Switching power supply for adjusting multi-point duty ratio

Abstract

The utility model relates to the technical field of switching power supplies, and provides a switching power supply for adjusting the duty ratio of multiple points, which comprises a switching power supply main circuit, and a power correction circuit, an output voltage adjusting circuit and an output voltage stabilizing circuit which are connected with the switching power supply main circuit, the switching power supply main circuit comprises an inductor LF1, an inductor LF2, rectifiers BD1 and BD2, an inductor L2, an inductor L1, a diode D7, a resistor NTR2 and a transformer T1 which are sequentially connected from an alternating current input end to a direct current output end, a first output end of the transformer T1 outputs a direct current power supply, and a second output end of the transformer T1 is grounded through a switching tube Q7. Through the scheme, the electric energy utilization efficiency, the voltage stabilization precision and the load regulation rate of the power supply are improved, and stable and reliable direct current power supply output can be provided under various load conditions.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of switching power supply, specifically, relates to a switching power supply of multiple point duty ratio adjustment. BACKGROUND

[0002] With the continuous development of modern electronic equipment, the performance requirements of switching power supply are also getting higher and higher. Traditional switching power supply has certain limitations in power factor, voltage regulation accuracy and load regulation rate, etc., and it is difficult to meet the demand of modern electronic equipment for high-efficiency and stable power supply. Especially in some occasions with high requirements for power quality, such as data center, communication equipment and other fields, the traditional switching power supply has been unable to meet the requirements. Therefore, developing a switching power supply with high performance, high precision and high stability has become an important direction of the development of current power supply technology.

[0003] In view of the problems of traditional switching power supply in power factor, voltage regulation accuracy and load regulation rate, etc., a new type of switching power supply scheme needs to be designed. This scheme needs to solve how to improve the voltage regulation accuracy and load regulation rate while ensuring the efficient operation of the power supply, so as to meet the high requirements of modern electronic equipment for power quality. In addition, it is also necessary to consider how to reduce the harmonic pollution of the power supply and improve the power factor, so as to reduce the negative impact on the power grid. Therefore, developing a switching power supply scheme with multiple point duty ratio adjustment function has become an important way to solve the above problems. Utility model content

[0004] In order to solve the above problems, the utility model provides a switching power supply of multiple point duty ratio adjustment.

[0005] The technical scheme of the utility model is as follows:

[0006] A kind of multiple-point duty cycle regulated switching power supply, including switching power supply main circuit and the power correction circuit, output voltage regulating circuit and output voltage stabilizing circuit connected with it, the switching power supply main circuit includes the inductance LF1, inductance LF2, rectifier BD1, BD2, inductance L2, inductance L1, diode D7, resistance NTR2 and transformer T1 sequentially connected between AC input end to DC output end, the first output end of the transformer T1 outputs DC power supply, the second output end of the transformer T1 is grounded by switch tube Q7, the input end of the power correction circuit is connected the connecting point of resistance NTR2 and transformer T1 first input end, the output end of the power correction circuit is connected the connecting point of inductance L1 and diode D7, the input end of the output voltage regulating circuit is connected the DC output end, the output end of the output voltage regulating circuit is connected the second input end of the transformer T1, the second input end of the transformer T1 is connected the first input end of transformer T1 by diode D8 and resistance R61, the input end of the output voltage stabilizing circuit is connected the second output end of the transformer T1, the output end of the output voltage stabilizing circuit is used to control switch tube Q7.

[0007] Further, the power correction circuit includes power chip U1 and switch tube Q2, the FB end of the power chip U1 is sequentially connected the connecting point of resistance NTR2 and transformer T1 first input end by resistance R6, resistance R5 and resistance R4, the DRV end of the power chip U1 is sequentially connected the gate of the switch tube Q2 by resistance R2 and resistance R23, the drain of the switch tube Q2 is connected the connecting point of inductance L1 and diode D7, the source of the switch tube Q2 is grounded by resistance R19.

[0008] Further, the ISEN end of the power chip U1 is sequentially connected the connecting point of inductance L1 and diode D7 by capacitor C27 and resistance R39.

[0009] Further, the output voltage regulating circuit includes voltage chip U2, optocoupler U3 and switch tube Q8, the COMP end of the voltage chip U2 is connected the DC output end by the optocoupler U3, the DRV end of the voltage chip U2 is sequentially connected the gate of the switch tube Q8 by resistance R27 and resistance R36, the drain of the switch tube Q8 is connected the second input end of the transformer T1, the source of the switch tube Q8 is grounded by resistance R44.

[0010] Further, the first input end of the photo-coupler U3 is connected with the direct current output end through the resistor R17, the direct current output end is grounded through the resistor R31 and the resistor R35, the connecting point of the resistor R31 and the resistor R35 is connected with the control end of the thyristor diode U4, the first end of the thyristor diode U4 is connected with the second input end of the photo-coupler U3, the second end of the thyristor diode U4 is grounded, the first output end of the photo-coupler U3 is connected with the COMP end of the voltage chip U2, the second output end of the photo-coupler U3 is grounded, and the first output end of the photo-coupler U3 is grounded through the voltage stabilizing diode ZD1.

[0011] Further, the output voltage stabilizing circuit comprises a voltage chip U5, the DSEN end of the voltage chip U5 is connected with the second output end of the transformer T1 through the resistor R68, the GATE end of the voltage chip U5 is connected with the gate of the switch tube Q7 through the resistor R65, the drain of the switch tube Q7 is connected with the second output end of the transformer T1, and the source of the switch tube Q7 is grounded.

[0012] The working principle and beneficial effects of the utility model are as follows:

[0013] In the utility model, the switch power supply main circuit is used for converting AC input into DC output, the power correction circuit is used for improving the power factor, the output voltage adjusting circuit is used for adjusting the transformer input voltage according to the change of the output voltage, the output voltage stabilizing circuit is used for stabilizing the output voltage by controlling the on time of the switch tube, and multi-point duty cycle adjustment is realized.

[0014] The utility model will be explained in further detail in connection with the drawings and specific embodiments. DRAWINGS

[0015] Figure 1 It is the circuit diagram of the switch power supply main circuit in the utility model;

[0016] Figure 2 It is the circuit diagram of the power correction circuit in the utility model;

[0017] Figure 3 It is the circuit diagram of the output voltage adjusting circuit in the utility model;

[0018] Figure 4 It is the circuit diagram of the output voltage stabilizing circuit in the utility model. CONCRETE EMBODIMENT

[0019] The technical solutions of this utility model will be clearly and completely described below with reference to the embodiments of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this utility model.

[0020] Example 1

[0021] This embodiment proposes a switching power supply with multi-point duty cycle adjustment, including a main circuit of the switching power supply and a power correction circuit, an output voltage adjustment circuit and an output voltage regulator circuit connected thereto.

[0022] like Figure 1 As shown, the main circuit of the switching power supply includes inductors LF1 and LF2, rectifiers BD1 and BD2, inductors L2 and L1, diode D7, resistor NTR2, and transformer T1 connected sequentially from the AC input terminal to the DC output terminal. The first output terminal of transformer T1 outputs DC power, and the second output terminal of transformer T1 is grounded through switching transistor Q7. The input terminal of the power correction circuit is connected to the connection point of resistor NTR2 and the first input terminal of transformer T1, and the output terminal of the power correction circuit is connected to the connection point of inductor L1 and diode D7. The input terminal of the output voltage regulation circuit is connected to the DC output terminal, and the output terminal of the output voltage regulation circuit is connected to the second input terminal of transformer T1. The second input terminal of transformer T1 is connected to diode D8 and resistor R61. Specifically, in actual application circuits, resistors R52, R53, R54, R62, R63, and R64 connected in parallel with resistor R61 are also included and connected to the first input terminal of transformer T1. The input terminal of the output voltage regulator circuit is connected to the second output terminal of transformer T1, and the output terminal of the output voltage regulator circuit is used to control switching transistor Q7.

[0023] In this embodiment, the main circuit of the switching power supply is the core part of the power supply, responsible for converting AC input into DC output. Among them, the transformer T1 plays the role of isolation and transformation, its first output end outputs the DC power supply, and the second output end is connected to the ground through the switch tube Q7. The main function of the power correction circuit (PFC circuit) is to improve the power demand of the load in the circuit to the power grid, so that the power factor of the circuit is close to 1, thereby reducing the pollution to the power grid and improving the efficiency of electric energy utilization. The output voltage regulation circuit controls the size of the output voltage by adjusting the input voltage of the transformer T1. Specifically, when the output voltage changes, the output voltage regulation circuit will detect this change and change the input voltage of the transformer T1 by adjusting its output signal, thereby realizing the regulation of the output voltage. The main function of the output voltage stabilizing circuit is to stabilize the output voltage and prevent it from changing due to load changes or input voltage fluctuations. When the output voltage rises, the output voltage stabilizing circuit will detect this change and reduce the output voltage by controlling the conduction and cutoff of the switch tube Q7; conversely, when the output voltage decreases, the output voltage stabilizing circuit will increase the conduction time of the switch tube Q7 to increase the output voltage. In this way, the output voltage stabilizing circuit can ensure that the output voltage always remains within the set range.

[0024] In the switching power supply, multi-point duty cycle regulation is achieved by adjusting the input voltage of the transformer T1 and the conduction time of the switch tube Q7. Specifically, the output voltage regulation circuit and the output voltage stabilizing circuit will jointly act on the transformer T1 and the switch tube Q7, adjusting their parameters to change the duty cycle, thereby achieving precise control of the output voltage. This method can improve the voltage stabilization accuracy and load regulation rate of the power supply, so that it can maintain a stable output voltage under various load conditions.

[0025] As shown in Figure 2

[0026] The power correction circuit includes power chip U1 and switch tube Q2, the FB end of power chip U1 is connected to the connection point of resistor NTR2 and the first input end of transformer T1 through resistor R6, resistor R5 and resistor R4 in turn, the DRV end of power chip U1 is connected to the gate of switch tube Q2 through resistor R2 and resistor R23 in turn, the drain of switch tube Q2 is connected to the connection point of inductor L1 and diode D7, the source of switch tube Q2 is connected to the ground through resistor R19, and specifically, the actual application circuit also includes resistors R55 and R56 connected in parallel with resistor R19.

[0027] ​In this embodiment, the power chip U1 is the core control chip of the PFC circuit, responsible for monitoring the feedback voltage and controlling the switching action of the switch Q2, to achieve the correction of the power factor. The switch Q2 is the executive element of the power correction circuit, whose gate receives the control signal from the DRV terminal of the power chip U1, thereby controlling its conduction and cutoff. When the switch Q2 is on, it allows current to flow through the inductor L1 to the subsequent circuit; when the switch Q2 is off, it blocks the current path. Resistors R6, R5, and R4 are connected in series between the FB terminal of the power chip U1 and the connection point of resistor NTR2 and the first input terminal of the transformer T1, forming a feedback network. This feedback network is used to monitor the change of the output voltage and convert it into a feedback voltage signal input to the FB terminal of the power chip U1. Resistors R2 and R23 are connected in series between the DRV terminal of the power chip U1 and the gate of the switch Q2, for current limiting and protection of the gate of the switch Q2. The source of the switch Q2 is connected to ground through resistor R19 and parallel resistors R55 and R56, forming a discharge circuit. When the switch Q2 is off, the energy stored in the inductor L1 is released through the circuit composed of these resistors and diode D7.

[0028] Through the precise control of the power chip U1, the input current and input voltage waveforms are as synchronized as possible, thereby improving the power factor and reducing harmonic pollution to the power grid. Since the power correction circuit works in coordination with the output voltage regulation circuit and the output voltage stabilization circuit, it also helps to improve the stability of the output voltage. When the output voltage changes, the power correction circuit can quickly adjust its output current to maintain the output voltage within the set range.

[0029] Further, the ISEN terminal of the power chip U1 is connected to the connection point of the inductor L1 and the diode D7 in sequence through the capacitor C27 and the resistor R39.

[0030] In this embodiment, the ISEN terminal of the power chip U1 is used for the input terminal of the current signal. Typically, the ISEN terminal will receive a voltage signal proportional to the circuit current, which is used for current control and protection inside the power chip U1. The capacitor C27 is connected in series between the ISEN terminal and the resistor R39, which plays a role in filtering and decoupling, smoothing the high-frequency noise in the current detection signal, and ensuring that the power chip U1 receives a stable current signal. The resistor R39 is used to convert the current into a voltage signal. When current flows through the resistor R39, a voltage drop is generated across it, which is proportional to the current. This voltage signal is then sent to the ISEN terminal of the power chip U1.

[0031] The power chip U1 can accurately detect the current in the circuit through the combination of resistor R39 and capacitor C27. This is crucial for achieving power factor correction, as the power chip U1 needs to adjust the duty cycle of the switch tube Q2 according to the current signal to control the phase difference between the input current and the input voltage. When the current in the circuit exceeds the set threshold, the power chip U1 can identify the overcurrent condition through the voltage signal detected at the ISEN terminal. Once overcurrent is detected, the power chip U1 will take prompt measures (such as turning off the switch tube Q2) to protect the circuit from overcurrent damage. By precisely controlling the current signal, the power correction circuit can ensure that the waveforms of the input current and the input voltage are as synchronized as possible. Not only does this reduce harmonic pollution, but it also improves the power factor, thereby improving energy utilization efficiency.

[0032] As Figure 3 shown,

[0033] The output voltage regulation circuit includes voltage chip U2 (model SY5020A), optocoupler U3, and switch tube Q8. The COMP terminal of voltage chip U2 is connected to the DC output terminal through optocoupler U3, the DRV terminal of voltage chip U2 is connected to the gate of switch tube Q8 in turn through resistors R27 and R36, the drain of switch tube Q8 is connected to the second input terminal of transformer T1, and the source of switch tube Q8 is connected to ground through resistor R44. Specifically, the actual application circuit also includes resistors R43 and R45 connected in parallel with resistor R44.

[0034] In this embodiment, the COMP terminal of voltage chip U2 is the comparator output terminal, which is used to connect external circuits to regulate the output voltage. By connecting optocoupler U3 to the DC output terminal, the feedback signal of the output voltage can be obtained and compared with the internal reference voltage. When the output voltage deviates from the predetermined value, the COMP terminal will output an error signal to adjust the conduction state of switch tube Q8. The DRV terminal is the drive output terminal, which is used to provide the gate drive signal of switch tube Q8. This signal is divided by resistors R27 and R36 and then sent to the gate of switch tube Q8 to control its conduction and cutoff.

[0035] When the output voltage rises, optocoupler U3 will deliver more current to the COMP terminal of voltage chip U2, causing the error signal output by the COMP terminal to increase. This increased error signal is transmitted to the gate of switch tube Q8 through the DRV terminal and resistors R27 and R36, causing the conduction time of switch tube Q8 to be shortened, thereby reducing the output voltage. Conversely, when the output voltage decreases, the current delivered by optocoupler U3 decreases, and the error signal output by the COMP terminal decreases, causing the conduction time of switch tube Q8 to be extended, thereby increasing the output voltage. In this way, the circuit can automatically adjust the output voltage to keep it within a predetermined range.

[0036] Further, the first input end of the optocoupler U3 is connected to the DC output end through the resistor R17, the DC output end is connected to the ground through the resistor R31 and the resistor R35, the connecting point of the resistor R31 and the resistor R35 is connected to the control end of the thyristor diode U4, the first end of the thyristor diode U4 is connected to the second input end of the optocoupler U3, the second end of the thyristor diode U4 is connected to the ground, the first output end of the optocoupler U3 is connected to the COMP end of the voltage chip U2, the second output end of the optocoupler U3 is connected to the ground, and the first output end of the optocoupler U3 is connected to the ground through the voltage stabilizing diode ZD1.

[0037] When the DC output voltage rises, the voltage transmitted to the first input end of the optocoupler U3 through the resistor R17 also rises accordingly. This causes the light-emitting diode inside the optocoupler U3 to emit light more intensely, which in turn increases the conduction degree of the photo-sensitive triode. The voltage at the first output end of the optocoupler U3 decreases, and this change is detected by the COMP end of the voltage chip U2. The voltage chip U2 adjusts the output signal of its DRV end according to the change in the voltage at the COMP end, thereby controlling the conduction time of the switch tube Q8 to reduce the output voltage. At the same time, the rise of the DC output voltage may also cause the voltage at the connecting point of the resistors R31 and R35 to reach the trigger voltage of the thyristor diode U4, causing the U4 to conduct. This further affects the input current of the optocoupler U3, thereby accelerating the adjustment process of the output voltage. The voltage stabilizing diode ZD1 ensures that the voltage at the output end of the optocoupler U3 does not exceed its rated voltage, protecting the circuit from damage.

[0038] As shown in Figure 4

[0039] The output voltage stabilizing circuit includes the voltage chip U5, the DSEN end of the voltage chip U5 is connected to the second output end of the transformer T1 through the resistor R68, the GATE end of the voltage chip U5 is connected to the gate of the switch tube Q7 through the resistor R65, the drain of the switch tube Q7 is connected to the second output end of the transformer T1, and the source of the switch tube Q7 is connected to the ground (specifically, the actual application circuit also includes the switch tube Q6 connected in parallel with the switch tube Q7, and the connection mode is the same as that of the switch tube Q7).

[0040] ​When the GATE terminal of the voltage chip U5 outputs a high level signal, the gate voltage of the switch tube Q7 (and Q6, if present) rises, making it conduct. At this time, the current passes through the primary winding of the transformer T1, thereby generating an induced electromotive force in the secondary winding, and in turn generating an output voltage. As the output voltage rises, certain parameters of the transformer T1 (such as demagnetization time, current, etc.) will change, and these changes are transmitted to the DSEN terminal of the voltage chip U5 through the resistor R68. The voltage chip U5 adjusts the duty cycle of the PWM signal output from the GATE terminal according to the signal received by the DSEN terminal, thereby controlling the conduction time of the switch tube Q7 (and Q6), and in turn adjusting the output voltage to keep it stable. If the output voltage is too high, the voltage chip U5 will reduce the duty cycle of the PWM signal, reduce the conduction time of the switch tube, and thereby reduce the output voltage; conversely, if the output voltage is too low, the duty cycle of the PWM signal will be increased, the conduction time of the switch tube will be increased, and thereby the output voltage will be increased.

[0041] The above is only a preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A multipoint duty cycle regulated switching power supply, characterized by, The switch power supply main circuit includes inductance LF1, inductance LF2, rectifier BD1, BD2, inductance L2, inductance L1, diode D7, resistance NTR2 and transformer T1 connected in sequence from AC input end to DC output end, the first output end of the transformer T1 outputs DC power supply, the second output end of the transformer T1 is grounded through switch tube Q7, the input end of the power correction circuit is connected with the connecting point of resistance NTR2 and the first input end of transformer T1, the output end of the power correction circuit is connected with the connecting point of inductance L1 and diode D7, the input end of the output voltage regulation circuit is connected with the DC output end, the output end of the output voltage regulation circuit is connected with the second input end of the transformer T1, the second input end of the transformer T1 is connected with the first input end of the transformer T1 through diode D8 and resistance R61, the input end of the output voltage regulation circuit is connected with the second output end of the transformer T1, and the output end of the output voltage regulation circuit is used for controlling switch tube Q7.

2. A switch mode power supply for regulating a duty cycle at multiple points as claimed in claim 1, wherein, The power correction circuit includes power chip U1 and switch tube Q2, the FB end of the power chip U1 is connected with the connecting point of resistance NTR2 and the first input end of transformer T1 in sequence through resistance R6, resistance R5 and resistance R4, the DRV end of the power chip U1 is connected with the gate of the switch tube Q2 in sequence through resistance R2 and resistance R23, the drain of the switch tube Q2 is connected with the connecting point of inductance L1 and diode D7, and the source of the switch tube Q2 is grounded through resistance R19.

3. A switch mode power supply for regulating a duty cycle at multiple points as claimed in claim 2, wherein, The ISEN end of the power chip U1 is connected with the connecting point of inductance L1 and diode D7 in sequence through capacitor C27 and resistance R39.

4. A switch mode power supply for regulating a duty cycle at multiple points as claimed in claim 1, wherein, The output voltage regulation circuit includes voltage chip U2, optocoupler U3 and switch tube Q8, the COMP end of the voltage chip U2 is connected with the DC output end through the optocoupler U3, the DRV end of the voltage chip U2 is connected with the gate of the switch tube Q8 in sequence through resistance R27 and resistance R36, the drain of the switch tube Q8 is connected with the second input end of the transformer T1, and the source of the switch tube Q8 is grounded through resistance R44.

5. A switch mode power supply for regulating a duty cycle at multiple points as claimed in claim 4, wherein, The first input end of the optocoupler U3 is connected with the DC output end through resistance R17, the DC output end is grounded through resistance R31 and resistance R35, the connecting point of the resistance R31 and the resistance R35 is connected with the control end of thyristor diode U4, the first end of the thyristor diode U4 is connected with the second input end of the optocoupler U3, the second end of the thyristor diode U4 is grounded, the first output end of the optocoupler U3 is connected with the COMP end of the voltage chip U2, the second output end of the optocoupler U3 is grounded, and the first output end of the optocoupler U3 is grounded through voltage stabilizing diode ZD1.

6. A switch mode power supply for regulating a duty cycle at multiple points as claimed in claim 1, wherein, The output voltage stabilizing circuit comprises a voltage chip U5, the DSEN end of the voltage chip U5 is connected with the second output end of the transformer T1 through a resistor R68, the GATE end of the voltage chip U5 is connected with the gate of the switch tube Q7 through a resistor R65, the drain of the switch tube Q7 is connected with the second output end of the transformer T1, and the source of the switch tube Q7 is grounded.

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