On-Vehicle Electric Compressor Control Device Thermal Protection
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Solution Overview
Problem
On-vehicle electric compressor control devices are prone to overheating due to high motor currents, especially in high-temperature environments, which can lead to motor shutdown and component damage, and existing rotation speed control methods are insufficient in managing load torque changes.
Innovation Solution
A control device with a temperature acquisition unit, current detector, and motor current controller that sets a threshold current value based on temperature to limit motor current and prevent overheating, including a mechanism to stop the motor when excessive current is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If rotation speed control is performed to manage heat generation, then the control structure is simplified, but the motor current may still become excessively high under high load torque conditions, failing to prevent overheating
Solution Approach 1:
The patent changes the control parameter from rotation speed to motor current. By directly controlling and limiting the motor current based on temperature feedback, the system can effectively manage heat generation even under high load conditions where rotation speed control would be insufficient.
Solution Approach 2:
The patent implements a feedback mechanism where the temperature detector continuously monitors the control device temperature, and this temperature information is fed back to the current limiter to dynamically adjust the motor current threshold, creating a closed-loop control system that adapts to changing thermal conditions.
2Productivity
If the motor current is allowed to increase to meet high load torque demands, then the compressor can maintain operation under heavy loads, but the control device temperature becomes excessively high, risking component damage and shutdown
Solution Approach 1:
The patent introduces dynamic current limiting where the motor current threshold is not fixed but varies dynamically based on the detected temperature. This allows the system to adaptively adjust current limits in real-time, balancing load handling capability with thermal protection.
Solution Approach 2:
The patent implements preventive thermal protection by monitoring temperature and proactively limiting motor current before excessive heat accumulation occurs. The current limiter prevents the motor current from exceeding temperature-appropriate thresholds, cushioning against potential overheating damage before it occurs.
3Ease of operation
If a fixed threshold current value is used for motor current control, then the control implementation is simple, but the control device cannot adapt to temperature variations and may overheat under high-temperature conditions
Solution Approach 1:
The patent transforms the static, fixed threshold current value into a dynamic parameter that automatically adjusts with temperature changes. The threshold current value becomes a function of the detected temperature, enabling the system to adapt to varying thermal conditions without complex manual intervention.
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 and prolonged operation of the electric motor by controlling motor current in accordance with temperature, reducing the risk of component damage and ensuring stable operation across varying load conditions.
Implementation Method 1
a temperature detector that detects a temperature of the control device
Implementation Method 2
a current detector that detects a motor current which is current that flows through the electric motor
Implementation Method 3
When the motor current increases, the amount of heat generated when power loss occurs in the control device for the on-vehicle electric compressor is apt to increase
Data Source
AI summary
A control device for an on-vehicle electric compressor controls and drives an electric motor arranged in the on-vehicle electric compressor. The control device includes a temperature acquisition unit, a current detector, a threshold current value setting unit, and a motor current controller. The temperature acquisition unit acquires a temperature of the control device. The current detector detects a motor current, which is current that flows through the electric motor. The threshold current value setting unit sets a threshold current value in accordance with the temperature of the control device acquired by the temperature acquisition unit. The motor current controller controls the motor current based on a detection result of the current detector so that the motor current becomes less than or equal to the threshold current value.