PMSM Variable Speed Drive Harmonic Cancellation for Chiller Compressors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Permanent magnet synchronous motors (PMSM) and their variable speed drives (VSDs) are limited in commercial and industrial HVAC&R systems due to low performance requirements, high system costs, and complex control system designs, particularly due to issues with harmonic currents generated by high-frequency switching, which lead to increased costs and volumes of passive filters.
Innovation Solution
The implementation of an active filter connected in parallel with the PMSM, which generates high-frequency currents of opposite polarity to cancel out harmonics, combined with a passive filter to absorb remaining harmonics, reducing heating effects on the rotor and optimizing cost and component size ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If passive filters are used to absorb switching harmonics, then harmonics are filtered, but the filter geometry becomes very large and system cost increases
Solution Approach 1:
The patent changes the operating parameters of the filter by switching between different capacitor bank configurations (series/parallel combinations) to adapt to different harmonic conditions and load requirements, optimizing filter performance while minimizing physical size
Solution Approach 2:
The filter system is made dynamic through automated switching of capacitor banks based on real-time harmonic detection and analysis, allowing the filter to adapt its characteristics rather than being a static oversized design
2Object-generated harmful factors
If passive filters are used to absorb switching harmonics, then harmonics are filtered, but system cost increases
Solution Approach 1:
The system optimizes cost by dynamically adjusting capacitor bank configurations to match actual harmonic needs, avoiding the cost of oversized fixed filters while maintaining effective harmonic suppression
Solution Approach 2:
The filter system includes automated control that detects harmonic conditions and self-adjusts the capacitor configuration without manual intervention, reducing operational costs and simplifying maintenance
3Power
If high frequency switching is used in power electronic devices, then power density increases, but harmonic currents increase causing heating effects
Solution Approach 1:
The patent converts the harmful high-frequency harmonic currents into a useful function by using them to drive the active filter capacitors, which then generate compensating currents to cancel the harmonics, effectively turning the problem into part of the solution
Solution Approach 2:
The active filter acts as an intermediary between the power electronic devices and the motor, capturing harmonics through its capacitors and injecting compensating currents to eliminate the harmful effects before they reach the motor
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively minimizes harmonic currents in the PMSM, reducing heating effects and optimizing system costs and component sizes, thereby enhancing the performance and efficiency of PMSM-based VSDs in HVAC&R systems.
Implementation Method 1
The active filter is arranged to generate high frequency currents having a magnitude and opposite polarity, with respect to the output AC power of the variable speed drive. The high frequency currents generated by active filter substantially cancel out high frequency currents flowing into the motor.
Implementation Method 2
A passive filter connected between the variable speed drive and the motor. The passive filter is arranged to absorb at least a portion of the high frequency currents generated remaining in the output AC power following cancellation by the active filter.
Implementation Method 3
A DC link is connected to the converter. The DC link filters and stores the DC voltage from the converter.
Data Source
AI summary
A drive system for a compressor of a chiller system includes a variable speed drive. The variable speed drive is arranged to receive an input AC voltage at a fixed AC input voltage and provide an output AC power at a variable voltage and variable frequency. The variable speed drive includes a converter connected to an AC power source providing the input AC voltage. The converter is arranged to convert the input AC voltage to a DC voltage. A DC link is connected to the converter. The DC link filters and stores the DC voltage from the converter. An inverter is connected to the DC link. A motor connectable to the compressor for powering the compressor. An active filter connected in parallel with the motor. The active filter is arranged to generate high frequency currents having a magnitude and opposite polarity, with respect to the output AC power of the variable speed drive. The high frequency currents generated by active filter substantially cancel out high frequency currents flowing into the motor.