Switching Power Converter Controller Direct Current Transformer Sensing
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Solution Overview
Problem
Switching power converters face inefficiencies due to power losses when sensing switch current, particularly when using sense resistors, and there is a need to reduce the cost of external components in power control systems.
Innovation Solution
An integrated circuit controller that directly receives and utilizes the secondary-side current from a current transformer to control power factor correction and regulate link voltage, eliminating the need for external components like filters and reducing power losses by avoiding voltage conversion of the switch current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sense resistor is used to sense switch current, then the current can be sensed, but power losses increase due to the high current across the resistor
Solution Approach 1:
A current transformer is introduced as an intermediary device between the switch and the sensing circuit. The current transformer steps down the high primary current to a lower secondary current that can be safely sensed, thereby reducing power losses while maintaining measurement capability
Solution Approach 2:
The patent replaces the direct resistive sensing method with a magnetic transformation method using a current transformer. This substitution allows current sensing through magnetic coupling rather than direct electrical contact, eliminating the I²R losses associated with sense resistors
2Reliability
If a current transformer with secondary-side filtering components is used, then noise is reduced, but device complexity and component cost increase
Solution Approach 1:
The patent merges the current transformer with the controller into a single integrated circuit package. This consolidation eliminates the need for separate external filtering components and interconnecting traces, reducing overall device complexity while maintaining noise filtering performance through internal integration
Solution Approach 2:
The integrated controller performs multiple functions including current transformation, noise filtering, and control processing within a single device. This multi-functionality eliminates the need for separate dedicated filtering components, reducing the total number of external parts required
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 reduces power losses and lowers component costs by directly sensing and controlling the switch current, enhancing the efficiency and cost-effectiveness of switching power converters.
Implementation Method 1
A primary-side of the current transformer is placed in series with the switch to conduct the switch current. The secondary-side conducts a stepped-down switch current.
Data Source
AI summary
A power control system includes a current transformer to step down a switch current of a switching power converter. In at least one embodiment, the stepped down current is received by a switching power converter controller. Since the current is received by the controller, the current is not converted into a voltage prior to receipt by the controller in order for the controller to monitor an inductor current of the switching power converter. In at least one embodiment, the controller compares the stepped down switch current with a reference current. In at least one embodiment, the controller includes a voltage converter to convert the switch current into a voltage within the controller. The controller compares the voltage representing the switch current with a reference voltage. The controller can use the current or voltage comparisons to control power factor correction and output voltage regulation of a switching power converter.