Integrated Transformer Current Sensor Design
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Solution Overview
Problem
Existing current sensors for low-voltage circuits face challenges in accurately measuring current levels, especially at low currents and under overload conditions, while also requiring a compact, cost-effective, and power-independent design.
Innovation Solution
A current sensor arrangement utilizing a transformer with a rectifier circuit and a voltage stabilizing circuit, where a switching component and resistor configuration alternates between energy supply and measurement modes, allowing for current determination without an external power supply and enabling accurate measurement across various current ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate transformer is used for measuring current, then measurement accuracy is improved, but device size and cost increase
Solution Approach 1:
The patent combines the measurement transformer and power supply transformer into a single integrated transformer structure. The primary winding receives the current to be measured, while secondary windings provide both measurement signals and power supply voltage. This merging eliminates the need for separate transformers, reducing device size and cost while maintaining measurement accuracy through dedicated measurement circuits that process the secondary winding outputs.
2Adaptability or versatility
If an internal energy store such as a battery is used for energy supply, then the sensor can operate without external power supply, but the device becomes larger and has limited life and operating temperature range
Solution Approach 1:
The sensor system generates its own power supply voltage by utilizing the current to be measured as input to the transformer. The transformer converts this current into a usable voltage through electromagnetic induction, and the system includes circuitry to regulate and stabilize this self-generated voltage. This self-service approach eliminates batteries and external power supplies, reducing size while providing unlimited operational life and expanded temperature range.
3Adaptability or versatility
If the sensor is designed to measure very low currents (1% of nominal current), then measurement range is improved, but measurement accuracy and reliability deteriorate
Solution Approach 1:
The system employs adjustable transformation ratios in the transformer to adapt to different current measurement ranges. By changing the turns ratio between primary and secondary windings, the system can optimize sensitivity for low current measurements while maintaining accuracy across the full range from 1% to 100% of nominal current. The control unit adjusts measurement parameters and circuit configurations based on the detected current level, ensuring high precision regardless of the measurement range.
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
The solution provides a compact, cost-effective, and accurate current measurement system capable of operating at low currents and under overload conditions, with self-generated power supply, suitable for low-voltage circuits, enabling efficient energy use and communication of current levels.
Implementation Method 1
a conductor of the low-voltage circuit, forming the primary side of a transformer, the secondary side of the transformer being connected to a rectifier circuit
Implementation Method 2
the secondary side of the transformer being connected to a rectifier circuit
Implementation Method 3
the first switching component is switched to be conductive, such that the secondary current of the transformer flows via the first resistor, as a result of which an electrical voltage is dropped across the first resistor
Data Source
AI summary
An arrangement includes a conductor, forming the primary side of a transformer, the secondary side being connected to a rectifier circuit. The rectifier output is connected to a voltage stabilizing circuit for an electronic unit and to a first series circuit formed by a first switching component and a first resistor. In the event of a first voltage value being reached at the first input of the voltage stabilizing circuit, the first switching component is switched to be conductive. The secondary current of the transformer flows via the first resistor to drop an electrical voltage across the first resistor. The electric current of conductor is determinable from the voltage. The use of just one transformer used both for energy generation and for current measurement makes it possible to realize a very compact and small design of a current measuring device having a simple construction.