Inverter Torque Restriction for Switching Element Temperature Control
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Solution Overview
Problem
Existing inverter devices for hybrid and electric automobiles face challenges in minimizing torque control to prevent switching element temperature rise, leading to increased weight, volume, and cost, while also compromising handling comfort and control simplicity due to inadequate consideration of ambient temperature in torque restriction methods.
Innovation Solution
An inverter device with a temperature detection section, gate generating section, and torque restriction section that dynamically adjusts torque restriction based on switching element temperature, using a torque restriction mitigation mechanism to minimize unnecessary torque limitations and maintain switching element temperature within safe limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If large heat radiating fins are employed to improve inverter cooling, then cooling performance is improved, but weight and volume are increased
Solution Approach 1:
The patent implements dynamic torque restriction that adapts to real-time temperature conditions. The ECU dynamically adjusts the torque restriction amount based on detected switching element temperature, allowing the system to optimize between cooling performance and power output without requiring oversized passive cooling components.
Solution Approach 2:
The patent changes the operational parameters of the inverter by dynamically adjusting torque restriction amounts based on temperature. Instead of using fixed large heat radiating fins, the system changes the torque parameter in real-time to manage thermal conditions, thereby reducing the need for heavy passive cooling structures.
2Reliability
If torque restriction is applied proportional to maximum ambient temperature, then switching element breakdown is prevented, but handling comfort deteriorates when ambient temperature is low
Solution Approach 1:
The patent implements dynamic torque restriction that adapts to real-time temperature conditions. The ECU dynamically adjusts the torque restriction amount based on detected switching element temperature, allowing the system to optimize between cooling performance and power output without requiring oversized passive cooling components.
Solution Approach 2:
The patent employs a feedback mechanism where the ECU continuously detects switching element temperature and adjusts torque restriction accordingly. This closed-loop control ensures that torque restriction is applied only when necessary (when temperature exceeds thresholds), preventing breakdown while maintaining normal operation and handling comfort under low-temperature conditions.
3Ease of operation
If calibration system or ambient temperature measurement system is introduced to minimize torque control, then torque control is optimized, but device complexity and cost are increased
Solution Approach 1:
The patent employs a feedback mechanism where the ECU continuously detects switching element temperature and adjusts torque restriction accordingly. This closed-loop control ensures that torque restriction is applied only when necessary (when temperature exceeds thresholds), preventing breakdown while maintaining normal operation and handling comfort under low-temperature conditions.
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
The solution minimizes torque restriction, enhances power density, improves handling comfort, and simplifies control by adjusting torque restrictions based on real-time temperature data, preventing switching element breakdown and optimizing performance across varying ambient temperatures.
Implementation Method 1
a temperature detection section arranged in the vicinity of the switching element of aforementioned inverter and that detects the switching element temperature
Implementation Method 2
an inverter that drives and controls an electric motor by converting DC to AC by turning a switching element on and off
Implementation Method 3
the switching elements in the inverter are also raised in temperature due to the effect of steady losses caused by the current flowing in the switching elements themselves, and switching losses due to being turned on and off
Data Source
AI summary
A torque limit section that applies limit to a torque instruction value of an electric motor such that a switching elements temperature is restricted to no more than an element upper limiting temperature includes a torque restriction section that finds a torque restriction value for restricting the torque of the electric motor in accordance with the said switching elements temperature; a torque restriction mitigation section that finds a torque restriction mitigation value for mitigating the torque limit value in accordance with the integrated value of the deviation of the element upper limiting temperature and the switching elements temperature; a first subtractor that finds a torque restriction value by subtracting the torque restriction mitigation value from the torque limit value; and a second subtractor that finds a limited torque instruction value obtained by subtracting the torque limit value from the torque instruction value and outputs this to the gate generating section.