Switching power supply circuit and electronic equipment

Abstract

The utility model provides a switching power supply circuit and electronic equipment, and relates to the technical field of switching power supplies. The switching power supply circuit comprises a control module, a transformer, a feedback module and a plurality of output modules, the transformer comprises a primary side and a secondary side, the primary side is electrically connected with the control module and a power supply, and the secondary side is electrically connected with the feedback module and the plurality of output modules; wherein the plurality of output modules are used for outputting different voltages; the feedback module comprises an RC compensation network, the gain margin of the RC compensation network is larger than 10 dB, and the phase margin is larger than 45 degrees. The switching power supply circuit and the electronic equipment provided by the utility model have the advantage of preventing instability or oscillation of a loop.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of switching power supply, in particular to a switching power supply circuit and an electronic device. BACKGROUND

[0002] Modern air conditioning systems play a key role in providing environmental temperature and comfort control, especially the emergence of variable frequency air conditioners not only meets the adjustment of environmental temperature, but also actively responds to energy saving and emission reduction to improve the utilization rate of electric energy, and the switching power supply circuit is an indispensable component.

[0003] The switching power supply circuit provides a direct current power supply for controlling the key devices required in the variable frequency process of the air conditioner, such as IPM, IGBT and other power devices, and the application of the switching power supply in the air conditioner not only improves the power conversion efficiency, saves energy, but also significantly improves the reliability and stability of the system. By providing stable voltage, multiple output voltages and protection functions, the switching power supply ensures that each component of the air conditioner can operate in the best state, improving overall performance and user experience.

[0004] However, the switching power supply circuit in the prior art has an unstable feedback loop, which may cause unstable DC output or oscillation of the power supply. SUMMARY

[0005] The purpose of the present application is to provide a switching power supply circuit and an electronic device to solve the problem of unstable feedback loop of the switching power supply circuit in the prior art, which may cause unstable DC output or oscillation of the power supply,

[0006] To solve the above problems, on the one hand, the present application provides a switching power supply circuit, which comprises a control module, a transformer, a feedback module and a plurality of output modules, the transformer comprises a primary side and a secondary side, the primary side is electrically connected with the control module and a power supply, and the secondary side is electrically connected with the feedback module and the plurality of output modules; wherein,

[0007] The plurality of output modules are used to output different voltages.

[0008] The feedback module comprises an RC compensation network, the gain margin of the RC compensation network is greater than 10dB, and the phase margin is greater than 45 degrees.

[0009] Since the gain margin of the RC compensation network provided by the present application is greater than 10dB, and the phase margin is greater than 45 degrees, the feedback loop has sufficient gain margin and phase margin, and the gain margin and phase margin are large, so the probability of oscillation or instability of the loop is lower, thereby preventing the loop from being unstable and oscillating.

[0010] Optionally, the RC compensation network comprises a compensation resistor and a compensation capacitor, and the compensation resistor is connected with the compensation capacitor.

[0011] The resistance of the compensation resistor is 45KΩ-55KΩ, and the capacitance of the compensation capacitor is 0.045μF-0.05μF.

[0012] Optionally, the resistance of the compensation resistor is 51KΩ, and the capacitance of the compensation capacitor is 0.047μF. By setting the specific resistance and capacitance, the capacitance integral time can be reduced, the gain can be increased, and the feedback speed is improved.

[0013] Optionally, the secondary side comprises different output windings, the output module is connected with the different output windings, and the switching power supply circuit further comprises an output maintaining module, and the output maintaining module is connected between the output windings with different voltage amplitudes.

[0014] Optionally, the output windings comprise a 12V output winding and a 6V output winding, and the output maintaining module is connected in series between the 12V output winding and the 6V output winding.

[0015] Optionally, the output module connected with the 6V output winding comprises a low dropout regulator, an input end of the low dropout regulator is connected with the 6V output winding, and an output end of the low dropout regulator is used for connecting a load; the low dropout regulator is used for stabilizing the voltage at the input end to 3.3V and outputting.

[0016] Optionally, the output maintaining module comprises a resistor or a zener diode.

[0017] When the output maintaining module comprises the resistor, one end of the resistor is connected with the output winding with high voltage amplitude, and the other end of the resistor is connected with the output winding with low voltage amplitude.

[0018] When the output maintaining module comprises the zener diode, a cathode of the zener diode is connected with the output winding with high voltage amplitude, and an anode of the zener diode is connected with the output winding with low voltage amplitude.

[0019] Optionally, the feedback module further comprises an adjustable precision voltage stabilizer, an optocoupler, a voltage dividing component and a current limiting component, the optocoupler comprises a light emitting diode and a light receiving triode, the light receiving triode is connected with the control module, one end of the current limiting component is connected with the secondary side and an anode of the light emitting diode, the other end of the current limiting component is connected with a cathode of the light emitting diode and a cathode of the adjustable precision voltage stabilizer respectively, an anode of the adjustable precision voltage stabilizer is grounded, a first end of the voltage dividing component is connected with the secondary side, a second end of the voltage dividing component is connected with one end of the RC compensation network and a reference electrode of the adjustable precision voltage stabilizer, the other end of the RC compensation network is connected with the cathode of the adjustable precision voltage stabilizer, and a third end of the voltage dividing component is grounded.

[0020] The adjustable precision voltage stabilizer can ensure that the fluctuation is stably fed back to the control module, and at the same time, good temperature stability and low noise performance are provided for the switching power supply, so as to ensure stable operation of the power supply.

[0021] Optionally, the voltage dividing component comprises a first resistor, a second resistor and a third resistor, the feedback module further comprises a fourth resistor, one end of the current limiting component is connected to the secondary side through the fourth resistor, one end of the first resistor, the second resistor and the third resistor in series is a first end, the other end is a third end, and a second end is between the second resistor and the third resistor.

[0022] In another aspect, the embodiment of the present application further provides an electronic device, which comprises a load and the switching power supply circuit, the load is connected with the output module of the switching power supply circuit and is powered by the switching power supply circuit. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The simulation schematic diagram of the switching power supply circuit provided in the prior art.

[0024] Figure 2 The circuit schematic diagram of the switching power supply circuit provided in the embodiment of the present application.

[0025] Figure 3 Another circuit schematic diagram of the switching power supply circuit provided in the embodiment of the present application.

[0026] Figure 4 The simulation schematic diagram of the switching power supply circuit provided in the embodiment of the present application.

[0027] BRIEF DESCRIPTION OF DRAWINGS

[0028] 110 - control module; 120 - transformer; 130 - feedback module; 131 - RC compensation network; 132 - adjustable precision voltage regulator; 140 - output module; IC2 - optocoupler; R1 - first resistor; R2 - second resistor; R3 - third resistor; R4 - fourth resistor; R5 - current limiting component; R6 - compensation resistor; C1 - compensation capacitor. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0030] As described in the background, the feedback loop of the existing switching power supply circuit is unstable, which may cause the output DC of the power supply to be unstable or oscillate.

[0031] The existing switching power supply circuit generally includes a switching power supply management chip and a transformer, and the power supply is powered by 310V DC. The transformer and the switching power supply management chip can output 15V, 12V, 6V and 5V DC power supplies, and then output 5V and 3.3V DC power supplies through an LDO.

[0032] When simulating the switching power supply circuit, as shown in Figure 1 , when the switching power supply starts to work, the output DC will drop to 0V instantaneously after rising to a certain voltage. As shown in Figure 2 , for 6V and 3.3V DC power supplies, when they output, the output voltage will drop to 0V instantaneously after rising from 0V to 6V or 3.3V, resulting in unstable output DC of the power supply.

[0033] For air conditioners, unstable output DC of the power supply will cause various components of the air conditioner to not work in the best state, and will have the following effects on the operation of the air conditioning system:

[0034] 1. Control system failure: The control system inside the air conditioner (including microcontrollers, sensors, display screens, etc.) relies on a stable DC power supply to work. If the power supply is unstable, it may cause the control system to fail, resulting in problems such as the air conditioner failing to start normally, shutting down, and abnormal switching of operating modes.

[0035] 2. Inaccurate temperature regulation: Unstable power supply may cause temperature sensors to read incorrectly, affecting the air conditioner's temperature regulation function. This will result in inaccurate control of indoor temperature and a decrease in user experience.

[0036] 3. Damage to motors and compressors: The fan motor and compressor of the air conditioner require a stable DC power supply to drive. Unstable power supply may cause the motor to run abnormally, resulting in problems such as noise, vibration or overheating, and in severe cases, may even cause the motor to burn out or the compressor to be damaged.

[0037] 4. Shortened life of electronic components: Frequent voltage fluctuations can cause stress on the internal electronic components of the air conditioner, shortening their service life. This includes components such as capacitors, resistors, transistors, etc., which are prone to failure in a long-term unstable power supply environment.

[0038] 5. Frequent action of protection circuit: The air conditioner usually contains various protection circuits, such as overvoltage protection, overcurrent protection, and short circuit protection. If the power supply is unstable, these protection circuits may act frequently, causing the air conditioner to frequently restart or shut down, affecting normal use.

[0039] 6. Increased electromagnetic interference: Unstable DC power supply may cause electromagnetic interference (EMI), affecting the operation of the air conditioner's electronic control system, and even possibly interfering with the normal operation of other household appliances.

[0040] 7. Reduced efficiency: Unstable power supply can cause the air conditioner to run in suboptimal conditions, reducing cooling or heating efficiency, increasing energy consumption, and leading to increased electricity costs.

[0041] 8. Reduced safety in use: Unstable power supply may cause some safety hazards, such as overheating, sparking, short circuit, etc., increasing the risk of using the air conditioner.

[0042] Therefore, the embodiments of the present application provide a switching power supply circuit to solve the problem of unstable DC output or oscillation of the power supply.

[0043] The switching power supply circuit provided by the present application is described below:

[0044] As an optional implementation, please refer to Figure 2 The switching power supply circuit includes a control module 110, a transformer 120, a feedback module 130, and a plurality of output modules 140. The transformer 120 includes a primary side and a secondary side. The primary side is electrically connected to the control module 110 and the power supply. The secondary side is electrically connected to the feedback module 130 and the plurality of output modules 140. The plurality of output modules 140 are used to output different voltages. The feedback module 130 includes an RC compensation network 131. The gain margin of the RC compensation network 131 is greater than 10 dB, and the phase margin is greater than 45 degrees.

[0045] The working principle of the switching power supply circuit provided by the present application is as follows:

[0046] The control module 110 can adopt a switching power management chip, which can output different duty cycles, transform the working according to the duty cycle, and output different direct current power through a plurality of output modules 140, including 15V, 12V, 6V, 5V direct current power in the application. At the same time, the feedback module 130 will collect the voltage of the secondary side of the transformer 120, and feed back the collected information to the control module 110, and the control module 110 adjusts the duty cycle according to the information to output stable direct current power.

[0047] On this basis, the applicant found that the switching power supply feedback loop is unstable for the following reasons:

[0048] 1. Improper feedback compensation: Improper RC compensation network 131 design can lead to insufficient loop gain and phase margin, which may cause oscillation or instability.

[0049] 2. Loop delay: Feedback signal delay may cause the loop to fail to adjust the output in time, resulting in poor transient response or excessive feedback path due to improper PCB layout, increasing delay and noise.

[0050] 3. Noise and interference: External interference may affect the loop performance through the feedback path, causing output voltage fluctuation.

[0051] 4. Component mismatch: Inaccurate resistance and capacitance values in the error amplifier or feedback network can cause feedback control failure. In addition, component parameters change with temperature, and compensation is not performed, which can cause output instability.

[0052] 5. Reference voltage instability: TLM431 reference voltage source instability can directly affect the accuracy of feedback control.

[0053] Therefore, the parameters of the feedback module 130 are adjusted in the application to make the output of the switching power supply more stable, and to provide more stable voltage for the normal operation of the air conditioner.

[0054] First, the parameters of the RC compensation network 131 are adjusted. Among them, the gain margin of the RC compensation network 131 is greater than 10dB, and the phase margin is greater than 45 degrees, to ensure the stability of the feedback loop and prevent loop instability and oscillation. In addition, a high-precision error amplifier can be selected in the feedback circuit to reduce the deviation and noise introduced by the error amplifier itself. Such as 431 voltage stabilizer and other devices, eliminate the loop instability phenomenon caused by device reasons. At the same time, the feedback path can be optimized, and the feedback path can be shortened as much as possible in the PCB design wiring to reduce the influence of parasitic inductance and capacitance, improve the response speed and stability.

[0055] On this basis, as an implementation manner, the RC compensation network 131 comprises a compensation resistor R6 and a compensation capacitor C1, the compensation resistor R6 is connected with the compensation capacitor C1; the resistance value of the compensation resistor R6 is 45KΩ-55KΩ; the capacitance value of the compensation capacitor C1 is 0.045μF-0.05μF. For example, the resistance value of the compensation resistor R6 is 51KΩ; the capacitance value of the compensation capacitor C1 is 0.047μF.

[0056] In the RC compensation network 131 in the prior art, the capacitance is generally 0.1μF, and the resistance is generally 10KΩ. However, by setting the resistance value of the compensation resistor R6 to 51KΩ and the capacitance value of the compensation capacitor C1 to 0.047μF, the feedback speed can be made faster. The negative feedback circuit is a transfer function, the compensation resistor R6 is equivalent to gain, the compensation capacitor C1 is equivalent to integral time, increasing the compensation resistor R6 of the feedback loop is equivalent to increasing the gain of amplification, and reducing the compensation capacitor C1 is equivalent to reducing the integral time. Increasing the gain and reducing the integral time can both accelerate the response time of the operational amplifier to the input disturbance. Therefore, by reducing the capacitance value of the feedback capacitor, the integral time can be reduced, and by increasing the resistance value of the feedback resistor, the gain can be increased, so as to ensure the speed of the negative feedback and improve the waveform at the output end during power-on.

[0057] In addition, the feedback module 130 further comprises an adjustable precision voltage stabilizer 132, an optocoupler IC2, a voltage dividing assembly, and a current limiting component R5. The optocoupler IC2 comprises a light-emitting diode and a light-receiving triode, the light-receiving triode is connected with the control module 110, one end of the current limiting component R5 is connected with the secondary side and the anode of the light-emitting diode, the other end of the current limiting component R5 is respectively connected with the cathode of the light-emitting diode and the cathode of the adjustable precision voltage stabilizer 132, the anode of the adjustable precision voltage stabilizer is grounded, the first end of the voltage dividing assembly is connected with the secondary side, the second end of the voltage dividing assembly is connected with one end of the RC compensation network 131 and the reference electrode of the adjustable precision voltage stabilizer 132, the other end of the RC compensation network 131 is connected with the cathode of the adjustable precision voltage stabilizer 132, and the third end of the voltage dividing assembly is grounded.

[0058] The voltage dividing assembly comprises a first resistor R1, a second resistor R2, and a third resistor R3, and the feedback module 130 further comprises a fourth resistor R4. One end of the current limiting component R5 is connected to the secondary side through the fourth resistor R4, one end of the first resistor R1, the second resistor R2, and the third resistor R3 after being connected in series serves as the first end, the other end serves as the third end, and the second end is located between the second resistor R2 and the third resistor R3.

[0059] As Figure 2In the embodiment, the pin A of the opto-coupler IC2 is connected to 12V, and the pin K is connected to the cathode of the adjustable precision voltage stabilizing source 132. The adjustable precision voltage stabilizing source 132 can provide a precise and stable voltage for the pin K, so that the fluctuation of the DC output source 12V can be stably fed back to the feedback module 130, and at the same time, the adjustable precision voltage stabilizing source 132 can provide good temperature stability and low noise performance for the switching power supply, so as to ensure the stable operation of the power supply, and then the purpose of improving the waveform can be achieved by using the adjustable precision voltage stabilizing source 132 with high precision.

[0060] In addition, please refer to Figure 3 The secondary side includes different output windings, and the output module 140 is connected to the different output windings. The switching power supply circuit further includes an output maintaining module, which is connected between the output windings with different voltage amplitudes. The voltage of the DC output end of the switching power supply may rise and then drop. By setting the output maintaining module, the stability of the voltage of each DC output end can be ensured.

[0061] It should be noted that the applicant has found that a small-voltage power supply is more likely to have a situation of power-off to OV after power-on. For example, Figure 1 In the embodiment, the switching power supply circuit is more likely to have a situation of power-off to OV of the 6V and 3.3V DC power supplies after power-on. Therefore, in the present application, the output windings include a 12V output winding and a 6V output winding, and the output maintaining module is connected in series between the 12V output winding and the 6V output winding. The output module 140 connected to the 6V output winding includes a low-dropout voltage regulator, the input end of the low-dropout voltage regulator is connected to the 6V output winding, and the output end of the low-dropout voltage regulator is used to connect a load; the low-dropout voltage regulator is used to stabilize the input end voltage to 3.3V and output.

[0062] The output maintaining module includes a resistor or a voltage stabilizing diode; when the output maintaining module includes a resistor, one end of the resistor is connected to the output winding with a high voltage amplitude, and the other end of the resistor is connected to the output winding with a low voltage amplitude; when the output maintaining module includes a voltage stabilizing diode, the cathode of the voltage stabilizing diode is connected to the output winding with a high voltage amplitude, and the anode of the voltage stabilizing diode is connected to the output winding with a low voltage amplitude.

[0063] By connecting a voltage stabilizing diode or a resistor in series between the transformer 120 and the 6V output winding, the voltage stabilizing diode or the resistor can ensure that the output voltage 6V is supplied by the output voltage 12V when the voltage drops, so as to ensure the stability of the DC voltage stabilizing source 3.3V for supplying power to the air conditioner MCU in the later stage, and optimize the output waveform of the DC power supply. The simulation schematic diagram of the optimized switching power supply circuit is shown in Figure 4 .

[0064] It can be seen that the application can ensure the stability of the output DC power supply end as much as possible, reduce the influence of the power supply on the air conditioning system, and then ensure the accurate control of the air conditioner controller on each load by increasing the feedback speed, adding resistors or voltage stabilizing diodes at two different output ends.

[0065] In conclusion, the embodiment of the application provides a switching power supply circuit and an electronic device. The switching power supply circuit comprises a control module, a transformer, a feedback module and a plurality of output modules. The transformer comprises a primary side and a secondary side. The primary side is electrically connected with the control module and a power supply. The secondary side is electrically connected with the feedback module and the plurality of output modules. The plurality of output modules are used to output different voltages. The feedback module comprises an RC compensation network. The gain margin of the RC compensation network is greater than 10 dB, and the phase margin is greater than 45 degrees. Since the gain margin of the RC compensation network provided by the application is greater than 10 dB, and the phase margin is greater than 45 degrees, the feedback loop has sufficient gain margin and phase margin, and the gain margin and the phase margin are large, so the probability of oscillation or instability of the loop is low, thereby preventing the loop from being unstable and oscillating.

[0066] Although the application is disclosed as above, the application is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the application. Therefore, the protection scope of the application should be subject to the scope defined by the claims.

Claims

1. A switching power supply circuit, characterized by comprising: The switching power supply circuit comprises a control module (110), a transformer (120), a feedback module (130) and a plurality of output modules (140), the transformer (120) comprises a primary side and a secondary side, the primary side is electrically connected with the control module (110) and a power supply, and the secondary side is electrically connected with the feedback module (130) and the plurality of output modules (140); wherein, The plurality of output modules (140) are used for outputting different voltages. The feedback module (130) comprises an RC compensation network (131), the gain margin of the RC compensation network (131) is greater than 10 dB, and the phase margin is greater than 45 degrees.

2. The switching power supply circuit according to claim 1, characterized by The RC compensation network (131) comprises a compensation resistor (R6) and a compensation capacitor (C1), and the compensation resistor (R6) is connected with the compensation capacitor (C1). The resistance value of the compensation resistor (R6) is 45KΩ-55KΩ, and the capacitance value of the compensation capacitor (C1) is 0.045μF-0.05μF.

3. The switching power supply circuit according to claim 2, characterized in that, The resistance value of the compensation resistor (R6) is 51KΩ, and the capacitance value of the compensation capacitor (C1) is 0.047μF.

4. The switching power supply circuit according to claim 1, characterized by The secondary side comprises different output windings, the output modules (140) are connected with different output windings, and the switching power supply circuit further comprises an output maintaining module, and the output maintaining module is connected between output windings with different voltage amplitudes.

5. The switching power supply circuit according to claim 4, characterized in that, The output windings comprise a 12V output winding and a 6V output winding, and the output maintaining module is connected in series between the 12V output winding and the 6V output winding.

6. The switching power supply circuit according to claim 5, characterized in that, The output module (140) connected with the 6V output winding comprises a low dropout regulator, an input end of the low dropout regulator is connected with the 6V output winding, and an output end of the low dropout regulator is used for connecting a load; and the low dropout regulator is used for stabilizing the input end voltage to 3.3V and outputting.

7. The switching power supply circuit according to claim 4, characterized by The output maintaining module comprises a resistor or a zener diode. When the output maintaining module comprises a resistor, one end of the resistor is connected with an output winding with a high voltage amplitude, and the other end is connected with an output winding with a low voltage amplitude. When the output maintaining module comprises a zener diode, a cathode of the zener diode is connected with an output winding with a high voltage amplitude, and an anode of the zener diode is connected with an output winding with a low voltage amplitude.

8. The switching power supply circuit according to claim 1, characterized by The feedback module (130) further comprises an adjustable precision voltage stabilizer (132), an optical coupler (IC2), a voltage dividing component and a current limiting component (R5), the optical coupler (IC2) comprises a light emitting diode and a light receiving triode, the light receiving triode is connected with the control module (110), one end of the current limiting component (R5) is connected with the secondary side and the anode of the light emitting diode, the other end of the current limiting component (R5) is connected with the cathode of the light emitting diode and the cathode of the adjustable precision voltage stabilizer (132) respectively, the anode of the adjustable precision voltage stabilizer is grounded, the first end of the voltage dividing component is connected with the secondary side, the second end of the voltage dividing component is connected with one end of the RC compensation network (131) and the reference electrode of the adjustable precision voltage stabilizer (132), the other end of the RC compensation network (131) is connected with the cathode of the adjustable precision voltage stabilizer (132), and the third end of the voltage dividing component is grounded.

9. The switching power supply circuit according to claim 8, characterized in that, The voltage dividing component comprises a first resistor (R1), a second resistor (R2) and a third resistor (R3), the feedback module (130) further comprises a fourth resistor (R4), one end of the current limiting component (R5) is connected with the secondary side through the fourth resistor (R4), one end of the first resistor (R1), the second resistor (R2) and the third resistor (R3) in series is the first end, the other end is the third end, and the second end is between the second resistor (R2) and the third resistor (R3).

10. An electronic device, comprising: The electronic device comprises a load and the switching power supply circuit according to any one of claims 1 to 9, the load is connected with the output module (140) of the switching power supply circuit and is powered by the switching power supply circuit.

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