However, as smaller gage cables and associated components are more readily available, the overall impact of multi-phase systems yields a small reduction in price as shown in the following table ( prices are for low volumes): Typically the more parts you use in your integration, the higher the costs. Smaller and lighter cables also benefit from easier handling and preparation by requiring less cumbersome tools and smaller support brackets Although suffering from a slightly higher cable loss, the larger cooling area of the multi-phase cables provides for a cooler cable temperature.Īs shown in the previous table, the bending radius of the smaller gage cable is reduced by 50% this allows for a tighter and cleaner integration around other vehicle peripherals and brackets. This yields an overall reduction of copper surface of 38% and weight of 33%.
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Next is a table comparing a single three-phase system with a SUMO™HD 9-phase system (3 x three-phase) at equivalent output current.
Bay motor winding skin#
Typical electrical systems have maximum fundamental frequencies up to 1 to 1.5 kHz which are sufficient to produce significant skin effect in large cables this can become significant even at low frequency as presented next for a system at about 10% max speed. The larger the cable and higher the frequency, the more pronounced this effect becomes. As current frequency increases, current tends to flow at the outer edge of the wires while avoiding the center area. More efficient use of cable cross-sectional areaĪt first view, 3 cables with a larger cross-sectional area may seem to be able to carry more current than 6 or 9 several smaller gage cables, but at TM4, we have proven that this is not the case. The end result is that for a defined DC bus voltage ripple requirement, the DC filtering capacitor can be significantly reduced thereby reducing costs as well as product size and weight.ģ. The following figures show the values of the DC filtering capacitor current for one, two or three -phase systems using the same capacitor and output current. This spreads the current ripple demand from the DC bus filtering capacitor among the IGBTs allowing to use a smaller capacitor whilst retaining the equivalent DC bus voltage ripple. As the IGBTs are fully independent of each other in our systems, we are able to benefit from interleaved IGBT switching. The industry is always looking for ways to reduce component costs and our multi-phase topology allows to do just that. Reduced component costs and DC bus ripple
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TM4’s multi-phase modular topology of inverters and motors uses independent IGBTs to drive independent electromagnetic subsets of the motor thereby allowing each IGBT to be used to its fullest potential. The immediate problem is that IGBTs are never perfectly matched and current does not distribute evenly between parallelized IGBTs this can cause a loss in performance of more than 10% compared to the performance we could expect from the sum of the same number of independent IGBTs. The most common approach to increasing power is the parallelisation of multiple power transistors (IGBT). TM4 offers a scaled line of multi-phase inverters and electric motors combinations: One question our sales representatives often get is related to Dana TM4’s multi-phase approach what advantages do 6- and 9-phase electric powertrains provide in comparison with more traditional three-phase systems? Let’s take a look at the top 5 benefits multi-phase systems can offer.