Power Converter Control With DMA-Driven Variable-Frequency PWM
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Solution Overview
Problem
Conventional PWM signals have a fixed frequency, limiting their ability to generate periodically varying outputs, such as sinusoidal signals, which are required in applications like wireless power transfer, where the frequency modulation is not possible with existing technologies.
Innovation Solution
A controller that generates PWM signals with modulated repetition rate and frequency, using a generator module, memory tables, and a DMA module to write rise moment, fall moment, and repetition period values into registers, enabling flexible PWM, PFM, or hybrid PWFM control for power converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional PWM signals with fixed frequency are used, then the control structure is simple, but the ability to generate periodically varying outputs is limited
Solution Approach 1:
The patent implements dynamic frequency modulation by allowing the PWM repetition rate to vary over time according to a modulation signal. The PWM generator is configured to adjust the repetition rate based on a frequency modulation signal, enabling the system to generate periodically varying outputs while maintaining a relatively simple control structure through dedicated hardware support.
2Adaptability or versatility
If PWM repetition rate is modulated to enable frequency variation, then the ability to generate sinusoidal outputs is improved, but the hardware complexity increases
Solution Approach 1:
The patent employs lookup tables pre-stored in memory that contain predetermined PWM duty cycle values and repetition rate values corresponding to different phases of a sinusoidal cycle. The DMA controller automatically retrieves and loads these pre-calculated values into registers at the appropriate times, eliminating the need for complex real-time calculations and reducing hardware complexity while enabling accurate sinusoidal output generation.
Solution Approach 2:
The patent introduces a DMA (Direct Memory Access) controller as an intermediary component that bridges the memory storage and PWM generation functions. The DMA controller autonomously manages the transfer of modulation data from memory to the PWM generator registers, offloading the control processor from complex modulation calculations and simplifying the overall hardware architecture while enabling sophisticated frequency and duty cycle modulation.
3Adaptability or versatility
If lookup tables are used for PWM control, then the control flexibility is improved, but the memory resource requirements increase
Solution Approach 1:
The patent segments the lookup tables into separate memory structures: one table stores duty cycle values while another stores repetition rate values. This segmentation allows the system to load only the required portion of each table into separate registers (duty cycle register and repetition rate register), reducing the amount of memory that needs to be actively managed at any given time while maintaining full control flexibility through the combination of segmented tables.
Data Source
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AI summary
A controller for a power converter, and a method therefor are disclosed, comprising: a generator module configured to generate a sequence of pulses each having a width defined by a rise moment, R, and fall moment, F stored in respective RM and FM registers, the sequence of pulses having a repetition rate T that is modulated by a repetition period, RP, value stored in a RP register; a memory having a tables of R values, F values and RP values configured to be written into the generator module RM, FM and TM register respectively; a direct memory access, DMA, module for writing R, F and RP values from the respective memory table into the RM, FM, and TM registers respectively, in response to a DMA trigger; and a core coupled to the DMA module and configured to write the R, F and RP values into the memory table.