MIMO Voltage Converter Control for Coupled Output Regulation
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Solution Overview
Problem
Existing voltage converter technologies fail to effectively manage multiple output voltages from a single voltage source due to inherent coupling between voltage outputs, which is not adequately addressed by single input single output (SISO) models and control methods.
Innovation Solution
A multiple input multiple output (MIMO) system using generalized Cuk-Middlebrook state-space averaging is employed to model and regulate all output voltages, incorporating a control vector and MIMO control methods to manage duty ratios and output voltages in boost and buck-boost converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If SISO control methods are used to manage multiple output voltages, then the control system is simpler, but the coupling between voltage outputs cannot be effectively addressed
Solution Approach 1:
The patent segments the control of multiple output voltages by introducing separate control loops for each output voltage. Each control loop independently regulates its respective output voltage while the coupled inductor current is shared among all outputs. This segmentation allows each output to be controlled with SISO-like simplicity while still addressing the coupling through the shared inductor.
Solution Approach 2:
The patent introduces an intermediary coupled inductor that mediates the coupling between multiple output voltages. The inductor current serves as an intermediate variable that links all output voltages together, allowing the control system to manage the coupling effect through a single shared energy storage element rather than direct voltage-voltage coupling.
2Ease of operation
If independent feedback loops are used for each output converter, then each output can be controlled independently, but the inherent coupling between voltage outputs is not properly accounted for
Solution Approach 1:
The patent implements feedback control for each output voltage through its dedicated control loop. Each loop measures its output voltage and adjusts the duty cycle of its switching element to maintain the desired voltage level. The feedback mechanism allows independent control of each output while the shared inductor naturally handles the coupling through its magnetic energy storage and transfer.
Solution Approach 2:
The patent changes the control parameter from direct voltage-voltage coupling control to inductor current-based control. By controlling each output through its relationship with the shared inductor current rather than directly through other output voltages, the system accounts for coupling effects through the inductor's magnetic coupling properties rather than electrical voltage coupling.
3Extent of automation
If a single controller is used for multiple output converters, then the system is more integrated, but the control of duty cycles becomes more complex
Solution Approach 1:
The patent segments the single controller into multiple independent control loops, each responsible for one output voltage. This segmentation allows the controller to manage multiple outputs through simple, modular control algorithms rather than a complex monolithic control strategy. Each loop operates independently with its own error amplifier and PWM generator.
Solution Approach 2:
The patent creates a universal control architecture where each control loop uses the same basic structure and components (error amplifier, PWM generator, switching element) to control different output voltages. This multi-functional approach allows a single controller IC to handle multiple outputs through replicated control modules rather than requiring different control strategies for each output.
Data Source
AI summary
An apparatus and method is presented for implementing and controlling a voltage converter with one input voltage and multiple output voltages. In the case of boost and buck-boost converters, a converter circuit with one inductor and a switched group of parallel connection capacitors is realized, one parallel connection for each output voltage. A duty ratio is monitored for the inductor and the switched group of capacitors to provide a set of duty ratios. The duty ratios form a control vector which describes the control inputs. The output voltages are the control outputs describing a MIMO system. A generalized Cuk-Middlebrook modeling approach is applied to the voltage converter, along with linearization and MIMO control methods to regulate all output voltages to desired levels.