A step-down conversion circuit and a switching power supply

Abstract

The application discloses a voltage reduction conversion circuit and a switching power supply. It belongs to the technical field of power electronic devices, and the circuit comprises a power module, an energy storage module, a freewheeling module and a switching module. The first end of the energy storage module is connected with the positive end of the power module, and the second end of the energy storage module is connected with the first end of an external load. The first end of the freewheeling module is connected with the second end of the external load, and the second end of the freewheeling module is connected with the first end of the energy storage module. The first end of the switching module is connected with a first ground end, and the second end of the switching module is connected with the external load and a second ground end respectively. The first ground end is connected with the negative end of the power module. The switching module is used for being turned on or turned off according to a received driving signal. According to the embodiment of the application, the driving circuit of the power switch tube is simplified, and the cost of the driving circuit is reduced.

Description

Technical Field

[0001] This application belongs to the field of power electronics technology, and in particular relates to a step-down converter circuit and a switching power supply. Background Technology

[0002] A buck converter circuit is a DC-to-DC voltage reduction circuit. A typical buck converter circuit includes a power switch, capacitor, inductor, and diode. The power switch is usually a transistor, MOSFET, or IGBT to turn the current on or off. The inductor stores electrical energy, and the capacitor charges and discharges. The specific circuit connection structure is as follows: Figure 1 As shown.

[0003] In related technologies, as... Figure 1 As shown, the switching units of the buck converter circuit are all controlled by the upper transistor, that is, the power switching transistor is placed on the positive circuit Vin+, and then the power switching transistor is driven by the control chip or microcontroller to control the buck converter circuit. Taking the MOSFET as an example, in the process of driving the power switching transistor, a voltage higher than the source voltage is required for the power switching transistor to conduct. If the voltage of the positive circuit Vin+ is low, a boost circuit or an expensive P-type power switching transistor is required to drive the buck converter circuit, which will lead to a complex driving circuit and excessive cost. Utility Model Content

[0004] This application provides a buck converter circuit and a switching power supply, which can simplify the driving circuit of the power switching transistor and reduce the cost of the driving circuit.

[0005] On one hand, embodiments of this application provide a buck converter circuit, the circuit including:

[0006] Power module;

[0007] An energy storage module, wherein a first terminal of the energy storage module is connected to the positive terminal of the power supply module, and a second terminal of the energy storage module is connected to the first terminal of an external load;

[0008] A freewheeling module, wherein a first end of the freewheeling module is connected to a second end of an external load, and a second end of the freewheeling module is connected to a first end of the energy storage module;

[0009] A switching module, wherein a first terminal of the switching module is connected to a first ground terminal, and a second terminal of the switching module is connected to a second ground terminal of an external load, wherein the first ground terminal is connected to the negative terminal of the power supply module; the switching module is used to turn on or off according to a received drive signal.

[0010] Optionally, the switching module includes:

[0011] A power switching transistor, wherein a first terminal of the power switching transistor is connected to the first ground terminal, a second terminal of the power switching transistor is connected to the second ground terminal, and a control terminal of the power switching transistor is connected to a drive signal terminal;

[0012] The drive signal terminal is used to receive drive signals, which include pulse width modulation signals.

[0013] Optionally, the power switch is an N-type transistor, which includes any one of a metal-oxide-semiconductor field-effect transistor (MOSFET), a power transistor, or an insulated-gate bipolar transistor (IGBT).

[0014] Optionally, the switch module further includes:

[0015] A gate drive resistor is connected between the drive signal terminal and the control terminal of the power switch transistor.

[0016] A gate-source resistor is connected between the first terminal of the power switch and the control terminal of the power switch.

[0017] Optionally, the buck converter circuit further includes:

[0018] A first filtering module, wherein a first end of the first filtering module is connected to the positive terminal of the power supply module, and a second end of the first filtering module is connected to the negative terminal of the power supply module.

[0019] Optionally, the first filtering module includes:

[0020] A first filter capacitor, wherein a first terminal of the first filter capacitor is connected to the positive terminal of the power supply module, and a second terminal of the first filter capacitor is connected to the negative terminal of the power supply module.

[0021] Optionally, the buck converter circuit further includes:

[0022] The second filtering module has its first end connected to the second end of the energy storage module, and its second end connected to the second end of the switching module.

[0023] Optionally, the second filtering module includes:

[0024] The second filter capacitor has its first end connected to the second end of the energy storage module and its second end connected to the second end of the switching module.

[0025] Optionally, the continuing current module includes:

[0026] A freewheeling diode, wherein the anode of the freewheeling diode is connected to the second terminal of the external load, and the cathode of the freewheeling diode is connected to the first terminal of the energy storage module.

[0027] On the other hand, embodiments of this application provide a switching power supply, which includes a buck converter circuit as described in the first aspect.

[0028] The buck converter circuit and switching power supply of this application embodiment can connect the switching module to the negative terminal of the power supply module when designing a buck DC-DC converter circuit. That is, the switching module is placed between the negative terminal of the power supply module and the negative terminal of the external load. This can reduce the driving voltage for the switching module to turn on. Compared with the driving circuits in related technologies that require boost circuits or isolation driving circuits, this application can simplify the circuit design. When the switching module is turned on, there is no need for a boost circuit to increase the gate voltage of the power switch. Only a driving signal is needed to turn on the switching module, thus reducing the cost of the driving circuit. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a circuit diagram of a step-down converter circuit in related technologies;

[0031] Figure 2 This is a schematic diagram of the buck converter circuit provided in one embodiment of this application;

[0032] Figure 3 This is a circuit schematic diagram of a buck converter circuit provided in one embodiment of this application.

[0033] Explanation of reference numerals in the attached diagram: 1. Power supply module; 2. Energy storage module; 3. Freewheeling module; 4. Switching module; 5. First filter module; 6. Second filter module. Detailed Implementation

[0034] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0035] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0036] To understand the innovative aspects of this application, a brief description of the background technology is provided below.

[0037] See Figure 1 , Figure 1 This diagram illustrates a common buck converter circuit, which includes a switch Q1, a capacitor C1, an inductor L1, and a diode D1. The power switch Q1 is used to turn the current on and off. The inductor L1 converts electrical energy into magnetic energy for storage and can also convert magnetic energy back into electrical energy. The capacitor C1 is used for charging and discharging. During operation, when the inductor voltage is greater than the target voltage, the switch Q1 is turned off, and the inductor discharges. When the inductor voltage is lower than the required output voltage, the switch Q1 is turned on, and the inductor charges. During this process, a gate voltage higher than the source voltage is required to control the conduction state of the switch Q1. However, since the switch Q1 is directly connected to the positive terminal of the power supply, a boost circuit is needed to ensure the gate voltage is higher than the source voltage. This undoubtedly increases the complexity and cost of the buck converter circuit. Therefore, a buck converter circuit is urgently needed to simplify the circuit structure and reduce circuit costs.

[0038] To address the problems of existing technologies, embodiments of this application provide a buck converter circuit and a switching power supply. In the circuit design of the buck DC-DC converter, connecting the switching module to the negative terminal of the power supply module, i.e., placing the switching module between the negative terminal of the power supply module and the negative terminal of the external load, reduces the drive voltage required to turn on the switching module. Compared to related technologies that require boost circuits or isolation drive circuits, this application simplifies circuit design. When the switching module is turned on, there is no need for a boost circuit to increase the gate voltage of the power switch transistor; only a drive signal is needed to turn on the switching module, reducing the cost of the drive circuit.

[0039] See Figure 2 , Figure 2This application provides a structural block diagram of a buck converter circuit, which may include:

[0040] Power module 1 is used to provide converted power;

[0041] Energy storage module 2, with its first end connected to the positive terminal of power module 1, and its second end connected to the first end of an external load;

[0042] The first end of the freewheeling module 3 is connected to the second end of the external load, and the second end of the freewheeling module 3 is connected to the first end of the energy storage module 2.

[0043] The switch module 4 has a first end connected to the first grounding terminal and a second end connected to the second end of the external load and the second grounding terminal, respectively. The first grounding terminal is connected to the negative terminal of the power supply module 1. The switch module 4 is used to turn on or off according to the received drive signal.

[0044] In this embodiment, when designing the buck DC-DC converter circuit, the switch module 4 is connected to the negative terminal of the power supply module 1, that is, the switch module 4 is placed between the negative terminal of the power supply module 1 and the negative terminal of the external load. This reduces the driving voltage required to turn on the switch module 4. Compared with the driving circuits in related technologies that require boost circuits or isolation driving circuits, this application simplifies the circuit design. When the switch module 4 is turned on, there is no need for a boost circuit to increase the gate voltage of the power switch transistor. The switch module 4 can be turned on using only a driving signal, thus reducing the cost of the driving circuit.

[0045] As an optional implementation, the power module 1 may include any one of a capacitor, a battery, or a pre-amplifier power ground output.

[0046] In some embodiments, the energy storage module 2 may include an inductor L2, with a first end of the inductor L2 connected to the positive terminal of the power module 1 and a second end of the inductor L2 connected to the first end of an external load.

[0047] In this embodiment, inductor L2 stores and releases energy during the switching module 4's on or off process. Specifically, when the switching module 4 is on, inductor L2 enables the current to increase linearly and converts electrical energy into magnetic energy for storage, while simultaneously supplying power to the load RL. When the switching module 4 is off, since the current across inductor L2 cannot change abruptly, inductor L2 can release the magnetic energy by converting it into electrical energy through the freewheeling module 3, thereby enabling the current to decrease linearly.

[0048] In some embodiments, the freewheeling module 3 may include a freewheeling diode D2, the anode of which is connected to the second terminal of an external load, and the cathode of which is connected to the first terminal of an inductor L2. In this embodiment, the freewheeling diode D2 is used to provide a freewheeling path for the inductor L2 to release energy when the switching module 4 is turned off.

[0049] In the process of releasing energy from inductor L2, the current flows sequentially from inductor L2 to the external load, and then from the external load back to inductor L2 through freewheeling diode D2, thus completing a closed loop and releasing energy.

[0050] Reference Figure 3 In some other embodiments, the switch module 4 may include:

[0051] The power switch Q2 has its first terminal connected to the first ground terminal, its second terminal connected to the second ground terminal, and its control terminal connected to the drive signal terminal.

[0052] In this embodiment, the power switch Q2 is directly connected to the negative terminal of the power module 1, which can reduce the turn-on voltage of the power switch Q2, thereby simplifying the circuit design and reducing costs.

[0053] Specifically, in this embodiment, the power switch Q2 is an N-type transistor. Compared with a P-type transistor, the N-type transistor has a lower device cost, which reduces the overall device cost of the buck converter circuit.

[0054] The following explanation uses the metal-oxide-semiconductor field-effect transistor (MOSFET) as an example.

[0055] In some other embodiments, the power switch Q2 may include any one of a metal-oxide-semiconductor field-effect transistor (MOSFET), a power transistor, or an insulated-gate bipolar transistor (IGBT).

[0056] In this embodiment, in order to better drive the power switch Q2 to work, the switching module 4 may further include:

[0057] The gate drive resistor Rg is connected between the drive signal terminal and the control terminal of the power switch Q2.

[0058] The gate-source resistor Rgs is connected between the first terminal of the power switch Q2 and the control terminal of the power switch Q2.

[0059] In this embodiment, the gate drive resistor Rg can limit the gate current to prevent overload of the drive signal source, protect the circuit, eliminate gate oscillation of the power switch Q2, and adjust the switching speed of the power switch Q2. The gate-source resistor Rgs can provide a low-resistance path when the power switch Q2 is turned off, ensuring that the power switch Q2 is reliably turned off when the drive signal terminal is floating.

[0060] When the drive signal drives the power switch Q2 to turn on, the drive signal is a high-level signal. The high-level signal increases the gate voltage of the power switch Q2 through the gate drive resistor Rg, and the power switch Q2 turns on at this time. When the drive signal drives the power switch Q2 to turn off, the drive signal is a low-level signal. The gate voltage is pulled down through the gate drive resistor Rg, and the power switch Q2 is reliably turned off.

[0061] In some other embodiments, in order to maintain a stable input voltage to power module 1, the buck converter circuit further includes:

[0062] The first filter module 5 has its first end connected to the positive terminal of the power supply module 1, and its second end connected to the negative terminal of the power supply module 1.

[0063] The first filter module 5 can stabilize the input voltage of the power supply module 1 and reduce voltage fluctuations and ripples at the input terminal.

[0064] Specifically, the first filtering module 5 may include: a first filtering capacitor Cin, the first end of the first filtering capacitor Cin being connected to the positive terminal of the power supply module 1, and the second end of the first filtering capacitor being connected to the negative terminal of the power supply module 1.

[0065] In this embodiment, the first filter capacitor Cin can be used as a filter device to stabilize the input voltage, reduce voltage fluctuations and ripples generated when the power module 1 outputs voltage, and ensure the safe and stable operation of the circuit.

[0066] In some other embodiments, to stabilize the output voltage of the buck converter circuit, the buck converter circuit may further include:

[0067] The second filter module 6 has its first end connected to the second end of the energy storage module 2, and its second end connected to the second end of the switch module 4.

[0068] In this embodiment, the second filter module 6 can stabilize the output voltage of the buck converter circuit and reduce voltage fluctuations and ripples at the output of the buck converter circuit.

[0069] As a specific example, the second filtering module 6 may include:

[0070] The second filter capacitor Co has its first end connected to the second end of the energy storage module 2 and its second end connected to the second end of the switch module 4.

[0071] In this example, the second filter capacitor Co acts as a filter device, which can stabilize the output voltage of the buck converter circuit and reduce voltage fluctuations and ripples at the output of the buck converter circuit.

[0072] To better understand the control principle of this application, the working principle of the power switch Q2 being turned on and off is illustrated below with a specific example.

[0073] Specifically, taking the PWM signal as the driving signal as an example, when the PWM signal is a high-level signal, the power switch Q2 is saturated and turned on, connecting the first ground terminal and the second ground terminal. At this time, the freewheeling diode D1 is reverse cut off, which is equivalent to an open circuit. At this time, the current output from the positive terminal Vin of the power module 1 returns to the first ground terminal through the inductor L2, the second filter capacitor Co and the power switch Q2 in sequence, charging the second filter capacitor Co. At the same time, it returns to the negative terminal of the power module 1 through the inductor L2, the external load RL and the power switch Q2 in sequence, supplying power to the external load. At this time, the current of the inductor L2 increases linearly. Meanwhile, the first filter capacitor Cin charges the second filter capacitor Co in sequence through the inductor L2, the second filter capacitor Co, the power switch Q2 and the first filter capacitor Cin. In addition, it supplies power to the external load RL in sequence through the inductor L2, the external load RL, the power switch Q2 and the first filter capacitor Cin.

[0074] In another example, when the PWM signal is low, the power switch Q2 is turned off. At this time, the first ground terminal and the second ground terminal are disconnected. Since the current of inductor L2 cannot change abruptly, an induced voltage is generated across inductor L2. At this time, inductor L2 is forward-biased through freewheeling diode D2 to provide freewheeling current to inductor L2. The specific current flow is as follows: power module 1 charges the first filter capacitor Cin, that is, power module 1 and the first filter capacitor Cin form a loop. Inductor L2 supplies power to the external load RL, that is, the current output by inductor L2 passes through the external load RL and freewheeling diode D2 in sequence and returns to inductor L2 to supply power to the external load RL. At the same time, the second filter capacitor Co forms a loop with the external load RL, and the second filter capacitor Co supplies power to the external load RL.

[0075] In the example above, the average value of the output voltage can be adjusted by controlling the duty cycle of the PWM signal to achieve step-down output.

[0076] It is worth noting that the buck converter circuit provided in this application embodiment can reduce the cost of the power switch Q2, eliminating the need for expensive P-type transistors. In addition, since the source of the power switch Q2 is directly connected to the negative terminal of the power module 1, the cost of the drive circuit for the power switch Q2 can be reduced, eliminating the need for an isolated drive circuit and additional boost circuits to drive the power switch Q2. Furthermore, the buck converter circuit provided in this application embodiment can simplify circuit design and enable direct control of the PWM signal.

[0077] In other embodiments, this application also provides a switching power supply, including the buck converter circuit and controller described above.

[0078] When using this switching power supply, the controller can output a PWM signal, which is used as a drive signal to turn on the power switch Q2, so as to control the power module 1 to supply power to the external load.

[0079] Correspondingly, due to the adoption of the above-mentioned step-down conversion circuit, the circuit structure of the corresponding switching power supply is simple and the cost is reduced.

[0080] The above are merely specific embodiments of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A step-down converter circuit, characterized in that, include: Power module (1); Energy storage module (2), the first end of which is connected to the positive terminal of power module (1), and the second end of which is connected to the first end of external load; A freewheeling module (3) is provided, wherein the first end of the freewheeling module (3) is connected to the second end of an external load, and the second end of the freewheeling module (3) is connected to the first end of the energy storage module (2). A switch module (4) is provided, wherein the first end of the switch module (4) is connected to the first grounding terminal, and the second end of the switch module (4) is connected to the second grounding terminal of the external load, wherein the first grounding terminal is connected to the negative terminal of the power supply module (1); the switch module (4) is used to turn on or off according to the received drive signal.

2. The step-down converter circuit according to claim 1, characterized in that, The switching module (4) includes: A power switching transistor, wherein a first terminal of the power switching transistor is connected to the first ground terminal, a second terminal of the power switching transistor is connected to the second ground terminal, and a control terminal of the power switching transistor is connected to a drive signal terminal; The drive signal terminal is used to receive drive signals, which include pulse width modulation signals.

3. The step-down converter circuit according to claim 2, characterized in that, The power switch is an N-type transistor, which includes any one of a metal-oxide-semiconductor field-effect transistor (MOSFET), a power transistor, or an insulated-gate bipolar transistor (IGBT).

4. The step-down converter circuit according to claim 2, characterized in that, The switching module (4) also includes: A gate drive resistor is connected between the drive signal terminal and the control terminal of the power switch transistor. A gate-source resistor is connected between the first terminal of the power switch and the control terminal of the power switch.

5. The step-down converter circuit according to any one of claims 1-4, characterized in that, The step-down converter circuit also includes: The first filter module (5) has its first end connected to the positive terminal of the power supply module (1) and its second end connected to the negative terminal of the power supply module (1).

6. The step-down converter circuit according to claim 5, characterized in that, The first filtering module (5) includes: A first filter capacitor, the first end of which is connected to the positive terminal of the power module (1), and the second end of which is connected to the negative terminal of the power module (1).

7. The step-down converter circuit according to any one of claims 1-4, characterized in that, The step-down converter circuit also includes: The second filter module (6) has its first end connected to the second end of the energy storage module (2) and its second end connected to the second end of the switch module (4).

8. The step-down converter circuit according to claim 7, characterized in that, The second filtering module (6) includes: The second filter capacitor has its first end connected to the second end of the energy storage module (2) and its second end connected to the second end of the switch module (4).

9. The step-down converter circuit according to any one of claims 1-4, characterized in that, The continuous flow module (3) includes: A freewheeling diode, the anode of which is connected to the second end of the external load, and the cathode of which is connected to the first end of the energy storage module (2).

10. A switching power supply, characterized in that, Includes the buck converter circuit as described in any one of claims 1-9.

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