Self-Powered Rotor Sensing Using Stray-Field Induction
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Solution Overview
Problem
Existing electric machines face challenges in supplying sensors associated with the rotor with sufficient electrical energy, leading to limited continuous power due to unknown rotor temperatures and the need for safety margins, which can result in suboptimal operation and overheating risks.
Innovation Solution
A rotor design for electric machines that includes a sensor element and a signal processing unit connected to an induction coil, which generates electrical energy from the fundamental wave field of the magnetic stray field, allowing for wireless energy transmission and reducing the need for external power sources like batteries, enabling precise temperature measurement and improved operational efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors are installed on the rotor to monitor temperature and condition variables, then measurement precision is improved, but device complexity increases due to the need for power supply systems
Solution Approach 1:
The rotor system generates its own electrical energy through the induction coil interacting with the magnetic stray field during normal operation. This self-powered approach eliminates the need for external power supply systems like batteries or collection rings, thereby reducing device complexity while maintaining the capability to power temperature sensors and signal processing units on the rotating rotor
Solution Approach 2:
The induction coil acts as an intermediary that converts the previously wasted magnetic stray field into useful electrical energy. By tuning the induction coil to the modulation frequency of the fundamental wave field, it harvests energy from the magnetic field that already exists during motor operation, providing power to sensors without adding complex power transmission infrastructure
2Reliability
If safety margins are applied to maximum rotor temperature, then reliability is improved, but productivity decreases due to limited continuous power
Solution Approach 1:
Temperature sensors on the rotor continuously monitor the actual rotor temperature and feed this information to the control device. The control device uses this real-time feedback to dynamically adjust the maximum permissible power, allowing operation at or near the actual temperature limits rather than conservative estimates, thereby eliminating unnecessary safety margins and maximizing continuous power output
Solution Approach 2:
The system performs periodic temperature measurements and evaluations during operation, allowing the control device to continuously optimize the power output based on actual thermal conditions. This periodic monitoring enables the system to operate at maximum permissible power levels while maintaining reliability through real-time temperature awareness
3Ease of operation
If collection rings or batteries are used to power rotor sensors, then ease of operation is improved, but device complexity increases and installation becomes more difficult
Solution Approach 1:
The rotor system generates its own electrical energy through the induction coil interacting with the magnetic stray field during normal operation. This self-powered approach eliminates the need for external power supply systems like batteries or collection rings, thereby reducing device complexity while maintaining the capability to power temperature sensors and signal processing units on the rotating rotor
Solution Approach 2:
The invention extracts useful electrical energy from the previously underutilized magnetic stray field that exists during motor operation. By placing the induction coil on the rotor and tuning it to the modulation frequency, the system harvests energy directly from the operating magnetic field, eliminating the need for separate power transmission infrastructure and simplifying the overall system
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 allows for efficient energy supply to sensors and signal processing units, reducing the risk of overheating and enabling optimal operation of electric machines by accurately monitoring rotor conditions, such as temperature, without the need for complex power supply systems or speed-dependent energy generation.
Implementation Method 1
The induction coil is tuned to a modulation of a fundamental wave field of a magnetic front stray field formed during the operation of the electric machine with pulsed voltage, with the induction coil being configured for generating electrical energy from the fundamental wave field
Data Source
AI summary
A rotor (1) for an electric machine (2) operated with a pulsed voltage, the rotor (1) having at least one sensor element (3) for detecting at least one condition variable of the rotor (1), and a signal processing unit (4) connected to the at least one sensor element (3), the signal processing unit (4) generating measured data based on the at least one condition variable of the rotor (1) and transmitting the measured data to a control device (5). The rotor (1) further having at least one induction coil (7) at least indirectly supported on an end face of the rotor (1), the at least one induction coil (7) being tuned to a modulation of a fundamental wave field of a magnetic front stray field (12) formed during operation of the electric machine (2) with pulsed voltage to generate electrical energy from the fundamental wave field.