Polyphase Machine Star Windings Negative Mutual Inductance
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Solution Overview
Problem
Polyphase electrical machines with multiple inverters experience disturbances and losses due to interfering currents when using interlaced control, which are not effectively mitigated by existing technologies without compromising galvanic insulation.
Innovation Solution
A polyphase electrical machine design featuring star windings with negative mutual inductance between homologous phase circuits, achieved through either external coupling transformers or appropriate coil winding configurations, to minimize interfering currents caused by interlaced control of inverters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple inverters are used with interlaced control to supply polyphase electrical machines, then the amperage of currents produced by each inverter is limited and redundancy is improved, but disturbing currents are generated causing heat losses and Joule effect losses
Solution Approach 1:
The patent introduces an intermediary coupling between the homologous phase windings of different star windings. This coupling acts as a mediator that allows the disturbing currents generated by interlaced inverter control to circulate through the coupled windings rather than causing losses in the motor. The coupling enables energy transfer between windings, converting what would be harmful circulating currents into useful electromagnetic energy.
Solution Approach 2:
The patent changes the electrical parameters of the motor by introducing coupled star windings with specific coupling coefficients. By adjusting the coupling parameter k (where 0 < k ≤ 1), the system optimizes the circulation of disturbing currents to minimize losses. The coupling transforms the nature of current circulation, changing it from a loss-generating phenomenon to a controlled energy transfer mechanism.
2Object-generated harmful factors
If inverters are connected galvanically to share common neutral points, then interfering currents between inverters are reduced, but galvanic insulation is compromised
Solution Approach 1:
The coupling between homologous phase windings serves as an intermediary that enables current sharing between inverters without requiring direct galvanic connection. The magnetic coupling through the coupled star windings allows the inverters to coordinate their current delivery while maintaining electrical isolation. This mediator approach eliminates the need for galvanic connections while still achieving the benefit of reduced interfering currents.
3Ease of operation
If disturbing currents circulate between inverter outputs, then interlaced control operation is maintained, but heat and losses are generated
Solution Approach 1:
The patent converts the harmful disturbing currents into a beneficial effect by providing coupled star windings that channel these currents into productive electromagnetic energy transfer. The disturbing currents that would normally cause heating and losses are instead utilized to transfer energy between the coupled windings, improving overall system efficiency while maintaining interlaced control operation.
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 design reduces heat losses and Joule effect losses by canceling out positive coupling between homologous phase windings, maintaining galvanic insulation and enhancing operational reliability with multiple inverters.
Implementation Method 1
the coupling between the homologous phase windings of the different star windings, and more particularly the positive coupling which is usually present between two homologous phase windings
Implementation Method 2
each phase circuit of a star winding has a negative mutual inductance with the homologous phase circuit of another star winding
Implementation Method 3
being controlled by an interlaced pulse-width-modulated control to an identical cutoff frequency between the inverters, providing, on their phase outputs, an alternating voltage signal having an identical fundamental frequency, amplitude and phase
Data Source
AI summary
The invention relates to a device having a polyphase electrical machine, wherein a plurality of inverters (36, 37, 38), which are controlled by an interlaced control modulated by pulse width to an identical cutoff frequency, provide, on the phase outputs thereof, an alternating voltage signal having an identical fundamental frequency, amplitude and phase to an electrical machine (2) that comprises at least two separate so-called star windings (33, 34, 35), each star winding being supplied by a related inverter, each phase output of which is connected to a phase circuit that includes the phase winding of the star winding, the device being characterized in that each phase circuit for a star winding has a negative mutual inductance with the homologous phase circuit of another star winding.