PFC Circuit Voltage Balancing in UPS Battery Mode
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Solution Overview
Problem
Existing UPS systems require additional balancing circuits to maintain positive and negative bus voltage balance during battery supply mode, increasing costs and circuit complexity.
Innovation Solution
The method involves using a power factor correction (PFC) circuit to adjust the duration of switching tube conduction states and employ a relay to balance positive and negative bus voltages, reducing the need for an additional balancing circuit by utilizing the PFC circuit to manage voltage balance during battery supply mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an additional balancing circuit is added to maintain positive and negative bus voltage balance, then voltage balance is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the voltage balancing function with the existing PFC circuit by adding a balancing switch that can operate in parallel with the PFC inductor. This integration allows the same circuit structure to perform both power factor correction and voltage balancing functions, eliminating the need for a separate balancing circuit and reducing overall device complexity.
Solution Approach 2:
The PFC circuit is designed to serve multiple functions: power factor correction during normal operation and voltage balancing during battery supply mode. The balancing switch can be controlled to enable the PFC inductor to serve dual purposes, making the circuit universal and reducing the need for dedicated balancing components.
2Reliability
If a balancing circuit is added to maintain bus voltage balance, then voltage balance is improved, but manufacturing cost increases
Solution Approach 1:
By combining the balancing function with the existing PFC circuit components, the patent eliminates the need for separate balancing circuit components. This reduces the total component count and manufacturing cost while maintaining voltage balance capability.
Solution Approach 2:
The system uses its own existing PFC inductor and switching components to perform voltage balancing, rather than requiring external dedicated balancing components. The balancing switch is controlled to utilize the PFC circuit's inherent capabilities for self-balancing, reducing manufacturing costs.
3Device complexity
If the PFC circuit is used for voltage balancing during battery supply mode, then device complexity is reduced, but the switching control complexity increases
Solution Approach 1:
The patent implements a control mechanism that monitors the positive and negative bus voltages and adjusts the balancing switch accordingly. When the voltage difference exceeds a threshold, the balancing switch is activated to transfer energy and restore balance, creating a feedback-controlled system that automates the complex switching decisions.
Solution Approach 2:
The balancing switch's on/off state is dynamically adjusted based on real-time voltage conditions. The control system transitions the switching state from off (during normal operation) to on (during voltage imbalance), allowing the circuit topology to change dynamically based on operational needs without requiring complex permanent circuitry.
Data Source
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AI summary
A method for operating a power factor correction (PFC) circuit (110) of an uninterruptible power supply (UPS) apparatus (100) is provided. The PFC circuit (110) includes two T-type converters, and each of the T-type converters includes four switching tubes (Q1-Q4, Q5-Q8). The method includes: converting AC input voltage into a positive bus voltage (V1) across a first capacitor (C1) and a negative bus voltage (V2) across a second capacitor (C2) that is connected in series with the first capacitor (C1) when the UPS apparatus (100) is operated under a normal supply mode; and controlling conduction states of the switching tubes (Q1-Q8) of the T-type converters to balance the positive bus voltage (V1) and the negative bus voltage (V2) when the UPS apparatus (100) is operated under a battery supply mode.