Non-isolated power supply structure with low-voltage starting function

Abstract

The utility model discloses a non-isolated power supply structure with a low-voltage starting function. The non-isolated power supply structure comprises a commercial power input circuit, a rectifier bridge circuit, an MOS tube control circuit connected with the rectifier bridge circuit, a power supply chip connected with the MOS tube control circuit, and a constant transformer circuit connected with the MOS tube control circuit. The control end of the power supply chip is connected with the constant transformer circuit; a rectification filtering current limiting circuit is arranged between the starting voltage end of the power supply chip and the commercial power input circuit, and the control end of the MOS tube control circuit is connected with the PWM driving end of the power supply chip. According to the utility model, the structure arrangement is reasonable, the rectification filtering current-limiting circuit is arranged between the starting voltage end of the power supply chip and the commercial power input circuit, and when the commercial power voltage is reduced, the voltage entering the power supply chip is stable, so that the voltage entering the power supply chip is not influenced by high-voltage direct-current fluctuation, and the condition of flashing is avoided; and the use stability and reliability can be improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of non-isolated power supplies, and in particular relates to a non-isolated power supply structure with a low-voltage starting function. Background Art

[0002] A non-isolated power supply is a common power supply structure, which means that there is a direct current loop between the input and the output, for example, the input and the load are in common ground. The non-isolated circuit has the advantages of simple structure, small size, low cost and high efficiency. The efficiency of a general non-isolated power supply can reach more than 92%, while the isolated power supply can generally only reach about 85%. In addition, when carrying a high-power load, the non-isolated power supply generates less heat. For example, the Chinese patent publication number is: CN210431239U, and the patent name is: A non-isolated power supply, including an output rectifier circuit, an inverter circuit and an isolation transformer; the power input end is connected to the primary winding of the isolation transformer through the inverter circuit, the secondary winding of the isolation transformer is connected to the input end of the output rectifier circuit, and the output end of the output rectifier circuit is connected to the output end of the power supply; the inverter circuit is connected to the secondary winding of the isolation transformer or the output end of the output rectifier circuit through hard-line sampling.

[0003] Although it can meet the general usage requirements, in actual application, its power chip is directly started and powered by high-voltage DC. When the mains voltage is reduced, the high-voltage DC fluctuates greatly, which can easily cause flashing lights, affecting the stability of use and service life, and limiting its applicability and practicality. Utility Model Content

[0004] The utility model aims to provide a non-isolated power supply structure with a low-voltage starting function, which has a reasonable structural arrangement and is conducive to improving the stability of use.

[0005] The technical solution for achieving the purpose of the utility model is a non-isolated power supply structure with a low-voltage starting function, comprising a mains input circuit, a rectifier bridge circuit connected to the mains input circuit, a MOS tube control circuit connected to the rectifier bridge circuit, a power chip connected to the MOS tube control circuit, and a constant transformer circuit connected to the MOS tube control circuit;

[0006] The control end of the power chip is connected to the constant transformer circuit;

[0007] A rectifier, filter and current limiting circuit is provided between the starting voltage terminal of the power chip and the mains input circuit, and the control terminal of the MOS tube control circuit is connected to the PWM driving terminal of the power chip.

[0008] It is further preferred that: the rectification, filtering and current limiting circuit comprises a seventh unidirectional diode, a sixth resistor and a fourth capacitor;

[0009] The anode of the seventh unidirectional diode is connected to the mains input circuit, the sixth resistor is connected in series to the cathode of the seventh unidirectional diode, and the other end of the sixth resistor is connected to the starting voltage terminal of the power chip;

[0010] One end of the fourth capacitor is connected to the cathode of the seventh unidirectional diode and the other end is grounded.

[0011] Further preferably, the MOS tube in the MOS tube control circuit is an N-MOS tube.

[0012] The utility model has positive effects: the structure of the utility model is reasonably set up, and a rectifier, filter and current limiting circuit is arranged between the starting voltage end of the power supply chip and the AC input circuit. When the AC voltage is reduced, the voltage entering the power supply chip is stable, so that the voltage entering the power supply chip is not affected by the high-voltage DC fluctuation, and there will be no flashing light, which is beneficial to improving the stability and reliability of use, and has strong applicability and good practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to make the content of the utility model easier to understand, the utility model is further described in detail below according to specific embodiments and in conjunction with the accompanying drawings, wherein:

[0014] Figure 1 It is a schematic diagram of a specific circuit structure of the utility model.

[0015] Figure numerals: mains input circuit 1, rectifier bridge circuit 2, MOS tube control circuit 3, power chip 4, constant transformer circuit 5, rectifier filter current limiting circuit 6. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0017] Example

[0018] See Figure 1As shown, a non-isolated power supply structure with a low-voltage starting function includes a mains input circuit 1, a rectifier bridge circuit 2 connected to the mains input circuit, a MOS tube control circuit 3 connected to the rectifier bridge circuit, a power chip 4 connected to the MOS tube control circuit 3, and a constant transformer circuit 5 connected to the MOS tube control circuit; the control end of the power chip is connected to the constant transformer circuit; in this embodiment, the above circuits are all conventional circuits of the prior art, so they are not described in detail, and the power chip can adopt LNK3204D, UCC28881, OB2333 and other chips, and the MOS tube in the MOS tube control circuit is an N-MOS tube.

[0019] In this embodiment, a rectifier filter current limiting circuit 6 is provided between the starting voltage terminal of the power chip and the mains input circuit, and the control terminal of the MOS tube control circuit is connected to the PWM drive terminal of the power chip. After the power chip is started, the PWM waveform is output to drive the MOS tube in the MOS tube control circuit to adjust the duty cycle and frequency to output a constant voltage. The mains is rectified into a high-voltage direct current through a rectifier bridge circuit (D1-D4), and then the high-voltage direct current is stepped down to a constant voltage through a MOS tube circuit and a constant transformer circuit.

[0020] In this embodiment, the rectifier, filter and current limiting circuit 6 includes a seventh unidirectional diode D7, a sixth resistor R6 and a fourth capacitor C4; and, the positive electrode of the seventh unidirectional diode is connected to the AC input circuit, specifically, to the N input terminal of the AC input circuit, the sixth resistor is connected in series to the negative electrode of the seventh unidirectional diode, and the other end of the sixth resistor is connected to the starting voltage terminal of the power chip; one end of the fourth capacitor is connected to the negative electrode of the seventh unidirectional diode and the other end is grounded.

[0021] The utility model has positive effects: the structure of the utility model is reasonably set up, and a rectifier, filter and current limiting circuit is arranged between the starting voltage end of the power supply chip and the AC input circuit. When the AC voltage is reduced, the voltage entering the power supply chip is stable, so that the voltage entering the power supply chip is not affected by the high-voltage DC fluctuation, and there will be no flashing light, which is beneficial to improving the stability and reliability of use, and has strong applicability and good practicality.

[0022] The standard parts used in this embodiment can be purchased directly from the market, and the non-standard structural components recorded in the specification can also be directly processed according to existing technical common sense. At the same time, the connection method of each component adopts the mature conventional means in the prior art, and the machinery, parts and equipment all adopt the conventional models in the prior art, so no specific description will be given here.

[0023] Obviously, the above embodiments of the present invention are merely examples for clearly explaining the present invention, and are not intended to limit the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. However, these obvious changes or modifications derived from the essential spirit of the present invention still belong to the protection scope of the present invention.

Claims

1. A non-isolated power supply structure with low voltage starting function, characterized in that: It includes a mains input circuit, a rectifier bridge circuit connected to the mains input circuit, a MOS tube control circuit connected to the rectifier bridge circuit, a power chip connected to the MOS tube control circuit, and a constant transformer circuit connected to the MOS tube control circuit; The control end of the power chip is connected to the constant transformer circuit; A rectifier, filter and current limiting circuit is provided between the starting voltage terminal of the power chip and the mains input circuit, and the control terminal of the MOS tube control circuit is connected to the PWM driving terminal of the power chip.

2. The non-isolated power supply structure with low voltage starting function according to claim 1, characterized in that: The rectification, filtering and current limiting circuit comprises a seventh unidirectional diode, a sixth resistor and a fourth capacitor; The anode of the seventh unidirectional diode is connected to the mains input circuit, the sixth resistor is connected in series to the cathode of the seventh unidirectional diode, and the other end of the sixth resistor is connected to the starting voltage terminal of the power chip; One end of the fourth capacitor is connected to the cathode of the seventh unidirectional diode and the other end is grounded.

3. The non-isolated power supply structure with low voltage starting function according to claim 2, characterized in that: The MOS tube in the MOS tube control circuit is an N-MOS tube.

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