Power density and efficiency of system compatible, sine-wave input/output drives

Abstract

The benefits of Variable Frequency Drives (VFDs) have not been fully realized in many applications because they compete in the power density of legacy equipment, such as electro-mechanical motor controllers. This is especially the case in Navy shipboard systems where sensitive equipment is in close proximity to VFDs. In this context, this paper compares the power densities, efficiencies and costs of a Voltage Source Converter (VSC), Current Source Converter (CSC) and mixed VSC/CSC based VFDs. A meaningful comparison is made based upon an actual hardware implementation that meets stringent power quality and electromagnetic compatibility (EMC) requirements. Hardware results of a CSC/VSC based VFD are provided in order to support the findings of the study. Special consideration is given to operation at light loads.

Current source rectifiers in discontinuous conduction modes of operation

“…1, as opposed to the more common VSR or boost rectifier for both Variable Frequency Drive (VFD) and distributed DC bus applications [1]- [8]. Interest in this topology is due to the facts that system compatible interface to an AC service or mains can be accomplished with less and smaller external components [2], [7], [8] and that the topology is compatible with emerging power semiconductor devices such as the Silicon Carbide (SiC) MOSFET [5], [6]. Trends in literature demonstrate that the CSR is a more power dense alternative to the VSR for applications requiring low input current individual harmonic distortion (IHD) and low conducted electromagnetic interference (EMI) in power ranges of <20kW [7], [8].…”

“…Trends in literature demonstrate that the CSR is a more power dense alternative to the VSR for applications requiring low input current individual harmonic distortion (IHD) and low conducted electromagnetic interference (EMI) in power ranges of <20kW [7], [8]. Improved power density over the VSR is because the CSR does not impose differential mode voltage pulses on the input and common mode voltage is lower thus requiring less EMI mitigating hardware [7].…”

“…Interest in this topology is due to the facts that system compatible interface to an AC service or mains can be accomplished with less and smaller external components [2], [7], [8] and that the topology is compatible with emerging power semiconductor devices such as the Silicon Carbide (SiC) MOSFET [5], [6]. Trends in literature demonstrate that the CSR is a more power dense alternative to the VSR for applications requiring low input current individual harmonic distortion (IHD) and low conducted electromagnetic interference (EMI) in power ranges of <20kW [7], [8]. Improved power density over the VSR is because the CSR does not impose differential mode voltage pulses on the input and common mode voltage is lower thus requiring less EMI mitigating hardware [7].…”