1. DC-to-AC Converters Week 10

2. Generic five-level inverter

3. Half-bridge voltage-source inverter

4. Three-level neutral-clamped inverter

5. Advantages of multilevel inverters over the two-level inverters
Synthesis of higher voltage levels using power devices of lower voltage ratings
Increased number of voltage levels which leads to better voltage waveforms and reduced Total Harmonic Distortion (THD) in voltage
Reduced switching stresses on the devices

6. Neutral clamped inverter topology for 3-level inversion+
S11
S21
S31 C1
S12
S22
S32
Vdc o A B C
3-ph
Ac mains C2
S13
S23
S33 _
S14
S24
S34
The neutral point fluctuates as the capacitors C1 and C2 carry load currents
Bulkier capacitors are needed to check the neutral point fluctuation
PWM strategies aim to balance the neutral point dynamically

7. Voltage space vectors of a three-level neutral-clamped inverter

8. STATES, SWITCHING VARIABLES, AND WAVEFORMS OF OUTPUT VOLTAGE IN A THREE-LEVEL NEUTRAL-CLAMPED INVERTER IN THE SQUARE-WAVE MODE

9. Waveforms of output voltage and current in a three-level neutral-clamped inverter in the square-wave mode

10. One phase of a multilevel cascaded H-bridge inverter

11. Switched network for illustration of the operating principle of a resonant dc link

12. Waveforms of voltage and current in the resonant dc link

13. Three-phase resonant dc link inverter with an active clamp

14. WAVEFORMS OF LINE-TO-LINE OUTPUT VOLTAGES IN A RESONANT DC-LINK INVERTER

15. AUXILIARY RESONANT COMMUTATED POLE INVERTER: (A) ONE PHASE WITH THE AUXILIARY CIRCUIT, (B) THE ENTIRE INVERTER

16. IDEALIZED LINE-TO-NEUTRAL VOLTAGE AND LINE CURRENT WAVEFORMS IN A VSI IN THE SQUARE-WAVE MODE

17. BLOCK DIAGRAM OF A PHOTOVOLTAIC UTILITY INTERFACE

18. BLOCK DIAGRAM OF AN ACTIVE POWER FILTER

19. WAVEFORMS OF VOLTAGE AND CURRENT IN AN ACTIVE POWER FILTER

20. UPS SYSTEM

21. BLOCK DIAGRAM OF AN AC DRIVE SYSTEM WITH SCALAR SPEED CONTROL

22. USE OF THE MODULAR FREQUENCY CHANGER OF FIGURE 2
USE OF THE MODULAR FREQUENCY CHANGER OF FIGURE 2.24 IN AN AC DRIVE: (A) SYSTEM WITH A BRAKING RESISTOR, (B) SYSTEM WITH A STEP-UP CHOPPER

23. PWM RECTIFIER-INVERTER CASCADES FOR BIDIRECTIONAL POWER FLOW IN AC MOTOR DRIVES: (A) CURRENT-TYPE RECTIFIER, INDUCTIVE DC LINK, AND CURRENT-SOURCE INVERTER, (B) VOLTAGE-TYPE-RECTIFIER, CAPACITIVE DC LINK, AND VOLTAGE-SOURCE INVERTER

24. SWITCHING PATTERN OF THE INVERTER IN EXAMPLE 7.2

25. PER-UNIT VOLTAGE VECTORS OF THE THREE-LEVEL INVERTER IN EXAMPLE 7.3