摘要 |
An electric drive apparatus and method for controlling medium-voltage alternating current motors wherein a multi-phase power transformer having multiple secondary windings provides multi-phase power to multiple power cells which provide four quadrant operation. Each power cell has a single-phase output and is controllable by a modulation controller. The power cells are connected in series thus permitting the maximum output voltage for each cell to be less than the maximum line-to-line voltage. Each power cell can have a rectifier portion to convert input AC-to-DC, capacitors, an output DC-to-AC inverter, a regenerative bridge converter connected in parallel with the rectifier portion and a local modulation controller connected to a master controller. |