PAC1 Flashcards
Sampled analogue electric signal
Type of signal that can take any magnitude but is only defined by discrete time instants
Causal system
The output depends only on present and past inputs, this creates a delay
The accuracy of a system does not depend on its own calibration (T,F )
F
The main drawback of an open loop automatic system is its instability (T,F)
F
In a closed loop automatic control system, the controller is the element in charge of information output (T,F)
F
In a system with negative feedback the controller determines the signal necessary in charge to act upon the process in order to invert its dynamics (T,F)
T
Electric sensor
Device able to turn a physical magnitude into an electric signal
Electric sensor ideal features (2)
- Low energetic disturbance of the environment to be measured.
- Proportional relation between the physical magnitud and the electric signal
Cycloconverter
Transforms AC input into AC output
What does a periodic effective value indicate ?
Is equivalent to a continuous signal, it produces the same calorific energy in a resistance
The precision of an open loop control system does not depend on its calibration (T,F)
F
In an open loop control system the disturbances presence stop it to achieve the assigned function (T,F)
T
In a system with negative feedback the controller determines the signal required for the process while not inverting its dynamics.
F
A system with negative feedback allows the action on a physical variable for making its value and the desired equal, it is independent from disturbances (T,F)
T
Types of uncertainties of an electronic system
1) Instrumental: the measuring action with an instrument implies an interaction with the system itself.
2) Intrinsic: for describing the state of a system is needed infinite information
In a converter AC - AC relevant characteristics of regulation
- harmonic distortion: it is a measure moved away from the output wave form respect the other with sinusoidal form.
- potential factor (FP): relation between active (P) and apparent (S) power, gives a measure of the capacity of a load to absorb active power.
The AC mean value is nule (T,F)
T
The mean value of AC with 2V of offset is nule (T,F)
F
An square AC signal with 2V peak value and also a 2V offset has a maximum value of 3V (T,F)
F
For a signal v(t)=28,28sin(100pit), its effective value is 20V (T,F)
T
Inestable system
Has inputs that leads the system to divergent outputs
The principal drawback of an open loop automatic control system is the instability problems (T,F)
F
An open loop control system is strong in face of perturbances if the system is well calibrated (T,F)
F
A system with negative feedback acts on the process to invert its dynamics (T,F)
T
A system with negative feedback is strong in face of perturbances (T,F)
T
Accuracy
Instrument capacity for giving measures near the real value
Precision
The grade where the measurements done in same conditions give the same value
Resolution
Thee minimum increment of an input that can change the output
What have in common the thermionic effect and a p-n semiconductor
There is current only in anode-cathode direction if it is applied a previous polarization
Ideal characteristics of a ecstatic converter wave form
- regulation: robust to load and line perturbances
- harmonic distortion: ideal equal to 0
- power factor: ideal equal to 1
Electric signal
Alteration in the value of an electrical magnitude (potential or current) which is used to represent and transmit information
Noise
Detected signal that does not carry any useful information
Interference
Noise of another communication channel
What indicates the effective value of a periodic signal
Indicates the average power that the signal delivers
Equivalent of effective value
constant DC value that would spend the same thermal power on a resistor
The accuracy of an open loop depends on its own calibration (T,F)
T
In an open loop the presence of disturbances in the chain does not prevent it from accomplishing its assigned function (T,F)
F
In a closed loop the controller is the one in charge of operating on the process in order to follow the set point (T,F)
T
The main drawback of a closed system is its connectivity problems (T,F)
F
Advantages of electronic measurement systems use
- nature of matter: any physical magnitude change can be detected as electrical properties change
- easy amplified, transmitted and stored
- high amplifications allow detectors to be very small
- miniaturization allows less intrusive measurements (terms of energy taken from the system)
Objectives of signal processing system
Dealing with the maximum amount of information using the minimal amount of resources (including time)
Objectives of an energy processing system
Converts one form of electric energy into another according to our needs with the maximal efficiency (minimal loss)
Conversion of an inverter converter
DC - AC
Time invariant sysyem
Behavior and characteristics do not change in time.
A capacitor is time invariant (T,F)
T
The accuracy of an open loop relies only upon its own calibration (T,F)
T
An open loop is robust against the precense of external disturbances (T,F)
F
A system with positive feedback acts upon a process without reverting its dynamics (T,F)
T
A system with negative feedback is robust against the presence of external and internal disturbances (T,F)
T
Sensor
Device that converts value of any physical magnitude into an electrical signal
Role of a sensor in a negative feedback system
Detect the state of the controlled system which allows for the feedback control to revert the deviation with respect the expected value
Why is essential in the field of electronic components the use of semiconductor materials
We can control the electrical conductivity of these materials by acting upon their inner structure and by applying different electric potentials to them
Rectifier converts
AC - DC
Types of full wave rectifier circuits and differences
- rectifying bridge: four diodes, two diodes with a central tap at the secondary winding of the input transformer
- transformer: has electric isolation between input and output, has two diodes that must withstand two times the reverse voltage than the bridge’s diodes for the same output voltage
Closed loop system characteristics
- brings back the output to the input through feedback process
compares the output with the set point value in order to modify the response of a system according to their difference
Semiconductor type N
Semiconductor crystal to which atoms (doping impurities) have been added
- with 5 electrons in the valence (bonds) band
- silicon impurities are usually phosphorous
- when atoms form bonds with silicon the unpaired electrons can produce current through the semiconductor using little energy
Positive feedback
- increases the difference between the output and the reference point value
- used for the design of comparators and oscillators
Negative feedback
- reduces the difference between the output and the reference value
- used for regulation of systems
Analysis
Development of procedures for obtaining a determinate output signal
Synthesis
Choice of components interconnection and set of values for obtaining a particular behavior
Causality
The output only depends on present and past inputs
-implies a delay
Stability
Small inputs lead to outputs that dont diverge
Analogue signal
Continuous values of time and magnitude
Sampled signal
Continuous magnitude values with discrete time values
Digital signal
Discrete time and magnitude values
Transducer
Turns energy from a physical magnitude to another
Modulator sensors
Need an auxiliary energy supply
Generator sensors
The energy needed is supplied by the process itself
Range
Difference between the highest and the lowest limits of a measurement
Ideal electric sensor features
- Low energetic disturbance of environment
- Proportional relation between physical magnitude and electric signal
Chopper conversion
- DC - DC
Rectifier conversion
AC - DC
Inverter conversion
DC - AC
Cycloconverter conversion
AC - AC
Passive component
Absorbs energy
Active component
Delivers energy
P semiconductor
Majority charge carriers are holes in the valence band (Boron)
N semiconductors
Majority charge carriers are electrons in the conduction band (phosphorous)
Requirements for a rectifier diode
- low forward voltage drop
- high reverse breakdown voltage
- low reverse current (leakage)
Zener diode characteristics
- behaves like a normal diode when forward biasing
- conducts in reverse biasing when voltage reaches breakdown (zener voltage)
- limited current
- overpower risk = easy to burn
Zener voltage
Breakdown voltage value, the zener diode starts to conduct in reverse biasing
