Power Bypass Apparatus Current Sharing Control
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Solution Overview
Problem
Existing power bypass systems in UPSs face failures due to thermal runaway, reduced efficiency, and control failures in large-power UPSs, primarily because of the negative temperature coefficient characteristics of thyristors and the increased power consumption and cost associated with large-value inductors used to mitigate these issues.
Innovation Solution
A power bypass apparatus with a current-sharing function that includes at least two bypass switch assemblies and a control unit, where each assembly has a controllable switch, a cooling unit, and a temperature detection unit. The control unit adjusts the switch's turned-on duration and cooling capacity to ensure equal current flow through both switches, preventing thermal runaway and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large-value inductor is connected in series to the TRIAC to prevent thermal runaway, then the reliability of the power bypass function is improved, but the power consumption increases and the circuit cost and size increase
Solution Approach 1:
The patent extracts the current-sharing function from the inductor and transfers it to the control unit. The control unit detects current values through current sensors and adjusts the trigger angles of multiple TRIACs independently, eliminating the need for large-value series inductors while maintaining reliable current sharing and reducing power consumption.
Solution Approach 2:
The patent implements a feedback control mechanism where the control unit continuously detects the current values flowing through each TRIAC via current sensors, compares them with reference values, and dynamically adjusts the trigger angles to maintain balanced current distribution. This active feedback control replaces the passive inductor-based current sharing, improving reliability without increasing power consumption.
2Reliability
If a large-value inductor is connected in series to the TRIAC to prevent thermal runaway, then the reliability of the power bypass function is improved, but the circuit cost and circuit size increase
Solution Approach 1:
The patent removes the large-value inductor from the circuit and extracts its current-sharing function into the control unit. The control unit uses current sensors to detect current values and adjusts trigger angles electronically, significantly reducing circuit size and component count while maintaining reliable current sharing.
Solution Approach 2:
The patent replaces the passive mechanical inductor-based current sharing with an active electronic control system. The control unit uses electronic sensors and signal processing to achieve current balancing, substituting bulky passive components with compact electronic circuitry, thereby reducing circuit size and complexity.
3Ease of operation
If the NTC characteristic of the TRIAC is exploited for current sharing, then the ease of operation is improved, but the system becomes unstable due to thermal runaway
Solution Approach 1:
The patent applies preliminary anti-action by having the control unit proactively detect current imbalances and adjust trigger angles before thermal runaway can occur. The system continuously monitors current values and makes preemptive adjustments to maintain stability, counteracting the inherent NTC instability rather than exploiting it.
Solution Approach 2:
The patent implements feedback control where the control unit detects current values through current sensors and adjusts the trigger angles of TRIACs based on detected imbalances. This closed-loop feedback stabilizes the system by continuously correcting deviations from desired current distribution, preventing thermal runaway while maintaining ease of operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively prevents power bypass failures, increases overall efficiency, and enables successful current-sharing operations in large-power UPSs by controlling the switch duration and cooling capacity to manage temperature and current flow.
Implementation Method 1
The controllable switch is disposed on a heat dissipation unit. The cooling unit is correspondingly disposed to the heat dissipation unit, and the cooling unit cools the controllable switch according to a cooling capacity of the cooling unit.
Implementation Method 2
The controllable switch is disposed on a heat dissipation unit... the cooling unit cools the controllable switch according to a cooling capacity of the cooling unit
Implementation Method 3
The temperature detection unit is correspondingly disposed to the heat dissipation unit, and the temperature detection unit detects a temperature value of the controllable switch and produces a temperature detection signal having information of the temperature value.
Implementation Method 4
Each of the bypass switch assemblies includes a controllable switch... controls a switch turned-on duration of at least one of the controllable switches... so that current values flowing through the controllable switches are identical
Data Source
AI summary
A power bypass apparatus with a current-sharing function includes at least two bypass switch assemblies and a control unit. Each bypass switch assembly includes a controllable switch, a cooling unit, and a temperature detection unit. Each the temperature detection unit, correspondingly disposed to a heat-dissipating unit, detects a temperature value of the controllable switch to produce a temperature detection signal. The control unit receives the temperature detection signals and outputs at least two switch control signals to control at least one of the controllable switches or outputs at least two cooling unit control signals to control at least one of the cooling units, thus making currents flowing through the controllable switches identical. Accordingly, it is to increase overall efficiency of a power system and implement current-sharing function of the power system providing high power.