CN209787027U - Feedforward sampling circuit capable of effectively suppressing ripple voltage and switching power supply thereof - Google Patents
Feedforward sampling circuit capable of effectively suppressing ripple voltage and switching power supply thereof Download PDFInfo
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- CN209787027U CN209787027U CN201920530287.7U CN201920530287U CN209787027U CN 209787027 U CN209787027 U CN 209787027U CN 201920530287 U CN201920530287 U CN 201920530287U CN 209787027 U CN209787027 U CN 209787027U
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Abstract
a feedforward sampling circuit capable of effectively suppressing ripple voltage and a switching power supply thereof are provided. The method mainly adopts a direct sampling mode: the resistance adds the resistance partial pressure value, and the feedforward sampling circuit includes: 1. a Vz terminal which is used for sampling the target value direct current component voltage and controlling the output voltage in a voltage stabilizing way and is formed by adding a resistor voltage dividing value (Vz), wherein a resistor R1 and a resistor R2 are connected between the positive electrode VO + of the output voltage and the grounding terminal in series, and the Vz terminal is a series connection point of a resistor R1 and a resistor R2; 2. a Vw end which is a feedforward sampling participating ripple suppression and fluctuates in a small range near a target value, is formed by connecting a capacitor C1 and a resistor R3 in series between the positive electrode VO + of an output voltage and a ground end, and is a series connection point of a capacitor C1 and a resistor R3; and the sampling mode is utilized to superpose the acquired data on the given input end of the control loop. So that the output ripple wave is reduced to below 10 percent, the structure is simple, the cost is low, and the ripple voltage can be effectively suppressed.
Description
Technical Field
the utility model relates to a switching power supply, especially relate to a feedforward sampling circuit and switching power supply that can effectively suppress ripple voltage.
Background
At present, in the design practice of the existing switching power supply, a series of links such as output sampling, AD conversion, digital processing, loop comparison, calculation result assignment, drive adjustment, output voltage change and the like are required to realize output voltage closed loop, so that the output voltage is kept at an expected value after stabilization.
However, the current switching power supply technology has the problems and disadvantages that the output ripple of the power supply is greatly influenced by the adjustable frequency range of the work, the size of the bus capacitor, the size of the output capacitor and the frequency of the input power supply, and if the method of suppressing the power frequency ripple by only depending on software filtering and adjusting the control loop gain can influence the output phase and stability of the power supply, so the inventor carries out further research.
SUMMERY OF THE UTILITY MODEL
In order to solve the problem that the power-off output ripple wave of the current technology exists is influenced by the adjustable frequency range of work, the size of the bus capacitor, the size of the output capacitor and the frequency of the input power supply are greatly influenced, if the method of suppressing the power frequency ripple wave by simply depending on the filtering of software and adjusting the gain of a control loop can bring influence to the output phase and the stability of the power supply, and the main technical problem to be solved is to provide a feedforward sampling circuit and a switch power supply thereof which have simple structure and low cost and can effectively suppress the ripple voltage.
In order to realize above-mentioned effect and superiority, the utility model provides a can effectively suppress ripple voltage's feedforward sampling circuit, this feedforward sampling circuit contains:
A Vz terminal which is used for sampling the target value direct current component voltage and controlling the output voltage in a voltage stabilizing way and is formed by adding a resistor voltage dividing value (Vz), wherein a resistor R1 and a resistor R2 are connected between the positive electrode VO + of the output voltage and the grounding terminal in series, and the Vz terminal is a series connection point of a resistor R1 and a resistor R2;
A Vw end which is a feedforward sampling participating ripple suppression and fluctuates in a small range near a target value, is formed by connecting a capacitor C1 and a resistor R3 in series between the positive electrode VO + of an output voltage and a ground end, and is a series connection point of a capacitor C1 and a resistor R3;
The feedforward sampling circuit collects data and superposes the data on a given input end of the control loop.
The switch power supply capable of effectively suppressing the ripple voltage of the feedforward sampling circuit comprises a control loop, wherein the control loop comprises an output sampling module, a digital control unit and a driving adjustment module, and the output sampling module comprises the feedforward sampling circuit capable of effectively suppressing the ripple voltage.
Among them, preferred are: the driving adjustment module is a DC/DC conversion unit.
Among them, preferred are: the digital control unit comprises an AD conversion module, a digital processing module, a loop comparison module and a calculation result assignment module.
among them, preferred are: and the digital control unit performs superposition operation on the numerical value acquired by feedforward sampling and a given value, performs logic operation on the numerical value acquired by direct-current component voltage sampling, and controls the DC/DC conversion unit to adjust the output voltage after PI regulation.
The utility model relates to a switching power supply that can effectively suppress ripple voltage lies in with prior art difference the utility model discloses still contain a feedforward sampling circuit that can effectively suppress ripple voltage, it has realized following control method:
1. voltage sampling and output voltage stabilization control using resistance plus resistance divided voltage value (Vz) as target value DC component
2. capacitor plus resistor voltage division value (Vw) as feedforward sampling of small-range fluctuation near target value participates in ripple suppression
3. The feed-forward sampling is superimposed on the control loop setpoint.
In a preferred embodiment of the above circuit, an AD conversion circuit is provided between the feedforward sampling circuit and a predetermined input terminal of the control loop.
Therefore, the utility model provides a can effectively suppress ripple voltage's feedforward sampling circuit can let the accurate actual fluctuation of knowing output voltage of digital control chip to effectively utilize AD usable range as far as possible, in addition reasonable reliable control method has finally reached that suppression output ripple is original 20% even 10% purpose. The utility model discloses borrow this and realized suppressing power module output ripple to the effect that one fifth is less even that does not handle and outstanding superiority under the condition that the cost does not have obvious change hardly.
the present invention will be further explained with reference to the accompanying drawings.
drawings
Fig. 1 is a schematic diagram of a feedforward sampling circuit capable of effectively suppressing ripple voltage according to the present invention;
fig. 2 is a schematic block diagram of a feed-forward sampling circuit capable of effectively suppressing ripple voltage and a power supply in a switching power supply thereof according to the present invention;
fig. 3 is a circuit diagram of an embodiment of a feedforward sampling circuit and a switching power supply thereof according to the present invention, which can effectively suppress ripple voltage;
FIG. 4 is a graph of actual ripple voltage measurements for a prior art 3-phase 380VAC AC input DC 220VDC DC output of a power supply that is solely feedback controlled by DC component voltage sampling;
Fig. 5 shows actual measured ripple voltage of a 3-phase 380VAC ac input dc 220VDC dc output according to an embodiment of the invention.
Detailed Description
In order to realize output voltage closed loop, a series of links such as output sampling, AD conversion, digital processing, loop comparison, calculation result assignment, drive adjustment, output voltage change and the like are required, so that the output voltage can be kept at an expected value after stabilization. In this closed-loop control process, two points are mainly concerned, one is that the sampling must be accurate, that is, the processor needs to know what the actual output voltage or current is at this time so as to compare with the set value, and the result of the comparison is the error that we need to adjust. The other point is that the digital processing process is reasonable, the difference obtained by comparing the sampling value with the given value is used as a control quantity, and the actual output voltage is controlled after PI regulation.
in the present invention, the output ripple voltage we pay attention to means the alternating current component superimposed in the direct current voltage, and in the ACDC power module using the frequency of 50Hz commercial power supply, the output voltage ripple is the low frequency ripple voltage with the frequency of 100Hz (single-phase power supply) or 300Hz (three-phase) in addition to the voltage fluctuation caused by the high frequency charging and discharging of the switching frequency, and the two are superimposed each other, and the low frequency ripple is generally larger than the high frequency ripple. The third method is to increase the adjustment speed of the loop PI, so that the adjustment of the switching frequency follows the fluctuation of the voltage of the bus capacitor, and the voltage of the output capacitor is relatively smooth. The former two methods inevitably bring increase of product volume and cost, the third method can not accelerate the adjusting speed without limit, and finally, the compromise or the stable state or the dynamic stability is necessary, and in practice, it is found that when the output voltage is about 1% of the actual fluctuation voltage of 220VDC, the 12 bit AD sampling is taken as an example, the adopted digital variation quantity of the output ripple wave can be only about 30, so that the disturbance can cause overshoot, and the small digital quantity variation can not be completely reflected to the driving circuit due to the PWM output precision of the digital control chip, so that the ripple wave adjusting control can be performed by using the common resistor voltage division sampling, and the ideal effect can not be achieved even if the calculating speed is faster and the calculating method is complex.
Based on the above considerations and experimental results, it is necessary to find a way for the digital control chip to accurately know the actual fluctuation of the output voltage, and to effectively utilize the available range of AD as much as possible, and to add a reasonable and reliable control method, so as to finally achieve the purpose of suppressing the output ripple to 20% or even 10%.
In order to achieve the above object, the utility model discloses mainly adopt following technical thought to go on:
1. Taking a resistance-plus-resistance voltage division value (Vz) as a target value direct current component voltage sample for output voltage stabilization control;
2. Taking a capacitance and resistance voltage division value (Vw) as a feedforward sampling of small-range fluctuation near a target value to participate in ripple suppression;
3. The feed-forward samples are superimposed on the control loop setpoint.
As shown in fig. 1, for the utility model relates to a feedforward sampling circuit schematic diagram that can effectively suppress ripple voltage, the utility model discloses a feedforward sampling circuit that can effectively suppress ripple voltage includes:
1. a Vz terminal which is used for sampling the target value direct current component voltage and controlling the output voltage in a voltage stabilizing way and is formed by adding a resistor voltage dividing value (Vz), wherein a resistor R1 and a resistor R2 are connected between the positive electrode VO + of the output voltage and the grounding terminal in series, and the Vz terminal is a series connection point of a resistor R1 and a resistor R2;
2. A Vw end which is a feedforward sampling participating ripple suppression and fluctuates in a small range near a target value, is formed by connecting a capacitor C1 and a resistor R3 in series between the positive electrode VO + of an output voltage and a ground end, and is a series connection point of a capacitor C1 and a resistor R3;
The feedforward sampling circuit collects data and superposes the data on a given input end of the control loop.
The utility model discloses a direct sampling mode: resistance adds resistance partial pressure value, the utility model discloses use the advantage of this kind of mode to lie in, the digital quantity that detects under the stable condition only fluctuates near the target value, and fundamental wave dynamic range is only tens, can regard as unchangeable after filtering again almost, so we remove processing with it as direct current signal, and the direct current volume as output voltage is used for the feedback.
meanwhile, in order to achieve the purpose of suppressing the ripple wave, the ripple wave signal needs to utilize the sampling precision of the digital chip itself in the whole range, such as the Vw point in fig. 1, when the output voltage is perfectly smooth, the potential of the Vw point is 0, in addition, because the voltage at two ends of the capacitor can not change suddenly, when the output voltage is suddenly higher than the target value at a certain moment, the potential of the Vw point will change the same with the output voltage, certainly, because of the relationship between the capacitance and the fluctuation frequency, the variation of VO + and Vw is not necessarily equal, but the time axis must coincide, and it provides the premise for controlling the ripple wave in real time after proper pull-up is performed.
In a closed-loop system, a sampling value of a target value direct-current component voltage after hardware filtering and digital filtering is approximately unchanged, an error compared with a given value is output after PI output adjustment and is used as a basis for adjusting the switching-on time of a switching tube, and the given value is a fixed value at the moment. When this is used as a means for controlling the output voltage, the result is that the output voltage ripple is large.
the technical scheme of the utility model, in order not to increase cost and volume, we utilize undulant sampling, increased resistance and used the direct sampling mode of resistance partial pressure value as feedforward sampling circuit, Vw has become a set of time-varying and output voltage wave real-time relevant digital quantity after certain transformation ratio, then do negative correlation to this value and given value, that is to say when output voltage is higher than the target control value appropriate set-down a bit the given value, when output voltage is less than the target control value appropriate set-up a bit the given value, after the PI parameter that is fit for demand condition is confirmed in the experiment, see output voltage again that output voltage has been very level and smooth. The specific control method is shown in fig. 2 and 3. As shown in fig. 2, a schematic block diagram of a feed-forward sampling circuit capable of effectively suppressing ripple voltage and a power supply in a switching power supply thereof according to the present invention is shown; fig. 3 is a circuit diagram of the feedforward sampling circuit and the switching power supply thereof according to the embodiment of the present invention, which can effectively suppress the ripple voltage;
Fig. 3 is a schematic block diagram of the switching power supply of the present invention; the figure shows that the power supply mainly comprises an input end (which can comprise input protection, input EMI (electro-magnetic interference), rectification filtering and the like), a DC/DC conversion end, an output end and a control loop (closed-loop control) mainly composed of a sampling unit and a digital control unit, wherein the digital control unit is arranged in the closed-loop control, performs superposition operation on a numerical value acquired by feedforward sampling and a given value, performs logic operation on the numerical value acquired by direct-current component voltage sampling, and controls the DC/DC conversion unit to adjust output voltage after PI (proportional integral) adjustment.
The sampling unit mainly comprises direct current component voltage sampling and feedforward sampling, converts a voltage signal acquired by the sampling unit into a digital quantity, changes Vw after a certain transformation ratio into a group of digital quantities which change along with time and are related to an output voltage wave in real time (the step can be completed by AD conversion between sampling and control), and then adds the value and a given value to be used for a control loop.
the input and output filter circuit of the switching power supply processed by the method can effectively suppress ripples within a target range by using smaller capacity and inductance, the cost and the volume are hardly increased, the input and output filter circuit can be applied within a wider range by using the same PI, and both the dynamic state and the steady state can meet standard requirements.
Through actual test, only participate in feedback control's power and existing direct current component voltage sampling and have feedforward sampling to participate in feedback control by direct current component voltage sampling the utility model discloses a power is compared, and other still very big of its output ripple voltage. The test was performed using a TDS 1002C-SC digital oscilloscope, see fig. 4, for an actual measurement of ripple voltage of a conventional 3-phase 380VAC ac input dc 220VDC dc output of a power supply that only samples dc component voltage for feedback control, the input voltage of the power supply being 380VAC, the output voltage being 220VDC10A, the ripple being shown. An oscilloscope displays 200 mV/grid, and actually measures ripple voltage 1.03V; and FIG. 5 is a graph showing the actual ripple voltage of the 3-phase 380VAC AC input DC 220VDC DC output, with the input voltage being 380VAC and the output voltage being 220VDC10A, according to one embodiment of the present invention. The oscilloscope displays 50 mV/grid, and the ripple voltage is actually measured to be 22 mV. Therefore, it is obvious from the comparison between fig. 4 and fig. 5 that the difference of the actual measured ripple voltage of the 3-phase 380VAC ac input dc 220VDC dc output proves that the ripple can be reduced to less than 10% by using the sampling and control method of the present invention.
The above-mentioned embodiments are only for describing the preferred embodiments of the present invention, and are not intended to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art without departing from the design spirit of the present invention should fall into the protection scope defined by the claims of the present invention.
Claims (7)
1. the utility model provides a switching power supply of ripple voltage can effectively be suppressed, contains control loop, control loop includes output sampling module, digital control unit and drive adjustment module, its characterized in that:
The output sampling module contains the feedforward sampling circuit that can effectively suppress ripple voltage, the feedforward sampling circuit contains:
A Vz terminal which is used for sampling the target value direct current component voltage and controlling the output voltage in a voltage stabilizing way and is formed by adding a resistor voltage dividing value (Vz), wherein a resistor R1 and a resistor R2 are connected between the positive electrode VO + of the output voltage and the grounding terminal in series, and the Vz terminal is a series connection point of a resistor R1 and a resistor R2;
A Vw end which is a feedforward sampling participating ripple suppression and fluctuates in a small range near a target value, is formed by connecting a capacitor C1 and a resistor R3 in series between the positive electrode VO + of an output voltage and a ground end, and is a series connection point of a capacitor C1 and a resistor R3;
the feedforward sampling circuit collects data and superposes the data on a given input end of the control loop.
2. The switching power supply according to claim 1, wherein: the driving adjustment module is a DC/DC conversion unit.
3. The switching power supply according to claim 2, wherein: the digital control unit comprises an AD conversion module, a digital processing module, a loop comparison module and a calculation result assignment module.
4. A switching power supply capable of effectively suppressing ripple voltage according to claim 3, wherein: and the digital control unit performs superposition operation on the numerical value acquired by feedforward sampling and a given value, performs logic operation on the numerical value acquired by direct-current component voltage sampling, and controls the DC/DC conversion unit to adjust the output voltage after PI regulation.
5. the switching power supply according to claim 4, wherein: the digital control unit converts the signals collected by the feedforward sampling into numerical values of digital quantities related to the output voltage waves in real time through AD conversion.
6. a feed-forward sampling circuit capable of effectively suppressing ripple voltage, applied to the switching power supply of any one of the preceding claims, wherein: the feed-forward sampling circuit comprises:
A Vz terminal which is used for sampling the target value direct current component voltage and controlling the output voltage in a voltage stabilizing way and is formed by adding a resistor voltage dividing value (Vz), wherein a resistor R1 and a resistor R2 are connected between the positive electrode VO + of the output voltage and the grounding terminal in series, and the Vz terminal is a series connection point of a resistor R1 and a resistor R2;
A Vw end which is a feedforward sampling participating ripple suppression and fluctuates in a small range near a target value, is formed by connecting a capacitor C1 and a resistor R3 in series between the positive electrode VO + of an output voltage and a ground end, and is a series connection point of a capacitor C1 and a resistor R3;
the feedforward sampling circuit collects data and superposes the data on a given input end of the control loop.
7. A feed-forward sampling circuit capable of effectively suppressing ripple voltage according to claim 6, wherein: an AD conversion is arranged between the feedforward sampling circuit and a given input end of the control loop.
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| CN201920530287.7U CN209787027U (en) | 2019-04-18 | 2019-04-18 | Feedforward sampling circuit capable of effectively suppressing ripple voltage and switching power supply thereof |
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| CN201920530287.7U CN209787027U (en) | 2019-04-18 | 2019-04-18 | Feedforward sampling circuit capable of effectively suppressing ripple voltage and switching power supply thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2022001938A1 (en) * | 2020-06-28 | 2022-01-06 | 中兴通讯股份有限公司 | Ripple detection apparatus and ripple suppression apparatus |
| CN114430227A (en) * | 2022-02-07 | 2022-05-03 | Oppo广东移动通信有限公司 | Ripple voltage processing device and method and switching power supply |
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2019
- 2019-04-18 CN CN201920530287.7U patent/CN209787027U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2022001938A1 (en) * | 2020-06-28 | 2022-01-06 | 中兴通讯股份有限公司 | Ripple detection apparatus and ripple suppression apparatus |
| CN114430227A (en) * | 2022-02-07 | 2022-05-03 | Oppo广东移动通信有限公司 | Ripple voltage processing device and method and switching power supply |
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Effective date of registration: 20211122 Address after: 710061 in the yard of plant a on the north side of No. 117, West Avenue, Xiliu Street office, high tech Zone, Xi'an, Shaanxi Province Patentee after: Xi'an Huowei Power Supply Co.,Ltd. Address before: 050000 no.350 Lijiang Road, high tech Zone, Shijiazhuang, Hebei Province Patentee before: SHIJIAZHUANG TONGHE ELECTRONICS Co.,Ltd. |