CN116247908B - Switching converter control circuit, control method and power supply equipment - Google Patents
Switching converter control circuit, control method and power supply equipment Download PDFInfo
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- CN116247908B CN116247908B CN202310524618.7A CN202310524618A CN116247908B CN 116247908 B CN116247908 B CN 116247908B CN 202310524618 A CN202310524618 A CN 202310524618A CN 116247908 B CN116247908 B CN 116247908B
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Classifications
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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
- H02M1/0003—Details of control, feedback or regulation circuits
- H02M1/0012—Control circuits using digital or numerical techniques
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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
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
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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
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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Abstract
The invention discloses a control circuit, a control method and power equipment of a switching converter, wherein the control circuit comprises the following components: the first comparison input module is used for acquiring the input voltage of the switching converter and determining the first comparison input voltage according to the input voltage; the second comparison input module is used for obtaining the output voltage of the switching converter and determining a second comparison input voltage according to the output voltage; the comparison module is used for comparing the first comparison input voltage with the second comparison input voltage and outputting a conduction time control signal according to a voltage comparison result; the first comparison input module is provided with a delay compensation unit, and the delay compensation unit is used for carrying out lifting treatment on the first comparison input voltage according to the inherent delay time of the comparison module, so that the initial voltage of the first comparison input voltage is larger than zero. According to the self-adaptive on-time control circuit, the delay compensation unit is arranged in the self-adaptive on-time control circuit, so that the influence of inherent delay time on the switching frequency is avoided, the frequency stability is improved, and the design cost is reduced.
Description
Technical Field
The present invention relates to the field of power electronics, and in particular, to a control circuit, a control method, and a power supply device for a switching converter.
Background
The control method of the direct current-direct current converter (DC/DC) generally includes pulse width modulation (Pulse Width Modulation, PWM) and Constant On Time (COT). The COT control technique is a pulse frequency modulation (Pulse Frequency Modulation, PFM) control scheme. Compared with the traditional PWM control technology, COT control has the advantages of high light load efficiency, high transient response speed and the like, and is widely used in the switching power supply control technology.
FIG. 1 is a waveform diagram of a transient response of a load jump of a conventional switching converter in a current control mode; fig. 2 is a waveform diagram showing a transient response of a load jump of a conventional switching converter in a COT control mode. As shown in fig. 1 and 2, constant on-time control architectures typically use a reference comparator output to trigger the timing pulse generator instead of using a fixed frequency clock. The frequency of occurrence of the pulses is determined by the output load current. In steady state, the constant on-time control operates at approximately a fixed frequency. However, at load current I Load Transition from low to highIn the process, the pulse generator outputs the high frequency pulse SW to minimize the output undershoot. Once the normal output voltage is reached, the pulse frequency is reduced to the level required to maintain a stable regulated output voltage. Lower undershoot makes it easier to meet load voltage tolerance specifications. Compared to converters employing voltage or current control modes, converters based on constant on-time control modes require less output capacitance to meet a given load transient response, saving both space size and cost.
As shown in conjunction with fig. 1 and 2, for the same load current boost converter, the COT control has a faster switching speed, reducing the inductor current I L And output load current I Load The gap between them, thereby further reducing output undershoot.
The existing constant on-time control module has the following problems that the actual on-time is delayed relative to the theoretical on-time due to the inherent delay of the comparator of the switching converter, the delay breaks the rule that the on-time changes according to the theoretical situation, the switching frequency of the converter changes along with the change of the input voltage and the output voltage, the working frequency is not fixed, difficulty is brought to the optimization (such as inductance optimization) of a converter circuit, and larger electromagnetic interference is easy to generate, so that the performance of a switching power supply is influenced. In order to eliminate the influence caused by the input and output voltage variation, loop control can be adopted, but the design cost is high, and the design difficulty and risk are high.
Disclosure of Invention
The invention provides a switching power supply control circuit, a control method and power supply equipment, which are used for solving the problems that the working frequency of the conventional switching power supply control circuit is easily affected by input and output voltage changes and the design cost of a loop control mode is high, and effectively improving the frequency stability.
According to an aspect of the present invention, there is provided a switching converter control circuit provided with a switching element including:
the first comparison input module is used for acquiring the input voltage of the switching converter and determining a first comparison input voltage according to the input voltage;
the second comparison input module is used for acquiring the output voltage of the switching converter and determining a second comparison input voltage according to the output voltage;
the comparison module is used for comparing the first comparison input voltage with the second comparison input voltage and outputting a conduction time control signal according to a voltage comparison result;
the first comparison input module is provided with a delay compensation unit, and the delay compensation unit is used for carrying out lifting treatment on the first comparison input voltage according to the inherent delay time of the comparison module, so that the initial voltage of the first comparison input voltage is larger than zero.
Optionally, the first comparison input module includes: a charging current obtaining unit for outputting a charging current according to the input voltage; the charging capacitor is used for outputting charging voltage according to the charging current; the delay compensation unit is arranged between the charging current acquisition unit and the charging capacitor and is used for outputting lifting voltage according to the charging current; wherein the first comparison input voltage is equal to a sum of the charging voltage and the boosting voltage.
Optionally, the delay compensation unit includes a compensation resistor, a first end of the compensation resistor is connected with the charging current acquisition unit, and a second end of the compensation resistor is grounded through the charging capacitor; the first end of the compensation resistor is also electrically connected with the first input end of the comparison module; the resistance of the compensation resistor is positively correlated with the inherent delay time of the comparison module, and the resistance of the compensation resistor is negatively correlated with the capacitance of the charging capacitor.
Optionally, the first comparison input module further includes: the charging control switch is connected with the charging capacitor in parallel, the control end of the charging control switch is electrically connected with the output end of the comparison module, and the charging control switch is used for resetting or maintaining the charging voltage of the charging capacitor according to the on-time control signal.
Optionally, the second comparison input module includes: a plurality of voltage dividing resistors connected in series; the plurality of voltage dividing resistors include at least: the first voltage dividing resistor and the second voltage dividing resistor; the first end of the first voltage dividing resistor is electrically connected with the output end of the switching converter, and the second end of the first voltage dividing resistor is electrically connected with the first end of the second voltage dividing resistor; the second end of the second voltage dividing resistor is grounded; a sampling node is arranged between the first voltage dividing resistor and the second voltage dividing resistor, the sampling node is electrically connected with the first input end of the comparison module, and the sampling node is used for outputting sampling voltage based on a preset sampling signal; the sampling period of the preset sampling signal is equal to or approximately equal to the switching period of the switching converter.
Optionally, the voltage value of the initial voltage is equal to the delay trigger voltage difference value corresponding to the inherent delay time; the delay trigger voltage difference is a voltage difference between the first comparison input voltage and the second comparison input voltage when the comparison module is triggered in a delay mode.
According to another aspect of the present invention, there is provided a switching converter control method provided with a switching element for the above-described switching converter control circuit, the method comprising: acquiring the input voltage of the switching converter, and determining a first comparison input voltage according to the input voltage;
obtaining the output voltage of the switching converter, and determining a second comparison input voltage according to the output voltage;
comparing the first comparison input voltage with the second comparison input voltage, and outputting a conduction time control signal according to a voltage comparison result;
in determining a first comparison input voltage from the input voltages, the method includes:
and lifting the first comparison input voltage according to the inherent delay time of the comparison module, so that the initial voltage of the first comparison input voltage is larger than zero.
According to another aspect of the present invention, there is provided a power supply apparatus including: a DC-DC converter and the switch converter control circuit; the DC-DC converter is provided with a switching element; the switching converter control circuit is used for outputting a switching time control signal and controlling the switching element to be switched on or switched off according to the switching time control signal.
According to the technical scheme, the first comparison input module, the second comparison input module and the comparison module are arranged, the delay compensation unit is arranged on the first comparison input module, the first comparison input voltage is determined by the first comparison input module according to the input voltage, the delay compensation unit is used for carrying out lifting treatment on the first comparison input voltage according to the inherent delay time of the comparison module, so that the initial voltage of the first comparison input voltage is larger than zero, the second comparison input module determines the second comparison input voltage according to the output voltage of the switching converter, the problem that the working frequency of an existing switching power supply control circuit is easily influenced by the change of the input and output voltages and the design cost of a loop control mode is high is solved, the problem that the inherent delay time influences the switching frequency is avoided, the stability of the working frequency in a constant on time control mode is improved, a control loop is not needed, the circuit is simple, the reliability is high, and the design cost is low.
It should be understood that the description in this section is not intended to identify key or critical features of the embodiments of the invention or to delineate the scope of the invention. Other features of the present invention will become apparent from the description that follows.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a waveform diagram of a transient response of a load jump of a conventional switching converter in a current control mode;
FIG. 2 is a waveform diagram of a transient response of a load jump of a conventional switching converter in COT control mode;
fig. 3 is a schematic structural diagram of a switching converter control circuit according to a first embodiment of the present invention;
FIG. 4 is a schematic waveform diagram of the principle of generating on-time of a conventional switching converter in a state affected by delay;
fig. 5 is a schematic waveform diagram of an on-time generation principle of a switching converter control circuit according to an embodiment of the present invention;
fig. 6 is a schematic circuit diagram of a switching converter control circuit according to a first embodiment of the present invention;
fig. 7 is a flowchart of a switching converter control method according to a second embodiment of the present invention.
Detailed Description
In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
Example 1
Fig. 3 is a schematic structural diagram of a switching converter control circuit according to an embodiment of the present invention, where the embodiment is applicable to an application scenario in which the on time of a switching element in a switching converter is adjusted in a constant on time control mode, and the embodiment of the present invention can improve the stability of the operating frequency in the constant on time control mode.
Typically, switching converters include Buck dc-dc converters (Buck converters) and Boost dc-dc converters (Boost converters). The switching element of the switching converter includes: an upper power tube and a lower power tube.
As shown in fig. 3, the switching converter control circuit includes:
a first comparison input module 100 for obtaining an input voltage V of the switching converter IN And according to the input voltage V IN Determining a first comparison input voltage V COM1 The method comprises the steps of carrying out a first treatment on the surface of the Wherein the first comparison input voltage V COM1 Can be based on input voltage V IN A linearly varying ramp voltage.
A second comparison input module 200 for obtaining the output voltage V of the switching converter OUT And according to the output voltage V OUT Determining a second comparison input voltage V COM2 The method comprises the steps of carrying out a first treatment on the surface of the Wherein the second comparison input voltage V COM2 Can be based on the output voltage V OUT The generated reference voltage.
A comparison module 300 for comparing the first comparison input voltage V COM1 Comparing the input voltage V with a second comparison input voltage COM2 And comparing, and outputting a conduction time control signal according to the voltage comparison result.
As shown in fig. 3, the first comparison input module 100 is provided with a delay compensation unit 110, and the delay compensation unit 110 is used for adjusting the inherent delay time T of the comparison module 300 D For a first comparison input voltage V COM1 The voltage value of (2) is raised to make the first comparison input voltage V COM1 Is greater than zero.
Specifically, at the outputVoltage V OUT While fixed, the second comparison input voltage V COM2 Approximately unchanged, the first comparison input voltage V COM1 Is a ramp voltage. The comparison module 300 compares the input voltage V according to the first comparison COM1 Comparing the input voltage V with a second comparison input voltage COM2 The corresponding on-time control signal is output. When the first comparison input voltage V COM1 The voltage value of (2) is greater than or equal to the second comparison input voltage V COM2 The on-time control signal is set to a low level signal, i.e. an on-end signal for driving the switching element off while the first comparison input voltage V COM1 Resetting to a ground signal, and waiting for starting the next timing; when the first comparison input voltage V COM1 The voltage value of (2) is smaller than the second comparison input voltage V COM2 The on-time control signal maintains a high level signal, i.e., an on signal, for driving the switching element on.
In one embodiment, the first comparison input voltage V COM1 The voltage value of the initial voltage of the voltage transformer is equal to the delay trigger voltage difference value corresponding to the inherent delay time; wherein the delay trigger voltage difference is the first comparison input voltage V when the comparison module 300 is delay triggered COM1 Comparing the input voltage V with a second comparison input voltage COM2 Voltage difference between them.
FIG. 4 is a schematic waveform diagram of the principle of generating on-time in a state of a prior art switching converter affected by delay; fig. 5 is a schematic waveform diagram of an on-time generation principle of a switching converter control circuit according to an embodiment of the invention.
The principle of generating the on-time will be exemplarily described with reference to fig. 4 and 5 by taking a Buck dc-dc Converter (Buck Converter) in the constant on-time control mode as an example. If the output voltage of the switching converter is defined as V OUT The input voltage of the switching converter is V IN The switching period is T P Theoretical on-time T ON =T P *V OUT /V IN . Wherein the theoretical conduction time T ON And input voltage V IN Inversely proportional to the output powerPressure V OUT In direct proportion, the approximately constant frequency operation is maintained as the input/output voltage changes.
As shown in fig. 4, when the delay compensation unit 110 is not provided, the triggering of the comparison module 300 is affected by the delay. Ideally, when the first comparison input voltage V COM1 Equal to the second comparison input voltage V COM2 When the comparison module 300 is triggered. Due to the delay, the actual comparison module 300 will compare the input voltage V at the first voltage COM1 Rising to a second comparison input voltage V COM2 Then, the inherent delay time is T D Is triggered, resulting in an actual first comparison input voltage V when the comparison module 300 is triggered COM1 Higher than the second comparison input voltage V COM2 For example, the excess voltage difference may be defined as Δv. If the inherent delay time is defined as T D Delay on time T ON ' equals the theoretical on-time T ON And an inherent delay time T D And (3) summing.
As shown in fig. 5, after the delay compensation unit 110 is introduced, the first comparison input voltage V COM1 Is set to be at the initial voltage V of ST Rising to the voltage difference DeltaV, shortening the first comparison input voltage V COM1 Reaching the second comparison input voltage V COM2 For a time required for the first comparison input voltage V COM1 Reaching the second comparison input voltage V COM2 Time of actual on time T ON "equal to the theoretical on-time T ON The effect of the delay effect on the actual on-time can be eliminated.
According to the technical scheme, the delay compensation unit is arranged in the self-adaptive on-time control circuit, so that the delay effect of the comparison module is eliminated, the problem that the working frequency of the conventional switching power supply control circuit is easily influenced by input and output voltage changes and the design cost of a loop control mode is high is solved, the inherent delay time is prevented from influencing the switching frequency, the stability of the working frequency in a constant on-time control mode is improved, a control loop is not required to be designed, the circuit is simple, the reliability is high, and the design cost is low.
Fig. 6 is a schematic circuit diagram of a switching converter control circuit according to a first embodiment of the present invention.
As shown in fig. 6, the first comparison input module 100 includes: a charging current acquisition unit 120 for acquiring a charging current according to an input voltage V IN Output charging current I C The method comprises the steps of carrying out a first treatment on the surface of the A charging capacitor C1 for charging according to the charging current I C Outputting a charging voltage; the delay compensation unit 110 is disposed at the charging current I C Between the acquisition unit 120 and the charging capacitor C1, the delay compensation unit 110 is configured to compensate the charging current I C Output of the lifting voltage V ST The method comprises the steps of carrying out a first treatment on the surface of the Wherein the first comparison input voltage V COM1 Equal to the charging voltage V C And a lifting voltage V ST And (3) summing.
In one embodiment, the charging current obtaining unit 120 may be a voltage-current (V-I) converter, and if the transimpedance of the voltage-current (V-I) converter is defined as R, the charging current I C And input voltage V IN The following are satisfied:。
as shown in fig. 6, the first comparison input module 100 further includes: the charging control switch S1 is connected in parallel with the charging capacitor C1, the control end of the charging control switch S1 is electrically connected with the output end of the comparison module 300, and the charging control switch S1 is used for resetting or maintaining the charging voltage of the charging capacitor C1 according to the on-time control signal.
In this embodiment, when the on-time control signal is the on-end signal, the charge control switch S1 is controlled to be turned on, the charge control switch S1 shorts the two ends of the charge capacitor C1 to reset the charge voltage of the charge capacitor C1 to ground, and at this time, the first comparison input voltage V COM1 Equal to the lifting voltage V ST The method comprises the steps of carrying out a first treatment on the surface of the When the on-time control signal is an on-signal, the charge control switch S1 is controlled to be turned off, and at this time, the first comparison input voltage V COM1 Charging voltage and lifting voltage V equal to charging capacitor C1 ST And (3) summing.
Specifically, the charging current I C Charging the charging capacitor C1 to generate a ramp voltage, i.e. a first comparison input voltage V COM1 The comparison module 300 compares the first comparison input voltageV COM1 Comparing the input voltage V with a second comparison input voltage COM2 Comparing when the first comparison input voltage V COM1 The voltage value of (2) is smaller than the second comparison input voltage V COM2 The on-time control signal output by the comparison module 300 is an on-signal, and the switching element of the switching converter is continuously turned on; when the first comparison input voltage V COM1 The voltage value of (2) is greater than or equal to the second comparison input voltage V COM2 The on-time control signal outputted from the comparison module 300 is an on-end signal, and the first comparison input voltage V is inputted while the switching element (e.g., upper power tube) is turned off COM1 Reset to ground signal and wait for the next time to start.
As shown in fig. 6, the delay compensation unit 110 includes a compensation resistor R 110 Compensation resistor R 110 Is connected to the charging current obtaining unit 120, and compensates for the resistance R 110 The second end of the capacitor is grounded through a charging capacitor C1; compensation resistor R 110 Is also electrically connected to the first input of the comparison module 300; wherein, the compensation resistor R 110 Resistance of (c) and inherent delay time T of comparison module 300 D Positive correlation, and compensating resistance R 110 The resistance of (C) is inversely related to the capacitance C of the charging capacitor C1.
As shown in fig. 6, the second comparison input module 200 includes: a plurality of voltage dividing resistors connected in series. The plurality of voltage dividing resistors include at least: a first voltage dividing resistor R 201 And a second voltage dividing resistor R 202 The method comprises the steps of carrying out a first treatment on the surface of the A first voltage dividing resistor R 201 A first voltage dividing resistor R electrically connected with the output end of the switching converter 201 And a second voltage-dividing resistor R 202 Is electrically connected to the first end of the first connector; second voltage-dividing resistor R 202 Is grounded; a first voltage dividing resistor R 201 And a second voltage-dividing resistor R 202 A sampling node P is arranged between the first input end and the second input end of the comparison module 300, and is electrically connected with the first input end of the comparison module 300, and the sampling node P is used for outputting sampling voltage based on a preset sampling signal; the sampling period of the preset sampling signal is equal to or approximately equal to the switching period of the switching converter.
As described in connection with FIGS. 4 to 6Charging current I is shown C And input voltage V IN The following are satisfied:. If the capacitance value of the charging capacitor C1 is C, a first voltage dividing resistor R 201 Has a resistance value of R TOP Second voltage-dividing resistor R 202 Has a resistance value of R BOT Theoretical on-time T ON Satisfying equation one as shown below:
(equation I)
Wherein,,。
as shown in fig. 4 and 6, when the delay compensation unit 110 is not provided, the delay on time T ON ' is prolonged by the effect of a delay, the time of the delayed conduction T ON ' satisfy equation two as shown below:
(equation II)
Wherein DeltaV is the first comparison input voltage V when the comparison module 300 is triggered under the influence of the delay effect COM1 Comparing the input voltage V with a second comparison input voltage COM2 Voltage difference between them.
As shown in fig. 4 to 6, after the delay compensation unit 110 is introduced, the delay compensation unit is controlled by compensating the delay resistance R 110 For a first comparison input voltage V COM1 Is subjected to lifting treatment, and the voltage V is lifted ST Satisfying equation three as follows:
(equation three)
Wherein R is RMP To compensate for the resistance of resistor R110.
Referring to FIG. 5, a first comparison input voltage V COM1 Not 0V, but a value higher than 0V, i.e. the boost voltage V ST At this time, the actual on time T ON "satisfies the following formula four:
(equation IV)
Wherein V is ST For charging current I C Compensated resistor R 110 The voltage value resulting from the voltage division.
In the embodiment of the invention, the lifting voltage V is set based on the requirement of eliminating the delay effect ST Let the actual on-time T =DeltaV ON "equal to the theoretical on-time T ON 。
As can be seen from the combination of the above formulas II, III and IV, the compensation resistor R can be set 110 Resistance value R of (2) RMP Satisfying equation five as shown below:
(equation five)
It should be noted that the inherent delay time T of the comparison module 300 D Depending on the design of the comparator and the process used, the above equation V and the inherent delay time T of the comparator can be combined after the design of the comparator is completed D Calculating compensation resistance R 110 Is a resistance value of (a).
Example two
Based on the same inventive concept, the second embodiment of the invention also provides a control method of the switching converter, which is realized based on the control circuit of the switching converter and can be used for improving the stability of the working frequency of the direct current-direct current converter in a constant on-time control mode.
Fig. 7 is a flowchart of a switching converter control method according to a second embodiment of the present invention.
As shown in fig. 7, the switching converter control method includes the steps of:
s1: an input voltage of the switching converter is obtained and a first comparison input voltage is determined from the input voltage.
S2: and lifting the first comparison input voltage according to the inherent delay time of the comparison module, so that the initial voltage of the first comparison input voltage is greater than zero.
As shown in combination with fig. 4 and 5, the first comparison input voltage V COM1 The voltage value of the initial voltage of the voltage transformer is equal to the delay trigger voltage difference value corresponding to the inherent delay time; wherein the delay trigger voltage difference is the first comparison input voltage V when the comparison module 300 is delay triggered COM1 Comparing the input voltage V with a second comparison input voltage COM2 Voltage difference between them.
S3: the output voltage of the switching converter is obtained and a second comparison input voltage is determined from the output voltage.
S4: comparing the first comparison input voltage with the second comparison input voltage, and outputting a conduction time control signal according to a voltage comparison result.
Optionally, determining the first comparison input voltage from the input voltage comprises: outputting a charging current according to the input voltage; determining a charging voltage according to the charging current, and determining a lifting voltage according to the charging current; wherein the first comparison input voltage is equal to the sum of the charging voltage and the boosting voltage.
In one embodiment, the step of raising the first comparison input voltage according to the inherent delay time of the comparison module includes: determining the resistance value of the compensation resistor according to the inherent delay time of the comparison module and the capacitance value of the charging capacitor; lifting the first comparison input voltage based on the compensation resistor; the resistance of the compensation resistor is positively correlated with the inherent delay time of the comparison module, and the resistance of the compensation resistor is negatively correlated with the capacitance of the charging capacitor.
Optionally, determining the first comparison input voltage from the input voltage further comprises: and resetting or maintaining the charging voltage of the charging capacitor according to the on-time control signal.
Optionally, determining the second comparison input voltage from the output voltage includes: acquiring a sampling voltage of an output end of the switching converter based on a preset sampling signal, and determining the sampling voltage as a second comparison input voltage; the sampling period of the preset sampling signal is equal to or approximately equal to the switching period of the switching converter.
According to the technical scheme, the input voltage of the switching converter is obtained, the first comparison input voltage is determined according to the input voltage, and lifting processing is carried out on the first comparison input voltage according to the inherent delay time of the comparator, so that the initial voltage of the first comparison input voltage is larger than zero; the method comprises the steps of obtaining output voltage of the switching converter, determining second comparison input voltage according to the output voltage, comparing the first comparison input voltage with the second comparison input voltage, outputting a conduction time control signal according to a voltage comparison result, and setting delay compensation in a self-adaptive conduction time control mode to avoid the influence of inherent delay time on switching frequency, improve frequency stability and reduce design cost.
Example III
Based on the above embodiments, a third embodiment of the present invention provides a power supply apparatus including: a DC-DC converter and the switch converter control circuit; the DC-DC converter is provided with a switching element; the switching converter control circuit is used for outputting a conduction time control signal and controlling the switching element to be turned on or turned off according to the conduction time control signal.
In the embodiment of the invention, the switch converter control circuit is provided with the first comparison input module, the second comparison input module and the comparison module, the first comparison input module is provided with the delay compensation unit, the first comparison input module determines the first comparison input voltage according to the input voltage, the delay compensation unit is used for lifting the first comparison input voltage according to the inherent delay time of the comparison module, so that the initial voltage of the first comparison input voltage is greater than zero, the second comparison input module determines the second comparison input voltage according to the output voltage of the switch converter, the problem that the working frequency of the conventional switch power supply control circuit is easily influenced by the change of the input and output voltages and the design cost of a loop control mode is high is solved, the inherent delay time is prevented from influencing the switching frequency, the stability of the working frequency in a constant on time control mode is improved, a control loop is not required to be designed, the circuit is simple, the reliability is high, and the design cost is low.
It should be appreciated that various forms of the flows shown above may be used to reorder, add, or delete steps. For example, the steps described in the present invention may be performed in parallel, sequentially, or in a different order, so long as the desired results of the technical solution of the present invention are achieved, and the present invention is not limited herein.
The above embodiments do not limit the scope of the present invention. It will be apparent to those skilled in the art that various modifications, combinations, sub-combinations and alternatives are possible, depending on design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of the present invention.
Claims (7)
1. A switching converter control circuit provided with a switching element, comprising:
the first comparison input module is used for acquiring the input voltage of the switching converter and determining a first comparison input voltage according to the input voltage;
the second comparison input module is used for acquiring the output voltage of the switching converter and determining a second comparison input voltage according to the output voltage;
the comparison module is used for comparing the first comparison input voltage with the second comparison input voltage and outputting a conduction time control signal according to a voltage comparison result;
the first comparison input module is provided with a delay compensation unit, and the delay compensation unit is used for carrying out lifting treatment on the first comparison input voltage according to the inherent delay time of the comparison module so that the initial voltage of the first comparison input voltage is larger than zero;
the voltage value of the initial voltage is equal to the delay trigger voltage difference value corresponding to the inherent delay time;
the delay trigger voltage difference is a voltage difference between the first comparison input voltage and the second comparison input voltage when the comparison module is triggered in a delay mode.
2. The control circuit of claim 1, wherein the first comparison input module comprises:
a charging current obtaining unit for outputting a charging current according to the input voltage;
the charging capacitor is used for outputting charging voltage according to the charging current;
the delay compensation unit is arranged between the charging current acquisition unit and the charging capacitor and is used for outputting lifting voltage according to the charging current;
wherein the first comparison input voltage is equal to a sum of the charging voltage and the boosting voltage.
3. The control circuit according to claim 2, wherein the delay compensation unit includes a compensation resistor, a first end of the compensation resistor is connected to the charging current acquisition unit, and a second end of the compensation resistor is grounded via the charging capacitor;
the first end of the compensation resistor is also electrically connected with the first input end of the comparison module;
the resistance of the compensation resistor is positively correlated with the inherent delay time of the comparison module, and the resistance of the compensation resistor is negatively correlated with the capacitance of the charging capacitor.
4. The control circuit of claim 2, wherein the first comparison input module further comprises:
the charging control switch is connected with the charging capacitor in parallel, the control end of the charging control switch is electrically connected with the output end of the comparison module, and the charging control switch is used for resetting or maintaining the charging voltage of the charging capacitor according to the on-time control signal.
5. The control circuit of claim 1, wherein the second comparison input module comprises: a plurality of voltage dividing resistors connected in series;
the plurality of voltage dividing resistors include at least: the first voltage dividing resistor and the second voltage dividing resistor;
the first end of the first voltage dividing resistor is electrically connected with the output end of the switching converter, and the second end of the first voltage dividing resistor is electrically connected with the first end of the second voltage dividing resistor;
the second end of the second voltage dividing resistor is grounded;
a sampling node is arranged between the first voltage dividing resistor and the second voltage dividing resistor, the sampling node is electrically connected with the first input end of the comparison module, and the sampling node is used for outputting sampling voltage based on a preset sampling signal;
the sampling period of the preset sampling signal is equal to or approximately equal to the switching period of the switching converter.
6. A switching converter control method provided with a switching element, characterized in that it is used in a switching converter control circuit according to any one of claims 1-5, the method comprising:
acquiring the input voltage of the switching converter, and determining a first comparison input voltage according to the input voltage;
obtaining the output voltage of the switching converter, and determining a second comparison input voltage according to the output voltage;
comparing the first comparison input voltage with the second comparison input voltage, and outputting a conduction time control signal according to a voltage comparison result;
in determining a first comparison input voltage from the input voltages, the method includes:
lifting the first comparison input voltage according to the inherent delay time of the comparison module to enable the initial voltage of the first comparison input voltage to be larger than zero;
the voltage value of the initial voltage is equal to the delay trigger voltage difference value corresponding to the inherent delay time;
the delay trigger voltage difference is a voltage difference between the first comparison input voltage and the second comparison input voltage when the comparison module is triggered in a delay mode.
7. A power supply apparatus, characterized in that the power supply apparatus comprises: a dc-dc converter, and a switching converter control circuit according to any one of claims 1-5;
the DC-DC converter is provided with a switching element;
the switching converter control circuit is used for outputting a switching time control signal and controlling the switching element to be switched on or switched off according to the switching time control signal.
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| CN102097934A (en) * | 2011-02-25 | 2011-06-15 | 浙江大学 | Hysteresis mode buck DC/DC (direct current/direct current) switch converter |
| CN204119034U (en) * | 2014-04-23 | 2015-01-21 | 成都芯源系统有限公司 | Switch converter and control circuit thereof |
| US10727745B2 (en) * | 2017-07-25 | 2020-07-28 | Kinetic Technologies | Systems and methods for providing intelligent constant on-time control |
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