Just came across @marcos.uniovi’s YouTube tutorial that explains a LinkedIn post using a Modulator and B-source to generate a complementary gate signal with a constant dead time (which maintain the deadtime ratio when the frequency changes). This is especially useful in LLC resonant converters as their output depends on the operating frequency. Here is the YouTube link from Prof. Marcos Alonso; and LinkedIn Post from Roberto Volpini.
Qspice #16: How to Create a Half-Bridge Gate Driver with Adaptive Deadtime
LinkedIn Post from Roberto Volpini
The reason for using the Modulator is that it can provide phase continuity in changing the frequency setpoint, essentially acting as a VCO. However, the same purpose can be achieved with a simple equation using a B-source, as V=sin(2*pi*idt(V(frq),0)), where V(frq) is voltage represent frequency in Hz.
Therefore, I created another version of PFM with adaptive dead time, where:
- Both Frequency and Dead time are externally controlled.
- The Dead time is linear (exact time ratio, not an approximation).
- With native comparator with TTOL to reduce the timestep when the gate signal changes its state.
This is the concept schematic and explanation document for reference
concept.PFM-SymCompl-DeadTime.qsch (15.7 KB)
Pulse Frequency Modulation with Adaptive DeadTime.pdf (462.5 KB)
Custom symbol can download from this Github link, with application example that follow another @marcos.uniovi youtube video for reference.
PFM-SymCompl-DeadTime.qsym
example.LLC-resonant-converter.qsch (18.9 KB)
