Interleaved buck-boost positive and negative switch power supply topology circuit

Abstract

The application discloses an interlaced BUCK-BOOST positive and negative switching power supply topology circuit and belongs to the technical field of switching power supplies. The topology circuit comprises an energy storage inductor L, a switching circuit comprising switches K1, K2 and K3, a rectification filtering circuit comprising a positive power output rectification diode D2, a positive power filtering capacitor C2, a negative power output rectification diode D1 and a negative power filtering capacitor C1, and a control circuit configured to perform interlaced timing control, wherein the interlaced timing control comprises alternately performed first and second charge and discharge periods. The application solves the problems of high cost and large occupied area caused by the need of two inductors for realizing positive and negative power output in the prior art, and has the advantages of low cost, high integration and wide applicability.

Description

Technical Field

[0001] This invention belongs to the field of switching power supply technology, specifically relating to an interleaved BUCK-BOOST positive and negative switching power supply topology circuit. Background Technology

[0002] Switching power supplies are an indispensable part of electronic circuits, supplying power to digital and analog circuits. They use switching transistors instead of Zener transistors and store energy through inductors to achieve voltage conversion, offering significant advantages such as high efficiency and low heat generation. A typical power supply consists of a control circuit, switching transistors, inductors or transformers, and other electrical components.

[0003] In non-isolated switching power supplies, typically one energy storage inductor is needed for each power supply. When both positive and negative power are required simultaneously, a BUCK circuit using one inductor is needed for the positive power, and a BUCK-BOOST circuit using one inductor is needed for the negative power. Therefore, to achieve simultaneous output of positive and negative power, two inductors are needed respectively. However, inductors in circuits are often very expensive and take up board space.

[0004] Considering cost factors and integration, using one inductor per power supply may not meet the requirements in subsequent circuit designs; therefore, there is an urgent need for a topology circuit that can achieve simultaneous output of positive and negative voltages using only one inductor. Summary of the Invention

[0005] The present invention aims to provide an interleaved BUCK-BOOST positive and negative switching power supply topology to solve the problem that the existing technology requires two independent inductors to realize positive and negative power output, resulting in high cost and large footprint.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an interleaved BUCK-BOOST positive and negative switching power supply topology circuit, the topology circuit comprising: One energy storage inductor L; The switching circuit includes switches K1, K2, and K3; The rectifier and filter circuit includes a positive power supply output rectifier diode D2, a positive power supply filter capacitor C2, a negative power supply output rectifier diode D1, and a negative power supply filter capacitor C1; and A control circuit configured to perform interleaved timing control, the interleaved timing control including alternating first charge-discharge cycles and second charge-discharge cycles; During the first charge and discharge cycle, the control circuit controls the switches K1 and K2 to be turned on and the switch K3 to be turned off, so that the input power supply U charges the inductor L; after charging is completed, the control circuit controls the switches K1 and K2 to be turned off and the switch K3 to be turned on, so that the inductor L discharges to the positive power supply filter capacitor C2 through the positive power supply output rectifier diode D2 to output a positive voltage. During the second charge / discharge cycle, the control circuit controls switches K1 and K2 to be turned on and switch K3 to be turned off, so that the input power supply U charges the inductor L; after charging is completed, the control circuit controls switches K1 and K3 to be turned off and switch K2 to be turned on, so that the inductor L discharges to the negative power supply filter capacitor C1 through the negative power supply output rectifier diode D1 to output a negative voltage.

[0007] Preferably, the control circuit uses only one inductor L to realize a positive voltage to positive and negative voltage regulated switching power supply.

[0008] Preferably, the control circuit controls the current of inductor L in each charge and discharge cycle, and under unbalanced load, it needs to operate in discontinuous conduction mode (DCM).

[0009] Preferably, the topology circuit further includes a feedback loop and an error amplifier, used to adjust the charging time of inductor L in the first charge-discharge cycle and / or the second charge-discharge cycle according to the output value of the positive voltage and / or negative voltage, so as to achieve regulated output.

[0010] Preferably, the switches K1, K2, and K3 are transistor switches.

[0011] In another aspect, the present invention also provides a control method for a base-interleaved BUCK-BOOST positive and negative switching power supply topology circuit, comprising the following steps: a. In the first charge / discharge cycle, control switches K1 and K2 are turned on to charge inductor L; b. After the first charge-discharge cycle ends, control switches K1 and K2 are turned off, and control switch K3 is turned on, so that inductor L discharges through positive power output rectifier diode D2 to positive power filter capacitor C2 to generate positive power output; c. In the second charge / discharge cycle, control switches K1 and K2 are turned on to recharge inductor L; d. To end the second charge / discharge cycle, control switches K1 and K3 are turned off, and control switch K2 is turned on, so that inductor L discharges through negative power supply output rectifier diode D1 to negative power supply filter capacitor C1 to generate negative power supply output. e. Repeat steps a to d above to achieve continuous output of positive and negative power supplies.

[0012] Compared with the prior art, the beneficial effects of the present invention are: The interleaved BUCK-BOOST positive and negative switching power supply topology provided by this invention, through ingenious circuit structure design and unique interleaved timing control, can simultaneously generate stable positive and negative voltage outputs using only one energy storage inductor. This significantly reduces the material cost and PCB footprint of the power supply system, making it particularly suitable for applications requiring dual positive and negative power supplies but sensitive to space and cost, such as operational amplifiers and power device driver circuits. Furthermore, this topology also possesses the buck-boost characteristics of a BUCK-BOOST circuit, enabling it to adapt to a wider input voltage range. Attached Figure Description

[0013] Figure 1 The circuit diagram for the inductor charging stage in the interleaved BUCK-BOOST positive and negative switching power supply topology provided in the embodiment of the present invention.

[0014] Figure 2 The circuit diagram of the interleaved BUCK-BOOST positive and negative switching power supply topology provided in the embodiment of the present invention is shown in the positive power supply discharge phase of the first charge and discharge cycle.

[0015] Figure 3 The circuit diagram of the interleaved BUCK-BOOST positive and negative switching power supply topology provided in the embodiment of the present invention is shown in the negative power supply discharge stage of the second charge and discharge cycle.

[0016] Figure 4 The inductor current charging and discharging timing diagram of the interleaved BUCK-BOOST positive and negative switching power supply topology provided in the embodiment of the present invention in discontinuous conduction mode.

[0017] Figure 5 The overall operating timing and voltage waveform diagram of the interleaved BUCK-BOOST positive and negative switching power supply topology provided in the embodiments of the present invention.

[0018] Figure 6 The inductor current charging and discharging timing diagram of the interleaved BUCK-BOOST positive and negative switching power supply topology provided in the embodiment of the present invention in continuous conduction mode. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] Figures 1 to 6 Explanation of Chinese symbols: U: Input power supply; L: Inductor; K1: First switch; K2: Second switch; K3: Third switch; D1: Negative power supply output rectifier diode; D2: Positive power supply output rectifier diode; C1: Negative power supply filter capacitor; C2: Positive power supply filter capacitor.

[0021] Reference Appendix Figure 1 The initial current of inductor L is 0.

[0022] I. During the first charge / discharge cycle (positive power supply output cycle): Positive power supply charging phase (time period t1): such as Figure 1 As shown, switches K1 and K2 are open, and K3 is open, forming a circuit with the input power supply U: U positive terminal -> K1 -> L -> K2 -> U negative terminal. At this time, the input power supply U charges the inductor L. After time t1, switches K1 and K2 are simultaneously opened. At this point, the current in inductor L flows downwards, and the magnitude of the current is: Then, the positive power supply discharge phase begins (time period t2): as follows Figure 2 As shown, with switches K1 and K2 closed and K3 open, the downward current direction of inductor L remains unchanged, continuing downwards. The current flows from ground through switch K3, through inductor L, and through diode D2, charging the output positive power supply capacitor C2 to form the positive output power supply. At this time, the output positive power supply voltage is U1, and the time it takes for the inductor current to drop to 0 is: After time t3 (after the current in inductor L drops to 0, the circuit will remain in an idle state until the end of the first charge / discharge cycle, in preparation for the next cycle), the second charge / discharge cycle will begin.

[0023] II. During the second charge / discharge cycle (negative power supply output cycle): Charging phase (t4 time period): as attached Figure 1 As shown, switches K1 and K2 are open, and K3 is open. The input power supply U charges the inductor L. After time t4, switches K1 and K2 are simultaneously opened. At this time, the current in inductor L flows downwards, and the magnitude of the current is: Negative power supply discharge phase (time period t5): as attached Figure 3 As shown, with switch K1 closed, K2 open, and K3 closed, the downward current direction of inductor L remains unchanged. The current flows from the negative power supply output capacitor C1, through diode D1, through inductor L, through switch K2, and to ground, forming a negative output power supply. At this time, the output negative power supply voltage is U2, and the time it takes for the current in inductor L to drop to 0 is: After time t6 (after the current in inductor L drops to 0, the circuit will remain idle until the end of the second charge / discharge cycle), the first charge / discharge cycle will begin again, and this cycle will repeat.

[0024] Since the current in inductor L is reduced to 0 at the end of the first and second charge-discharge cycles, the current magnitudes of the first and second charge-discharge cycles do not affect each other.

[0025] As attached Figure 4 As shown, assuming the first and second charge / discharge cycles use the same period T, then: The combined cycle of the first and second charge-discharge cycles is 2T. The overall operating timing sequence is shown in the attached figure. Figure 5 As shown.

[0026] The input power for the first charge / discharge cycle is: Assuming the voltage drop of the rectifier diode is negligible, and the current of the inductor L discharges to 0 in the first cycle, the output power of the positive power supply is equal to P1. Adjusting the power of the positive power supply only requires adjusting the time t1.

[0027] The input power for the second charge / discharge cycle is: Assuming the voltage drop of the rectifier diode is negligible, and the current of the inductor L discharges to 0 in the second cycle, the output power of the negative power supply is equal to P2. Adjusting the power of the positive power supply only requires adjusting the time t4.

[0028] The total input power is the sum of P1 and P2.

[0029] If the inductor current does not discharge to 0 at the end of the first charge / discharge cycle, it is I3, as shown in the attached figure. Figure 6 As shown, the final current charging inductor L during the second charge / discharge cycle is: Even if the charging time t4 of inductor L is 0, the energy present in inductor L is at least: The minimum power required for a negative power source is: At this moment, the power output of the positive power supply is: The situation persists when switching from the second charge / discharge cycle to the first. Therefore, when the load is unknown, a discontinuous design should be used as much as possible.

[0030] When using a discontinuous design, the input voltage is U, the positive output is Up with power Pp, the negative output is Un with power Pn, the period is T, and the inductor L is calculated as follows: First, calculate based on the first charge / discharge cycle. Assuming that the inductor L is completely discharged during the first charge / discharge cycle, we have: Based on power: Substituting, we get: Calculations show that L can only take the following maximum values: Similarly, using the second charge / discharge cycle for calculation, the maximum value of L can only be: To ensure that the first and second charge / discharge cycles operate in an intermittent state simultaneously, L must be the minimum of Ln and Lp.

[0031] Because the charging cycle for a single load capacitor is 2T, the output voltage ripple is related to both the load capacitor and the load current. The peak-to-peak value of the ripple is: The interleaved BUCK-BOOST positive and negative switching power supply topology provided by this invention, through ingenious circuit structure design and unique interleaved timing control, can simultaneously generate stable positive and negative voltage outputs using only one energy storage inductor. This significantly reduces the material cost and PCB footprint of the power supply system, making it particularly suitable for applications requiring dual positive and negative power supplies but sensitive to space and cost, such as operational amplifiers and power device driver circuits. Furthermore, this topology also possesses the buck-boost characteristics of a BUCK-BOOST circuit, enabling it to adapt to a wider input voltage range.

[0032] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0033] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. An interleaved BUCK-BOOST positive and negative switching power supply topology circuit, characterized in that, The topology circuit includes: One energy storage inductor L; The switching circuit includes switches K1, K2, and K3; The rectifier and filter circuit includes a positive power supply output rectifier diode D2, a positive power supply filter capacitor C2, a negative power supply output rectifier diode D1, and a negative power supply filter capacitor C1; and A control circuit configured to perform interleaved timing control, the interleaved timing control including alternating first charge-discharge cycles and second charge-discharge cycles; During the first charge and discharge cycle, the control circuit controls the switches K1 and K2 to be turned on and the switch K3 to be turned off, so that the input power supply U charges the inductor L; after charging is completed, the control circuit controls the switches K1 and K2 to be turned off and the switch K3 to be turned on, so that the inductor L discharges to the positive power supply filter capacitor C2 through the positive power supply output rectifier diode D2 to output a positive voltage. During the second charge / discharge cycle, the control circuit controls switches K1 and K2 to be turned on and switch K3 to be turned off, so that the input power supply U charges the inductor L; after charging is completed, the control circuit controls switches K1 and K3 to be turned off and switch K2 to be turned on, so that the inductor L discharges to the negative power supply filter capacitor C1 through the negative power supply output rectifier diode D1 to output a negative voltage.

2. The interleaved BUCK-BOOST positive and negative switching power supply topology circuit according to claim 1, characterized in that, The control circuit uses only one inductor L to realize a positive voltage to positive and negative voltage regulated switching power supply.

3. The interleaved BUCK-BOOST positive and negative switching power supply topology circuit according to claim 1, characterized in that, The control circuit controls the current of inductor L in each charge and discharge cycle. Under unbalanced load, it needs to operate in discontinuous conduction mode (DCM).

4. The interleaved BUCK-BOOST positive and negative switching power supply topology circuit according to claim 1, characterized in that, The topology circuit also includes a feedback loop and an error amplifier, used to adjust the charging time of inductor L in the first charge-discharge cycle and / or the second charge-discharge cycle according to the output value of the positive voltage and / or negative voltage, so as to achieve regulated output.

5. The interleaved BUCK-BOOST positive and negative switching power supply topology circuit according to claim 1, characterized in that, The switches K1, K2, and K3 are transistor switches.

6. A control method for an interleaved BUCK-BOOST positive and negative switching power supply topology circuit based on any one of claims 1 to 5, characterized in that, Includes the following steps: a. In the first charge / discharge cycle, control switches K1 and K2 are turned on to charge inductor L; b. After the first charge-discharge cycle ends, control switches K1 and K2 are turned off, and control switch K3 is turned on, so that inductor L discharges through positive power output rectifier diode D2 to positive power filter capacitor C2 to generate positive power output; c. In the second charge / discharge cycle, control switches K1 and K2 are turned on to recharge inductor L; d. To end the second charge / discharge cycle, control switches K1 and K3 are turned off, and control switch K2 is turned on, so that inductor L discharges through negative power supply output rectifier diode D1 to negative power supply filter capacitor C1 to generate negative power supply output. e. Repeat steps a to d above to achieve continuous output of positive and negative power supplies.

Images