RELIABILITY & SAFETY ANALYSISPRESENTED BY: ANDREW BATEK

Team # 15: Acoustic Storm

Interweaving the impressive visual power of electricity and the visceral emotion of music,

Acoustic Storm takes analog or digital audio input and outputs its own rendition using two varieties

of solid state tesla coils.

Project Description – Safety

Acoustic Storm will comprise multiple solid state tesla coils and associated power circuitry, among other things

These present safety hazards in the form of High power dissipation Shock and RF burn potential High Current and Dangerous Charge Storage Etc…

Ironically, these dangers exist when the system operates correctly. Low to Med. criticality failures make our device safer...

Current Block Diagram

Current Block Diagram

Criticality Levels

Low Criticality < 10 -2 failures per 106 unit – hours Loss of functionality without damage to remaining components No potential for user injury

Medium Criticality < 10 -3 failures per 106 unit – hours Loss of functionality and damage to separate device

components No potential for user injury

High Criticality < 10 -9 failures per 106 unit – hours Potential for user injury

Control Circuit - Microcontroller

Microcontroller - dsPIC33EP512MU810Model: λp = (C1πT + C2πE) πQ πL = 2.517

MTTF: ~45.3 yearsParameter name Description

 Value Comments

C1 Die Complexity Failure Rate

0.28 16 bit Microprocessor.

πT Temperature Factor 4.4 Using maximum extended temperature device rating

C2 Package Failure Rate .053 Less than 128 pins

πE Environmental Factor 0.5 For use in an area that is not mobile and has normal ambient temperatures

πQ Quality Factor 2.0 Assumed Quality Compliance

πL Learning Factor 1.0 Has been in production for > 2 years.

Power Supply – Boost Controller

Estimation of CCM operated boost converter Reliability [1]

λp = 77.59

MTBF = 12888 hours

Output Power: 800W &

CCM Operating Mode

λp (MOSFET) 76.686

λp (Output Diode)

.2

λp (Input Bridge) .103

λp (Input Inductor)

.509

λp (Output Capacitor)

.060

λp (Output Resistor)

.0297

Total λp 77.59

MTBF 12888 hours[1] G. Amer and S. S. Rao. “Estimation of Reliability of a Interleaving PFC Boost Converter” in Serbian Journal of Electrical Engineering, Vol. 7, No.2, Nov. 2010, pp 205-216Available: http://www.ieee.org/documents/ieeecitationref.pdf [4/3/2013]

Power Supply – Transformer

MOTs - various manufactures and typesModel: λp = λbπEπQ = .42

MTTF: ~271.8 years* Assumes we wound the secondary well

Parameter name Description 

Value Comments

λb Base Failure Rate 0.014 General operating temperature from 150-170°C – Worst Case Assumed

πE Environment Factor 1.0 For use in an area that is not mobile and has normal ambient temperatures

πQ Quality Factor 30 Non-spec power transformer

DRSSTC Coils

DRSSTC Coils present worse case than HFSSTC coilsModel: λp = λbπCπEπQ = .028

MTTF: ~4077 yearsParameter name Description

 Value Comments

λb Base Failure Rate 0.0014 Wire rated at 155°C – Assume worst Case operating temperature

πC Construction Factor 1.0 Not variable construction

πE Environment Factor 1.0 For use in an area that is not mobile and has normal ambient temperatures

πQ Quality Factor 20 Homemade – Assume Low Quality??

FMECA Chart for Selected Components

Failure No.

Failure Mode

Possible Causes

Failure Effects

Method of Detection

Criticality Remarks

MC1 Micro PWM output is incorrect

Software, burned out pins, external noise

Incorrect or nonexistent audio outputs

Auditory observation

Low

MC2 Micro Pin signal does not change

Software, burned out pin, external noise

Malfunction in peripherals

Visual or auditory observation

Low

MC3 MCLR is always logic low or high

Burned out pin, broken reset button, external noise

Micro is useless or can only be reset by removing power

Observation (oscilloscope)

Low

BC1 Controller fails to assert artificial ramp

Internal chip failure

Boost converter becomes unstable when duty cycle is > 50%. Potential to damage power supply

Observation of instability at high power

Power supply not working

Med Boost controller also has built in protection for boost circuit and should prevent this

FMECA Chart for Selected Components

Failure No.

Failure Mode

Possible Causes

Failure Effects

Method of Detection

Criticality Remarks

BC2 Boost Controller Output remains constant

Internal chip failure

MOSFET will not be driven – Boost converter will not function

No high voltage power supply output

low

MOT1 Transformer failure

Short between coils, excess current

Power supply will cease to function

No power supply output

Low

MOT2 Transformer power rating is GREATLYexceeded

Abnormal current caused by fault, external surge

Copper fuses, vaporizes, and is ejected from transformer

Observation High Highly, repeat, Highly unlikely

TC1 Tesla Coils Short Circuit between coils

Device Temperature is hot enough to melt insulation and possibly coil wire

Coils stop working because the resonant circuit is broken

No coil output and/or visual inspection of coils

Med Coils and potentially other parts need replacement

Special Note: Human Error

The majority of the high criticality “failures” of our design will be dependent upon human error

These occurrences cannot be analyzed in the same way as actual device failures

Goal is to ensure that human error never happens through: Safety Design Standard Operating Procedures approved by REM …I’ll save you the rest of the ~24 pages