I ensured that the open loop current mode converter works properly. Switch current in blue, gate drive voltage in green, output voltage in red, and inductor current in yellow. You can see below some of the steady state waveforms generated using the circuit in 'boost_currentmode_openloop.sxsch'. This ensures that S1 switches properly.Īnd yes I have tested a simple open loop boost converter and it works just fine. E1 is a voltage controlled voltage source that acts as a voltage buffer between the latch and ideal switch, as it has gain set to 1 as seen in the picture. In the circuit and image attachment above named 'boost_currentmode_openloop.sxsch', the turn-on threshold is set to 2V, while the S-R latch U2 outputs a low voltage of 0V, and a high voltage of 5V. It has parameters such as off resistance, saturation resistance, and a turn-on voltage threshold that you can easily change (see picture below). It's basically a voltage controlled ideal switch. Here are the simulations files for reference: I have been stuck with this problem for the past week :-( still no progress.Ĭould anyone point mo to the right direction? What am I doing wrong? Is my understanding of CM, based on the circuits, flawed? Are there other factors I failed to account for? Any help would be appreciated :grin: I tried to set initial conditions on the inductor and capacitors, but the analysis still won't converge. However, SIMPLIS POP analysis is unable to converge. Now what's left to do was to close the loop - connect the compensator to the converter. The op amp used in this design was the standard LM358.

I confirmed my design by generating the transfer function of my compensator in SIMetrix software. Using the k-factor method of determining the R's and C's of the compensator, I came up with the standard op-amp based implementation. This meant the compensator needed to give a gain of 10dB and phase boost of 45-(-120+90)=75 degrees. From the bode plots, the converter had a gain of -10dB and a phase of about -120 degrees at f=fc.

I wanted a crossover frequency of fc=fs/10=10khz and a phase margin of 45 degrees. From these plots, I designed a type II compensator. I started off my attempt to close the loop by generating a control-to-output bode plot using SIMPLIS's AC analysis. To have a solid understanding of CM, I used primitive components available in SIMPLIS such as discrete comparators, controlled sources, an S-R latch and a parameterised op amp.

Here are the converter specs I followed: Vi = 12V, Vo=18V, Io=1A, fs=100khz. However, I am having convergence issues with the simulator. I've been trying to implement a compensated closed-loop current mode(CM) controlled boost converter using the SIMPLIS engine.

Simplis pop