GaN Bridgeless PFC Current Sensing via Return Path Resistor
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Solution Overview
Problem
Current power factor correction (PFC) circuits in switching mode power supplies face inefficiencies due to diode conduction losses and challenges in accurate current sensing, particularly in bridgeless PFC circuits, which affect power efficiency and increase costs and size.
Innovation Solution
The use of Gallium Nitride (GaN) field-effect transistors and a sense resistor on the return path to measure total inductor current, eliminating the need for hall-effect sensors and current transformers, thereby improving power efficiency and reducing costs and size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional current sensing methods (hall-effect sensors, current transformers) are used in bridgeless PFC circuits, then current measurement can be achieved, but device complexity, cost, and size increase
Solution Approach 1:
The patent extracts the current sensing function from external complex components (hall-effect sensors, current transformers) and implements it using a simple sense resistor integrated into the return path of the bridgeless PFC circuit. This eliminates the need for separate current sensing components while maintaining measurement capability.
Solution Approach 2:
The sense resistor serves multiple functions: it provides current sensing for the controller, enables power factor correction control, and is integrated into the existing return path without requiring separate dedicated sensing circuitry. This multi-functionality reduces overall device complexity.
2Reliability
If diode conduction losses are present in PFC circuits, then circuit operation is maintained, but power efficiency decreases
Solution Approach 1:
The patent changes the electrical parameters by using GaN transistors with significantly lower on-resistance compared to traditional silicon MOSFETs. This parameter change reduces the voltage drop across the switching device during conduction, thereby reducing power losses while maintaining reliable circuit operation.
3Loss of energy
If GaN transistors are used with sense resistor on return path, then power efficiency and measurement accuracy improve, but manufacturing complexity increases
Solution Approach 1:
The patent merges the sense resistor directly into the return path circuitry of the bridgeless PFC circuit, combining the current sensing function with the existing power circuit. This integration approach simplifies manufacturing by reducing the number of discrete components and interconnections required, despite using advanced GaN technology.
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 enhances power factor correction by accurately measuring return current, reducing switching losses, and improving power loop efficiency, leading to higher power factor and reduced overall size and cost of PFC circuits.
Implementation Method 1
a sense resistor on the return path to measure total inductor current
Implementation Method 2
The use of Gallium Nitride (GaN) field-effect transistors and a sense resistor on the return path to measure total inductor current, eliminating the need for hall-effect sensors and current transformers, thereby improving power efficiency
Data Source
AI summary
Current sensing apparatus in power factor correction circuits and related methods are disclosed. An example power factor correction circuit includes a first Gallium Nitride (GaN) transistor having a first current terminal and a second current terminal, a second GaN transistor having a third current terminal and a fourth current terminal, a first diode having a first anode, a second diode having a second anode, the second anode coupled to the first anode, and a resistor having a first terminal and a second terminal, the first terminal coupled to the second current terminal and the fourth current terminal, the second terminal coupled to the first anode and the second anode.