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Abstract: This paper presents a discrete time simulation procedure of switched mode power supply (SWPS) power stages using Euler's forward method for numerical integration. Usually, the simulation of SMPS power stages is carried out in PSPICE alike circuit simulators, but sometimes this is inconvenient and slow. The proposed simulation method may be used for educational purposes, whenever a quick and easy illustration of the SMPSs is desired. Furthermore, it can be deployed in the development of digital control algorithm, as the method may be implemented in logic simulators (event driven or delta time simulators). This discrete time modeling procedure can be implemented in any number crunching environment (Matlab, Octave, NumPy, etc.), in a logic (event-driven) simulator or in a simple spreadsheet. The procedure consists in (i) writing the ordinary differential equations (ODEs) of the modelled power stage, (ii) solving the ODE using numerical methods. Several power stage models were developed and simulated: (i) an ideal buck-boost was simulated in MATLAB, (ii) a boost converter simulated in a spreadsheet and (iii) an ideal synchronous buck converter was described in a hardware description language, VHDL. The numerical error between discrete time and PSCIPE simulation results are negligible.
Keywords: Ordinary differential equations, Logic simulation, Switching converters, Euler's Method, VHDL.
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I.INTRODUCTION
The paper presents a discrete time simulation procedure of several switched mode power supply (SWPS) power stages. Usually, the power stages [1-2] are simulated in Spice like electrical circuit simulators. Spice simulations are completely legitimate, whenever the effects of the switching components (power diodes, MOSFETs, etc.) and other circuit nonidealities (equivalent serial resistance, parasitic components, inductor code magnetism) are sought to be analyzed [3]. A designer can obtain very accurate results in Spice, for the expense of simulation time. Nevertheless, Spice simulation remains just a simulation, there is no guarantee it will work the same in practice. Also, numerical convergence of the Spice solver is easily jeopardized, especially when SPMPs are simulated with ideal switches. Moreover, Spice simulations can be misleading: as the electrical ground is modelled with a 0 V voltage source, and it can inject charges in the simulated circuit - this can result in corrupted waveforms when simulating switching circuits.
In some situations, there is no need for high...