Inductor Current Estimation in HEV Power Converters
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Solution Overview
Problem
The existing power converter systems in hybrid electric vehicles (HEVs) require current sensors for inductors, which increase cost and size, necessitating a method to determine inductor operating characteristics without them.
Innovation Solution
A system and method to determine inductor current and voltage using a capacitor, duty cycle of a power switch, bus voltage, and inductive coupling sensing, employing open-loop observers and proportional integral control to estimate inductor parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current sensor is used to sense current flow through the inductor, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses voltage measurements across the inductor as an intermediary to indirectly determine inductor current. Instead of directly measuring current with a sensor, the system measures voltage (which is easier and less intrusive) and uses mathematical relationships (v = L di/dt) to calculate the current, thereby avoiding the need for direct current sensors while maintaining measurement capability
Solution Approach 2:
The patent replaces physical current sensors with an electrical/mathematical observation system. By using voltage measurements combined with mathematical models and observers, the system substitutes hardware-based current sensing with a software-based estimation approach, reducing hardware complexity while achieving the same measurement objective
2Reliability
If a current sensor is installed to monitor inductor current, then reliability is improved, but system size and cost increase
Solution Approach 1:
The voltage measurement system serves multiple functions: it directly provides voltage information for control, and simultaneously enables indirect current determination through mathematical relationships. This multi-functional approach eliminates the need for separate current sensors, reducing system size while maintaining reliability through comprehensive state monitoring
Solution Approach 2:
The patent creates a virtual model (observer) that copies the electrical behavior of the inductor circuit. This software-based model replicates the current waveform by processing voltage measurements through mathematical relationships, providing a virtual copy of the current signal without requiring physical current sensing hardware
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 the determination of inductor current without a current sensor, reducing system size and cost while maintaining accurate power conversion in HEVs.
Implementation Method 1
A capacitor may be connected to the storage side of the power converter system
Implementation Method 2
The DC-to-DC power converter in the HEV typically includes an inductor
Data Source
AI summary
A method and system is provided for determining at least one operating characteristic associated with an inductor in a power converter system. The operating characteristic may be current through the inductor. The power converter system may be of the type used in a hybrid electric vehicle (HEV) to convert electric power from a high-voltage traction battery to drive an electric motor and/or a generator in the HEV.