CN113644822B - Power supply device, switching power supply conversion circuit and control method thereof - Google Patents

Power supply device, switching power supply conversion circuit and control method thereof Download PDF

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Publication number
CN113644822B
CN113644822B CN202111206963.3A CN202111206963A CN113644822B CN 113644822 B CN113644822 B CN 113644822B CN 202111206963 A CN202111206963 A CN 202111206963A CN 113644822 B CN113644822 B CN 113644822B
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circuit
bandwidth
switching
switching frequency
frequency
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CN113644822A (en
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黄东栩
朱炜礼
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Guangdong Saiwei Electronics Co ltd
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Guangdong Saiwei Electronics Co ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/14—Arrangements for reducing ripples from dc input or output
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/44—Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load

Abstract

The application relates to the field of switching power supply circuits, and discloses a power supply device, a switching power supply conversion circuit and a control method. The switching power supply conversion circuit comprises a switching circuit, a filter circuit and a bandwidth adjustable error circuit. The first end of the switch circuit is connected with a power supply; the first end of the filter circuit is connected with the third end of the switch circuit, and the second end of the filter circuit is connected with a load; the first end of the bandwidth adjustable error circuit is connected with the second end of the filter circuit, and the second end of the bandwidth adjustable error circuit is connected with the second end of the switch circuit; the bandwidth adjustable error circuit receives the current output voltage, and obtains switching frequency based on the current output voltage, wherein the switching frequency is used for controlling the switching circuit to work; the bandwidth adjustable error circuit acquires the current switching frequency, adjusts the bandwidth of the conversion circuit according to the current switching frequency, and the adjusted bandwidth is smaller than the current switching frequency. When the output is small, the switching ripple waves on the output voltage cannot be amplified, the system stability is facilitated, the power supply control from high output to low output is realized by using one circuit, and the complexity of the system and the chip cost are reduced.

Description

Power supply device, switching power supply conversion circuit and control method thereof
Technical Field
The present disclosure relates to switching power supplies, and particularly to a power supply device, a switching power supply conversion circuit and a control method thereof.
Background
With the development of science and technology, people have higher and higher requirements on electronic products such as mobile phones and flat panels. Various electronic products on the market today also have high demands on the power supply system. Not only is a fast response speed required, but also stability, conversion efficiency and cost are increasingly required. Among them, the switching power supply conversion circuit plays an indispensable role. Switching power conversion circuits are generally designed with a control loop to ensure stable output. However, depending on the load, the use environment, and the like, it is difficult for a single control circuit to cope with various demands. Especially, the influence of the switching ripple on the output is large when the load is low, and the control by using a plurality of control loops greatly increases the complexity of the control system and the chip cost.
Disclosure of Invention
In order to solve the above problem, the present application provides a switching power supply converting circuit, which includes a switching circuit, a filter circuit, and a bandwidth-adjustable error circuit. The first end of the switch circuit is connected with a power supply; the first end of the filter circuit is connected with the third end of the switch circuit, and the second end of the filter circuit is connected with the load; the first end of the bandwidth adjustable error circuit is connected with the second end of the filter circuit, and the second end of the bandwidth adjustable error circuit is connected with the second end of the switch circuit; the bandwidth-adjustable error circuit receives the current output voltage from the second end of the filter circuit, and obtains switching frequency based on the current output voltage, wherein the switching frequency is used for controlling the switching circuit to work; the bandwidth adjustable error circuit acquires the current switching frequency from the switching circuit, and adjusts the bandwidth of the conversion circuit according to the current switching frequency, wherein the adjusted bandwidth of the conversion circuit is smaller than the current switching frequency.
Optionally, the bandwidth of the adjusted conversion circuit is less than one fifth of the current switching frequency, the bandwidth-adjustable error circuit adjusts the sampling frequency based on the current switching frequency, and adjusts the bandwidth of the bandwidth-adjustable error circuit based on the adjusted sampling frequency, so as to adjust the bandwidth of the conversion circuit based on the current switching frequency; the ratio between the sampling frequency and the bandwidth of the bandwidth adjustable error circuit is equal to the ratio between the adjusted sampling frequency and the bandwidth of the adjusted bandwidth adjustable error circuit.
Optionally, the bandwidth adjustable error circuit comprises a comparator and a bandwidth adjustable error amplifier. The first input end of the bandwidth adjustable error amplifier receives the reference voltage, the second input end of the bandwidth adjustable error amplifier is connected with the second end of the filter circuit, and the bandwidth adjustable error amplifier further receives the current switching frequency of the switch circuit; the sampling frequency is the frequency of sampling output voltage of the bandwidth-adjustable error amplifier; the first input end of the comparator is connected with the second end of the filter circuit, the second input end of the comparator is connected with the output end of the bandwidth-adjustable error amplifier, the third input end of the comparator receives a first voltage, and the output end of the comparator is connected with the second end of the switch circuit and used for outputting switching frequency.
Optionally, the bandwidth adjustable error circuit further comprises a time calculation circuit; the first end of the time calculation circuit is connected with the output end of the comparator, and the second end of the time calculation circuit is connected with the second end of the switch circuit; the time calculation circuit is used for adjusting the conduction time of each switching tube in the switching circuit to generate switching frequency.
Optionally, the switching circuit includes a switching driver, a first switching tube and a second switching tube; the first end of the first switch tube receives power supply voltage, and the second end of the first switch tube is connected with the first end of the filter circuit; the first end of the second switching tube is grounded, and the second end of the second switching tube is connected with the first end of the filter circuit; the first end of the switch driver is connected with the output end of the bandwidth-adjustable error circuit, the second end of the switch driver is connected with the control end of the first switch tube, and the third end of the switch driver is connected with the control end of the second switch tube so as to control the conduction of the first switch tube and the second switch tube based on the switching frequency.
Optionally, the filter circuit comprises an inductor and a capacitor; the first end of the inductor is connected with the second end of the first switching tube and the second end of the second switching tube, and the second end of the inductor is connected with the load of the conversion circuit and the first end of the bandwidth adjustable error circuit; the first end of the capacitor is connected with the second end of the inductor, and the second end of the capacitor is grounded.
Optionally, the bandwidth adjustable error circuit receives a current switching frequency of the switching circuit from the first terminal of the inductor.
In order to solve the above problem, the present application further provides a control method of a switching power supply conversion circuit, which is applied to the switching power supply conversion circuit, and includes the following steps: receiving a current output voltage from the filter circuit; obtaining a switching frequency based on the current output voltage; acquiring the current switching frequency; and adjusting the bandwidth of the conversion circuit according to the current switching frequency, wherein the adjusted bandwidth of the conversion circuit is smaller than the current switching frequency.
Optionally, adjusting the bandwidth of the conversion circuit according to the current switching frequency, where the step of adjusting the bandwidth of the conversion circuit to be smaller than the current switching frequency includes: adjusting the sampling frequency based on the current switching frequency; adjusting the bandwidth of the bandwidth adjustable error circuit based on the adjusted sampling frequency to realize the adjustment of the bandwidth of the conversion circuit based on the current switching frequency; the bandwidth of the adjusted conversion circuit is less than one fifth of the current switching frequency, and the ratio of the sampling frequency to the bandwidth of the bandwidth-adjustable error circuit is equal to the ratio of the adjusted sampling frequency to the bandwidth of the bandwidth-adjustable error circuit.
In order to solve the above problem, the present application further provides a power supply apparatus including the switching power supply conversion circuit.
The switching power supply conversion circuit that this application supplied includes the adjustable error circuit of bandwidth, the adjustable error circuit of bandwidth can sample conversion circuit's switching frequency, and adjust sampling frequency according to switching frequency, make sampling frequency be close to switching frequency all the time, make the power of load, switching ripple also can not be enlargied when output power is less promptly, be favorable to circuit system's stability, and realized the power loop control from high output to the whole output range of low output with same circuit, control system's complexity and chip cost have been reduced, make conversion circuit's output voltage always remain stable under arbitrary output current.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Wherein:
fig. 1 is a circuit diagram of a switching power supply conversion circuit according to a first embodiment of the present application;
FIG. 2 is a circuit diagram of a switching power converter circuit according to a second embodiment of the present application;
FIG. 3 is a circuit diagram of a switching power converter circuit according to a third embodiment of the present application;
FIG. 4 is a flowchart illustrating an embodiment of a control method for a switching power converter circuit according to the present application;
fig. 5 is a flowchart of another embodiment of a control method of a switching power converter circuit according to the present application.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the present application are described in detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of the application and are not limiting of the application. It should be further noted that, for the convenience of description, only some of the structures related to the present application are shown in the drawings, not all of the structures. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The terms "first", "second", etc. in this application are used to distinguish between different objects and not to describe a particular order. Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.
Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.
Fig. 1 is a circuit diagram of a switching power supply conversion circuit according to a first embodiment of the present application.
The present application provides a switching power supply converting circuit 10, as shown in fig. 1, the switching power supply converting circuit 10 includes a switching circuit 11, a filter circuit 12, and a bandwidth adjustable error circuit 13.
The first terminal of the switch circuit 11 is connected to the power supply 30, the power supply 30 may be a dc power supply, and the first terminal of the switch circuit 11 may receive a power supply voltage (VIN in fig. 1) from the power supply 30.
The first terminal of the filter circuit 12 is connected to the third terminal of the switch circuit 11, the second terminal of the filter circuit 12 is connected to the load 20, and the output voltage (e.g., VOUT in fig. 1) is output through the second terminal of the filter circuit 12.
Alternatively, the present embodiment uses the filter circuit 12 as an output circuit, and the switch circuit 11 controls the on/off between the filter circuit 12 and the power supply 30.
A first terminal of the bandwidth adjustable error circuit 13 is connected to the second terminal of the filter circuit 12, and a second terminal of the bandwidth adjustable error circuit 13 is connected to the second terminal of the switch circuit 11. The second terminal of the switch circuit 11 is a control terminal of the switch circuit 11, and the switch circuit 11 controls the on/off between the power supply 30 and the filter circuit 12 through the input of the control terminal.
The bandwidth adjustable error circuit 13 receives the current output voltage VOUT from the second end of the filter circuit 12, and obtains a switching frequency based on the current output voltage VOUT, where the switching frequency is used to control the operation of the switch circuit 11; the bandwidth adjustable error circuit 13 obtains the current switching frequency from the switching circuit 11, and adjusts the bandwidth of the switching power supply converting circuit 10 according to the current switching frequency, where the bandwidth of the switching power supply converting circuit 10 after adjustment is smaller than the current switching frequency.
Alternatively, the adjustable bandwidth error circuit 13 receives the output voltage VOUT from the second terminal of the filter circuit 12 in real time, adjusts the switching frequency of the switch circuit 11 based on the output voltage VOUT, and the adjustable bandwidth error circuit 13 adjusts the sampling frequency based on the switching frequency so that the adjusted sampling frequency is close to the switching frequency, thereby adjusting the bandwidth of the adjustable bandwidth error circuit 13 to make the adjusted bandwidth of the circuit system smaller than the switching frequency. The circuit system bandwidth is the bandwidth of the switching power converter circuit 10. The switching frequency of the switching circuit 11 controls the duty cycle of the switching circuit 11, thereby controlling the output power and the output voltage VOUT of the switching power converter circuit 10.
The adjustable bandwidth error circuit 13 controls the switch circuit 11 by adjusting the switching frequency after sampling the output voltage VOUT through feedback control, so that the output voltage VOUT can be kept stable. Receiving the switching frequency from the switching circuit 11, the sampling frequency may be adjusted in the range of 3.125kHz-400kHz so that the adjusted sampling frequency approaches the switching frequency, thereby adjusting the bandwidth of the error circuit so that the adjusted bandwidth of the circuitry is less than the switching frequency, so that the bandwidth adjustable error circuit 13 may cause a change in state on the control loop of the circuitry only if there are a number of consecutive periodic changes on the load 20 during feedback control.
Alternatively, the switching power supply conversion circuit 10 in this embodiment is a switching power supply conversion circuit 10 with a constant on-time or a constant off-time. For example, when the on-time is constant, the load 20 changes, the circuit operates in a continuous on-mode, the on-time and the off-time are substantially constant, and the switching frequency is also substantially constant. If the circuit is operated in the discontinuous conduction mode, the turn-off time can be changed and the switching frequency is changed correspondingly in order to keep the output voltage VOUT constant. It is also possible that both the on-time and the off-time are changed, but according to a certain relationship, so that the switching frequency is also changed.
One embodiment of the switching power converter circuit 10 of the present application is a switching power converter circuit 10 with a constant on-time. When the load 20 is relatively powerful, the circuit operates in a continuous conduction mode. When the load 20 is powered down, the circuit may enter a discontinuous conduction mode in which each conduction cycle of the switching circuit 10 outputs a fixed amount of power to the output terminal. As the power of the load 20 decreases, the switching frequency also decreases. When the switching frequency is smaller than the loop bandwidth of the control loop, the control loop amplifies the switching ripple waves in the circuit; the control loop in this embodiment is the bandwidth adjustable error circuit 13. The switching ripple is an alternating current signal on the output voltage VOUT whose frequency is equivalent to the switching frequency. The loop bandwidth is the frequency corresponding to the control loop gain of 1. When the switching frequency is smaller than the loop bandwidth, the control loop reacts quickly, the switching ripple waves can be amplified, and the stability of the circuit is not facilitated.
Fig. 2 is a circuit diagram of a switching power supply conversion circuit according to a second embodiment of the present application.
As shown in fig. 2, the error amplifying circuit 14 may be composed of an integrator 141 and an operational amplifier 142, and can amplify the deviation of the output voltage VOUT to control the stability of the output voltage VOUT, but the bandwidth of the error amplifying circuit 14 is fixed, resulting in a fixed bandwidth of the whole system control loop. When the load 20 is low power such that the switching frequency may be less than the system control loop bandwidth.
While the bandwidth of the bandwidth adjustable error circuit 13 in fig. 1 is adjustable, the sampling frequency is adjusted based on the switching frequency, so as to adjust the bandwidth of the bandwidth adjustable error circuit 13. Therefore, the bandwidth of the circuit system can be ensured to be always smaller than the switching frequency, and the switching ripple in the conversion circuit 10 can not be amplified by the bandwidth-adjustable error circuit 13, which is beneficial to the stability of the circuit.
Optionally, the bandwidth of the adjusted switching power supply conversion circuit 10 is less than one fifth of the current switching frequency, the bandwidth-adjustable error circuit 13 adjusts the sampling frequency based on the current switching frequency, and adjusts the bandwidth of the bandwidth-adjustable error circuit 13 based on the adjusted sampling frequency, so as to adjust the bandwidth of the switching power supply conversion circuit 10 based on the current switching frequency; the ratio between the sampling frequency and the bandwidth of the bandwidth adjustable error circuit is equal to the ratio between the adjusted sampling frequency and the bandwidth of the adjusted bandwidth adjustable error circuit 13. The bandwidth of the bandwidth adjustable error circuit 13 and the bandwidth of the switching power supply conversion circuit 10 have a variation trend of increasing and decreasing.
Optionally, the adjusted bandwidth of the circuit system is less than one fifth of the switching frequency, and the bandwidth adjustable error circuit 13 receives the current switching frequency from the switching circuit 11, and obtains the sampling frequency based on the current switching frequency, so as to adjust the bandwidth of the bandwidth adjustable error circuit 13, so that the bandwidth of the circuit system is adjusted accordingly.
According to the system stability principle, when the bandwidth of the circuit system is smaller than the switching frequency, the switching ripple wave is attenuated in the circuit system, and the attenuation amplitude is inversely proportional to the gain of the circuit system at the switching frequency. In practical use, however, the bandwidth of the circuitry must be much less than half the switching frequency so that the amplitude of the switching ripple is sufficiently attenuated. The switching frequency in this embodiment is the switching frequency of the switching power converter circuit 10. The adjustable bandwidth error circuit 13 adjusts the sampling frequency according to the switching frequency, so that the bandwidth of the adjustable bandwidth error circuit 13 is adjusted to make the adjusted bandwidth of the circuit system less than one fifth of the switching frequency, and the stability of the system is effectively ensured. When the power of the load 20 becomes smaller, the switching frequency becomes smaller, but the bandwidth of the adjustable bandwidth error circuit 13 also becomes smaller accordingly, and the switching ripple is not amplified by the adjustable bandwidth error circuit 13.
As shown in fig. 1, the bandwidth adjustable error circuit 13 includes a comparator 131 and a bandwidth adjustable error amplifier 132. A first input terminal of the bandwidth adjustable error amplifier 132 receives a reference voltage (for example, VREF in fig. 3), a second terminal of the bandwidth adjustable error amplifier 132 is connected to a second terminal of the filter circuit 12, and the bandwidth adjustable error amplifier 132 further receives the current switching frequency of the switch circuit 11. A first input terminal of the comparator 131 is connected to the second terminal of the filter circuit 12, a second input terminal of the comparator 131 is connected to the output terminal of the bandwidth-adjustable error amplifier 132, a third input terminal of the comparator 131 receives the first voltage (e.g., Vc in fig. 3), and an output terminal of the comparator 131 is connected to the second terminal of the switch circuit 11 for outputting the switching frequency.
The bandwidth of the adjustable bandwidth error amplifier 132 is adjustable, and the adjustable bandwidth error amplifier 132 obtains the switching frequency and adjusts the sampling frequency according to the switching frequency, so as to adjust the bandwidth of the adjustable bandwidth error circuit 13, so that the adjusted bandwidth of the circuit system is always smaller than one fifth of the switching frequency. Therefore, when the converting circuit 10 outputs an output current of any magnitude, the switching ripple on the output voltage VOUT of the converting circuit 10 passes through the adjustable bandwidth error circuit, and the signal amplitude can be always attenuated, so as to keep the output voltage VOUT always stable at any output current. Of course the output current must be within the operating range.
The bandwidth-adjustable error circuit 13 samples the output voltage VOUT from the second end of the filter circuit 12, compares the output voltage VOUT with the reference voltage VREF, amplifies the difference of the comparison to obtain an amplified error voltage, and outputs the amplified error voltage to a circuit of the next link, i.e., the comparator 131.
The comparator 131 samples the output voltage VOUT and receives the amplified error voltage from the bandwidth adjustable error amplifier 132. When the output voltage VOUT is smaller than the sum of the amplified error voltage and the first voltage Vc, the output of the comparator 131 becomes logic high, the switching circuit starts a new conversion period, the switching circuit 11 starts to be turned on, and after a preset on time, the switching circuit 11 starts to be turned off and enters an off time. The comparator 131 and the bandwidth adjustable error amplifier 132 both need to sample the output voltage VOUT, and it can be seen that the switching circuit 10 can be a switching power supply switching circuit with constant on-time in dual voltage control mode.
Optionally, the first voltage Vc is a sawtooth wave to ensure that the control loop does not generate subharmonic oscillation.
Optionally, the bandwidth adjustable error circuit 13 further includes a time calculation circuit 133, a first terminal of the time calculation circuit 133 is connected to the output terminal of the comparator 131, and a second terminal of the time calculation circuit 133 is connected to the second terminal of the switch circuit 11. The time calculation circuit 133 is configured to adjust the on-time and the off-time of each switching tube in the switching circuit 11 based on the switching frequency. The time calculation circuit 133 controls the switching frequency by controlling the on-time and off-time of each switching tube in the switching circuit 11. Here, the time calculation circuit 133 may adjust the on time and the off time of each switching tube in the switching circuit 11 based on the output level of the comparator 131.
Alternatively, the second terminal of the time calculation circuit 133 outputs a square wave with a high level for a fixed time.
Fig. 3 is a circuit diagram of a switching power supply converting circuit according to a third embodiment of the present application.
As shown in fig. 3, the switching circuit 11 includes a switching driver 113, a first switching tube 111, and a second switching tube 112. A first terminal of the first switch tube 111 receives the supply voltage VIN, and a second terminal of the first switch tube 111 is connected to the first terminal of the filter circuit 12. A first terminal of the second switch tube 112 is grounded, and a second terminal of the second switch tube 112 is connected to the first terminal of the filter circuit 12.
A first terminal of the switch driver 113 is connected to the output terminal of the adjustable bandwidth error circuit 13, a second terminal of the switch driver 113 is connected to the control terminal of the first switch tube 111, and a third terminal of the switch driver 113 is connected to the control terminal of the second switch tube 112, so as to control the conduction of the first switch tube 111 and the second switch tube 112 based on the switching frequency. Optionally, the switch driver 113 provides the first switch tube 111 and the second switch tube 112 with the voltage required for turning on or off.
Optionally, during the on-time of each cycle of the circuit, the first switch tube 111 is turned on, the second switch tube 112 is turned off, and the filter circuit 12 is turned on with respect to the power supply 30, stores energy in the inductor 122 and supplies current to the load 20. In the off time of each cycle of the circuit, the first switch tube 111 is turned off, the second switch tube 112 is turned on, the first end of the filter circuit 12 becomes grounded, and the stored energy on the inductor 122 is released to the load 20.
Specifically, the filter circuit 12 includes a capacitor 121 and an inductor 122, a first terminal of the inductor 122 is connected to the second terminal of the first switch tube 111 and the second terminal of the second switch tube 112, and a second terminal of the inductor 122 is connected to the load 20 and a first terminal of the bandwidth adjustable error circuit 13, that is, a second terminal of the bandwidth adjustable error amplifier 132. A first terminal of the capacitor 121 is connected to the second terminal of the inductor 122, and a second terminal of the capacitor 121 is grounded. The filter circuit 12, which is composed of the capacitor 121 and the inductor 122, has a filtering function, and can reduce noise in the output.
There are various locations where the bandwidth adjustable error circuit 13 receives the current switching frequency. The bandwidth adjustable error circuit 13 may receive the switching frequency from the first terminal of the inductance 122. The first terminal of the inductor 122 is also the third terminal of the switching circuit 11. Specifically, the voltage at the first end of the receiving inductor 122 may be received, and the current at the first end of the receiving inductor 122 may also be received.
Optionally, the bandwidth adjustable error circuit 13 may receive the switching frequency from the second end of the first switch tube 111.
One implementation of the switching power converter circuit 10 in the above embodiment is that the on-time in the circuit is constant. For the switching power supply switching circuit 10 with constant on-time, when the power of the load 20 changes, if the circuit works in the continuous on-mode, the circuit rapidly changes the valley value of the current of the inductor 122 through negative feedback, the on-time and the off-time are basically unchanged, and the switching frequency is also basically unchanged. If the circuit works in the discontinuous conduction mode, the turn-off time is changed, so that the output voltage VOUT is kept stable. The switching frequency changes accordingly.
When the power of the load 20 is relatively large, the switching period is relatively short and the switching frequency is relatively high. For example, when the switching frequency is much larger than five times the bandwidth of the circuit system, the amplitude of the switching ripple pair is greatly attenuated after passing through the adjustable-bandwidth error circuit 13. At this time, the set sampling frequency may not be changed, and the initial value of the sampling frequency may be the optimal value when the circuit operates at the rated power. Of course, the circuit may also change the sampling frequency according to some algorithm at all times, so that the circuit system bandwidth may also be kept below one fifth of the switching frequency.
When the load 20 is powered down, the switching period becomes longer and the switching frequency becomes smaller, which is close to five times the bandwidth of the circuitry. For example, when the load 20 changes so that the switching frequency is equal to or less than five times the bandwidth of the circuit system, the circuit adjusts the sampling frequency so that the adjusted bandwidth of the circuit system is less than one fifth of the switching frequency, that is, the switching frequency is greater than five times the bandwidth of the circuit system, so that the whole circuit system is stable and the influence of the switching ripple is not amplified.
Therefore, the switching power supply switching circuit 10 in this embodiment can implement circuit control at the time of high output and low output through one bandwidth-adjustable error circuit 13, and adopt a single control mode within the full output current range, so that it is possible to implement circuit control with high accuracy and fast response without switching a control circuit, simplify the control mode, and avoid mode switching management. And simultaneously, the chip area and the power consumption can be reduced.
The present application further provides a control method of the switching power converter circuit 10, which is applied to the switching power converter circuit 10 according to any one of fig. 1 and fig. 3.
Fig. 4 is a flowchart illustrating an embodiment of a control method of a switching power converter circuit according to the present application.
As shown in fig. 4, the control method includes:
step S11: an output voltage is received from the filter circuit.
In this step, the switching power supply converting circuit 10 receives the output voltage VOUT from the filter circuit 12 in real time.
Optionally, receiving the output voltage VOUT from the filter circuit 12 in step S11 may further include step S111:
step S111: the current switching frequency is received from the switching circuit and the sampling frequency is adjusted based on the current switching frequency.
The received switching frequency and the resulting sampling frequency are both needed for subsequent control procedures.
Step S12: the switching frequency of the switching circuit is adjusted based on the output voltage.
When the output voltage VOUT varies, the switching frequency changes accordingly. For example, when the load 20 has a large power and the output voltage VOUT is greater than the reference voltage VREF, the off time is lengthened by the feedback control, that is, the switching frequency is decreased, so that the output voltage VOUT is decreased; when the power of the load 20 is small and the output voltage VOUT is smaller than the reference voltage VREF, the off time is reduced by the feedback control, that is, the switching frequency is increased, so that the output voltage VOUT is increased. Thereby keeping the output voltage VOUT stable.
Step S13: and adjusting the sampling frequency based on the switching frequency, thereby adjusting the bandwidth of the bandwidth-adjustable error circuit to enable the adjusted bandwidth of the circuit system to be smaller than the switching frequency.
The bandwidth of the circuit system is always smaller than the switching frequency, which is beneficial to the stability of the circuit system. Under the condition of high output or low output, the circuit can be always free from the influence of switching ripples, the mode is single, the control mode is simplified, the mode switching management is avoided, and the chip area and the power consumption can be reduced.
Alternatively, step S13 may also be: the sampling frequency is adjusted based on the switching frequency, thereby adjusting the bandwidth of the bandwidth adjustable error circuit 13 such that the adjusted circuitry bandwidth is less than one fifth of the switching frequency. The reason for making the circuitry bandwidth less than one fifth of the switching frequency is not described here in detail.
Alternatively, in the case of high output, the switching frequency itself is much greater than five times the bandwidth of the circuitry. At this time, the influence of the switching ripple on the output voltage VOUT is small, and the stability of the circuit is not influenced. Therefore, the switching frequency can be maintained at the already set optimum value. Only when the switching frequency is less than five times the bandwidth of the circuitry, the bandwidth of the circuitry is adjusted to less than one fifth of the switching frequency. Therefore, the process of adjusting the sampling frequency of the circuit at high output can be simplified, the control process is simplified, and the energy consumption is saved.
Fig. 5 is a schematic flowchart of another embodiment of a control method of a switching power converter circuit according to the present application.
The application provides a control method of a switching power supply conversion circuit, which is applied to the switching power supply conversion circuit. As shown in fig. 5, the method comprises the steps of:
s21: the present output voltage is received from the filter circuit.
In this step, the switching power supply converting circuit 10 receives the output voltage VOUT from the filter circuit 12 in real time.
S22: the switching frequency is derived based on the present output voltage.
The output voltage VOUT determines the switching frequency of the switching circuit 11.
S23: and acquiring the current switching frequency.
The bandwidth adjustable error circuit 13 obtains the switching frequency of the switching circuit 11 for later use.
S24: and adjusting the bandwidth of the conversion circuit according to the current switching frequency, wherein the adjusted bandwidth of the conversion circuit is smaller than the current switching frequency.
The bandwidth of the circuit system is always smaller than the switching frequency, which is beneficial to the stability of the circuit system. Under the condition of high output or low output, the circuit can be always free from the influence of switching ripples, the mode is single, the control mode is simplified, the mode switching management is avoided, and the chip area and the power consumption can be reduced.
Optionally, step S24 further includes:
s241: the sampling frequency is adjusted based on the current switching frequency.
The sampling frequency is the frequency at which the bandwidth adjustable error amplifier 132 samples the output voltage.
S242: and adjusting the bandwidth of the bandwidth adjustable error circuit based on the adjusted sampling frequency to adjust the bandwidth of the conversion circuit based on the current switching frequency.
The bandwidth of the adjusted conversion circuit is less than one fifth of the current switching frequency, and the ratio of the sampling frequency to the bandwidth of the bandwidth-adjustable error circuit is equal to the ratio of the adjusted sampling frequency to the bandwidth of the bandwidth-adjustable error circuit.
Alternatively, the method shown in fig. 5 can achieve similar effects to the method shown in fig. 4.
The present application also provides a power supply apparatus, which at least includes a switching power supply converting circuit 10, and the switching power supply converting circuit 10 is used for power supply management and control. The switching power supply converting circuit 10 is the switching power supply converting circuit 10 described in the above embodiments, and is not described herein again.
Different from the prior art, the power supply device of the application adopts the switching power supply conversion circuit 10 which can change the loop bandwidth according to the switching frequency, so that the bandwidth of a circuit system of the feedback loop for the output voltage VOUT is always less than one fifth of the switching frequency. Therefore, the control of the circuit from high output to low output can be simplified, the stability of a circuit system can be ensured without switching a control mode, and the influence of switching ripples on the output can be reduced.
The switching power supply converting circuit 10 that this application supplied includes the adjustable error circuit of bandwidth 13, the adjustable error circuit of bandwidth 13 can sample converting circuit 10's switching frequency, and adjust sampling frequency according to switching frequency, make the circuit system bandwidth be less than switching frequency all the time, make load 20 power switching ripple when less also can not be enlargied, be favorable to circuit system's stability, and realized the power control from high output to the whole output range of low output with a circuit, control system's complexity and chip cost have been reduced, make converting circuit 10's output voltage VOUT always remain stable under arbitrary output current. Meanwhile, the bandwidth of the circuit system is ensured to be always less than one fifth of the switching frequency, and the stability is improved while the high response speed of the circuit is kept.
The above description is only for the purpose of illustrating embodiments of the present application and is not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings of the present application or are directly or indirectly applied to other related technical fields, are also included in the scope of the present application.

Claims (9)

1. A switching power converter circuit, comprising:
the first end of the switch circuit is connected with a power supply;
the first end of the filter circuit is connected with the third end of the switch circuit, and the second end of the filter circuit is connected with a load;
a first end of the bandwidth adjustable error circuit is connected with a second end of the filter circuit, and a second end of the bandwidth adjustable error circuit is connected with a second end of the switch circuit;
the bandwidth adjustable error circuit receives a current output voltage from a second end of the filter circuit, and obtains a switching frequency based on the current output voltage, wherein the switching frequency is used for controlling the switching circuit to work; the bandwidth adjustable error circuit acquires the current switching frequency from the switch circuit, adjusts the bandwidth of the conversion circuit according to the current switching frequency, and the adjusted bandwidth of the conversion circuit is smaller than one fifth of the current switching frequency;
the bandwidth adjustable error circuit adjusts the sampling frequency based on the current switching frequency, and adjusts the bandwidth of the bandwidth adjustable error circuit based on the adjusted sampling frequency, so as to adjust the bandwidth of the conversion circuit based on the current switching frequency;
and the ratio of the sampling frequency to the bandwidth of the bandwidth adjustable error circuit is equal to the ratio of the adjusted sampling frequency to the bandwidth of the adjusted bandwidth adjustable error circuit.
2. The conversion circuit of claim 1, wherein the bandwidth adjustable error circuit comprises a comparator and a bandwidth adjustable error amplifier;
a first input end of the bandwidth adjustable error amplifier receives a reference voltage, a second input end of the bandwidth adjustable error amplifier is connected with a second end of the filter circuit, and the bandwidth adjustable error amplifier further receives the current switching frequency of the switch circuit;
the sampling frequency is the frequency of the output voltage sampled by the bandwidth-adjustable error amplifier;
the first input end of the comparator is connected with the second end of the filter circuit, the second input end of the comparator is connected with the output end of the adjustable bandwidth error amplifier, the third input end of the comparator receives a first voltage, and the output end of the comparator is connected with the second end of the switch circuit and used for outputting the switching frequency.
3. The conversion circuit of claim 2, wherein the bandwidth adjustable error circuit further comprises a time calculation circuit;
the first end of the time calculation circuit is connected with the output end of the comparator, and the second end of the time calculation circuit is connected with the second end of the switch circuit;
the time calculation circuit is used for adjusting the conduction time of each switching tube in the switching circuit to generate the switching frequency.
4. The conversion circuit of claim 3,
the switching circuit comprises a switching driver, a first switching tube and a second switching tube;
the first end of the first switch tube receives a power supply voltage, and the second end of the first switch tube is connected with the first end of the filter circuit;
the first end of the second switching tube is grounded, and the second end of the second switching tube is connected with the first end of the filter circuit;
the first end of the switch driver is connected with the output end of the bandwidth adjustable error circuit, the second end of the switch driver is connected with the control end of the first switch tube, and the third end of the switch driver is connected with the control end of the second switch tube, so that the first switch tube and the second switch tube are controlled to be conducted based on the switching frequency.
5. The conversion circuit of claim 4,
the filter circuit comprises an inductor and a capacitor;
the first end of the inductor is connected with the second end of the first switching tube and the second end of the second switching tube, and the second end of the inductor is connected with the load of the conversion circuit and the first end of the bandwidth adjustable error circuit;
the first end of the capacitor is connected with the second end of the inductor, and the second end of the capacitor is grounded.
6. The conversion circuit of claim 5,
the adjustable-bandwidth error circuit receives a current switching frequency of the switching circuit from the first end of the inductor.
7. A control method of a switching power supply conversion circuit, applied to the switching power supply conversion circuit according to any one of claims 1 to 6, the method comprising:
receiving the current output voltage from the filter circuit;
obtaining the switching frequency based on the current output voltage;
acquiring the current switching frequency;
and adjusting the bandwidth of the conversion circuit according to the current switching frequency, wherein the adjusted bandwidth of the conversion circuit is smaller than the current switching frequency.
8. The method of claim 7, wherein the step of adjusting the bandwidth of the conversion circuit according to the current switching frequency, the adjusted bandwidth of the conversion circuit being smaller than the current switching frequency comprises:
adjusting a sampling frequency based on the current switching frequency;
adjusting the bandwidth of the bandwidth adjustable error circuit based on the adjusted sampling frequency to achieve the adjustment of the bandwidth of the conversion circuit based on the current switching frequency;
the bandwidth of the adjusted conversion circuit is less than one fifth of the current switching frequency, and the ratio between the sampling frequency and the bandwidth of the bandwidth-adjustable error circuit is equal to the ratio between the adjusted sampling frequency and the bandwidth of the adjusted bandwidth-adjustable error circuit.
9. A power supply apparatus comprising the switching power supply conversion circuit according to any one of claims 1 to 6.
CN202111206963.3A 2021-10-18 2021-10-18 Power supply device, switching power supply conversion circuit and control method thereof Active CN113644822B (en)

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CN105375782A (en) * 2015-09-15 2016-03-02 成都芯源系统有限公司 Switching power supply and control circuit and method thereof
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