• Journal of Power Electronics
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• v.1 no.1
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• pp.36-47
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• 2001

The carrier-based space vector pulse width modulation(SVPWM), which is considered as highly simple and efficient PWM technology, can be also used in multilevel inverters. The method was originally designed for the two-level inverter and developed to the diode clamped multilevel inverter structure. however it may be noted that it also cause bad switch utilization in cascaded multilevel inverter. This paper introduces an improved carrier-based SVPWM scheme, which is fully suitable for cascaded multilevel inverter topologies because it can achieve the optimized switch utilization through the redistribution of the triangular carrier waves considering leg voltage redundancies while having the advantages of the conventional carrier-based SVPWM. Using simulation and experimental results, the superior performance of new PWM method is shown.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.12
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• pp.624-631
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• 2003

This paper presents a simple carrier symmetric method for the voltage balance of flying capacitors in FCMLI(flying capacitor multi-level inverter). To achieve the voltage balance of flying capacitors, the utilization of each carrier must be balanced during a half-cycle of the switching period such as PSPWM(Phase-Shifted PWM). However, the CRPWM(Carrier Redistribution PWM) method causes the fluctuation of flying capacitor voltages because the balanced utilization of carriers is not achieved. Moreover, it does not consider that the load current change has an influence on flying capacitor voltages by assuming that the current flows into the load. To overcome the drawbacks of CRPWM, it is modified by the technique that carriers of each band are disposed symmetrically at every fundamental period. Firstly, the CRPWM method is reviewed and the theory on voltage balance of flying capacitors is analyzed. The proposed method is introduced and is verified through the experiment result.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.298-301
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• 2005

The flying capacitor voltage control of the flying capacitor multi-level inverter (FCMLI) is very important for safe operation. The voltage unbalancing of flying capacitors caused serious problems in safety and reliability of system. In the FCMLI, balancing problem of the flying capacitor has its applications limited. The voltage unbalance is occurred by the difference of each capacitors charging and discharging time applied to FCMLI. This paper investigates and analyzes multi-carrier PWM methods to solve capacitor voltage balancing problem. The Phase-Shift PWM (PSPWM) method that is commonly used, The Modified Carrier-Redistribution PWM (MCRPWM) method and The Saw-Tooth-Rotation PWM (STRPWM) method are discussed and compared with respect to switching state, balancing voltage of capacitors and output waveform. These three PWM methods are analyzed by using a flying capacitor three-level inverter and provided result through simulation. Finally, the harmonics about the output voltages of their methods are compared using the harmonic distortion factor (HDF).

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.606-610
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• 2003

This paper presents a simple carrier symmetric method for the voltage balance of flying capacitors in FCMLI(flying capacitor multi-level inverter). To achieve the voltage balance of flying capacitors, the utilization of each carrier must be balanced during a half-cycle of the switching period such as PSPWM(Phase-Shifted PWM). However, the CRPWM(Carrier Redistribution PWM) method causes the fluctuation of flying capacitor voltages because the balanced utilization of carriers is not achieved. Moreover, it does not consider that the load current change has an influence on flying capacitor voltages by assuming that the current flows Into the load. To overcome the drawbacks of CRPWM, it is modified by the technique that carriers of each band are disposed symmetrically at every fundamental period. Firstly, the CRPWN method is reviewed and the theory on voltage balance of flying capacitors is analyzed. The proposed method Is introduced and is verified through the experiment result.