Voltage conversion circuit and switching power supply

Abstract

The embodiment of the invention discloses a voltage conversion circuit and a switching power supply. A control module magnetizes or demagnetizes an inductor by controlling alternate conduction of a main switching tube and a follow current switching tube in a voltage conversion module, and charges and discharges a first capacitor. A virtual inductive current ripple signal is constructed through a virtual ripple generation module, and the virtual inductive current ripple signal replaces ESR information on a first capacitor to be superposed on a feedback voltage, so that after the feedback voltage is superposed with the virtual inductive current ripple signal, the phase difference between the feedback voltage and an inductive current is reduced, and the feedback voltage is reduced. The control module outputs a first control signal according to a virtual inductive current ripple signal and a feedback voltage to control the conduction time of the main switching tube and the follow current switching tube, so that the problem of harmonic oscillation caused by a time-lag effect between an inductive current and the output voltage on the first capacitor is solved, and the generation of harmonic waves is suppressed; the stability of the output voltage of the voltage conversion circuit is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of voltage conversion, and in particular to a voltage conversion circuit and a switching power supply. Background Art

[0002] Among the various control methods of switching power supplies, constant on time (COT) control is a control technology based on output voltage ripple and without error amplifier and compensation network, with variable switching frequency. Switching power supplies based on COT control can reduce switching frequency and reduce the proportion of switching losses, and have a wide range of applications in improving system light load efficiency; at the same time, compared with voltage mode control and current mode control, switching power supplies based on COT control have the characteristics of simple circuit structure and fast load transient response.

[0003] In traditional switching power supplies based on COT control, due to the time lag effect between capacitor voltage and inductor current, when using capacitors with low equivalent series resistance (ESR), subharmonic oscillation will occur in the system, resulting in loop instability. Summary of the invention

[0004] The present invention provides a voltage conversion circuit and a switching power supply to improve the harmonic oscillation problem caused by the time lag effect of capacitor voltage and inductor current and enhance output stability.

[0005] According to one aspect of the present invention, there is provided a voltage conversion circuit, comprising: a voltage conversion module, a control module, a voltage feedback module and a virtual ripple generation module;

[0006] The voltage conversion module includes a main switch tube, a freewheeling switch tube and a first output storage unit. The main switch tube and the freewheeling switch tube are respectively connected to the first output storage unit. The main switch tube is used to transmit electric energy to the first output storage unit when it is turned on. The freewheeling switch tube is used to connect the discharge circuit of the first output storage unit when it is turned on. The first output storage unit includes an inductor and a first capacitor. The first output storage unit is connected to the output end of the voltage conversion module.

[0007] The voltage feedback module is connected to the output end of the voltage conversion module and the control module respectively, and is used to output a feedback voltage to the control module according to the output voltage of the voltage conversion module;

[0008] The virtual ripple generating module is connected to the control module, and is used to generate a virtual inductor current ripple signal corresponding to the current ripple signal of the inductor according to the first control signal output by the control module;

[0009] The control module is connected to the main switch tube and the freewheeling switch tube, and is used to control the conduction time of the main switch tube and the freewheeling switch tube according to the feedback voltage and the virtual inductor current ripple signal.

[0010] Optionally, the virtual ripple generating module includes a level shifting circuit and a generating circuit, the level shifting circuit is connected to the control module and the generating circuit respectively, and is used to convert a first control signal in a first voltage domain output by the control module to obtain a second control signal in a second voltage domain;

[0011] The generating circuit is used for generating a virtual inductor current ripple signal corresponding to the current ripple signal of the inductor according to the second control signal.

[0012] Optionally, the generating circuit includes a first switch tube, a second switch tube, a second output storage unit, a filtering unit and a subtractor;

[0013] The first end of the second output storage unit is connected to the first switch tube and the second switch tube respectively, the first switch tube and the second switch tube are respectively used to be turned on or off according to the second control signal, the first switch tube is used to transmit electric energy to the second output storage unit when turned on, and the second switch tube is used to connect the discharge circuit of the second output storage unit when turned on; wherein the first switch tube has the same conduction period as the main switch tube, and the second switch tube has the same conduction period as the freewheeling switch tube;

[0014] The first end of the filter unit is connected to the second end of the second output storage unit, and the filter unit is used to filter the first voltage of the second output storage unit to obtain a second voltage;

[0015] The subtractor is connected to the second end of the second output storage unit and the output end of the filter unit respectively, and is used to obtain a voltage ripple signal according to the difference between the first voltage and the second voltage, and the voltage ripple signal is used as a virtual inductor current ripple signal.

[0016] Optionally, the second output storage unit includes a first resistor and a second capacitor, the first end of the first resistor is respectively connected to the first switch tube and the second switch tube, the second end of the first resistor is connected to the first end of the second capacitor, and the second end of the second capacitor is grounded; the first end of the second capacitor serves as the second end of the second output storage unit;

[0017] The filtering unit includes a second resistor and a third capacitor, the first end of the second resistor is connected to the second end of the first resistor, the second end of the second resistor is connected to the first end of the third capacitor, and the second end of the second capacitor is grounded; the first end of the third capacitor serves as the output end of the filtering unit.

[0018] Optionally, the control module includes a first output end and a second output end, the first output end is connected to the gate of the main switch tube, the second output end is connected to the gate of the freewheeling switch tube, the first control signal includes a first sub-control signal output by the control module to the first output end, and a second sub-control signal output to the second output end; the first pole of the main switch tube is connected to the second pole of the freewheeling switch tube, the first pole of the main switch tube is also connected to the inductor, the second pole of the main switch tube is connected to the input voltage, and the first pole of the freewheeling switch tube is grounded;

[0019] The second control signal includes a third sub-control signal and a fourth sub-control signal;

[0020] The level transfer circuit includes a first transfer unit and a second transfer unit, wherein the input end of the first transfer unit is connected to the first output end, the output end of the first transfer unit is connected to the gate of the first switch tube, the first transfer unit is used to convert the first sub-control signal of the first voltage domain into a third sub-control signal of the second voltage domain; the first switch tube is used to be turned on or off according to the third sub-control signal;

[0021] The input end of the second transfer unit is connected to the second output end, the output end of the second transfer unit is connected to the gate of the second switch tube, and the second transfer unit is used to convert the second sub-control signal of the first voltage domain into a fourth sub-control signal of the second voltage domain; the second switch tube is used to turn on or off according to the fourth sub-control signal.

[0022] Optionally, the first electrode of the first switch tube is connected to the power supply voltage, the second electrode of the first switch tube is connected to the second electrode of the second switch tube, and the first electrode of the second switch tube is grounded;

[0023] The virtual ripple generating module further includes an inverter and a buffer, wherein the input end of the inverter is connected to the first transfer unit, and the output end of the inverter is connected to the gate of the first switch tube;

[0024] The input end of the buffer is connected to the second transfer unit, and the output end of the buffer is connected to the gate of the second switch tube;

[0025] Among them, the first switch tube is a P-type transistor, the second switch tube is an N-type transistor; the main switch tube is an N-type transistor, and the freewheeling switch tube is an N-type transistor.

[0026] Optionally, the control module includes a logic operation unit, a comparator, a conduction time generator and a driving unit;

[0027] The logic operation unit is connected to the virtual ripple generation module, the voltage feedback module and the comparator respectively, and is used to obtain a feedback compensation voltage after performing a logic operation on the virtual inductor current ripple signal and the feedback voltage;

[0028] The non-inverting input terminal of the comparator is connected to the reference voltage, the inverting input terminal of the comparator is connected to the logic operation unit, and the output terminal of the comparator is connected to the conduction time generator;

[0029] The on-time generator is connected to the driving unit, and is used to generate a driving signal according to the output signal of the comparator; the driving unit is used to generate a first control signal according to the driving signal to control the on-time of the main switch tube and the freewheeling switch tube.

[0030] Optionally, the logic operation unit includes a multiplier and an adder, the input of the multiplier is connected to the virtual ripple generation module, the output of the multiplier is connected to the first input of the adder, the second input of the adder is connected to the output of the voltage feedback module, and the output of the adder is connected to the inverting input of the comparator.

[0031] Optionally, the voltage conversion circuit includes a chip, and the control module and the virtual ripple generation module are integrated in the chip.

[0032] According to another aspect of the present invention, a switching power supply is provided, comprising the voltage conversion circuit according to any embodiment of the present invention.

[0033] The technical solution of the embodiment of the present invention is to set a voltage conversion circuit including a voltage conversion module, a control module, a voltage feedback module and a virtual ripple generation module. The control module controls the main switch tube and the freewheeling switch tube in the voltage conversion module to be alternately turned on to magnetize or demagnetize the inductor, and to charge and discharge the first capacitor. The virtual inductor current ripple signal is constructed by the virtual ripple generation module, which is equivalent to constructing the virtual ESR of the first capacitor. The virtual inductor current ripple signal replaces the ESR information on the first capacitor and is superimposed on the feedback voltage, so that after the feedback voltage is superimposed on the virtual inductor current ripple signal, the phase difference with the inductor current is reduced. The control module controls the conduction time of the main switch tube and the freewheeling switch tube according to the virtual inductor current ripple signal and the first control signal outputted in the feedback voltage, improves the harmonic oscillation problem caused by the time lag effect between the inductor current and the output voltage on the first capacitor, suppresses the generation of harmonics, and improves the stability of the output voltage of the voltage conversion circuit.

[0034] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 It is a structural diagram of a Buck converter based on COT control in the related art;

[0037] Figure 2 yes Figure 1 The working timing diagram of the Buck converter shown;

[0038] Figure 3 is a schematic structural diagram of a voltage conversion circuit provided by an embodiment of the present invention;

[0039] Figure 4 is a schematic structural diagram of another voltage conversion circuit provided by an embodiment of the present invention;

[0040] Figure 5 is a schematic structural diagram of another voltage conversion circuit provided by an embodiment of the present invention;

[0041] Figure 6 is a schematic structural diagram of another voltage conversion circuit provided by an embodiment of the present invention;

[0042] Figure 7 yes Figure 6 The working timing diagram of the voltage conversion circuit shown. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0044] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0045] Figure 1 This is a schematic diagram of the structure of the Buck converter based on COT control in the related technology. Figure 2 The Buck converter based on COT control includes a system power stage circuit 101 and a COT control stage circuit 102. The high-side power tube M10 and the low-side power tube M20 in the system power stage circuit 101 are alternately turned on to magnetize and demagnetize the inductor L in the control logic and the driving control system. The comparator of the COT control stage circuit 102 converts the feedback voltage V corresponding to the output voltage VOUT into FB Compared with the reference voltage Vref, whenever the feedback voltage V FB When the voltage is lower than the reference voltage Vref, the on-time generator turns on the high-side power tube M10 for a constant time through control logic and drive to magnetize the inductor L and charge the load capacitor CO. After the constant time is over, the low-side power tube M20 is turned on, the inductor L is demagnetized, and the load capacitor CO is discharged until the feedback voltage V FB Again lower than the reference voltage Vref.

[0046] Figure 2 yes Figure 1 The working timing diagram of the Buck converter is shown in the figure. Figure 2 shows the output voltage V OUT , inductor current I L and the switch node voltage V SW The waveform, such as Figure 2As shown in the figure, when the load capacitor CO is a low ESR capacitor, the system will have a harmonic oscillation problem. After the high-side power tube M10 is turned on for a constant time, it is turned on again after a minimum off time, resulting in an increase in the inductor current ripple and the output voltage ripple. The reason is that the capacitor voltage has a phase lag relative to the inductor current. The inductor current rises immediately when the high-side power tube M10 is turned on, but the capacitor voltage is still decreasing at this time. When the high-side power tube M10 is turned off, the inductor current drops immediately. The capacitor voltage is in the rising stage at this time, but it has not returned to the reference voltage, so it will trigger the next high-side power tube M10 to turn on, causing harmonic oscillation.

[0047] Based on the above reasons, an embodiment of the present invention provides a voltage conversion circuit. Figure 3 is a schematic diagram of a voltage conversion circuit provided by an embodiment of the present invention, with reference to Figure 3 The voltage conversion circuit includes a voltage conversion module 10, a control module 20, a voltage feedback module 30 and a virtual ripple generation module 40; the voltage conversion module 10 includes a main switch tube HS, a freewheeling switch tube LS and a first output storage unit 11, the main switch tube HS and the freewheeling switch tube LS are respectively connected to the first output storage unit 11, the main switch tube HS is used to transmit electric energy to the first output storage unit 11 when it is turned on, and the freewheeling switch tube LS is used to connect the discharge circuit of the first output storage unit 11 when it is turned on; the first output storage unit 11 may include an LC second-order filter, the LC second-order filter includes an inductor L and a first capacitor C1; the first output storage unit 11 1 is connected to the output end of the voltage conversion module 10; the voltage feedback module 30 is respectively connected to the output end of the voltage conversion module 10 and the control module 20, and is used to output a feedback voltage to the control module 20 according to the output voltage of the voltage conversion module 10; the virtual ripple generation module 40 is connected to the control module 20, and the virtual ripple generation module 40 is used to generate a virtual inductor current ripple signal corresponding to the current ripple signal of the inductor L according to the first control signal output by the control module 20; the control module 20 is connected to the main switch tube HS and the freewheeling switch tube LS, and is used to control the conduction time of the main switch tube HS and the freewheeling switch tube LS according to the feedback voltage and the virtual inductor current ripple signal.

[0048] The voltage conversion module 10 may include a DC-DC conversion circuit, which includes a main switch tube HS, a freewheeling switch tube LS, and a first output storage unit 11, wherein the output storage unit includes an inductor L and a first capacitor C1. One of the main switch tube HS and the freewheeling switch tube LS is a high-side power tube, and the other is a low-side power tube. The gate of the main switch tube HS and the gate of the freewheeling switch tube LS are respectively connected to the control module 20. The control module 20 can control the conduction state of the main switch tube HS and the freewheeling switch tube LS by outputting a first control signal, wherein the first control signal includes a control signal output to the main switch tube HS and a control signal output to the freewheeling switch tube LS. Taking the case where the main switch tube HS is a high-side power tube and the freewheeling switch tube LS is a low-side power tube as an example, when the control module 20 controls the main switch tube HS to be turned on, the main switch tube HS transmits electric energy to the first output storage unit 11, magnetizes the inductor L, and charges the first capacitor C1. When the control module 20 controls the freewheeling switch tube LS to turn on, the freewheeling switch tube LS turns on the discharge circuit of the first output storage unit 11, so that the first output storage unit 11 is discharged, that is, the inductor L is demagnetized, and the first capacitor C1 is discharged. The first end of the inductor L can be connected to the main switch tube HS and the freewheeling switch tube LS, the second end of the inductor L is connected to the first end of the first capacitor C1, the second end of the first capacitor C1 can be grounded, and the first end of the first capacitor C1 serves as the output end of the voltage conversion module 10.

[0049] The output end of the voltage conversion module 10 is connected to the voltage feedback module 30, and the voltage feedback module 30 obtains a feedback voltage corresponding to the output voltage according to the output voltage of the voltage conversion module 10, and outputs the feedback voltage to the control module 20. In some embodiments, the voltage feedback module 30 includes a voltage divider circuit, and the voltage feedback module 30 obtains the feedback voltage after dividing the output voltage.

[0050] In this embodiment, the voltage conversion circuit further includes a virtual ripple generation module 40, which generates a virtual inductor current ripple signal corresponding to the inductor current ripple signal according to the first control signal output by the control module 20, and the virtual inductor current ripple signal may be a voltage signal. The virtual inductor current ripple signal is constructed by the virtual ripple generation module 40, and the virtual inductor current ripple signal replaces the ESR information on the first capacitor C1 and is superimposed on the feedback voltage, which is equivalent to constructing a virtual ESR of the first capacitor C1. The control module 20 controls the on-time of the main switch tube HS and the freewheeling switch tube LS according to the virtual inductor current ripple signal and the first control signal outputted at the feedback voltage, thereby improving the harmonic oscillation problem caused by the time lag effect between the inductor current and the output voltage on the first capacitor C1, and improving the stability of the output voltage of the voltage conversion circuit.

[0051] The control module 20 generates a first control signal according to the feedback voltage and the virtual inductor current ripple signal to control the conduction time of the main switch tube HS and the freewheeling switch tube LS. Optionally, in this embodiment, at the initial moment of the voltage conversion circuit working, the control module 20 does not output the first control signal, at which time the feedback voltage and the virtual inductor current ripple signal are both 0, and then the control module 20 can output the initial first control signal according to the feedback voltage and the virtual inductor current ripple are both 0, and then the virtual ripple generation module 40 generates a virtual inductor current ripple signal according to the initial first control signal, and then the control module 20 generates a new first control signal according to the feedback voltage and the virtual inductor current ripple signal to switch the main switch tube HS and the freewheeling switch tube LS, so as to form a closed loop.

[0052] The voltage conversion circuit of this embodiment is provided with a voltage conversion circuit including a voltage conversion module, a control module, a voltage feedback module and a virtual ripple generation module. The control module controls the main switch tube HS and the freewheeling switch tube LS in the voltage conversion module to be turned on alternately to magnetize or demagnetize the inductor, and to charge and discharge the first capacitor. The virtual inductor current ripple signal is constructed by the virtual ripple generation module, which is equivalent to constructing the virtual ESR of the first capacitor. The virtual inductor current ripple signal replaces the ESR information on the first capacitor and is superimposed on the feedback voltage, so that after the feedback voltage is superimposed with the virtual inductor current ripple signal, the phase difference with the inductor current is reduced. The control module controls the conduction time of the main switch tube HS and the freewheeling switch tube LS according to the virtual inductor current ripple signal and the first control signal outputted in the feedback voltage, thereby improving the harmonic oscillation problem caused by the time lag effect between the inductor current and the output voltage on the first capacitor, suppressing the generation of harmonics, and improving the stability of the output voltage of the voltage conversion circuit.

[0053] Figure 4 is a schematic diagram of another voltage conversion circuit provided by an embodiment of the present invention, referring to Figure 4 Optionally, the virtual ripple generating module 40 includes a level shifting circuit 41 and a generating circuit 42. The level shifting circuit 41 is connected to the control module 20 and the generating circuit 42 respectively, and is used to convert the first control signal of the first voltage domain output by the control module 20 to obtain the second control signal of the second voltage domain; the generating circuit 42 is used to generate a virtual inductor current ripple signal corresponding to the current ripple signal of the inductor L according to the second control signal. Among them, Figure 4 The load resistance R is also shown L .

[0054] Specifically, the voltage domain to which the signal output by the control module 20 belongs is the power level voltage domain, while the signal for controlling the first switch tube and the second switch tube is the control level voltage domain, and the voltage domains to which the two belong are different. In this embodiment, by setting the virtual ripple generation module 40 to include a level shift circuit 41, the first control signal of the first voltage domain output by the control module 20 is converted into a second control signal of the second voltage domain, so as to ensure that the voltage input to the generation circuit 42 meets the corresponding voltage requirements, wherein the first voltage domain may be a power level voltage domain, and the second voltage domain may be a control level voltage domain. Among them, the voltage ranges of the first voltage domain and the second voltage domain may be different, and / or the voltage fluctuations of the first voltage domain and the second voltage domain may be different, wherein the power supply fluctuations include but are not limited to voltage noise. Since the level shift circuit 41 performs the conversion from the first voltage domain to the second voltage domain, the generation circuit 42 generates a virtual inductor current ripple signal corresponding to the inductor current ripple signal according to the second control signal of the second voltage domain, so that the generated virtual inductor current ripple signal can be closer to the real inductor current ripple signal, so that it is more conducive to suppressing harmonic generation and improving system stability.

[0055] Figure 5 is a schematic diagram of another voltage conversion circuit provided by an embodiment of the present invention, referring to Figure 5 Optionally, the generating circuit 42 includes a first switch tube M1, a second switch tube M2, a second output storage unit 43, a filtering unit 44 and a subtractor 45; the first end of the second output storage unit 43 is connected to the first switch tube M1 and the second switch tube M2 respectively, the first switch tube M1 and the second switch tube M2 are respectively used to be turned on or off according to the second control signal, the first switch tube M1 is used to transmit electric energy to the second output storage unit 43 when turned on, and the second switch tube M2 is used to connect the discharge circuit of the second output storage unit 43 when turned on; wherein, the first The switch tube M1 has the same on-time period as the main switch tube HS, and the second switch tube M2 has the same on-time period as the freewheeling switch tube LS; the first end of the filter unit 44 is connected to the second end of the second output storage unit 43, and the filter unit 44 is used to filter the first voltage of the second output storage unit 43 to obtain the second voltage; the subtractor 45 is respectively connected to the second end of the second output storage unit 43 and the output end of the filter unit 44, and is used to obtain a voltage ripple signal based on the difference between the first voltage and the second voltage, and the voltage ripple signal is used as a virtual inductor current ripple signal.

[0056] Specifically, the first switch tube M1 and the second switch tube M2 can be turned on or off according to the second control signal. The first switch tube M1 has the same on-time period as the main switch tube HS, and the first switch tube M1 has the same off-time period as the main switch tube HS; the second switch tube M2 has the same on-time period as the freewheeling switch tube LS, and the second switch tube M2 has the same off-time period as the freewheeling switch tube LS. When the main switch tube HS is turned on and the freewheeling switch tube LS is turned off, the inductor L is magnetized, the inductor current rises, and at the same time, the first switch tube M1 is turned on and the second switch tube M2 is turned off, and the power supply voltage VDD charges the second output storage unit 43; when the main switch tube HS is turned off and the freewheeling switch tube LS is turned on, the inductor L is demagnetized, the inductor current decreases, and at the same time, the first switch tube M1 is turned off and the second switch tube M2 is turned on, and the second output storage unit 43 discharges to the ground. Therefore, the voltage information corresponding to the first voltage at the second end of the second output storage unit 43 can be regarded as the inductor current information, and the first voltage at the second end of the second output storage unit 43 is filtered by the filter unit 44 to obtain its DC value (second voltage), and the second voltage can be regarded as the DC component of the inductor current. The virtual inductor current ripple signal can be obtained by subtracting the first voltage and the second voltage using the subtractor 45, and the virtual inductor current ripple signal is used as the inductor current ripple information. Superimposing the inductor current ripple information on the feedback voltage is equivalent to constructing the equivalent series resistance of the load capacitor, which ensures the stability of the system and eliminates harmonic oscillations.

[0057] Continue to refer Figure 5 Optionally, the second output storage unit 43 includes a first RC filter, and the second output storage unit 43 specifically includes a first resistor R1 and a second capacitor C2, the first end of the first resistor R1 is respectively connected to the first switch tube M1 and the second switch tube M2, the second end of the first resistor R1 is connected to the first end of the second capacitor C2, and the second end of the second capacitor C2 is grounded; the first end of the second capacitor C2 serves as the second end of the second output storage unit 43. When the first switch tube M1 is turned on and the second switch tube M2 is turned off, the power supply voltage VDD charges the second capacitor C2 through the first switch tube M1 and the first resistor R1; when the first switch tube M1 is turned off and the second switch tube M2 is turned on, the second capacitor C2 is discharged to the ground through the first resistor R1 and the second capacitor C2.

[0058] Continue to refer Figure 5 Optionally, the filtering unit 44 includes a second RC filter, and the filtering unit 44 specifically includes a second resistor R2 and a third capacitor C3, the first end of the second resistor R2 is connected to the second end of the first resistor R1, the second end of the second resistor R2 is connected to the first end of the third capacitor C3, and the second end of the second capacitor C2 is grounded; the first end of the third capacitor C3 serves as the output end of the filtering unit 44.

[0059] Optionally, the control module 20 includes a first output terminal A1 and a second output terminal A2, the first output terminal A1 is connected to the gate of the main switch tube HS, and the second output terminal A2 is connected to the gate of the freewheeling switch tube LS, the first control signal includes a first sub-control signal output by the control module 20 to the first output terminal A1, and a second sub-control signal output to the second output terminal A2; the first electrode of the main switch tube HS is connected to the second electrode of the freewheeling switch tube LS, the first electrode of the main switch tube HS is also connected to the inductor L, and the second electrode of the main switch tube HS is connected to the input voltage V in , the first electrode of the freewheeling switch tube LS is grounded; the second control signal includes a third sub-control signal and a fourth sub-control signal; the level transfer circuit 41 includes a first transfer unit 411 and a second transfer unit 412, the input end of the first transfer unit 411 is connected to the first output end A1, the output end of the first transfer unit 411 is connected to the gate of the first switch tube M1, and the first transfer unit 411 is used to convert the first sub-control signal of the first voltage domain into a third sub-control signal of the second voltage domain; the first switch tube M1 is used to turn on or off according to the third sub-control signal; the input end of the second transfer unit 412 is connected to the second output end A2, the output end of the second transfer unit 412 is connected to the gate of the second switch tube M2, and the second transfer unit 412 is used to convert the second sub-control signal of the first voltage domain into a fourth sub-control signal of the second voltage domain; the second switch tube M2 is used to turn on or off according to the fourth sub-control signal.

[0060] In some embodiments, the first electrode of the first switch tube M1 is connected to the power supply voltage VDD, the second electrode of the first switch tube M1 is connected to the second electrode of the second switch tube M2, and the first electrode of the second switch tube M2 is grounded; the virtual ripple generating module 40 also includes an inverter 46 and a buffer 47, the input end of the inverter 46 is connected to the first transfer unit 411, and the output end of the inverter 46 is connected to the gate of the first switch tube M1; the input end of the buffer 47 is connected to the second transfer unit 412, and the output end of the buffer 47 is connected to the gate of the second switch tube M2; wherein the first switch tube M1 is a P-type transistor, and the second switch tube M2 is an N-type transistor; the main switch tube HS is an N-type transistor, and the freewheeling switch tube LS is an N-type transistor.

[0061] Specifically, the first switch tube M1 is turned on or off according to the third sub-control signal, specifically, it is turned on or off according to the signal obtained by inverting the third sub-control signal through the inverter 46. The second switch tube M2 is turned on or off according to the fourth sub-control signal, specifically, it is turned on or off according to the signal obtained by buffering the fourth sub-control signal through the buffer 47. Specifically, when the gate is a low-level signal, the P-type transistor is turned on; when the gate is a high-level signal, the N-type transistor is turned on. That is, the effective level (the level that turns on the transistor) corresponding to the first switch tube M1 and the main switch tube HS is different. In this embodiment, by setting the virtual ripple generation module 40 to include an inverter 46, the third control signal after the level transfer of the first transfer unit 411 can be inverted, thereby ensuring that the first switch tube M1 and the main switch tube HS are turned on at the same time. The effective levels corresponding to the second switch tube M2 and the freewheeling switch tube LS are the same, and the effective levels corresponding to the two are both high levels. By setting a buffer 47 between the second transfer unit 412 and the gate of the second switch tube M2, the output and input of the buffer 47 are the same level signals, which can ensure that the conduction periods of the second switch tube M2 and the freewheeling switch tube LS are the same, and by setting the buffer 47, the driving capability of the second switch tube M2 can be enhanced.

[0062] Figure 6 is a schematic diagram of another voltage conversion circuit provided by an embodiment of the present invention, referring to Figure 6 Optionally, the control module 20 includes a logic operation unit 21, a comparator 22, a conduction time generator 23 and a driving unit 24; the logic operation unit 21 is respectively connected to the virtual ripple generation module 40, the voltage feedback module 30 and the comparator 22, and is used to obtain a feedback compensation voltage after performing a logic operation on the virtual inductor current ripple signal and the feedback voltage; the non-inverting input terminal of the comparator 22 is connected to the reference voltage, the inverting input terminal of the comparator 22 is connected to the logic operation unit 21, and the output terminal of the comparator 22 is connected to the conduction time generator 23; the conduction time generator 23 is connected to the driving unit 24, and the conduction time generator 23 is used to generate a driving signal according to the output signal of the comparator 22; the driving unit 24 is used to generate a first control signal according to the driving signal to control the conduction time of the main switch tube HS and the freewheeling switch tube LS.

[0063] Among them, the logic operation unit 21 can perform a logic operation on the virtual inductor current ripple signal and the feedback voltage to obtain the feedback compensation voltage. In some embodiments, the logic operation unit 21 directly performs an AND operation on the virtual inductor current ripple signal and the feedback voltage to obtain the feedback compensation voltage. In other embodiments, the logic operation unit 21 includes a multiplier 211 and an adder 212, the input end of the multiplier 211 is connected to the virtual ripple generation module 40, the output end of the multiplier 211 is connected to the first input end of the adder 212, the second input end of the adder 212 is connected to the output end of the voltage feedback module 30, and the output end of the adder 212 is connected to the inverting input end of the comparator 22. In this way, for first capacitors C1 of different sizes, the weight of the virtual inductor current ripple signal can be adjusted to adapt to it by adjusting the coefficient of the multiplier 211.

[0064] The logic operation unit 21 completes the logic operation of the virtual inductor current ripple signal and the feedback voltage to obtain the feedback compensation voltage. The comparator 22 outputs a corresponding output signal to the conduction time generator 23 according to the magnitude relationship between the feedback compensation voltage and the reference voltage. The conduction time generator 23 generates a driving signal according to the output signal of the comparator 22, such as a pulse width modulation signal. The driving unit 24 generates a first control signal according to the driving signal output by the conduction time generator 23 to control the conduction time of the main switch tube HS and the freewheeling switch tube LS.

[0065] On the basis of the above-mentioned technical solutions, optionally, the voltage conversion circuit includes a chip, and the control module 20 and the virtual ripple generation module 40 are integrated in the chip. In this way, the voltage conversion circuit can construct virtual inductor current ripple information on the chip, and superimpose the ripple information on the feedback voltage. No off-chip compensation network is required, no off-chip passive devices are required, and no integral error will be generated, thereby ensuring the stability of the system. And compared with the solution of constructing an RC compensation network off-chip, the required resistance and capacitance are smaller, which is conducive to chip integration. Optionally, the inductor L, the first capacitor C1, the load resistor RL and the voltage feedback module 30 are arranged outside the chip. Among them, Figure 5 and Figure 6 FIG. 4 exemplarily shows a case where the voltage feedback module 30 includes a voltage divider circuit formed by two resistors.

[0066] The following Figure 6 Taking the voltage conversion circuit shown in the figure as an example, the working process of the entire voltage conversion circuit is described in detail. Figure 7 yes Figure 6 The working timing diagram of the voltage conversion circuit shown in FIG. Figure 7 The switch node voltage V SW , inductor current I L , the first node voltage VN1 and the first voltage V on the second capacitor C2The waveform of the first voltage V on the second capacitor C2 C2 The waveform of FIG. 1 shows a second voltage V on the third capacitor C3. C3 waveform.

[0067] refer to Figure 6 and Figure 7 , the working process of the voltage conversion circuit is as follows:

[0068] When the main switch tube HS is turned on and the freewheeling switch tube LS is turned off, the inductor L is magnetized, the inductor current increases, and at the same time, the first switch tube M1 is turned on and the second switch tube M2 is turned off, and the power supply voltage VDD charges the second capacitor C2 through the first switch tube M1 and the first resistor R1; when the main switch tube HS is turned off and the freewheeling switch tube LS is turned on, the inductor L is demagnetized, the inductor current decreases, and at the same time, the first switch tube M1 is turned off and the second switch tube M2 is turned on, and the second capacitor C2 is discharged to the ground through the first resistor R1 and the second switch tube M2. Therefore, the voltage information corresponding to the first voltage on the second capacitor C2 can be regarded as the inductor current information, and then the first voltage V on the second capacitor C2 is filtered by the filtering unit 44 formed by the second resistor R2 and the third capacitor C3. C2 The DC value (the second voltage V C3 ), the second voltage V C3 The first voltage and the second voltage are subtracted by the subtractor 45 to obtain a virtual inductor current ripple signal, which is used as the inductor current ripple information.

[0069] Specifically, Figure 6 and Figure 7 As shown, when the output voltage is lower than the rated value, the system enters the first stage t1, the main switch tube HS is turned on, the freewheeling switch tube LS is turned off, the inductor current increases, and the first capacitor C1 is charged; the first switch tube M1 is turned on, the second switch tube M2 is turned off, and the second capacitor C2 is charged. After the on-time ends, the system enters the second stage t2, the main switch tube HS is turned off, the freewheeling switch tube LS is turned on, the inductor current decreases, and the first capacitor C1 is discharged; the first switch tube M1 is turned off, the second switch tube M2 is turned on, and the second capacitor C2 is discharged. The second voltage on the third capacitor C3 is the DC value of the first node voltage VN1, so the second voltage Where V OUT is the output voltage of the voltage conversion circuit, V in is the input voltage of the voltage conversion circuit, and VDD is the power supply voltage. Under the condition that the system switching period T is much smaller than the product of the resistance value of the first resistor R1 and the second capacitor C2, the charging slope of the second capacitor C2 is Where R 10 represents the resistance value of the first resistor R1, C 20represents the capacitance value of the second capacitor C2 and the discharge slope of the second capacitor C2 The first voltage V on the second capacitor C2 C2 and the second voltage V on the third capacitor C3 C3 The difference is superimposed on the feedback voltage V FB The voltage is then compared with the on-chip reference voltage Vref to determine whether to enter the first stage t1 again.

[0070] An embodiment of the present invention further provides a switching power supply, which includes the voltage conversion circuit of any of the above embodiments of the present invention.

[0071] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0072] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A voltage conversion circuit, characterized in that: include: Voltage conversion module, control module, voltage feedback module and virtual ripple generation module; The voltage conversion module includes a main switch tube, a freewheeling switch tube and a first output storage unit, the main switch tube and the freewheeling switch tube are respectively connected to the first output storage unit, the main switch tube is used to transmit electric energy to the first output storage unit when it is turned on, and the freewheeling switch tube is used to connect the discharge circuit of the first output storage unit when it is turned on; the first output storage unit includes an inductor and a first capacitor; the first output storage unit is connected to the output end of the voltage conversion module; The voltage feedback module is connected to the output end of the voltage conversion module and the control module respectively, and is used to output a feedback voltage to the control module according to the output voltage of the voltage conversion module; The virtual ripple generating module is connected to the control module, and the virtual ripple generating module is used to generate a virtual inductor current ripple signal corresponding to the current ripple signal of the inductor according to the first control signal output by the control module; The control module is connected to the main switch tube and the freewheeling switch tube, and is used to control the conduction time of the main switch tube and the freewheeling switch tube according to the feedback voltage and the virtual inductor current ripple signal.

2. The voltage conversion circuit according to claim 1, characterized in that: The virtual ripple generating module comprises a level transfer circuit and a generating circuit, wherein the level transfer circuit is connected to the control module and the generating circuit respectively, and is used for converting a first control signal in a first voltage domain output by the control module into a second control signal in a second voltage domain; The generating circuit is used for generating a virtual inductor current ripple signal corresponding to the current ripple signal of the inductor according to the second control signal.

3. The voltage conversion circuit according to claim 2, characterized in that: The generating circuit includes a first switch tube, a second switch tube, a second output storage unit, a filtering unit and a subtractor; The first end of the second output storage unit is connected to the first switch tube and the second switch tube respectively, the first switch tube and the second switch tube are respectively used to be turned on or off according to the second control signal, the first switch tube is used to transmit electric energy to the second output storage unit when turned on, and the second switch tube is used to connect the discharge circuit of the second output storage unit when turned on; wherein the first switch tube has the same conduction period as the main switch tube, and the second switch tube has the same conduction period as the freewheeling switch tube; The first end of the filtering unit is connected to the second end of the second output storage unit, and the filtering unit is used to filter the first voltage of the second output storage unit to obtain a second voltage; The subtractor is connected to the second end of the second output storage unit and the output end of the filter unit respectively, and is used to obtain a voltage ripple signal according to the difference between the first voltage and the second voltage, and the voltage ripple signal is used as the virtual inductor current ripple signal.

4. The voltage conversion circuit according to claim 3, characterized in that: The second output storage unit includes a first resistor and a second capacitor, wherein the first end of the first resistor is connected to the first switch tube and the second switch tube respectively, the second end of the first resistor is connected to the first end of the second capacitor, and the second end of the second capacitor is grounded; the first end of the second capacitor serves as the second end of the second output storage unit; The filtering unit includes a second resistor and a third capacitor, the first end of the second resistor is connected to the second end of the first resistor, the second end of the second resistor is connected to the first end of the third capacitor, and the second end of the second capacitor is grounded; the first end of the third capacitor serves as the output end of the filtering unit.

5. The voltage conversion circuit according to claim 3, characterized in that: The control module includes a first output end and a second output end, the first output end is connected to the gate of the main switch tube, the second output end is connected to the gate of the freewheeling switch tube, the first control signal includes a first sub-control signal output by the control module to the first output end, and a second sub-control signal output to the second output end; the first pole of the main switch tube is connected to the second pole of the freewheeling switch tube, the first pole of the main switch tube is also connected to the inductor, the second pole of the main switch tube is connected to the input voltage, and the first pole of the freewheeling switch tube is grounded; The second control signal includes a third sub-control signal and a fourth sub-control signal; The level transfer circuit comprises a first transfer unit and a second transfer unit, wherein the input end of the first transfer unit is connected to the first output end, the output end of the first transfer unit is connected to the gate of the first switch tube, the first transfer unit is used to convert the first sub-control signal of the first voltage domain into a third sub-control signal of the second voltage domain; the first switch tube is used to be turned on or off according to the third sub-control signal; The input end of the second transfer unit is connected to the second output end, the output end of the second transfer unit is connected to the gate of the second switch tube, and the second transfer unit is used to convert the second sub-control signal of the first voltage domain into a fourth sub-control signal of the second voltage domain; the second switch tube is used to turn on or off according to the fourth sub-control signal.

6. The voltage conversion circuit according to claim 5, characterized in that: A first electrode of the first switch tube is connected to a power supply voltage, a second electrode of the first switch tube is connected to a second electrode of the second switch tube, and a first electrode of the second switch tube is grounded; The virtual ripple generating module further includes an inverter and a buffer, wherein the input end of the inverter is connected to the first transfer unit, and the output end of the inverter is connected to the gate of the first switch tube; The input end of the buffer is connected to the second transfer unit, and the output end of the buffer is connected to the gate of the second switch tube; Among them, the first switch tube is a P-type transistor, the second switch tube is an N-type transistor; the main switch tube is an N-type transistor, and the freewheeling switch tube is an N-type transistor.

7. The voltage conversion circuit according to claim 1, characterized in that: The control module includes a logic operation unit, a comparator, a conduction time generator and a driving unit; The logic operation unit is connected to the virtual ripple generation module, the voltage feedback module and the comparator respectively, and is used to obtain a feedback compensation voltage after performing a logic operation on the virtual inductor current ripple signal and the feedback voltage; The non-inverting input terminal of the comparator is connected to the reference voltage, the inverting input terminal of the comparator is connected to the logic operation unit, and the output terminal of the comparator is connected to the conduction time generator; The on-time generator is connected to the driving unit, and is used to generate a driving signal according to the output signal of the comparator; the driving unit is used to generate the first control signal according to the driving signal to control the on-time of the main switch tube and the freewheeling switch tube.

8. The voltage conversion circuit according to claim 7, characterized in that: The logic operation unit includes a multiplier and an adder, the input end of the multiplier is connected to the virtual ripple generation module, the output end of the multiplier is connected to the first input end of the adder, the second input end of the adder is connected to the output end of the voltage feedback module, and the output end of the adder is connected to the inverting input end of the comparator.

9. The voltage conversion circuit according to claim 1, characterized in that: A chip is included, in which the control module and the virtual ripple generating module are integrated.

10. A switching power supply, characterized in that: The invention comprises the voltage conversion circuit as described in any one of claims 1 to 9.

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