Multiphase Power Converter Dynamic Current Set Point Scaling
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Solution Overview
Problem
Multiphase power converters face issues with increased coarseness of current set points as the number of cells rises, leading to higher jitter in pulse width modulation and output noise, due to discrete set point jumps and reduced control resolution.
Innovation Solution
A multiphase power converter system with a scaled current set point modulation scheme, where each cell receives a modified current set point signal, processed based on the number of cells, to control the power stage and reduce output noise, utilizing a voltage loop compensator and current loop compensator to enhance resolution and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the number of cells in a multiphase power converter is increased, then the power handling capability and fault tolerance are improved, but the current set point resolution deteriorates due to discrete set point jumps
Solution Approach 1:
The patent applies dynamics by making the current set point calculation adaptive rather than static. The control logic dynamically adjusts the current set point for each cell based on real-time parameters including the number of active cells, cell index, and measured output current. This dynamic calculation (Iset_cell = (Iset_converter + (cell_index - 1))/N_active_cells) ensures continuous resolution regardless of the number of cells, resolving the contradiction between power handling capability and control precision.
2Reliability
If the number of cells in a multiphase power converter is increased, then the fault tolerance is improved, but the control resolution deteriorates due to reduced granularity in current distribution
Solution Approach 1:
The control system dynamically adapts to the number of active cells N_active_cells in the fault tolerance calculation. When cells are deactivated due to faults, the control logic automatically recalculates the current set points for remaining active cells, maintaining precise control resolution. This dynamic reconfiguration ensures that control granularity is preserved regardless of how many cells are actively contributing to power output.
Solution Approach 2:
The patent implements feedback by continuously monitoring the actual output current from each cell and comparing it against the calculated set point. The control logic uses this feedback to adjust PWM duty cycles in real-time, ensuring that each active cell operates at its precise target current. This closed-loop feedback mechanism maintains high control resolution even as the number of active cells changes due to faults or load conditions.
3Power
If passive components in a single converter are made larger to handle higher power, then the power capacity is improved, but the parasitic elements increase leading to higher noise voltage
Solution Approach 1:
The patent applies segmentation by dividing a single high-power converter into multiple parallel converter cells. Each cell handles a portion of the total power, allowing the use of smaller passive components (inductors and capacitors) in each cell compared to a single converter handling the full power. This segmentation reduces the parasitic elements in each cell, thereby reducing the noise voltage generated by each cell while maintaining the total power capacity of the system.
Data Source
AI summary
A method for controlling a power converter that includes a first cell having an output connected at a first node in parallel with a second cell includes sensing a voltage signal at the first node, defining a current set point associated with the converter, processing the current set point associated with the converter to define a current set point associated with the first cell, sensing a current output by the first cell, controlling the first cell such that the first cell outputs a current substantially similar to the current set point associated with the first cell, processing the current set point associated with the converter to define a current set point associated with the second cell, sensing a current output by the second cell, and controlling the second cell such that the second cell outputs a current substantially similar to the current set point associated with the second cell.