Parallel Converter Overcurrent Protection via Resultant Current Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power source apparatuses require multiple current detecting resistors and comparators for each parallel-connected converter, increasing circuit complexity and cost, and struggle to accurately determine which switching element to deactivate during overcurrent conditions when duty ratios exceed 50%.
Innovation Solution
A power source apparatus with a current detector that monitors the resultant current of all converters and a deactivate unit that selectively deactivates active drive signals based on reference values, identifying and prioritizing the switching element with the longest active period for deactivation, thereby reducing the need for individual current detecting resistors and comparators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple current detecting resistors and comparators are used for each parallel-connected converter, then overcurrent detection accuracy is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the current detection function from individual converter-level detection to a system-level detection by placing a single current detecting resistor in the common input line. The comparator then compares this shared current signal against reference values to detect overcurrent conditions across all parallel converters, eliminating the need for multiple separate detection circuits.
Solution Approach 2:
The single current detecting resistor and comparator serve multiple converters simultaneously rather than being dedicated to one converter. This universal detection approach allows the same detection circuitry to monitor and protect all parallel-connected converters, reducing overall system complexity while maintaining detection capability.
2Measurement precision
If multiple current detecting resistors and comparators are used for each parallel-connected converter, then overcurrent detection accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges the current detection function from individual converter-level detection to a system-level detection by placing a single current detecting resistor in the common input line. The comparator then compares this shared current signal against reference values to detect overcurrent conditions across all parallel converters, eliminating the need for multiple separate detection circuits.
Solution Approach 2:
The patent uses a single, simple current detecting resistor and comparator instead of multiple expensive detection circuits. This approach prioritizes cost-effective components that can be easily replaced if needed, rather than investing in redundant expensive detection hardware for each converter.
3Power
If duty ratios exceed 50%, then converter output capability is improved, but accurate determination of which switching element to deactivate becomes difficult
Solution Approach 1:
The patent establishes predetermined reference values that represent safe current thresholds before overcurrent conditions occur. When the detected current exceeds these pre-set reference values, the system automatically deactivates the switching element, eliminating the need for complex real-time calculations to determine which element to deactivate.
Solution Approach 2:
The patent implements a feedback mechanism where the comparator continuously monitors the current through the detecting resistor and compares it against reference values. This closed-loop feedback system automatically provides control signals to deactivate switching elements when thresholds are exceeded, simplifying the control logic despite high duty ratio 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
This solution allows for stable and cost-effective overcurrent protection by identifying and deactivating the appropriate switching element, reducing manufacturing costs and maintaining operational stability even with multiple parallel converters.
Implementation Method 1
When the switching element Q1 is ON, the current Q1i passes in a clockwise direction through a path extending along Vin, L1, Q1, R1, and Vin, to accumulate flux energy in the step-up reactor L1. When the switching element Q1 changes from ON to OFF, the flux energy accumulated in the step-up reactor L1 causes a current passing in a clock wise direction through a path extending along Vin, L1, D1, C1, and Vin, to charge the smoothing capacitor C1.
Implementation Method 2
When the switching element Q2 is ON, the current Q2i passes in a clockwise direction through a path extending along Vin, L2, Q2, R2, and Vin, to accumulate flux energy in the step-up reactor L2. When the switching element Q2 changes from ON to OFF, the flux energy accumulated in the step-up reactor L2 causes a current passing in a clockwise direction through a path extending along Vin, L2, D2, C1, and Vin, to charge the smoothing capacitor C1.
Data Source
AI summary
A power source apparatus includes a first converter having a reactor L1, a switching element Q1, and a rectifier D1; a second converter connected in parallel with the first converter and having a reactor L2, a switching element Q2, and a rectifier D2; a capacitor C1 connected to output ends of the first and second converters; a current detector R1 detecting a resultant current of currents of the first and second converters; a controller 13 driving the switching element Q1 and the switching element Q2; and a selector. In a case where the resultant current indicates a first reference value, if one of first and second drive signals of the controller is active, the active drive signal is deactivated, and if both the first and second drive signals are active, one of the first and second drive signals that is active longer than the other is deactivated.