PWM Inverter Control with Decoupled Regulation and Modulation
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Solution Overview
Problem
Existing motor controllers face limitations in increasing the maximum switching frequency without corresponding increases in computational abilities, which affects the accuracy of voltage waveforms at higher fundamental frequencies.
Innovation Solution
The motor controller decouples the current regulator and modulation routines, executing them at different update rates. The current regulator operates at a first update rate, while the modulation routine operates at a second, higher update rate, with the latter being at least twice the frequency of the former. Additionally, the modulation routine is implemented in dedicated hardware to reduce computational load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the switching frequency is increased to improve voltage waveform accuracy, then the voltage waveforms more closely approximate sinusoidal waveforms, but the computational demands increase proportionally
Solution Approach 1:
The patent segments the control architecture into two distinct components: a current regulator operating at a lower update rate and a modulation routine operating at a higher switching frequency. This segmentation allows the computational burden to be distributed, with the current regulator performing complex calculations less frequently and the modulation routine performing simpler calculations at the higher frequency needed for accurate voltage waveforms.
Solution Approach 2:
The current regulator performs preliminary calculations to determine voltage references at a lower update rate, and these results are then reused by the modulation routine at the higher switching frequency. This preliminary action avoids redundant computations at each switching cycle while maintaining waveform accuracy.
2Manufacturing precision
If the current regulator update frequency is increased to improve control accuracy, then the voltage waveforms more closely approximate sinusoidal waveforms, but the device complexity increases
Solution Approach 1:
The patent divides the controller into functionally distinct segments: a current regulator operating at a lower update rate for complex calculations and a modulation routine operating at a higher frequency for waveform generation. This segmentation reduces the computational requirements at each segment, allowing implementation with simpler, lower-cost hardware while maintaining overall control accuracy.
3Manufacturing precision
If the switching frequency is increased to reduce voltage ripple, then the voltage waveforms more closely approximate sinusoidal waveforms, but the loss of energy increases
Solution Approach 1:
By segmenting the control into a lower-frequency current regulator and a higher-frequency modulation routine, the patent achieves accurate voltage waveforms and reduced voltage ripple without requiring the entire control system to operate at the high switching frequency. This reduces the computational energy consumption while maintaining waveform quality.
Data Source
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AI summary
A motor controller executing a current regulator and a modulation routine in separate update intervals provides an improved fundamental voltage waveform for a motor controlled by the motor controller. The current regulator is executed at a first periodic update rate and the modulation routine is executed at a second periodic update rate, where the frequency at which the modulation routine executes is at least twice the frequency at which the current regulator executes. Executing the current regulator and the modulation routines at different frequencies results in the current regulator generating a single voltage reference signal for multiple periods of the modulation routine. To reduce voltage ripple induced by decoupling execution of the current regulator and the modulation routine, the motor controller extrapolates the voltage reference generated by the current regulator into multiple voltage reference signals, where a unique voltage reference signal is provided for each period of the modulation routine.