Dual Three-Phase Machine Common-Mode Noise Reduction
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Solution Overview
Problem
Elevator power systems face significant challenges with common-mode (CM) electromagnetic interference (EMI) noise, which can damage motor bearings and windings, and existing solutions like CM filters are not viable due to weight penalties.
Innovation Solution
A dual-three-phase machine with two three-phase inverters is employed, eliminating the need for coupling inductors and using winding self-inductance to control circulating currents, thereby minimizing CM noise and eliminating common-mode voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If CM filters are added to attenuate CM noises, then CM noise attenuation is improved, but system weight increases significantly
Solution Approach 1:
The invention extracts and eliminates the source of common-mode noise by using a dual-three-phase machine configuration with two independent three-phase inverters. Each inverter drives one set of three-phase windings, and the combined output produces negligible common-mode voltage, thereby removing the need for CM filters and avoiding the weight penalty associated with them.
Solution Approach 2:
The invention converts the potential harm of CM noise into a benefit by designing a dual-three-phase system where the two three-phase sets work in conjunction to cancel out common-mode voltages. The harmful CM noise problem is transformed into a design feature where the system inherently produces negligible CM voltage, eliminating the need for additional filtering components.
2Productivity
If power electronics inverters are used to improve power system performance, then system performance is improved, but EMI noise problems increase
Solution Approach 1:
The invention segments the single three-phase inverter system into two independent three-phase inverters, each driving a separate set of windings. This segmentation allows independent control of switching patterns, enabling the system to maintain high performance while reducing EMI noise through coordinated operation of the two inverters.
Solution Approach 2:
The dual-three-phase machine acts as an intermediary between the power electronics inverters and the motor load. The unique winding configuration and control strategy of the dual-three-phase system mediate the switching actions of the inverters, transforming the harmful EMI noise into beneficial torque production while maintaining high performance.
3Reliability
If coupling inductors are used in paralleled inverter systems, then circulating current control is improved, but device complexity and weight increase
Solution Approach 1:
The dual-three-phase machine windings themselves provide the circulating current control function that would otherwise require external coupling inductors. The inherent inductance of the windings and the coordinated control of the two three-phase inverters enable the system to self-regulate circulating currents without additional passive components, reducing complexity and weight.
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 approach significantly reduces CM EMI noise and current, prevents damage to motor insulation and bearings, increases power density by eliminating CM filters and coupling inductors, and improves fault-tolerant capabilities.
Implementation Method 1
the first and second windings groups can have an identical back-electro-magnetic-force for each winding pair
Data Source
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AI summary
A system and/or method for controlling a dual-three-phase machine (500) with respect to a power electronics inverter (505) is provided. The dual-three-phase machine includes six phase windings (al, a2, b1, b2, c1, c2) divided into at least two windings groups configured to provide a combination of six voltages that achieve zero common-mode voltage and a significantly reduced common-mode noise current.