Switching power supply output short circuit and undervoltage protection circuit

Abstract

The invention discloses a short-circuit and low-voltage protective circuit of output of a switching power source. The short-circuit and low-voltage protective circuit of the output of the switching power source comprises a rectification filter unit, a switching voltage transformation unit, a primary control unit and a secondary feedback unit. The positive pole of the output end of the power source connected with a load is connected to a short-circuit and low-voltage protective unit through a backward diode, and when the load is shorted or the output is low in voltage, the short-circuit and low-voltage protective unit sends a feedback control signal to the primary control unit. According to the short-circuit and low-voltage protective circuit of the output of the switching power source, the short-circuit and low-voltage protective unit capable of generating the feedback control signal when the load is shorted is added besides an existing feedback loop, isolation is carried out through the backward diode, the sampling end of the short-circuit and low-voltage protective unit is connected at the connecting position of the output end of the power source and the load, the timeliness of short circuit detection is improved, the problem that the power source cannot be protected timely when the load is shorted or the output is low in voltage is solved, the needs of peak power of the load is guaranteed, the reliability of a switching power source converter is improved, and the service life of the switching power source converter is prolonged.

Description

technical field [0001] The invention relates to the technical field of switching power supplies, in particular to an output short-circuit and undervoltage protection circuit of a switching power supply, in particular to a high-reliability switching power supply short-circuit and undervoltage protection circuit applied to motor drives. Background technique [0002] Nowadays, with the wide application of medium and small DC motors in various fields, the control technology of DC motors is also more sophisticated and complex. The energy supply of DC motors comes from AC-DC switching power supplies. Due to the inherent starting characteristics of motors, the existing traditional solutions The current AC-DC switching power supply can no longer meet the functional requirements. The existing motor has a large peak current at the moment of starting. In the design protection function of AC-DC switching power supply, it must have basic short circuit protection and overvoltage protectio...

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Problems solved by technology

[0002] Nowadays, with the wide application of medium and small DC motors in various fields, the control technology of DC motors is also more sophisticated and complex. The energy supply of DC motors comes from AC-DC switching power supplies. Due to the inherent starting characteristics of motors, the existing traditional solutions The AC-DC switching power supply can no longer meet the functional requirements

The existing motor has a large peak current at the moment of starting. In the design protection function of AC-DC switching power supply, it must have basic short circuit protection and overvoltage protection. Then the design of switching power supply can ensure the maximum load rated power and take into account all aspects. Protection function and cost control, then the peak power setting is too small, so that the short circuit protection of the power supply is easy to design, but the motor will not start; The consistency is not easy to control, and the whole switching power supply will be burned when the load simulation test is short-circuited. At the same time, there are many special load instruments and equipment that will cause great damage to long-term undervoltage operation, so there are major safety hazards and reduce the service life of the product. , which greatly reduces the reliability of the AC-DC switching power converter

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