According to the phase relationship of the electromotive force of the primary and secondary edge of the transformer, the different connections and labels of the transformer winding are divided into different combinations, which are called connection groups, which reflect the phase relationship of the primary and secondary electromotive forces of the transformer.
Flux coupling transformer is a kind of static electrical appliance, which converts one voltage level of alternating current energy into another voltage level of frequency through electromagnetic induction between coils, to be precise, it has the functions of voltage transformation, current transformation, conversion impedance and isolation circuit. For example, in the power system, flux coupling transformers are used to increase the voltage emitted by generators for long-distance transmission, and then use transformers to reduce the voltage for users after reaching the destination.
Flux coupling transformer is used in laboratory to change the power supply voltage, in the measurement of the instrument transformer to expand the measurement range of AC voltage and current, in electronic equipment and instruments with low-power power transformer to provide a variety of voltages, flux coupling transformer to transmit signals and isolate the connection on the circuit, etc. At present, as long as the photovoltaic power station is properly designed and can be operated economically, the transformerless inverter directly integrated into the grid is increasingly valued because of its low cost and high efficiency. However, the technology is still considered "problematic". This will be examined and illustrated below.
The flux coupling transformer adopts the wire drawn by the oxygen-free copper rod with higher conductivity than the electrolytic copper, improves the conductivity coefficient, appropriately reduces the current density, improves the insulation structure, adopts semi-oil duct, prefabricated insulators, complete transposition of windings, winding sleeve sets, self-adhesive wires, and self-adhesive paper to reduce the insulation volume, improve the winding filling coefficient, reduce the winding size, and adopt optimized design. The flux coupling transformer improves the core structure, controls the leakage magnetic flux of the windings in the design, adjusts the ampere turn balance to reduce the stray loss of the fuel tank and other structural parts, replaces the tubular radiator with corrugated fuel tank, sheet radiator and heat pipe, and replaces the old-fashioned radiator with a new structure for heat dissipation to improve the heat dissipation efficiency.
The flux coupling transformer adopts a reinforced plastic fan to improve efficiency and reduce noise, the magnetic screen or electrical shielding reduces the stray loss of the fuel tank, the use of non-magnetic materials as bundles or magnetic flux separators to reduce stray loss, and the use of the working characteristics of the working machinery to reduce the loss. If the voltage is adjusted with the change of load, so that the working machinery is always kept near the highest efficiency, try to maintain the three-phase current balance, and eliminate or reduce harmonics, the energy consumption can be reduced.
