Stator Coil Configuration for Voltage Surge Prevention
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Solution Overview
Problem
Electric rotating machines experience voltage surges when using square wave voltages, leading to increased phase-to-phase voltage and potential short circuits due to resonant frequency issues with harmonic components, necessitating increased insulation thickness to prevent short circuits.
Innovation Solution
The stator coil configuration is modified by using n circumferentially-consecutive single-phase slots per magnetic pole, with sections of the phase windings received in different slots to minimize negative mutual inductance, reducing resonant frequency and resonance peak, and thereby lowering the maximum phase-to-phase voltage, which in turn shortens the necessary phase-to-phase clearance for electrical insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stator coil uses conventional winding configuration with first and last sections received in the same single-phase slots, then the manufacturing process is simpler, but the negative mutual inductance increases causing higher resonant frequency and voltage surges
Solution Approach 1:
The patent divides the phase winding into multiple sections (first section and kth section) and receives them in different single-phase slots rather than the same slot. This segmentation reduces the negative mutual inductance between sections, lowering the resonant frequency and preventing voltage surges while maintaining manufacturing feasibility
2Reliability
If the insulation thickness is increased to prevent short circuits from voltage surges, then the electrical insulation reliability improves, but the phase-to-phase clearance increases reducing the machine's power density
Solution Approach 1:
The patent applies preliminary anti-action by modifying the stator coil configuration to reduce negative mutual inductance and resonant frequency before voltage surges can occur. This preventive approach eliminates the need for increased insulation thickness, maintaining compact phase-to-phase clearance while ensuring electrical insulation reliability
3Reliability
If the resonant frequency is reduced by modifying stator coil configuration, then the maximum phase-to-phase voltage decreases, but the manufacturing precision requirements increase
Solution Approach 1:
The patent changes the parameter of slot assignment for different winding sections, receiving the first section and kth section in different single-phase slots. This parameter change reduces negative mutual inductance and resonant frequency, achieving voltage reduction with standard manufacturing precision capabilities
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 configuration effectively reduces the maximum phase-to-phase voltage, minimizing the required phase-to-phase clearance for insulation and enhancing electrical insulation between phase windings, while also simplifying the manufacturing of the stator coil.
Implementation Method 1
sections of the phase windings received in different slots to minimize negative mutual inductance, reducing resonant frequency and resonance peak
Data Source
AI summary
An electric rotating machine includes a rotor and a stator. The rotor has a plurality of pairs of magnetic poles. The stator includes a stator core and a stator coil that is comprised of a plurality of phase windings wound on the stator core. The stator core has, for each of the phase windings of the stator coil, n circumferentially-consecutive single-phase slots, in which only the phase winding is received, per magnetic pole of the rotor, where n is a natural number not less than 2. Each of the phase windings of the stator coil has first to kth sections that are sequentially arranged from one end to the other end of the phase winding, where k is a natural number not less than 2. The first section is received in different ones of the single-phase slots for the phase winding from the kth section.