Line-Interactive UPS Topology With Shared Switching Leg Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing uninterruptible power supplies (UPSs) face inefficiencies due to double-conversion of input power, which affects their cost and size, and they struggle to maintain consistent output voltage under varying input conditions.
Innovation Solution
A power-conditioning system incorporating a power-factor-correction circuit (PFC) and a series-active-filter inverter, with a capacitor coupled in series with the load output, allowing for control of switching legs based on modulation indices to regulate output AC voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If double-conversion of input power is used in existing UPSs, then output power regulation is achieved, but system efficiency decreases and cost increases
Solution Approach 1:
The patent divides the power conversion system into separate functional modules: a PFC circuit with first and second switching legs, and an inverter with second and third switching legs. The second switching leg is shared between PFC and inverter functions. This segmentation allows independent optimization of each function while reducing overall complexity and energy loss compared to complete double-conversion architectures.
Solution Approach 2:
The second switching leg serves dual purposes: it functions as part of the PFC circuit during power factor correction operation and as part of the inverter circuit during inversion operation. This multi-functionality eliminates the need for separate dedicated circuits, reducing component count, cost, and energy losses associated with multiple complete conversion stages.
2Reliability
If double-conversion topology is implemented, then output voltage regulation is maintained, but device size and cost increase
Solution Approach 1:
The patent merges the PFC and inverter circuits by sharing the second switching leg and associated components. This consolidation reduces the total number of switching legs from four (in traditional double-conversion) to three, directly reducing device size, component count, and cost while maintaining output voltage regulation capability through coordinated control of the shared leg.
3Reliability
If switching legs are controlled based on modulation indices, then output AC voltage is regulated, but control complexity increases
Solution Approach 1:
The controller receives feedback about the actual output AC voltage and adjusts the modulation indices for the switching legs accordingly. This closed-loop control ensures accurate voltage regulation while using standard PWM techniques, keeping the control complexity manageable through well-established control methods rather than requiring complex open-loop schemes.
Data Source
AI summary
Examples of the disclosure include a power-conditioning system comprising a load output configured to be coupled to a load, a power-factor-correction circuit (PFC) comprising a first switching leg and a second switching leg, wherein the first switching leg and the second switching leg are configured to be controlled based on a first modulation index, an inverter comprising the second switching leg and a third switching leg, wherein the third switching leg is configured to be controlled based on a second modulation index, and a capacitor coupled to an inverter output of the inverter and being coupled in series with the load output.