Voltage Converter Over-Current Isolation for Lower-Cost Protection
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Solution Overview
Problem
Existing voltage converters, particularly totem pole PFC circuits, require high-voltage isolation devices for over-current protection, leading to increased system cost due to the need for high-voltage components.
Innovation Solution
An over-current protection circuit comprising a current sensing circuit, an over-current comparing circuit, an isolation circuit, and a control circuit that generates a low-voltage control signal to turn off switches when an over-current condition is detected, reducing the need for high-voltage components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-voltage isolation devices are used for over-current protection in voltage converters, then over-current protection reliability is improved, but system cost increases
Solution Approach 1:
The patent introduces an isolation circuit as an intermediary component between the high-voltage sensing circuit and the low-voltage control circuit. This isolation circuit enables safe signal transmission across voltage domains without requiring expensive high-voltage isolation devices throughout the entire protection path, thereby maintaining protection reliability while reducing system cost
Solution Approach 2:
The patent changes the voltage level parameter of the protection signal by using an isolation circuit to convert high-voltage sensing signals into low-voltage control signals. This parameter transformation allows the control circuit to operate at lower voltages, eliminating the need for costly high-voltage components while preserving over-current protection functionality
2Reliability
If high-voltage isolation devices are used for over-current protection, then protection effectiveness is improved, but device complexity increases
Solution Approach 1:
The isolation circuit serves as a mediator that simplifies the overall circuit architecture by providing a dedicated interface between high-voltage and low-voltage domains. This centralized isolation approach is less complex than distributing high-voltage isolation capabilities across multiple components throughout the protection circuitry
3Measurement precision
If high-voltage components are used throughout the protection circuit, then over-current detection accuracy is maintained, but manufacturing cost increases
Solution Approach 1:
The patent segments the protection circuit into distinct high-voltage and low-voltage sections. The sensing portion operates at high voltage to maintain detection accuracy, while the control portion operates at low voltage to reduce manufacturing costs. The isolation circuit provides the boundary between these segments, allowing each to be optimized for its specific function
Solution Approach 2:
The patent applies parameter changes by transforming the voltage level of the protection signal from high to low through the isolation circuit. This allows the detection stage to maintain high-voltage accuracy while the control stage benefits from low-voltage cost advantages, achieving both measurement precision and manufacturing economy
Data Source
AI summary
An over-current protection circuit has a current sensing circuit, an over-current comparing circuit, an isolation circuit and a control circuit. The current sensing circuit generates a current sensing signal based on a current flowing through an inductor of a voltage converter. The over-current comparing circuit receives the current sensing signal and generates a first over-current indication signal based on the current sensing signal. The isolation circuit receives the first over-current indication signal and generates a second over-current indication signal based on the first over-current indication signal. The control circuit receives the second over-current indication signal, and generates a control signal to control a switch of the voltage converter. The control circuit turns off the switch when the second over-current indication signal indicates that an over-current condition occurs.