POWER ELECTRONICS (BPB23204) TUTORIAL 4 S JANUARY 2021 Question 1 a) With reference to the circuit diagram shown in Figure 1 and the switching pattern in Table 1, sketch and label clearly the equivalent circuits for all intervals (0-60, 60120, 120-180, 180-240, 240-300, 300-360) ̊. b) For the interval 180 – 240 in a), If E = 600V and R = 50Ω (Balance load), evaluate: i. Phase voltages; VAN, VBN and VCN ii. Line voltages; VAB, VBC and VCA iii. Determine power to the load. Table 1 Interval S1 S2 S3 S4 S5 S6 0º to 60º ON OFF OFF OFF ON ON 60º to 120º ON ON OFF OFF OFF ON 120º to ON ON ON OFF OFF OFF OFF ON ON ON OFF OFF OFF OFF ON ON ON OFF OFF OFF OFF ON ON ON 180º 180º to 240º 240º to 300º 300º to 360º c). The operation of the circuit in Figure 1 is change to 120˚ conduction mode with the switching operation as shown in Table 2. i. Draw an equivalent circuit for an interval 180˚ to 240˚ ii. Evaluate the phase voltage VAN, VBN, and VCN for the equivalent circuit in part (i) iii. From the value of phase voltages in (ii), calculate the line voltage, VAB, VBC, and VCA iv. Determine the power delivered to the load in each phase. Figure 1 Table 2 Interval S1 S2 S3 S4 S5 S6 0˚ to 60˚ ON OFF OFF OFF OFF ON 60˚ to 120˚ ON ON OFF OFF OFF OFF 120˚ to OFF ON ON OFF OFF OFF OFF OFF ON ON OFF OFF OFF OFF OFF ON ON OFF OFF OFF OFF OFF ON ON 180˚ 180˚ to 240˚ 240˚ to 300˚ 300˚ to 360˚