Switch power circuit for frequency converter

Abstract

The utility model relates to a switching power supply circuit of the frequency converter, comprising a power conversion circuit, a first PWM control circuit, a main transformer, an isolated feedback circuit, a sampling comparator, a reference voltage circuit, a first rectification circuit, a first filter circuit and a first output; the utility model also comprises at least more than one subordination transformer, a MOS transistor, a second PWM control circuit; wherein an output of the main transformer is connected directly with one or a plurality of inputs of the subordination transformer; the other end of the main transformer is connected with the source electrode of the MOS transistor; meanwhile the drain electrode of the MOS transistor is connected with one or a plurality of other ends of the subordination transformer; the output of the second PWM control circuit is connected with the grid electrode of the MOS transistor; after the output of the subordination transformer passes the second rectifier circuit and the second filter circuit, the second output becomes the input power supply of IGBT. The utility model has the advantages that the design of the main transformer and the subordination transformer is better and the precision is improved.

Description

technical field [0001] The invention relates to a frequency converter, in particular to a switching power supply circuit of the frequency converter. Background technique [0002] The frequency converter is a device that adjusts the speed of the motor by adjusting the frequency of the grid. Frequency conversion speed regulation has the advantages of wide speed regulation range, high speed regulation precision, fast dynamic response, good low-speed torque, energy saving, high work efficiency, and convenient use. The application of frequency conversion speed regulation can not only make the motor run at an energy-saving speed, but also greatly improve the control accuracy of the motor speed, improve the process quality and production efficiency. [0003] It can be seen from Figure 1 and Figure 2 that the switching power supply circuit diagram of a low-power inverter is composed of a power conversion circuit 6, a PWM control circuit 7, a main transformer 1, an isolated feedback...

AI Technical Summary

Problems solved by technology

Figure 2 is a power supply circuit of a low-power inverter, and the number of skeleton pins used is 30; if it is applied to a high-power inverter, the number of pins used is at least 46, and it is difficult to use a skeleton with so many pins. turn up

Secondly, the winding of the transformer is inconvenient. Due to the existence of leakage inductance, the output voltage of the inner layer coil will be smaller than that of the outer layer when the number of turns of the coil is the same. Since the voltage difference between the IGBT driving voltages is large, it cannot be used They are wound on the same layer, so the output voltage of the wound transformer is quite different from the designed voltage, and the accuracy is difficult to control

The consequences will even burn out the IGBT

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