Mixed linear amplified megawatt resonant power supply used in partial discharge measurement

Abstract

The invention discloses a mixed linear amplified megawatt resonant power supply used in partial discharge measurement, which comprises a full-bridge output stage; the full-bridge output stage uses a N-type electric field to control power devices, and consists of two same half-bridge output stages, namely, an A half-bridge output stage and a B half-bridge output stage, and each half-bridge output stage is composed of a compensated amplifier, a main amplifier, an overcurrent protection circuit and a negative feedback circuit, wherein the compensated amplifier is formed in a way that a precedingstage is connected to a compensating stage (having bias currents) of the power device by way of direct-current coupling; the main amplifier is formed in a way that a same preceding stage is connectedto a driver stage by way of direct-current coupling, and then connected to a final power stage (having no bias current) of the power device by an overcurrent control gate by way of direct-current coupling; and the overcurrent protection circuit and the negative feedback circuit can protect each device. In the invention, double overcurrent protection can be carried out on each power tube; and the final power stage of a main amplification stage has zero bias, namely, has no static bias current. Therefore, not only the loss is reduced and the efficiency is improved, but also the temperature stability is increased; because a strong direct-current coupling negative feedback is added, the defect of weak linearity of the power devices is overcome, the index of distortion factor is improved, and the output impedance of the resonant power supply is reduced.

Description

technical field [0001] The invention relates to the technical field of power systems, in particular to a hybrid linear amplified megawatt-level resonant power supply used in partial discharge measurement. Background technique [0002] Transformers, transformers, cables, etc. in the power system need to be tested for withstand voltage and partial discharge. In order to generate AC ultra-high voltage for testing above 500KV, a series resonant device is generally used to increase the output voltage to Q times the input voltage. Q is the quality factor of the series resonant device, ranging from tens to hundreds. Therefore, compared with the direct step-up of the transformer, the volume and weight of the equipment can be greatly reduced, which is convenient for on-site testing. [0003] In order to make the LC circuit resonate, it is most convenient to change the frequency of the power supply, and the resonance effect is the best. However, a high-power sine wave power supply ...

AI Technical Summary

Problems solved by technology

Take the resonant power supply with an output power of 450KW produced by a domestic company using this technology as an example. Nearly 100 transistors are installed in each plug-in, and more than 80 plug-ins are used in total, which makes the cabinet structure of the whole machine equipment very complicated and costly.

[0019] 2. Both drive and negative feedback adopt relatively high-power transformers, and their phase shift is relatively large, so it is difficult to add negative feedback with a depth of more than 20db

The load is the primary of the intermediate transformer wound with flat copper strips, and the DC resistance is very small, so even if there is a small difference in the DC levels output by the two half-bridges, a large DC circulation will be formed, which will increase the loss and reduce the reliability.

[0022] 5. The frequency range of the whole machine is not high, generally below 1KHz

Although only 30-400Hz is used in general tests, the inability to output higher frequencies limits the performance of the device

[0023] The above technical problems were discovered by the manufacturer during the adjustment of the machine and the users in the power department, and cannot be completely solved.

Due to the low reliability of the mainframe, it has greatly hindered the promotion of this technology

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