CN113676041A - Slope compensation control circuit, slope compensation control method and switch control circuit - Google Patents
Slope compensation control circuit, slope compensation control method and switch control circuit Download PDFInfo
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- CN113676041A CN113676041A CN202110709317.2A CN202110709317A CN113676041A CN 113676041 A CN113676041 A CN 113676041A CN 202110709317 A CN202110709317 A CN 202110709317A CN 113676041 A CN113676041 A CN 113676041A
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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
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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
- H02M1/00—Details of apparatus for conversion
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Abstract
The invention provides a slope compensation control circuit, a slope compensation control method and a switch control circuit. The slope compensation control circuit comprises a conduction time acquisition circuit, an arithmetic circuit and a slope compensation signal generation circuit. The input end of the conduction time acquisition circuit receives a switch control signal of the switch tube, the conduction time acquisition circuit acquires a first characterization signal for characterizing first conduction time according to the switch control signal, and the first conduction time is acquired by acquiring the conduction time of at least one switch period before the current switch period. The arithmetic circuit is coupled to the on-time obtaining circuit and is used for performing arithmetic processing on the first characterization signal so as to output a first arithmetic signal. The slope compensation signal generating circuit is used for outputting a slope compensation signal according to the first operation signal. The slope compensation control circuit, the slope compensation control method and the switch control circuit can be effectively matched with various application scenes, can perform slope compensation in a self-adaptive manner, and improve the stability of a system.
Description
Technical Field
The present invention relates to a slope compensation technique, and more particularly, to a slope compensation control circuit, a control method thereof, and a switch control circuit.
Background
Taking the current-mode PWM control system as an example, when the duty ratio of the current-mode PWM control system exceeds a certain point, the PWM control system may oscillate at a subharmonic frequency point of the switching frequency. As shown in fig. 1, when the on-time Ton of the switching tube in the PWM control system is greater than the off-time Toff, the current signal Ipk flowing through the inductor will oscillate, which will affect the stability of the PWM control system.
In order to ensure stable operation of the PWM control system, a slope compensation circuit is introduced into the PWM control system, where the slope compensation generally starts from a fixed starting point, usually from a starting point when the switching tube is in a conducting state, or starts from a point when the duty ratio exceeds a certain point. The stability of the PWM control system can be effectively increased by carrying out slope compensation on the current signal Ipk. In the case as in fig. 2, slope compensation is introduced, under which the current signal Ipk (waveform of the solid line) in the PWM control system will tend to stabilize after several cycles. When the current signal Ipk is disturbed, the amount of change of the current signal Ipk in the initial stage is Δ I0, and the current signal Ipk will become a waveform of a dotted line in fig. 2. In the slope compensation mode of fig. 2, the compensation effect may cause the slope compensation amplitude to be too large, and the amplitude of the PWM control system plus the slope compensation amplitude is the true peak current Ipk 1. An excessive magnitude of the slope compensation will affect the effective control of the PWM control system on the current signal Ipk. In different PWM control systems, the required slope compensation amplitude is often different. An unreasonable slope compensation amplitude setting can also result in the PWM control system not operating stably.
In view of the above, there is a need to provide a new structure or control method for solving at least some of the above problems.
Disclosure of Invention
The invention provides a slope compensation control circuit, a slope compensation control method and a switch control circuit, aiming at one or more problems in the prior art.
One embodiment of the present invention discloses a slope compensation control circuit for slope compensation of a switching control circuit, the slope compensation control circuit comprising:
the input end of the conduction time acquisition circuit receives a switch control signal of a switch tube and is used for acquiring a first characterization signal for characterizing first conduction time according to the switch control signal, wherein the first conduction time is obtained by acquiring the conduction time of at least one switch period before the current switch period;
the input end of the arithmetic circuit is coupled with the conduction time acquisition circuit and is used for carrying out arithmetic processing on the first characterization signal so as to output a first arithmetic signal; and
and the input end of the slope compensation signal generating circuit is coupled with the operational circuit and used for outputting a slope compensation signal according to the first operational signal.
As an embodiment of the present invention, the on-time obtaining circuit includes a sample-and-hold circuit, and the sample-and-hold circuit is configured to sample-and-hold an electrical signal representing the first on-time according to the switch control signal to obtain the first characterization signal.
As an embodiment of the present invention, the on-time obtaining circuit includes a first timing circuit, and the first timing circuit is configured to obtain an on-time of at least one switching cycle before a current switching cycle according to the switching control signal so as to obtain a first characterization signal.
As an embodiment of the present invention, the first characterization signal is a time signal or a voltage signal.
In an embodiment of the present invention, the operation circuit is configured to perform operation processing on the first characterization signal so that the first operation signal is K times of the first characterization signal, where 0< K < 1.
As an embodiment of the present invention, the on-time obtaining circuit is further configured to obtain a second characterization signal characterizing a second on-time according to the switch control signal, where the second on-time is a time from a time when the switching tube starts to be turned on to a current time in a current switching period; the slope compensation signal generation circuit includes:
and the first input end of the comparison circuit is coupled with the conduction time acquisition circuit, and the second input end of the comparison circuit is coupled with the operation circuit and used for comparing the second characterization signal with the first operation signal and outputting a comparison result signal as a trigger condition of slope compensation.
In an embodiment of the present invention, the first operation signal is a time signal, and the slope compensation signal generation circuit starts slope compensation when the on-time in the current switching period reaches the first operation signal.
As an embodiment of the present invention, the on-time acquisition circuit includes:
a first current source for providing a first current;
a first switch, a first end of which is coupled to the output end of the first current source, and a second end of which is coupled to the ground;
a first capacitor, a first end of which is coupled to the first end of the first switch, and a second end of which is coupled to ground;
a first follower, a first input terminal of which is coupled to the first terminal of the first capacitor, and a second input terminal of which is coupled to the output terminal of the first follower;
a first end of the second switch is coupled with the output end of the first follower;
a first end of the second capacitor is coupled with the second end of the second switch, and a second end of the second capacitor is coupled with the ground;
a first input end of the second follower is coupled with a first end of the second capacitor, and a second input end of the second follower is coupled with an output end of the second follower;
a first end of the third switch is coupled with the output end of the second follower; and
a first end of the third capacitor is coupled to the second end of the third switch, and a second end of the third capacitor is coupled to ground.
As an embodiment of the present invention, an input terminal of the operational circuit is coupled to a first terminal of a third capacitor; the slope compensation signal generating circuit comprises a comparison circuit, wherein a first input end of the comparison circuit is coupled with a first end of a first capacitor, and a second input end of the comparison circuit is coupled with an output end of an arithmetic circuit.
The invention further discloses a switch control circuit, which is used for controlling the switch tube and comprises the slope compensation control circuit.
One embodiment of the present invention further discloses a slope compensation control method for slope compensation of a switch control circuit, wherein the slope compensation control method comprises:
receiving a switch control signal of a switch tube, and acquiring a first characterization signal for characterizing first conduction time according to the switch control signal, wherein the first conduction time is acquired by acquiring the conduction time of at least one switch cycle before the current switch cycle;
performing operation processing on the first characterization signal so as to output a first operation signal; and
and outputting a slope compensation signal according to the first operation signal.
As an embodiment of the present invention, the step of obtaining a first characterization signal characterizing the first on-time according to the switch control signal specifically includes: and sampling and holding the electric signal representing the first conduction time according to the switch control signal so as to obtain a first representation signal.
As an embodiment of the present invention, the step of obtaining a first characterization signal characterizing the first on-time according to the switch control signal specifically includes: and timing the switch control signal to obtain the conduction time of at least one switching period before the current switching period so as to obtain a first characterization signal.
In one embodiment of the present invention, the first characterization signal is processed such that the first processed signal is K times the first characterization signal, where 0< K < 1.
As an embodiment of the present invention, a second characterization signal characterizing a second conduction time is obtained according to a switch control signal, where the second conduction time is a conduction time from a time when a switching tube starts to be conducted to a current time in a current switching period; and comparing the second characterization signal with the first operation signal, and outputting a comparison result signal as a trigger condition of slope compensation.
In an embodiment of the present invention, the first operation signal is a time signal, and slope compensation is started when the on-time in the current switching period reaches the first operation signal.
The invention provides a slope compensation control circuit, a slope compensation control method and a switch control circuit. The slope compensation control circuit is used for slope compensation of the switch control circuit. The slope compensation control circuit comprises a conduction time acquisition circuit, an arithmetic circuit and a slope compensation signal generation circuit. The input end of the conduction time acquisition circuit receives a switch control signal of the switch tube, the conduction time acquisition circuit is used for acquiring a first characterization signal for characterizing first conduction time according to the switch control signal, and the first conduction time is acquired by acquiring the conduction time of at least one switch period before the current switch period. The input end of the operational circuit is coupled with the on-time acquisition circuit, and the operational circuit is used for performing operational processing on the first characterization signal so as to output a first operational signal. The input end of the slope compensation signal generating circuit is coupled with the operational circuit, and the slope compensation signal generating circuit is used for outputting a slope compensation signal according to the first operational signal. The slope compensation control circuit, the slope compensation control method and the switch control circuit can be effectively matched with various application scenes, can perform slope compensation in a self-adaptive manner, and improve the stability of a system.
Drawings
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings:
FIG. 1 is a waveform diagram illustrating a current signal flowing through an inductor in a prior art PWM control system;
FIG. 2 is a waveform diagram illustrating a current signal flowing through an inductor in another prior art PWM control system;
FIG. 3 is a circuit diagram of a slope compensation control circuit according to an embodiment of the invention;
FIG. 4 is a circuit diagram of a slope compensation control circuit according to another embodiment of the present invention;
FIG. 5 is a circuit diagram of a slope compensation control circuit according to another embodiment of the present invention;
FIG. 6 illustrates a waveform diagram of a current signal according to an embodiment of the invention;
fig. 7 shows a waveform diagram of a current signal according to another embodiment of the invention.
Detailed Description
For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.
The description in this section is for several exemplary embodiments only, and the present invention is not limited only to the scope of the embodiments described. Combinations of different embodiments, and substitutions of features from different embodiments, or similar prior art means may be substituted for or substituted for features of the embodiments shown and described.
The term "coupled" or "connected" in this specification includes both direct and indirect connections. An indirect connection is a connection made through an intermediate medium, such as a conductor, wherein the electrically conductive medium may contain parasitic inductance or parasitic capacitance, or through an intermediate circuit or component as described in the embodiments in the specification; indirect connections may also include connections through other active or passive devices that perform the same or similar function, such as connections through switches, signal amplification circuits, follower circuits, and so on. "plurality" or "plurality" means two or more.
The invention discloses a slope compensation control circuit, which is used for slope compensation of a switch control circuit and comprises a conduction time acquisition circuit, an arithmetic circuit and a slope compensation signal generation circuit. The input end of the conduction time acquisition circuit receives a switch control signal of the switch tube, the conduction time acquisition circuit is used for acquiring a first characterization signal for characterizing first conduction time according to the switch control signal, and the first conduction time is acquired by acquiring the conduction time of at least one switch period before the current switch period. The input end of the operational circuit is coupled with the on-time acquisition circuit, and the operational circuit is used for performing operational processing on the first characterization signal so as to output a first operational signal. The input end of the slope compensation signal generating circuit is coupled with the operational circuit, and the slope compensation signal generating circuit is used for outputting a slope compensation signal according to the first operational signal. The slope compensation control circuit provided by the invention is different from the existing slope compensation technology in that various application scenes can be effectively matched, the slope compensation can be carried out in a self-adaptive manner, the system can enter a stable working state more quickly and easily, and the stability of the system is improved.
In an embodiment of the present invention, as shown in fig. 3, the slope compensation control circuit 10 includes a turn-on time obtaining circuit 11, an arithmetic circuit 12 and a slope compensation signal generating circuit 13. The input end of the on-time obtaining circuit 11 receives a switch control signal PWM of the switching tube, and the on-time obtaining circuit 11 is configured to obtain a first characterization signal characterizing a first on-time according to the switch control signal PWM, where the first on-time is an on-time of a switching period before a current switching period, that is, a certain switching period before the current switching period may be selected. Preferably, the first on-time is an on-time of a switching cycle previous to the current switching cycle. The input end of the arithmetic circuit 12 is coupled to the output end of the on-time obtaining circuit 11, and the arithmetic circuit 12 is configured to perform arithmetic processing on the first characterization signal so as to output a first arithmetic signal. In an embodiment of the present invention, the operation circuit 12 is configured to perform an operation on the first characterization signal such that the first operation signal is K times the first characterization signal, where 0< K < 1. In an embodiment of the invention, the first characterization signal may be a time signal or a voltage signal. In this embodiment, the first characterization signal is a time signal, and the first operation signal output by the operation circuit 12 is K × Ton _ n-1, where Ton _ n-1 is the on-time of the previous switching cycle of the current switching cycle. The input terminal of the slope compensation signal generating circuit 13 is coupled to the output terminal of the arithmetic circuit 12, and the slope compensation signal generating circuit 13 is configured to output the slope compensation signal Iramp according to the first arithmetic signal.
In another embodiment of the present invention, the on-time obtaining circuit is configured to obtain a first characterization signal characterizing a first on-time according to the switch control signal, where the first on-time is obtained by obtaining on-times of two switching cycles before a current switching cycle. Illustratively, the respective on-times of two switching cycles before the current switching cycle are Ton _ n-2 and Ton _ n-1, respectively, and the first on-time may be equal to the sum of the on-times of the two switching cycles, i.e. the first on-time is equal to (Ton _ n-2) + (Ton _ n-1). The first on-time may also be equal to the average of the respective on-times of the two switching cycles, i.e. the first on-time is equal to [ (Ton _ n-2) + (Ton _ n-1) ]/2. When a plurality of switching cycles are selected, the analogy can be done, and the description is omitted here.
In an embodiment of the present invention, the on-time obtaining circuit includes a sample-and-hold circuit, and the sample-and-hold circuit is configured to sample-and-hold the electrical signal representing the first on-time according to the switch control signal to obtain the first characterization signal.
In an embodiment of the invention, the on-time obtaining circuit includes a first timing circuit, and the first timing circuit is configured to obtain the on-time of at least one switching cycle before the current switching cycle according to the switching control signal so as to obtain the first characterization signal.
In another embodiment of the present invention, as shown in fig. 4, the slope compensation control circuit 20 includes an on-time acquisition circuit 21, an arithmetic circuit 22, and a slope compensation signal generation circuit 23. The slope compensation signal generation circuit 23 includes a comparison circuit 231. The input terminal of the on-time obtaining circuit 21 is coupled to the switch control signal terminal, and the switch control signal terminal is used for providing the switch control signal PWM of the switch tube. The on-time obtaining circuit 21 is configured to obtain a first characterization signal representing a first on-time according to the switch control signal PWM, where the first on-time is an on-time of a previous switching period of a current switching period, so as to obtain a first characterization signal Ton _ n-1. The input terminal of the operation circuit 22 is coupled to the output terminal of the on-time obtaining circuit 21, and the operation circuit 22 is configured to perform operation processing on the first characterization signal so that the first operation signal is K times of the first characterization signal, where 0< K < 1. In an embodiment of the present invention, the on-time obtaining circuit 21 is further configured to obtain a second characterization signal Ton _ n' characterizing a second on-time according to the switch control signal PWM, where the second on-time is a time from a time when the switching tube starts to be turned on to a current time in a current switching period. The first input terminal of the comparison circuit 231 is coupled to the output terminal of the on-time obtaining circuit 21, the second input terminal of the comparison circuit 231 is coupled to the output terminal of the operation circuit 22, the comparison circuit 231 is configured to compare the second characterization signal Ton _ n' with the first operation signal K × Ton _ n-1, and the comparison circuit 231 outputs a comparison result signal as a trigger condition of slope compensation through comparison. When the second characterization signal Ton _ n' reaches K × Ton _ n-1, slope compensation will start. In an embodiment of the present invention, the slope compensation control circuit is used for slope compensation of the inductor current to be controlled by the switch control circuit, and the slope compensation control circuit outputs the slope compensation signal Iramp, so that the system can rapidly enter a stable operating state. The inductor current is a current signal flowing through the inductor. It should be noted that the slope compensation control circuit for slope compensation of the inductor current is only one embodiment in many application scenarios, and the slope compensation control circuit of the present invention can be applied to other control circuits that need to make the system operate stably and apply slope compensation.
In an embodiment of the invention, the first operation signal is a time signal, and the slope compensation signal generation circuit starts to perform slope compensation when the on-time in the current switching period reaches the first operation signal.
As shown in fig. 5, in another embodiment of the present invention, the slope compensation control circuit includes an on-time control circuit 31, an operation circuit 32, and a slope compensation signal generation circuit 33. The on-time obtaining circuit 31 includes a first current source I1, a first switch S1, a first capacitor C1, a first follower 311, a second switch S2, a second capacitor C2, a second follower 312, a third switch S3, and a third capacitor C3. The first current source I1 is used to provide a first current. A first terminal of the first switch S1 is coupled to the output terminal of the first current source I1, and a second terminal of the first switch S1 is coupled to ground. The control terminal of the first switch S1 is coupled to the output terminal of the not gate, and the input terminal of the not gate is coupled to the switch control signal PWM of the switch tube. The first terminal of the first capacitor C1 is coupled to the first terminal of the first switch S1, and the second terminal of the first capacitor C1 is coupled to ground. A first input terminal of the first follower 311 is coupled to a first terminal of the first capacitor C1, and a second input terminal of the first follower 311 is coupled to an output terminal of the first follower 311. A first terminal of the second switch S2 is coupled to the output terminal of the first follower 311. The control terminal of the second switch S2 is coupled to the switching control signal PWM of the switching tube. The first terminal of the second capacitor C2 is coupled to the second terminal of the second switch S2, and the second terminal of the second capacitor C2 is coupled to ground. A first input terminal of the second follower 312 is coupled to a first terminal of the second capacitor C2, and a second input terminal of the second follower 312 is coupled to an output terminal of the second follower 312. A first terminal of the third switch S3 is coupled to the output terminal of the second follower 312. The control terminal of the third switch S3 is coupled to the output terminal of the not gate, and the input terminal of the not gate is coupled to the switch control signal of the switch tube. A first terminal of the third capacitor C3 is coupled to the second terminal of the third switch S3, and a second terminal of the third capacitor C3 is coupled to ground.
In an embodiment of the invention, as shown in fig. 5, the input terminal of the operation circuit 32 is coupled to the first terminal of the third capacitor C3. The operation circuit 32 performs operation processing on the first characterization signal so that the first operation signal is K times of the first characterization signal, where 0< K < 1. The slope compensation signal generating circuit 33 comprises a comparing circuit 331, wherein a first input terminal of the comparing circuit 331 is coupled to a first terminal of the first capacitor C1, and a second input terminal of the comparing circuit 331 is coupled to an output terminal of the computing circuit 32. The comparison circuit 331 outputs a comparison result signal as a trigger condition for slope compensation by comparison.
As shown in fig. 5, the on-time obtaining circuit 31 is configured to obtain a first characterization signal representing a first on-time according to the switch control signal PWM, where the first on-time is an on-time of a switching cycle previous to the current switching cycle. By holding the on-time sample of the previous switching period to the second capacitor C2, the voltage Vc2 on the second capacitor is transmitted to the third capacitor C3 when the switching tube is in the off-phase, so as to obtain the first characterization signal. The first input end of the comparison circuit 331 obtains a second characterization signal characterizing a second conduction time in real time, where the second conduction time is a conduction time from a time when the switching tube starts to be conducted to a current time in a current switching period. In this embodiment, the second characterization signal is a voltage signal, and when the second characterization signal that characterizes the second on-time reaches the first characterization signal that is K times, the Slope compensation signal generation circuit 33 outputs a Slope compensation signal Slope _ on, so as to perform Slope compensation on a control object of the switch control circuit, so that the system can quickly enter a stable state, and the stability of the system is improved.
As shown in fig. 6, in an embodiment of the present invention, the switching control circuit needs to control the peak value of the current flowing through a device in the system to be Iref, and slope compensation needs to be introduced to enable the system to quickly enter a stable operating state. When the switch tube is in the switching period T1, the on-time in the switching period T1 is Ton 1. In the switching period T2, the slope compensation control circuit starts slope compensation when the time counted from the time when the switching tube starts to be turned on reaches Ton1 × K, the slope compensation signal is shown by a dotted line in fig. 6, and the slope compensation process in the switching period T2 ends at the time when the switching tube is turned from the on state to the off state. Similarly, in the switching period T3, the slope compensation control circuit starts to perform slope compensation from the time when the switching tube starts to be turned on until the time reaches Ton2 × K, and the slope compensation process in the switching period T3 ends at the time when the switching tube is turned from the on state to the off state. It should be noted that the above is only an embodiment for describing the implementation principle of the present invention, and the present invention can also be implemented by other technical means for characterizing the on-time.
As shown in fig. 7, in another embodiment of the present invention, during the switching period T1 'and the switching period T2', no slope compensation is introduced, and the system is less stable. If the non-adaptive slope compensation of the prior art is introduced, the amplitude of the slope compensation signal cannot be effectively matched with the operating state of the system, and therefore the system is still relatively unstable. When the adaptive slope compensation is introduced, in the switching period T3 ', the slope compensation control circuit starts to perform slope compensation from the time when the switching tube starts to be turned on until the timing time reaches Ton2 × K, and the slope compensation process in the switching period T3' is ended at the time when the switching tube is turned from the on state to the off state. The following switching period T4 ', switching period T5', etc. can be analogized. Therefore, the slope compensation control circuit can adaptively perform slope compensation, so that the system can enter a stable working state more quickly and easily, and the stability of the system is improved.
An embodiment of the present invention further discloses a switch control circuit, wherein the switch control circuit is used for controlling a switch tube, and the switch control circuit comprises the slope compensation control circuit as described in any one of the above.
The embodiment of the invention also discloses a slope compensation control method, which is used for slope compensation of the switch control circuit and comprises the following steps:
receiving a switch control signal of a switch tube, and acquiring a first characterization signal for characterizing first conduction time according to the switch control signal, wherein the first conduction time is acquired by acquiring the conduction time of at least one switch cycle before the current switch cycle;
performing operation processing on the first characterization signal to output a first operation signal; and
and outputting a slope compensation signal according to the first operation signal.
The slope compensation control method provided by the invention can be effectively matched with various application scenes, can perform slope compensation in a self-adaptive manner, enables the system to enter a stable working state more quickly and easily, and improves the stability of the system.
In an embodiment of the invention, the on-time obtaining circuit receives a switch control signal of the switching tube, and the on-time obtaining circuit obtains a first characterization signal characterizing a first on-time according to the switch control signal, where the first on-time is obtained by obtaining an on-time of at least one switching cycle before a current switching cycle. The arithmetic circuit performs arithmetic processing on the first characterization signal to output a first arithmetic signal. The slope compensation signal generating circuit outputs a slope compensation signal according to the first operation signal. In a specific embodiment, the on-time of the switching cycle preceding the current switching cycle may be selected as the first on-time.
In another embodiment of the present invention, the step of obtaining the first characterization signal characterizing the first on-time according to the switch control signal specifically includes: the conduction time acquisition circuit samples and holds the electric signal representing the first conduction time according to the switch control signal so as to obtain a first representation signal.
In an embodiment of the present invention, the step of obtaining the first characterization signal characterizing the first on-time according to the switch control signal specifically includes: the on-time acquisition circuit acquires the on-time of at least one switching period before the current switching period by timing the switching control signal to acquire a first characterization signal.
In another embodiment of the present invention, the operation circuit performs an operation process on the first characterization signal such that the first operation signal is K times the first characterization signal, where 0< K < 1.
In an embodiment of the present invention, the conduction time obtaining circuit obtains a second characterization signal characterizing a second conduction time according to the switch control signal, where the second conduction time is a conduction time from a time when the switching tube starts to be conducted to a current time in a current switching period; the comparison circuit compares the second characterization signal with the first operation signal and outputs a comparison result signal as a trigger condition of slope compensation.
In another embodiment of the present invention, the first operation signal is a time signal, and the slope compensation is started when the on-time in the current switching period reaches the first operation signal.
Those skilled in the art should understand that the logic controls such as "high" and "low", "set" and "reset", "and gate" and "or gate", "non-inverting input" and "inverting input" in the logic controls referred to in the specification or the drawings may be exchanged or changed, and the subsequent logic controls may be adjusted to achieve the same functions or purposes as the above-mentioned embodiments.
The description and applications of the invention herein are illustrative and are not intended to limit the scope of the invention to the embodiments described above. The descriptions related to the effects or advantages in the specification may not be reflected in practical experimental examples due to uncertainty of specific condition parameters or influence of other factors, and the descriptions related to the effects or advantages are not used for limiting the scope of the invention. Variations and modifications of the embodiments disclosed herein are possible, and alternative and equivalent various components of the embodiments will be apparent to those skilled in the art. It will be clear to those skilled in the art that the present invention may be embodied in other forms, structures, arrangements, proportions, and with other components, materials, and parts, without departing from the spirit or essential characteristics thereof. Other variations and modifications of the embodiments disclosed herein may be made without departing from the scope and spirit of the invention.
Claims (16)
1. A slope compensation control circuit for slope compensation of a switching control circuit, the slope compensation control circuit comprising:
the input end of the conduction time acquisition circuit receives a switch control signal of a switch tube and is used for acquiring a first characterization signal for characterizing first conduction time according to the switch control signal, wherein the first conduction time is obtained by acquiring the conduction time of at least one switch period before the current switch period;
the input end of the arithmetic circuit is coupled with the conduction time acquisition circuit and is used for carrying out arithmetic processing on the first characterization signal so as to output a first arithmetic signal; and
and the input end of the slope compensation signal generating circuit is coupled with the operational circuit and used for outputting a slope compensation signal according to the first operational signal.
2. The slope compensation control circuit of claim 1, wherein the on-time acquisition circuit comprises a sample-and-hold circuit configured to sample-and-hold the electrical signal indicative of the first on-time based on the switch control signal to obtain the first characterization signal.
3. The slope compensation control circuit of claim 1, wherein the on-time acquisition circuit comprises a first timing circuit configured to obtain the on-time of at least one switching cycle prior to a current switching cycle based on the switching control signal to obtain a first characterization signal.
4. The slope compensation control circuit of claim 1, wherein the first characterization signal is a time signal or a voltage signal.
5. The slope compensation control circuit of claim 1, wherein the arithmetic circuit is configured to operate on the first characterization signal such that the first operation signal is K times the first characterization signal, where 0< K < 1.
6. The slope compensation control circuit of claim 2, wherein the on-time obtaining circuit is further configured to obtain a second characterization signal characterizing a second on-time according to the switch control signal, where the second on-time is a time from a time when the switch tube starts to be turned on to a current time in a current switch period; the slope compensation signal generation circuit includes:
and the first input end of the comparison circuit is coupled with the conduction time acquisition circuit, and the second input end of the comparison circuit is coupled with the operation circuit and used for comparing the second characterization signal with the first operation signal and outputting a comparison result signal as a trigger condition of slope compensation.
7. The slope compensation control circuit of claim 3, wherein the first operational signal is a time signal, and the slope compensation signal generating circuit starts slope compensation when the on-time in the current switching period reaches the first operational signal.
8. The slope compensation control circuit of claim 1, wherein the on-time acquisition circuit comprises:
a first current source for providing a first current;
a first switch, a first end of which is coupled to the output end of the first current source, and a second end of which is coupled to the ground;
a first capacitor, a first end of which is coupled to the first end of the first switch, and a second end of which is coupled to ground;
a first follower, a first input terminal of which is coupled to the first terminal of the first capacitor, and a second input terminal of which is coupled to the output terminal of the first follower;
a first end of the second switch is coupled with the output end of the first follower;
a first end of the second capacitor is coupled with the second end of the second switch, and a second end of the second capacitor is coupled with the ground;
a first input end of the second follower is coupled with a first end of the second capacitor, and a second input end of the second follower is coupled with an output end of the second follower;
a first end of the third switch is coupled with the output end of the second follower; and
a first end of the third capacitor is coupled to the second end of the third switch, and a second end of the third capacitor is coupled to ground.
9. The slope compensation control circuit of claim 8, wherein an input terminal of the arithmetic circuit is coupled to a first terminal of a third capacitor; the slope compensation signal generating circuit comprises a comparison circuit, wherein a first input end of the comparison circuit is coupled with a first end of a first capacitor, and a second input end of the comparison circuit is coupled with an output end of an arithmetic circuit.
10. A switching control circuit for controlling a switching tube, the switching control circuit comprising a slope compensation control circuit as claimed in any one of claims 1 to 9.
11. A slope compensation control method is used for slope compensation of a switch control circuit and is characterized by comprising the following steps:
receiving a switch control signal of a switch tube, and acquiring a first characterization signal for characterizing first conduction time according to the switch control signal, wherein the first conduction time is acquired by acquiring the conduction time of at least one switch cycle before the current switch cycle;
performing operation processing on the first characterization signal so as to output a first operation signal; and
and outputting a slope compensation signal according to the first operation signal.
12. The slope compensation control method of claim 11, wherein the step of obtaining a first characterization signal characterizing the first on-time based on the switch control signal comprises:
and sampling and holding the electric signal representing the first conduction time according to the switch control signal so as to obtain a first representation signal.
13. The slope compensation control method of claim 11, wherein the step of obtaining a first characterization signal characterizing the first on-time based on the switch control signal comprises:
and timing the switch control signal to obtain the conduction time of at least one switching period before the current switching period so as to obtain a first characterization signal.
14. The slope compensation control method of claim 11, wherein the first characterization signal is operated such that the first operated signal is K times the first characterization signal, where 0< K < 1.
15. The slope compensation control method according to claim 12, wherein a second characterization signal characterizing a second on-time is obtained according to the switch control signal, and the second on-time is a time from a time when the switch tube starts to be turned on to a current time in a current switch period; and comparing the second characterization signal with the first operation signal, and outputting a comparison result signal as a trigger condition of slope compensation.
16. The slope compensation control method as claimed in claim 13, wherein the first operation signal is a time signal, and the slope compensation is started when the on-time in the current switching period reaches the first operation signal.
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