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76
Doc/main.tex
@ -42,14 +42,14 @@
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\lipsum[3-4]
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\section{Methodology}
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\section{Methodology} \label{section:methodology}
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To characterize the system, several tests have been performed. The
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characteristics of interest are the following:
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\begin{enumerate}[nosep]
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\item Efficiency
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\item Noise
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\item Ripple characteristics
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\item Transients
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\item Start up
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\end{enumerate}
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In this section a test or measurement will be described for each of the above
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characteristics.
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@ -60,7 +60,7 @@
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were chosen to give characterize the circuit over a broad range of conditions.
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\subsection{Efficiency}
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\subsection{Efficiency} \label{section:efficiency}
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\begin{Figure}
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\centering
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\includegraphics[scale=0.34]{SCHEMATIC_EFFICIENCY.png}
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@ -94,11 +94,11 @@
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\subsubsection{Peak to peak}\label{section:peak_to_peak}
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Peak to peak is the simplest way to look at noise. The signal has a stationary
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mean over the period of 1 millisecond. Thus the highest measured value can be
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mean over the period of 1 millisecond. Thus, the highest measured value can be
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subtracted from the lowest measured value.
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\subsubsection{Standard Deviation}
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\subsubsection{Standard Deviation}\label{section:standard_devation}
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The second metric used to measure noise was the standard deviation.
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Unlike, peak to peak it givesa better impression of the noise over a longer
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signal. SD can be calculated using equation \ref{eq:sd}.
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@ -111,7 +111,8 @@
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Where $x[i]$ is each voltage measurement, $\mu$ is the mean of the signal and
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$N$ is the total amount of samples.
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\subsection{Ripple characteristics}
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\subsection{Ripple characteristics}
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\begin{Figure}
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\centering
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\includegraphics[scale=0.5]{RIPPLE.png}
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@ -130,7 +131,7 @@
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section \ref{section:peak_to_peak}.
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To measure the frequency of the signal using an FFT, it had to be pre-processed
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first using a Hamming window this eliminates sharp edges at the edge of the
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first using a Hamming window, this eliminates sharp edges at the edge of the
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measurement, causing unwanted frequencies to appear in the frequency domain.
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\begin{equation}
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\label{eq:hamming}
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@ -141,12 +142,67 @@
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sample in the signal can be multiplied by the corresponding value in the window,
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preparing the signal for the FFT.
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\subsection{Transients}
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The last measurements were hocus pocus
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\subsection{Start up}
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The last characteristics is the start up, specifically the different rise times
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under load. The voltage was measured at the output as the supply was turned on.
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Different rise times can be defined. First off, $\tau$ and $2 \tau$ were
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defined as $63\%$ and $95\%$ respectively. Further more, 'rise time' was defined
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as $90\%$, a metric used often in control theory.
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One problem that occured during the measurements, is that the aforementioned
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ripples and noise would cause erroneous readings. As such, the signal was
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filtered using a low pass filter, reducing the high frequencies from the
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measurement.
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\section{Results}
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\lipsum[1-2]
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In this section the results from section \ref{section:methodology} will be
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discussed, as well as discuss some probable causes for unknown or unintended
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results.
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\subsection{Efficiency}
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\begin{Figure}
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\centering
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\includegraphics[scale=0.5]{EFFICIENCY_PERCENTAGE.jpg}
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\captionof{figure}{WIP}
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\label{fig:efficiency}
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\end{Figure}
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\noindent The results for the efficiency measurements, as described in section
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\ref{section:efficiency} are displayed in figure \ref{fig:efficiency}.
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The $7V$ measurements follow a predictable curve, however, the $3.3V$ makes
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an unexplained jump back to a higher percentage.
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\subsection{Noise}
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\begin{Figure}
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\centering
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\includegraphics[scale=0.5]{SNR_LOADVSPKPK.jpg}
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\captionof{figure}{WIP}
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\label{fig:noise_pkpk}
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\end{Figure}
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\noindent The results for the efficiency measurements, as described in section
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\ref{section:peak_to_peak} are displayed in figure \ref{fig:noise_pkpk}.
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The peak to peak voltage is a significant fraction of the output voltage,
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with $3V$ peaking at $33\%$. It seems there is a relation between peak to
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peak voltage and the output voltage as well, as $7V$ has more noise than
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$3.3V$
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\begin{Figure}
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\centering
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\includegraphics[scale=0.5]{SNR_LOADVSSD.jpg}
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\captionof{figure}{WIP}
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\label{fig:noise_sd}
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\end{Figure}
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\noindent The results for the efficiency measurements, as described in section
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\ref{section:standard_devation} are displayed in figure \ref{fig:noise_sd}.
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Although the voltage peaks are high, the noise's standard deviation is in the
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range of millivolts. The trend that a higher output voltage has more noise
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is continued in this graph.
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\subsection{Ripple}
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\section{Conclusion}
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\lipsum[3-4]
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