Matrix Converter MPC with Load Current Estimation
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Solution Overview
Problem
Existing matrix converter systems operating in current control mode require costly or bulky current sensors to track output voltage or current, as they do not effectively model or predict load current, limiting their ability to minimize losses.
Innovation Solution
A matrix converter system that uses model predictive control (MPC) to estimate load current without a current sensor, selecting switching states in the switching matrix to minimize errors between output voltage and current references, using a multi-objective function that includes terms for voltage and current errors, and employs an observer to estimate load current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional control methods are used with current sensors to track output voltage or current, then measurement accuracy is improved, but device cost and complexity increase due to costly or bulky current sensors
Solution Approach 1:
The patent creates a mathematical model (copy) of the load current behavior based on the known switching states and circuit parameters. Instead of directly measuring the physical current with sensors, the system uses the electrical circuit model to calculate and predict load current, replacing the need for physical current sensors while maintaining measurement accuracy.
Solution Approach 2:
The patent replaces the mechanical/electrical current sensing system with an electrical/mathematical modeling system. By substituting physical sensors with computational models that calculate current based on circuit equations and switching states, the system eliminates bulky hardware while achieving the same measurement function.
2Device complexity
If model predictive control is implemented without load current information, then device complexity is reduced, but control precision deteriorates due to inability to track output voltage or current effectively
Solution Approach 1:
The patent performs preliminary calculation of load current using the electrical circuit model before the actual control action is taken. By predicting the load current in advance based on current switching states and circuit parameters, the system has the necessary current information ready for the MPC algorithm, enabling precise control without requiring physical sensors.
Solution Approach 2:
The patent implements a feedback mechanism where the calculated load current from the electrical circuit model is fed back into the MPC controller. This feedback loop allows the controller to continuously adjust switching states based on the predicted current, maintaining precise tracking of output voltage and current references despite eliminating physical current sensors.
3Loss of energy
If electrical circuit modeling is used to estimate load current, then loss minimization is improved through better control, but calculation complexity increases due to mathematical modeling requirements
Solution Approach 1:
The patent changes the approach from direct physical measurement to mathematical parameter calculation. By using electrical circuit parameters (resistances, inductances, capacitances) and switching states as inputs to calculate load current, the system achieves energy loss minimization through precise control while the computational complexity remains manageable due to the use of standard circuit equations.
Data Source
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AI summary
A matrix converter system operating in current control mode is provided. The matrix converter (102) includes a switching matrix coupled between a low voltage side and a high voltage side, wherein the matrix converter is coupled at its low voltage side to a generator (104) for receiving an input power including an input current and transforming the input power into an output power at its high voltage side, wherein a load is coupled to the high voltage side. The control system includes a load observer (214) and a model predictive controller (MPC) (212). The load observer is configured to estimate a load current that flows to the load from the high voltage side of the matrix converter as a function of a switching state of the switching matrix, an output voltage output at the high voltage side of the matrix converter, and the input current.. The MPC is configured to select the switching state of the switching matrix to meet one or more control objectives defined by minimization of a multi-objective function that tracks the output voltage and the input current using the estimated load current.