Curved Motor Phase Terminal for Accurate Current Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing current measurement methods in electric drives with integrated electric machines and converters face challenges such as complex structures, high costs, voltage drops, measurement inaccuracies, and interference from external magnetic fields due to the use of magnetic field sensors without magnetic cores, leading to inefficient and inaccurate control of electric drives.
Innovation Solution
The use of magnetic field sensors without magnetic cores, positioned at a curvature in the phase terminal of the electric machine, to measure phase currents, which focuses the magnetic field and enhances measurement accuracy while reducing system complexity and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If magnetic field sensors without magnetic cores are used for current measurement, then system complexity and weight are reduced, but measurement accuracy deteriorates due to external magnetic field interference
Solution Approach 1:
The patent introduces a magnetic core as an intermediary element between the current conductor and the magnetic field sensor. This magnetic core serves as a mediator that concentrates and guides the magnetic field generated by the current, enabling the sensor to accurately measure the current while filtering out external magnetic field interference. The magnetic core acts as a selective amplifier for the target magnetic field while attenuating other fields.
Solution Approach 2:
The patent changes the physical state and properties of the magnetic field measurement by introducing a magnetic core with specific permeability characteristics. This parameter change allows the system to differentiate between the magnetic field generated by the current to be measured and external magnetic fields, thereby improving measurement accuracy while maintaining the simplified sensor structure.
2Ease of manufacture
If magnetic field sensors without magnetic cores are used, then cost is reduced, but measurement accuracy deteriorates
Solution Approach 1:
The magnetic core serves as a cost-effective intermediary that enables accurate current measurement without requiring complex sensor structures. By using a relatively simple magnetic core component rather than complex sensor designs, the patent achieves measurement accuracy while keeping manufacturing costs low.
3Measurement precision
If sensors are connected to current lines for measurement, then measurement accuracy is improved, but voltage drops and losses increase
Solution Approach 1:
The patent replaces the electrical connection method (shunt resistors or current transformers requiring electrical contact) with a magnetic field-based measurement approach. This substitution eliminates the need for direct electrical connections between the sensor and current line, thereby avoiding voltage drops and energy losses while still achieving accurate current measurement through magnetic field detection.
4Measurement precision
If magnetic cores are used to enclose conductors for accurate measurement, then measurement accuracy is improved, but space requirement and weight increase
Solution Approach 1:
Instead of using large magnetic cores that completely enclose the conductor, the patent applies magnetic core material locally at specific positions where the magnetic field concentration is most effective. This localized approach maintains measurement accuracy while significantly reducing the overall volume and weight of the magnetic core structure.
Solution Approach 2:
The patent employs curved or annular magnetic core structures that follow the geometry of the current conductor, rather than rigid rectangular enclosures. This curved design allows for more compact integration and reduces the space requirement while maintaining effective magnetic field concentration for accurate measurement.
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
This approach improves measurement accuracy and efficiency by amplifying the magnetic field at the sensor, reduces interference, and minimizes the impact of vibrations, resulting in a more robust and cost-effective electric drive system.
Implementation Method 1
a measurement principle of magnetic field measurement is used in that a magnetic field sensor without a magnetic core is arranged at a curvature in the phase terminal
Implementation Method 2
which focuses the magnetic field and enhances measurement accuracy
Data Source
AI summary
An electric drive may include an electric motor phase terminal for phase current measurement. The electric drive may include an inverter, an electric machine having a plurality of phase current branches, the electric machine and the inverter being arranged together in a housing, and the one magnetic field sensor without a magnetic core for measuring a current of at least one of said plurality of phase current branches. At least one phase current branch of the plurality of phase current branches may include a slot bar which is arranged at least partially in a slot of the electric machine and which forms a phase terminal outside the slot, and the phase terminal may have a curvature in the region of which the at least one magnetic field sensor without a magnetic core is arranged.