Inverter Switching Frequency Control for EV Overtemperature Prevention
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Solution Overview
Problem
The over-temperature state of inverters and motors in electric vehicles affects energy consumption and normal operation, posing a safety risk.
Innovation Solution
Adjusting the switching frequency of the inverter based on operating points, temperature, and efficiency considerations to prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the switching frequency of the inverter is increased to improve motor performance and reduce electromagnetic interference, then the inverter and motor are more likely to enter an over-temperature state, which increases energy consumption and may affect normal operation and safe driving
Solution Approach 1:
The patent implements dynamic adjustment of the inverter's switching frequency based on real-time operating conditions (motor speed, torque, temperature). The control method transitions from a fixed switching frequency to a variable one that adapts to different operating points, allowing the system to optimize performance while preventing overheating by reducing switching frequency when temperature thresholds are approached
Solution Approach 2:
The patent changes the switching frequency parameter of the inverter based on the operating point of the motor. By establishing a correspondence between motor operating points (speed-torque characteristics) and optimal switching frequencies, the system dynamically adjusts the switching frequency to maintain motor performance while avoiding over-temperature conditions that would increase energy consumption
2Loss of energy
If the switching frequency is adjusted to avoid over-temperature states, then energy consumption is reduced and normal operation is ensured, but the complexity of the control system increases
Solution Approach 1:
The patent implements a feedback control mechanism where the switching frequency is continuously adjusted based on the motor's operating point and temperature conditions. The control system monitors motor speed and torque to determine the operating point, then adjusts the switching frequency accordingly, creating a closed-loop system that reduces energy consumption while maintaining simplicity through rule-based adjustment
Data Source
Figure 1a(a)~1a(f)
Figure 1b~2
Figure 3a~3b
AI summary
This application provides a method for adjusting a switching frequency of an inverter, a power assembly system, and an electric vehicle, and relates to the field of electric vehicles. A current output by the inverter is used to drive rotation of a motor. The method includes: first, obtaining a first operating point of the motor in operation, where the first operating point includes torque and a rotation speed; then, determining, based on a determined correspondence between an operating point and a switching frequency, a first switching frequency corresponding to the first operating point; and finally, adjusting a current switching frequency of the inverter to the first switching frequency. In this application, an over-temperature state of the motor and the inverter can be avoided.