Parallel Thyristor Biasing for Uniform Turn-On Timing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In power systems using parallel thyristors, such as UPSs, there is a lag between the power source providing an input voltage and all thyristors turning on, leading to disturbances and irregularities in power delivery due to differences in threshold voltages and manufacturing variances among thyristors.
Innovation Solution
The implementation of current sources or transformers as biasing elements to generate biasing voltages that ensure simultaneous or near-simultaneous turn-on of thyristors by exceeding their threshold and breakdown voltages, using controllers to manage current pulses and voltages across the thyristors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If thyristors are connected in parallel to increase power capacity, then the power delivery capability is improved, but the turn-on timing uniformity deteriorates due to threshold voltage differences
Solution Approach 1:
The patent applies parameter changes by introducing biasing voltages that dynamically adjust the voltage parameters across each thyristor. The biasing circuitry modifies the threshold voltage condition for turn-on, compensating for manufacturing variations. This allows thyristors with different threshold voltages to turn on simultaneously by changing their operating parameters rather than relying on fixed manufacturing specifications.
Solution Approach 2:
The patent uses biasing elements (resistors, capacitors, or active circuitry) as intermediaries between the power source and the parallel-connected thyristors. These intermediary components generate and distribute biasing voltages that equalize the turn-on conditions across all thyristors, mediating the effect of threshold voltage differences and achieving uniform turn-on timing.
2Adaptability or versatility
If thyristors with different threshold voltages are used in parallel, then the system adaptability is improved, but the power delivery stability deteriorates due to turn-on lag
Solution Approach 1:
The patent implements preliminary action by applying biasing voltages before the thyristors are triggered to turn on. This preliminary biasing equalizes the voltage conditions across all parallel thyristors, ensuring they reach their turn-on threshold simultaneously. The biasing circuitry prepares the thyristors in advance, compensating for threshold voltage differences before the power delivery event occurs.
Solution Approach 2:
The patent employs feedback mechanisms where the biasing circuitry monitors the voltage conditions across parallel thyristors and dynamically adjusts the biasing voltages to maintain equal turn-on timing. This feedback control ensures that even with variations in thyristor characteristics, the system maintains stable and simultaneous turn-on of all parallel devices.
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
This approach ensures that all parallel thyristors turn on simultaneously or nearly simultaneously, reducing power disturbances and irregularities, thereby stabilizing the power delivery to loads.
Implementation Method 1
selectively generate a biasing voltage across the second thyristor to induce a change in a voltage across the second thyristor from a first voltage to a second voltage
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A system for turning on thyristors is presented, the system comprising: an input configured to be coupled to a power source; an output configured to be coupled to a load; a first branch coupled between the input and the output and including a first thyristor having a first threshold voltage; a second branch coupled between the input and the output and coupled in parallel with the first branch, the second branch including a second thyristor having a second threshold voltage higher than the first threshold voltage; and at least one controller configured to control the system to selectively generate a biasing voltage across the second thyristor to induce a change in a voltage across the second thyristor from a first voltage to a second voltage, the first voltage being less than the second threshold voltage and the second voltage being greater than the second threshold voltage.