CN211791272U - Buck converter based on low-side switch - Google Patents
Buck converter based on low-side switch Download PDFInfo
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- CN211791272U CN211791272U CN202020692539.9U CN202020692539U CN211791272U CN 211791272 U CN211791272 U CN 211791272U CN 202020692539 U CN202020692539 U CN 202020692539U CN 211791272 U CN211791272 U CN 211791272U
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Abstract
The utility model relates to a power electronics direct current-direct current transform technical field discloses a Buck converter based on low limit switch, including the power conversion circuit who comprises full-control type switching device Q, diode D, inductance L and filter capacitance C, output voltage/electric current, current detection circuit and be used for controlling the drive control circuit of full-control type switching device Q switch, the public end and the input ground of full-control type switching device Q are connected, the other end and filter inductance are connected; the method adopts a double closed loop feedback control mode of output voltage/current and Q current of a switching device; the output voltage/current sampling is realized by a differential sampling circuit. The low-side Buck converter simplifies the problem of complex floating drive in the traditional Buck converter, the problem that the sampling circuit and the negative end of the output voltage are not grounded is solved by adopting the differential sampling circuit for the output voltage/current, the switching loss is low, the conversion efficiency is improved, and high-efficiency conversion is realized.
Description
Technical Field
The invention relates to the technical field of power electronic direct current-direct current conversion, in particular to a Buck converter based on a low-side switch.
Background
The Buck converter is a common one in a basic topology structure of direct current-direct current conversion, and is a common input-output non-isolated power electronic conversion circuit for performing voltage reduction conversion on input voltage. Buck converter has advantages such as simple structure, circuit maturity are stable, and the Buck switching power supply who constitutes by Buck converter is widely used in fields such as consumer electronics, domestic appliance. The common terminal of the control signal of the fully-controlled switching device in the conventional Buck circuit (such as the source S of the MOSFET) is usually not in common with the input power supply of the Buck converter, so that the control terminal of the power switching device and the reference ground of the PWM control circuit cannot be connected, and the floating drive problem of the Buck circuit occurs.
The current common scheme for solving the Buck circuit floating drive problem is summarized into two modes: the first type adopts the opto-coupler isolation drive mode, and PWM control circuit links to each other with power circuit input output's ground promptly, and PWM signal output is connected to the primary side of opto-coupler, and the PWM signal of opto-coupler secondary side output is used for driving the power device switch, and the characteristic of the primary side secondary side electrical isolation of opto-coupler is used to this type of scheme, solves the superficial problem of driving of Buck circuit high-end switch device, but this type of scheme has following problem: firstly, an added optocoupler needs to introduce a power supply isolated from input on the secondary side, so that the cost and complexity of the Buck power supply are increased, and in addition, the optocoupler generates large time delay on the front edge and the rear edge of a PWM driving pulse, so that the Buck power supply cannot adapt to a high-frequency PWM driving mode and the output control characteristic of the Buck power supply is influenced; the reference end of the control circuit is connected with the control public end of the switch device in the second scheme, the output voltage is fed back to the control circuit unit to achieve output voltage stabilization control in an isolation sampling mode combining the control chip and the optical coupler, the related control chip and the power supply of the control circuit are still needed in the second scheme, the complexity of the Buck power supply is increased, and the overall reliability is reduced.
Disclosure of Invention
The purpose of the invention is as follows: to the problem that exists among the prior art, the utility model provides a Buck converter based on low limit switch, this circuit have overcome the complicated with high costs shortcoming of circuit of traditional Buck converter floating drive scheme, realize the working method of the stable output of voltage electric current double closed-loop feedback control.
The technical scheme is as follows: the utility model provides a Buck converter based on low limit switch, include the power conversion circuit, output voltage/electric current, the differential sampling circuit of output voltage/electric current, the current detection circuit that flow through full-control type switching device Q, the drive control circuit who is used for controlling full-control type switching device Q switch including integrated PWM chip and for the voltage stabilizing circuit of integrated PWM chip power supply that are constituteed by full-control type switching device Q, diode D, inductance L and filter capacitance C, full-control type switching device Q connects in the negative pole of input direct current and diode D's positive pole, inductance L one end links to each other with the negative pole of output load end, and the other end links to each other with diode D's positive pole, and filter capacitance C one end links to each other with the negative pole of output load end, and the other end links to each other with the positive pole of output load end; the Buck converter of the low-side switch adopts a double closed-loop control system for outputting voltage/current and Q current of a full-control type switching device.
Furthermore, the positive electrode of the input side of the converter is connected with the positive electrode of the output side of the converter, and the negative electrode of the input side of the double closed-loop control system of the converter is used as a reference ground potential.
Furthermore, the double closed-loop control system comprises a differential sampling circuit for outputting voltage/current, a current detection circuit flowing through a full-control type switching device Q and an integrated PWM chip; the Buck converter outputs a differential sampling circuit to obtain load voltage/current and feeds the load voltage/current back to a voltage feedback end of a PWM chip of the integrated control chip, the current flowing through the full-control type switching device Q is sampled by a current detection circuit and fed back to a current detection port of the integrated PWM chip, and a PWM signal obtained through voltage and current closed-loop operation is used for driving the full-control type switching device Q.
Further, the current detection circuit is a current sampling resistor or a current transformer.
Has the advantages that:
the common terminal of the full-control type switching device Q of the Buck circuit of the low-side switch (S pole of the full-control type switching device Q) is connected with the input ground through the sampling resistor (current detection circuit), the PWM control signal output by the PWM control chip taking the input ground as the reference can directly drive the full-control type switching device Q, a complex floating drive circuit of a traditional Buck converter is not needed, the circuit cost is reduced, the reliability is improved, a differential sampling circuit is adopted for output voltage/current, the structure of the whole circuit is simplified, and the complex power supply requirement caused by the fact that the input and the output are not in common is avoided.
Drawings
Fig. 1 is a block diagram of a low-side switch Buck-based circuit of the present invention.
Fig. 2 is a circuit diagram of a voltage-current double closed-loop control system of the low-side Buck converter.
Fig. 3 shows waveforms of driving signals and input and output voltages of the Buck converter according to the present invention operating in a closed-loop voltage stabilization mode.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings.
The utility model discloses mainly be in order to overcome the complicated with high costs shortcoming of circuit of traditional Buck converter floating drive scheme, disclose a Buck converter based on low limit switch, see figure 1 and figure 2, include the power conversion circuit who comprises full accuse type switching device Q, diode D, inductance L and filter capacitance C, output voltage/electric current, the current detection circuit who flows through full accuse type switching device Q, the voltage stabilizing circuit who is used for controlling the drive control circuit of full accuse type switching device Q switch and supplies power for integrated PWM chip that comprises integrated PWM chip.
The fully-controlled switching device Q is connected with the negative electrode of the input direct current and the anode of the diode D, the common end of the fully-controlled switching device Q is connected with the input ground, and the other end of the fully-controlled switching device Q is connected with the filter inductor L. One end of the inductor L is connected with the negative electrode of the output load end, the other end of the inductor L is connected with the anode of the diode D, and the filter capacitor C is connected with the direct current output side. Referring to fig. 2, one end of the filter capacitor C is connected to the negative electrode of the output load terminal, and the other end is connected to the positive electrode of the output load terminal.
The Buck converter of the low-side switch adopts a double closed-loop control system for outputting voltage/current and current flowing through a full-control type switching device Q.
The positive pole of the input side of the converter is connected with the positive pole of the output side of the converter, and the negative pole of the input side of the current double closed-loop control system of the converter is used as a reference ground potential.
The current double closed-loop control system comprises a differential sampling circuit for outputting voltage/current, a current detection circuit flowing through a full-control type switching device Q and an integrated PWM chip. The Buck converter outputs a differential sampling circuit to obtain load voltage/current (Vof/Iof, wherein Vof represents load voltage, Iof represents load current) and feeds the load voltage/current back to a voltage feedback end of the integrated control chip, current flowing through the full-control type switching device Q is sampled by a current detection circuit and fed back to a current detection port of the PWM integrated chip, and a PWM signal obtained through voltage and current closed-loop operation is used for driving the full-control type switching device Q.
In the embodiment, the current detection circuit is a current sampling resistor Rs, and a current transformer can be adopted in the application occasions with higher power.
In this embodiment, when the input dc voltage is 48V, the filter inductor 100uH, the filter capacitor 110uF, and the load resistor RL are 10 Ω (load in fig. 1), the current sampling resistor Rs is 0.1 Ω.
Referring to fig. 2, fig. 2 is a circuit diagram of a voltage-current double closed-loop control system of a low-side Buck converter, wherein a power supply is a direct-current power supply, the voltage of the direct-current power supply is 48V, and a current detection circuit (a current sampling resistor Rs) flowing through a fully-controlled switching device Q is connected with an input ground. And the current flowing through the fully-controlled switching device Q is sampled by a current sampling resistor and fed back to a current detection port of the integrated PWM chip. The voltage/current of the output side is sampled by the differential sampling circuit on the right side and fed back to the PWM driving circuit on the lower end (namely fed back to the voltage feedback end of the PWM chip of the integrated control chip). And the PWM signal obtained through voltage and current closed-loop operation is used for driving the power switch tube Q.
Fig. 3 shows the output voltage, the input voltage and the PWM driving voltage waveform of the low-side switching device (MOSFET), where Ui is the input voltage, Uo is the output voltage, and PWM is the driving PWM signal of the fully-controlled switching device Q.
The Buck converter based on the low-side switch realizes the constant-voltage constant-current control of output direct current by adopting a current double-closed-loop control mode that output voltage/current flows through a fully-controlled switching device Q, and the low-side switch and the output differential sampling working mode ensure that a signal sent by a PWM chip directly drives the fully-controlled switching device Q, simplify a driving circuit of the Buck converter, optimize the circuit structure of the Buck converter and improve the system reliability. Therefore, the method has wide application prospect in the occasions of low-power non-isolated DC-DC conversion such as a secondary power supply of a communication system, an industrial control power supply and the like.
The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose of the embodiments is to enable those skilled in the art to understand the contents of the present invention and to implement the present invention, which cannot limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered by the protection scope of the present invention.
Claims (4)
1. A Buck converter based on a low-side switch is characterized by comprising a power conversion circuit, a differential sampling circuit, a current detection circuit, a driving control circuit and a voltage stabilizing circuit, wherein the power conversion circuit consists of a fully-controlled switching device Q, a diode D, an inductor L and a filter capacitor C; the Buck converter of the low-side switch adopts a double closed-loop control system for outputting voltage/current and Q current of a full-control type switching device.
2. The low-side switch-based Buck converter according to claim 1, wherein an input side positive electrode and an output side positive electrode of the converter are connected, and a double closed-loop control system of the converter takes a negative electrode of the input side as a reference ground potential.
3. The low-side switch-based Buck converter according to claim 2, wherein the double closed-loop control system comprises a differential sampling circuit outputting voltage/current, a current detection circuit flowing through a fully-controlled switching device Q and an integrated PWM chip; the Buck converter differential sampling circuit obtains load voltage/current and feeds the load voltage/current back to a voltage feedback end of a PWM chip of the integrated control chip, current flowing through the full-control type switching device Q is sampled by the current detection circuit and fed back to a current detection port of the integrated PWM chip, and a PWM signal obtained through voltage and current closed-loop operation is used for driving the full-control type switching device Q.
4. The low-side switch based Buck converter according to claim 3, wherein the current detection circuit is a current sampling resistor or a current transformer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020692539.9U CN211791272U (en) | 2020-04-29 | 2020-04-29 | Buck converter based on low-side switch |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020692539.9U CN211791272U (en) | 2020-04-29 | 2020-04-29 | Buck converter based on low-side switch |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN211791272U true CN211791272U (en) | 2020-10-27 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202020692539.9U Expired - Fee Related CN211791272U (en) | 2020-04-29 | 2020-04-29 | Buck converter based on low-side switch |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN211791272U (en) |
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2020
- 2020-04-29 CN CN202020692539.9U patent/CN211791272U/en not_active Expired - Fee Related
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| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20201027 Termination date: 20210429 |