Model Predictive Control for Multi-Phase DC/DC Converters
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Solution Overview
Problem
Existing model predictive control methods for DC/DC converters face limitations in achieving high sampling rates and large prediction horizons due to the computational complexity of the optimization problem, leading to slow dynamic control and limited reaction to disturbances.
Innovation Solution
The optimization problem is divided into two subproblems for a model predictive output variable controller and a choke current controller, reducing the state space model from fourth-order to second-order and limiting the finite control set, allowing for faster solution finding and enabling larger prediction horizons with high sampling rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If model predictive control is implemented with large prediction horizons, then control accuracy and disturbance rejection are improved, but computational complexity increases exponentially
Solution Approach 1:
The patent segments the multiphase DC/DC converter into multiple independent single-phase equivalent circuits. Each phase is controlled separately with its own model predictive controller, allowing the overall control problem to be divided into smaller, computationally manageable subproblems while maintaining accurate control performance
Solution Approach 2:
The patent uses a simplified single-phase equivalent circuit model that copies the essential dynamics of each phase without requiring the full complex multiphase model. This reduced-order model enables faster computation while preserving the key control characteristics needed for accurate prediction
2Speed
If high sampling rates are used, then dynamic control response is improved, but the time required to solve the optimization problem decreases the available computation time
Solution Approach 1:
By dividing the multiphase converter control into independent single-phase segments, each optimization problem is solved separately and simultaneously. This parallelization approach reduces the total computation time required, enabling high sampling rates while maintaining adequate computation time for each phase's optimization problem
Solution Approach 2:
The patent changes the control parameters by using a reduced-order single-phase equivalent model with fewer state variables. This parameter reduction decreases the dimensionality of the optimization problem, allowing faster solution times that support high sampling rates
3Productivity
If the state space model order is reduced, then computational effort is decreased, but control precision may be compromised
Solution Approach 1:
The patent applies local quality by creating an equivalent single-phase model that captures the local dynamics of each phase independently. This localized modeling approach maintains sufficient precision for control purposes while reducing the overall system model order, enabling faster computation without significant loss of control accuracy
Data Source
AI summary
For an easily implementable method for model predictive control of a DC/DC converter, and a corresponding controller, with which the optimization problem of the model predictive control can also be solved sufficiently quickly with large prediction horizons, the optimization problem is divided into two optimization problems by a model predictive output variable control and a model predictive choke current control being implemented in the control unit (10), wherein: the strands of the multiphase DC/DC converter (12) for the output variable control are combined into a single strand; a time-discrete state space model is produced therefrom; and the output variable control predicts the input voltage (uv,k+1) of the next sampling step (k+1) for this single strand on the basis of a first cost function (Jv) of the optimization problem of the output variable control, said input voltage being given to the choke current control as a setpoint and the choke current control determining therefrom the necessary switch positions of the switches (S1, S2, S3, S4, S5, S6) of the strands of the multiphase DC/DC converter (12) for the next sampling step (k+1) on the basis of a second cost function (Ji) of the optimization problem of the choke current control.