1. Automated Control System
for the
Impulse Generator
Senior Design II
Midterm Presentation

2. Team Members Heather Bartlett Andrew Read Stephen Whitfield
-Trigger Package Design (PCB, PIC)‏
-Warning Lights
Andrew Read
-PC Software
-Communications
-System Design/Integration
Stanislaw Gryzbowski
Advisor
Stephen Whitfield
-Siren
-PCB packaging
Other Advisors:
-Mr. Clay Taylor
-Dr. Ginn

3. Outline Introduction Problem Solution Constraints Design Improvements
Testing plans
Questions

4. Problem The MSU High Voltage Lab is in need of a new
control system for its impulse generator.

5. Transformer / Rectifier
Current System
Gap Motor
Manually Controlled
Warning Light
75kVDC
variable
VAC
peak
Interlock
Transformer / Rectifier
Breaker
variac
Manually Controlled
240VAC (RMS)‏
Firing Circuit exists but is not connected
Stepper motor will be installed by HVL

6. Impulse Generator How does it work?
Gap Motor
An impulse generator produces short pulses of high-voltage.
‘n’ number of capacitors charged in parallel to a voltage ‘V’
Capacitors connected in series
System is triggered
Creates lightning!

7. Why is it important?
The impulse generator is used to run tests on equipment that can be put under high voltage stress. These tests help ensure protection to the equipment.
[2]
[1]

8. Transformer / Rectifier
New System
PC Control
Controller
Gap Motor V
v(t) i(t)‏
VAC
peak
Interlock
Animated slide
Firing Ckt
Transformer / Rectifier
PE-Based
Voltage Control
Breaker
Motor Indexer
+/-75kVDC
variable
240VAC (RMS)‏ 8

9. Practical Constraints
Health & Safety
Must tie into lab safety interlock system
New alarm siren should be loud, but not too loud
Sustainability
High Energy
Transients
Electromagnetic Interference

10. Transformer / Rectifier
Technical Constraints
Transformer Input
Voltage and Current monitoring
Transformer Output
+/-75kV DC (1% accuracy)‏
Input Voltage:
150 VAC
Output Voltage:
+75kVDC
VAC
peak
Transformer / Rectifier
+/-75kVDC
variable

11. Technical Constraints
Gap Spacing
3-7.7cm range on gap spacing
1mm tolerance C C C C
Firing Circuit
Stepper Motor
Stepper Motor
Indexer
To Controller 11

12. Technical Constraints
Voltage Controller
20A max current throughput
VAC output range

13. Outline Introduction Problem Solution Constraints Design Improvements
Testing plans
Questions

14. Warning Siren

15. Warning Siren Astable Operation - produces ‘square wave’
-output continually changes between ‘low’ and ‘high’
Monostable Operation
-features RC circuit to set the output duration

16. Warning Siren Produces between 50-60dB as requested by HVL
Loud enough to be heard in the lab, but not as loud as to disrupt neighboring classes
Triggered on command by microprocessor
Siren lasts for 3 seconds – long enough for a warning, but not too long to be an irritation

17. Transformer / Rectifier
Voltage Controller
UPS-Style
Voltage Control
Controller
Transformer / Rectifier
+/-75kVDC
variable
VAC
peak V
PC Control
Desired
Voltage
Duty cycle

18. Prototype Design Controller Power Supply 120 VAC Buck-Boost Stage
Inverter
Rectifier

19. Voltage Controller Testing In stages: DC Rectifier:
Operational up to 120VAC
Output of +/- 109VDC
Buck-Boost Converter:
Inverter:
Operational up to +/-109VDC
Output of 100VAC

20. Voltage Controller Testing In stages: I2C communication:
Fully Operational
DAC/PWM voltage control:
5VDC=70% duty cycle
0VDC=14% duty cycle
PWM Sine Wave:
Operational- slight jitter in output waveform.

21. Voltage Controller Testing
PCB populated in stages and supplied with 120VAC (50% design rating)
Low voltage components on separate PCB can be tested and troubleshot separately

22. Controller Design DAC Stepper Motor Driver MAX517 MLP08641 PIC18F4685
Output to Voltage Controller
DAC
MAX517
Input from Voltage Divider
SDA
SCL
AN0
Vdd
SDA
Clock +
Clock -
On/Off +
SCL
Direction +
Direction -
RB1
PIC18F4685
CCP1
RB3
RB2
RB5
RB0
Switch - Fully Open
RB4
Switch - Fully closed
Signal to Trigger
RC5
Gnd
RA4
RA5 RX TX
Warning Siren
Warning Light (LED)‏
Rout
Tin
MAX3222
RS232

23. Software Testing – Sphere Gap Calibration
Move sphere gap to fully closed position
User inputs the measured distance
Move sphere gaps to fully open position
Count the steps it takes to go from fully closed to fully open

24. Software Testing – Voltage Calibration
User specifies the applied charging voltage and stage voltage
User then applies the voltage manually
The stage voltage is measured from the ADC
Compute the ratio for charging voltage vs. stage voltage
Compute the ratio for known stage voltage vs. measured stage voltage

25. Software Testing – Regular Operation
Move sphere gap to fully closed position
Move stepper motor to desired
distance
Send signal for charging voltage
Wait for transformer output voltage
to equal the desired Stage Voltage
Yes
Signal is sent to triggering device
Turn warning Siren and Light on
Would you like to fire the trigger (Y/N)? No
Signal is not sent to triggering device

26. Controller Testing Stepper Motor Driver 200 steps/rev
PWM signal: one step/ period

27. Controller Testing/Packaging

28. References
C71-84A9809EC588EF21_arch1.jpg
lightning.jpg
Mohan, Ned. Power Electronics. Minneapolis, MN