Hybrid control topology for regenerative cascaded h-bridge circuitry

Abstract

Disclosed is a system with regenerative cascaded H-bridge circuitry leveraging a hybrid control topology, an example of which is a variable frequency drive. Hybrid control allows for substantially cost and efficiency-improved implementation. With hybrid control, fault detection and gating control are split into those features managed at an regenerative power cell level (e.g., fundamental front-end control), those features managed at a central controller level (e.g., alternating-current over/under voltage detection), and those features that may be collaboratively managed by both the regenerative power cell and controller control (e.g., phase synchronization, direct-current bus over/under voltage detection, and power loss). Hybrid control uses current sensors at the input to the primary coil of a transformer in the system and voltage sensing at each regenerative power cell of the system. Voltage sensing at each regenerative power cell eliminates the need to calibrate the transformer during commissioning, while fewer current sensors improve implementation cost.