Individual DC Voltage Balance Control for Cascaded H-Bridge Electronic Power Transformer With Separated DC-Link Topology

Abstract

For the electronic power transformer, the dc voltage balance is an important issue. Unbalanced dc voltages will degrade the performance of the device and may trigger the dc voltage protection. In this paper, an overall individual dc voltage (including high-voltage and low-voltage dc-link voltages) balance strategy is proposed for the electronic power transformer with separated dc-link topology. The strategy adjusts active powers flowing through the isolation and output stages in different power modules to enhance the dc voltage balance capability. Through the strategy, the high-voltage and low-voltage dc-links can be well balanced when unbalance occurs among different power modules (e.g., component parameter mismatches or some of the high-voltage or/and low-voltage dc-links are connected with renewable energy sources or/and dc loads). The proposed strategy is analyzed and supported by experimental validation.

Soft‐switching modulation of the multilevel cascaded H‐bridge inverter under DC source fault

“…In fact, the batteries are usually charged by the rectifiers or the DC–DC converters. Figure 4(e) and (f) depicts two practical applications in the advanced co‐phase traction power supply system [14] and the power electronic transformer [12], respectively. So, the DC sources are generally based on the power electronic devices which are prone to unexpected failure owing to their complex structure and operation conditions, as well as their high electrical stress.…”

A Decentralized Optimal Operation of AC/DC Hybrid Microgrids Equipped With Power Electronic Transformer

“…where P i,ϕ loss.ac and P j loss.dc represent the power loss of the PET AC and DC port, respectively; ϕ = {a, b, c} is the three-phase system; k 0 , k 1 , k 2 are the fitting parameters of the loss, the current of PET AC and DC port are expressed by I i,ϕ ac and I j dc , respectively, and they are defined by (4) and (5), respectively. Actually, the loss model of isolation DC/DC transformer, including the DC/AC converter losses and high frequency transformer losses, also can be written as a function of the phase current magnitude [42], [43].…”

“…The power electronic transformer (PET) is also called solid state transformer (SST) or energy router [1], [2]. As the interface device between the distribution system and the electricity consumers in future smart grid, the PET with the capability to actively manage the power has received widespread attention [3]- [5]. The AC/DC hybrid microgrids equipped with PET provide a new method for the easy connection of the distribution resources in a large scale.…”

Research on Current Limiting Method Used for Short Circuit Fault Current of Resonant DC Transformer Based on Inverted Displacement Phase Control

“…Based on the above requirements, this paper has researched in depth on the current limiting control method of DC power electronic transformer using CLLC resonant converter circuit. On one hand, the design and optimization of the resonance parameters must meet the high-efficiency transmission requirements of the symmetrical CLLC resonant conversion circuit under ZVS and ZCS conditions, that is, the converter must meet the gain characteristics and soft switching realization conditions [16]- [18]. On the other hand, the low voltage ride-through requirement needs a precise control to the output current from transformer in case of short circuit happen.…”