Hybrid frequency modulation and width modulation mode integrated switching power supply

Abstract

The application belongs to the technical field of switching power supply, and provides a hybrid frequency modulation and width modulation mode integrated switching power supply, which comprises a primary rectification filter circuit arranged at the primary side of a transformer T1 and a secondary rectification filter circuit arranged at the secondary side of the transformer T1, further comprises an intelligent hybrid frequency modulation and width modulation circuit connected to the primary rectification filter circuit and a secondary sampling feedback circuit connected to the secondary rectification filter circuit, and the intelligent hybrid frequency modulation and width modulation circuit and the secondary sampling feedback circuit are connected through an optical coupler PC1. The power supply can realize the hybrid adjustment mode of the intelligent PWM and PFM of the switching power supply, can adopt the hybrid frequency modulation and width modulation mode by combining the advantages and disadvantages of the PWM and PFM, can make the power supply work in different modulation modes according to the load change, and can optimize the efficiency of the power supply in the full load range and improve the performance of the power supply.

Description

Technical Field

[0001] This utility model belongs to the field of switching power supply technology, and in particular relates to an integrated switching power supply with hybrid frequency modulation and pulse width modulation modes. Background Technology

[0002] With the widespread application of switching power supply products, market demand is increasing, and the development of switching power supplies in the emerging electronic field is rapid. Power supply products are constantly being updated and iterated to meet the ever-changing market demands; in the past two years, the power supply update cycle has changed from once every two years to once a year, with smaller, more efficient, and energy-saving products constantly emerging.

[0003] Switching power supplies undergoing iteration require more innovative functions to meet market demands. Intelligent integration has always been a trend, and the key to improving output stability and efficiency lies in how to intelligently adjust operating states according to changes in power load, maintain optimal performance, and operate reliably in complex industrial electronic environments. Utility Model Content

[0004] To address the aforementioned technical problems, this application proposes a hybrid frequency modulation and pulse width modulation integrated switching power supply, the specific technical solution of which is as follows:

[0005] A hybrid frequency modulation and pulse width modulation (PWM) integrated switching power supply includes a primary rectifier and filter circuit disposed on the primary side of transformer T1 and a secondary rectifier and filter circuit disposed on the secondary side of transformer T1. It also includes an intelligent hybrid frequency modulation and pulse width modulation circuit connected to the primary rectifier and filter circuit and a secondary sampling feedback circuit connected to the secondary rectifier and filter circuit. The intelligent hybrid frequency modulation and pulse width modulation circuit and the secondary sampling feedback circuit are connected through an optocoupler PC1.

[0006] In the intelligent hybrid frequency modulation and width modulation circuit, pin 1 of the current mode controller U2 is grounded, pin 2 is connected to the power supply, pin 3 is connected to pin 4 of the optocoupler PC1, pin 3 of the optocoupler PC1 is grounded, capacitor C9 is connected in parallel between pins 3 and 4 of the optocoupler PC1, pin 4 of the current mode controller U2 is connected to ground through resistors R6, R7 and R8 connected in parallel, and pins 5, 6, 7 and 8 of the current mode controller U2 are the drains of the integrated MOSFET and are connected to transformer T1;

[0007] In the secondary sampling feedback circuit, pin 1 of optocoupler PC1 is connected to one end of resistor R23, pin 2 of optocoupler PC1 is connected to the other end of resistor R23, one end of resistor R23 is connected to one end of resistor R12, the other end of resistor R12 is connected to the positive terminal of Zener diode DZ3, the negative terminal of Zener diode DZ3 is connected to V+, the other end of resistor R23 is connected to pin 3 of voltage regulator IC2, pin 2 of voltage regulator IC2 is connected to SGND, one end of capacitor C18 is connected to pin 3 of voltage regulator IC2, and capacitor C... The other end of resistor 18 is connected to SGND. One end of resistor R24 ​​is connected to pin 3 of voltage regulator IC2. The other end of resistor R24 ​​is connected to one end of capacitor C20. The other end of capacitor C20 is connected to pin 2 of voltage regulator IC2. Pin 1 of voltage regulator IC2 is connected to one end of resistor R22. The other end of resistor R22 is connected to V+. Pin 1 of voltage regulator IC2 is connected to one end of resistor R25. The other end of resistor R25 is connected to one end of potentiometer VR1. The other end of potentiometer VR1 is connected to SGND.

[0008] Optionally, the current-mode controller U2 is selected as ME8132.

[0009] Optionally, in the primary rectifier and filter circuit, pin 1 of terminal CN1 is connected to one end of fuse FS1, pin 2 of terminal CN1 is connected to one end of thermistor RT1, pin 3 of terminal CN1 is grounded, the other end of fuse FS1 is connected to one end of varistor RV1, the other end of thermistor RT1 is connected to the other end of varistor RV1, capacitor CX1 is connected in parallel across varistor RV1, the two ends of capacitor CX1 are connected in parallel across inductor L1, the other two ends of inductor L1 are connected in parallel across resistors R42 and R41 connected in series, resistors R1 and R2 are connected in series and then in parallel across resistors R41 and R42 connected in series, one end of resistor R1 is connected to the AC terminal of bridge rectifier BD1, one end of resistor R2 is connected to the other AC terminal of bridge rectifier BD1, and capacitor C3 is connected between ground and V- terminal of bridge rectifier BD1.

[0010] Optionally, in the switching circuit, the V+ terminal of bridge rectifier BD1 is connected to the positive terminal of capacitor C1, and the V- terminal of bridge rectifier BD1 is connected to the negative terminal of capacitor C1. Simultaneously, the negative terminal of capacitor C1 is connected to GND. Capacitor C7 is connected to the positive terminal of capacitor C1, and the other end of capacitor C7 is connected to the negative terminal of diode D1. Resistors R3 and R3A are connected in parallel and then in parallel with capacitor C7. One end of capacitor C7 is connected to pin 1 of converter T1, and the positive terminal of diode D1 is connected to pin 4 of converter T1. The positive terminal of pin 1 is connected to the DRAIN terminal of the current mode controller U2. Pin 5 of converter T1 is connected to the positive terminal of diode D3. Pin 6 of converter T1 is connected to GND. The negative terminal of diode D3 is connected to the positive terminal of capacitor C8. The negative terminal of capacitor C8 is connected to GND. Capacitor C2 is connected in parallel across capacitor C8. The positive terminal of capacitor C1 is connected to one end of resistor R4. The other end of resistor R4 is connected to one end of resistor R5. The other end of resistor R5 is connected to the positive terminal of capacitor C8. The positive terminal of capacitor C8 is VDD.

[0011] Optionally, in the secondary rectifier and filter circuit, pin 10 of converter T1 is connected to the positive terminal of diode D4. Resistor R36 and capacitor C13 are connected in series across the two ends of diode D4. The negative terminal of diode D4 is connected to the positive terminal of capacitor C14. Pin 7 of converter T1 is connected to SGND. The positive terminal of capacitor C14 is connected to one end of inductor L2. The other end of inductor L2 is connected to the positive terminal of capacitor C15. The negative terminal of capacitor C15 is connected to SGND. Resistor R16 and resistor R15 are connected in parallel across capacitor C15. One end of capacitor C21 is connected to SGND. The other end of capacitor C21 is connected to ground. One end of resistor R27 is connected to the output V+. The other end of resistor R27 is connected to the positive terminal of the LED. The negative terminal of the LED is connected to SGND.

[0012] The beneficial effects of this utility model are as follows:

[0013] The power supply disclosed in this application can achieve a hybrid adjustment mode of intelligent PWM and PFM for switching power supplies. Combining the advantages and disadvantages of PWM and PFM, a hybrid frequency modulation and pulse width modulation mode can be adopted, allowing the power supply to operate in different modulation modes according to load changes. When the power supply load is extremely low or in standby mode, the power supply modulation mode enters BURST MODE. When the power supply load enters a low-load state, the power supply modulation mode enters DPWM mode, reducing the total switching loss by reducing one switching action in each switching cycle. When the power supply load enters a moderate half-load state, the power supply modulation mode enters PFM mode, with a constant duty cycle and varying switching frequency. When the power supply load enters a heavy-load state, the power supply modulation mode enters PWM mode, with a varying duty cycle and constant switching frequency, thereby optimizing the efficiency of the power supply across the entire load range and improving the power supply performance. Attached Figure Description

[0014] Figure 1 The diagram shown is of an integrated switching power supply with intelligent hybrid frequency modulation and pulse width modulation mode.

[0015] Figure 2 The diagram shown is a power curve control graph of a current-mode controller;

[0016] Figure 3 The waveforms shown are for PWM mode and PFM mode. Detailed Implementation

[0017] In the following description, certain specific details are set forth to provide a thorough understanding of various embodiments. However, those skilled in the art will understand that the present invention can be practiced without these details. In other instances, well-known structures have not been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments. Unless the context otherwise requires, throughout the specification and appended claims, the word "comprising" shall be interpreted in an open-ended, inclusive sense, i.e., as "including but not limited to".

[0018] Figure 1 The diagram shown is a schematic of an integrated switching power supply with intelligent hybrid frequency modulation and pulse width modulation mode. Based on the diagram, it can be seen that the switching power supply in this application includes a primary rectifier and filter circuit, a switching conversion circuit, a secondary rectifier and filter circuit, a secondary sampling feedback circuit, and an intelligent hybrid frequency modulation and pulse width modulation circuit.

[0019] In the intelligent hybrid frequency modulation and width modulation circuit, pin 1 of the current-mode controller U2 is grounded, pin 2 is connected to the power supply, pin 3 is connected to pin 4 of the optocoupler PC1, pin 3 of the optocoupler PC1 is grounded, capacitor C9 is connected in parallel between pins 3 and 4 of the optocoupler PC1, and pin 4 of the current-mode controller U2 is connected to ground through resistors R6, R7, and R8 connected in parallel. Pins 5, 6, 7, and 8 are the drains of the integrated MOSFET and are connected to the switching transformer.

[0020] The current-mode controller U2 uses the ME8132, which is required for the intelligent hybrid frequency modulation and pulse width modulation circuit. The ME8132 requires VDD power to function properly. Resistors R6, R7, and R8 are sampling resistors that sample the internal MOSFET current Ipeak to obtain the Vcs voltage. This Vcs voltage is crucial for controlling the entry into different modulation modes; different PWM and PFM modes are determined by this voltage. Adjusting the values ​​of resistors R6, R7, and R8 changes Vcs, thus controlling the entry into different modulation modes under different load conditions. Simultaneously, changes in the voltage received from the secondary feedback at the FB pin also determine the entry and exit control states for PWM and PFM modulation modes.

[0021] The ME8132 is a high-performance current-mode controller with an integrated 650V power MOSFET. Its power control mode consists of a hybrid modulation scheme, where pulse-width modulation (PWM) and frequency modulation are achieved by varying Ipeak (MOSFET peak current) and fs with the feedforward (FB) feedback. Figure 2 The power curve control diagram of ME8132 is shown.

[0022] Combination Figure 2 When the power supply load is extremely low or in standby mode, the power supply modulation state enters BURST MODE. During several switching cycles, the output voltage gradually increases. When the output voltage reaches a certain value, the system stops working, and this shutdown period is relatively long. After the system stops working, the output voltage gradually decreases until it drops to a certain value, at which point the system starts working again. This cycle repeats. This operating mode is called Burst mode. In this mode, the FB voltage does not exceed 0.8V, the switching frequency is 25kHz, and the Ipeak (Vcs) voltage is 0.2V.

[0023] When the power supply load enters a low-load condition, the power supply modulation mode enters DPWM mode (Discontinuous Pulse Width Modulation), which reduces the total switching loss by reducing one switching action in each switching cycle. At this time, the switching frequency is still 25kHz, the voltage of Vcs changes from 0.2V to 0.5V, and the voltage of FB also changes accordingly from 0.8V to 1.7V.

[0024] When the power supply load enters a moderate half-load condition, the power supply modulation mode enters PFM (Pulse Frequency Modulation) mode. Its duty cycle remains unchanged and Ipeak is fixed, while the switching frequency changes. Ipeak remains unchanged, meaning the voltage of Vcs remains unchanged at 0.5V. The switching frequency changes from 25kHz to 75kHz, and the voltage of FB changes from 1.7V to 2.2V.

[0025] When the power supply load becomes heavy, it switches to PWM (Pulse Width Modulation) mode, where the duty cycle changes but the switching frequency remains constant at 75kHz. The VCS voltage changes from 0.5V to 0.8V, and the FB voltage changes from 2.2V to 3.1V, operating within the corresponding range based on different power curves. Compared to single PWM or single PFM, efficiency is optimized across the entire load range, resulting in improved power supply performance.

[0026] Under no-load or light-load conditions, most of the energy loss occurs in the power switching transistors, and this loss is directly proportional to the switching frequency. Therefore, a lower switching frequency can effectively reduce the loss.

[0027] Figure 3 The diagram shows waveforms for PWM and PFM modes. Specifically, PWM (pulse width modulation) is a switching regulator circuit that adjusts its duty cycle through voltage feedback while keeping the output frequency constant, thus stabilizing the output voltage. PFM (pulse frequency modulation) is a switching regulator circuit where the frequency of the modulating signal changes with the amplitude of the input signal, while its duty cycle remains constant. Since the modulating signal is usually a square wave signal with varying frequency, PFM is also called square wave FM. Its characteristic is that the switching frequency, or the switching period, varies. PWM involves varying the width of the frequency, while PFM involves varying the presence or absence of the frequency. PWM controls the output using the pulse width, while PFM controls the output using the presence or absence of the pulse.

[0028] PWM (Pulse Width Modulation) offers high efficiency under full load and can operate in continuous conduction mode, resulting in stable and low output ripple. Compared to PWM, PFM (Pulse-Conduction Mode) has lower output current, but because the PFM converter stops operating once the set voltage is reached, its current consumption is significantly reduced. This reduced current consumption improves efficiency under low load. However, the output ripple deteriorates, and stability is not as good as PWM. Combining the advantages and disadvantages of PWM and PFM, a hybrid frequency modulation and pulse-width modulation (PWM) mode can be adopted. This allows the power supply to operate in different modulation modes according to load changes, perfectly balancing output stability and efficiency.

[0029] In the primary rectifier and filter circuit, pin 1 of terminal CN1 is connected to one end of fuse FS1, pin 2 of terminal CN1 is connected to one end of thermistor RT1, pin 3 of terminal CN1 is grounded, the other end of fuse FS1 is connected to one end of varistor RV1, the other end of thermistor RT1 is connected to the other end of varistor RV1, capacitor CX1 is connected in parallel across varistor RV1, the two ends of capacitor CX1 are connected in parallel across inductor L1, the other two ends of inductor L1 are connected in parallel across resistors R42 and R41 connected in series, resistors R1 and R2 are connected in series and then in parallel across resistors R41 and R42 connected in series, one end of resistor R1 is connected to the AC terminal of bridge rectifier BD1, one end of resistor R2 is connected to the other AC terminal of bridge rectifier BD1, and capacitor C3 is connected between ground and V- terminal of bridge rectifier BD1.

[0030] In the switching circuit, the V+ terminal of bridge rectifier BD1 is connected to the positive terminal of capacitor C1, and the V- terminal of bridge rectifier BD1 is connected to the negative terminal of capacitor C1. Simultaneously, the negative terminal of capacitor C1 is connected to GND. Capacitor C7 is connected to the positive terminal of capacitor C1, and the other end of capacitor C7 is connected to the negative terminal of diode D1. Resistors R3 and R3A are connected in parallel and then in parallel with capacitor C7. One end of capacitor C7 is connected to pin 1 of converter T1. The positive terminal of diode D1 is connected to pin 4 of converter T1. The positive terminal of diode D1 is connected to the DRAIN terminal of current mode controller U2. Pin 5 of converter T1 is connected to the positive terminal of diode D3. Pin 6 of converter T1 is connected to GND. The negative terminal of diode D3 is connected to the positive terminal of capacitor C8, and the negative terminal of capacitor C8 is connected to GND. Capacitor C2 is connected in parallel across capacitor C8. The positive terminal of capacitor C1 is connected to one end of resistor R4. The other end of resistor R4 is connected to one end of resistor R5. The other end of resistor R5 is connected to the positive terminal of capacitor C8. The positive terminal of capacitor C8 is VDD.

[0031] In the secondary rectifier and filter circuit, pin 10 of converter T1 is connected to the anode of diode D4. Resistor R36 and capacitor C13 are connected in series across diode D4. The cathode of diode D4 is connected to the anode of capacitor C14. Pin 7 of converter T1 is connected to SGND. The anode of capacitor C14 is connected to one end of inductor L2, and the other end of inductor L2 is connected to the anode of capacitor C15. The cathode of capacitor C15 is connected to SGND. Resistors R16 and R15 are connected in parallel across capacitor C15. One end of capacitor C21 is connected to SGND, and the other end of capacitor C21 is connected to ground. One end of resistor R27 is connected to the output V+, and the other end of resistor R27 is connected to the anode of the LED. The cathode of the LED is connected to SGND.

[0032] In the secondary sampling feedback circuit, pin 1 of optocoupler PC1 is connected to one end of resistor R23, pin 2 of optocoupler PC1 is connected to the other end of resistor R23, one end of resistor R23 is connected to one end of resistor R12, the other end of resistor R12 is connected to the positive terminal of Zener diode DZ3, the negative terminal of Zener diode DZ3 is connected to V+, the other end of resistor R23 is connected to pin 3 of voltage regulator IC2, pin 2 of voltage regulator IC2 is connected to SGND, one end of capacitor C18 is connected to pin 3 of voltage regulator IC2, and capacitor C1... The other end of resistor 8 is connected to SGND. One end of resistor R24 ​​is connected to pin 3 of voltage regulator IC2. The other end of resistor R24 ​​is connected to one end of capacitor C20. The other end of capacitor C20 is connected to pin 2 of voltage regulator IC2. Pin 1 of voltage regulator IC2 is connected to one end of resistor R22. The other end of resistor R22 is connected to V+. Pin 1 of voltage regulator IC2 is connected to one end of resistor R25. The other end of resistor R25 is connected to one end of potentiometer VR1. The other end of potentiometer VR1 is connected to SGND.

[0033] The above embodiments are only used to illustrate the technical solution of this utility model, and are not intended to limit it.

Claims

1. A hybrid frequency modulation and pulse width modulation integrated switching power supply, comprising a primary rectifier and filter circuit disposed on the primary side of transformer T1 and a secondary rectifier and filter circuit disposed on the secondary side of transformer T1, characterized in that, It also includes an intelligent hybrid frequency modulation and pulse width modulation circuit connected to the primary rectifier and filter circuit and a secondary sampling feedback circuit connected to the secondary rectifier and filter circuit. The intelligent hybrid frequency modulation and pulse width modulation circuit and the secondary sampling feedback circuit are connected through an optocoupler PC1. In the intelligent hybrid frequency modulation and width modulation circuit, pin 1 of the current mode controller U2 is grounded, pin 2 is connected to the power supply, pin 3 is connected to pin 4 of the optocoupler PC1, pin 3 of the optocoupler PC1 is grounded, capacitor C9 is connected in parallel between pins 3 and 4 of the optocoupler PC1, pin 4 of the current mode controller U2 is connected to ground through resistors R6, R7 and R8 connected in parallel, and pins 5, 6, 7 and 8 of the current mode controller U2 are the drains of the integrated MOSFET and are connected to transformer T1; In the secondary sampling feedback circuit, pin 1 of optocoupler PC1 is connected to one end of resistor R23, pin 2 of optocoupler PC1 is connected to the other end of resistor R23, one end of resistor R23 is connected to one end of resistor R12, the other end of resistor R12 is connected to the positive terminal of Zener diode DZ3, the negative terminal of Zener diode DZ3 is connected to V+, the other end of resistor R23 is connected to pin 3 of voltage regulator IC2, pin 2 of voltage regulator IC2 is connected to SGND, one end of capacitor C18 is connected to pin 3 of voltage regulator IC2, and capacitor C... The other end of resistor 18 is connected to SGND. One end of resistor R24 ​​is connected to pin 3 of voltage regulator IC2. The other end of resistor R24 ​​is connected to one end of capacitor C20. The other end of capacitor C20 is connected to pin 2 of voltage regulator IC2. Pin 1 of voltage regulator IC2 is connected to one end of resistor R22. The other end of resistor R22 is connected to V+. Pin 1 of voltage regulator IC2 is connected to one end of resistor R25. The other end of resistor R25 is connected to one end of potentiometer VR1. The other end of potentiometer VR1 is connected to SGND.

2. The hybrid frequency modulation and pulse width modulation mode integrated switching power supply according to claim 1, characterized in that, The current-mode controller U2 is an ME8132.

3. The integrated switching power supply with hybrid frequency modulation and pulse width modulation mode according to claim 1, characterized in that, In the primary rectifier and filter circuit, pin 1 of terminal CN1 is connected to one end of fuse FS1, pin 2 of terminal CN1 is connected to one end of thermistor RT1, pin 3 of terminal CN1 is grounded, the other end of fuse FS1 is connected to one end of varistor RV1, the other end of thermistor RT1 is connected to the other end of varistor RV1, capacitor CX1 is connected in parallel across varistor RV1, the two ends of capacitor CX1 are connected in parallel across inductor L1, the other two ends of inductor L1 are connected in parallel across resistors R42 and R41 connected in series, resistors R1 and R2 are connected in series and then in parallel across resistors R41 and R42 connected in series, one end of resistor R1 is connected to the AC terminal of bridge rectifier BD1, one end of resistor R2 is connected to the other AC terminal of bridge rectifier BD1, and capacitor C3 is connected between ground and V- terminal of bridge rectifier BD1.

4. The hybrid frequency modulation and pulse width modulation mode integrated switching power supply according to claim 1, characterized in that, It also includes a switching circuit. In this switching circuit, the V+ terminal of bridge rectifier BD1 is connected to the positive terminal of capacitor C1, and the V- terminal of bridge rectifier BD1 is connected to the negative terminal of capacitor C1. Simultaneously, the negative terminal of capacitor C1 is connected to GND. Capacitor C7 is connected to the positive terminal of capacitor C1, and the other end of capacitor C7 is connected to the negative terminal of diode D1. Resistors R3 and R3A are connected in parallel and then in parallel with capacitor C7. One end of capacitor C7 is connected to pin 1 of converter T1, and the positive terminal of diode D1 is connected to pin 4 of converter T1. The positive terminal of diode D1 is connected to the DRAIN terminal of current mode controller U2. Pin 5 of converter T1 is connected to the positive terminal of diode D3. Pin 6 of converter T1 is connected to GND. The negative terminal of diode D3 is connected to the positive terminal of capacitor C8. The negative terminal of capacitor C8 is connected to GND. Capacitor C2 is connected in parallel across capacitor C8. The positive terminal of capacitor C1 is connected to one end of resistor R4. The other end of resistor R4 is connected to one end of resistor R5. The other end of resistor R5 is connected to the positive terminal of capacitor C8. The positive terminal of capacitor C8 is VDD.

5. The integrated switching power supply with hybrid frequency modulation and pulse width modulation mode according to claim 1, characterized in that, In the secondary rectifier and filter circuit, pin 10 of converter T1 is connected to the positive terminal of diode D4. Resistor R36 and capacitor C13 are connected in series across diode D4. The negative terminal of diode D4 is connected to the positive terminal of capacitor C14. Pin 7 of converter T1 is connected to SGND. The positive terminal of capacitor C14 is connected to one end of inductor L2. The other end of inductor L2 is connected to the positive terminal of capacitor C15. The negative terminal of capacitor C15 is connected to SGND. Resistor R16 and resistor R15 are connected in parallel across capacitor C15. One end of capacitor C21 is connected to SGND, and the other end of capacitor C21 is connected to ground. One end of resistor R27 is connected to the output V+, and the other end of resistor R27 is connected to the positive terminal of the LED. The negative terminal of the LED is connected to SGND.

Images