In this case, the current out of the source will be adjusted depending on the voltage across the load so that a constant power is generated. The simulated electrochemical cell or stack behaviors through suitable physical elements in the equivalent circuit are potentially matched with the realworld reactions. Arduino programmable constant current power resistance dummy load. Adjustable constant current load circuit wiring diagrams.
Usually charging resistance rs is chosen to limit the charging current to about 50 to 100 ma while the generator capacitance c is chosen such that the product cr s is about to 10s to 1 minute. For this application a lightemitting diode led is shown as the load, in which the constant current. It is likely that the old url for this pspice tutorial will disappear on august 31, 2015. Circuit elements and models university of california, berkeley. Verify your hand calculations and homework in circuits 1 and circuits 2 class. The tutorial starts under the assumption that the demo version of pspice is installed on your computer. From figure 1b, the load current is equal to the driver current, i. Ltspice demo circuits design center analog devices. Pspice tutorial dc transient simulation charging a. So far we have covered circuits with resistors and independent sources. Pspice student is sometimes distributed under different names, such as pspice. Dec 09, 2019 for the love of physics walter lewin may 16, 2011 duration. The circuit is a current mode buck converter that was derived by christophe basso. It is this inverse property of a constant power load that is often useful in stability analysis of simulations like those of a switching mode power supply.
And pspice is a product of the orcad corporation and the student version we are using is. My basic understanding of this kind of circuit is that for variations of input voltage, say between 20v and 30v the current sink should remain constant. At the start of the tutorial a brief introduction of ac alternating current is provided after that a simple ac circuit is implemented in pspice. Constant current, constant power and constant impedance.
Apr 14, 2009 ive come up with a couple of very easy ways to create constant power loads in ltspice. We wish to warn you that since pspice files are downloaded from an. I os where i b and i os are, respectively, the input bias current and the input offset current specified by the opamp manufacturer. Ltspice is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits. For instance, a constant current load dynamically adjusts its resistance as the load voltage varies, such that the load current remains constant, i vr. For the love of physics walter lewin may 16, 2011 duration. This supply would receive a regulated 48volt input and was required to generate a user adjustable constant current output in the range between 3 and 8 amps.
Although the battery voltage is indicated as 5v, pspice will let us vary this experimentally over any required range. This load will allow you to draw a set current from any source. Atmel applications journal atmel avrbased constant. Simulate adaptive switching regulators using pspice.
An lpad is used to change speaker output level whilst maintaining a constant impedance load to the amplifier. A constant power load is designed to dynamically adjust the load current inversely with the load voltage so that the load power is constant, p vi. Spice is a program developed by the ee department at the university of california. I have a circuit where i want to have a constant current of 2ma through a variable resistor.
Pdf simulation of a current source with a colecole load. Learn the basics of circuit simulation using cadence design systems powerful simulation software. It was the first time i heard and work with the pspice software. One is a resistor whose resistance is a function of the voltage across it, and the other is a voltagedependent current source using a piecewise. The resulting input exponential waveform and inductor. Pspice engine through a simple example a diode recti. The circuit below shows the use of the constant power load macro. Pspice download free software and games free download. A current source in pcb design is usually derived from transistors. The results showed that the constant and high output impedance current sources for multifrequency could be fulfilled both eh and toa current sources prepared with opamp ad844 and a colecole load. Also pspice is a simulation program that models the behavior of a circuit. The simulation can be a time domain transient, a dc sweep, or an. Ltspice provides macromodels for most of analog devices switching regulators, linear regulators, amplifiers, as well as a library of devices for general circuit. The circuit is an rf amplifier with 50ohm source and load impedances.
Show step by steps how to load and create the pspice file at csu. Download pspice for free and get all the cadence pspice models. Software to design, analyze and simulate electronic circuits. Public circuits tagged ccconstantcurrent circuitlab. The constantpower load arises when any energy consuming load is equipped with a powerefficient regulator. Throughout this article, ill refer to the output of the current source as bias current or i bias, because i think that the biasing application is a more straightforward vehicle for pondering this circuits basic functionality. Orcad free trialorcad trial provides full version of the latest release of orcad electronic design software solutions for free for a limited time, including orcad capture cis, orcad pspice designer, orcad pcb designer professional, orcad sigrity erc, and more. If we need a graphical output, pspice can transfer its data to the probe program for graphing purposes. In this tutorial, we will examine mosfets using a simple dc circuit and a cmos inverter with dc sweep analysis this tutorial is written with the assumption that you know how to do all of the basic things in pspice. You can put a switch in series to break a voltage but if you put it in series with an ideal current source, the current will still manage to get through the switch even if it is 1g ohm. Robinson never explained in detail how to create and run a circuit in pspice. The constantpower load is an element that occurs frequently as a systemslevel model of the load device connected to a power supply. Pspice tutorial 3 using pspice for circuits with dependent sources the problems in this tutorial and the corresponding homework continue to deal with the dc analysis of circuits, or dc bias analysis in pspice.
Typical with power grid tubes as with eimac, svetlana. Atmel applications journal atmel avrbased constant current. Constant current, constant power and constant impedance loads. The basic concept has been around for a long time though, and its essentially an opamp based current source design. This supply would receive a regulated 48volt input and was required to generate a user adjustable constant current.
For instance, the emitter current of a bjt transistor is defined by the current that flows through the base. Ive been told that i could probably use a lm317 as a current regulator, with one resistor on the ouput. You can put a switch in series to break a voltage but if you put it in series with an ideal current source, the current will still manage to. Constantvoltage, constantcurrent flyback controller. Both are bounded to prevent convergence problems, and they work very well for most applications. To model such a load, we can use a voltage dependent current source. A constant current load source and a resistive load can produce different results, especially in the frequency domain simulations. Input bias current ib and input offset current ios. Such a gadget is useful if you want to measure the capacity of chinese liion. Voltage sources, in addition to being used for circuit excitation, are the ammeters for spice, that is, zero valued voltage sources may be inserted into the circuit for the purpose of measuring current. Arduino programmable constant current power resistance. This reference design is an auxiliary power supply with 24v, 2a output. A source to be tested should be put in place of vtest.
The switch node and inductor current are also shown, along with a close up version. Constant current source using ref for grounded load. Constant power load macro spring 2008 spectrum software. Pspice voltage and current sources watch more videos at videotutorialsindex. Pspice student is sometimes distributed under different names, such as pspice student thinstalled. The values of the ic ib hfe beta of the transistor.
Line impedance including resistance and inductance should be modeled, especially if the leads from the power supply to the test board are more than a few feet. As i have to do the simulation for step change of constant power load to see the result, i cannot use the series load block. As i have to do the simulation for step change of constant power load to see the result, i cannot use the series load. One is a resistor whose resistance is a function of the voltage across it, and the other is a voltagedependent current source using a piecewise linear approximation. A constant power load varies its impedance on change of input voltage to keep the power constant. Constant power load using table in power systems, it is common to encounter loads which draw constant power. Hello everyone, just a video explaining how to reproduce an example simulation from standard pspice learning modules in the orcad trial and the orcad lite 17.
The line and load regulation of the power supply is designed to be within 1% using secondary side regulator ucc28740. In september of 2002, a new client approached controltek requesting design services for a constant current power supply. This tutorial introduces the dependent source elements in pspice. This circuit provides a constant current load through q1 and q2. Ive come up with a couple of very easy ways to create constant power loads in ltspice. The library only for this tool enables simulation of the dc bias characteristics in high dielectric constant type mlccs and the dc superposition characteristics in power inductors, by adopting the dynamic models of muratas high dielectric constant. In order to eliminate the rising portion of the vexp waveform we have set td1, td2 and tc1 equal to 1e9. I os where i b and i os are, respectively, the input bias current and the input offset current. Jun 11, 2019 a current source in pcb design is usually derived from transistors. Pspice schematic with vexp source in this example we want to model a decaying exponential with a time constant of 1 second and an initial value of 1 volt. Commonemitter transfer characterisitic for the npn bjt 0 0. To find the dc conditions for voltage, current, temperature and parameter global of the circuit. Glad to see you have arrived on this page to learn how to build a programmable constant direct current dummy load.
Pspice utilizes the implied 1 and 2 ends for its handling of current. Cadence pspice technology offers more than 33,000 models covering various types of devices that are included in the pspice software. A constant current circuit can also be used as a current. My basic understanding of this kind of circuit is that for variations of input voltage, say between 20v and 30v the current sink should remain constant, fo my application 20ma. Spice tutorial purdue engineering purdue university. Public circuits tagged constantcurrentsource circuitlab.
Constant current dummy load designs built around the venerable lm324 quad opamp have become quite popular in the hobbyist community. Hello, do you know why this constant power load 20w simulation wont work. By providing a positive voltage at the baseemitter junction, a constant current will flow through the emitter which is a direct function of base current. As long as the load is demanding a constant amount of power, raising its input voltage will cause the regulator to lower its current demand, and vice versa. The constant power load macro is the x2 device at the. A constant current load is the one which varies its internal resistance to achieve a constant current regardless of the voltage which is being fed to it within certain extent and therefore the power will vary. I need the resistor to dissipate 20w constantly, throughout the bus voltage excursions. Creating impedances with behavioral modeling pspice. Pspice simulates the circuit, and calculates its electrical characteristics. Dec 14, 2014 i want to build a constant power load in simulink and i use controlled current ipvdc, as shown in figure.
Type the components you required in the part window. Use the link given below and proceed to the developers website in order to download pspice free. Using the free orcad viewer allows you to open a project, schematic, or library and access design data very easily. Education software downloads pspice student by cadence design systems, inc and many more programs are available for instant and free download. As long as the load is demanding a constant amount of power, raising its input voltage will cause the regulator to lower its current. Spice model for a constant power load device the constant power load is an element that occurs frequently as a systemslevel model of the load device connected to a power supply. Use the component vdc for dc power supplies, and vac for signal sources. When you type p you will get at the right side of window. But ive read some places that the lm317 takes minimum 510ma load. The line and load regulation of the power supply is. I have designed various flavours of constant current sink circuits, either by breadboarding or by using orcad and pspice.
Simulation of lightning characteristics using pspice software. The output voltge is very large because of the dclink capacitor. Advanced analysis is an addon program for pspice1 and pspice. The tps6123x is a high current, high efficiency synchronous boost converter with constant output current feature for single cell liion and lipolymer battery powered products, in a wide range of power. Oct 07, 2009 hi all i design this current source no need to mention its stupid desing. A constant current source ccs in electronics is a devicecircuit that produces a constant value of current regardless of source voltage or load resistance. The dc sweep analysis varies a voltage source over a range of. Ib1 and ib2 model the input bias current at each input terminal of the op amp, with. Impulse generator and lightning characteristics simulation. Equivalent circuit elements for pspice simulation of pem. The constant power load arises when any energy consuming load is equipped with a powerefficient regulator. This pwm signal gets smoothed out by an rc filter to produce a smooth analog voltage. Let us now add the load line to the above plot to find the operating point, commonly.
An ac circuit is the one in which the source of the circuit is of alternating current rather than dc direct current. The basic mosfet constantcurrent source technical articles. The rl time constant indicates the amount of time that it takes to conduct 63. Starting from the left, we have a pwm signal that will come from an arduino io pin.
Understand how to use pspice for basic circuit analysis. This download was checked by our antivirus and was rated as virus free. Ltpowercad ii the ltpowercad ii design tool is a complete power supply design tool program that can. In power systems, it is common to encounter loads which draw constant power. This load can also be set to a constant resistance or a constant. A constant impedance load is simply a load that presents an unchanging impedance, like a resistor. In this small project i will show you how to make a simple adjustable constant current load. In the constant power case the voltage times the current of all of the other pairs is your desired load power. Tps61236p 8a valley current synchronous boost converters.
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