PFC boost converter in Typhoon HIL

Question

Hello everyone,
I am currently trying to design a single-phase PFC (Power Factor Correction) boost converter in Typhoon HIL. Although the model runs without any compilation errors, the control system does not seem to be working properly.


Problem description: Although the PWM modulator is supplying an active switching signal to the MOSFET (verified on the scope), the output voltage (V_out) does not rise to the setpoint of 400V. It remains at approx. 325V, which corresponds to the peak value of the mains voltage. Furthermore, the input current (I_in) exhibits the typical peaks of a passive rectifier and does not follow the desired sinusoidal waveform.Model details:Topology: Single-phase bridge rectifier with a downstream boost inductor (L = 2\mH), MOSFET and diode.Load/buffer: C = 470mF  R_load = 200Ω.

Control: Cascaded structure. The outer voltage regulator (PI) sets the amplitude; the inner current regulator (PI) compares the target sine wave with the measured inductor current. PWM: Carrier frequency 20kHz, reference signal range [0, 1].

What I have already checked:

The PWM modulator is linked to the MOSFET via the PWM_Modulator1.TOP_1 signal (core signal). The signal limits (saturation) of the PI controllers are set to [0, 1] for the duty cycle. The hardware parameters (L and C) appear to be reasonable.

Nevertheless, it appears as though the boost effect is not occurring physically, or the PI controllers are outputting a duty cycle that is far too low. Does anyone have experience with tuning PFC controllers in Typhoon, or can you spot a classic error in the wiring of the multiplier chain for reference current calculation? Attached are screenshots of my schematic and the scope waveforms.

Many thanks for your help!

Answer 1

Hi Mamadou,

I don't see any screenshots in your post.

Theoretically, there are two distinct segments of your model: Circuit and closed loop control. My advice would always be to try to run in open loop to make sure your circuit operates as expected - before closing the control loops. In case of boost PFC, you can do that by just feedforwarding the grid voltage to boost modulator.

One thing that you might want to make sure is to follow the guide from documentation on this link: https://www.typhoon-hil.com/documentation/typhoon-hil-software-manual/References/single-phase_diode_rectifier.html#:~:text=The%20default%20state,of%20the%20simulation.

Make sure to disable that optimization.

You can also consider using TyphoonSim to develop the controls, as that simplifies the circuit modeling.

Comments

Hello, thank you for the feedback. I followed your advice and disabled the rectifier optimization (both 'square AC' and 'rectifier optimization' in the experimental tab), but unfortunately, I still cannot get a stable 400V DC output.

I also tried an open-loop test with a constant duty cycle of 0.3, but the voltage still stays at the peak of the grid (~325V) and doesn't boost. It seems like the MOSFET is not switching or the PWM signal is not reaching the gate correctly.

I tried to upload screenshots of my schematic and the scope, but the upload failed. I am using a cascaded control loop (PI for voltage and PI for current) with a 20kHz carrier. Has anyone seen this behavior where the boost effect simply doesn't kick in despite the PWM being active?

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You should be able to confirm whether the PWM signals arrive by looking at the inductor voltage. Does it have a quasi-square wave shape that is expected?