Auxiliary Winding Current Sensor for High-Accuracy Over-Current Measurement
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Solution Overview
Problem
Solid state power controllers (SSPCs) require high accuracy current sensors with a wide measuring range to detect over-currents up to 2000 amps, but existing solutions like resistive shunts suffer from high power losses and Hall effect sensors need larger sizes to maintain accuracy, which is undesirable for size and weight reduction.
Innovation Solution
A current sensor system using a primary conductor and an auxiliary conductor with partial flux cancellation, where the auxiliary conductor provides an auxiliary current opposite to the primary current, allowing the sensor to accurately measure both steady-state and over-currents using a smaller size, preventing magnetic core saturation and reducing output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Hall effect sensors are used to accurately sense high over-currents, then measurement precision is improved, but the size and weight of the sensor increases
Solution Approach 1:
The current sensing function is divided into two segments: a primary conductor for carrying the main current and an auxiliary conductor for providing flux cancellation. This segmentation allows the magnetic core to handle high currents without saturation while keeping the sensor size compact.
Solution Approach 2:
The auxiliary conductor provides preliminary anti-action by generating a magnetic flux that opposes and cancels part of the flux from the primary conductor. This prevents magnetic core saturation before it occurs, enabling accurate measurement of high currents without increasing sensor size.
2Measurement precision
If Hall effect sensors are used to accurately sense high over-currents, then measurement precision is improved, but the device complexity increases
Solution Approach 1:
The auxiliary conductor is merged with the magnetic core structure, forming an integrated assembly. The auxiliary winding is wrapped around the magnetic core, combining the flux cancellation function with the core structure itself, thereby reducing overall device complexity.
Solution Approach 2:
The magnetic core serves multiple functions: it concentrates the magnetic field for the Hall effect sensor and simultaneously provides a path for the auxiliary flux cancellation. This multi-functionality reduces the need for separate components, simplifying the overall device structure.
3Measurement precision
If resistive shunts are used for current sensing, then measurement precision is improved, but power losses increase
Solution Approach 1:
The resistive shunt measurement method is replaced with a magnetic field-based Hall effect sensor system. This substitution eliminates the need for high-power resistive elements, dramatically reducing power losses while maintaining measurement accuracy through magnetic flux sensing and cancellation.
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 accurate sensing of primary currents up to 1000% of steady-state values with a smaller sensor size, reducing power losses and weight while maintaining measurement accuracy.
Implementation Method 1
an auxiliary conductor with partial flux cancellation, where the auxiliary conductor provides an auxiliary current opposite to the primary current
Implementation Method 2
Hall effect sensors are non-contact sensors that sense current based upon a magnetic field created by current flowing in a conductor
Data Source
AI summary
A power controller controls power to a load and includes a primary current sensor, a controller and a current source. The primary current sensor includes a primary conductor and an auxiliary conductor. The primary conductor carries a primary current to the load and the auxiliary conductor carries an auxiliary current in the opposite direction of the primary current to provide partial flux cancellation. The primary current sensor provides an output voltage based upon a magnetic field generated by the primary current and auxiliary current. The controller determines the primary current based upon the output voltage and the auxiliary current. The current source provides the auxiliary current. The controller controls the current source to provide the auxiliary current to the auxiliary conductor if the primary current is greater than a threshold value.