Controlling systems with motor drives using pulse width modulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing PWM methods in HVAC and refrigeration systems cause significant mechanical vibrations due to resonance frequencies, leading to noise and potential damage, and existing solutions fail to account for or adjust these vibrations effectively.
Innovation Solution
A system that includes an electronic power converter and a controller, which determines and selects a PWM algorithm based on the harmonic signature to mitigate resonance frequencies, thereby reducing mechanical vibrations by avoiding frequency overlaps with the system's resonance frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If PWM is used to supply power efficiently, then power efficiency is improved, but mechanical vibrations increase due to resonance frequencies
Solution Approach 1:
The system dynamically selects PWM algorithms based on real-time detection of resonance frequencies. The controller monitors the mechanical system's response and adapts the PWM switching pattern to avoid resonant conditions, transforming a static PWM approach into a dynamic one that responds to changing operational conditions.
Solution Approach 2:
The system changes the PWM algorithm parameters (switching frequency, pulse width patterns) to avoid resonance frequencies. By modifying the harmonic content of the PWM signal through different algorithms, the system alters the excitation frequencies applied to the mechanical system, thereby avoiding resonant amplification of vibrations.
2Device complexity
If a fixed PWM algorithm is used, then control simplicity is maintained, but vibration mitigation capability is reduced
Solution Approach 1:
The control system is segmented into multiple discrete PWM algorithms, each with different harmonic characteristics. Instead of using a single complex adaptive controller, the system divides the control space into multiple predefined algorithms that can be selected based on detected resonance conditions, simplifying the overall control architecture while maintaining vibration mitigation capability.
Solution Approach 2:
The system implements feedback by monitoring mechanical vibrations and using this information to select appropriate PWM algorithms. The controller continuously detects resonance frequencies and adjusts the PWM algorithm selection accordingly, creating a closed-loop control system that automatically mitigates vibrations without requiring complex real-time computation.
3Manufacturing precision
If PWM switching frequency is increased to reduce ripple, then power quality is improved, but resonance excitation increases
Solution Approach 1:
The system uses periodic PWM switching patterns with carefully selected frequencies that avoid resonance. By implementing periodic control actions at multiple frequency components and selecting the optimal pattern based on resonance detection, the system maintains power quality while avoiding resonant excitation of mechanical components.
Data Source
AI summary
A system includes an electronic power converter and a controller. The electronic power converter supplies power to one or more motor drives of an HVAC and/or refrigeration system. The controller obtains a plurality of pulse width modulation (PWM) algorithms. Each PWM algorithm has an associated harmonic signature. The controller further determines one or more resonance frequencies associated with the HVAC and/or refrigeration system. The controller also selects a first PWM algorithm from the plurality of PWM algorithms based at least in part on the harmonic signature associated with the first PWM algorithm mitigating the one or more resonance frequencies associated with the refrigeration system. The controller further operates the electronic power converter according to the first PWM algorithm.