EV Motor Inverter Control for 6n-Order Ripple Cancellation
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Solution Overview
Problem
Existing control devices for electric vehicles do not effectively reduce frequency components that are multiples of the electric frequency, particularly in the power supply current and motor torque ripples, despite reducing switching frequency components.
Innovation Solution
A control device for electric vehicles that includes a DC power supply, a three-phase AC motor, an inverter, and a control unit, which corrects the input voltage by adding specific distortion components to cancel out high frequency components, such as the (6n−1)-th and (6n+1)-th order distortions, to reduce power supply current and motor torque ripples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If distortion components are added to cancel high frequency components, then power supply current and motor torque ripple are reduced, but control complexity increases
Solution Approach 1:
The control device employs feedback by continuously monitoring the input voltage to detect high frequency components and using this information to adjust the distortion components added to the voltage command. The control unit calculates the magnitude and phase of the detected high frequency components and dynamically adjusts the cancellation distortion components accordingly, creating a closed-loop control system that automatically adapts to changing operating conditions without requiring complex manual tuning.
2Object-affected harmful factors
If hardware changes are made to reduce ripple, then ripple reduction effectiveness improves, but device complexity and cost increase
Solution Approach 1:
The invention substitutes mechanical/hardware-based ripple reduction methods with an electrical control-based solution. Instead of modifying the physical structure of the inverter or motor to reduce ripple, the control device uses signal processing and distortion component injection to achieve ripple cancellation. This replaces potential hardware changes with software-based control algorithms, maintaining hardware simplicity while achieving effective ripple reduction.
Data Source
AI summary
A control device for an electric vehicle, includes: a DC power supply; a three-phase AC motor; an inverter that converts DC power supplied from the DC power supply into AC power and outputs the AC power to the three-phase AC motor; and a control unit that controls the inverter to control an input voltage to the three-phase AC motor. Further, when a parameter correlated with the input voltage includes a predetermined high frequency component, the control unit performs correction of adding a component for canceling out the high frequency component to the input voltage, and controls the three-phase AC motor based on the corrected input voltage.