Alternating PWM Inverter Control for Switching Loss Reduction
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Solution Overview
Problem
Existing pulse-width-modulated control methods for switching elements in pulse-controlled inverters often require halving the switching frequency by altering the modulation frequency or period duration, which can disrupt current control dynamics and require additional software adaptations, especially at high rotational speeds.
Innovation Solution
Implementing an alternately left-aligned and right-aligned pulse-width modulation method that halves the switching frequency by alternating the placement of impulses at the beginning and end of signal periods, while maintaining the modulation frequency and period duration, allowing for seamless switching between control modes without affecting software tasks or duty factor calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the modulation frequency is halved to reduce switching frequency, then switching losses and EMC radiation are minimized, but current control dynamics are disrupted and software adaptations are required
Solution Approach 1:
The patent implements periodic switching within each signal period by alternating between left-aligned and right-aligned impulse positions. This creates a periodic pattern that effectively halves the switching frequency while maintaining the original signal period duration, thereby reducing switching losses without disrupting current control dynamics
Solution Approach 2:
The patent changes the temporal position parameter of the control impulses within each signal period. By alternating between two specific positions (beginning and end of signal period), the system achieves frequency reduction while preserving the essential control characteristics needed for stable current dynamics
2Loss of energy
If the modulation frequency is halved to reduce switching frequency, then switching losses and EMC radiation are minimized, but additional software adaptations are required
Solution Approach 1:
The alternating alignment pattern creates a predictable periodic structure that can be implemented through simple conditional logic in software. The periodic nature allows existing software tasks to continue functioning without major adaptations, as the pattern repeats regularly within each signal period
Solution Approach 2:
The software is programmed in advance to recognize the alternating pattern and automatically adjust impulse positioning. This preliminary programming approach eliminates the need for complex runtime adaptations, as the switching frequency reduction is achieved through pre-planned alternating alignment rather than dynamic frequency changes
3Loss of energy
If the period duration is doubled to halve switching frequency, then switching losses are reduced, but the control signal frequency changes affecting system dynamics
Solution Approach 1:
The patent maintains the original signal period duration while implementing periodic switching within each period. By alternating impulse positions twice within each unchanged period, the effective switching frequency is halved without changing the fundamental control signal frequency, thus preserving system dynamics
Solution Approach 2:
The system dynamically adjusts the position of control impulses within each signal period based on an alternating pattern. This dynamic positioning allows the switching frequency to be reduced while the signal period remains constant, maintaining the speed and frequency characteristics required for proper system operation
Data Source
AI summary
A method is described for the pulse-width-modulated control of switching elements of a pulse-controlled inverter, the impulses of successive signal periods of the control signal, in a first control mode, respectively having a uniform start or end time within the signal period, or being situated uniformly centered in the middle of the signal period, and the impulses of successive signal periods of the control signal, in a second control mode, being situated alternately at the beginning of the signal period and at the end of the signal period.