Cycle-Skipper Phase Angle Shift for Harmonic Reduction
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Solution Overview
Problem
Cycle-skipping motor speed control systems produce undesirable harmonic components, leading to vibration, noise, and heating effects, especially when multiple cycle skippers are connected to a common source with temporally aligned firing patterns, which exacerbate these issues.
Innovation Solution
Implementing a phase angle shift in the firing patterns of multiple cycle skippers connected to a common source, allowing non-concurrent firings and optimizing the circuit architecture to reduce harmonic components, thereby minimizing undesirable effects on both the source and load sides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple cycle skippers are connected to a common source with temporally aligned firing patterns, then the motor speed control system can operate multiple loads efficiently, but the source current waveforms develop harmonic components of relatively higher amplitude, causing increased vibration, noise and heating effects
Solution Approach 1:
The patent applies periodic action by implementing phase angle shifting in the firing patterns of multiple cycle skippers. Instead of temporally aligned firings, each cycle skipper is assigned a different phase angle, creating a periodic distribution of current flow that spreads harmonic components across different time intervals, thereby reducing peak harmonic amplitudes and minimizing vibration, noise and heating effects.
2Use of energy by moving object
If cycle-skipping control is used to reduce motor speed, then energy consumption is reduced, but the current waveform becomes rich in harmonics causing vibration, noise and heating effects
Solution Approach 1:
The patent applies parameter changes by modifying the firing angle parameter of each cycle skipper. By varying the phase angle of each cycle skipper's firing pattern, the system maintains effective speed control while distributing current flow more evenly across the firing cycle. This parameter adjustment reduces the concentration of harmonic components at specific frequencies, thereby reducing vibration, noise and heating effects while preserving energy efficiency.
Data Source
AI summary
A method, computer-readable code, and controller are provided for controlling a cycle-skipping control system having at least one cycle skipper connected to a multi-phase AC (alternating current) power source to drive a variable frequency load. A respective firing sequence is generated to be applied to a plurality of power switches in the cycle skipper for implementing a desired mode of operation. The stream of pulses may be arranged to form a grouping of two or more closely adjacent pulses over a time interval, wherein each pulse grouping contributes a desired spectral power over the time interval, and further wherein each pulse grouping enables to spread the power over the time interval as compared to a single pulse having the desired spectral power, thereby reducing harmonic components in currents supplied by the power source.