Inverter Control Synchronizes Phase Voltages to Reduce Noise
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Solution Overview
Problem
Existing power conversion devices fail to effectively reduce electromagnetic noise across a wide range of driving conditions, with previous methods either having limited effectiveness or decreasing performance as the modulation factor increases.
Innovation Solution
A power conversion device with a control system that synchronizes the rising and falling times of terminal voltages between phases by adjusting the carrier frequencies, allowing for effective reduction of electromagnetic noise through triangular wave comparison PWM and switching signal manipulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a noise filter composed of passive elements is used to reduce electromagnetic noise, then electromagnetic noise is reduced, but the space occupied by the power converter and cost increase
Solution Approach 1:
The patent extracts and eliminates the need for passive noise filters by using active control methods. Specifically, it adjusts the phase of the carrier signal to control switching elements, thereby reducing electromagnetic noise through control strategies rather than passive filtering components.
Solution Approach 2:
The patent replaces the mechanical/passive noise filter system with an active control system that uses carrier phase adjustment and switching element control to achieve noise reduction, substituting physical filtering with electronic control.
2Object-affected harmful factors
If the carrier phase is adjusted to reduce electromagnetic noise, then electromagnetic noise is reduced, but the effect is limited when voltage command is substantially zero
Solution Approach 1:
The patent implements dynamic control by continuously adjusting the carrier phase based on real-time switching states and terminal voltage conditions. The control method adapts to varying operating conditions including different voltage commands and modulation factors, maintaining noise reduction effectiveness across a wide range of driving conditions.
Solution Approach 2:
The patent uses feedback control by monitoring terminal voltage variations and switching states, then adjusting the carrier phase accordingly. This closed-loop approach ensures effective noise reduction regardless of the voltage command level or modulation factor, as the control continuously adapts to current operating conditions.
3Object-affected harmful factors
If terminal voltage variation between phases is canceled to reduce neutral point potential variation frequency, then electromagnetic noise reduction effect increases, but the method is only effective when voltage command is substantially zero
Solution Approach 1:
The patent employs dynamic carrier phase adjustment that adapts to different modulation factors and voltage command levels. By continuously optimizing the phase relationship between carriers based on real-time operating conditions, the method maintains its ability to reduce neutral point potential variation frequency and electromagnetic noise across all driving conditions, not just when voltage command is zero.
Data Source
AI summary
Switching control of an inverter is performed such that rising and falling of a terminal voltage of U phase including upper and lower arm switching elements are calculated, and the calculated rising of the terminal voltage of U phase and falling of a terminal voltage of V phase or W phase or the calculated falling of the terminal voltage of U phase and rising of the terminal voltage of V phase or W phase are synchronized with each other.