Control method and device for constant-current frequency sweeping power supply of high-accuracy transformer

Abstract

The invention relates to a control method for a constant-current frequency sweeping power supply of a high-accuracy transformer. The control method comprises the steps of adjusting a carrier period in real time according to a current frequency instruction to obtain a reference frequency of an instruction current; controlling control on the instruction current to control on an output voltage, and generating a modulation wave by closed-loop control; sending the obtained modulation wave to a field programmable gate array / complex programmable logic device (FPGA / CPLD) pulse modulation circuit to be compared with a triangular carrier in real time so as to generate a switching pipe driving pulse; and judging whether the current reaches an instruction value or not so that a new frequency instruction is generated. The invention also discloses a control device for the constant-current frequency sweeping power supply of the high-accuracy transformer. The output frequency of a frequency converter can be continuous and adjustable, and the frequency accuracy is very high; the control on the output current is converted to the control on the output voltage, thus, the stability of the whole control system is improved; with the adoption of asynchronous modulation, the frequency of a driving pulse switch is fixed; and continuous judgment is performed on an effective value of the output current, and thus, the output current is enabled to reach the instruction value already.

Description

technical field [0001] The invention relates to the technical field of power electronics and magnetic element testing, in particular to a control method and device for a high-precision transformer constant-current frequency-sweeping power supply. Background technique [0002] The transformer is an important equipment in the power transmission and distribution link of the power grid. When using the mechanical vibration frequency response method to diagnose the fault of the transformer winding, a stable variable frequency constant current source is required. The design idea of ​​the variable frequency constant current source is to control the inverter after PWM modulation Output frequency and output voltage, and use negative feedback to make the load current track the given current to achieve constant current frequency sweep. Constant current sweeping power supply is mainly used for testing magnetic components such as transformers, so frequency conversion power supply is requi...

AI Technical Summary

Problems solved by technology

[0003] Traditional high-power inverters usually use IGBT as the switching device, the switching frequency is low, and the quality of the output waveform cannot be guaranteed in a wide frequency range, so the general frequency conversion range is narrow

For frequency converters with a wide frequency range, frequency hopping is usually used, but a large sine table needs to be established, and the frequency accuracy is not high, so continuous frequency changes cannot be achieved

In addition, the traditional constant current inverter power supply usually adopts current single closed-loop control, the system stability is poor, the dynamic response is slow, and oscillation is easy to occur

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