Fig. 2 shows a converter topology known as a "semi-bridge", which consists of a high side buck converter and a low side buck converter feeding into a RLC load. The IGBTs of both converters are simultaneously switched with the same high frequency modulation signal, to create a DC output voltage across the load resistor which varies with duty cycle D. 100V + TOYS 13 51 D3 AD2 HK KA $4 1.2 Ribad 100 Figure 2: Semi-Bridge Single Phase Converter The load capacitor C is large enough so that the voltage developed across Road is essentially DC (i.e. the voltage ripple across the resistor is negligible). The two converters are switched at f = 10kHz by comparing the target duty cycle D against a triangular carrier waveform. S.a. Sketch the following waveforms for a duty cycle of converters are operating in continuous conduction mode (CCM): assuming the switched output voltage of each phase leg, the switched voltage that is consequentially developed across the load. the current flowing through L. 5.b. Show that the ripple current in L is given by 2VDC(1-D)D Lfs [7 marks] using a similar linear analysis approach as was used to analyse a single buck converter. [6 marks] 5.c. Determine the modulation duty cycle at which the assumption of CCM becomes invalid for the semi-bridge converter, using a similar approach as was used to identify the discontinuous conduction boundary of a simple buck converter. [6 marks] 5.d. For a duty cycle of 0.5 (when the system is operating in discontinuous conduction), sketch the waveforms of the following: the current flowing through L the switched voltage that is consequentially developed across the load