Inverter Torque Control via Coolant Temperature Feedback
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Solution Overview
Problem
Current hybrid-electric and full-electric vehicles face limitations in extending motor torque capabilities across a range of inverter coolant temperatures, leading to electrical overstress and hardware derating, which affects performance and durability.
Innovation Solution
Implementing high-voltage electrical system control logic with closed-loop feedback and pulse width modulation techniques to dynamically adjust motor torque limits based on inverter coolant temperature, DC bus current, and voltage, allowing for real-time optimization of torque output within thermal and electrical limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If motor torque capabilities are extended across a range of inverter coolant temperatures, then motor torque and power output are improved, but electrical overstress and hardware durability are worsened
Solution Approach 1:
The patent implements dynamic adjustment of motor torque limits based on real-time inverter coolant temperature measurements. The control system continuously monitors temperature and adjusts the maximum allowable torque output accordingly, transitioning from static torque limits to dynamic, condition-based limits. This allows the motor to operate at higher torque levels when cooling is adequate while preventing electrical overstress when thermal conditions deteriorate.
Solution Approach 2:
The patent employs closed-loop feedback control where the inverter coolant temperature sensor provides continuous feedback to the control system. This feedback enables the controller to adjust motor torque limits in real-time based on actual thermal conditions, creating a self-regulating system that balances performance output with hardware protection. The feedback mechanism ensures that torque limits are continuously optimized based on measured temperature data.
2Reliability
If hardware is derated to prevent electrical overstress, then hardware durability is improved, but motor torque capabilities and performance are worsened
Solution Approach 1:
Instead of applying static hardware derating that permanently limits torque capabilities, the patent implements dynamic torque limit adjustment that adapts to real-time thermal conditions. When inverter coolant temperature is within safe operating ranges, the system allows maximum torque output without derating. Derating is applied dynamically only when temperature conditions require it, minimizing performance impact while maintaining hardware durability.
Solution Approach 2:
The patent changes the operational parameters of the motor control system by adjusting torque limits as a function of inverter coolant temperature. Rather than maintaining a fixed, conservative torque limit that would unnecessarily restrict performance, the system varies the torque parameter dynamically based on measured temperature, allowing optimal performance when conditions permit while protecting hardware when conditions deteriorate.
3Reliability
If torque limits are constrained by thermal limits, then hardware protection is improved, but real-time optimization of torque output is worsened
Solution Approach 1:
The patent implements a feedback-based control system that uses real-time inverter coolant temperature measurements to dynamically adjust torque limits. This feedback mechanism enables continuous optimization of torque output based on actual thermal conditions rather than relying on conservative pre-set limits. The system processes temperature data and adjusts torque commands in real-time, maintaining both hardware protection and performance optimization.
Solution Approach 2:
The control system performs self-service by automatically adjusting torque limits based on its own measurement of inverter coolant temperature. The system monitors its own thermal conditions and autonomously modifies its output characteristics without external intervention, enabling real-time optimization that responds immediately to changing thermal conditions while maintaining hardware protection.
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 enhances motor torque and power capabilities, decouples electrical stress from mechanical stress, and balances performance with hardware durability and efficiency, while reducing the need for hardware downsizing and cost.
Implementation Method 1
employing the PIM to transform battery-generated direct current (DC) power to motor-driving AC power using pulse-width modulated control signals output from the PCM
Implementation Method 2
A high-frequency bulk capacitor may be arranged across the positive and negative rails of the main DC bus to provide electrical stability and store supplemental electrical energy
Implementation Method 3
contemporary traction battery packs group stacks of lithium-ion, lead-acid, or nickel-based battery cells into individual battery modules that are mounted onto the vehicle chassis
Data Source
AI summary
Presented are high-voltage electrical systems, control logic, and electric-drive vehicles with optimized motor torque output. A method of operating an electric-drive vehicle includes a controller identifying the vehicle's operating mode and determining calibration settings corresponding to this operating mode. These calibration settings include low and high coolant temperature (CoolTemp) thresholds, and motor-calibrated torque limits as a function of CoolTemp. The controller determines if the present CoolTemp of the power inverter's coolant is greater than the low CoolTemp threshold and less than the high CoolTemp threshold. If so, the controller sets a motor torque limit of the vehicle's electric motor to a torque limit value selected from a fixed torque limit region within the torque limits data between the low and high CoolTemp thresholds. The controller operates the power inverter to regulate the transfer of electrical power between a rechargeable battery and the electric motor based on the motor torque limit.