Power Converter Controller Current Limiting Architecture
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing current limiters for power converters often either inhibit operations requiring peak current or increase size and cost by using multiple current sensing elements, and they may not accurately limit average input current without causing delays or offsets.
Innovation Solution
A current limiting architecture that uses a single current sense element to continuously integrate input current through a capacitor, allowing for cycle-to-cycle input current limiting independent of comparator delays or offsets, and includes a controller with a switch, resistors, an amplifier, and a comparator to compare the integrated current to a bias voltage to control the power converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple current sensing elements are used to accurately limit average input current, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple sensing functions into a single current sensing element. The first current sensing element senses both the first current (through the first switch) and the second current (through the second switch), eliminating the need for separate sensing elements for each switch. This merging approach maintains measurement precision while reducing device complexity and cost.
Solution Approach 2:
The single current sensing element performs multiple functions by sensing currents from different phases of the power converter operation. The sensing element is universally used to detect both the first current during the first phase and the second current during the second phase, providing comprehensive current monitoring without requiring dedicated sensing elements for each phase.
2Reliability
If peak current limiting is implemented to protect the power converter, then reliability is improved, but operations requiring peak current are inhibited
Solution Approach 1:
The current limiting mechanism dynamically adapts its behavior based on the operating phase of the power converter. During the first phase, the controller limits the first current based on a first threshold, while during the second phase, it limits the second current based on a second threshold. This dynamic approach allows peak currents necessary for certain operations while providing phase-appropriate protection.
Solution Approach 2:
The patent changes the current limiting parameters according to the operating phase. The first threshold and second threshold are different, allowing the system to permit higher peak currents during phases where they are beneficial while maintaining protection during other phases. This parameter adjustment resolves the contradiction between protection and operational flexibility.
3Measurement precision
If cycle-to-cycle current limiting is implemented independent of comparator delays, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The controller performs preliminary comparison of the sensed current with the threshold before the comparator delay would affect the limiting action. By evaluating whether the first current exceeds the first threshold during the first phase and the second current exceeds the second threshold during the second phase, the controller establishes current limits in advance, achieving accurate cycle-to-cycle current limiting without being affected by comparator delays.
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 effectively limits input current to power converters, preventing excessive current draw while allowing momentary peak currents, reducing size and cost, and improving accuracy by eliminating delays and offsets in current limiting.
Implementation Method 1
A current limiting architecture that uses a single current sense element to continuously integrate input current through a capacitor
Data Source
AI summary
A power supply, comprising a controller comprising a first switch coupled between a first node and a second node, a first resistor coupled between the second node and a third node, a second resistor coupled between the first node and a fourth node, a capacitor coupled between the fourth node and a fifth node, an amplifier coupled at a first input to the fourth node, at a second input to the third node, and at an output to the fifth node, and a comparator coupled at a first input to the fifth node and at a second input to the third node.