Inverter Control Unit Sensor Failure Handling
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Solution Overview
Problem
Existing control systems for electrically driven vehicles, such as hybrid and electric vehicles, fail to protect switching devices in inverters from overheating when the coolant temperature sensor fails, leading to potential damage and disruption of vehicle travel.
Innovation Solution
A control device and method that includes switching device temperature sensors and a coolant temperature sensor failure detection system, which allows the vehicle to continue driving by using the switching device temperature sensor readings to simulate coolant temperature data when the coolant temperature sensor fails, and adjusts motor output torque to prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the coolant temperature sensor fails, then the actual coolant temperature becomes unknown, but the switching devices may overheat and break
Solution Approach 1:
The patent creates a virtual copy of the coolant temperature sensor by using the generator inverter's switching device temperature sensor to simulate coolant temperature detection. When the actual coolant temperature sensor fails, the control unit replaces the missing coolant temperature data with the switching device temperature data from the generator inverter, allowing the motor inverter's torque command to be adjusted based on this virtual temperature reading to prevent overheating.
2Reliability
If the motor drive is stopped immediately when coolant temperature sensor failure is detected, then switching devices are protected, but the vehicle becomes unable to travel
Solution Approach 1:
The patent introduces an intermediary solution by using the generator inverter's temperature sensor as a mediator to provide temperature information for controlling the motor inverter. This intermediary approach allows the motor drive to continue operating without immediate shutdown while still providing sufficient temperature-based protection through the borrowed temperature data from the generator side.
3Productivity
If torque command is adjusted based on normal coolant temperature assumption, then motor output is maintained, but switching devices may break when cooling system is abnormal
Solution Approach 1:
The patent implements a feedback mechanism where the control unit continuously monitors the virtual coolant temperature (derived from generator inverter's switching device temperature) and adjusts the motor inverter's torque command accordingly. When the virtual temperature indicates high temperature conditions, the torque command is automatically reduced to prevent switching device overheating, creating a closed-loop protection system that responds to temperature conditions in real-time.
Data Source
AI summary
While coolant is used to cool a motor inverter and a generator inverter included in a power drive unit configured to invert power between a battery and a motor/generator in both directions, an EV travel mode and a power generation travel mode are switched according to detection values from sensors in an electrically driven vehicle and including a switching device temperature sensor for a switching device of the inverters and a coolant temperature sensor, thereby controlling the vehicle. A failure of the coolant temperature sensor is detected according to a detection value from the coolant temperature sensor, and, in the EV travel mode, a detection value detected by the switching device temperature sensor for the switching device of the generator inverter is set as a detection value of a temperature of the coolant when the failure of the coolant temperature sensor is detected.