Same-phase power supply system based on single-phase full-bridge diode clamping multilevel back-to-back converter

Abstract

The invention discloses a same-phase power supply system based on a single-phase full-bridge diode clamping multilevel back-to-back converter. A secondary winding of an alpha-phase step-down transformer (2) is parallelly connected with an input end of a diode clamping multilevel rectifier through a connecting reactor (5), an output end of the diode clamping multilevel rectifier is parallelly connected with a second winding of a beta-phase step-down transformer (3) through a connecting reactor (5), and parallel output is connected in a traction network to power a load; a signal controller (7) mainly collects load current I load, phase signals of alpha-phase voltage and beta-phase voltage and voltage Vdc of a direct-current side capacitor, and current I alpha and I beta is controlled to be equal through a control circuit, so that balance of three-phase current on a network side is guaranteed. When the same-phase power supply system is applied in high-voltage high-power places, switch stress borne by devices can be lowered, switch loss of the devices is reduced, du / dt, di / dt and output waveform harmonic content during circuit running are lowered, capacity, grade and efficiency of the circuit are improved, and functions of the circuit are enabled to be more advantageous; the whole system is enabled to be small in loss and long in service life, so that maintenance frequency is lowered greatly.

Description

technical field [0001] The invention relates to an in-phase power supply system based on a single-phase full-bridge diode clamp multilevel back-to-back converter. Background technique [0002] The traction load of the electrified railway is a single-phase AC load, which makes the three-phase of the traction power supply system seriously unbalanced and has reactive current. In order to reduce the impact of three-phase unbalance, the balance transformer is connected by commutation, which leads to different voltages in each power supply section, so it must be separated by a phase-splitting insulator. The phase-splitting insulator restricts the smooth and continuous current receiving of the locomotive, and becomes a weak link of power supply, restricting the development of high-speed and heavy-haul railways. The same-phase power supply technology fundamentally solves the problem of electrical phase separation. Through real-time detection of the comprehensive compensation curren...

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Problems solved by technology

Both of these methods use bulky, expensive, and energy-consuming transformers. The latter will have many problems such as excessive current in the intermediate link, reduced efficiency, reduced reliability, and difficult energy transmission.

Moreover, in order to obtain a high-quality output waveform, the two-level circuit increases the switching frequency, which will cause a large loss in the switch, and there will be a large du / dt and surge voltage

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