Interleaved Variable Voltage Converter for Powertrain Ripple Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle powertrain systems face challenges in efficiently managing high voltage and current stresses, particularly during over current or short circuit conditions, which can lead to inefficiencies and increased losses in DC-DC converters used in electrified vehicles.
Innovation Solution
A bi-directional three-legged interleaved variable voltage converter is implemented, where two legs are modulated at a common frequency out of phase with each other, and the third leg is modulated at a higher frequency, combined with DC and AC inductors to reduce ripple current, and heterogeneous components like Si IGBTs and SiC MOSFETs are used to optimize current distribution and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If solid-state switches such as IGBTs are used in the DC-DC converter to meet voltage, current and switching requirements, then the converter can handle high voltage and current, but the components are subject to stresses including over current or short circuit conditions which increase losses and reduce efficiency
Solution Approach 1:
The DC-DC converter is divided into three parallel legs (first, second, and third legs) that share the total current. Each leg handles a portion of the current, reducing the stress on individual switches and lowering switching losses while maintaining the overall power handling capability of the converter.
Solution Approach 2:
The controller modulates the switches in different legs at different frequencies (interleaved switching). The first leg switches at a higher frequency while the second and third legs switch at a lower frequency, creating periodic current distribution that reduces peak switching losses and improves efficiency.
2Device complexity
If single frequency modulation is used in DC-DC converter legs, then the control is simple, but ripple current is higher and efficiency is reduced
Solution Approach 1:
The controller implements periodic modulation at different frequencies for different legs. The first leg is modulated at a frequency greater than twice that of the second and third legs, creating interleaved switching patterns that cancel ripple currents and reduce overall ripple while maintaining manageable control complexity.
3Ease of operation
If all legs are modulated at the same frequency, then the switching control is uniform and simple, but the ripple current is higher and switching losses increase
Solution Approach 1:
The system uses asymmetric modulation where the first leg switches at a different frequency (greater than twice) compared to the second and third legs. This asymmetric frequency distribution creates interleaved current waveforms that reduce ripple current and switching losses while maintaining ease of operation through coordinated control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the efficiency of voltage conversion, reduces ripple current, and lowers switching losses, thereby improving the overall performance and reliability of the powertrain system while minimizing noise and vibration issues.
Implementation Method 1
A bi-directional three-legged interleaved variable voltage converter is implemented, where two legs are modulated at a common frequency out of phase with each other, and the third leg is modulated at a higher frequency, combined with DC and AC inductors to reduce ripple current
Implementation Method 2
heterogeneous components like Si IGBTs and SiC MOSFETs are used to optimize current distribution and efficiency
Data Source
AI summary
A vehicle powertrain includes a direct-current (DC)-DC power converter and a controller. The DC-DC power converter includes first, second, and third legs in parallel, wherein the first leg is configured to carry a first DC current substantially equal to a sum of DC currents of the second and third legs. The controller may be configured to modulate switches of the first leg at a frequency greater than at least twice that of the second and third legs.