CN115864853A - Trough latching and switching control circuit and control method based on output power - Google Patents
Trough latching and switching control circuit and control method based on output power Download PDFInfo
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Abstract
The invention relates to the technical field of switching power supply control, and particularly discloses a trough latching and switching control circuit and a trough latching and switching control method based on output power, wherein the trough latching and switching control circuit comprises the following steps: acquiring an output voltage detection signal and an output current detection signal of a switching power supply; calculating to obtain an output voltage detection value of the switching power supply according to an output voltage detection signal of the switching power supply, and calculating to obtain an output current detection value of the switching power supply according to an output current detection signal of the switching power supply; calculating to obtain an output power detection value of the switching power supply according to the output voltage detection value and the output current detection value of the switching power supply; comparing the output power detection value of the switching power supply with a preset trough switching power threshold value, and outputting a comparison result; and switching the opening point of the power switch tube from the currently locked wave trough to the corresponding target wave trough according to the comparison result. The invention can optimize the efficiency of the flyback converter, improve the power density and reduce the system cost.
Description
Technical Field
The invention relates to the technical field of switching power supply control, in particular to a trough latching and switching control circuit based on output power and a trough latching and switching control method based on output power.
Background
The flyback converter is widely used for various consumer electronics products and is a main topology of a medium and small power supply. The scheme of high efficiency, low noise is to reducing system cost, improves user experience and is very important. Fig. 1 is a schematic diagram of a typical flyback converter circuit. Wherein the input is AC alternating voltage, and C1 is the filter capacitor after the input voltage is rectified. And Q1 is a primary side main switching tube. The transformer T1 has a primary winding Np, a secondary winding Ns, and an auxiliary winding Na. D1 is an output rectifier. The controller derives a supply VCC from the auxiliary winding Na supplied through the rectifier D2. The controller outputs a signal DRV to drive the switching tube Q1 to be switched on and off. When Q1 is on, the transformer T1 stores energy from the input. When the switching tube Q1 is turned off, the transformer T1 releases energy to the output terminal. The control circuit can acquire the working voltage information of the transformer T1 by detecting the signal of the auxiliary winding Na to the pin ZCD. The controller obtains the operating current information of Q1 by detecting Rcs voltage to pin CS. The FB voltage is a feedback loop output to control the output voltage or current.
In the flyback circuit, the proportion of the switching loss of the switching tube Q1 to the total system loss is high. In order to improve efficiency, the quasi-resonance control method enables the Q1 to be switched on when the drain voltage Vdrain resonates to the lowest point, so that loss is reduced. As shown in fig. 2, in the first period, when the drain voltage Vdrain of Q1 reaches the first trough t1 of the resonant period, the next DRV signal drives Q1 to turn on. However, the valley time varies with the operating state of the power supply itself, and its related factors include input voltage, output power, circuit parameters, etc. Therefore, if no control is performed, the number of troughs of the Q1 on point will change, and as shown in fig. 2, the trough on time t2 is located at the third trough in the second period. Uncontrolled variations in the number of valleys can cause audible noise and reduced efficiency, which is detrimental for high frequency, small volume applications. Therefore, in a state where the load is constant or the variation is small, it is desirable to maintain the number of troughs constant and to maintain the frequency substantially constant.
The feedback signal FB decreases with decreasing output power, and therefore, the conventional latch valley manner is performed according to the value of the feedback signal FB. As shown in fig. 3, when FB is lower than the preset threshold, the number of troughs is increased according to a predetermined control method; when FB increases above a preset threshold, the number of troughs is reduced according to a preset control method. A return difference is provided between the increasing and decreasing thresholds. The method can realize valley latch for common flyback power conversion, but has difficulty in flyback conversion which needs to control power output, especially constant power output, or requires full load power larger than nominal power. These 2 power outputs are shown in figure 4. Under the condition of constant power output, the output power of the working point A is equal to that of the working point C. However, the output voltage at point C is much lower than that at point a, so the operating frequency at point C is much lower than that at point a, and the FB voltage at point C is much higher than that at point a for the same output power requirement. In the case of high full-load power, the full-load power at point B is much higher than that at point a, and similarly, the FB voltage at point B is much higher than that at point a. The common condition of these 2 types of circuits is that at the nominal output point, because the FB voltage is far lower than the full FB voltage, the switching method of presetting the FB threshold according to the conventional trough will cause the power supply to work at a lower frequency at the nominal power, which causes the efficiency reduction and the EMI effect to be poor, which results in the reduction of the utilization rate of the flyback converter and the increase of the cost of practical application.
Disclosure of Invention
The invention provides a trough latching and switching control circuit and a trough latching and switching control method based on output power, which aim to solve the problems that the switching method of presetting an FB threshold according to the trough in the prior art can cause the reduction of efficiency and poor EMI effect due to the fact that a power supply works at a lower frequency at a nominal power, the utilization rate of a flyback converter is reduced, and the cost of practical application is increased.
As a first aspect of the present invention, there is provided a control circuit for output power based trough latching and switching, applied to a switching power supply, the switching power supply includes a rectifier bridge, a transformer T1 composed of a primary winding Np, a secondary winding Ns and an auxiliary winding Na, a power switching tube Q1, an output rectifier tube D1, a first resistor R1, a second resistor R2, a third resistor Rcs and a controller, the controller includes the control circuit for output power based trough latching and switching, the control circuit for output power based trough latching and switching includes an output voltage detection unit, an output current detection unit, a multiplier, a preset power register unit, a comparator and a trough switching execution unit, an input end of the output voltage detection unit is connected between the first resistor R1 and the second resistor R2 to obtain an output voltage detection signal of the switching power supply, an output end of the output voltage detection unit is connected to a first input end of the multiplier, an input end of the output current detection unit is connected to a source of the power switching tube Q1 and the third resistor Rcs to obtain an output voltage detection signal of the switching power supply, and an output end of the multiplier is connected to an output end of the comparator, an output end of the comparator is connected to an output end of the multiplier, and an output end of the comparator is connected to the output end of the comparator, the comparator is connected to an output end of the comparator, and an output end of the comparator, the comparator is connected to an output end of the comparator, and a negative terminal of the comparator, the comparator is connected to the comparator, the comparator is connected to the output end of the output terminal of the multiplier;
the output voltage detection unit is used for calculating an output voltage detection value Vo of the switching power supply according to the output voltage detection signal of the switching power supply;
the output current detection unit is used for calculating an output current detection value Io of the switching power supply according to an output current detection signal of the switching power supply;
the multiplier is used for calculating an output power detection value Po of the switching power supply according to an output voltage detection value Vo and an output current detection value Io of the switching power supply;
the comparator is used for comparing an output power detection value Po of the switching power supply with a trough switching power threshold value in the preset power register unit and outputting a comparison result to the trough switching execution unit;
and the wave trough switching execution unit is used for switching the opening point of the power switch tube Q1 from the currently locked wave trough to the corresponding target wave trough according to the comparison result.
Further, a calculation formula of the output voltage detection value Vo of the switching power supply is as follows:
wherein Vout is an actual value of the output voltage of the switching power supply, na is the number of turns of the auxiliary winding of the transformer T1, and Ns is the number of turns of the secondary winding of the transformer T1.
Further, the calculating the output current detection value Io of the switching power supply according to the output current detection signal of the switching power supply includes:
the calculation formula of the output current detection value Io of the switching power supply is as follows:
wherein Vcs is a peak voltage of a controller pin CS, rcs is a current sampling resistance value of the controller pin CS, np is the number of turns of a primary winding of the transformer T1, tr is a magnetic recovery time of the transformer T1, and Tp is a working period of the switching power supply.
Further, the calculation formula of the output power detection value Po of the switching power supply is as follows:
Po=Vo×Io。
the switching power supply further comprises a nominal power setting unit, wherein the nominal power setting unit is used for setting a nominal power value of the switching power supply, inquiring a corresponding trough switching power threshold value in the preset power register unit according to the set nominal power value and a preset nominal power turning point percentage, and using the corresponding trough switching power threshold value as a reference power value of the comparator;
the comparator receives the output power detection value Po of the switching power supply and the reference power value, and when the output power detection value Po of the switching power supply is increased or decreased to the reference power value, the trough switching execution unit switches the opening point of the power switching tube Q1 from the currently locked trough to the corresponding target trough.
As another aspect of the present invention, there is provided a control method for output power based trough latching and switching, applied to a switching power supply, the switching power supply includes a rectifier bridge, a transformer T1 composed of a primary winding Np, a secondary winding Ns and an auxiliary winding Na, a power switching tube Q1, an output rectifier tube D1, a first resistor R1, a second resistor R2, a third resistor Rcs and a controller, and the control method for output power based trough latching and switching includes:
step S1: acquiring an output voltage detection signal and an output current detection signal of the switching power supply;
step S2: calculating to obtain an output voltage detection value Vo of the switching power supply according to the output voltage detection signal of the switching power supply, and calculating to obtain an output current detection value Io of the switching power supply according to the output current detection signal of the switching power supply;
and step S3: calculating to obtain an output power detection value Po of the switching power supply according to an output voltage detection value Vo and an output current detection value Io of the switching power supply;
and step S4: comparing the output power detection value Po of the switching power supply with a preset wave trough switching power threshold value, and outputting a comparison result;
step S5: and switching the opening point of the power switch tube Q1 from the currently locked wave trough to the corresponding target wave trough according to the comparison result.
Further, the calculating the output voltage detection value Vo of the switching power supply according to the output voltage detection signal of the switching power supply includes:
the calculation formula of the output voltage detection value Vo of the switching power supply is as follows:
wherein Vout is an actual value of the output voltage of the switching power supply, na is the number of turns of the auxiliary winding of the transformer T1, and Ns is the number of turns of the secondary winding of the transformer T1.
Further, the calculating the output current detection value Io of the switching power supply according to the output current detection signal of the switching power supply includes:
the calculation formula of the output current detection value Io of the switching power supply is as follows:
wherein Vcs is a peak voltage of a controller pin CS, rcs is a current sampling resistance value of the controller pin CS, np is the number of turns of a primary winding of the transformer T1, tr is a magnetic recovery time of the transformer T1, and Tp is a working period of the switching power supply.
Further, the calculating an output power detection value Po of the switching power supply according to the output voltage detection value Vo and the output current detection value Io of the switching power supply includes:
the calculation formula of the output power detection value Po of the switching power supply is as follows:
Po=Vo×Io。
further, the output power detection value Po of the switching power supply is compared with a preset trough switching power threshold, and a comparison result is output; according to the comparison result, switching the opening point of the power switch tube Q1 from the currently locked wave trough to the corresponding target wave trough comprises the following steps:
setting a nominal power value of the switching power supply;
inquiring a corresponding trough switching power threshold in a preset power register unit according to the set nominal power value and the preset nominal power turning point percentage, and taking the corresponding trough switching power threshold as a reference power value;
and receiving the output power detection value Po of the switching power supply and the reference power value, and switching the opening point of the power switch tube Q1 from the currently locked wave trough to the corresponding target wave trough when the output power detection value Po of the switching power supply is increased or decreased to the reference power value.
The control circuit and the control method for trough latching and switching based on the output power accurately control trough switching according to the output power value detected in real time, thereby avoiding the problem of too low working frequency caused by too low FB (feedback loop) in the nominal power, optimizing the efficiency of a flyback converter, improving the power density, meeting the application design with constant power output requirement and reducing the system cost.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.
Fig. 1 is a schematic diagram of a typical flyback converter in the prior art.
Fig. 2 is a diagram of typical valley opening waveforms in the prior art.
Fig. 3 is a schematic diagram of valley-lock switching in the prior art.
Fig. 4 is a voltage-current diagram for a power output application in the prior art.
Fig. 5 is a block diagram of a structure of a control circuit for valley latching and switching based on output power according to the present invention.
Fig. 6 is a schematic diagram of an operating principle of the control circuit for valley latching and switching based on output power according to the present invention.
Fig. 7 is a schematic diagram of a valley switching power threshold table provided by the present invention.
Fig. 8 is a structural diagram of a specific embodiment of the control circuit for valley latching and switching based on output power according to the present invention.
Fig. 9 is a schematic diagram of another operation principle of the control circuit based on valley latching and switching of output power provided by the present invention.
Fig. 10 is another structural block diagram of the control circuit for valley latching and switching based on output power provided by the present invention.
Fig. 11 is a schematic diagram of a digital calculation process of the output power detection value provided by the present invention.
Fig. 12 is a schematic diagram of an operating waveform of the output power detection value calculation provided by the present invention.
Fig. 13 is a flowchart of a control method for valley latching and switching based on output power according to the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It should be understood that the data so used may be interchanged as appropriate in order to facilitate the embodiments of the invention described herein. Moreover, 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.
In this embodiment, a control circuit for locking and switching a trough based on output power is provided, and is applied to a switching power supply, as shown in fig. 5 and 8, the switching power supply includes a rectifier bridge, a transformer T1 composed of a primary winding Np, a secondary winding Ns, and an auxiliary winding Na, a power switching tube Q1, an output rectifier tube D1, a first resistor R1, a second resistor R2, a third resistor Rcs, and a controller, the controller includes a control circuit for locking and switching a trough based on output power, the control circuit for locking and switching a trough based on output power includes an output voltage detection unit, an output current detection unit, a multiplier, a preset power register unit, a comparator, and a trough switching execution unit, the input end of the output voltage detection unit is connected between a first resistor R1 and a second resistor R2 to obtain an output voltage detection signal of the switching power supply, the output end of the output voltage detection unit is connected with the first input end of the multiplier, the input end of the output current detection unit is connected between the source electrode of a power switch tube Q1 and a third resistor Rcs to obtain an output current detection signal of the switching power supply, the output end of the output current detection unit is connected with the second input end of the multiplier, the output end of the multiplier is connected with the positive input end of the comparator, the output end of the preset power register unit is connected with the negative input end of the comparator, and the output end of the comparator is connected with the trough switching execution unit;
the output voltage detection unit is used for calculating an output voltage detection value Vo of the switching power supply according to an output voltage detection signal of the switching power supply;
the output current detection unit is used for calculating an output current detection value Io of the switching power supply according to an output current detection signal of the switching power supply;
the multiplier is used for calculating an output power detection value Po of the switching power supply according to an output voltage detection value Vo and an output current detection value Io of the switching power supply;
the comparator is used for comparing an output power detection value Po of the switching power supply with a trough switching power threshold value in the preset power register unit and outputting a comparison result to the trough switching execution unit;
and the wave trough switching execution unit is used for switching the opening point of the power switch tube Q1 from the currently locked wave trough to the corresponding target wave trough according to the comparison result.
In the embodiment of the present invention, as shown in fig. 6, the constant power lines 1-5 correspond to 100% -60% of the actual output power. 100% is the actual output maximum power. And acquiring the output power detection value P0 detected in real time, wherein the trough switching execution unit can judge the trough switching execution of the next step according to the number of troughs corresponding to the current time and the change condition of the output power detection value P0. Referring to fig. 7, fig. 7 is stored in the preset power register unit, and table 1 has power thresholds corresponding to the trough switching points, for example, if the current number of troughs is 1, when the calculated output power detection value P0 is lower than 89%, the number of troughs is changed from 1 to 2. If the current valley number is 2, when the output power detection value P0 is higher than 91%, the number of locking valleys is changed from 2 to 1. And so on. Note that there is a built-in slight backlash between the power upstream and downstream.
Therefore, as can be seen from fig. 6, the control circuit based on the valley latch and switching of the output power provided by the embodiment of the present invention does not rely on the feedback voltage FB to estimate the output power any more, but can accurately control the output power according to the actual output power. Thereby avoiding the problem of too low operating frequency due to too low FB at nominal power.
Specifically, according to the operation principle of the flyback converter, the output voltage of the controller may be detected through the auxiliary winding Na, and the calculation formula of the output voltage detection value Vo of the switching power supply is as follows:
，
wherein Vout is an actual value of the output voltage of the switching power supply, na is the number of turns of the auxiliary winding of the transformer T1, and Ns is the number of turns of the secondary winding of the transformer T1.
Specifically, the calculation formula of the output current detection value Io of the switching power supply is as follows:
wherein Vcs is a peak voltage of a controller pin CS, rcs is a current sampling resistance value of the controller pin CS, np is the number of turns of a primary winding of the transformer T1, tr is a magnetic recovery time of the transformer T1, and Tp is a working period of the switching power supply.
Specifically, the calculation formula of the output power detection value Po of the switching power supply is as follows:
Po=Vo×Io。
therefore, the output power detection of the switching power supply can be completed through the existing output current detection signal CS and the output voltage detection signal ZCD, the output voltage and the output current do not need to be directly detected, and the extra cost is not added to a control circuit.
As shown in fig. 9, since the output power Po of the switching power supply is obtained according to real-time detection, under the condition that the nominal power setting is known, the controller may not perform a trough reaction on the output power Po far higher than the nominal power, for example, 100% to 180% of the nominal power segment in the embodiment, thereby avoiding uncertainty caused by adopting the FB design.
Specifically, as shown in FIG. 10, FIG. 10 shows one method of achieving nominal power settings. The switching power supply further comprises a nominal power setting unit, wherein the nominal power setting unit is used for setting a nominal power value of the switching power supply through a fuse circuit, inquiring a corresponding trough switching power threshold value in the preset power register unit according to the set nominal power value and a preset nominal power turning point percentage, and taking the corresponding trough switching power threshold value as a reference power value of the comparator;
the comparator receives the output power detection value Po of the switching power supply and the reference power value, and when the output power detection value Po of the switching power supply is increased or decreased to the reference power value, the trough switching execution unit switches the opening point of the power switching tube Q1 from the currently locked trough to the corresponding target trough.
Thus, when the full load power is equal to the nominal power, the valley switching start point can be set to a position close to the full load power. When the full load power is not equal to the nominal power, the trough switching starting point can be set to a position far away from the full load power point, so that different application requirements can be met.
As shown in fig. 11 and 12, the controller detects rising and falling edges of the DRV signal. The rising edge of the DRV signal resets the Tp counter. The output of the Tp counter gives the value of the switching period in real time. The falling edge of the DRV signal triggers the Tr counter. ZCD passes a slope detector and resets and gives a real-time value of Tr at the point where the slope suddenly drops. While sampling the ZCD signal gives the detection value Vo of the output voltage. Vcs is the peak value of CS. Kc is a design constant. And in each switching period, the digital controller calculates the voltage Vo and the current Io in real time according to the formula, and then performs multiplication to obtain a real-time power value Po. The control of the number of troughs per cycle can be achieved based on Po and the stored fixed nominal power. The present embodiment employs numerical calculation. The digital method can realize accurate detection and error-controllable multiplication and division calculation, and is therefore a suitable application method. But in principle it can also be realized in an analog manner.
As another embodiment of the present invention, as shown in fig. 13, there is provided a control method for output power based trough latching and switching, which is applied to a switching power supply, the switching power supply includes a rectifier bridge, a transformer T1 composed of a primary winding Np, a secondary winding Ns and an auxiliary winding Na, a power switching tube Q1, an output rectifier tube D1, a first resistor R1, a second resistor R2, a third resistor Rcs and a controller, and the control method for output power based trough latching and switching includes:
step S1: acquiring an output voltage detection signal and an output current detection signal of the switching power supply;
step S2: calculating to obtain an output voltage detection value Vo of the switching power supply according to the output voltage detection signal of the switching power supply, and calculating to obtain an output current detection value Io of the switching power supply according to the output current detection signal of the switching power supply;
and step S3: calculating to obtain an output power detection value Po of the switching power supply according to an output voltage detection value Vo and an output current detection value Io of the switching power supply;
and step S4: comparing the output power detection value Po of the switching power supply with a preset trough switching power threshold value, and outputting a comparison result;
step S5: and switching the opening point of the power switch tube Q1 from the currently locked wave trough to the corresponding target wave trough according to the comparison result.
Specifically, the calculating the output voltage detection value Vo of the switching power supply according to the output voltage detection signal of the switching power supply includes:
the calculation formula of the output voltage detection value Vo of the switching power supply is as follows:
wherein Vout is an actual value of the output voltage of the switching power supply, na is the number of turns of the auxiliary winding of the transformer T1, and Ns is the number of turns of the secondary winding of the transformer T1.
Specifically, the calculating the output current detection value Io of the switching power supply according to the output current detection signal of the switching power supply includes:
the calculation formula of the output current detection value Io of the switching power supply is as follows:
wherein Vcs is a peak voltage of a controller pin CS, rcs is a current sampling resistance value of the controller pin CS, np is the number of turns of a primary winding of the transformer T1, tr is a magnetic recovery time of the transformer T1, and Tp is a working period of the switching power supply.
Specifically, the calculating the output power detection value Po of the switching power supply according to the output voltage detection value Vo and the output current detection value Io of the switching power supply includes:
the calculation formula of the output power detection value Po of the switching power supply is as follows:
Po=Vo×Io。
specifically, the output power detection value Po of the switching power supply is compared with a preset trough switching power threshold, and a comparison result is output; according to the comparison result, switching the opening point of the power switch tube Q1 from the currently locked wave trough to the corresponding target wave trough comprises the following steps:
setting a nominal power value of the switching power supply;
inquiring a corresponding trough switching power threshold in a preset power register unit according to the set nominal power value and the preset nominal power turning point percentage, and taking the corresponding trough switching power threshold as a reference power value;
and receiving an output power detection value Po of the switching power supply and the reference power value, and switching the on point of the power switch tube Q1 from the currently locked wave trough to the corresponding target wave trough when the output power detection value Po of the switching power supply is increased or decreased to the reference power value.
It will be understood that the above embodiments are merely exemplary embodiments taken to illustrate the principles of the present invention, which is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.
Claims (10)
1. A trough latch and switching control circuit based on output power is applied to a switching power supply, the switching power supply comprises a rectifier bridge, a transformer T1 consisting of a primary winding Np, a secondary winding Ns and an auxiliary winding Na, a power switching tube Q1, an output rectifier tube D1, a first resistor R1, a second resistor R2, a third resistor Rcs and a controller, and is characterized in that the controller comprises the trough latch and switching control circuit based on the output power, the trough latch and switching control circuit based on the output power comprises an output voltage detection unit, an output current detection unit, a multiplier, a preset power registering unit, a comparator and a trough switching execution unit, the input end of the output voltage detection unit is connected between the first resistor R1 and the second resistor R2 to obtain an output voltage detection signal of the switching power supply, the output end of the output voltage detection unit is connected with the first input end of the multiplier, the input end of the output current detection unit is connected with the source of the power switching tube Q1 and the third resistor Rcs to obtain an output voltage detection signal of the multiplier, the output end of the multiplier is connected with the output end of the comparator, and the output end of the comparator of the multiplier is connected with the output end of the preset power switching execution unit;
the output voltage detection unit is used for calculating an output voltage detection value Vo of the switching power supply according to the output voltage detection signal of the switching power supply;
the output current detection unit is used for calculating an output current detection value Io of the switching power supply according to an output current detection signal of the switching power supply;
the multiplier is used for calculating an output power detection value Po of the switching power supply according to an output voltage detection value Vo and an output current detection value Io of the switching power supply;
the comparator is used for comparing an output power detection value Po of the switching power supply with a trough switching power threshold value in the preset power register unit and outputting a comparison result to the trough switching execution unit;
and the wave trough switching execution unit is used for switching the opening point of the power switch tube Q1 from the currently locked wave trough to the corresponding target wave trough according to the comparison result.
2. A valley latch and switch control circuit based on output power of claim 1, wherein the output voltage detection value Vo of said switching power supply is calculated by the following formula:
3. The control circuit for valley latching and switching of output power according to claim 2, wherein the output current detection value Io of said switching power supply is calculated by the following formula:
4. A valley latching and switching control circuit according to claim 3, wherein the output power detection value Po of said switching power supply is calculated by the following formula:
Po=Vo×Io。
5. the output power based trough latching and switching control circuit according to claim 1, further comprising a nominal power setting unit, wherein the nominal power setting unit is configured to set a nominal power value of the switching power supply, query a corresponding trough switching power threshold in the preset power register unit according to the set nominal power value and a preset nominal power turning point percentage, and use the corresponding trough switching power threshold as a reference power value of the comparator;
the comparator receives the output power detection value Po of the switching power supply and the reference power value, and when the output power detection value Po of the switching power supply is increased or decreased to the reference power value, the trough switching execution unit switches the opening point of the power switching tube Q1 from the currently locked trough to the corresponding target trough.
6. A trough latching and switching control method based on output power is applied to a switching power supply, the switching power supply comprises a rectifier bridge, a transformer T1 composed of a primary winding Np, a secondary winding Ns and an auxiliary winding Na, a power switch tube Q1, an output rectifier tube D1, a first resistor R1, a second resistor R2, a third resistor Rcs and a controller, and the trough latching and switching control method based on output power is characterized by comprising the following steps:
step S1: acquiring an output voltage detection signal and an output current detection signal of the switching power supply;
step S2: calculating to obtain an output voltage detection value Vo of the switching power supply according to the output voltage detection signal of the switching power supply, and calculating to obtain an output current detection value Io of the switching power supply according to the output current detection signal of the switching power supply;
and step S3: calculating to obtain an output power detection value Po of the switching power supply according to an output voltage detection value Vo and an output current detection value Io of the switching power supply;
and step S4: comparing the output power detection value Po of the switching power supply with a preset trough switching power threshold value, and outputting a comparison result;
step S5: and switching the opening point of the power switch tube Q1 from the currently locked wave trough to the corresponding target wave trough according to the comparison result.
7. The method for controlling valley latching and switching based on output power as claimed in claim 6, wherein said calculating an output voltage detection value Vo of said switching power supply according to an output voltage detection signal of said switching power supply comprises:
the calculation formula of the output voltage detection value Vo of the switching power supply is as follows:
8. The method according to claim 7, wherein said calculating an output current detection value Io of the switching power supply according to the output current detection signal of the switching power supply comprises:
the calculation formula of the output current detection value Io of the switching power supply is as follows:
9. A control method of output power based trough latching and switching according to claim 8, wherein said calculating an output power detection value Po of the switching power supply according to an output voltage detection value Vo and an output current detection value Io of the switching power supply comprises:
the calculation formula of the output power detection value Po of the switching power supply is as follows:
Po=Vo×Io。
10. the output power based trough latching and switching control method according to claim 6, wherein the output power detection value Po of the switching power supply is compared with a preset trough switching power threshold and the comparison result is output; according to the comparison result, switching the opening point of the power switch tube Q1 from the currently locked wave trough to the corresponding target wave trough comprises the following steps:
setting a nominal power value of the switching power supply;
inquiring a corresponding trough switching power threshold in a preset power register unit according to the set nominal power value and the preset nominal power turning point percentage, and taking the corresponding trough switching power threshold as a reference power value;
and receiving the output power detection value Po of the switching power supply and the reference power value, and switching the opening point of the power switch tube Q1 from the currently locked wave trough to the corresponding target wave trough when the output power detection value Po of the switching power supply is increased or decreased to the reference power value.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310043197.6A CN115864853A (en) | 2023-01-29 | 2023-01-29 | Trough latching and switching control circuit and control method based on output power |
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| CN202310043197.6A CN115864853A (en) | 2023-01-29 | 2023-01-29 | Trough latching and switching control circuit and control method based on output power |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116388552A (en) * | 2023-06-07 | 2023-07-04 | 梵塔半导体技术(杭州)有限公司 | Switching circuit control method, control chip and switching circuit |
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2023
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116388552A (en) * | 2023-06-07 | 2023-07-04 | 梵塔半导体技术(杭州)有限公司 | Switching circuit control method, control chip and switching circuit |
| CN116388552B (en) * | 2023-06-07 | 2023-09-19 | 梵塔半导体技术(杭州)有限公司 | Switching circuit control method, control chip and switching circuit |
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Application publication date: 20230328 |