Transformer Training Board Power Supply

1
Transformer Training BoardPower Supply

• Advisor Dr. Michael Mazzola
• Team Members Gary Hutson, James Roberts, James
  Jackson, and Kenny Beverin

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Team Members
Gary Hutson
James Roberts
Kenny Beverin
James Jackson
3
Team Responsibilities
Gary Hutson Website Management DC Power Conversion
Kenny Beverin Stock Market Analysis Power Point
James Jackson Documentation Gate Driver Circuit
James Roberts PIC Programming Packaging

4
Basic Topology
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Design Requirements

• The 3-phase output voltage THD should
• be limited to 5.
• The phase to phase voltage should be regulated
  to 43 volts /- .5 volts
• The weight limit is 20 pounds.
• The size should be 12 cubed.

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Rectifier (Unfiltered)
Amplitude 170V Average 108V
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DC Link Filter
10 Ripple Voltage Filter values C 91.7uF L
109.6mH
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Rectifier Output (Filtered)
Ripple Voltage 7.35
Ripple Voltage 12.6 V Peak Voltage 165 V
Ripple Voltage 7.64
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DC supplies

• 5 volt supply
• This powers the micro controller that produces
  control pulses
• 12 volt supply
• This powers the cooling fans and the gate driver
  circuit
• 150 volt supply
• This powers the inverter bridge

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Circuit Protection

• Input
• 5 Amp AC fuse
• Output
• 3 mini-magnetic circuit breakers, 5 Amp

11
Design Change

• Removed the entire control circuit
• Replaced it with one Micro Controller
• All other components remained the same

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New control topology
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PIC Program

• Program that generates 6 PWM pulses
• 3 pairs of complimentary pulses
• Each pair is 120 degrees from the other two
• Produces output pulses that cycle through a table
  of duty cycle values
• Duty cycle values can be changed to produce
  different output waveforms

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PWM vs. Square Wave
Result Smaller Output Filter Components
Switching Frequency
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PWM Method

• PWM Pulses per waveform 51
• Sine wave output 60Hz
• Switching Frequency 60 x 51 3.06kHz

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Pulse Duty Cycle Determination
ma Vref / Vtri
For 3-Phase Inverter V(line to line)out 0.612
ma Vd
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Actual 3-Phase Control Pulses
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Driver Circuit

• A driver will be used for two reasons
• It will isolate the high side MOSFETs from the
  high side control pulses.
• It will increase the control pulse voltage to a
  level needed to switch the MOSFETs.

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Driver Circuit
Bottom Ctrl. Pulse
Upper Ctrl. Pulse
Upper Transistor Pulse
Lower Transistor Pulse
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Output from Driver
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3-Phase Half-Bridge
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Unfiltered Output
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Low Pass Filter

• Designed to reduce THD to less that 5
• Corner Frequency 620Hz
• L 125mH
• C 0.53mF

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Final Output
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Final Output
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Layout
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Acknowledgements

• Dr. Mazzola for his continued support
• Robert Cheney from Alabama Power
• Roger D. Marcus from Alabama Power