CN113726154A - Switching power supply control method and device and switching power supply - Google Patents
Switching power supply control method and device and switching power supply Download PDFInfo
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- CN113726154A CN113726154A CN202111022841.9A CN202111022841A CN113726154A CN 113726154 A CN113726154 A CN 113726154A CN 202111022841 A CN202111022841 A CN 202111022841A CN 113726154 A CN113726154 A CN 113726154A
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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
Abstract
The invention provides a switching power supply control method and device and a switching power supply. The method comprises the following steps: acquiring input electric parameters, output load values and energy storage inductance values of the switching power supply; calculating the duty ratio of the switching power supply according to the input electrical parameter and the output electrical parameter; and calculating the critical frequency of the switching power supply according to the duty ratio, the output load value and the energy storage inductance value, and controlling the switching power supply to work at the critical frequency so as to enable the switching power supply to work in a CRM mode. The invention can improve the working reliability of the switching power supply.
Description
Technical Field
The invention relates to the technical field of power supply control, in particular to a switching power supply control method and device and a switching power supply.
Background
With the progress of science and technology, the switching power supply is used more and more widely as a high-frequency power conversion device. The switching power supply can be classified into a Discontinuous Conduction Mode (DCM), a Continuous Conduction Mode (CCM), and a Critical Conduction Mode (CRM) according to whether the output current of the switching power supply is Continuous. Wherein, in the middle and small power occasion, the switch power supply adopting the CRM working mode has the best effect.
Currently, multipliers are mostly adopted in the prior art to control the switching power supply in the CRM operation mode. However, the control method using the multiplier is complicated, resulting in a decrease in reliability of the switching power supply.
Disclosure of Invention
The embodiment of the invention provides a switching power supply control method and device and a switching power supply, and aims to solve the problem that the reliability of the switching power supply is reduced due to the fact that a control method for controlling the switching power supply to be in a CRM (customer relationship management) working mode is complex in the prior art.
In a first aspect, an embodiment of the present invention provides a switching power supply control method, including:
acquiring input electric parameters, output load values and energy storage inductance values of the switching power supply;
calculating the duty ratio of the switching power supply according to the input electrical parameter and the output electrical parameter;
and calculating the critical frequency of the switching power supply according to the duty ratio, the output load value and the energy storage inductance value, and controlling the switching power supply to work at the critical frequency so as to enable the switching power supply to work in a CRM mode.
In one possible implementation, before calculating the duty cycle of the switching power supply according to the input electrical parameter and the output electrical parameter, the method further includes:
judging the power type of the switching power supply according to the input electric parameter and the output electric parameter; the power types include a step-up power or a step-down power.
In one possible implementation, the input electrical parameter comprises an input voltage and the output electrical parameter comprises an output voltage;
the power type of the switching power supply is judged according to the input electric parameters and the output electric parameters, and the method comprises the following steps:
when the ratio of the input voltage to the output voltage is not greater than a preset ratio, judging that the power type of the switching power supply is a boosting power supply;
and when the ratio of the input voltage to the output voltage is greater than a preset ratio, judging that the power type of the switching power supply is a step-down power supply.
In one possible implementation, the input electrical parameter comprises an input voltage and the output electrical parameter comprises an output voltage;
calculating the duty ratio of the switching power supply according to the input electrical parameter and the output electrical parameter, comprising:
when the power type is a boosting power supply, calculating the boosting duty ratio of the switching power supply according to the input voltage and the output voltage;
and when the power type is a step-down power supply, calculating the step-down duty ratio of the switching power supply according to the input voltage and the output voltage.
In one possible implementation, calculating the critical frequency of the switching power supply according to the duty ratio, the output load value and the energy storage inductance value includes:
when the power type is a boosting power supply, calculating the boosting critical frequency of the switching power supply according to a boosting duty ratio, an output load value, an energy storage inductance value and a boosting critical frequency calculation formula;
and when the power type is a step-down power supply, calculating the step-down critical frequency of the switching power supply according to the step-down duty ratio, the output load value, the energy storage inductance value and a step-down critical frequency calculation formula.
In one possible implementation, the boost critical frequency calculation formula is:
wherein f isuThe voltage is the critical voltage boosting frequency, R is an output load value, L is an energy storage inductance value, and Du is a voltage boosting duty ratio;
the calculation formula of the decompression critical frequency is as follows:
wherein f isdFor lowering the critical frequency, DdIs the buck duty cycle.
In a second aspect, an embodiment of the present invention provides a switching power supply control apparatus, including:
the parameter acquisition module is used for acquiring input electric parameters, output load values and energy storage inductance values of the switching power supply;
the duty ratio calculation module is used for calculating the duty ratio of the switching power supply according to the input electric parameters and the output electric parameters;
and the frequency adjusting module is used for calculating the critical frequency of the switching power supply according to the duty ratio, the output load value and the energy storage inductance value and controlling the switching power supply to work at the critical frequency so as to enable the switching power supply to work in a CRM mode.
In a third aspect, an embodiment of the present invention provides a terminal, including a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor executes the computer program to implement the steps of the switching power supply control method according to the first aspect or any possible implementation manner of the first aspect.
In a fourth aspect, an embodiment of the present invention provides a switching power supply, including the terminal, the switching tube, the freewheeling diode, the energy storage inductor and the capacitor as described in the third aspect; the capacitor is used for being connected with the output load;
the input end of the switching tube is connected with an external input power supply, the output end of the switching tube is respectively connected with the cathode of the fly-wheel diode and the first end of the energy storage inductor, and the control end of the switching tube is connected with the terminal;
the first end of the capacitor is connected with the second end of the energy storage inductor, and the second end of the capacitor is connected with the anode of the fly-wheel diode; the second end of the capacitor is also used for grounding; alternatively, the first and second electrodes may be,
the input end of the switching tube is respectively connected with the second end of the energy storage inductor and the anode of the fly-wheel diode, the output end of the switching tube is connected with the second end of the capacitor, and the control end of the switching tube is used for being connected with the terminal; the second end of the switch tube is also used for grounding;
the first end of the energy storage inductor is used for being connected with an external input power supply;
the first end of the capacitor is connected to the cathode of the freewheeling diode.
In a fifth aspect, an embodiment of the present invention provides a computer-readable storage medium, where a computer program is stored, and when the computer program is executed by a processor, the steps of the switching power supply control method according to the first aspect or any one of the possible implementation manners of the first aspect are implemented.
The embodiment of the invention provides a switching power supply control method, a device and a switching power supply, wherein input electric parameters, output electric parameters, an output load value and an energy storage inductance value of the switching power supply are obtained; calculating the duty ratio of the switching power supply according to the input electrical parameter and the output electrical parameter; and calculating the critical frequency of the switching power supply according to the duty ratio, the output load value and the energy storage inductance value, and controlling the switching power supply to work at the critical frequency so as to enable the switching power supply to work in a CRM mode. The method comprises the steps of firstly calculating the duty ratio, then calculating the critical frequency according to the duty ratio, the output load value and the energy storage inductance value, and finally adjusting the frequency of the switching power supply to work in a critical frequency state.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
Fig. 1 is a flowchart of an implementation of a switching power supply control method according to an embodiment of the present invention;
fig. 2 is a schematic circuit diagram of a switching power supply of which the power supply type is a boost power supply according to an embodiment of the present invention;
fig. 3 is a schematic diagram illustrating a variation of a parameter of an energy storage inductor of a switching power supply with a boost power supply according to an embodiment of the present invention;
fig. 4 is a schematic circuit diagram of a switching power supply with a step-down power supply according to an embodiment of the present invention;
fig. 5 is a schematic diagram illustrating a current variation of an energy storage inductor of a switching power supply with a step-down power supply according to an embodiment of the present invention;
fig. 6 is a schematic diagram illustrating a variation of a parameter of an energy storage inductor of a switching power supply with a step-down power supply according to an embodiment of the present invention;
FIG. 7 is a diagram illustrating simulation results after frequency adjustment according to an embodiment of the present invention;
FIG. 8 is a diagram illustrating simulation results when output load changes according to an embodiment of the present invention;
fig. 9 is a schematic structural diagram of a switching power supply control device according to an embodiment of the present invention;
fig. 10 is a schematic diagram of a terminal according to an embodiment of the present invention.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the following description is made by way of specific embodiments with reference to the accompanying drawings.
Referring to fig. 1, it shows a flowchart of an implementation of the switching power supply control method provided in the embodiment of the present invention. As shown in fig. 1, a switching power supply control method may include:
and S101, acquiring input electric parameters, output load values and energy storage inductance values of the switching power supply.
Optionally, each parameter is a parameter obtained when the switching power supply operates in a steady state. The input electrical parameter of the switching power supply may comprise an input voltage or an input current and the output electrical parameter may comprise an output voltage or an output current. The output load of the switching power supply is generally a capacitive load, the output load value can be directly obtained, and the energy storage inductance value is determined when the switching power supply is designed.
Optionally, the input electrical parameter, the output load value and the energy storage inductance value may all be parameters of the switching power supply working at a first preset frequency; the first preset frequency is the frequency of the switching power supply working in a CCM mode; the switching power supply stably works in a CCM mode at a first preset frequency, so that the feedback compensation of a control loop of the switching power supply is easy, the transient response caused by sudden change of load current is faster, the dynamic is good, and the overshoot is lower.
Optionally, the input electrical parameter, the output load value and the energy storage inductance value may also be parameters of the switching power supply working at a second preset frequency; the second preset frequency is the frequency of the switching power supply working in the DCM; the switching power supply works in a DCM mode at a second preset frequency, and is suitable for occasions with large load current changes.
And S102, calculating the duty ratio of the switching power supply according to the input electric parameter and the output electric parameter.
Optionally, the duty ratio is a modulation degree of the pulse width modulation switching power supply, a voltage stabilizing function of the switching power supply can be achieved by automatically changing the duty ratio, and the duty ratio represents a ratio of conduction time to a working period of the switching tube. As can be expressed as:
where D is the duty cycle of the switching power supply, TonThe on-time of the switching tube is T, and the working period of the switching power supply is T.
And S103, calculating the critical frequency of the switching power supply according to the duty ratio, the output load value and the energy storage inductance value, and controlling the switching power supply to work at the critical frequency so as to enable the switching power supply to work in a CRM mode.
Optionally, calculating a critical frequency of the switching power supply according to the duty ratio, the output load value and the energy storage inductance value, and controlling the switching power supply to switch from a first preset frequency to the critical frequency to work so that the switching power supply is switched from a CCM mode to a CRM mode;
optionally, the critical frequency of the switching power supply is calculated according to the duty ratio, the output load value and the energy storage inductance value, and the switching power supply is controlled to be switched from the second preset frequency to the critical frequency to work, so that the switching power supply is switched from the DCM mode to the CRM mode.
Alternatively, the switching frequency of the switching power supply is the number of times that the signal goes from high level to low level and back to high level every second. The critical frequency is a switching frequency at which the switching power supply can operate in the CRM mode. Generally, the switching frequency of the switching power supply operating in the steady state needs to be adjusted to the critical frequency, or gradually adjusted to the critical frequency, so that the switching power supply operates in the CRM mode. And when the device works in the CRM mode, the device stress which is not as large as that of the discontinuous conduction mode is avoided, the problem of diode reverse recovery which is caused by the continuous conduction mode is also solved, and the input average current and the input voltage are in a linear relation. In the occasion of medium and small power, the power factor correction in the CRM mode has a great advantage.
Optionally, in general, a first time period is required for the switching power supply to work in a steady state from the start-up, a second time period is required for the switching power supply to adjust from the steady state to the CRM mode, and the first time period and the second time period are both very short, so that the normal use of the switching power supply is not affected. Therefore, the switching power supply can work in a stable state firstly and then is adjusted to the CRM mode from the stable state, so that the stable control of the switching power supply is facilitated, and the control stability of the switching power supply is enhanced.
For example, in addition to directly controlling the operation of the switching power supply at the critical frequency, the switching power supply may have four operation processes:
the first method comprises the following steps: the switching power supply can start working at a first preset frequency, the duty ratio of the switching power supply is controlled according to the conventional PWM, the output voltage of the switching power supply reaches a preset target value, after the switching power supply reaches a CCM mode stable state, the critical frequency of the switching power supply is calculated, and the first preset frequency is adjusted to the critical frequency, so that the switching power supply is adjusted to a CRM mode from the CCM mode, and the switching power supply works at the optimal efficiency.
And the second method comprises the following steps: the switching power supply can start working at a first preset frequency, the duty ratio of the switching power supply is controlled according to conventional PWM, the output voltage of the switching power supply reaches a preset target value, after the switching power supply reaches a CCM mode stable state, the critical frequency of the switching power supply is calculated, the first preset frequency is adjusted to be close to the critical frequency, the switching power supply is enabled to be close to a CRM mode from the CCM mode, the efficiency of the switching power supply can be higher due to the fact that the switching power supply is close to the CRM mode from the CCM mode, the switching power supply can work at a better efficiency, the efficiency is higher when the switching power supply is close to the CRM mode, and the working performance is better.
And the third is that: the switching power supply can start working at a second preset frequency, the duty ratio of the switching power supply is controlled according to the conventional PWM, the output voltage of the switching power supply reaches a preset target value, after the switching power supply reaches a DCM (discontinuous conduction mode) steady state, the critical frequency of the switching power supply is calculated, and the second preset frequency is adjusted to the critical frequency, so that the switching power supply is adjusted to a CRM (customer relationship management) mode from a CCM (continuous current mode) mode.
And fourthly: the switching power supply can start working at a second preset frequency, the duty ratio of the switching power supply is controlled according to the conventional PWM, the output voltage of the switching power supply reaches a preset target value, after the switching power supply reaches a DCM mode steady state, the critical frequency of the switching power supply is calculated, and the second preset frequency is adjusted to be close to the critical frequency, so that the switching power supply is close to a CRM mode from the DCM mode.
In terms of performance, the work performance of the switching power supply working in the CRM mode is optimal, and the work performance of the switching power supply approaching from the CCM mode to the CRM mode is better than that of the switching power supply approaching from the DCM mode to the CRM mode. Namely, the working performance of the switching power supply is as follows: first > third > second > fourth. In practical application, the CCM mode is suitable for a high-power switching power supply, the DCM mode is suitable for a medium-low power switching power supply, and the working process of the switching power supply can be specifically selected according to the type of the switching power supply.
According to the embodiment of the invention, the input electric parameter, the output load value and the energy storage inductance value of the switching power supply are obtained; calculating the duty ratio of the switching power supply according to the input electrical parameter and the output electrical parameter; and calculating the critical frequency of the switching power supply according to the duty ratio, the output load value and the energy storage inductance value, and controlling the switching power supply to work at the critical frequency so as to enable the switching power supply to work in a CRM mode. The method comprises the steps of firstly calculating the duty ratio, then calculating the critical frequency according to the duty ratio, the output load value and the energy storage inductance value, and finally adjusting the frequency of the switching power supply to work in a critical frequency state.
In some embodiments of the invention, prior to calculating the duty cycle of the switching power supply from the input electrical parameter and the output electrical parameter, the method further comprises:
judging the power type of the switching power supply according to the input electric parameter and the output electric parameter; the power types include a step-up power or a step-down power.
Alternatively, the switching power supply may include a switching power supply of which power supply type is a step-up power supply or a switching power supply of which power supply type is a step-down power supply. The switching power supply with the power type of the boost power supply is the boost power supply, and the output voltage of the boost power supply is generally not less than the input voltage. The switching power supply with the power type of the buck power supply is the buck voltage-reducing power supply, and the output voltage of the buck voltage-reducing power supply is generally smaller than the input voltage.
In some embodiments of the invention, the input electrical parameter comprises an input voltage and the output electrical parameter comprises an output voltage;
the power type of the switching power supply is judged according to the input electric parameters and the output electric parameters, and the method comprises the following steps:
when the ratio of the input voltage to the output voltage is not greater than a preset ratio, judging that the power type of the switching power supply is a boosting power supply;
and when the ratio of the input voltage to the output voltage is greater than a preset ratio, judging that the power type of the switching power supply is a step-down power supply.
Alternatively, the preset ratio may be 1.
Optionally, when the input voltage is not greater than the output voltage, determining that the power type of the switching power supply is a boost power supply; and when the input voltage is greater than the output voltage, judging that the power type of the switching power supply is a step-down power supply.
In some embodiments of the invention, the input electrical parameter comprises an input voltage and the output electrical parameter comprises an output voltage; calculating the duty ratio of the switching power supply according to the input electrical parameter and the output electrical parameter, comprising:
when the power type is a boosting power supply, calculating the boosting duty ratio of the switching power supply according to the input voltage and the output voltage; and when the power type is a step-down power supply, calculating the step-down duty ratio of the switching power supply according to the input voltage and the output voltage.
Optionally, for a switching power supply of which the power supply type is a boost power supply, a formula for calculating a boost duty cycle of the switching power supply according to the input voltage and the output voltage is as follows:
wherein D isuTo boost the duty cycle, VgFor input voltage, VoIs the output voltage.
For the switching power supply with the power type of a step-down power supply, a formula for calculating the step-down duty ratio of the switching power supply according to the input voltage and the output voltage is as follows:
wherein D isdIs the buck duty cycle.
In some embodiments of the present invention, calculating the critical frequency of the switching power supply according to the duty cycle, the output load value and the energy storage inductance value comprises:
when the power type is a boosting power supply, calculating the boosting critical frequency of the switching power supply according to a boosting duty ratio, an output load value, an energy storage inductance value and a boosting critical frequency calculation formula;
and when the power type is a step-down power supply, calculating the step-down critical frequency of the switching power supply according to the step-down duty ratio, the output load value, the energy storage inductance value and a step-down critical frequency calculation formula.
In some embodiments of the present invention, the boost critical frequency calculation formula is:
wherein f isuThe voltage is the critical voltage boosting frequency, R is an output load value, L is an energy storage inductance value, and Du is a voltage boosting duty ratio;
the calculation formula of the decompression critical frequency is as follows:
wherein f isdFor lowering the critical frequency, DdIs the buck duty cycle.
Optionally, referring to fig. 2, a schematic diagram of a circuit structure of a power supply type that is a boost power supply according to an embodiment of the present invention is shown. As shown in fig. 2, the boost power supply may include an energy storage inductor L1, a switching tube S, a freewheeling diode D1, and a capacitor C, Vg being the input voltage, Vo being the output voltage, and R1 being the output load.
Referring to fig. 3, it shows a schematic diagram of parameter variation of an energy storage inductor of a boost power supply as a power supply type provided by an embodiment of the present invention. As shown in FIG. 3, ILPIs the peak current of the energy storage inductor L1, Ig is the input current, DTs is the conduction duration of the switching tube, Ts is the working period of the switching tube, IL(t)Is the current variation waveform V of the energy storage inductor along with the time tL(t)The Vgs is the variation waveform of the input voltage, and is the voltage conversion waveform of the energy storage inductor along with the time t.
The determination of the boost threshold frequency calculation formula is described with reference to fig. 2 and 3:
if a switching power supply (i.e., a Boost power supply) with a power type of a Boost power supply is to operate in a CRM mode, the precondition is that the average value of the energy storage inductor current is equal to the average value Io of the output current:
step 1: calculating the peak current I of the energy storage inductorLP：
By
The following can be obtained: i isLP＝(Vg*Du*Ts)/L。
Step 2: calculating the relation between the output average current and the energy storage inductance current: for the energy storage inductor of the switching power supply with the power type being the boost power supply, when the switching tube is turned on, the current of the energy storage inductor does not flow into the output load, and when only the switching tube is turned off, the current of the energy storage inductor passes through the output load, so that the output average current is:
and step 3: calculating the identity relation under the critical condition: io ═ Vo/R，
And 4, step 4: according to the formulas of the step 1 to the step 3, the following can be obtained:
order:
then there are:
when D is presentu(1-Du)2＝KcritWhen the power supply is the boost power supply, the switch power supply is in a CRM mode (namely a CCM/DCM boundary);
when D is presentu(1-Du)2＜KcritWhen the power supply is a boosting power supply, the switching power supply is in a CCM mode;
when D is presentu(1-Du)2＞KcritWhen the power supply type is the boost power supply, the switching power supply is in the DCM mode.
By reverse reasoning, one can obtain:
when in use
When the power supply is a boosting power supply, the switching power supply works in a CRM mode;
when in use
When the power supply is a boost power supply, the switching power supply works in a DCM mode;
when in use
In the meantime, the switching power supply of which the power supply type is the booster power supply operates in the CCM mode.
Optionally, referring to fig. 4, a schematic diagram of a circuit structure of a power supply of a step-down power supply according to an embodiment of the present invention is shown. As shown in fig. 4, the step-down power supply may include an energy storage inductor L1, a switching tube S, a freewheeling diode D1, and a capacitor C, Vg being the input voltage, Vo being the output voltage, and R1 being the output load.
Referring to fig. 5, a schematic diagram of a current variation of an energy storage inductor of a boost power supply according to an embodiment of the present invention is shown. Referring to fig. 6, a schematic diagram of parameter variation of an energy storage inductor of a step-down power supply according to an embodiment of the present invention is shown.
The calculation formula for determining the depressurization critical frequency is described with reference to fig. 4, 5 and 6:
from fig. 4 and 5, it can be seen that:
when the switching power supply with the power type of the step-down power supply works in the CRM mode, the current flowing through the energy storage inductor is just continuous and is in a critical state, and the method comprises the following steps:
d+d'+d*＝1，d*＝0；
when the switching power supply with the power type of the step-down power supply works in the CCM mode, the current flowing through the energy storage inductor is continuous, and the method comprises the following steps:
d+d'+d*＝1，d*＝0；
when the switching power supply with the power type of the step-down power supply works in the DCM mode, dT represents that the current flowing through the energy storage inductor is discontinuoussFor the off time, there are:
d+d'+d*＝1，d*≠0；
wherein d is*0 is the time during which the current is zero in one duty cycle, d*Not equal to 0 is that the time during which the current is zero in one duty cycle is not zero.
From FIG. 6, it can be seen that:
the above formula is simplified, and the simplification process is as follows:
available K-1-DdWherein, in the step (A),
then it is possible to obtain:
when K is 1-DdWhen the power supply is a buck power supply, the switch power supply is in a CRM mode (namely a CCM/DCM boundary);
when K is>1-DdWhen the power supply is in a CCM mode, the switching power supply with the type of the voltage reduction power supply is adopted;
when K is<1-DdWhen the power supply type is the buck power supply, the switching power supply is in the DCM mode.
By reverse-pushing, the critical frequency of depressurization can be obtained:
when in use
And meanwhile, the switching power supply with the power type being the step-down power supply works in the CRM mode.
Referring to fig. 7, a schematic diagram of a simulation result after frequency adjustment according to an embodiment of the present invention is shown; FIG. 7(a) is a diagram illustrating the overall simulation results of the output voltage, the current of the energy storage inductor and the voltage of the switching tube; fig. 7(b) is a schematic diagram of a partial simulation result of the output voltage, the current of the energy storage inductor and the voltage of the switching tube.
Illustratively, for a switching power supply in which one power supply type is a step-down power supply,the output load value is 5 omega hm, the inductance value of the energy storage inductor is 85uh, the output voltage is 200V, the input voltage is 532V, and the voltage reduction duty ratio D is obtained through calculation d200/532, and calculating the critical frequency of voltage reduction
From the simulation result of fig. 7, it can be seen that the switching frequency is adaptive to 18.5kHz in the steady state, which is close to the theoretical calculation value, and it can be seen that the CRM control is realized by the inductor current, and the output voltage ripple is within 2V.
Referring to fig. 8, a schematic diagram of a simulation result when an output load changes according to an embodiment of the present invention is shown; FIG. 8(a) is a diagram illustrating the overall simulation results of the output voltage, the current of the energy storage inductor, and the voltage of the switching tube; fig. 8(b) is a schematic diagram of a partial simulation result of the output voltage, the current of the energy storage inductor and the voltage of the switching tube.
As can be seen from the simulation of fig. 8, the switching power supply includes a slow-up of the switching power supply within 0-0.02 s, a sudden unloading of about 0.04s, and a sudden loading condition of about 0.06 s: the voltage overshoots to 207V when the load is suddenly removed, and drops to about 187V when the load is suddenly removed.
The embodiment of the invention can clearly control the working point when the switching power supply is in a stable state, and can accurately and reliably make the switching power supply work in a critical frequency state (namely make the switching power supply work in a CRM mode), thereby reducing the stress borne by the switching device, prolonging the service life of the device and achieving the effect of improving the working reliability of the switching power supply.
It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.
The following are embodiments of the apparatus of the invention, reference being made to the corresponding method embodiments described above for details which are not described in detail therein.
Fig. 9 is a schematic structural diagram of a switching power supply control device according to an embodiment of the present invention, and for convenience of description, only the parts related to the embodiment of the present invention are shown, and detailed descriptions are as follows:
as shown in fig. 9, the switching power supply control device 20 may include:
the parameter acquiring module 201 is configured to acquire an input electrical parameter, an output load value, and an energy storage inductance value of the switching power supply;
a duty ratio calculation module 202, configured to calculate a duty ratio of the switching power supply according to the input electrical parameter and the output electrical parameter;
and the frequency adjusting module 203 is configured to calculate a critical frequency of the switching power supply according to the duty ratio, the output load value, and the energy storage inductance value, and control the switching power supply to operate at the critical frequency, so that the switching power supply operates in the CRM mode.
In some embodiments of the present invention, the switching power supply control device 20 may include:
the type judging module is used for judging the power type of the switching power supply according to the input electric parameter and the output electric parameter before calculating the duty ratio of the switching power supply according to the input electric parameter and the output electric parameter; the power types include a step-up power or a step-down power.
In some embodiments of the invention, the input electrical parameter comprises an input voltage and the output electrical parameter comprises an output voltage; the type judging module may include:
the first judging unit is used for judging the power type of the switching power supply to be a boosting power supply when the ratio of the input voltage to the output voltage is not greater than a preset ratio;
and the second judging unit is used for judging the power type of the switching power supply to be a step-down power supply when the ratio of the input voltage to the output voltage is greater than the preset ratio.
In some embodiments of the invention, the input electrical parameter comprises an input voltage and the output electrical parameter comprises an output voltage; a duty cycle calculation module, which may include:
the first calculating unit is used for calculating the boosting duty ratio of the switching power supply according to the input voltage and the output voltage when the power supply type is a boosting power supply;
and the second calculating unit is used for calculating the voltage reduction duty ratio of the switching power supply according to the input voltage and the output voltage when the power supply type is the voltage reduction power supply.
In some embodiments of the present invention, the frequency adjustment module 203 may include:
the third calculating unit is used for calculating the boosting critical frequency of the switching power supply according to the boosting duty ratio, the output load value, the energy storage inductance value and the boosting critical frequency calculating formula when the power supply type is the boosting power supply;
and the fourth calculating unit is used for calculating the voltage reduction critical frequency of the switching power supply according to the voltage reduction duty ratio, the output load value, the energy storage inductance value and the voltage reduction critical frequency calculating formula when the power type is the voltage reduction power supply.
In some embodiments of the present invention, the boost critical frequency calculation formula is:
wherein f isuThe voltage is the critical voltage boosting frequency, R is an output load value, L is an energy storage inductance value, and Du is a voltage boosting duty ratio;
the calculation formula of the decompression critical frequency is as follows:
wherein f isdFor lowering the critical frequency, DdIs the buck duty cycle.
Fig. 10 is a schematic diagram of a terminal according to an embodiment of the present invention. As shown in fig. 10, the terminal 30 of this embodiment includes: a processor 300, a memory 301, and a computer program 302 stored in the memory 301 and executable on the processor 300. The steps in the various switching power supply control method embodiments described above, such as S101 to S103 shown in fig. 1, are implemented when the processor 300 executes the computer program 302. Alternatively, the processor 300, when executing the computer program 302, implements the functions of the modules/units in the above-described device embodiments, such as the functions of the modules/units 201 to 203 shown in fig. 9.
Illustratively, the computer program 302 may be partitioned into one or more modules/units, which are stored in the memory 301 and executed by the processor 300 to implement the present invention. One or more of the modules/units may be a series of computer program instruction segments capable of performing specific functions, which are used to describe the execution of the computer program 302 in the terminal 30. For example, the computer program 302 may be divided into the modules/units 201 to 203 shown in fig. 9.
The terminal 30 may be a desktop computer, a notebook, a palm computer, a cloud server, or other computing devices. The terminal 30 may include, but is not limited to, a processor 300, a memory 301. Those skilled in the art will appreciate that fig. 10 is merely an example of a terminal 30 and does not constitute a limitation of terminal 30 and may include more or fewer components than shown, or some of the components may be combined, or different components, e.g., the terminal may also include input-output devices, network access devices, buses, etc.
The Processor 300 may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The storage 301 may be an internal storage unit of the terminal 30, such as a hard disk or a memory of the terminal 30. The memory 301 may also be an external storage device of the terminal 30, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), and the like provided on the terminal 30. Further, the memory 301 may also include both internal storage units of the terminal 30 and external storage devices. The memory 301 is used to store computer programs and other programs and data required by the terminal. The memory 301 may also be used to temporarily store data that has been output or is to be output.
It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-mentioned division of the functional units and modules is illustrated, and in practical applications, the above-mentioned function distribution may be performed by different functional units and modules according to needs, that is, the internal structure of the apparatus is divided into different functional units or modules, so as to perform all or part of the functions described above. Each functional unit and module in the embodiments may be integrated in one processing unit, or each unit may exist alone physically, or two or more units are integrated in one unit, and the integrated unit may be implemented in a form of hardware, or in a form of software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working processes of the units and modules in the system may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
The embodiment of the invention also provides a switching power supply, which comprises the terminal 30, a switching tube, a freewheeling diode, an energy storage inductor and a capacitor; the capacitor is used for being connected with the output load;
the input end of the switching tube is connected with an external input power supply, the output end of the switching tube is respectively connected with the cathode of the fly-wheel diode and the first end of the energy storage inductor, and the control end of the switching tube is connected with the terminal; the first end of the capacitor is connected with the second end of the energy storage inductor, and the second end of the capacitor is connected with the anode of the fly-wheel diode; the second end of the capacitor is also used for grounding; alternatively, the first and second electrodes may be,
the input end of the switching tube is respectively connected with the second end of the energy storage inductor and the anode of the fly-wheel diode, the output end of the switching tube is connected with the second end of the capacitor, and the control end of the switching tube is used for being connected with the terminal; the second end of the switch tube is also used for grounding; the first end of the energy storage inductor is used for being connected with an external input power supply; the first end of the capacitor is connected to the cathode of the freewheeling diode.
Optionally, both ends of the capacitor are further used for connecting with an external load.
In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the embodiments provided in the present invention, it should be understood that the disclosed apparatus/terminal and method may be implemented in other ways. For example, the above-described apparatus/terminal embodiments are merely illustrative, and for example, a module or a unit may be divided into only one logical function, and may be implemented in other ways, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
Units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated modules/units, if implemented in the form of software functional units and sold or used as separate products, may be stored in a computer readable storage medium. Based on such understanding, all or part of the flow in the method according to the above embodiments may be implemented by a computer program, which may be stored in a computer readable storage medium and used by a processor to implement the steps of the above embodiments of the switching power supply control method. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer readable medium may include: any entity or device capable of carrying computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, and the like. It should be noted that the computer readable medium may include any suitable increase or decrease as required by legislation and patent practice in the jurisdiction, for example, in some jurisdictions, computer readable media may not include electrical carrier signals and telecommunications signals in accordance with legislation and patent practice.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.
Claims (10)
1. A switching power supply control method, comprising:
acquiring input electric parameters, output load values and energy storage inductance values of the switching power supply;
calculating the duty ratio of the switching power supply according to the input electrical parameter and the output electrical parameter;
and calculating the critical frequency of the switching power supply according to the duty ratio, the output load value and the energy storage inductance value, and controlling the switching power supply to work at the critical frequency so as to enable the switching power supply to work in a CRM mode.
2. The switching power supply control method according to claim 1, wherein before calculating the duty cycle of the switching power supply from the input electrical parameter and the output electrical parameter, the method further comprises:
judging the power type of the switching power supply according to the input electrical parameter and the output electrical parameter; the power supply type includes a step-up power supply or a step-down power supply.
3. The switching power supply control method according to claim 2, wherein the input electrical parameter comprises an input voltage, and the output electrical parameter comprises an output voltage;
the judging the power type of the switching power supply according to the input electrical parameter and the output electrical parameter comprises the following steps:
when the ratio of the input voltage to the output voltage is not greater than a preset ratio, determining that the power type of the switching power supply is a boosting power supply;
and when the ratio of the input voltage to the output voltage is greater than the preset ratio, determining that the power type of the switching power supply is a step-down power supply.
4. The switching power supply control method according to claim 2, wherein the input electrical parameter comprises an input voltage, and the output electrical parameter comprises an output voltage;
the calculating the duty ratio of the switching power supply according to the input electrical parameter and the output electrical parameter comprises:
when the power type is a boosting power supply, calculating the boosting duty ratio of the switching power supply according to the input voltage and the output voltage;
and when the power type is a step-down power supply, calculating the step-down duty ratio of the switching power supply according to the input voltage and the output voltage.
5. The method according to claim 4, wherein the calculating the critical frequency of the switching power supply according to the duty cycle, the output load value and the energy storage inductance value comprises:
when the power type is a boosting power supply, calculating the boosting critical frequency of the switching power supply according to the boosting duty ratio, the output load value, the energy storage inductance value and a boosting critical frequency calculation formula;
and when the power type is a step-down power supply, calculating the step-down critical frequency of the switching power supply according to the step-down duty ratio, the output load value, the energy storage inductance value and a step-down critical frequency calculation formula.
6. The switching power supply control method according to claim 5, wherein the boost critical frequency calculation formula is:
wherein f isuThe step-up critical frequency, R is the output load value, L is the energy storage inductance value, and Du is the step-up duty cycle;
the calculation formula of the depressurization critical frequency is as follows:
wherein f isdIs the reduced critical frequency, DdIs the buck duty cycle.
7. A switching power supply control device characterized by comprising:
the parameter acquisition module is used for acquiring input electric parameters, output load values and energy storage inductance values of the switching power supply;
the duty ratio calculation module is used for calculating the duty ratio of the switching power supply according to the input electrical parameter and the output electrical parameter;
and the frequency adjusting module is used for calculating the critical frequency of the switching power supply according to the duty ratio, the output load value and the energy storage inductance value and controlling the switching power supply to work at the critical frequency so as to enable the switching power supply to work in a CRM mode.
8. A terminal comprising a memory, a processor and a computer program stored in said memory and executable on said processor, characterized in that said processor implements the steps of the switching power supply control method according to any one of the preceding claims 1 to 6 when executing said computer program.
9. A switching power supply comprising a terminal as claimed in claim 8, a switching tube, a freewheeling diode, an energy storage inductor and a capacitor; the capacitor is used for being connected with an output load;
the input end of the switch tube is connected with an external input power supply, the output end of the switch tube is respectively connected with the cathode of the fly-wheel diode and the first end of the energy storage inductor, and the control end of the switch tube is connected with the terminal; the first end of the capacitor is connected with the second end of the energy storage inductor, and the second end of the capacitor is connected with the anode of the freewheeling diode; the second end of the capacitor is also used for grounding; alternatively, the first and second electrodes may be,
the input end of the switching tube is respectively connected with the second end of the energy storage inductor and the anode of the fly-wheel diode, the output end of the switching tube is connected with the second end of the capacitor, and the control end of the switching tube is connected with the terminal; the output end of the switching tube is also used for grounding; the first end of the energy storage inductor is used for being connected with an external input power supply; the first end of the capacitor is connected with the cathode of the freewheeling diode.
10. A computer-readable storage medium, in which a computer program is stored, which, when being executed by a processor, carries out the steps of the switching power supply control method according to any one of claims 1 to 6 above.
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