2.6.2 Hybrid Duty Control Mode

As this is a frequency controlled converter, the control algorithm controls the PWM switching frequency to regulate the output voltage. However, under certain operating conditions, the controller enters a new hybrid duty control mode where the duty cycle is also modulated. In this mode the switching frequency is still the controlled parameter for the voltage loop. The system enters this operating mode when it can no longer adequately regulate the output voltage with frequency control alone. This mode change is initiated when the software evaluates that the output voltage is higher than the desired voltage by a set limit, while operating at the maximum possible operating frequency. The duty can be reduced all the way to 0% if necessary, putting the PWM module into a burst mode.