Hi folks, ive been playing with ltspice simulation and done coorelation with basic lab equipment with some help form the expert on this forum. One result is from ac analysis and another is from transient analysis. Analysis and design of coupled inductors for twophase interleaved dcdc converters. There are two forms of nonlinear inductors available in ltspice. Enter in the search box the desired order code, product or library name. K1 l1 l2 l3 1 the last entry in the k statement is the coupling coefficient, which can vary between 0 and 1, where 1 represents no leaka. Inductors coupled inductors, dual inductors vishays portfolio of lowprofile, highcurrent coupled inductors are aecq200 qualified, vishay automotive grade, lead pbfree, rohscompliant, halogenfree, and vishay green.
Using transformers in ltspiceswitcher cad iii analog. We are now going to look at simulating a transformer based design. Hello, i would like to simulate a common mode choke in ltspice to limit a current impulse. Download pspice for free and get all the cadence pspice models. My design is in need of a coupled inductor that has 4. This would allow you to have an inductor which was a constant vale from zero to x2 amps. Coupled inductor design optimization for fastresponse low. November 8 1993 abstract the nonideal inductor exhibits both resonance and nonlinear current characteristics. Using a discrete inductor to simulate the leakage inductance is no faster. The software is provided free by linear technology at this web address.
Coupled inductor design optimization for fastresponse lowvoltage dcdc converters jieli li c. Step 2 right click on lp and l2s to open inductor properties window. However, permission to reprint or republish this material for advertising or promotional purposes or. Coupled inductors model online documentation for altium. How do i set an initial current through an inductor. However, should you wish to place individual inductors in the schematic design and couple them, the required information for the spice netlist can be readily supplied through the use of a text frame.
Analysis of circuits with mutually coupled inductor. Similar coupled inductor concepts have been extended to interleaved pwm inverter switching 14, 15. I would think there would be an inductor type component somewhere in ltspice which has dialog entries for inductance at current zero amps, then inductance at current x2 amps, then inductance at current x3 amps. The inductors current is referred to by the keyword x in the expression. Rser0 for each individual inductor, so very good help. The case for coupled inductor in multiphase buck converters whitepaper page 9 121608 an company 4. Analysis and design of coupled inductors for twophase. Spice model of coupled inductor electrical engineering.
Coupled inductors from power distribution across large distances to radio transmissions, coupled inductors are used extensively in electrical applications. How do i define a voltage or currentdependent inductor in ltspice. Find the perfect coupled inductor for sepic, zeta, or other applications. Ltspice insists in showing a negative current which contradicts the sense of the one through l2.
This powerful tool can help you avoid assembling circuits which have very little hope of operating in practice through prior computer simulation. How to create a transformer using ltspice transformers that are used here simply steps up or down ac voltages. Using the inductor coupling symbols the new inductor coupling symbols may be used to couple up to six independent inductors on a schematic. I think my problem is how to define the nonlinear inductor in lt spice, i can not find any example from the website, some are just part of the model, so i do not know how to put them in my model, sorry for not understanding lt spice. Ltspice simulating the switching of an inductor all. What is the difference between a coupled inductor and an. Inductors coupled inductors, dual inductors vishay. Modeling nonideal inductors in spice martin ohara technical manager, newport components, u. Plot the specifications, l vs i, and core losses of up to 6 inductors on the same graphs.
Around the spice kernel lot of people have programmed shells and programs for simple and intuitive usage. Inductors in parallel and parallel inductor circuits. Hello, anybody know how to do a saturable inductor in ltspice. Their properties allow for increasing or decreasing voltage and current, transferring impedance through a circuit, and they can isolate two circuits from each other electrically. Using transformers transformers and coupled inductors are key components in many switching regulator designs to include flyback, forward and sepic converters. Hc coercive force, br remnant flux density, and bs saturation flux density, and the mechanical dimensions of the core. Sullivan found in ieee applied power electronics conference, mar. Placing a transformer with a coupled inductor model is probably the simplest and quickest way of adding a coupled inductor to your source schematic. I understand that the emitter current q2, at the moment it is turned on, should be positive starting from 0 ma. Model libraries for linear technology ltspice switchercad. You model a coupled inductor in spice and other simulators by using a component called k. Ltspice design center analog devices linear technology. Model libraries for linear technology switchercad iii.
One is a behavioral inductance specified with an expression for the flux. Transformers are a key component in many switching regulator designs, providing an isolation barrier in dangerous high power systems, allowing very high stepdown or stepup ratios in high voltage designs and with an extra winding easily accommodating multiple or inverting outputs. Lt spice, leakage inductance showing 1228 of 228 messages. Ltspice is a high performance spice simulation software, schematic capture and waveform viewer with enhancements and models for easing the simulation of analog circuits. Mutual inductance and transformer circuits with ltspice iv university of evansville july 27, 2009. This missing transformer can be made up of 2 inductors, together with a spice directive coupling the inductors. So when examining the datasheets of coupled inductors which give only parallel and series ratings, i am inclined to think that one must perform handcalculations in order to determine the inductance of each coil. Depending on the inductor series, the advanced spice models may include a variable inductor element, variable series resistance rvar1 to model skin effect, a resistor element in series with the parallel capacitance r1 to limit impedance at resonance, and a variable parallel resistance rvar2 to model frequencydependent low power core losses. Mutual inductance is designated in a spice netlist by beginning the first word label of a new line with the letter k.
Draft an inductor for each transformer winding couple them using a single mutual inductance k statement via a spice directive. Equivalent circuits of mutually coupled inductors as was already mentioned in the second topic, when the magnetic field of one coil reaches a second. Coupled inductors broaden dcdc converter usage introduction recently, inductor manufacturers have begun to release offtheshelf coupled inductors. They perform critical function in providing an isolation barrier, enabling high stepdown or stepup ratios and accommodating multiple or inverting outputs. Then, inductors in parallel have a common voltage across them and in our example below the voltage across. There are three ways to set a current through an inductor. This application note covers the following topics explaining the use of inductor coupling symbols in a capture pspice project. Consisting of two separate inductors wound on the same core, coupled inductors typically come in a package with the same length and width as that of a single inductor of the same inductance value. This paper explains, in depth, how to create spice models for the most important and pervasive element in power electronics, that of the transformer and its accompanying saturable core.
Spice model of a transformer that saturates with a model of an ideal transformer and an inductor that saturates. Power electronics ltspice how to model coupled inductors in smps. Lt spice apparently compiles the netlist into raw x86 machine code. A coupled inductor is actually a pair of inductors. Lt spice and inductors parallel to ac voltage sources. Inductor coupling and magnetic core transmission line coupling. A wide variety of coupled inductor options are available to you, there are 184 suppliers who sells coupled inductor on, mainly located in asia. Model libraries for linear technology switchercad iii switchercad iii is a high performance spice iii simulator that simplifies the design of switching regulators. Writing simple spice netlists introduction spice is used extensively in education and research to simulate analog circuits. In the case of a resistor i simply write r100vvkey, but the simulator refuses to accept l. Inductors are said to be connected together in parallel when both of their terminals are respectively connected to each terminal of another inductor or inductors. Coupled inductors are available at mouser electronics. Rather, it is placed as a line of text spice directive onto the schematic and passes directly to the netlist to be processed by the solver.
Lets assume there is a 10mh inductor with its part attribute defined as l3, and we want to set an initial condition of 1ma across it. By proper selection of the on and off resistances, they can be effectively zero and infinity in comparison to other circuit elements. Transformers and coupled inductors are key components in many switching regulator designs to include flyback, forward and sepic converters. Two windings are coupled when some of the magnetic flux produced by currents flowing in either of the windings passes through both windings. Spicesimulation using ltspice iv reverse engineering. The switch model allows an almost ideal switch to be described in spice. A normal inductor is coupled only to itself that is, it has one input and one output, with voltage and current following the relationship coupled inductors are coupled together that is. Linear technology magazine september 2006 23 design ideas l introduction. A rectified source of 320v 50hz charges a capacitor until it reaches the voltage, at which the spark gap strikes. The switch is not quite ideal, in that the resistance can not change from 0 to infinity, but must always have a finite positive value. Included in the download of ltspice are macromodels for a majority of analog devices switching regulators, amplifiers, as well as a library of devices for general circuit simulati. Mutual inductance and transformer circuits with ltspice iv.