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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.
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-\todo[ta bort denna todo]
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\section{Previous research}
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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.
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\section{ISO standards}
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-The ISO organisation, International Organization for Standardization, was founded in 1947 and has since published more than 22500 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}.
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+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}.
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\cite{site:iso_about}
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-The standards are developed and maintained by Technical Committees consisting of, amongst others, experts in the area that the standard \cite{site:iso_who_develops_standards}. A new standard is only developed when there exists a need for this from the industry or other groups that may require it \cite{site:iso_developing_standards}. Existing standards are automatically scheduled for review five years after its last publication, but can manually be reviewed before that time by the committee \cite{iso_guidance_review}. During the review process, it will be decided if the standard is still valid, need to be updated or if it should be removed \cite{iso_guidance_review}.
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+A standard is developed and maintained by a Technical Committee, TC, consisting of, amongst others, experts in the area that the standard concerns \cite{site:iso_who_develops_standards}. A new standard is only developed when there exists a need for this from the industry or other groups that may require it \cite{site:iso_developing_standards}. Existing standards are automatically scheduled for review five years after its last publication, but can manually be reviewed before that time by the committee \cite{iso_guidance_review}. During the review process, it will be decided if the standard is still valid, need to be updated or if it should be removed \cite{iso_guidance_review}.
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-The naming convention used for ISO standards is of the form \emph{number-part:year}, where the \emph{number} is the identifier to the unique ISO standard, \emph{part} denotes the part of the standard if it is divided into several parts and \emph{year} is the publishing year. For example, the name \emph{ISO~7637-2:2011} refers to part 2 of the ISO~7637 standard published in 2011, whilst \emph{ISO~7637-2:2004} would refer to an earlier version of the exact same document published in 2004.
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+The naming convention used for ISO standards is in the format \emph{number-part:year}, where the \emph{number} is the identifier to the unique ISO standard, \emph{part} denotes the part of the standard if it is divided into several parts and \emph{year} is the publishing year. For example, the name \emph{ISO~7637-2:2011} refers to part 2 of the ISO~7637 standard published in 2011, whilst \emph{ISO~7637-2:2004} would refer to an earlier version of the exact same document published in 2004.
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-To get hold of a copy of a standard, one need to buy it from ISO or one of its retailers. \cite{iso-shopping-faqs}
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-%https://www.iso.org/shopping-faqs.html besökt 2019-06-19
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+To get hold of a copy of a standard, one need to buy it from ISO store or from a national ISO member. \cite{site:iso_shopping_faqs}
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\section{ISO~7637 and ISO~16750}
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\todo[fundera på uppdelningen av stycken och underrubriker här, och allmän formattering]
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\textbf{The ISO~7637 standard}, \emph{Road vehicles — Electrical disturbances from
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conduction and coupling}, concerns the electrical environment in road vehicles. The standard consists of, at the time of writing, four parts.
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-Part 1, \emph{Definitions and general considerations}, defines some abbreviations and technical terms that are used throughout the standard. It also describes the scope of where the standard is intended to be applied. \cite{iso_7637_1}
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+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}
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-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, and the verification of the same, that are of interest to this project. \cite{iso_7637_2}
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+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}
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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}
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@@ -39,30 +36,30 @@ The ISO~16750, \emph{Road vehicles -- Environmental conditions and testing for e
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\section{Test pulses}
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-All test pulses defined in ISO~7637 and ISO~16750 are supposed to simulate events that can occur in a real vehicle's electrical environment, that products must be able to withstand. The properties of these test pulses are well defined, to allow for unified testing regardless of which test lab that performs the test. In the real world, however, the disturbances might of course differ from the test pulses since a real case environment is not controlled. \cite{iso_7637_2,iso_16750_2, comparison_iso_7637_real_world}
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+All test pulses defined in ISO~7637 and ISO~16750 are supposed to simulate events that can occur in a real vehicle's electrical environment, that equipment must be able to withstand. The properties of these test pulses are well defined, to allow for unified testing regardless of which test lab that performs the test. In the real world, however, the disturbances might of course differ from the test pulses since a real case environment is not controlled. \cite{iso_7637_2,iso_16750_2, comparison_iso_7637_real_world}
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-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 thesis.
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+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.
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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.
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-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}.
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+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.
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\todo[Bild med kurvornas parametrar, båda ISO standardernas definitioner]
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\subsection{Test pulse 1}
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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.
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-In the standard there are two additional timing 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 to short to be clearly distinguishable.
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+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.
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\todo[Två bilder, en på kurvan och en på kretsen som orsakar den. En tabell med parametervärden.]
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\subsection{Test pulse 2a}
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-This pulse simulates the event of a load, parallel to the DUT, is 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.
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+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.
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\todo[Två bilder, en på kurvan och en på kretsen som orsakar den. En tabell med parametervärden.]
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\subsection{Test pulse 3a and 3b}
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-Test pulse 3a and 3b simulates transients ``which occur as a result of the switching process'' as stated in \cite{iso_7637_2}. The formulation is not very clear, but is interperted and explained by Frazier and Alles \cite{comparison_iso_7637_real_world} to be the result of a mechanical switch brekaking an inductive load. These transients are very short, compared to the other pulses, and the repetition time is very short. The pulses are sent in bursts, grouping a number of pulses together and separating groups by a fixed time.
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+Test pulse 3a and 3b simulates transients ``which occur as a result of the switching process'' as stated in the standard \cite{iso_7637_2}. The formulation is not very clear, but is interperted and explained by Frazier and Alles \cite{comparison_iso_7637_real_world} to be the result of a mechanical switch breaking an inductive load. These transients are very short, compared to the other pulses, and the repetition time is very short. The pulses are sent in bursts, grouping a number of pulses together and separating groups by a fixed time.
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These pulses contain high frequency components, up to 100~MHz, and special care must be taken when running tests with them as well as when verifying them.
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@@ -71,28 +68,18 @@ These pulses contain high frequency components, up to 100~MHz, and special care
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\subsection{Load dump Test A}
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The Load dump Test A simulates the event of disconnecting a battery that is charged by the vehicles alternator, the current that the alternator is driving will give rise to a long voltage transient.
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-This pulse has the longest duration, $t_d$, of all the test pulses. It also has the lowest internal resistance. These properties makes it capable of transferring high energies into a low impedance DUT.
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+This pulse has the longest duration, $t_d$, of all the test pulses. It also has the lowest internal resistance. These properties makes it capable of transferring high energies into a low impedance DUT or dummy load.
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-Prior to 2011, the Load dump Test A was part of the ISO~7637-2 standard under the name \emph{Test pulse 5a}. The voltages specified for $U_s$ was in the older standard, ISO~7637-2:2004, defined relative to the DC offset voltage $U_A$. In the newer standard ,ISO~16750-2:2012, $U_s$ is defined as the absolute peak voltage including $U_A$.
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+Prior to 2011, the Load dump Test A was part of the ISO~7637-2 standard under the name \emph{Test pulse 5a}. The surge voltage $U_s$ was in the older standard, ISO~7637-2:2004, defined as the voltage between DC offset voltage $U_A$ and the maximum voltage. In the newer standard ,ISO~16750-2:2012, $U_s$ is defined as the absolute peak voltage. Only the former definition is used in this paper, $U_s = \hat{U} - U_A$.
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\todo[Två bilder, en på kurvan och en på kretsen som orsakar den. En tabell med parametervärden.]
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\subsection{Test setup}
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-During a test, the nominal voltage is first applied between the plus and minus terminal of the DUT's power supply input, then a series of test pulses are applied between the same terminals. The pulses are repeated at specified intervals, $t_1$, as depicted in \autoref{fig:doubleexprep}.
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+During a test, the nominal voltage is first applied between the plus and minus terminal of the DUT's power supply input. Then a series of test pulses are applied between the same terminals. The pulses are repeated at specified intervals, $t_1$, as depicted in \autoref{fig:doubleexprep}.
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\todo[Snygg bild på uppkoppling och kopplingsnätverk.].
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-\subsection{Mathematical description}
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-All of the test pulses applied to the vehicle equipment can individually be described mathematically by variations of the double exponential function shown in \autoref{eq:doubleexp} and \autoref{fig:doubleexp}. The properties of interest, the ones which are specified in the standards, are the surge voltage $ U_s $, the rise time $ t_r $, the duration $ t_d $ and the repetition time $ t_1 $. \cite{iso_7637_2}
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-
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-How $k$, $\alpha$ and $beta$ are related to these properties will be described in more detail in \autoref{sec:double_exponential_function}.
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-
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\todo[Tryck ihop bilderna och gör dem lite mindre]
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-\begin{equation}
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- u(t)=k(e^{\alpha t} - e^{\beta t}) + U_{A}
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- \label{eq:doubleexp}
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-\end{equation}
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-
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\begin{figure}
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\includegraphics[width=\textwidth]{doubleexpfunc}
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\caption{The rise time is defined as the time elapsed from 0.1 to 0.9 times the maximum voltage on the rising edge of the function. The duration is defined as the time from 0.1 times the maximum voltage on the rising edge, back to the same level of the falling edge.}
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@@ -273,6 +260,14 @@ Relays, isolation, dielectric strength
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\section{Analysis}
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The data points from the measurement must be processed and evaluated to determine if the measured pulse is within the specified limits. There are several techniques to accomplish this, which have different advantages.\cite{source}
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+\subsection{Mathematical description}
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+All of the test pulses applied to the vehicle equipment can individually be described mathematically by variations of the double exponential function shown in \autoref{eq:doubleexp} and \autoref{fig:doubleexp}. The properties of interest, the ones which are specified in the standards, are the surge voltage $ U_s $, the rise time $ t_r $, the duration $ t_d $ and the repetition time $ t_1 $. \cite{iso_7637_2}
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+
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+\begin{equation}
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+ u(t)=k(e^{\alpha t} - e^{\beta t}) + U_{A}
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+ \label{eq:doubleexp}
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+\end{equation}
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+
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\subsection{Goodness??}
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\label{sec:goodness}
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\todo[Någonting om vad som anses bra]
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Jonatan Gezelius