Motor Torque Control Using Lubricating Oil Temperature
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Solution Overview
Problem
In vehicle drive systems, the insufficient responsiveness of cooling water temperature sensors leads to inadequate torque limitation when the cooling water temperature rises rapidly, resulting in insufficient motor torque control and potential overheating of motor and inverter elements.
Innovation Solution
A motor control apparatus and method that selectively uses lubricating oil temperature detected by an oil temperature sensor for torque limitation when the elapsed time since the cooling mechanism started is shorter than a predetermined time, and uses refrigerant temperature detected by a refrigerant sensor when the elapsed time exceeds this threshold, allowing for appropriate torque limitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If cooling water temperature sensor is used for torque limitation, then torque control is simplified, but responsiveness is insufficient when cooling water temperature rises rapidly
Solution Approach 1:
The patent introduces lubricating oil temperature as an intermediary parameter to indirectly reflect cooling water temperature changes. When cooling water temperature rises rapidly, the lubricating oil temperature (detected by the oil temperature sensor with faster responsiveness) serves as a substitute indicator to trigger torque limitation, solving the responsiveness problem without adding complex direct measurement systems.
Solution Approach 2:
The system performs preliminary detection of temperature changes using the oil temperature sensor that responds faster to temperature changes. By detecting temperature rise trends in advance through the oil temperature sensor, the system can proactively limit torque before the cooling water temperature reaches critical levels, preventing overheating while maintaining simplified control.
2Speed
If lubricating oil temperature sensor is used for torque limitation, then temperature detection responsiveness is improved, but system complexity increases due to multiple sensors
Solution Approach 1:
The lubricating oil temperature sensor serves multiple functions: it detects both the temperature of the lubricating oil for transmission cooling purposes and simultaneously serves as a surrogate indicator for cooling water temperature to trigger torque limitation. This multi-functionality allows the system to achieve fast temperature detection responsiveness without adding dedicated sensors, thereby avoiding increased system complexity.
Solution Approach 2:
The lubricating oil temperature sensor performs self-service by simultaneously fulfilling its primary function of monitoring transmission cooling and its secondary function of providing early warning for motor cooling status. The sensor leverages its own measurement capability to serve the dual purpose, eliminating the need for additional sensors and keeping the system complexity manageable.
3Measurement precision
If torque limitation is delayed until cooling water temperature is detected, then accurate temperature control is maintained, but motor and inverter elements may overheat during rapid temperature changes
Solution Approach 1:
The system applies preliminary anti-action by using the oil temperature sensor to detect temperature rise trends in advance and triggering torque limitation before the cooling water temperature reaches dangerous levels. This preemptive measure counteracts the potential harm of overheating by acting early, based on the faster-responsive oil temperature detection, rather than waiting for the slower cooling water temperature sensor.
Solution Approach 2:
The system provides beforehand cushioning by establishing a protective mechanism that uses oil temperature detection to anticipate cooling water temperature changes. This creates a buffer that triggers torque limitation in advance, cushioning against the potential damage of overheating that would occur if waiting for the slower cooling water temperature sensor to respond.
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 approach ensures timely and effective torque limitation, protecting the motor and inverter from excessive heat by utilizing the lubricating oil temperature when the cooling water sensor's response is delayed, thereby maintaining system performance and preventing overheating.
Implementation Method 1
a temperature of the cooling water or the lubricating oil detected by a temperature sensor
Implementation Method 2
a temperature of the cooling water or the lubricating oil detected by a temperature sensor
Implementation Method 3
a drive system... in order to prevent the motor temperature and temperature of the inverter element from becoming high
Data Source
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AI summary
A motor control apparatus including a motor 1, a transmission 5 disposed adjacent to the motor 1 or in the vicinity of the motor 1, an oil temperature sensor 5 that detects temperature of lubricating oil of the transmission 5, a cooling mechanism that cools a motor with a refrigerant, a refrigerant sensor that detects temperature of the refrigerant, and a controller that controls torque of the motor 1. Further, the controller selects either the lubricating oil temperature detected by the oil temperature sensor 5 or the refrigerant temperature detected by the refrigerant sensor as detected temperature and applies limitation to torque based on the detected temperature.