Electric Vehicle Controller LC Resonance Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing controllers for electrically powered vehicles can suppress LC resonance due to low-order frequencies but fail to effectively address resonance caused by high-order frequencies, such as the electrical 12th-order frequency, which can still occur when the electrical sixth-order frequency is raised.
Innovation Solution
A controller that switches between pulse-width modulation control and square wave control based on a modulation percentage, using specific switching patterns to suppress LC resonance in both low-order and high-order frequency regions, with different modes for each resonance region to manage the rotation speed of the motor and adjust the number of pulses and switching angles to reduce resonance and increase energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrical sixth-order frequency is raised to suppress LC resonance, then resonance due to low-order frequency is suppressed, but a component of higher-order frequency such as electrical 12th-order frequency increases causing LC resonance at high-order frequency
Solution Approach 1:
The patent applies parameter changes by switching between different control modes (PWM control and square wave control with different switching patterns) based on the modulation percentage and resonance region. When the modulation percentage indicates entry into a resonance region, the controller changes the switching pattern parameters to raise the problematic frequency component out of the resonance region, thereby suppressing LC resonance while managing high-order frequency components
Solution Approach 2:
The patent implements dynamics by dynamically switching between multiple control modes based on real-time operating conditions (modulation percentage and detected resonance region). The controller transitions between PWM control mode, first square wave control mode, and second square wave control mode depending on whether the system is in a resonance region and what type of resonance is occurring, allowing adaptive suppression of both low-order and high-order frequency resonance
2Reliability
If square wave control with three pulses per cycle is used to raise electrical sixth-order frequency, then LC resonance at sixth-order frequency is suppressed, but switching loss increases
Solution Approach 1:
The patent reduces switching loss by dynamically selecting the appropriate control mode based on operating conditions. When not in a resonance region, the controller uses standard PWM control or simple square wave control with lower switching frequency. Only when entering a resonance region does it switch to the three-pulse-per-cycle square wave control pattern, thereby minimizing switching loss while maintaining resonance suppression effectiveness
Solution Approach 2:
The patent changes switching pattern parameters adaptively based on the modulation percentage and resonance region detection. By adjusting the number of pulses per cycle and the switching angles according to the specific operating conditions, the controller optimizes the balance between resonance suppression capability and switching loss, using more aggressive switching patterns only when necessary
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A controller of an electrically powered vehicle (20) includes an electronic control unit (50). The electronic control unit (50) performs a switching control by a square wave control in a first switching mode when a rotation speed of the motor (32) is equal to or higher than a first predetermined rotation speed. The electronic control unit (50) performs the switching control by the square wave control in a second switching mode when the rotation speed of the motor (32) is lower than the first predetermined rotation speed. The first predetermined rotation speed is a rotation speed lower than a first resonance region. The first switching mode is a mode of a switching pattern that suppresses LC resonance in the first resonance region. The second switching mode is a mode of a switching pattern that suppresses LC resonance in a second resonance region lower than the first predetermined rotation speed.