Isolated DC-DC Converter Control for Motor Drive EMI Tuning
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Solution Overview
Problem
Existing DC-DC converters in motor drive applications face challenges in achieving electromagnetic compatibility (EMC) compliance while maintaining a target output voltage, particularly in cases with multiple isolated input and output voltages, and existing solutions are limited in adjusting EMI emission spectrum without hardware changes.
Innovation Solution
A system utilizing a pulse width modulation controller and a programmable device to control multiple isolated power supplies, where the programmable device is powered based on the first output voltage, allowing for dynamic control of EMI emission spectrum and precise voltage regulation through closed-loop feedback and galvanic isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If switching regulators operate in flyback or push-pull topologies to provide multiple isolated power supplies, then voltage regulation capability is improved, but EMI emissions increase making EMC compliance difficult
Solution Approach 1:
The patent implements dynamic switching frequency adjustment where the controller can vary the operating frequency of the switching regulators based on EMI conditions. This allows the system to move away from fixed resonant frequencies that cause peak emissions, enabling EMC compliance while maintaining voltage regulation through adaptive frequency selection.
Solution Approach 2:
The system changes key operating parameters including switching frequency and duty cycle to control EMI emissions. By dynamically adjusting these parameters, the controller can shift the EMI spectrum away from problematic frequencies while maintaining the required output voltage levels across multiple isolated power supplies.
2Object-generated harmful factors
If hardware is modified to adjust EMI emission spectrum, then EMI control capability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces physical hardware modifications with a programmable controller that uses software/firmware to adjust EMI characteristics. Instead of changing circuit topology or adding passive components, the system uses digital control to dynamically adjust switching frequency and duty cycle, achieving EMI spectrum control through code rather than hardware changes.
Solution Approach 2:
The system transitions from static hardware-based EMI filtering to dynamic controller-based EMI management. The programmable device can adaptively adjust operating parameters in real-time based on measured EMI conditions, providing flexible emission control without requiring complex hardware modifications or respinning of the power supply design.
3Adaptability or versatility
If multiple isolated power supplies are used in motor drive electronics, then system functionality is improved, but EMI interference between multiple supplies increases
Solution Approach 1:
The patent implements coordinated dynamic frequency adjustment across multiple isolated power supplies. The controller can assign different switching frequencies to different power supply modules or dynamically shift their frequencies to avoid overlapping EMI spectra. This frequency diversity approach reduces mutual EMI interference while maintaining the functionality of multiple isolated outputs.
Solution Approach 2:
The system applies localized EMI control strategies to each power supply module individually. Each isolated power supply can have its switching frequency and duty cycle independently optimized to minimize its specific EMI contributions while considering the overall system EMI landscape. This localized approach allows tailored frequency selection for each converter stage.
Data Source
AI summary
A system includes a pulse width modulation controller configured to control a first output voltage of a first power supply associated with the system. The first power supply is referenced to a first input ground associated with the system and the first output voltage is referenced to a first output ground associated with the system. The system includes a programmable device configured to configured to control a second output voltage of a second power supply associated with the system. The second power supply is referenced to a second output ground associated with the system. The programmable device is powered based on the first output voltage.