

TEST SYSTEM DEVELOPMENT PRESENTATION & SUMMARYThis presentation & summary is a more detailed view of the test system development outlined in this TDA. The flexibility of this test system both in hardware and programmability allows the characterization of a variety of single and three phase bridge modules as well as substrate type power circuits. Included is a brief discussion on the equation sets developed and used for data collection. Included are graphical comparisons of the PWM techniques such as standard to grounded phase and triplen injection PWM schemes. Digital generation of the equation sets for three phase bridge circuits allows more control of load variations via current and or voltage feedback monitoring techniques that are easily implemented. The initial intent her was to test a device that was capable of driving an inductive load at 70 amps rms to simulate a field coil of a PMB DC motor, however, test results show that a 90 to 100 amps rms and beyond are feasible with standard cooling. I am available to discuss the development of test systems and special instrumentation required to perform these test. I can be reached through the contact form, just put Sal (JT) in the remarks section of the contact form and your email address. 
STANDARD THREE PHASE SINE WAVE EQUATION SETThree Phase Sinewave equation set used to generate the PWM waveforms. Note that is the 120° phase shift. If we observe the waveform we see that the maximum amplitude we can achieve from this is about 86% efficiency at any one point on the wave form. This translates to any phase being turned on only 86%. This is a loss in efficiency and the power would be dissipated in the power module creating heat problems.

STANDARD THREE PHASE EQUATIONS+3rd HARMONICThis equation set improves the efficiency of the maximum amplitude to almost 100% efficiency by adding a third harmonic, (triplen injection) to the equation set. This make the assumption that the phases are balanced and the triplen cancels out between phases. In summary this technique allows the full dynamic range vertically to be utilized. However it does require an offset and a gain factor as shown in order to normalize the equation set.

DUTY CYCLE ALGORITHM FOR EACH PHASEThe duty cycle of each phase is referenced to the actual amplitude for the phase equations and then calculated to fit the number of points in the period. The default value is 1000 points per PWM period per waveform point. The default playback clock rate is 25.00MHz, 50 nanoseconds. This defaults to a 13 millisecond sine wave period for 260,000 byte playback memory size, (1000 pulses per vertical resolution per point • 260 points per period). This allows for a 0.1% default duty cycle resolution per waveform point. The number of points for the PWM period is programmable as well as the number of points for the waveform period.
IF Va = 0 THEN
IF Vb = 0 THEN
IF Vc = 0 THEN 
GROUNDED PHASE ALGORITHM FOR EACH PHASE
SELECT CASE Vab
CASE IS > Vca
'
Vbc & Vca = 0 test 
Sine Grounded Phase

Triplen Grounded Phase

Sine Grounded Phase BRIDGE DRIVE

Triplen Grounded Phase BRIDGE DRIVE

Sine Grounded Phase BRIDGE DRIVE ON/OFF
TIMES

TRIPLEN Grounded Phase BRIDGE DRIVE ON/OFF TIMES

Empirical data, 0 TO 100 AMP rms 3 Ø Current
into a Delta configuration,

90 AMP rms 3Ø Current into the Delta
Load Configuration,

Comparison of the Sine and Sine + 3rd Harmonic
additive

THERMAL DISTRIBUTION OF THE MOUNTING MECHANISM FOR A
CERAMIC SUBSTRATE,

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