Although a common DC bus configuration is not new and took rise along with the DC to AC drive migration in the 1990s, there are increased implementations across many different industries.
The majority of variable speed AC drives make two power conversions in their design. Incoming AC power is rectified to DC and then the DC is inverted into a pulse width modulated 3-phase AC waveform that can control many different types of AC motors. This unitarily adapted and proven design principle has an impediment for many applications.
For example, when the motor needs to stop or change torque direction from motoring to regenerating, the inertia energy needs to be addressed. In a low-inertia or a simple pump application, stopping the motion can be as easy as turning off the AC drive and coasting down or setting a mechanical brake.
For most system-type applications, there are more demanding needs with fast stopping, quick direction changes, and overhauling loads that increase the complexity of the solution.
