A control circuit for a switching power supply

Abstract

This utility model relates to the field of power electronics technology, specifically a control circuit for a switching power supply. It includes an AC power supply, a rectifier bridge, a transformer, a PWM controller, a voltage regulator, capacitors, resistors, diodes, transistors, Zener diodes, and an optocoupler. Compared with existing technologies, this utility model uses a fixed-frequency current mode for PWM control, expanding the AC power supply's voltage input range to 90V~240V. Through the transformer, voltage regulator, and circuit feedback compensation, it outputs a 24V DC power supply with a 3A current to power the hardware circuitry of fitness equipment, providing stable and safe high current and high voltage. This utility model has the advantages of simple circuitry, resistance to damage, and reduced production and maintenance costs.

Description

Technical Field

[0001] This utility model relates to the field of power electronics technology, specifically a control circuit for a switching power supply. Background Technology

[0002] In order to provide a sufficiently stable voltage and current to the fitness equipment, ensure that a stable DC power supply is provided for the entire hardware system, and ensure the normal operation of the system, various control circuits are often used in fitness equipment.

[0003] Traditional circuits mostly have fixed input voltages, making it difficult to be compatible with a wide range of power grid fluctuations. This results in the inability to meet power supply needs in areas with unstable voltage or when facing different power supply standards, affecting the applicability of fitness equipment.

[0004] When conventional fitness equipment circuits output large currents, they are prone to voltage drift or ripple interference due to load changes or temperature fluctuations. This makes it difficult to meet the stringent requirements of fitness equipment for high power supply stability, which may lead to system malfunctions or performance degradation. Furthermore, existing overload protection relies on single threshold detection, which has a slow response speed and lacks segmented protection strategies. In the event of instantaneous overload or continuous overcurrent, it may damage circuit components and increase maintenance costs.

[0005] Therefore, it is necessary to design a control circuit for a switching power supply to achieve a wide voltage input while improving power supply stability and safety. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, this utility model provides a control circuit for a switching power supply to achieve wide voltage input while improving power supply stability and safety.

[0007] To achieve the above objectives, this utility model designs a control circuit for a switching power supply, including an AC power supply, a rectifier bridge, a transformer, a PWM controller, a voltage regulator, capacitors, resistors, diodes, transistors, Zener diodes, and an optocoupler. The live wire and neutral wire of the AC power supply are connected sequentially to the positive and negative AC input terminals of the rectifier bridge, respectively. The negative output terminal of the rectifier bridge is grounded. The positive output terminal of the rectifier bridge is divided into five paths and connected to the positive terminal of capacitor three, one end of resistor six, one end of resistor nine, one end of capacitor six, and pin 5 of the transformer, respectively. The negative terminal of capacitor three is grounded. The other end of resistor six is ​​connected in series with resistors five and four and then to pin 8 of the PWM controller. The other end of capacitor six is ​​divided into three paths and connected to the other end of resistor nine and the cathode of diode two, respectively. The cathode of diode 3 is connected, the anode of diode 2 is connected in three paths to the anode of diode 3, the drain of transistor 2, and pin 3 of the transformer, respectively. The source of transistor 2 is connected in four paths to one end of resistor 10, one end of resistor 8, one end of resistor 2, and the emitter of transistor 1, respectively. The other end of resistor 10 is grounded. The gate of transistor 2 is connected in two paths to the other end of resistor 8 and one end of resistor 7, respectively. The collector of transistor 1 is connected in two paths to the other end of resistor 7 and the cathode of diode 1, respectively. The base of transistor 1 is connected to one end of resistor 3, the other end of resistor 3 is connected in two paths to the anode of diode 1 and pin 5 of the PWM controller, respectively. The other end of resistor 2 is connected in two paths to one end of capacitor 2 and P... Pin 3 of the MW controller is connected to ground, the other end of capacitor 2 is grounded, pin 2 of the transformer is grounded, pin 1 of the transformer is split into two paths connected to one end of resistor 12 and one end of resistor 13 respectively, the other end of resistor 12 is split into two paths connected to the other end of resistor 13 and the anode of diode 5 respectively, the cathode of diode 5 is split into two paths connected to the positive terminal of capacitor 15 and one end of resistor 23 respectively, the negative terminal of capacitor 15 is grounded, the other end of resistor 23 is split into two paths connected to one end of resistor 25 and the collector of transistor 3 respectively, the other end of resistor 25 is split into three paths connected to the base of transistor 3, one end of resistor 24 and the positive terminal of Zener diode respectively, the other end of resistor 24 and the negative terminal of Zener diode are grounded, and the emitter of transistor 3 is grounded. The cathode of diode 7 is connected to the anode of diode 7. The cathode of diode 7 is connected in three ways to the positive terminal of capacitor 4, one end of capacitor 5, and pin 6 of the PWM controller. The negative terminal of capacitor 4, the other end of capacitor 5, and pin 4 of the PWM controller are grounded. Pin 2 of the PWM controller is connected in two ways to one end of resistor 11 and one end of capacitor 7. The other end of resistor 11 is connected to pin C of the optocoupler. The other end of capacitor 7 and pin E of the optocoupler are grounded. Pin A of the optocoupler is connected in two ways to one end of resistor 16 and one end of resistor 15. The other end of resistor 16 is connected in three ways to the negative terminals of capacitors 9 and 13, and the 24V power supply. The negative terminals of capacitors 9 and 13 are grounded.The other end of resistor 15 is connected in three separate paths to pin K of the optocoupler, one end of capacitor 8, and the cathode of the voltage regulator. The other end of capacitor 8 is connected in series with resistor 17, and then in four separate paths to the reference terminal of the voltage regulator, one end of resistor 21, one end of resistor 26, and one end of resistor 27. The other ends of resistor 26, resistor 27, and the anode of the voltage regulator are grounded. The other end of resistor 20 is connected in three separate paths to the 24V power supply, the positive terminal of capacitor 12, and one end of capacitor 11. The negative terminal of capacitor 12 and the other end of capacitor 11 are grounded. Pin 6 of the transformer is grounded, and pin 7 of the transformer... The first pin is divided into six connections, which are respectively connected to the anode of diode 4, the middle terminal of diode 4, the anode of diode 6, the middle terminal of diode 6, one end of capacitor 10, and one end of capacitor 14. The cathode of diode 4 is divided into seven connections, which are respectively connected to the cathode of diode 6, the 24V power supply, one end of resistor 14, one end of resistor 18, one end of resistor 19, one end of resistor 21, and one end of resistor 22. The other end of resistor 14 is divided into six connections, which are respectively connected to the other ends of resistors 18, 19, 21, and 22, the other end of capacitor 10, and the other end of capacitor 14.

[0008] The PMW controller is model NCP1271A.

[0009] The optocoupler in question is model PC817.

[0010] The voltage regulator is model TL431.

[0011] The rectifier bridge is model RS207.

[0012] The diodes 1, 2, 3, 5, and 7 are of model FR207, and the diodes 4 and 6 are of model M20F40CT.

[0013] The first transistor is model 2N3906, the second transistor is model ASA65R350E, and the third transistor is model HM882.

[0014] The transformer in question is model POT3319.

[0015] Compared with existing technologies, this invention uses a fixed-frequency current mode for PWM control, expanding the AC power input voltage range to 90V~240V. Through a transformer, voltage regulator, and circuit feedback compensation, it outputs a 24V DC power supply with a 3A current to power the hardware circuitry of the fitness equipment, providing stable and safe high current and high voltage. This invention also features a simple circuit, is less prone to damage, and reduces production and maintenance costs. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the circuit structure of this utility model.

[0017] Figure 2 This is a circuit diagram of the power supply voltage input section in the circuit of this utility model.

[0018] Figure 3 This is a circuit diagram of the working circuit section in the circuit of this utility model.

[0019] Figure 4 This is a circuit diagram of the power supply voltage feedback and compensation circuit section in the circuit of this utility model.

[0020] Figure 5 This is a circuit diagram of the power supply voltage output circuit section in the circuit of this utility model. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings.

[0022] join Figures 1-5 This utility model includes an AC power supply, a rectifier bridge, a transformer, a PWM controller, a voltage regulator, a capacitor, a resistor, a diode, a transistor, a Zener diode, and an optocoupler.

[0023] The AC power supply's input voltage range is expanded to 90V~240V. The AC power supply provides current and voltage to the rectifier bridge BR1 through the IN and COM lines. The AC power supply provides a voltage of 220VAC and a frequency of 50Hz. The live wire and neutral wire of the AC power supply are connected to the positive and negative AC input terminals of the rectifier bridge BR1, respectively. The negative output terminal of the rectifier bridge BR1 is grounded. The positive output terminal of the rectifier bridge BR1 is connected in five paths to the positive terminal of capacitor C3, one end of resistor R6, one end of resistor R9, one end of capacitor C6, and pin 5 of transformer T1. The negative terminal of capacitor C3 is grounded. The other end of resistor R6 is connected in series with resistor R5 and resistor R4, and then connected to pin 8 of the PWM controller U1. The other end of capacitor C6 is connected in three paths to the other end of resistor R9, the cathode of diode D2, and... The cathode of diode 3D3 is connected to the diode. The anode of diode 2D2 is connected in three separate paths to the anode of diode 3D3, the drain of transistor 2Q2, and pin 3 of transformer T1. The source of transistor 2Q2 is connected in four separate paths to one end of resistor 10R10, one end of resistor 8R8, one end of resistor 2R2, and the emitter of transistor 1Q1. The other end of resistor 10R10 is grounded. The gate of transistor 2Q2 is connected in two separate paths to the other end of resistor 8R8 and one end of resistor 7R7. The collector of transistor 1Q1 is connected in two separate paths to the other end of resistor 7R7 and the cathode of diode 1D1. The base of transistor 1Q1 is connected to one end of resistor 3R3. The other end of resistor 3R3 is connected in two separate paths to the anode of diode 1D1 and pin 5 of PWM controller U1. The above circuit forms a voltage input circuit.

[0024] The other end of resistor 2 R2 is split into two paths, connected to one end of capacitor 2 C2 and pin 3 of PMW controller U1 respectively. The other end of capacitor 2 C2 is grounded. Pin 2 of transformer T1 is grounded. Pin 1 of transformer T1 is split into two paths, connected to one end of resistor 12 R12 and one end of resistor 13 R13 respectively. The other end of resistor 12 R12 is split into two paths, connected to the other end of resistor 13 R13 and the anode of diode 5 D5 respectively. The cathode of diode 5 D5 is split into two paths, connected to the positive terminal of capacitor 15 C15 and one end of resistor 23 R23 respectively. The negative terminal of capacitor 15 C15 is grounded. The other end of resistor 23 R23 is split into two paths, connected to one end of resistor 25 R25 respectively. The secondary circuit is connected to the collector of transistor Q3. The other end of resistor R25 is divided into three paths and connected to the base of transistor Q3, one end of resistor R24, and the positive terminal of Zener diode ZD1. The other end of resistor R24 ​​and the negative terminal of Zener diode ZD1 are grounded. The emitter of transistor Q3 is connected to the anode of diode D7. The cathode of diode D7 is divided into three paths and connected to the positive terminal of capacitor C4, one end of capacitor C5, and pin 6 of PWM controller U1. The negative terminal of capacitor C4, the other end of capacitor C5, and pin 4 of PWM controller U1 are grounded. The above circuit forms the working circuit, and the secondary circuit ensures that the output voltage of the circuit is stable and continuous.

[0025] Pin 2 of the PMW controller U1 is connected in two paths to one end of resistor 11R11 and one end of capacitor 7C7. The other end of resistor 11R11 is connected to pin C of optocoupler U2. The other end of capacitor 7C7 and pin E of optocoupler U2 are grounded. Pin A of optocoupler U2 is connected in two paths to one end of resistor 16R16 and one end of resistor 15R15. The other end of resistor 16R16 is connected in three paths to the negative terminals of capacitors 9C9 and 13C13, and the 24V power supply. The negative terminals of capacitors 9C9 and 13C13 are grounded. The other end of resistor 15R15 is connected in three paths to pin K of optocoupler U2, one end of capacitor 8C15, and the other end of capacitor 8C15. One end of capacitor C8 is connected to the cathode of voltage regulator U3. The other end of capacitor C8 is connected in series with resistor R17 and then splits into four paths to connect to the reference terminal of voltage regulator U3, one end of resistor R20, one end of resistor R26, and one end of resistor R27. The other ends of resistor R26, R27, and voltage regulator U3 are grounded. The other end of resistor R20 is split into three paths to connect to the 24V power supply, the positive terminal of capacitor C12, and one end of capacitor C11. The negative terminal of capacitor C12 and the other end of capacitor C11 are grounded. The above circuit forms a feedback and compensation circuit to ensure that the circuit is stable at +24V power supply and adjust the voltage output in a timely manner.

[0026] Pin 6 of transformer T1 is grounded. Pin 7 of transformer T1 is connected in six separate paths to the anode of diode 4D4, the middle terminal of diode 4D4, the anode of diode 6D6, the middle terminal of diode 6D6, one end of capacitor 10C10, and one end of capacitor 14C14. The cathode of diode 4D4 is connected in seven separate paths to the cathode of diode 6D6, the 24V power supply, one end of resistor 14R14, one end of resistor 18R18, one end of resistor 19R19, one end of resistor 21R21, and one end of resistor 22R22. The other end of resistor 14R14 is connected in six separate paths to the other ends of resistors 18R18, 19R19, 21R21, 22R22, capacitor 10C10, and capacitor 14C14. The above circuit forms the power supply voltage output circuit, which mainly rectifies and filters noise, reduces ripple interference, and ensures high quality and capability of the power supply voltage.

[0027] The PMW controller U1 is model NCP1271A. The NCP1271A is a small switching power supply dedicated control circuit that uses advanced PWM control technology to achieve high-efficiency energy conversion. It also has an integrated voltage regulation control circuit to ensure the stability of the output voltage.

[0028] The optocoupler U2 is model PC817, which consists of a light-emitting diode and a phototransistor. The input is an electrical signal, which is converted into an optical signal, excited by electrical excitation, and finally converted into an electrical signal at the output.

[0029] The voltage regulator U3 is model number TL431. TL431 is a controllable parallel precision voltage regulator integrated circuit that can be used to replace the function of a Zener diode.

[0030] The rectifier bridge BR1 is model RS207. The rectifier bridge BR1 converts AC power into DC power.

[0031] Diodes D1, D2, D3, D5, and D7 are all FR207, which are fast recovery diodes with short reverse recovery times. FR207 improves the stability of the circuit in high-temperature environments and is used to assist in converting AC power to DC power signals. Diodes D4 and D6 are M20F40CT.

[0032] Transistor Q1 is a 2N3906 PNP transistor. It forms a switching control circuit with resistors R3, R7, and R8. Transistor Q2 is an ASA65R350E transistor that controls the primary energy transfer of transformer T1 under a high-frequency PWM signal, supporting high-current switching operations. Transistor Q3 is an HM882 transistor that acts as a Zener transistor, dynamically adjusting the output voltage and enhancing the transient response capability of the load.

[0033] The transformer T1 is model POT3319. Transformer T1 realizes the voltage transformation from primary to secondary through magnetic coupling, and at the same time provides electrical isolation to ensure circuit safety.

[0034] This invention employs a fixed-frequency current mode for PWM control, such as the main PWM controller U1, combined with feedback compensation circuits such as optocoupler U2 and voltage regulator U3, and filtering designs such as capacitor C10 and capacitor C14, ensuring a stable 24V 3A DC output voltage. This effectively suppresses voltage drift and ripple interference caused by load changes or temperature fluctuations. It is specifically designed for high-current electrical appliances such as sports equipment, meeting the stable power supply requirements of high-power hardware such as motors and sensors, improving the overall performance and lifespan of the equipment, and enhancing the product's market competitiveness. Through wide input, high-stability output, intelligent protection, and low-cost design, this circuit solves the pain points of traditional switching power supplies in the sports equipment field.

[0035] This invention employs a fixed-frequency current-mode PWM control, expanding the AC power input voltage range to 90V~240V. Through a transformer, voltage regulator, and circuit feedback compensation, it outputs a 24V DC power supply with a 3A current to power the hardware circuitry of the fitness equipment. This provides stable and safe high current and high voltage operation. The invention features a simple circuit, is not easily damaged, and reduces production and maintenance costs.

Claims

1. A control circuit for a switching power supply, comprising an AC power supply, a rectifier bridge, a transformer, a PWM controller, a voltage regulator, a capacitor, a resistor, a diode, a transistor, a Zener diode, and an optocoupler, characterized in that: The live and neutral wires of the AC power supply are connected sequentially to the positive and negative AC input terminals of the rectifier bridge (BR1). The negative output terminal of the rectifier bridge (BR1) is grounded. The positive output terminal of the rectifier bridge (BR1) is connected in five separate paths to the positive terminal of capacitor three (C3), one end of resistor six (R6), one end of resistor nine (R9), one end of capacitor six (C6), and pin 5 of the transformer (T1). The negative terminal of capacitor three (C3) is grounded. The other end of resistor six (R6) is connected in series with resistor five (R5) and resistor four (R4) and then to pin 8 of the PWM controller (U1). The other end of capacitor six (C6) is connected in three separate paths to the other end of resistor nine (R9), the cathode of diode two (D2), and... The cathode of diode 3 (D3) is connected. The anode of diode 2 (D2) is connected in three paths to the anode of diode 3 (D3), the drain of transistor 2 (Q2), and pin 3 of transformer (T1). The source of transistor 2 (Q2) is connected in four paths to one end of resistor 10 (R10), one end of resistor 8 (R8), one end of resistor 2 (R2), and the emitter of transistor 1 (Q1). The other end of resistor 10 (R10) is grounded. The gate of transistor 2 (Q2) is connected in two paths to the other end of resistor 8 (R8) and one end of resistor 7 (R7). The collector of transistor 1 (Q1) is connected in two paths to the other end of resistor 7 (R7) and the cathode of diode 1 (D1). The transistor is connected in two paths: the base of transistor Q1 is connected to one end of resistor R3; the other end of resistor R3 is connected in two paths to the anode of diode D1 and pin 5 of the PWM controller U1; the other end of resistor R2 is connected in two paths to one end of capacitor C2 and pin 3 of the PWM controller U1; the other end of capacitor C2 is grounded; pin 2 of transformer T1 is grounded; pin 1 of transformer T1 is connected in two paths to one end of resistor R12 and one end of resistor R13; the other end of resistor R12 is connected in two paths to the other end of resistor R13 and diode D1. The anode of diode (D5) is connected. The cathode of diode five (D5) is split into two paths, connected to the positive terminal of capacitor fifteen (C15) and one end of resistor twenty-three (R23). The negative terminal of capacitor fifteen (C15) is grounded. The other end of resistor twenty-three (R23) is split into two paths, connected to one end of resistor twenty-five (R25) and the collector of transistor three (Q3). The other end of resistor twenty-five (R25) is split into three paths, connected to the base of transistor three (Q3), one end of resistor twenty-four (R24), and the positive terminal of Zener diode (ZD1). The other end of resistor twenty-four (R24) and the negative terminal of Zener diode (ZD1) are grounded. The emitter of transistor three (Q3) is connected to the anode of diode seven (D7).The cathode of diode 7 (D7) is connected in three paths to the positive terminal of capacitor 4 (C4), one end of capacitor 5 (C5), and pin 6 of the PWM controller (U1). The negative terminal of capacitor 4 (C4), the other end of capacitor 5 (C5), and pin 4 of the PWM controller (U1) are grounded. Pin 2 of the PWM controller (U1) is connected in two paths to one end of resistor 11 (R11) and one end of capacitor 7 (C7). The other end of resistor 11 (R11) is connected to pin C of optocoupler (U2). The other end of capacitor 7 (C7) and pin E of optocoupler (U2) are grounded. Pin A of optocoupler (U2) is connected in two paths to resistor 16 (R11). One end of resistor 16 and one end of resistor 15 (R15) are connected. The other end of resistor 16 (R16) is connected in three separate paths to the negative terminals of capacitor 9 (C9), capacitor 13 (C13), and the 24V power supply. The negative terminals of capacitor 9 (C9) and capacitor 13 (C13) are grounded. The other end of resistor 15 (R15) is connected in three separate paths to the K pin of optocoupler (U2), one end of capacitor 8 (C8), and the cathode of voltage regulator (U3). The other end of capacitor 8 (C8) is connected in series with resistor 17 (R17), and then in four separate paths to the reference terminal of voltage regulator (U3), one end of resistor 20 (R20), one end of resistor 26 (R26), and resistor 2... One end of resistor 17 (R27) is connected; the other end of resistor 26 (R26), the other end of resistor 27 (R27), and the anode of voltage regulator (U3) are grounded; the other end of resistor 20 (R20) is connected in three separate paths to the 24V power supply, the positive terminal of capacitor 12 (C12), and one end of capacitor 11 (C11); the negative terminal of capacitor 12 (C12) and the other end of capacitor 11 (C11) are grounded; pin 6 of transformer (T1) is grounded; pin 7 of transformer (T1) is connected in six separate paths to the anode of diode 4 (D4), the middle terminal of diode 4 (D4), the anode of diode 6 (D6), the middle terminal of diode 6 (D6), and the capacitor 10 (C10). One end of the resistor is connected to one end of capacitor fourteen (C14). The cathode of diode four (D4) is connected in seven separate paths to the cathode of diode six (D6), the 24V power supply, one end of resistor fourteen (R14), one end of resistor eighteen (R18), one end of resistor nineteen (R19), one end of resistor twenty-one (R21), and one end of resistor twenty-two (R22). The other end of resistor fourteen (R14) is connected in six separate paths to the other ends of resistor eighteen (R18), resistor nineteen (R19), resistor twenty-one (R21), resistor twenty-two (R22), capacitor ten (C10), and capacitor fourteen (C14).

2. The control circuit for a switching power supply according to claim 1, characterized in that: The PMW controller (U1) mentioned is model NCP1271A.

3. The control circuit for a switching power supply according to claim 1, characterized in that: The optocoupler (U2) mentioned is model PC817.

4. The control circuit for a switching power supply according to claim 1, characterized in that: The voltage regulator (U3) mentioned is model TL431.

5. The control circuit for a switching power supply according to claim 1, characterized in that: The rectifier bridge (BR1) mentioned is model RS207.

6. The control circuit for a switching power supply according to claim 1, characterized in that: The diodes D1, D2, D3, D5, and D7 are of model number FR207, and the diodes D4 and D6 are of model number M20F40CT.

7. The control circuit for a switching power supply according to claim 1, characterized in that: The transistor one (Q1) is model number 2N3906, the transistor two (Q2) is model number ASA65R350E, and the transistor three (Q3) is model number HM882.

8. The control circuit for a switching power supply according to claim 1, characterized in that: The transformer (T1) is model number POT3319.

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