Filter Circuitry for Electric Machine Feedback Noise Rejection
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Solution Overview
Problem
Noise from switching circuitry in inverters of electric vehicles couples with sensors, causing noise in feedback signals that impact closed-loop operation and electromagnetic compatibility, leading to performance issues and EMC problems.
Innovation Solution
Implementing filter circuitry located close to the electrical machine to remove unwanted noise from feedback signals before they travel through the wiring harness, using common mode chokes and capacitors to isolate and attenuate noise frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If filter circuitry is added to remove noise from feedback signals, then electromagnetic compatibility is improved, but device complexity increases
Solution Approach 1:
The filtering function is segmented from the main inverter circuitry and implemented as separate filter circuitry (common mode chokes and capacitors) positioned close to the electrical machine. This segmentation allows the filtering function to be added without significantly increasing the complexity of the main inverter control system, while still achieving improved electromagnetic compatibility by removing noise from feedback signals at the source.
2Reliability
If filter circuitry is placed close to the electrical machine, then noise filtering effectiveness is improved, but manufacturing complexity increases
Solution Approach 1:
The filter circuitry is positioned close to the electrical machine to perform noise filtering at the earliest possible point in the feedback signal path. By placing the common mode chokes and capacitors near the electrical machine rather than at the inverter control unit, the filtering action occurs preliminary to the noise affecting the feedback signals, maximizing filtering effectiveness while using standard automotive wiring harness integration methods to minimize manufacturing complexity.
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 solution effectively filters noise from feedback signals, improving the performance of the electrical machine and reducing electromagnetic compatibility issues, resulting in more efficient and compact filtering solutions compared to traditional EMC management techniques.
Implementation Method 1
The techniques of this disclosure may include filter circuitry located inside or very close to the electrical machine that filters out the unwanted noise in the feedback signals
Implementation Method 2
using common mode chokes and capacitors to isolate and attenuate noise frequencies
Data Source
AI summary
The disclosure describes techniques to filter unwanted noise from feedback signals of an electrical machine. An electrical machine may receive AC power from an inverter and circuitry in the inverter may cause noise on the AC power signals to the electrical machine. The noise may couple to sensors for the electrical machine and cause noise in the sensor output signals. The sensor output signals may provide feedback for a closed loop control system for the electrical machine and noise may impact the closed loop operation. Also, the noise in the feedback signals may cause electromagnetic compatibility (EMC) issues, either by direct radiated emissions or by coupling to other circuits in the vehicle wiring harness as the feedback signals travel from the electrical machine. The techniques of this disclosure may include filter circuitry located near or inside the electrical machine that filters out the unwanted noise in the feedback signals.