POWER INVERTER

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POWER INVERTER
Advisor Dr Yaroslav Koshka Team Leader Dustin
W. Bailey Team Members Daniel Martin, Jason
Horner, Min-chiat Wee
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Team Members and Responsibilities
Faculty Advisor Dr. Yaraslov Koshka
(Team Leader) Dustin Bailey -MS
Project -Documentation -Research -DC/DC Converter
Jason Horner -Research -DC/DC converter
Daniel Martin - Research -Inverter Circuit -PIC
Programming
Min-chiat Wee -Research -Inverter Circuit -PIC
Programming -Web Design
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Abstract

• Design a switch-mode power inverter that converts
  12VDC to 120VAC
• Develop a digital pulse-width modulation
  controller to output a near perfect sine wave
• Capable of supporting sensitive electronic
  devices of up to 150W without causing abnormal
  effects

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Motivations

• Digital pulse width modulation controller
  increases efficiency and reduces parts and size
• Digital PWM controller gives flexibility to
  change the output waveform
• Most true sine wave power inverters with 85-90
  efficiency, cost over 200. We will build an
  inverter with gt90 efficiency for less than 150

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Design Constraints

• Convert 12VDC to 120VAC
• 150W of continuous power 300W of peak power
• Efficiency gt 90
• THD lt 6
• Shield
• 1. Over voltage shutdown at 15VDC
• 2. Under voltage shutdown at 10VDC
• 3. Low voltage alarm at 10.7V

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Design Constraints (cont..)

• Physical dimensions will be 8 5 2.5
• Projected cost will be less than 150

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Basic Topology
PIC
Driver Circuit
Low Pass Filter
Half Bridge Inverter
DC-DC Converter
120VAC
12VDC
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DC-DC Converter

• Input 12VDC
• Outputs a regulated voltage
• Output voltage -170VDC rails of inverter
• -12VDC
  cooling fan and
  driver circuit
  
• -5VDC PIC
  
• 170VDC to the rails will have less than 2 ripple

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DC-DC Converter Topology

• Flyback Converter
• Boost Converter
• Simple
• No transformer to build or locate
• Less components

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DC-DC Converter Topology
Boost Converter

• V1I1 V2I2
• Duty Cycle, D 1-I2/I1 0.93
• V2 (1/C)(I2)(D)(Ts)
• C0.93 5.6 ?F
• I1 (1/L)(V1)(D)(Ts)
• L 720 ?H

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DC/DC Converter Simulation
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Pulse Width Modulation

• To generate a series of duty cycles to be
• programmed in a PIC

Reference sine wave
Comparator
PWM output
Control Frequency
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PWM Simulation
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Control Pulses
TR1
TR2
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Control Pulses
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PIC Program

• Generate 2 PWM pulses with a 180o phase
  difference
• A series of programmed duty cycles to output the
  desired waveforms (sine wave)
• Implement shield
• 1. Over voltage shutdown at 15VDC
• 2. Under voltage shutdown at 10VDC
• 3. Low voltage alarm at 10.7VDC

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PIC Algorithm
Initializes variable at power up
Yes
No
Voltage lt 15VDC
Power down DC/DC Converter PIC
Yes
No
Voltage 10.7VDC
Sound audible alarm
Yes
No
Voltage lt 10
Power down DC/DC Converter PIC
Output PWM pulses
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Driver Circuit

• Increases the voltage of the PIC controlled
  driving pulses

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Half Bridge Inverter

• Two sets of pulses 180o out of phase are used to
  switch the two MOSFETs
• Includes clamp diodes that protect the
  transistors from transients and improve overall
  efficiency.
• Outputs true sine wave

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Half Bridge Inverter
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Low Pass Filter

• Eliminates unwanted harmonics above the
  fundamental frequency of 60Hz

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Acknowledgement

• We would like to thank the following people for
  their support
• Dr. Yaraslov Koshka
• Dr. Mark Kinsler

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• Questions ??