Inverter Zero-Crossing Control With Bipolar Modulation Switching
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Solution Overview
Problem
Existing power converters and inverters face challenges in preventing modulation signal loss near zero-crossing points, leading to distorted waveforms and reduced power output quality due to limitations in switching transistor dead time and minimum on time.
Innovation Solution
Implementing a control method that switches between unipolar and bipolar modulation signals based on threshold values, with the first threshold greater than or equal to the second threshold, to ensure effective signal transmission and minimize waveform distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If unipolar modulation is used for high modulation signals, then power output efficiency is improved, but modulation signal loss occurs at zero-crossing points
Solution Approach 1:
The patent applies dynamic modulation strategy by switching between unipolar and bipolar modulation modes based on the absolute value of the modulation signal. When the absolute value exceeds a threshold, unipolar modulation is used for high efficiency; when it falls below the threshold, bipolar modulation is used to prevent signal loss. This dynamic adaptation resolves the contradiction between efficiency and reliability.
Solution Approach 2:
The patent changes the modulation parameter (modulation mode) based on the signal amplitude parameter. By monitoring the absolute value of the modulation signal and comparing it with a threshold, the system dynamically adjusts the modulation type, thereby optimizing both power efficiency and signal transmission reliability under different operating conditions.
2Speed
If switching transistor dead time is reduced to improve response speed, then modulation signal transmission is improved, but minimum on time limitation causes signal loss
Solution Approach 1:
The patent changes the modulation parameter (modulation mode) based on the signal amplitude parameter. By monitoring the absolute value of the modulation signal and comparing it with a threshold, the system dynamically adjusts the modulation type, thereby optimizing both power efficiency and signal transmission reliability under different operating conditions.
Data Source
AI summary
A power converter and an inverter circuit control method. A modulation signal is output in a bipolar modulation scheme near a zero-crossing point of the modulation signal of an inverter circuit, to prevent some modulation signals from being lost due to reasons such as minimum on time and dead time of a switching transistor in the inverter circuit, and further prevent an output voltage of the inverter circuit from being distorted near the zero-crossing point. When a three-phase inverter circuit performs discontinuous pulse width modulation, a zero-crossing interval is prolonged, and distortion of the output voltage of the inverter circuit is more clear. In this case, quality of electric energy can be better improved by outputting the modulation signal in the bipolar modulation scheme.