Voltage Sensing Circuit for DC-DC Converters
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Solution Overview
Problem
Conventional DC-DC converters require separate input and output voltage sensing circuits, increasing size and cost, and fail to detect discontinuous mode (DCM) at low loads, preventing application of specific control algorithms.
Innovation Solution
A single voltage sensing circuit using an operational amplifier connected to both terminals of an inductor, with a full-wave rectification bridge, allows simultaneous sensing of input and output voltages and detection of DCM, reducing component count and enabling separate control algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate input and output voltage sensing circuits are disposed at each side of the converter, then voltage sensing accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines the input voltage sensing circuit and output voltage sensing circuit into a single integrated sensing circuit. The operational amplifier is connected to sense both input and output voltages through the inductor, eliminating the need for separate sensing circuits while maintaining sensing accuracy for both voltages.
Solution Approach 2:
The single sensing circuit is designed to perform multiple functions: it senses both input and output voltages of the converter, and detects whether the converter operates in continuous conduction mode (CCM) or discontinuous conduction mode (DCM). This multi-functional approach replaces what would traditionally require separate dedicated circuits.
2Measurement precision
If separate input and output voltage sensing circuits are used, then voltage detection capability is improved, but controller volume increases
Solution Approach 1:
By merging the input and output voltage sensing functions into a single operational amplifier-based circuit, the overall controller volume is reduced. The shared sensing circuit occupies less space than two separate independent sensing circuits would require.
3Device complexity
If conventional sensing circuits are used, then circuit simplicity is maintained, but ability to detect DCM at low load is lost
Solution Approach 1:
The sensing circuit uses feedback through the operational amplifier to monitor the voltage across the inductor. By analyzing the voltage waveform and its characteristics, the circuit can detect when the converter enters DCM operation, even at low load conditions where the detection signal is weak. The operational amplifier amplifies these subtle signals for reliable detection.
Solution Approach 2:
The single sensing circuit is designed to handle both CCM and DCM operation modes, providing reliable detection across the entire operating range including low load conditions where DCM occurs. This universal detection capability is achieved through the operational amplifier's ability to sense and process voltage variations in both modes.
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 the number of components and volume of the controller, enabling accurate sensing of both voltages and detection of DCM, allowing for optimized control strategies, thereby reducing costs and improving operational efficiency.
Implementation Method 1
an operational amplifier connected to both terminals of an inductor so as to detect voltages at both terminals of the inductor of the converter
Implementation Method 2
A full-wave rectification bridge may be interposed between the inductor and the operational amplifier so that two input terminals are connected to the full-wave rectification bridge in the operational amplifier
Data Source
AI summary
A voltage sensing circuit of a converter senses input and output voltages of a converter with only one sensing circuit. The voltage sensing circuit is capable of reducing the number of the components for a controller and the volume thereof to save cost, and detecting whether the discontinuous mode (DCM) is entered or not, thereby to apply a separate control algorithm thereto when the DCM is entered.