Integrated Axle Drive Rotor Sensor Layout for EMI Robustness
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Solution Overview
Problem
Integrated axle drives for electric vehicles face challenges in maintaining the robustness of rotor position sensors against electromagnetic influences due to varying cable lengths and exposure to external electromagnetic fields.
Innovation Solution
A multi-part rotor position sensor with a sensor target on the rotor and a sensor board on the end shield of the electric machine, connected via a short path through the transmission housing, reducing electromagnetic interference and eliminating the influence of rotor length scaling on sensor placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the rotor position sensor is arranged on the side of the electric machine facing away from the transmission with a long cable to the inverter, then the sensor can be positioned and arranged in a simple manner, but the sensor or signal line is exposed to increased electromagnetic influences
Solution Approach 1:
The patent introduces an intermediary shielding structure (metallic shield or ferrite beads) between the rotor position sensor cable and the electromagnetic sources (inverter and electric machine). This intermediary element intercepts and redirects electromagnetic interference, protecting the sensor signal while allowing the cable to maintain its simple routing path outside the housing.
Solution Approach 2:
The patent utilizes the electromagnetic shielding effect by positioning the cable routing to pass through or near metallic components of the housing or mounting brackets. The previously harmful electromagnetic fields are converted into beneficial shielded zones by the conductive or ferromagnetic materials, turning the cable's external routing from a vulnerability into a protected pathway.
2Adaptability or versatility
If the cable length of the rotor position sensor is increased to reach the inverter, then the sensor can be positioned away from the transmission, but the electromagnetic influences on the sensor or signal line increase
Solution Approach 1:
The patent introduces an intermediary shielding structure (metallic shield or ferrite beads) between the rotor position sensor cable and the electromagnetic sources (inverter and electric machine). This intermediary element intercepts and redirects electromagnetic interference, protecting the sensor signal while allowing the cable to maintain its simple routing path outside the housing.
Solution Approach 2:
The patent applies electromagnetic shielding selectively at critical locations along the cable route, such as near the inverter mounting area or at cable entry points to the housing. This localized shielding approach maintains cable flexibility and routing simplicity while providing targeted protection against electromagnetic influences in the most problematic zones.
3Power
If the rotor length of the electric machine is varied to determine power, then the power of the electric machine can be adjusted, but the cable lengths of the rotor position sensor must be adapted accordingly
Solution Approach 1:
The patent designs the rotor position sensor cable routing and shielding system to be universally applicable across different rotor lengths and power ratings. The shielding structure is integrated into the housing or mounting bracket design, allowing the same basic cable route and protection scheme to be used regardless of the specific electric machine power level, eliminating the need for cable length adaptations.
Solution Approach 2:
The patent combines the cable routing, shielding, and mounting functions into an integrated solution where the cable is mounted along structural components of the housing or bracket assembly. This merging of functions allows the cable system to automatically adapt to different rotor lengths without requiring separate cable length specifications or complex routing modifications for each power level.
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 enhances the accuracy and robustness of the rotor position sensor, reduces electromagnetic interference, and decreases the impact of power changes on sensor positioning, while also reducing cable costs and increasing the longevity of electrical connections.
Implementation Method 1
a sensor board (42) which is arranged, with an air gap to the sensor target, on an end shield (40) of the electric machine
Data Source
AI summary
An integrated axle drive for an at least partially electrically driven motor vehicle, having an electric machine which has a rotor which is mounted so as to be rotatable about a rotor axis, a transmission which is coupled to the electric machine, an inverter which is arranged on the transmission and which is electrically conductively connected to the electric machine, wherein the transmission is arranged between the electric machine and the inverter, a multi-part rotor position sensor, having a sensor target which is arranged and/or formed on the rotor in a rotationally fixed manner and a sensor board which is arranged, with an air gap to the sensor target, on an end shield of the electric machine, wherein the end shield carrying the sensor board is arranged between the transmission and the rotor, and the sensor board is electrically conductively connected to the inverter.