Multi-Phase PWM Frequency Switching Without Phase Discontinuities
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Solution Overview
Problem
Existing pulse width modulation (PWM) technologies experience discontinuities and errors during frequency changes, leading to adverse effects such as overvoltage and oversaturation in circuits, due to improper phase shifts and threshold adjustments.
Innovation Solution
A method is introduced to generate PWM signals by employing a master control counter and a slave control counter with a phase delay, where the transition period is extended to ensure the slave counter reaches the minimum value at the new phase delay count, thereby avoiding discontinuities and maintaining accurate edge thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If frequency changes are implemented in PWM control, then adaptability is improved, but discontinuities and errors occur during transitions
Solution Approach 1:
The patent applies preliminary action by extending the transition period before the actual frequency change occurs. The slave counter is given additional time to complete its counting cycle and reach the minimum value at the new phase delay count, ensuring that the frequency transition happens smoothly without discontinuities or errors in the PWM signal generation.
2Adaptability or versatility
If phase delay is adjusted during frequency transitions, then adaptability is improved, but overlong PWM periods occur
Solution Approach 1:
The patent applies preliminary action by preparing the phase delay adjustment in advance during the extended transition period. The slave counter is allowed to complete its counting cycle first, and only then is the new phase delay applied. This ensures that phase delay adjustments do not cause overlong PWM periods, as the transition is smoothed out beforehand.
3Reliability
If transition period is extended, then reliability is improved, but productivity decreases
Solution Approach 1:
The patent applies partial or excessive action by extending the transition period only for the slave counter, while the master counter continues its normal operation. This partial extension is sufficient to ensure reliable frequency transitions without unnecessarily delaying the overall PWM control system, thus maintaining productivity while improving transition smoothness.
Data Source
AI summary
In described examples, a method of generating a pulse width modulation (PWM) signal includes repeatedly master control counting, by a master control counter generator, which includes one or both of incrementing and decrementing a master control counter with a minimum value and a maximum value, and repeatedly slave control counting with a phase delay with respect to the master control counting, and during a transition period, slave control counting to a new maximum value or a new phase delay. A maximum count of the transition period is selected to result in the transition period reaching the minimum value at the new phase delay count. The PWM signal is generated by generating rising edges when the slave control counter reaches a rising edge threshold, and generating falling edges when the slave control counter reaches a falling edge threshold.