Electric Machine Winding Temperature Detection via Phase Line Signal
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Solution Overview
Problem
Existing transmission arrangements in motor vehicles face challenges in accurately and cost-effectively detecting fluid temperature in fluid sums, as traditional temperature sensors are expensive and difficult to verify, and existing methods for determining fluid temperature based on electric motor speed and resistance measurements are limited.
Innovation Solution
A transmission arrangement and method that utilize the temperature-dependent ohmic resistance of windings in an electric machine to detect machine temperature by injecting an excitation signal into a phase line and analyzing the response signal, allowing for the derivation of winding and fluid temperatures, with the option to verify sensor functionality using a comparator and redundant temperature measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is arranged in the fluid sump to detect fluid temperature, then the temperature detection function is achieved, but the cost increases and verification difficulty increases
Solution Approach 1:
The patent creates an electrical copy of the temperature measurement function by using the winding resistance characteristics instead of a physical temperature sensor. The control device measures the electrical resistance of the winding, which correlates with temperature, thereby achieving temperature detection without requiring an additional temperature sensing component in the fluid sump.
Solution Approach 2:
The electric machine's winding itself serves as the temperature sensing element. The winding's inherent electrical resistance property is utilized to detect temperature, eliminating the need for a separate temperature sensor. The machine's own components perform the dual function of electromagnetic operation and temperature indication.
2Measurement precision
If electric motor speed is used to determine fluid temperature based on hydraulic arrangement-specific relationship, then temperature detection is achieved, but measurement accuracy is limited under varying operating conditions
Solution Approach 1:
The patent changes the measurement parameter from mechanical speed (which varies with load and operating conditions) to electrical resistance (which directly correlates with temperature). The control device measures the winding's electrical resistance and uses this parameter to determine temperature, which is less affected by varying mechanical operating conditions and provides more direct temperature information.
3Measurement precision
If resistance measurement is performed with the electric motor running, then temperature detection is achieved, but mechanical influences falsify the response signal
Solution Approach 1:
The patent performs the resistance measurement during a predetermined time period when the electric machine is not energized for providing drive power. This preliminary action ensures that no mechanical rotation or electromagnetic forces are present during measurement, eliminating harmful mechanical influences on the electrical measurement while still allowing temperature detection based on the winding's thermal state from previous operation.
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
Enables simple, cost-effective detection of fluid temperature with reduced mechanical influences and increased reliability, allowing for accurate correlation between winding and fluid temperatures, and verifying sensor performance.
Implementation Method 1
the machine temperature can be detected in a simple manner. According to the invention, the machine temperature is equal to the winding temperature. The detection method according to the invention is based on the fact that the ohmic resistance of the winding is temperature-dependent.
Data Source
Figure 1~1a
Figure 2~3
AI summary
The invention relates to a transmission arrangement (16) for a motor vehicle, comprising a control device (50), a machine power electronics (46), and an electric machine (42) having a plurality of windings (44), which are connected to the machine power electronics (46) via respective phase lines (48). The machine power electronics (46) is connected to the control device (50), wherein the control device (50) has a temperature detection portion (56), which is connected to at least one phase line (48), and which is configured to feed an excitation signal (58) into the phase line (48), and wherein the temperature detection porting (56) is configured to capture a response signal (60) in the phase line (48), and from the response signal (60), to deduce a winding temperature (Tw) of the winding (44) assigned to the phase line (48).