Fast testing platform for the isolation transformer

This work shows a program created in a Labview environment to verify the correct functioning and regulatory compliance of isolation transformers and isolation transformers for medical use. The transformer tests will be divided into acceptance tests and type tests. For each type of test, the program will be able to provide information for correct testing and to speed up the test path.The guided test procedure will accompany the author up to the automatic printing of the test reports. Finally, considerations will be made on which tests to perform on already installed transformers that require recertification.

A special high-frequency soft-switched DC/DC power supply for GCT gate driver

This thesis is devoted to the development of a novel parallel isolated power supply (PIPS) for the gate driver of integrated Gate Commutated Thyristors (GCT). The proposed PIPS is essentially a special high frequency soft switched DC/DC converter, integrating six parallel isolated power supplies in one module where each power supply generates a regulated dc supply for the GCT gate driver. In commercial GCT power supplies, a high-voltage isolation transformer is indispensable but highly inefficient in terms of cost and size, which can be significantly improved by the optimized transformer. In all, this design strives to achieve a general power supply for powering up the gate drivers of all types of GCT devices in all MV applications with minimal changes in configuration. In this thesis, the configuration of PIPS is presented and its operating principle is elaborated. The transformer optimization procedure satisfying the voltage isolation requirement of GCT gate drivers is extensively discussed. The performance of PIPS, including the front end DC/DC converter, zero voltage switching phase-shift full bridge (ZVS-PS-FB) converter, and the optimization of the transformer, is verified by simulations and experiments where a 360W laboratory prototype is built for the experimental use.

A special high-frequency soft-switched DC/DC power supply for GCT gate driver

This thesis is devoted to the development of a novel parallel isolated power supply (PIPS) for the gate driver of integrated Gate Commutated Thyristors (GCT). The proposed PIPS is essentially a special high frequency soft switched DC/DC converter, integrating six parallel isolated power supplies in one module where each power supply generates a regulated dc supply for the GCT gate driver. In commercial GCT power supplies, a high-voltage isolation transformer is indispensable but highly inefficient in terms of cost and size, which can be significantly improved by the optimized transformer. In all, this design strives to achieve a general power supply for powering up the gate drivers of all types of GCT devices in all MV applications with minimal changes in configuration. In this thesis, the configuration of PIPS is presented and its operating principle is elaborated. The transformer optimization procedure satisfying the voltage isolation requirement of GCT gate drivers is extensively discussed. The performance of PIPS, including the front end DC/DC converter, zero voltage switching phase-shift full bridge (ZVS-PS-FB) converter, and the optimization of the transformer, is verified by simulations and experiments where a 360W laboratory prototype is built for the experimental use.

A novel self-powered supply for GCT gate drivers

This thesis is devoted to the development of a novel self-powered supply (SPS) for the gate driver of integrated Gate Commutated Thyristors (GCT). In commercial GCT power supplies, a high-voltage isolation transformer is an indispensable device. Since the GCT devices are normally for high-power converters operating at a voltage level of 2.3KV to 13.8KV, the high-voltage isolation transformer is expensive in cost and bulky in size. The SPS proposed in this thesis transfers energy from GCT snubber circuits and generates a regulated dc supply for the GCT gate driver. Since the snubber circuit is at the same potential as the GCT device, the insulation level of the self-powered supply is reduced from a few thousand volts to a couple of hundred volts, leading to a significant reduction in cost and size. In this thesis, the configuration of the proposed SPS is presented, and its operating principle is elaborated. The strategy for maximizing the SPS output power is analyzed. It is demonstrated that SPS can provide a regulated output up to 60W for most commercial GCT gate drivers. The performance of the SPS is verified by experiments on a 60W laboratory prototype.

A novel self-powered supply for GCT gate drivers

This thesis is devoted to the development of a novel self-powered supply (SPS) for the gate driver of integrated Gate Commutated Thyristors (GCT). In commercial GCT power supplies, a high-voltage isolation transformer is an indispensable device. Since the GCT devices are normally for high-power converters operating at a voltage level of 2.3KV to 13.8KV, the high-voltage isolation transformer is expensive in cost and bulky in size. The SPS proposed in this thesis transfers energy from GCT snubber circuits and generates a regulated dc supply for the GCT gate driver. Since the snubber circuit is at the same potential as the GCT device, the insulation level of the self-powered supply is reduced from a few thousand volts to a couple of hundred volts, leading to a significant reduction in cost and size. In this thesis, the configuration of the proposed SPS is presented, and its operating principle is elaborated. The strategy for maximizing the SPS output power is analyzed. It is demonstrated that SPS can provide a regulated output up to 60W for most commercial GCT gate drivers. The performance of the SPS is verified by experiments on a 60W laboratory prototype.

Novel Five-Level ANPC Bidirectional Converter for Power Quality Enhancement during G2V/V2G Operation of Cascaded EV Charger

This paper presents a novel single-phase (SP) active-neutral point clamped (ANPC) five-level bidirectional converter (FLBC) for enhancing the power quality (PQ) during the grid-to-vehicle (G2V) and vehicle-to-grid (V2G) operation of an electric vehicle (EV) charger connected in series. This EV charger is based on a dual-active half-bridge DC-DC converter (DAHBC) with a high frequency isolation transformer. Unlike the comparable ANPC topologies found in literature, the proposed one has two more switches, i.e., ten instead of eight. However, with the addition of these components, the proposed multilevel converter not only becomes capable of properly balancing the voltage of the DC-link split capacitors under various step-changing conditions but it achieves a better efficiency, a lower stress of the switching devices and a more even distribution of the power losses. The resulting grid-tied ANPC-SPFLBC and DAHBC are accurately controlled with a cascaded control strategy and a single-phase shift (SPS) control technique, respectively. The simulation results obtained with MATLAB-SimPowerSystems as well as the experimental results obtained in laboratory validate the proposed ANPC-SPFLBC for a set of exhaustive tests in both V2G and G2V modes. A detailed power quality analysis carried out with a Fluke 43B alike demonstrates the good performance of the proposed topology.

Design and Implementation of 2.5kW IBFB-LLC DC/ DC Converter Using SiC Mosfet

Interleaved Boost Full Bridge integrated LLC resonant (IBFB- LLC) is an isolated DC/DC converter with directional power flow, which can cope with a wide input voltage range of PV applications. The main losses of the converter are switching losses of the power switches and transformers losses. This paper proposes a method to improve the efficiency of the IBFB converter due to zero voltage switching technique, in combination with employing new SiC MOSFET technology instead of the conventional Si MOSFET. In addition, Litz wire is also adopted to reduce the losses on the high frequency isolation transformer. Both numerical simulations and experiments with a prototype 2.5kW converter are implemented to verify the feasibility and effectiveness of the proposed solution.