Multiple Active Bridge Converter Phase-Shift Control for Low-Power Losses
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Solution Overview
Problem
Existing methods for controlling multiple active bridge converters (MAB) face challenges in maintaining high efficiency at low power and optimizing phase shift values in real-time, with EPS modulation being inefficient at low power and the disturbance and observe method lacking optimal solutions.
Innovation Solution
The method involves scanning the internal phase shift of a port, computing the internal phase shift of a port, and external phase shifts, and updating the switching controls based on optimized values of internal and external phase shifts to minimize total losses and maximize zero-voltage switching (ZVS) conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If EPS modulation is used to control MAB converter, then the control system has a single solution and is simple to implement, but efficiency is not optimal at low power
Solution Approach 1:
The patent applies dynamics by making the internal phase shift adjustable and scanable rather than fixed at zero. The control method dynamically scans the internal phase shift value and selects the optimal value that minimizes total losses, transforming a static control parameter into a dynamic one that adapts to different operating conditions, particularly improving efficiency at low power levels.
Solution Approach 2:
The patent changes the parameter of internal phase shift from a fixed value (zero in EPS modulation) to a variable parameter that can be scanned and optimized. By varying the internal phase shift parameter and evaluating its impact on total losses, the system identifies the optimal setting for each operating condition, thereby resolving the contradiction between implementation simplicity and efficiency.
2Ease of manufacture
If disturbance and observe method is used to optimize internal phase shift, then implementation is simple, but the solution may not be optimal as it only considers RMS currents and conduction losses
Solution Approach 1:
The patent implements feedback by calculating total losses (including both conduction losses and switching losses) for each scanned internal phase shift value and using this feedback to identify the optimal value. The system continuously monitors and evaluates the impact of different phase shift values on overall system efficiency, not just RMS currents, creating a closed-loop optimization process that achieves higher precision.
Solution Approach 2:
The patent replaces the simple disturbance and observe approach with a more sophisticated evaluation method that substitutes comprehensive loss calculation (considering both conduction and switching losses) for the simpler RMS current measurement. This substitution of measurement and evaluation mechanisms enables more accurate optimization while maintaining computational feasibility.
3Loss of energy
If internal phase shift is scanned and optimized to minimize total losses, then efficiency is improved across operating range, but computation time and complexity increase
Solution Approach 1:
The patent applies partial action by scanning the internal phase shift over a limited range (from 0 to a maximum value) rather than evaluating all possible values. The method performs a targeted scan focusing on the relevant operating range, computing total losses at discrete points, and selecting the optimal value from this subset, thereby reducing computation time while still achieving efficient optimization.
Solution Approach 2:
The patent performs preliminary calculation of total losses (including both conduction and switching losses) for each candidate internal phase shift value before selecting the optimal one. By pre-computing and comparing the total loss values across the scan range, the system identifies the minimum loss point efficiently, preparing the optimal setting in advance for implementation, thus managing computation time effectively.
Data Source
AI summary
The invention relates to a method for controlling switches of a multiple active bridge converter, the method comprising the steps of: a) scanning between 0 and π of the value of the internal phase shift (α1) of a port, called reference port, and, for each value of the internal phase shift (α1) of the reference port, carrying out the following sub-steps of: a1) computing, for each of the n−1 ports different from the reference port, the internal phase shift (αi); a2) computing, for each of the n−1 ports different from the reference port, the external phase shift (φi); a3) computing a set of at least one power parameter comprising the total losses (Ptotal losses) of the converter and, optionally, the number of switches of the converter in the ZVS condition; a4) determining an optimized value of the internal phase shift (α1,OPT) of the reference port; b) updating the switching controls for the switches.