Converter Current Detection Using Single-Sensor Copying

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Solution Overview

Problem

Existing converters used in pulse-width modulated systems face challenges in accurately determining the current space vector, particularly due to current ripples and the need for expensive potential-separating current sensors, which are not effective at all angles and switching states.

Innovation Solution

A converter design with signal electronics and power output stages in three half-bridges, using devices for current sampling in the upper or lower branches, allowing adjustable amplification and adaptable resolution, enabling precise current detection without angular distortion or offset, and allowing the same control electronics to be used across different power switches.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If potential-separating current sensors are used in the output branches, then current detection is possible, but the cost increases significantly

Engineering Contradiction:

Improvecurrent detection capabilityVSAvoidcost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent uses a single current sensor to detect current in one branch, then mathematically calculates (copies) the current information for other branches based on circuit relationships and switching states, avoiding the need for multiple expensive potential-separating sensors

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent introduces an intermediate calculation process that uses the detected current value combined with switching state information to derive current space vector components, serving as a mediator between single-point detection and complete current measurement

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If current sensors are placed in output branches, then continuous current signals are obtained, but expensive potential-separating devices are required

Engineering Contradiction:

Improvecontinuous current signalVSAvoidcost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent generates continuous current signals by mathematically reconstructing current information from single-point measurements combined with switching state data, copying the continuous signal characteristic without requiring continuous physical sensing in all branches

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent replaces physical continuous sensing in multiple branches with a combination of single-point physical measurement and computational processing, substituting mechanical/electrical sensing complexity with algorithmic processing

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If shunt resistors are used in all lower branches, then all three current measuring values are detected, but the current space vector cannot be determined in shaded regions

Engineering Contradiction:

Improvecurrent measuring valuesVSAvoidcurrent space vector determination

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent dynamically selects which current measurement and switching state combination to use based on the current operating region, adapting the measurement strategy to ensure reliable current space vector determination across all operating conditions including previously problematic shaded regions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the interpretation parameters of the measured current value based on switching states, using the same physical measurement but different calculation approaches depending on the operational context to maintain accuracy across all regions

Inventive Principle:

Principle #35Parameter changes

4Measurement precision

If zero vector is applied for current measurement, then current measuring signal is obtained, but measurement is not available in shaded regions where zero vector is not used

Engineering Contradiction:

Improvecurrent measuring signalVSAvoidmeasurement availability

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent creates a universal current measurement approach that works across all switching states and operating regions by combining single-branch measurement with switching state information, making the measurement system versatile rather than limited to specific zero-vector regions

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent uses switching state information as an intermediary that bridges the gap between limited physical measurement and complete current space vector determination, enabling measurement availability across all regions without requiring physical sensors in all branches

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11245340B2Circuit board, method for determining a current space vector, converter, circuit board and series of converters

Publication Date: 2022.02.08 SEW EURODRIVE GMBH & CO KG

AI summary

In circuit board for a converter, including control electronics, the circuit board includes a device for current detection, the device respectively having at least two measuring amplifier circuits, only the output of one of the measuring amplifier circuits being supplied as the detected current value to the control electronics of the converter.