Inverter Switch Control Mode Selection for Thermal Management
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Solution Overview
Problem
High-voltage electric power systems in vehicles face inefficiencies due to power loss and thermal issues in inverters, which are not effectively managed by existing control methods that either reduce motor torque or introduce noise, limiting system performance and service life.
Innovation Solution
A method for controlling inverter switch modes based on the torque output of the electric machine and inverter cooling circuit temperature, dynamically selecting between PWM modes such as SV-PWM and D-PWM to optimize performance and prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional inverter control methods are used to prevent overheating, then inverter temperature is reduced, but motor torque capability is reduced
Solution Approach 1:
The patent implements dynamic selection between different PWM control modes (first PWM mode and second PWM mode) based on real-time operating conditions including temperature and torque demands. The controller dynamically switches control strategies rather than using a fixed mode, allowing optimal performance across varying operating conditions while preventing overheating.
Solution Approach 2:
The patent changes control parameters by selecting different PWM modes with distinct characteristics. The first PWM mode is selected under certain conditions while the second PWM mode is selected under other conditions, effectively changing the control parameters to balance temperature management and torque delivery without permanent system modifications.
2Temperature
If inverter cooling is increased to prevent overheating, then inverter temperature is reduced, but system efficiency is reduced
Solution Approach 1:
The controller dynamically adjusts the PWM mode based on real-time temperature and torque conditions, allowing the system to maintain high efficiency when possible while only activating cooling-intensive modes when absolutely necessary to prevent overheating.
Solution Approach 2:
By changing control parameters through mode selection rather than always using aggressive cooling, the system achieves temperature management with minimal energy loss, adapting the control strategy to match actual thermal demands.
3Measurement precision
If PWM switching frequency is increased to improve control precision, then control accuracy is improved, but noise increases
Solution Approach 1:
The system dynamically selects between PWM modes based on operating conditions, using higher frequency modes when precision is critical and lower frequency modes when noise reduction is prioritized, creating an adaptive noise-control strategy.
Solution Approach 2:
The patent changes PWM control parameters including switching frequency and duty cycle patterns depending on the selected mode, allowing optimization of the noise-control balance by adjusting these parameters rather than maintaining fixed high-frequency operation.
4Device complexity
If inverter switch control mode is fixed to simplify control, then control complexity is reduced, but system adaptability is reduced
Solution Approach 1:
The controller implements dynamic mode selection that automatically adapts to varying operating conditions including temperature, torque demands, and speed ranges, providing high adaptability through a relatively simple decision framework that selects between predefined control modes.
Solution Approach 2:
The control system achieves multi-functionality by using a single controller that can operate in multiple PWM modes, allowing one control system to handle diverse operating conditions (different temperatures, torque levels, speeds) without requiring separate specialized controllers for each condition.
Data Source
AI summary
An inverter electrically connected to an electric machine is described. A method for controlling switching in the inverter includes determining a torque output of the electric machine and determining a temperature related to an inverter cooling circuit. A preferred inverter switch control mode for controlling the inverter is selected based upon the torque output of the electric machine and the temperature related to the inverter cooling circuit.