Introduction to Digital Power Conversion
XMC4000/1000 Family
PWM Generation
Application Guide 41 V1.0, 2015-01
4.13 Half-Bridge LLC Control using ½ CCU4
LLC Converter Power Transfer by Pulse Frequency Modulation Control (PFM)
The power transfer through an LLC converter can be controlled by frequency and/or PWM. The
operating point should focus on the inductive property slope of the gain-vs-frequency characteristic
curve, where the current phase is delayed and the gain will be reduced by increasing the frequency.
LLC Converter using a pair of Inter-connected CCU4 Slices in Single-Shot Mode
Figure 30 Half-Bridge LLC Converter – Using CCU4
50% duty-cycle and center aligned modulation (referenced to the sinusoidal voltage zero-crossings)
can be achieved by two timer-cells in equal single-shot mode, interacting by alternately starting each
other.
PWM tuning may be added onto the invoked dead-times and be controlled by the compare registers.
Note: This configuration can also be made by a single CC8y slice timer (See Figure 32).
LLC Converter Power Transfer by PWM Fine-Tuning Control
PWM duty-cycle also impacts on the power transfer through an LLC converter, since the amount of
energy is cycle wise injected into the resonant tank. This enables output level fine-tuning.
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