A wide voltage switching power supply circuit

Abstract

This utility model discloses a wide-voltage switching power supply circuit, relating to the field of switching power supply technology, aiming to solve the problems of poor wide-voltage adaptability, unstable startup, and unreliable power supply switching in traditional circuits. It includes a power-on startup unit, a winding power supply unit, and a power chip unit. The input terminal of the power-on startup unit is connected to the initial power supply, and the output / input terminals of the three are interconnected. The power-on startup unit includes a reference voltage stabilization module and a constant current charging control module, achieving constant current startup through voltage divider regulation and the saturation region characteristics of the MOSFET. The winding power supply unit includes a rectification and filtering module and a power supply switching control module, completing the automatic switching from "startup to normal power supply". This utility model has strong wide-voltage adaptability, uninterrupted power supply switching, comprehensive circuit protection, and low energy consumption, making it suitable for scenarios requiring wide voltage input, such as photovoltaic bracket self-powered systems and industrial control equipment.

Description

Technical Field

[0001] This utility model relates to the field of switching power supply technology, and in particular to a wide voltage switching power supply circuit. Background Technology

[0002] In the field of photovoltaic power generation, the self-powered tracking control system of solar brackets relies on photovoltaic power modules to convert the wide-range DC high voltage output from the solar panels into a low-voltage power supply adapted to the system. As a core component, the power-on stability and efficiency of the switching power supply directly affect the overall performance of the system.

[0003] In the current market, the power-on startup circuits of this type of wide-voltage switching power supply generally adopt a traditional resistor series voltage divider and current-limiting scheme. This scheme uses a fixed-value resistor to divide and limit the high-voltage input current, providing startup current for the power chip. However, due to the wide-voltage input characteristics and the chip's fixed startup current requirements, this scheme has significant drawbacks: to ensure sufficient startup current at the low-voltage end, the series resistor value needs to be controlled within a small range. This leads to a sharp increase in resistor power dissipation and severe heat generation at high-voltage input, requiring the use of high-power resistors to prevent burnout and potentially affecting the lifespan of surrounding components due to high temperatures. Furthermore, the startup current varies linearly with the input voltage; insufficient current at low-voltage input causes chip startup delays, causing the system to miss the photovoltaic power generation window. Simultaneously, the startup circuit is not linked to the main power supply circuit; even after stable operation, the voltage divider and current-limiting resistor continues to consume energy, especially under high-voltage conditions, resulting in even higher additional power consumption, which contradicts the energy-saving goals of photovoltaic systems.

[0004] Existing solutions can no longer meet the system's requirements for "low heat generation, fast start-up, and low energy consumption" of switching power supplies, and there is an urgent need for new power-on startup circuits to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing switching power supplies, such as poor power-on stability, unreliable power supply switching, and narrow voltage range, and to provide a wide-voltage switching power supply circuit.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A wide-voltage switching power supply circuit includes a power-on startup unit, a winding power supply unit, and a power chip unit; the input terminal of the power-on startup unit is electrically connected to the initial power supply, and the output terminal of the power-on startup unit, the input terminal of the power chip unit, and the output terminal of the winding power supply unit are interconnected. The power-on startup unit includes a reference voltage stabilization module and a constant current charging control module. The reference voltage stabilization module includes a first resistor, a second resistor, and a second Zener diode connected in series. The input power of the constant current charging control module is divided by the first resistor and the second resistor, and the parameters are selected by the second Zener diode. The cathode of the second Zener diode is grounded. The constant current charging control module includes a third resistor, a first MOSFET, a first Zener diode, a second MOSFET, and a first capacitor connected in series. The input power of the constant current charging control module is current-limited by the third resistor and flows through the first MOSFET and the second MOSFET in sequence. Constant current control is achieved through the saturation region characteristics of the first MOSFET and the second MOSFET. The resulting constant current is transmitted to the first capacitor. A first Zener diode is connected in parallel between the gate and source of the first MOSFET.

[0007] The DC high voltage is divided by the first resistor and the second resistor and then applied to the two ends of the second Zener diode. The reference voltage is stabilized by configuring the voltage regulation parameters of the second Zener diode. At the same time, the DC high voltage is grounded through the first resistor, the second resistor, the second MOSFET, and the first capacitor. At this time, the second MOSFET is operating in saturation, and its gate-source voltage is close to its own threshold voltage.

[0008] On the other hand, the DC high voltage is connected to the first capacitor through the first resistor, the first Zener diode, and the drain and source of the second MOSFET. The first Zener diode maintains a constant voltage across its terminals through a preset voltage regulation parameter. Since the first Zener diode is connected in parallel between the gate and source of the first MOSFET, the gate-source voltage of the first MOSFET is equal to the voltage regulation value of the first Zener diode, ensuring that the first MOSFET operates in saturation.

[0009] In this state, the DC high voltage forms a charging circuit for the first capacitor through the third resistor, the drain and source path of the first MOSFET, and the ground of the first capacitor. Through the above-mentioned coordinated control, the voltage across the first capacitor quickly reaches the power supply threshold of the power chip unit, ensuring the normal startup of the power chip unit and completing the power-on startup process.

[0010] Furthermore, the winding power supply unit includes a rectifier and filter module and a power supply switching control module. The output terminal of the rectifier and filter module is connected to the input terminal of the power supply switching control module. The rectifier and filter module includes a transformer auxiliary winding, a first diode connected in series in a section of the transformer auxiliary winding, and a second capacitor connected between the negative terminal of the first diode and ground. The power supply after the transformer auxiliary winding is transformed is transmitted to the second capacitor through the first diode for filtering.

[0011] Furthermore, the power supply switching control module includes a fourth resistor, a third Zener diode, a transistor, and a second diode. The fourth resistor and the third Zener diode are connected in series between the output terminal of the rectifier and filter module and ground. The collector of the transistor is connected to the output terminal of the rectifier and filter module, and the base is interconnected with the negative terminal of the third Zener diode and one end of the fourth resistor.

[0012] During the power-on startup phase, the transistor is in the off state to avoid mutual interference between the winding power supply circuit and the power-on startup circuit, ensuring that the power-on startup unit can independently charge the first capacitor to ensure the smooth startup of the power chip unit. After the power-on startup circuit is completed, it enters the normal working mode. When the voltage output from the transformer auxiliary winding is rectified and filtered to form a stable DC voltage and reaches the set threshold, the third Zener diode breaks down in reverse. The fourth resistor provides base bias current to the transistor to make it conduct. At this time, the winding power supply circuit supplies power to the first capacitor and the power chip unit through the transistor and the second diode, completing the power supply mode switching. At the same time, the voltage regulation characteristics of the third Zener diode fix the base voltage of the transistor, and combined with its emitter junction voltage drop, stabilizes the output voltage, ensuring that the power supply voltage of the power chip unit is within the normal operating range after switching and suppressing the influence of input voltage fluctuations. In addition, the fourth resistor limits the base current of the transistor and the second diode prevents the current from flowing back in reverse, playing a loop protection role and improving the overall circuit reliability. Furthermore, the second Zener diode is connected in parallel between the gate of the second MOSFET and the negative terminal of the first capacitor to ensure a stable reference voltage is provided to the gate of the second MOSFET, thereby ensuring the accuracy of constant current charging control.

[0013] Specifically, the second Zener diode clamps its voltage at a fixed value through reverse breakdown characteristics, providing a stable gate-source voltage for the second MOSFET. Since the drain-source current of the second MOSFET is determined only by the gate-source voltage when it is operating in the saturation region, the Zener diode's voltage regulation characteristics can keep the gate-source voltage of the second MOSFET constant, unaffected by input voltage fluctuations or circuit parameter drift, thereby stabilizing the current flowing through the second MOSFET. Meanwhile, in this connection method, the gate voltage of the second MOSFET forms a fixed potential difference with the negative terminal of the first capacitor, ensuring that the gate-source voltage of the second MOSFET is always maintained at the set threshold during the charging process of the first capacitor, thus ensuring the current stability of the constant current charging circuit and providing a basis for reliable charging of the first capacitor during the power-on startup phase.

[0014] Furthermore, the cathode of the second diode is connected to one end of the first capacitor, and the anode of the second diode is connected to the emitter of the transistor, forming a connection path between the winding power supply circuit and the first capacitor in the power-on start-up circuit.

[0015] During the power-on startup phase, the transistor is in the off state, and the second diode is also off due to reverse bias, preventing reverse current from flowing from the power-on startup circuit to the winding power supply circuit and ensuring that the power-on startup unit can independently charge the first capacitor. When switching to the normal power supply mode, the transistor turns on, and the voltage generated by the winding power supply causes the second diode to conduct in the forward direction, forming a path of "winding power supply output terminal → transistor collector-emitter path → second diode forward conduction path → first capacitor energy storage circuit". This not only replenishes energy for the first capacitor but also provides continuous power to the power chip unit. At the same time, the unidirectional conductivity of the second diode prevents the first capacitor from discharging in the reverse direction to the winding power supply circuit when the voltage fluctuates, ensuring that the energy transfer direction is controllable between the two power supply phases and improving the reliability and stability of circuit switching.

[0016] Furthermore, the source of the first MOS transistor is connected to the anode of the first Zener diode, and the cathode of the first Zener diode is connected to the common connection point of the first resistor and the second resistor.

[0017] The common connection point of the first resistor and the second resistor forms a stable voltage divider node. The voltage at this node is transmitted to the first Zener diode. After being processed by the voltage regulation characteristics of the first Zener diode clamping, it provides a fixed potential to the gate of the first MOSFET, ensuring that the gate-source voltage of the first MOSFET is stable, thereby maintaining its saturation region operation state.

[0018] The advantages and beneficial effects of this invention are as follows: 1. Strong wide voltage adaptability: By combining the voltage divider and regulation design of the reference voltage stabilization module with the saturation region characteristics of the MOSFET in the constant current charging control module, accurate constant current start-up under a wide range of input voltages is achieved, avoiding start-up failures caused by input voltage fluctuations.

[0019] 2. Reliable power supply switching: The power supply switching control module in the winding power supply unit utilizes the synergistic effect of transistors and Zener diodes to achieve automatic switching between "power-on startup and normal power supply". There is no power interruption or voltage fluctuation during the switching process, ensuring the stable operation of the power chip unit.

[0020] 3. Comprehensive circuit protection: The third resistor provides current limiting protection for the constant current charging circuit, the fourth resistor protects the transistor base from excessive current impact, and the first and second diodes prevent current from flowing in reverse, thus improving the overall reliability of the circuit.

[0021] 4. High energy efficiency: During the startup phase, constant current control reduces energy loss, and during normal operation, the transformer auxiliary winding provides power, resulting in high power supply efficiency and meeting energy-saving requirements. Attached Figure Description

[0022] Figure 1 This is a block diagram of the circuit principle of the wide voltage switching power supply of this utility model; Detailed Implementation

[0023] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0024] Example 1: A wide-voltage switching power supply circuit, such as Figure 1 As shown, this embodiment is suitable for DC high voltage input scenarios with a wide range of 300V~1500V. It can be used in devices such as photovoltaic bracket self-powered systems that have high requirements for the startup stability and wide voltage adaptability of the switching power supply. The parameters of each core component are selected as follows: the first resistor R1 is a 100kΩ / 2W metal film resistor, the second resistor R2 is a 200kΩ / 2W metal film resistor, and the two are connected in series to form a voltage divider circuit; the second Zener diode ZD2 is a 4.5V Zener diode with its cathode grounded to stabilize the reference voltage; the third resistor R3... A 50kΩ / 3W current-limiting resistor is used to avoid excessive current in the constant current charging circuit; both the first MOSFET Q1 and the second MOSFET Q2 are N-channel enhancement-type MOSFETs with a gate-source threshold voltage of 4V; the first Zener diode ZD1 is a 5V Zener diode connected in parallel between the gate and source of the first MOSFET Q1; the first capacitor C1 is a 100μF / 50V electrolytic capacitor used to store energy during the startup phase; the power supply chip unit U1 is a dedicated control chip for switching power supplies with a normal operating voltage range of 10~30V.

[0025] When a 300V DC high voltage is input, the voltage is divided by the first resistor R1 and the second resistor R2, forming a 200V voltage at the common node. This voltage is applied across the second Zener diode ZD2, causing it to reverse-break down and stabilize its voltage at 4.5V. This voltage directly serves as the gate voltage of the second MOSFET Q2. At this time, the source of the second MOSFET Q2 is grounded through the first capacitor C1, and the gate-source voltage approaches its threshold voltage, causing the second MOSFET Q2 to enter saturation. Simultaneously, the voltage at the common node of the first resistor R1 and the second resistor R2 is transferred to the first Zener diode ZD1. Because the first Zener diode ZD1 is connected in parallel between the gate and source of the first MOSFET Q1, the gate-source voltage of the first MOSFET Q1 is clamped at 5V, satisfying the conduction condition and operating in the saturation region. Subsequently, the DC high voltage, after being current-limited by the third resistor R3, flows through the drain-source path of the first MOSFET Q1 to the first capacitor C1, forming a stable charging circuit. The charging current is controlled by the saturation characteristics of the first MOSFET Q1 to approximately 0.5mA. After about 200ms of charging, the voltage across the first capacitor C1 rises to 15V, reaching the startup threshold of the power chip unit. The power chip unit U1 starts working and outputs a drive signal to control the operation of the main power circuit, thus completing the power-on startup process.

[0026] When the input voltage rises to 1500V DC, the voltage division values ​​of the first resistor R1 and the second resistor R2 rise synchronously. However, the voltage regulation characteristics of the second Zener diode ZD2 keep the gate voltage of the second MOSFET Q2 at 4.5V, preventing the gate-source voltage of the second MOSFET Q2 from fluctuating with the input voltage. At the same time, the first Zener diode ZD1 continuously stabilizes the gate-source voltage of the first MOSFET Q1 at 5V, ensuring that the first MOSFET Q1 always operates in the saturation region, and the charging current is kept at about 0.5mA. This achieves constant current startup over a wide voltage input range, effectively solving the problems of excessive power consumption of resistors under high voltage input and insufficient startup current under low voltage input, which leads to chip startup delay. This ensures stable startup and operation of the switching power supply under different input voltage conditions.

[0027] Example 2: This embodiment is adapted to DC input scenarios with a wide range of 400V~1200V in industrial control equipment. It focuses on the functional implementation of the winding power supply unit, and the core component parameters are selected as follows: In the winding power supply unit, the transformer auxiliary winding T1B is designed with a turns ratio of 1:0.15, with the input side adapted to the high voltage of the main circuit and the output side capable of outputting DC alternating voltage of 60V~180V; the first diode D1 is a fast recovery diode with a reverse withstand voltage ≥200V to ensure rectification efficiency and withstand voltage safety; the second capacitor C2 is... A 220μF / 100V electrolytic capacitor is used to filter out the pulsation component after rectification; in the power supply switching control module, the fourth resistor R4 is a 20kΩ / 1W metal film resistor, the third Zener diode ZD3 is a 5.1V Zener diode, the transistor Q3 is an NPN silicon transistor with a current amplification factor β=100~200, the second diode D2 is a Schottky diode with a forward voltage drop ≤0.5V to reduce conduction losses; the first capacitor C1 is a 100μF / 50V electrolytic capacitor.

[0028] During the power-on startup phase, the power chip unit U1 is not yet operational. The transformer auxiliary winding T1B has no alternating voltage output, the rectifier and filter module has no DC voltage output, and the base of transistor Q3 has no bias current and is in a cutoff state. At this time, the winding power supply circuit is completely isolated from the power-on startup circuit, preventing current shunting or loop interference when the power-on startup unit charges the first capacitor C1. This ensures that the power-on startup unit can independently charge the first capacitor C1 through the constant current charging circuit until the voltage across the first capacitor C1 reaches the 10V startup threshold of the power chip unit U1. Then, the power chip unit U1 begins to operate, the power-on startup phase ends, and the circuit enters normal operating mode.

[0029] After entering normal operating mode, the power chip unit U1 outputs a drive signal to control the operation of the main power circuit. The energy of the transformer main winding is coupled to the auxiliary winding T1B, which outputs a DC alternating voltage of 60V~180V. This voltage is rectified into a unidirectional pulsating DC by the first diode D1, and then filtered by the second capacitor C2 to form a smooth and stable DC voltage of 55V~170V. This voltage is applied to the series branch of the fourth resistor R4 and the third Zener diode ZD3. When the voltage reaches the 5.1V reverse breakdown threshold of the third Zener diode ZD3, the third Zener diode ZD3 reverse breaks down and maintains a constant voltage of 5.1V across its terminals. This voltage serves as the base bias voltage of the transistor Q3. After the base of transistor Q3 receives bias current, it turns on. The DC voltage output by the rectifier and filter module is transmitted to the first capacitor C1 and the power chip unit U1 through the collector-emitter path of transistor Q3 and the forward conduction path of the second diode D2. On the one hand, it replenishes the energy of the first capacitor C1 and maintains its voltage at both ends within the operating voltage range of the power chip unit U1; on the other hand, it directly supplies power to the power chip, replacing the power-on startup unit to complete the continuous power supply. During this period, the voltage regulation characteristics of the third Zener diode ZD3 ensure that the base voltage of transistor Q3 is not affected by the output voltage fluctuations of the rectifier and filter module. Combined with the fixed voltage drop of 0.7V at the emitter junction of transistor Q3, the emitter output voltage of transistor Q3 is stabilized, ensuring the stable supply voltage of power chip U1. The fourth resistor R4 limits the base current of transistor Q3 to prevent excessive current from burning out the base-emitter junction of transistor Q3. The unidirectional conductivity of the second diode D2 prevents the current from the first capacitor C1 or the power chip U1 side from flowing back to the winding power supply circuit, avoiding component damage and improving the overall reliability and operational stability of the circuit power supply switching.

[0030] Example 3: This embodiment is applicable to wide voltage input scenarios of DC 200V~1000V in communication equipment. It focuses on optimizing the coordinated control of the power-on unit and the power supply switching link. The core parameters are configured as follows: The second Zener diode ZD2 is a 3.6V Zener diode, which is connected in parallel between the gate of the second MOSFET Q2 with a threshold voltage of 3.0V and the negative terminal of the first capacitor C1 (100μF / 50V); the second diode D2 is a Schottky diode with a forward voltage drop of 0.4V, with its anode connected to the emitter of the transistor Q3 and its cathode connected to the positive terminal of the first capacitor C1; the source of the first MOSFET Q1 is connected to the anode of the first Zener diode ZD1, and the cathode of ZD1 is connected to the common connection point of the first resistor R1 (80kΩ) and the second resistor R2 (160kΩ).

[0031] During the power-on startup phase, the 200V DC input voltage is divided by the first resistor R1 and the second resistor R2, resulting in a common node voltage of approximately 133.3V. This voltage is clamped to 4.7V by the first Zener diode ZD1, providing a stable gate voltage for the first MOSFET Q1 and ensuring that Q1 operates in the saturation region. Simultaneously, the second Zener diode ZD2 stabilizes the gate-source voltage of the second MOSFET Q2 at 3.6V, ensuring that Q2 also operates in the saturation region. At this time, the input voltage, after being current-limited by the third resistor R3 (40kΩ), charges the first capacitor C1 through the drain-source path of the first MOSFET Q1 and the second MOSFET Q2. Since the drain-source current of the first MOSFET Q1 and the second MOSFET Q2 is determined by their respective gate-source voltages, the charging current remains stable at around 0.6mA and is unaffected by input voltage fluctuations.

[0032] When the voltage across the first capacitor C1 rises to 12V, the power chip starts up and drives the main circuit. The output voltage of the transformer auxiliary winding is rectified and filtered to form a stable DC 50V voltage. This voltage is divided by the fourth resistor R4 (15kΩ) and the third Zener diode ZD3 (5.6V). After the third Zener diode ZD3 breaks down, it provides a 5.6V base voltage to the transistor Q3, causing the transistor Q3 to conduct. At this time, the winding supply voltage is transmitted to the first capacitor C1 and the power chip through the collector-emitter junction of the transistor Q3 and the forward path of the second diode D2. The forward conduction of the second diode D2 ensures that energy is transferred unidirectionally to the first capacitor C1, maintaining its voltage stable at around 15V. During the power-on startup phase, because the transistor Q3 is cut off and the second diode D2 is reverse biased, it effectively prevents the charging current of the first capacitor C1 from flowing back into the winding circuit, ensuring that all the energy during the startup phase is used for energy storage in the first capacitor C1.

[0033] When the input voltage rises to DC 1000V, the voltage division values ​​of the first resistor R1 and the second resistor R2 increase synchronously. However, the first Zener diode ZD1 and the second Zener diode ZD2 stabilize the gate-source voltages of the first MOSFET Q1 and the second MOSFET Q2 at 4.7V and 3.6V respectively, so that the charging current remains at 0.6mA, avoiding a surge in current under high voltage. At the same time, the unidirectional conductivity of the second diode D2 ensures that the energy transfer direction is controllable. Combined with the third Zener diode ZD3 stabilizing the base voltage of the transistor Q3, there is no voltage fluctuation during the power supply switching process, achieving stable startup and reliable power supply over a wide voltage range.

[0034] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A wide-voltage switching power supply circuit, characterized in that, It includes a power-on start-up unit, a winding power supply unit, and a power chip unit (U1); the input terminal of the power-on start-up unit is electrically connected to the initial power supply, and the output terminal of the power-on start-up unit, the input terminal of the power chip unit (U1), and the output terminal of the winding power supply unit are interconnected. The power-on startup unit includes a reference voltage stabilization module and a constant current charging control module. The reference voltage stabilization module includes a first resistor (R1), a second resistor (R2), and a second Zener diode (ZD2) connected in series. The input power of the constant current charging control module is divided by the first resistor (R1) and the second resistor (R2) and then the parameters are selected by the second Zener diode (ZD2). The cathode of the second Zener diode (ZD2) is grounded. The constant current charging control module includes a third resistor (R3), a first MOSFET (Q1), a first Zener diode (ZD1), a second MOSFET (Q2), and a first capacitor (C1) connected in series. The input power of the constant current charging control module is current-limited by the third resistor (R3) and flows through the first MOSFET (Q1) and the second MOSFET (Q2) in sequence, forming a constant current that is transmitted to the first capacitor (C1). The first Zener diode (ZD1) is connected in parallel between the gate and source of the first MOSFET (Q1).

2. The wide-voltage switching power supply circuit according to claim 1, characterized in that, The winding power supply unit includes a rectifier and filter module and a power supply switching control module. The output terminal of the rectifier and filter module is connected to the input terminal of the power supply switching control module. The rectifier and filter module includes a transformer auxiliary winding (T1B), a first diode (D1) connected in series in a section of the transformer auxiliary winding (T1B), and a second capacitor (C2) connected between the negative terminal of the first diode (D1) and ground. The power supply after the transformer auxiliary winding is transformed is transmitted to the second capacitor (C2) for filtering through the first diode (D1).

3. The wide-voltage switching power supply circuit according to claim 2, characterized in that, The power supply switching control module includes a fourth resistor (R4), a third Zener diode (ZD3), a transistor (Q3), and a second diode (D2). The fourth resistor (R4) and the third Zener diode (ZD3) are connected in series between the output terminal of the rectifier and filter module and ground. The collector of the transistor (Q3) is connected to the output terminal of the rectifier and filter module, and the base is interconnected with the negative terminal of the third Zener diode (ZD3) and one end of the fourth resistor (R4).

4. The wide-voltage switching power supply circuit according to claim 1, characterized in that, The second Zener diode (ZD2) is connected in parallel between the gate of the second MOSFET (Q2) and the negative terminal of the first capacitor (C1).

5. A wide-voltage switching power supply circuit according to claim 3, characterized in that, The cathode of the second diode (D2) is connected to one end of the first capacitor (C1), and the anode of the second diode (D2) is connected to the emitter of the transistor (Q3).

6. A wide-voltage switching power supply circuit according to claim 1, characterized in that, The source of the first MOS transistor (Q1) is connected to the anode of the first Zener diode (ZD1), and the cathode of the first Zener diode (ZD1) is connected to the common connection point of the first resistor (R1) and the second resistor (R2).

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