SK2262017U1 - Liquid cooled isolation MF transformer of toroidal shape - Google Patents

Abstract

A fluid-cooled mid-frequency power separator transformer with vtoroid design, characterized in that a liquid condenser (20) is inserted between the magnetic circuit (10) and the primary coil (30) to drain losses from the magnetic circuit (10), while maintaining the high voltage requirements. strength for use as a separator transformer (50). The proposed solution makes it possible to realize galvanic separated DC-DC converters of switched power sources. The coolant in this case is not a transformer oil, but water, respectively. a mixture of antifreeze with water for use at ambient temperature even at a temperature below freezing.

Description

The technical solution relates to a design for a medium-frequency power transformer in toroidal design with adaptation for cooling the magnetic circuit and partly also winding with liquid while maintaining the requirement for high voltage strength and low level of partial discharges. The coolant in this case is not transformer oil, but water or water. a mixture of antifreeze with water for use at ambient temperature and below freezing.

BACKGROUND OF THE INVENTION

Isolating transformers are an immediate part of galvanically isolated DC-DC converters of higher voltage and power. The proposed solution enables to realize galvanically isolated DC-DC converters of switched power supplies with higher output (more than 40 kVA) using liquid-cooled isolation mid-frequency power transformer. Active interest in switched power supplies is directly related to electromagnetic compatibility (EMC) and performance characteristics that force the search for new inverter configurations. Attention is paid to increasing the specific power of the inverter by using appropriate technologies and active and passive elements with low losses. Switching power supplies themselves are characterized by different wiring diagrams depending on output power, supply voltage and its tolerance, output voltage and its stability, overall efficiency and so on. Due to the required dimensions and weight of the transducers, these are switched at higher frequencies, and the isolation transformer in question must also operate at a higher frequency than the mid-frequency power transformer.

For most medium power converters, switching frequencies are from 10 to 30 kHz, and in the next decade, due to the development of new semiconductor devices, this will shift to a frequency of 50 kHz with a perspective of up to 100 kHz. For these switching frequencies, the magnetic circuit material, the winding and its insulation system must be designed. From the available materials, the medium frequency power transformers in question can be realized using magnetically soft materials of amorphous metal materials (AKM), nanocrystalline materials (NKM), or ferrites. In view of the increasing demand for increasing specific power, the use of ferrite cores for this mid-frequency transformer power class is outdated due to the dimensions and weight of such mid-frequency transformer. Depending on what is commercially available on the market, toroidal or split (cut, 2C-shaped and glued to the side edges) cores from both (AKM) and NKM can be used depending on the core shape. To a much wider extent, toroidal cores of AKM and ACM are available. However, their use is technologically feasible for medium-frequency transformers with a maximum output of about 40 50 kVA (depending on the frequency and voltage value, respectively transformer transfer, insulation strength etc.), due to the feasibility of windings in the application of forced air cooling. Requirements for further increasing the power of switched power supplies and hence the parameters of magnetic circuits, reflected in the increasing power of the transformers in question, generate new requirements, of which the need for power increase, dimension and weight optimization, which is difficult to implement with toroidal core shapes, natural cooling or forced blowing, and therefore it is necessary to design a magnetic circuit with a different core shape than toroidal shapes, or to design a more efficient cooling method.

The essence of the technical solution

The desired power increase while maintaining the toroidal design can be achieved by implementing liquid cooling with an emphasis on the removal of heat from the core (s) of the mid-frequency power transformer. The principle of the technical solution consists in that between the toroidal core (s) and the winding of the primary coil is inserted a designed liquid cooler made of a copper pipe blank. Depending on the power of the transformer, the number of individual cores of the magnetic circuit and thus the size of the designed liquid cooler of the toroidal transformer cores also depend. There is an insulating gap between the core (s) and the liquid cooler, likewise the liquid cooler and the winding, depending on the desired stress strength. Requirement for increased insulation strength and min. The level of partial discharges, designed as a separating transformer, is ensured by placing the individual components in the housing and embedding it with polyurethane (or epoxy) resin. The dimensioning of the cores, but also of the primary winding is influenced by the heat dissipation achieved by means of the designed liquid cooler, the flow of coolant through the cooler but also by its temperature.

SK226-2017 U1

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1: Method of making a liquid cooler FIG. 2: A view of the principle representation of the design of a liquid (water) cooled medium-frequency isolation transformer of a toroidal design

EXAMPLES

In FIG. 1 and 2 show a specific example of realizing a technical solution for realizing a mid-frequency power transformer with liquid air cooling. The transformer consists of several main parts: a magnetic circuit h0, a liquid cooler 20, a primary coil 30, a secondary coil (s) 40 and a transformer housing 50.

The magnetic circuit 10 comprises a pair (or triple, 4, 5 ... n) of toroidal cores of nanocrystalline material, the cores are wrapped with insulation 11, a liquid cooler 20, with connectors 21 and 22 for the inlet, is placed outside the magnetic circuit 10. the coolant outlet 20 is also encased in insulation 61. Another layer 30 is a primary coil (or multiple coils) formed by a high-frequency harness winding with an input terminal 31 and an output terminal 32. This is followed by a secondary coil (or multiple coils) formed by a coil a high-frequency wire conductor with an input terminal 41 and an output terminal 42. Magnetically non-conductive spacers 62 are interposed between the individual layers so as to maintain the desired position and spacing of the individual layers 10 to 50. The transformer thus constructed is vacuum sealed with an insulating material. epoxy nutrients ca).

Industrial usability

The design of a liquid-cooled mid-frequency power isolation transformer can be used to build higher-power DC-DC converters to assemble locomotives, locomotives, stabilized power sources for powering magnetic synchrotron systems, continuous power supply systems and renewable power generation. Significant savings in dimensions and weight of the transformers themselves, compared to solutions with transformers realized at the average frequency.

Claims (1)

A toroidal liquid-cooled mid-frequency power isolation transformer, characterized in that between the magnetic circuit (10) and the primary coil (30) is a kva5 palm cooler (20) for dissipating losses. a magnetic circuit (10).