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rapport/introduction.tex

@@ -2,7 +2,7 @@
 \chapter{Introduction}\label{cha:intro}
 The standards ISO~7637, \emph{Road vehicles -- Electrical disturbances from conduction and coupling}, and ISO~16750, \emph{Road vehicles -- Environmental conditions and testing for electrical and electronic equipment}, are international standards that apply to equipment in road vehicles with a nominal supply voltage of \SI{12}{\volt} or \SI{24}{\volt}. The standards states, here put in a very condensed form, that the product shall withstand a sufficient amount of disturbances applied to its power supply. The reason for this is that there can be voltage surges and noise in a vehicle's power supply lines. In general, the source of disturbances and noise in a vehicle origins from inductance in other devices connected to the power line, the cables and the vehicles alternator in combination with switching of loads or the supply. \cite{iso_7637_2, iso_16750_2}
 
-To test if a product comply with this standard, there is equipment that simulates different events on the power supply. The standard defines the different scenarios, raise and fall times of test pulses, repetition times etc. It also defines the functional requirements of the equipment during these tests for what is considered a passed or a failed test. \cite{iso_7637_2, iso_16750_2}
+To test if a product comply with this standard, there is equipment that simulates different events on the power supply. The test events consists of voltage pulses that are applied to the DUT, device under test. The pulses of interest in this paper are denoted pulse 1, pulse 2a, pulse 3a, pulse 3b and load dump test A. The standard defines the different scenarios, raise and fall times of test pulses, repetition times etc. It also defines the functional requirements of the equipment during these tests for what is considered a passed or a failed test. \cite{iso_7637_2, iso_16750_2}
 
 \section{Motivation}
 The standard defines all the timing requirements that must be met, and also specifies the load conditions for which the requirements apply \cite{iso_7637_2}. From time to time the standards are revised, which may alter the requirements form the previous versions of the standard. New equipment is guaranteed by its manufacturer to do the tests according to the latest standard, as long as all the maintenance instructions are followed which might include sending the equipment in for calibration and service. New equipment might not be affordable by smaller test labs, and can thus inhibit labs from performing tests for this standard.

rapport/methods.tex

@@ -3,9 +3,11 @@
 This chapter covers the methodologies used during the project. To man dude! \todo[ta bort detta]
 
 \section{Prestudy}
-During the project efforts were made to find relevant research using Linköping University Library's\footnote{\url{https://liu.se/en/library}} and Google Scholar's\footnote{\url{https://scholar.google.se/}} search engines. Among the keywords used in searching were \emph{verification equipment}, \emph{test equipment}, \emph{automatic test}, \emph{automatic verification}, \emph{iso equipment}, \emph{electrical verification}, \emph{curve fitting}, \emph{double exponential function}, \emph{}, \emph{}
+During the project efforts were made to find relevant research using Linköping University Library's\footnote{\url{https://liu.se/en/library}} and Google Scholar's\footnote{\url{https://scholar.google.se/}} search engines. Among the keywords used in searching were;
 
-\todo[Skriv färdigt nyckelordsdelen]
+\squareit{ \emph{verification equipment}, \emph{test equipment}, \emph{automatic test}, \emph{automatic verification}, \emph{iso equipment}, \emph{electrical verification}, \emph{curve fitting}, \emph{double exponential function}, \emph{}, \emph{}}
+
+\todo[Skriv färdigt nyckelordsdelen och presera dem på ett snyggt men platseffektivt sätt]
 
 Since the equipment intended for this project was untested before the project start, the first step was to hook it up and make some initial measurements to be able to decide the continuation of the project.
 
@@ -43,11 +45,7 @@ Pulse 3a and Pulse 3b was measured using the attenuators described in \autoref{s
 \squareit{Alternatives and choices. Try finding articles on human error maybe. Make plenty of nice figures.}
 The total number of tests needed to verify the testing equipment before each product test is 14, according to \autoref{tab:verification-list}. There are in total three different values for dummy loads, in practice these will be represented by three different high power dummy loads and two high frequency attenuators for pulse 3a and pulse 3b.
 
-The following test architectures were considered, together with the external supervisor at the company. In the end the 3rd alternative was chosen, as explained in \autoref{result-test-architecture}. To design Alternative 3 some utilities needs to be designed, namely:
-\begin{itemize}
-    \item Relay box, the fixture with embedded attenuators that are to be attached to the front of the CNA.
-    \item Match box, the dummy loads with some relays to be able to switch between them.
-\end{itemize}
+The following test architectures were considered, together with the external supervisor at the company.
 
 Additionally there needs to be some sort of measurement fixture for evaluating the verification equipment.
 
@@ -58,10 +56,10 @@ The test can be performed semi-automatically by means of the existing equipment
 
 The main advantage of this is that it would probably require the least amount of time for development of the automation software. It also doesn't need any extra hardware except from the dummy loads needed to do the verification.
 
-The biggest disadvantage is that it would be very cumbersome to perform and also very prone to human error. If the verification list is studied carefully one can minimise is to five reconnections after the initial connections are made, for example in the following order: No load, \SI{2}{\ohm}, \SI{10}{\ohm}, \SI{50}{\ohm} low frequency, \SI{50}{\ohm} high frequency, \SI{1}{\kilo\ohm} high frequency.
+The biggest disadvantage is that it would be very cumbersome to perform and also very prone to human error. If the verification list is studied carefully one can minimize it to five reconnections after the initial connections are made, for example in the following order: No load, \SI{2}{\ohm}, \SI{10}{\ohm}, \SI{50}{\ohm} low frequency, \SI{50}{\ohm} high frequency, \SI{1}{\kilo\ohm} high frequency.
 
 \subsection{Alternative 2 -- Fully automatic rig external attenuators}
-To accurately measure Pulse 3a and Pulse 3b, the probes should be attached as close as possible to the generator because of the high frequency, to avoid influence of the connecting wires. This could be accomplished by the means of a fixture that is attached directly to the generator, which can switch the pulses to the different loads or to the measurement outputs.
+To accurately measure Pulse 3a and Pulse 3b, the probes should be attached as close as possible to the generator because of the high frequency, to avoid influence of the connecting wires \cite{some_good_reference_for_measurement_techniques} \todo[find source to this]. This could be accomplished by the means of a fixture that is attached directly to the generator, which can switch the pulses to the different loads or to the measurement outputs.
 
 The dummy loads for all pulses, but Pulse 3a and Pulse 3b, will need to be put in a separate enclosure because of the power dissipation needed. The proposed architecture is depicted in \autoref{fig:automatic-rig-1}.
 
@@ -74,6 +72,12 @@ The disadvantage to this setup is that the fixture needs to be designed, making
 \subsection{Alternative 3 -- Fully automatic rig with embedded attenuators}
 To cope with the high voltage exposure, of alternative 1, the high frequency attenuators can be embedded inside the switching fixture, removing the need for high-voltage connectors. \autoref{fig:automatic-rig-2}.
 
+To design Alternative 3 some utilities needs to be designed, namely:
+\begin{itemize}
+    \item Relay box, the fixture with embedded attenuators that are to be attached to the front of the CNA.
+    \item Match box, the dummy loads with some relays to be able to switch between them.
+\end{itemize}
+
 \todo[Fint schema här]
 
 The advantage of this, on top of the advantages of alternative 2, is that there is no longer need for external attenuators and that the connectors will no longer expose high voltage.
@@ -86,7 +90,7 @@ Each dummy load must withstand the applied test pulses, and preferably the worst
 The dummy loads consists of one or more resistors. When determining whether the resistors withstands the test pulses, the parameters of interest are power dissipation, maximum voltage and maximum energy applied over time.
 
 \subsection{Components}
-At first the momentary worst case powers and voltages were calculated by hand, to the values seen in \autoref{tab:dummy_load_worst_case}. But to find components that can handle these momentary powers proved very difficult, and it is not necessary since the pulse power is varying over time and the impulse voltage does not stress the components as much as a constant voltage would do.
+At first the momentary worst case powers and voltages were calculated by hand, to the values seen in \autoref{tab:dummy_load_worst_case}. But to find components that can handle these momentary powers proved very difficult, and it is not necessary since the pulse power is only high for a very short time. 
 
 One manufacturer of thick film resistors, namely Vishay, specifies its overload capability in a graph with energy over time in the datasheet, which was easier to compare against using LTSpice to simulate the energies for the different loads, according to \autoref{graph:dummy_load_energy}. The simulated value was then divided by the value specified in the datasheet to get the minimum number of resistors required to share the load. Some possible combinations of available resistor values were considered to reach the desired load resistance, before the final configuration were decided according to \autoref{fig:final-dummy-loads}.
 
@@ -135,7 +139,7 @@ When the PCB was delivered, it was visually inspected before assembling. Some mo
 When the dummy loads had been assembled, their resistances were determined using four wire resistance measurement directly at the PCB's connection points, as seen in \autoref{fig:four-wire-measurement}. With this technique, one can neglect the resistance in the cables used for measuring which can have a significant affect when measuring low resistance loads \cite{book:measurment-techniques}.
 
 
-\section{Design of the switching fixture and embedded attenuators}
+\section{Design of the switching fixture and the embedded attenuators}
 The chosen implementation requires a fixture that switches and attenuators, which purpose is to switch the pulse to the desired attenuator or to the dummy load. It must be able to handle the momentary pulse energies and voltages and should not distort the pulse.
 
 \subsection{Attenuators}
@@ -157,7 +161,7 @@ With the minimum number of discrete resistors needed for each ideal resistor kno
 
 When the number of resistors and its constellations was decided, all of the discrete ideal resistors were replaced with non-ideal models in the simulation software. Then the attenuators were checked in frequency domain, as well as how the pulses were affected in time domain.
 
-\subsection{PCB}
+\subsection{PCB for the relay box}
 \todo[Fin bild på designprocess av PVB, säkerhetsavstånd etc]
 
 Since the attenuators consits of SMD, surface-mount device, resistors, it was decided to design a PCB for this purpose. This also gives good control of the lengths of the conductors, which is of importance when designing for higher frequencies.
@@ -172,7 +176,7 @@ Before the PCB was sent for manufacturing, it was also printed in 1:1 scale as t
 
 When the PCB was delivered, it was visually inspected before assembling. Some modifications were required to fulfill the clearance criteria, these were made using a rotary multitool to machine away the undesired part of the traces.
 
-\subsection{Measurement}
+\subsection{Measurement of the relay box}
 Since the relay card will be used in measuring pulses with short rise times, it is of importance to know that it does not distorts the signal too much. It is desired to measure the magnitude response in the frequency domain, as well as the test pulse in time domain.
 
 To measure the magnitude response, a so called S21 measurement was performed using the network analyzer ZVL that is introduced in \autoref{sec:rohde_schwarz_zvl}. To be able to connect the network analyzer, a fixture was made to mimic the front panel of the CNA~200. A programmable relay card was used to control the relays during the testing. The setup can be seen in \autoref{fig:relay_card_measurement_s21}.

rapport/results.tex

@@ -7,7 +7,7 @@ Since not much was known about the project at this time, it was difficult to fin
 
 \section{Initial measurement of the old equipment}
 
-The result from the initial measurements are presented, along with the limits, in \autoref{tab:initial_measurements} and \autoref{tab:initial_measurements_sna}.
+The result from the initial measurements are presented, along with the limits, in \autoref{tab:initial_measurements} without the CNA~200 connected and in \autoref{tab:initial_measurements_cna} with the CNA~200 connected.
 
 \begin{table}[h]
 \begin{adjustbox}{width=\columnwidth,center}
@@ -59,17 +59,24 @@ The result from the initial measurements are presented, along with the limits, i
 
 \section{Test architecture}
 \label{result-test-architecture}
-The 3rd alternative was chosen because of the convenience of a fully automatic system and because of the electrical safety that alternative 2 would pose.
+The 3rd alternative was chosen because of the convenience of a fully automatic system and because of the electrical safety hazard that alternative 2 would pose due to its live measurement connectors.
 
 \section{Design of dummy loads}
-The values measured on the dummy loads are presented in \autoref{tab:four-wire-result}.
+\subsection{Components}
+\todo[förklara komponentval]
+
+\subsection{PCB}
+\todo[Peta in bilder]
+
+\subsection{Measurement results}
+The resistance at the dummy loads are presented in \autoref{tab:four-wire-result}.
 
 \begin{table}[h]
 %\begin{adjustbox}{width=\columnwidth,center}
     \centering
     \begin{tabular}{|l|r|r|} 
         \hline
-        Dummy load (\si{\ohm}) & Measured $R$ (\si{\ohm}) & Tolerance (\si{\percent}) \\
+        Nominal (\si{\ohm}) & Measured $R$ (\si{\ohm}) & Tolerance (\si{\percent}) \\
         \hline
         2   & $2.004$   & 0.2   \\
         10  & $9.973$   & 0.27  \\
@@ -77,22 +84,23 @@ The values measured on the dummy loads are presented in \autoref{tab:four-wire-r
         \hline
     \end{tabular}
 %\end{adjustbox}
-    \caption{The measured resistance of the dummy loads.}
+    \caption{The measured resistance of the dummy loads, and the tolerance compared to the nominal values.}
     \label{tab:four-wire-result}
 \end{table}
 
 \section{Design of the switching fixture and embedded attenuators}
 
-
  Vishay's CRCW-HP series fitted this description and were easily available.
  
- The \SI{54.7}{\deci\bel} attenuator was divided into two \SI{27.35}{\deci\bel} $\Pi$ attenuator links. When the closest values for the resistors had been chosen, using \SI{56}{\ohm} as shunt resistors and \SI{56}{\ohm} in series, the final attenuation was \SI{53.66}{\deci\bel} for the two links according to the simulation, seen in \autoref{fig:ltspice-att-ideal-54}. The input and output resistance was 
+ \subsection{Attenuators}
+ 
+ The \SI{54.7}{\deci\bel} attenuator was divided into two \SI{27.35}{\deci\bel} $\Pi$ attenuator links. When the closest values for the resistors had been chosen, using \SI{56}{\ohm} as shunt resistors and \SI{560}{\ohm} in series, the final attenuation was \SI{53.66}{\deci\bel} for the two links according to the simulation, seen in \autoref{fig:ltspice-att-ideal-54}. The input and output resistance was 
 
-Nice graphs.
 
 The \SI{60.1}{\deci\bel} attenuator was divided into one \SI{27.35}{\deci\bel} $\Pi$ attenuator links \SI{32.75}{\deci\bel}. When the closest values for the resistors had been chosen, using \SI{56}{\ohm} as shunt resistors and \SI{56}{\ohm} in series, the final attenuation was \SI{53.66}{\deci\bel} for the two links according to the simulation, seen in \autoref{fig:ltspice-att-ideal-54}. The input and output resistance was 
 \autoref{discussion_attenuators}
 
+\subsection{Measurements}
 
 \begin{figure}
 	\centering
@@ -139,6 +147,7 @@ The \SI{60.1}{\deci\bel} attenuator was divided into one \SI{27.35}{\deci\bel} $
 \end{figure}
 
 \section{Analysis}
+Nah
 
 
 

rapport/theory.tex

@@ -4,7 +4,7 @@
 This chapter introduces the theory and facts that are related to this project. It describes the necessary parts of the ISO standards, measurement theory and analysis of acquired data.
 
 \section{Previous research}
-No previous research relevant to the reuse of test equipment was found. Though there is research available on smaller specific topics that are covered by this project, such as measurement techniques and curve fitting. Such findings are used in this theory chapter. 
+No previous research relevant to the reuse of test equipment was found. Though there is research available on smaller specific topics that are covered by this project, such as measurement techniques and curve fitting. Those findings are presented in this theory chapter. 
 
 \section{ISO standards}
 The ISO organisation, International Organization for Standardization, was founded in 1947 and has since published more than 22,500 International Standards. ISO standards does not only cover the electronic industry, but almost every industry. The purpose of the standards is to ensure safety, reliability and quality of products in a unified way, making international trade easier. The name ISO comes from the Greek word \emph{isos}, which means \emph{equal}.
@@ -25,14 +25,14 @@ conduction and coupling}, concerns the electrical environment in road vehicles.
 
 Part 1, \emph{Definitions and general considerations}, defines some abbreviations and technical terms that are used throughout the standard. It also intended use of the standard. \cite{iso_7637_1}
 
-Part 2, \emph{Electrical transient conduction along supply lines only}, defines the test procedures related to disturbances that are carried along the supply lines of a product. Both emission, disturbances created by the DUT (device under test), and immunity, the DUT's capability to withstand disturbances, are covered. This part defines the test pulses that are of interest for this project, and the verification of them. \cite{iso_7637_2}
+Part 2, \emph{Electrical transient conduction along supply lines only}, defines the test procedures related to disturbances that are carried along the supply lines of a product. Both emission, disturbances created by the DUT, and immunity, the DUT's capability to withstand disturbances, are covered. This part defines the test pulses that are of interest for this project, and the verification of them. \cite{iso_7637_2}
 
 Part 3, \emph{Electrical transient transmission by capacitive and inductive coupling via lines other than supply lines}, defines immunity tests against disturbances on other interfaces that the power supply. It focuses on test setups and different ways of coupling the signals. \cite{iso_7637_3}
 
-Part 5, \emph{Enhanced definitions and verification methods for harmonization of pulse generators according to ISO~7637}, proposes an alternative verification method of the test pulses defined in ISO~7637-2. The main difference from the method described in ISO~7637-2 is that $U_A$ should not only be 0~V during the verification, but also be set to $U_N$. This will not be considered deeply in this report, since it is only a proposal and makes the verification equipment more difficult. \cite{iso_7637_5}
+Part 5, \emph{Enhanced definitions and verification methods for harmonization of pulse generators according to ISO~7637}, proposes an alternative verification method of the test pulses defined in ISO~7637-2. The main difference from the method described in ISO~7637-2 is that the DC voltage, $U_A$, should not only be 0~V during the verification, but also be set to the nominal voltage, $U_N$. This will not be considered deeply in this report, since it is only a proposal and makes the verification equipment more difficult. \cite{iso_7637_5}
 
 The ISO~16750, \emph{Road vehicles -- Environmental conditions and testing for electrical and electronic equipment}, concerns different environmental factors that a product might face in a vehicle, such as mechanical shocks, temperature changes and acids. Part 2, \emph{Electrical Loads}, of the standard deals with some electrical aspects that was previously part of the ISO~7637 standard. This is the only part of ISO~16750 that will be considered.
-\cite{iso-16750-1, iso_16750_2}
+\cite{iso_16750_1, iso_16750_2}
 
 \section{Test pulses}
 
@@ -40,21 +40,21 @@ All test pulses defined in ISO~7637 and ISO~16750 are supposed to simulate event
 
 The test pulses of interest defined in ISO~7637 are denoted \emph{Test pulse 1}, \emph{Test pulse 2a}, \emph{Test pulse 3a} and \emph{Test pulse 3b}. The test pulse of interest defined in ISO~16750 is denoted \emph{Load dump Test A}. There are more pulses and tests defined in these standards, but those are not in the scope of this project.
 
-The general characteristics in common for all pulses are the surge voltage $U_s$, the rise time $t_r$, the pulse duration $t_d$ and the internal resistance $R_i$. For pulses that are supposed to be applied several times, $t_1$ usually denotes the time between two consecutive pulses.
+The general characteristics in common for all pulses are the DC voltage $U_A$, the surge voltage $U_s$, the rise time $t_r$, the pulse duration $t_d$ and the internal resistance $R_i$. The internal resistance is only in series with the pulse generator, not the DC power source. For pulses that are supposed to be applied several times, $t_1$ usually denotes the time between two consecutive pulses.
 
-An important note to make is that the definition of the surge voltage, $U_s$, differs in ISO~7637 and ISO~16750 as seen in \autoref{fig:us_difference}. In this report, only the definition from ISO~7637 is used.
+An important observation is that the definition of the surge voltage, $U_s$, differs in ISO~7637 and ISO~16750 as seen in \autoref{fig:us_difference}. In this report, only the definition from ISO~7637 is used.
 
 \todo[Bild med kurvornas parametrar, båda ISO standardernas definitioner]
 
 \subsection{Test pulse 1}
-This pulse simulates the event of the power supply being disconnected to open, while the DUT is connected to other inductive loads. The other inductive loads will generate a voltage transient of reversed polarity, trying to maintain the current that was previously flowing through it.
+This pulse simulates the event of the power supply being disconnected while the DUT is connected to other inductive loads. This leads to the other inductive loads generating a voltage transient of reversed polarity to the DUT's supply lines.
 
 In the standard there are two additional timings associated to this pulse, $t_2$ and $t_3$, which are defining the disconnection time for the power supply during the voltage transient. In practice $t_3$ can be very short, specified to less than 100 µs, and the step seen in \autoref{fig:pulse1} might be too short to be clearly distinguishable when seen on a oscilloscope.
 
 \todo[Två bilder, en på kurvan och en på kretsen som orsakar den. En tabell med parametervärden.]
 
 \subsection{Test pulse 2a}
-This pulse simulates the event of a load, parallel to the DUT, being disconnected. The inductance in the wiring harness will then generate a positive voltage transient trying to maintain the current that was previously flowing through it.
+This pulse simulates the event of a load, parallel to the DUT, being disconnected. The inductance in the wiring harness will then generate a positive voltage transient on the DUT's supply lines.
 
 \todo[Två bilder, en på kurvan och en på kretsen som orsakar den. En tabell med parametervärden.]
 
@@ -239,6 +239,8 @@ Combined rise time \cite{vilken_bok_menar_jag}.
 high speed digital design 83
 
 \subsection{Oscilloscope and probes}
+\todo[Put good theory here]
+
 An oscilloscope measures voltage over time, using voltage probes. 
 
 The oscilloscope has properties bandwidth...
@@ -248,7 +250,7 @@ The probe also has properties..
 Commercial probes are expensive
 
 \subsection{Measurement errors}
-Put good theory here
+\todo[Put good theory here]
 
 \subsection{RF Attenuators}
 Linearity, tolerances, power, combinations of resistors, impedances