Power Conversion Control Device Surge Voltage Suppression
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Solution Overview
Problem
The existing power conversion control devices can generate surge voltages during the switching process of triangular waves, which poses a risk to the motor and drive circuit.
Innovation Solution
A power conversion control method and device that generate PWM signals for single-phase or multiphase bridge circuits connected to inductive loads, where the carrier wave switching is controlled based on pre-switching and post-switching pulse times, determining whether switching is enabled or disabled based on these times and threshold values to prevent surge voltage occurrence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If carrier wave switching is performed to adapt to different motor operating states, then the adaptability of the power conversion control device is improved, but surge voltage is generated during the switching process
Solution Approach 1:
The patent calculates pre-switching pulse time (from first conductive state switching timing to carrier wave switching timing) and post-switching pulse time (from carrier wave switching timing to second conductive state switching timing) before performing carrier wave switching. By evaluating these time intervals in advance and comparing them with threshold values, the system determines whether switching should be executed, thereby preventing surge voltage while maintaining adaptability to different motor operating states
Solution Approach 2:
The patent implements a feedback mechanism where the calculated pre-switching and post-switching pulse times are continuously compared with predetermined threshold values. Based on this comparison feedback, the system dynamically decides whether to enable or disable carrier wave switching, thus adapting the switching behavior to real-time conditions and preventing surge voltage generation
2Reliability
If carrier wave switching timing is optimized to suppress surge voltage, then the reliability of the power conversion system is improved, but the switching flexibility is reduced
Solution Approach 1:
The patent introduces threshold parameters (pulse time sum threshold value, individual pulse time threshold values) that define the conditions for enabling or disabling carrier wave switching. By adjusting these parameters, the system can control the switching behavior to suppress surge voltage while maintaining appropriate flexibility for different operating conditions
Data Source
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AI summary
Provided is a power conversion control method including: calculating a pre-switching pulse time being a time from a first conductive state switching timing being a conductive state switching timing of a second bridge circuit immediately before a predetermined carrier wave switching timing, to the carrier wave switching timing; calculating a post-switching pulse time being a time from the carrier wave switching timing to a second conductive state switching timing being an initial conductive state switching timing after the carrier wave switching timing; when a conductive state of the second bridge circuit is not switched at the carrier wave switching timing, determining that switching of the carrier wave is disabled when the sum of the pre-switching pulse time and the post-switching pulse time is less than a predetermined pulse time sum threshold value; and when the conductive state of the second bridge circuit is switched at the carrier wave switching timing, determining that the switching of the carrier wave is disabled when the pre-switching pulse time or the post-switching pulse time is less than a predetermined pulse time threshold value.