Electric Compressor Temperature Estimation for Overheat Protection
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Solution Overview
Problem
Existing air conditioning apparatuses for vehicles struggle to effectively estimate motor coil temperature and discharge temperature of electric compressors, especially in abnormal high-temperature environments, leading to inadequate overheating protection without additional temperature detection means.
Innovation Solution
An air conditioning apparatus with an inverter-integrated electric compressor that includes a temperature detection unit for the semiconductor switching device, allowing the control unit to estimate discharge temperature and motor coil temperature based on detected temperature, rotational speed, and motive force, eliminating the need for additional temperature sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are installed to directly detect discharge temperature and motor coil temperature, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses an intermediary estimation approach where the control unit calculates discharge temperature and motor coil temperature based on readily available parameters (discharge pressure, rotational speed, input current) rather than direct sensor measurement. This intermediary calculation method avoids the need for additional temperature sensors while providing sufficient temperature information for control purposes.
Solution Approach 2:
The patent replaces the physical temperature sensor system with a computational estimation system. Instead of using mechanical/physical sensors to directly measure temperature, the system uses mathematical calculations based on other measurable parameters (pressure, speed, current) to estimate temperature, thereby eliminating the need for additional sensing hardware.
2Reliability
If temperature sensors are installed to detect discharge temperature and motor coil temperature, then reliability of overheating protection is improved, but manufacturing cost increases
Solution Approach 1:
The control unit acts as an intermediary that computes temperature values from other measurable parameters. This approach maintains reliable overheating protection by accurately estimating temperatures through calculation rather than requiring expensive additional temperature sensors, thereby reducing manufacturing costs while preserving safety functionality.
Solution Approach 2:
The patent creates a computational model that copies the temperature information needed for protection without physically measuring temperature. By using discharge pressure, rotational speed, and input current as proxies, the system replicates the temperature data functionally, achieving reliable protection at lower cost.
3Device complexity
If estimation methods using discharge pressure, rotational speed, and input current are used, then device complexity is reduced, but measurement precision deteriorates in abnormal high-temperature environments
Solution Approach 1:
The control unit continuously monitors discharge pressure, rotational speed, and input current, and uses this feedback to dynamically estimate temperature. This feedback mechanism allows the system to adapt to changing operating conditions and maintain reasonable estimation accuracy even in abnormal environments, while keeping the configuration simple.
Solution Approach 2:
The patent changes the parameters used for temperature estimation by incorporating multiple variables (discharge pressure, rotational speed, input current) rather than relying on a single parameter. This multi-parameter approach improves estimation accuracy in abnormal conditions while maintaining configuration simplicity through computational methods.
4Measurement precision
If additional temperature detection means are added to improve temperature detection accuracy in abnormal conditions, then measurement precision is improved, but volume of the apparatus increases
Solution Approach 1:
The control unit serves as an intermediary that computes temperature information from existing sensor data (pressure, speed, current) without requiring additional temperature sensors. This approach maintains accurate temperature detection capability while avoiding the volume increase that would result from installing additional detection hardware.
Solution Approach 2:
The control unit performs multiple functions: it controls compressor operation, monitors system parameters, and estimates temperature. By making the control unit multi-functional, the patent eliminates the need for separate temperature detection hardware, thereby maintaining detection accuracy without increasing apparatus volume.
Data Source
AI summary
Provided is an air conditioning apparatus that is capable of suppressing increases in volume and cost of the apparatus and performing more suitable overheating protection. An electric compressor is an inverter-integrated electric compressor (10) integrally including a compressor (5), an electric motor (6) that drives the compressor (5), and an inverter (7) including a temperature sensor (11) that detects the temperature in the vicinity of a semiconductor switching device, wherein a controller (3) estimates a discharge temperature of the compressor (5) on the basis of a correlation of respective pressure loading characteristics for the detected temperature of the inverter (7), for the rotational speed of the compressor (5), and for the motive force of the compressor (5) in a refrigerating cycle (2).