Circuit Simulation Engineering

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Circuit Simulation Closed Loop Bode Plot of a 600kHz Push-Pull Converter

Circuit Simulation Closed Loop Bode Plot of a 600kHz Push-Pull Converter

True Power Research is a power electronics consultant and provider of circuit simulation expertise. The simulation of electronic circuits is also commonly referred to as PSPICE analysis, SPICE modeling, etc.

Purpose of PSPICE Analysis

Electric circuit simulation with SPICE and other simulation tools such as SIMPLIS provides an essential verification tool for the development of electronic power supplies. It should not be used as a primary design tool. The design of a power supply must have its foundation in solid design relationships which SPICE and SIMPLIS cannot properly illuminate. However, SPICE and SIMPLIS find their main usage in performance verification of an existing design and for studying the effects of power supply circuit parameters.

Benefits of Circuit Simulation

Primary benefits of SPICE analysis are found in the pre-prototype design stages to verify a design before committing to hardware. Secondary benefits can be found by comparing bench test data to SPICE or SIMPLIS simulation results. If the results do not reasonably agree, it is a fact that the model does not represent the design as built. In that case, the model is wrong, or the prototype is wrong, or both! In whichever case, simulation can be a very helpful tool to expedite understanding of the problem if not immediately obvious.

Benefits of electric circuit simulation:

  • Paper design verification prior to committing to prototype builds.
  • Design review analysis.
  • Making measurements not physically possible to do on the bench.
  • Making measurements which would be extremely dangerous to do otherwise.
  • Studying effects of circuit parameters.
  • Aids in report generation.
  • Quickly prove novel circuit concepts.
  • Gives the ability to quickly study the effects of circuit changes.
  • Test novel concepts for feasibility, with the ability to make and test rapid changes to the design.

What is SIMPLIS?

SIMPLIS stands for “SIMulation for Piecewise-LInear System” and is primarily intended for the simulation of switching power supplies. Circuit elements are modeled with piecewise linear data. As the simulation progresses, the different combinations of piecewise linear states are recorded as circuit topologies. Each circuit topology represents a linearized circuit, allowing simulation to proceed extremely quickly. Eventually, as the circuit approaches steady state, there are no new topologies and the simulation proceeds even more quickly to the end. This is the transient simulation.

SIMPLIS also allows AC analysis straight from the schematic, without having to derive the small signal averaged model. There are many types of power supply topologies from which the small signal averaged model is extremely difficult or impossible to derive. For many of these power supply topologies, SIMPLIS can compute the Bode plot, where in SPICE getting the Bode plot would be impossible.

Last, but not least, for many types of power supply topologies, SIMPLIS can arrive at the steady state waveforms without having to progress through the entire transient simulation. The following picture was taken using this Periodic Operating Point Analysis:

Critical Waveforms for a 600kHz Push-Pull Converter Generated by the SIMPLIS Periodic Operating Point Analysis

Periodic Operating Point Analysis Waveforms for MOSFET Drain Voltage, Output Voltage Ripple, Inductor Current for a 600kHz Push-Pull Converter.

True Power Research is equipped with SIMPLIS, the most state of the art simulation program available. Furthermore, we are also equipped with the following SPICE type simulation packages: Symetrix, Intusoft ICAPS, LTSPICE, and the original PSPICE.

Power Supply Designs has nearly 20 years of experience with using SPICE or SIMPLIS. We can apply SPICE or SIMPLIS analysis and electric circuit simulation to your designs. Call or email us for help with circuit simulation of power supplies.