCE-SAT • VCE-SAT = Collector-Emittor saturation voltage • Iavg = Collector-Emittor average voltage • PN Junction Collector-Emitter • VCE-SAT decreases with temperature • Slower switching device = higher switching power loss • Turn-off edge is much slower • PLOSS=Irms2 * RDS-ON • RDS_ON = Drain-Source on-state Resistance • Irms = Drain-Source rms current • Resistive Drain-Source Channel • RDS-ON increases with temperature • Steady state power loss is the square so is higher loss than IGBT 9

  10. Generally Accepted Boundaries of Operations When comparing the IGBT and MOSFET For applications < 250V, MOSFETS are the device of choice. For applications > 1000V, IGBT are the device of choice. (Above 1000V, the RDS-ON of the MOSFET can no longer compete with the saturated junction of the IGBT) 1000V < For applications >250V, it becomes application specific choice that revolves around power dissipation, switching frequency and cost of the device. Determining MOSFET Driver Needs for Motor Drive Applications Microchip AN898 10

  11. Conclusion Motor Specs MOSFET/IGBT = MOSFET Drive Schematices Determining MOSFET Driver Needs for Motor Drive Applications Microchip AN898 11

  12. References Microchip Technology Inc. 2003, Determining MOSFET Driver Needs for Motor Drive Applications AN898 Determining MOSFET Driver Needs for Motor Drive Applications Microchip AN898 12

  13. NAU Motor Systems - Senior Design Capstone Team Christine Kuhlman, Jeremy King, Dan Eichenberger, Nicholas Negrete Website: http://www.cefns.nau.edu/Research/D4P/EGR486/EE/10-Projects/motor/ Email: nau.motor.systems@gmail.com YouTube: nau motor systems Determining MOSFET Driver Needs for Motor Drive Applications Microchip AN898 13

  14. We would like to thank our sponsors – Without them we would have not had such a great opportunity! Determining MOSFET Driver Needs for Motor Drive Applications Microchip AN898 14

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