DC-Link Busbar Network Design and Evaluation Method for the Large-Capacity Power Electronic Converter

Abstract

For the dc-link busbar in a high-capacity converter, the large-size laminated busbar is not adoptable due to the machining difficulty and limitation in current capability. In contrast, the regular nonlaminated busbar solution guarantees the required power capacity with a lower cost and easier installation. The main challenges exist in the large stray inductance and corresponding resonance phenomenon. Related analysis and accurate synthesis theory have not been reported. In this article, a matrix analysis method is proposed for the formed multiport and high-order network in a dc-link busbar. First, the multiport interaction and coupling are mathematically derived based on the subnetwork admittance matrix combination. The multipeak resonance phenomena are explained in detail. Meanwhile, it is manifested that proposed matrix method can be applied with the positive and negative sequence current analysis. Then accurate resonate currents can be obtained under the nonsinusoidal busbar current consideration. Finally, a resonance current gain (RCG) value is formed for the quantitative capacitor current evaluation and busbar design guidance. Proposed design and evaluation method is verified in a 315-kW converter system. More than 49% resonant current in the capacitor gets depressed by the enhancement. Its effect is close to the laminated busbar solution.