DC-DC Converter Output Current Estimation Using Primary-Side CT Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional low-voltage DC-DC converters in eco-friendly vehicles require redundant current sensors, increasing material costs and suffer from inaccuracies and complexity in estimating output current due to nonlinearity and high computational demands.
Innovation Solution
An apparatus using a CT sensor on the primary side estimates output current through a multi-variable polynomial estimation function, minimizing error rates by curve fitting measured values and optimizing coefficients based on input and output voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Hall sensor current sensor is used to accurately measure output current, then measurement precision is improved, but device complexity and cost increase due to redundant current sensors
Solution Approach 1:
The patent creates a virtual copy of the current sensing function through mathematical modeling. Instead of using a physical Hall sensor on the secondary side, the system creates an equivalent current measurement by transforming primary side measurements (voltage and power) through estimation algorithms, thereby eliminating redundant hardware while maintaining measurement accuracy
Solution Approach 2:
The patent introduces an intermediate mathematical model (estimation function) that mediates between primary side measurements and secondary side current determination. This intermediary approach allows accurate output current estimation without direct physical measurement on the secondary side, reducing sensor requirements
2Device complexity
If conventional estimation methods using CT sensors are used, then device complexity is reduced, but measurement precision deteriorates due to nonlinearity and inaccuracy
Solution Approach 1:
The patent transforms the estimation approach by changing the parameters used in the estimation function. Instead of using simple linear relationships, the system employs a multi-variable polynomial function that incorporates multiple parameters (voltage, power, and their interactions) to accurately capture the nonlinear characteristics of the DC-DC converter, thereby improving estimation precision while maintaining simple sensor configuration
Solution Approach 2:
The patent creates a composite estimation model that combines multiple measurement parameters (input voltage, output voltage, input power) through a polynomial function. This composite approach integrates multiple sources of information to compensate for the limitations of individual measurements, achieving high precision with simple CT sensor configuration
3Measurement precision
If high-order polynomial estimation functions are used, then measurement precision is improved, but device complexity increases due to large memory requirements for storing coefficients
Solution Approach 1:
The patent segments the estimation function into manageable components with fixed coefficients. By dividing the polynomial into specific terms with predetermined coefficients and organizing them in a structured manner, the system reduces the memory burden while maintaining the accuracy benefits of high-order polynomial estimation
Solution Approach 2:
The patent optimizes the parameter representation in the estimation function. By carefully selecting and fixing certain coefficients while allowing others to vary based on operating conditions, the system achieves high estimation precision without requiring excessive memory capacity to store all possible coefficient combinations
4Device complexity
If simple linear estimation is used, then device complexity is reduced, but measurement precision deteriorates due to inability to capture nonlinear characteristics
Solution Approach 1:
The patent transitions from linear to nonlinear parameter relationships by employing a polynomial estimation function. This change in parameter representation allows the system to capture the inherent nonlinear characteristics of the DC-DC converter while maintaining reasonable algorithmic complexity through the use of a structured polynomial model
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
Reduces component count and production costs while achieving accurate output current estimation under varying loads, improving vehicle fuel efficiency and simplifying memory requirements.
Implementation Method 1
a current transformer (CT) sensor 104 connected to the primary side of the low-voltage DC-DC converter 100
Data Source
AI summary
The present disclosure relates to an apparatus for estimating an output current of the secondary side of a low-voltage DC-DC converter using a current transformer (CT) sensor connected to the primary side of the low-voltage DC-DC converter, the low-voltage DC-DC converter including the output current estimating apparatus, and a driving method thereof. The apparatus for estimating an output current of the low-voltage DC-DC converter includes: an input voltage meter for measuring an input voltage of the low-voltage DC-DC converter; a CT voltage meter for measuring a CT voltage correlated with an input current of the low-voltage DC-DC converter; an output voltage meter for measuring an output voltage of the low-voltage DC-DC converter; and an output current estimator that outputs an output current estimate by applying the input voltage, the CT voltage, and the output voltage to an estimation function of a multi-variable polynomial.