Switching power supply constant power output circuit and control method thereof

Abstract

The invention discloses a switching power supply constant power output circuit and a control method thereof, and the method comprises the steps: a power conversion module converts an external alternating current into a direct current and transmits the direct current to a transformer module, and the transformer module transforms the received alternating current and transmits the transformed alternating current to a voltage output module; the MCU control module adjusts the voltage output module through the voltage adjusting module according to the working instruction; the PWM control module sends a control signal to control the low-voltage clamping circuit module to clamp the output voltage of the transformer, so as to prevent the minimum output voltage of the transformer from being lower than the input voltage of the power conversion module to damage the power conversion module; when the output voltage of the transformer is large, the PWM control module adjusts the input voltage of the power conversion module through the high-voltage compensation circuit module, so that the transformer module keeps constant-power output, the risk that an LED lamp strip circuit and a switching power supply both have overpower when the LED lamp strip works at high voltage is prevented, and the safety is high.

Description

Technical Field

[0001] The present invention relates to the technical field of switching power supplies, and in particular to a switching power supply constant power output circuit and a control method thereof. Background Art

[0002] Existing LED light strips have different structures and require different working voltages. If the LED light strip is switched, the switching power supply of the LED light strip needs to increase the working voltage supplied to the LED light strip. If the voltage of the switching power supply is increased but the current does not change, when the maximum output power of the switching power supply exceeds the preset output power of the LED light strip, the LED light strip circuit can only control the current to compensate, which easily leads to the risk of overpowering of both the LED light strip circuit and the switching power supply, thereby damaging the LED light strip circuit and the switching power supply. Summary of the invention

[0003] The present invention provides a switching power supply constant power output circuit and a control method for the switching power supply constant power output circuit, so that the switching power supply can provide constant power output for LED light strips with different operating voltages.

[0004] The technical solution of the present invention is:

[0005] A switching power supply constant power output circuit comprises: a power conversion module, the power conversion module is used to convert external alternating current into direct current and then transmit it to a transformer module; a transformer module, the transformer module is used to transmit the received voltage to a voltage output module after voltage transformation; an MCU control module, the MCU module is used to send a voltage regulation signal to the voltage regulation module according to a work instruction; a voltage regulation module, the voltage regulation module is used to regulate the voltage transmitted to the voltage output module by the transformer according to the voltage regulation signal; a voltage output module, the voltage output module is used to output a working voltage to an external device; a VCC winding module, the VCC winding module is used to sample the output voltage of the transformer module; a low voltage clamping circuit module, the low voltage clamping circuit module is used to clamp the output voltage of the transformer according to a control signal; a high voltage compensation circuit module, the high voltage compensation circuit module is used to keep the transformer module at constant power output according to the control signal; and a PWM controller module, the PWM controller module is used to receive the sampled voltage of the VCC winding module and send a control signal to the low voltage clamping circuit module and the high voltage compensation circuit module according to the sampled voltage.

[0006] Furthermore, the power conversion module includes a rectifier bridge, a capacitor C4, a capacitor C5 and a switch. The rectifier bridge is respectively connected to the external alternating current, the capacitor C4, the capacitor C5, the switch and the transformer module, and is used to convert the external alternating current into direct current and then transmit it to the transformer module. The capacitor C4 and the capacitor C5 are connected in series and are respectively connected to different pins of the rectifier bridge. One end of the switch is connected between the capacitor C4 and the capacitor C5, and the other end is connected to the rectifier bridge, and is used to switch the voltage transmitted from the power conversion module to the transformer module.

[0007] Furthermore, the voltage output module includes a voltage output terminal, a ground terminal, a diode D4 and a capacitor C2. The voltage output terminal is connected to the transformer module through the diode D4, the ground terminal is connected to the transformer module, the output terminal of the diode D4 is connected to the voltage output terminal, and the input terminal is connected to the transformer module. One end of the capacitor C2 is connected to the voltage output terminal, and the other end is connected to the ground terminal.

[0008] Furthermore, the voltage regulation module includes a transistor Q3, a resistor R7, a resistor R8, a light-emitting diode PCA, a voltage-stabilizing diode D5 and a controllable voltage-stabilizing diode U1, wherein the collector of the transistor Q3 is connected to the voltage output end, the base is connected to the output end of the voltage-stabilizing diode D5, the emitter is connected to the input end of the light-emitting diode PCA through the resistor R7, and the input end of the voltage-stabilizing diode D5 is connected to the ground end; one end of the resistor R8 is connected to the collector of the transistor Q3, and the other end is connected to the base of the transistor Q3; the output end of the light-emitting diode PCA is connected to the output end of the controllable voltage-stabilizing diode U1; the input end of the controllable voltage-stabilizing diode U1 is connected to the ground end, and the control end is connected to the MCU control module.

[0009] Furthermore, the MCU control module includes an MCU controller, a resistor R14, a resistor R15 and several pull-down resistors. The MCU controller is connected to the control end of the controllable voltage-stabilizing diode U1 through the pull-down resistor. One end of the resistor R14 is grounded, and the other end is connected to the MCU controller through the pull-down resistor. One end of the resistor R15 is connected to the voltage output end, and the other end is connected to the MCU controller through the pull-down resistor. After the pull-down resistors are connected in parallel, one end is connected to the MCU controller, and the other end is connected to the resistor R14 and the resistor R15 respectively.

[0010] Furthermore, the PWM controller module includes a PWM controller, a resistor R2, a resistor R4, a ground terminal and a field effect tube Q2. The PWM controller includes a FB pin, a CS pin and a VCC pin. The PWM controller is connected to the low voltage clamping circuit module through the FB pin, the PWM controller is connected to the high voltage compensation circuit module through the CS pin, the PWM controller is connected to the VCC winding module through the VCC pin, the gate of the field effect tube Q2 is connected to the PWM controller, the source is respectively connected to the PWM controller and the high voltage compensation circuit module through the resistor R4, the drain is connected to the transformer module, one end of the resistor R2 is connected to the source of the field effect tube Q2, and the other end is connected to the ground terminal.

[0011] Furthermore, the low voltage clamping circuit module includes a photocoupler B, a voltage regulator diode D3, a resistor R2 and a ground terminal. The voltage regulator diode D3 and the resistor R2 are connected in series and then connected in parallel with the photocoupler B, and then arranged between the FB pin of the PWM controller and the ground terminal.

[0012] Furthermore, the high voltage compensation circuit module includes a voltage stabilizing diode D2 and a resistor R5. The voltage stabilizing diode D2 and the resistor R5 are connected in series and arranged between a VCC pin and a CS pin of the PWM controller.

[0013] A control method for a switching power supply constant power output circuit, the control method is used to control the above-mentioned switching power supply constant power output circuit, the control method comprises the following steps: a power conversion module converts external alternating current into direct current and transmits it to a transformer module, the transformer module transforms the received alternating current and transmits it to a voltage output module, an MCU control module adjusts the voltage output module through a voltage adjustment module according to a work instruction; a PWM control module samples the output voltage of the transformer module through a VCC winding module, if the output voltage of the transformer module is lower than the minimum voltage input by the power conversion module, the PWM controller module clamps the output voltage of the transformer through a low voltage clamping circuit module, so that the output voltage of the transformer is greater than or equal to the minimum voltage input by the power conversion module; when the PWM control module samples that the output voltage of the transformer is greater than or equal to the set voltage, the input voltage of the power conversion module is adjusted through a high voltage compensation circuit module to keep the transformer module at constant power output.

[0014] Furthermore, the PWM control module transmits the sampled voltage sampled by the VCC winding module to its own CS pin after passing through the high voltage compensation circuit module, so as to enable the transformer module to maintain constant power output.

[0015] Compared with the prior art, the present invention includes at least the following beneficial effects: the switching power supply constant power output circuit described in the present application sends a control signal through the PWM control module to control the low voltage clamping circuit module to clamp the output voltage of the transformer, thereby preventing the minimum output voltage of the transformer from being lower than the input voltage of the power conversion module and damaging the power conversion module; when the output voltage of the transformer is large, the PWM control module adjusts the input voltage of the power conversion module through the high voltage compensation circuit module to keep the transformer module at a constant power output, thereby preventing the LED light strip from operating at a high voltage, causing the LED light strip circuit and the switching power supply to have the risk of overpower, and having higher safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic flow chart of a circuit control method of an embodiment;

[0017] Figure 2 Schematic diagram of the circuit principle of the embodiment. DETAILED DESCRIPTION

[0018] The following examples illustrate the present invention, but the present invention is not limited to these examples. Modifications to the specific embodiments of the present invention or equivalent replacement of some technical features without departing from the spirit of the present invention should be included in the scope of the technical solution claimed by the present invention.

[0019] like Figure 1 and Figure 2 As shown, a switching power supply constant power output circuit includes: a power conversion module, the power conversion module is used to convert external alternating current into direct current and then transmit it to a transformer module; a transformer module, the transformer module is used to transmit the received voltage to a voltage output module after voltage transformation; an MCU control module, the MCU module is used to send a voltage regulation signal to the voltage regulation module according to a work instruction; a voltage regulation module, the voltage regulation module is used to regulate the voltage transmitted to the voltage output module by the transformer according to the voltage regulation signal; a voltage output module, the voltage output module is used to output a working voltage to an external device; a VCC winding module, the VCC winding module is used to sample the output voltage of the transformer module; a low voltage clamping circuit module, the low voltage clamping circuit module is used to clamp the output voltage of the transformer according to a control signal; a high voltage compensation circuit module, the high voltage compensation circuit module is used to keep the transformer module at a constant power output according to a control signal; and a PWM controller module, the PWM controller module is used to receive the sampled voltage of the VCC winding module, and send a control signal to the low voltage clamping circuit module and the high voltage compensation circuit module according to the sampled voltage.

[0020] As one of the embodiments, the power conversion module includes a rectifier bridge, a capacitor C4, a capacitor C5 and a switch. The rectifier bridge is respectively connected to the external AC power, the capacitor C4, the capacitor C5, the switch and the transformer module, and is used to convert the external AC power into DC power and then transmit it to the transformer module. The capacitor C4 and the capacitor C5 are connected in series and are respectively connected to different pins of the rectifier bridge. One end of the switch is connected between the capacitor C4 and the capacitor C5, and the other end is connected to the rectifier bridge, and is used to switch the voltage transmitted from the power conversion module to the transformer module. The switch is used to switch the voltage transmitted from the power switching module to the transformer module between 110V and 220V.

[0021] As one embodiment, the voltage output module includes a voltage output end, a ground end, a diode D4 and a capacitor C2. The voltage output end is connected to the transformer module through the diode D4, the ground end is connected to the transformer module, the output end of the diode D4 is connected to the voltage output end, and the input end is connected to the transformer module. One end of the capacitor C2 is connected to the voltage output end, and the other end is connected to the ground end.

[0022] As one of the embodiments, the voltage regulation module includes a transistor Q3, a resistor R7, a resistor R8, a light-emitting diode PCA, a voltage regulator diode D5 and a controllable voltage regulator diode U1, the collector of the transistor Q3 is connected to the voltage output end, the base is connected to the output end of the voltage regulator diode D5, the emitter is connected to the input end of the light-emitting diode PCA through the resistor R7, and the input end of the voltage regulator diode D5 is connected to the ground end; one end of the resistor R8 is connected to the collector of the transistor Q3, and the other end is connected to the base of the transistor Q3; the output end of the light-emitting diode PCA is connected to the output end of the controllable voltage regulator diode U1; the input end of the controllable voltage regulator diode U1 is connected to the ground end, and the control end is connected to the MCU control module.

[0023] As one of the embodiments, the MCU control module includes an MCU controller, a resistor R14, a resistor R15 and several pull-down resistors. The MCU controller is connected to the control end of the controllable voltage-stabilizing diode U1 through the pull-down resistor. One end of the resistor R14 is grounded, and the other end is connected to the MCU controller through the pull-down resistor. One end of the resistor R15 is connected to the voltage output end, and the other end is connected to the MCU controller through the pull-down resistor. After the pull-down resistors are connected in parallel, one end is connected to the MCU controller, and the other end is connected to the resistor R14 and the resistor R15 respectively.

[0024] As one embodiment, the MCU controller pulls down the IO ports connected to the pull-down resistors to the ground in sequence, and the resistors connected in series to the IO ports are connected in parallel with the first voltage-dividing resistor R14 in sequence.

[0025] As one embodiment, by setting six groups of pull-down resistors R14, R13, R12, R11, R10, and R9, the output voltage range can be 12V, 18V, 24V, 27V, 36V, and 48V.

[0026] In some other embodiments, by setting 9 groups of pull-down resistors, the output voltage range can be 5V, 6V, 9V, 12V, 18V, 24V, 27V, 36V, and 48V, achieving the output of 9 voltages. The specific output voltage value can be matched by adjusting the resistance value of the pull-down resistor.

[0027] As one embodiment, the PWM controller module includes a PWM controller, a resistor R2, a resistor R4, a ground terminal and a field effect tube Q2. The PWM controller includes a FB pin, a CS pin and a VCC pin. The PWM controller is connected to the low voltage clamping circuit module through the FB pin, the PWM controller is connected to the high voltage compensation circuit module through the CS pin, and the PWM controller is connected to the VCC winding module through the VCC pin. The gate of the field effect tube Q2 is connected to the PWM controller, the source is respectively connected to the PWM controller and the high voltage compensation circuit module through the resistor R4, and the drain is connected to the transformer module. One end of the resistor R2 is connected to the source of the field effect tube Q2, and the other end is connected to the ground terminal.

[0028] As one embodiment, the low voltage clamping circuit module includes a photocoupler B, a voltage regulator diode D3, a resistor R2 and a ground terminal. The voltage regulator diode D3 and the resistor R2 are connected in series and then connected in parallel with the photocoupler B, and then are arranged between the FB pin of the PWM controller and the ground terminal.

[0029] As one embodiment, the high voltage compensation circuit module includes a voltage stabilizing diode D2 and a resistor R5. The voltage stabilizing diode D2 and the resistor R5 are connected in series and arranged between a VCC pin and a CS pin of a PWM controller.

[0030] A control method for a switching power supply constant power output circuit, the control method is used to control the above-mentioned switching power supply constant power output circuit, the control method comprises the following steps: a power conversion module converts external alternating current into direct current and transmits it to a transformer module, the transformer module transforms the received alternating current and transmits it to a voltage output module, an MCU control module adjusts the voltage output module through a voltage adjustment module according to a work instruction; a PWM control module samples the output voltage of the transformer module through a VCC winding module, if the output voltage of the transformer module is lower than the minimum voltage input by the power conversion module, the PWM controller module clamps the output voltage of the transformer through a low voltage clamping circuit module, so that the output voltage of the transformer is greater than or equal to the minimum voltage input by the power conversion module; when the PWM control module samples that the output voltage of the transformer is greater than or equal to the set voltage, the input voltage of the power conversion module is adjusted through a high voltage compensation circuit module to keep the transformer module at constant power output.

[0031] As one of the embodiments, the PWM control module transmits the sampled voltage sampled by the VCC winding module to its own CS pin after passing through the high voltage compensation circuit module, so as to enable the transformer module to maintain constant power output.

[0032] The constant power output circuit of the switching power supply described in the present application sends a control signal through the PWM control module to control the low voltage clamping circuit module to clamp the output voltage of the transformer, thereby preventing the minimum output voltage of the transformer from being lower than the input voltage of the power conversion module and damaging the power conversion module; when the output voltage of the transformer is large, the PWM control module adjusts the input voltage of the power conversion module through the high voltage compensation circuit module to keep the transformer module at a constant power output, thereby preventing the LED light strip circuit and the switching power supply from having the risk of overpower when the LED light strip works at a high voltage, and having a higher safety.

[0033] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A switching power supply constant power output circuit, characterized in that: include: A power conversion module, which is used to convert external alternating current into direct current and then transmit it to the transformer module; A transformer module, the transformer module is used to transform the received voltage and transmit it to the voltage output module; An MCU control module, wherein the MCU module is used to send a voltage regulation signal to the voltage regulation module according to a working instruction; A voltage regulating module, the voltage regulating module is used to regulate the voltage delivered by the transformer to the voltage output module according to the voltage regulating signal; A voltage output module, the voltage output module is used to output a working voltage to an external device; A VCC winding module, the VCC winding module is used to sample the output voltage of the transformer module; A low voltage clamping circuit module, wherein the low voltage clamping circuit module is used to clamp the output voltage of the transformer according to a control signal; A high voltage compensation circuit module, the high voltage compensation circuit module is used to keep the transformer module at a constant power output according to a control signal; The PWM controller module is used to receive the sampled voltage of the VCC winding module and send a control signal to the low voltage clamping circuit module and the high voltage compensation circuit module according to the sampled voltage.

2. The switching power supply constant power output circuit according to claim 1, characterized in that: The power conversion module includes a rectifier bridge, a capacitor C4, a capacitor C5 and a switch. The rectifier bridge is respectively connected to the external AC power, the capacitor C4, the capacitor C5, the switch and the transformer module, and is used to convert the external AC power into DC power and then transmit it to the transformer module. The capacitor C4 and the capacitor C5 are connected in series and are respectively connected to different pins of the rectifier bridge. One end of the switch is connected between the capacitor C4 and the capacitor C5, and the other end is connected to the rectifier bridge, and is used to switch the voltage transmitted from the power conversion module to the transformer module.

3. The switching power supply constant power output circuit according to claim 2, characterized in that: The voltage output module includes a voltage output terminal, a ground terminal, a diode D4 and a capacitor C2. The voltage output terminal is connected to the transformer module through the diode D4, the ground terminal is connected to the transformer module, the output terminal of the diode D4 is connected to the voltage output terminal, and the input terminal is connected to the transformer module. One end of the capacitor C2 is connected to the voltage output terminal, and the other end is connected to the ground terminal.

4. The switching power supply constant power output circuit according to claim 3, characterized in that: The voltage regulating module includes a transistor Q3, a resistor R7, a resistor R8, a light-emitting diode PCA, a voltage-stabilizing diode D5 and a controllable voltage-stabilizing diode U1. The collector of the transistor Q3 is connected to the voltage output end, the base is connected to the output end of the voltage-stabilizing diode D5, the emitter is connected to the input end of the light-emitting diode PCA through the resistor R7, and the input end of the voltage-stabilizing diode D5 is connected to the ground end; one end of the resistor R8 is connected to the collector of the transistor Q3, and the other end is connected to the base of the transistor Q3; the output end of the light-emitting diode PCA is connected to the output end of the controllable voltage-stabilizing diode U1; the input end of the controllable voltage-stabilizing diode U1 is connected to the ground end, and the control end is connected to the MCU control module.

5. The switching power supply constant power output circuit according to claim 4, characterized in that: The MCU control module includes an MCU controller, a resistor R14, a resistor R15 and several pull-down resistors. The MCU controller is connected to the control end of the controllable voltage-stabilizing diode U1 through the pull-down resistor. One end of the resistor R14 is grounded, and the other end is connected to the MCU controller through the pull-down resistor. One end of the resistor R15 is connected to the voltage output end, and the other end is connected to the MCU controller through the pull-down resistor. After the pull-down resistors are connected in parallel, one end is connected to the MCU controller, and the other end is connected to the resistor R14 and the resistor R15 respectively.

6. The switching power supply constant power output circuit according to claim 1, characterized in that: The PWM controller module includes a PWM controller, a resistor R2, a resistor R4, a ground terminal and a field effect tube Q2. The PWM controller includes an FB pin, a CS pin and a VCC pin. The PWM controller is connected to the low voltage clamping circuit module through the FB pin, the PWM controller is connected to the high voltage compensation circuit module through the CS pin, and the PWM controller is connected to the VCC winding module through the VCC pin. The gate of the field effect tube Q2 is connected to the PWM controller, the source is respectively connected to the PWM controller and the high voltage compensation circuit module through the resistor R4, and the drain is connected to the transformer module. One end of the resistor R2 is connected to the source of the field effect tube Q2, and the other end is connected to the ground terminal.

7. The switching power supply constant power output circuit according to claim 6, characterized in that: The low voltage clamping circuit module includes a photocoupler B, a voltage stabilizing diode D3, a resistor R2 and a ground terminal. The voltage stabilizing diode D3 and the resistor R2 are connected in series and then connected in parallel with the photocoupler B, and then arranged between the FB pin of the PWM controller and the ground terminal.

8. The switching power supply constant power output circuit according to claim 1, characterized in that: The high voltage compensation circuit module includes a voltage stabilizing diode D2 and a resistor R5. The voltage stabilizing diode D2 and the resistor R5 are connected in series and arranged between a VCC pin and a CS pin of a PWM controller.

9. A method for controlling a constant power output circuit of a switching power supply, characterized in that: The control method is used to control the constant power output circuit of the switching power supply according to any one of claims 1 to 8, and the control method comprises the following steps: The power conversion module converts the external AC power into DC power and transmits it to the transformer module. The transformer module transforms the received AC power and transmits it to the voltage output module. The MCU control module adjusts the voltage output module through the voltage regulation module according to the working instructions. The PWM control module samples the output voltage of the transformer module through the VCC winding module. If the output voltage of the transformer module is lower than the minimum voltage input by the power conversion module, the PWM controller module clamps the output voltage of the transformer through the low voltage clamping circuit module, so that the output voltage of the transformer is greater than or equal to the minimum voltage input by the power conversion module. When the PWM control module samples that the output voltage of the transformer is greater than or equal to the set voltage, the high voltage compensation circuit module adjusts the input voltage of the power conversion module to keep the transformer module at a constant power output.

10. The control method of the switching power supply constant power output circuit according to claim 9, characterized in that: The PWM control module transmits the sampled voltage sampled by the VCC winding module to its own CS pin after passing through the high voltage compensation circuit module to enable the transformer module to maintain constant power output.

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