In the field of High Voltage Power Conversion, various techniques have been developped to use series-connected switches.
Plain series connection of switches is the first solution and its drawbacks are now well-known (static and dynamic voltage sharing difficulties that require selecting paired switches or using sophisticated control techniques, high dV/dts generated by the synchronous commutation of all the switches, output waveform that does not benefit from the increased number of switches,...)
The "neutral point clamped" technique introduced in the early '80s improves voltage sharing and dV/dts, and gives a three-level output waveform.
More recently a new multilevel topology has been introduced; compared to former techniques, it really solves the problem of voltage sharing and dV/dts, and gives a three-level output waveform with cancellation of the harmonic and the switching frequency.
In this paper, it is shown that this technique can be easily generalized to voltage-source inveter legs with any number of switches, that these inverter legs can operate under any power factor condition (and especially in the rectifier mode as well as in the inverter mode) and that these legs can be used in half-bridge, full-bridge, or three-phase voltage-source inverters.
Experimental results of a 1.5 kV, 20 A, 48 kHz IGBT line-operated rectifier with sinusoidal input current are given.
| Filename: | Unnamed file |
| Filesize: | 852.7 KB |
