Power FET Current Sensing for Parallel Switch Loss Control
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Solution Overview
Problem
There is a need in the art to provide approaches for monitoring current flows in electronic power converters, particularly for determining the number of parallel-connected electronic switches to be closed in order to optimize power loss reduction and control.
Innovation Solution
A sensor system comprising a power FET with a sense resistance and a regulator circuit that monitors the current flowing through the power FET, using a scaled version of the power FET and an operational amplifier to regulate the current through the sense resistance, allowing for the measurement of both instantaneous and average current values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If multiple electronic switches are connected in parallel to reduce power losses, then power loss reduction is improved, but device complexity increases
Solution Approach 1:
The patent divides a single electronic switch into multiple parallel-connected electronic switches (e.g., multiple FETs). Each switch can be independently controlled, allowing the system to segment the total current load across multiple devices. This segmentation reduces power losses by optimizing the on-resistance characteristics while maintaining manageable complexity through modular architecture.
Solution Approach 2:
The control circuit dynamically adjusts the number of parallel-connected electronic switches based on operating conditions such as load current. During high-current periods, more switches are activated to reduce resistive losses; during low-current periods, fewer switches are active to minimize switching losses and complexity. This dynamic adaptation resolves the contradiction by making the system complexity variable rather than fixed.
2Loss of energy
If current monitoring is implemented to optimize switch control, then power loss reduction is improved, but device complexity increases
Solution Approach 1:
The patent incorporates current monitoring circuits that provide feedback to the control logic, enabling it to adjust the number of active parallel switches based on actual load conditions. The feedback mechanism tracks parameters such as output current and duty cycle, allowing the control circuit to optimize the switching configuration in real-time. This feedback-driven approach reduces power losses by ensuring the system operates with the optimal number of switches active for each operating condition.
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
Enables effective monitoring and control of current flows, optimizing the number of electronic switches to be closed, thereby reducing power losses and improving the efficiency of the electronic power converter.
Implementation Method 1
regulate a first current flowing through the sense resistance, such that the voltage drop at the sense resistance corresponds to the voltage drop between the first and second terminal of the power FET
Data Source
AI summary
A sensor circuit for a power FET monitors current flowing through the FET and includes a regulator circuit regulating a first current flowing through a sense resistance, so voltage drop at the sense resistance corresponds to voltage drop between terminals of the FET. A measurement circuit provides a second current corresponding (or being proportional) to the first current. A first switch selectively applies the second current to a resistor based on a first control signal, and a low pass filter generates a low-pass filtered signal by filtering voltage at the resistor. A voltage follower generates a replica of the low-pass filtered signal, and a second switch selectively applies the replica to the resistor. When the FET is closed, a control circuit closes the first switch and opens the second electronic switch. When the FET is opened, the control circuit opens the first electronic switch and closes the second electronic switch.