Multi-Input Power Converter for UPS with Shared Bridge Arms
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Solution Overview
Problem
Existing uninterruptible power supplies (UPS) cannot simultaneously supply power from both AC mains and a rechargeable battery to a load, limiting their applicability and functional expansibility, and they are costly due to the need for redundant power conversion components.
Innovation Solution
A multi-input power converter with n bridge arms connected in parallel between a positive and negative DC bus, a capacitor assembly, an AC switch assembly, and a DC switch assembly, allowing bidirectional energy flow and soft power switching, while reducing component costs through optimized operation modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional uninterruptible power supply uses separate rectifying circuit and bidirectional DC-DC converter, then bidirectional energy flow and soft power switching are achieved, but the sum of power ratings of components is twice the output power, increasing costs
Solution Approach 1:
The patent merges the rectifying circuit and bidirectional DC-DC converter into a single multi-input power converter with n bridge arms. The bridge arms are shared among multiple input sources (AC mains, battery, load), allowing the same components to perform both rectification and bidirectional power conversion functions simultaneously, thereby reducing the total component power rating from twice the output power to 1.5 times the output power.
Solution Approach 2:
Each bridge arm in the power converter is designed to serve multiple functions: it can operate as a rectifier when AC mains are available, as a battery charger/discharger when battery is involved, and as part of the power conversion path for load supply. This multi-functionality allows a single set of components to handle bidirectional energy flow without requiring separate dedicated circuits for each function.
2Reliability
If AC mains and rechargeable battery are used as separate power sources, then power supply reliability is improved, but simultaneous power supply to load is not achieved, limiting functional expansibility
Solution Approach 1:
The patent implements dynamic control of the bridge arms through pulse width modulation (PWM) techniques, allowing the system to flexibly switch between different operating modes (AC mains power supply, battery power supply, simultaneous power supply, regenerative braking) based on real-time conditions. This dynamic operation enables the system to simultaneously accept power from AC mains and battery while supplying to load, achieving both reliability and functional versatility.
Solution Approach 2:
The system dynamically adjusts the duty cycle parameters of the bridge arm switches to control power flow distribution. By changing the switching parameters, the system can regulate the proportion of power coming from AC mains versus battery, enabling simultaneous power supply while maintaining stable output. This parameter control allows seamless transition between different power supply configurations.
Data Source
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AI summary
The present invention provides a multi-input power converter, a control method thereof, and an uninterruptible power supply comprising the same. The multi-input power converter comprises: n bridge arms connected in parallel between a positive direct current (DC) bus and a negative DC bus, where n is a positive integer not less than 3; a capacitor assembly connected between the positive DC bus and the negative DC bus; an alternating current (AC) switch assembly connected between input ends of the first bridge arm to the n-1th bridge arm and alternating currents; and a DC switch assembly connected between input ends of the second bridge arm to the nth bridge arm and a positive electrode of a rechargeable battery. The multi-input power converter of the present invention can realize bidirectional flow of energy and soft power switching with low costs.