Motor Control Device with Region-Specific Torque Restrictions
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Solution Overview
Problem
Existing motor-control devices fail to adequately protect components prone to overheating, as they do not account for varying operating regions, leading to potential coil and cooling oil overheating issues.
Innovation Solution
A motor-control device with coil and cooling oil temperature detection, implementing region-specific torque restrictions to prevent overheating, prioritizing coil protection at low rotation speeds and cooling oil protection at high rotation speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the motor operates at low rotation speed, then the coil is easily overheated due to insufficient cooling oil diffusion, but if torque restriction is applied to protect the coil, then the motor output is reduced
Solution Approach 1:
The control unit dynamically adjusts the torque restriction amount based on the detected motor rotation speed. At low rotation speeds where coil overheating is more likely, a larger torque restriction is applied. As rotation speed increases and cooling efficiency improves, the torque restriction is reduced, allowing the motor to operate at higher output levels without compromising coil safety.
2Reliability
If the motor operates at high rotation speed, then the cooling oil is sufficiently diffused to prevent coil overheating, but the cooling oil itself tends to overheat due to large heat generation amount
Solution Approach 1:
The control unit dynamically adjusts the torque restriction amount based on the detected motor rotation speed. At high rotation speeds where cooling oil overheating is more likely due to large heat generation, a larger torque restriction is applied to reduce heat input. As rotation speed decreases and heat generation reduces, the torque restriction is reduced, allowing higher motor output while keeping cooling oil temperature within safe limits.
3Reliability
If a single torque restriction threshold is used for all operating regions, then the control logic is simple, but portions susceptible to overheating cannot be properly protected as overheating risks vary by operating region
Solution Approach 1:
The control unit dynamically adjusts the torque restriction amount based on the detected motor rotation speed. At low rotation speeds where coil overheating is more likely, a larger torque restriction is applied. As rotation speed increases and cooling efficiency improves, the torque restriction is reduced, allowing the motor to operate at higher output levels without compromising coil safety.
Solution Approach 2:
The control unit changes the torque restriction parameter according to the motor operation state (rotation speed). By adjusting the restriction amount as a variable parameter rather than using a fixed threshold, the system adapts to different operating conditions where overheating risks vary, providing appropriate protection without requiring complex multi-threshold logic.
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
Effectively prevents overheating of both coils and cooling oil by dynamically adjusting torque restrictions based on operating regions, ensuring reliable protection and extending the lifespan of components.
Implementation Method 1
a motor (16) which is cooled by cooling oil (30) inside a housing (25)
Implementation Method 2
since the cooling oil is scooped up by the rotation of the rotor, the cooling oil does not sufficiently diffuse
Data Source
AI summary
A motor control device includes coil temperature detection means, cooling oil temperature detection means, and a control unit. The control unit implements a coil protection torque restriction and a cooling oil protection torque restriction. The control unit makes it easier for the coil protection torque restriction to be preferentially implemented in a low rotation operating region in which a motor operates at a low rotation speed equal to or lower than a predetermined value, and makes it easier for the cooling oil protection torque restriction to be preferentially implemented in a high rotation operating region in which the motor operates at a higher rotation speed than in the low rotation operating region.