56results about How to "Eliminate inrush current" patented technology

The invention discloses a flux linkage control-based transformer and an excitation surge suppression method. A small-capacity DC / AC converter is connected to a secondary winding or an auxiliary winding of the transformer, a voltage phase of a power grid at a primary side is detected before no-load closing, and a reference instruction of iron core flux linkage is derived according to a relation between a winding voltage and the iron core flux linkage. An iron core flux linkage closed-loop PI control system is built under a synchronous rotating reference system, so that an output voltage of theconverter is controlled, zero-error tracking of the iron core flux linkage on a flux linkage reference value is performed, and sine synchronous flux linkage having phase difference with the power gridvoltage being 90 degrees can be built in advance in an iron core before no-load closing. By the measure, the iron core flux linkage is directly in a steady state without transient process no matter when the transformer is closed, so that the excitation surge can be thoroughly eliminated.

The invention belongs to the technical field of switching power supply soft start, and provides an adaptive soft start circuit applied to a boost topology switching power supply, which is used to overcome the problem of too long invalid start time of the existing soft start circuit; including a clock module and a zero-crossing detection module , counter module and digital-to-analog conversion module, the clock module generates two clock signals, fast and slow, to input the counter module; the zero-crossing detection module generates a control signal to the counter module according to the size of the energy storage inductor current; the counter module selects the fast clock signal according to the control signal The clock signal or slow clock signal is used as the counting clock to realize counting at different speeds and output binary counting values; the digital-to-analog conversion module converts the binary counting values ​​output by the counter into analog signals, and outputs soft-start reference voltages that rise in steps. The present invention introduces a zero-crossing detection control signal, self-adaptively adjusts the rising rate of the soft-start reference voltage, and greatly shortens the invalid soft-start time of the boost topology switching power supply.

The invention relates to the technical field of grid-connected inverters, in particular to a method for starting a grid-connected inverter, which compares the effective value of the inverter phase voltage with a preset first reference voltage value to judge the grid-connected inverter Whether the relay is bonded, in a mains cycle, the relay is controlled by comparing the difference between the collected current inverter phase voltage value and the instantaneous value of the mains phase voltage with the preset third reference voltage value Turn off, to realize the accurate detection of the effectiveness of the inverter switch tube and the grid-connected relay before the inverter is connected to the grid, and at the same time eliminate the inrush current when the relay is closed and the inrush current caused by the switching tube driving wave when the grid is connected, and finally make the Photovoltaic grid-connected inverters can be successfully connected to the grid and have long-term stable grid-connected power generation.