Highly - Efficient and Modula Medium - Voltage Converters

3 I CONTROL OF THE DC-AC MMC FOR VARIABLE-SPEED DRIVE SYSTEMS 5 1.1 Glossary of terms 5 1.2 Introduction 6 1.3 The MMC 8 1.3.1 Dynamic Model 8 1.4 Low-Frequency Operation 9 1.4.1 The Existing Sine-wave Strategy 9 1.4.2 The Proposed Strategies 11 1.4.3 Comparison of the Proposed Strategies with the Sine-Wave Strategy 12 1.5 Controller Design Methodology 13 1.6 Closed-loop System 15 1.6.1 Closed-loop System Dynamics 15 1.6.2 Stability Analysis of the Closed-loop System 17 1.7 Experimental Results 20 1.7.1 Startup Operation 21 1.7.2 Step Change in Torque 22 1.7.3 Steady-state 24 II CONTROL OF THE DC-DC MMC 26 2.1 Mathematical Modeling ofthe DC MMC 26 2.1.1 Basics of Operation 26 2.1.2 Phasor-domain Steady-state Model 27 2.2 Converter Design and Component Sizing 30 2.2.1 Arm Inductive Reactance 30 2.2.2 Phase Filtering Inductive Reactance 31 2.2.3 SM Capacitive Reactance 32 2.2.4 Operating Frequency 33 2.2.5 Simulation Results 35 2.3 Closed-loop Control of the DC MMC 36 2.3.1 TheMCC 39 2.3.2 ThePCC 40 2.3.3 Simulation Results 41 2.4 Conclusions 45 PUBLICATION UNDER THIS GRANT 47 REFERENCES 48