Half-bridge inverter DC supply requirement A single-phase half-bridge inverter uses two main switches and a DC midpoint. Which statement best describes its DC supply requirement?

Introduction / Context:
The single-phase half-bridge inverter produces a bipolar output by referencing each leg alternately to the mid-point of the DC link. Understanding its DC requirement (true three-wire supply or two-wire formed into three-wire via split capacitors) is fundamental in power electronics design.

Given Data / Assumptions:

• Topology: half-bridge with two active switches.
• Midpoint is required to generate +Vdc/2 and −Vdc/2 levels.
• Midpoint can be provided by a real three-wire source or by two series DC capacitors (virtual three-wire).

Concept / Approach:

A half-bridge inherently requires a central reference (midpoint) to create two equal and opposite voltages across the load. Even if the DC bus is originally two-wire, designers split it with two series electrolytics to create a neutral, still functioning as a three-wire DC supply. Thus, the accurate statement is that a three-wire supply (real or synthesized) is needed.

Step-by-Step Solution:

Verification / Alternative check:

Datasheets/application notes show half-bridge DC link drawn with two capacitors in series and their junction as the neutral node.

Why Other Options Are Wrong:

Stating “two-wire” alone omits the need for a midpoint; claims about higher voltage/efficiency are secondary and not inherent to needing three wires.

Common Pitfalls:

Confusing half-bridge (needs midpoint) with full-bridge (does not need midpoint).

Final Answer:

needs a 3 wire dc supply