Observer-Based Current Sensor for Bi-Directional DC to DC Converter

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Solution Overview

Problem

Existing DC to DC power conversion systems, such as Dual Active Bridges, require expensive hardware current sensors to maintain high power quality, which occupy significant space on printed wiring boards and lack efficient load disturbance rejection.

Innovation Solution

A bi-directional DC to DC converter with an observer-based estimated current sensor module that simulates a physical current sensor, allowing for accurate estimation of inner current states and feedforward of average DC link current to eliminate delays and track load disturbances, thereby replacing the need for physical current sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If physical current sensors are used to maintain high power quality and enable load disturbance rejection, then measurement precision and reliability are improved, but device complexity and cost increase significantly

Engineering Contradiction:

Improvecurrent measurement precisionVSAvoidsensor circuit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent creates a virtual copy of the current sensor functionality through software-based current observers that estimate current states using mathematical models and available measurements, eliminating the need for physical current sensors while maintaining measurement precision

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent replaces the physical hardware current sensing system with a computational/software-based current estimation system, substituting mechanical/electrical sensing components with algorithmic processing of voltage and current relationships

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If physical current sensors and supporting circuits are installed, then current measurement capability is improved, but area occupied on printed wiring board assembly increases

Engineering Contradiction:

Improvecurrent sensing capabilityVSAvoidPWBA area

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent eliminates physical current sensors by implementing virtual current observers in software, removing the need for sensor components and their supporting circuits on the printed wiring board, thereby freeing up significant board area

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent extracts the current sensing function from physical hardware components and relocates it to a software-based estimation algorithm, removing the sensor and its supporting circuitry from the hardware design

Inventive Principle:

Principle #2Taking out (Extraction)

3Device complexity

If conventional control without feedforward is used, then device complexity is reduced, but load disturbance rejection capability deteriorates

Engineering Contradiction:

Improvecontrol system complexityVSAvoidload disturbance rejection

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent implements feedforward control that anticipates load disturbances by using the average DC link current as a predictive input, allowing the system to proactively compensate for disturbances before they affect output voltage quality

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent combines feedback control with feedforward action, where the current observer continuously monitors and estimates current states while the feedforward path uses average DC link current to preemptively counteract load disturbances

Inventive Principle:

Principle #23Feedback

4Measurement precision

If physical current sensors are used, then current measurement accuracy is improved, but cost increases due to expensive sensor hardware

Engineering Contradiction:

Improvecurrent measurement accuracyVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive physical current sensors with inexpensive software-based current observers that run on the controller, maintaining measurement accuracy while eliminating costly hardware components

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent uses computationally inexpensive algorithms implemented in software rather than expensive physical sensors, reducing the cost of the measurement system while achieving the same functional objective

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentEP3499701B1Bi-directional DC to DC signal conversion using observer based estimated current sensor

Publication Date: 2021.01.27 HAMILTON SUNDSTRAND CORP

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AI summary

In accordance with at least one aspect of this disclosure, a bi-directional DC to DC converter includes a DC to DC conversion circuit (101), and a controller (105) operatively connected to the conversion circuit to control a current output of the conversion circuit, wherein the controller includes an observer based estimated current sensor module (109) which is configured to simulate a physical current sensor and to input an estimated output current feedback inner state signal ^ėo into a voltage output command feedback loop of the controller. The current sensor module can include an estimated sensor feedback loop.