CN115833630A - Valley filling circuit and control method thereof - Google Patents
Valley filling circuit and control method thereof Download PDFInfo
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Abstract
The invention relates to a valley filling circuit and a control method thereof, wherein the valley filling circuit comprises a control circuit, a first power tube and a first capacitor; the first power tube is connected in series with the first capacitor and then connected between the high potential input end and the low potential input end of the valley filling circuit, and is also connected between the high potential output end and the low potential output end of the valley filling circuit; the control circuit controls the working state of the first power tube so that the voltage of the first capacitor is stabilized within the error range of the preset voltage; when the voltage of the first capacitor is smaller than the preset voltage, the control circuit controls the first power tube to be completely conducted. According to the valley filling circuit and the control method thereof, under the condition of high-voltage input, the valley filling function is realized, and PF and THD are optimized; under the low-voltage input, the first power tube is completely conducted, and the working state of the valley filling circuit is completely the same as that of the traditional rectification scheme. Compared with the traditional rectification scheme, the voltage resistance of the first capacitor in the invention can be selected to be lower, and the volume of the system is greatly reduced.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a valley filling circuit and a control method thereof.
Background
At present, an AC/DC converter is connected to a power grid through a rectifying circuit, and an input portion of the AC/DC converter is generally composed of a bridge rectifier and a filter capacitor, as shown in fig. 1, both of which belong to nonlinear components. Due to the existence of the large-capacity filter capacitor, the conduction angle of the rectifier diode becomes narrow, and the rectifier diode can be conducted only near the peak value of the alternating current input voltage, so that the alternating current input current generates serious distortion and becomes a peak pulse.
In order to solve the above problems, in the prior art, a valley filling circuit is usually added at the rear end of the bridge rectifier circuit, and the valley filling circuit can spread the current waveform after rectification and filtration of the ac mains from a narrow pulse shape to a shape close to a sine wave shape, which is equivalent to a circuit that "fills in" a large part of the valley point region in the narrow pulse current waveform.
The conventional valley-fill circuit is shown in fig. 2, and requires three additional diodes in addition to two capacitors, which increases the cost. And when the valley filling work is carried out, the three diodes generate larger conduction loss, and the efficiency is lower. For example, the minimum voltage of the valley-fill circuit output voltage Vo of fig. 2 is the peak voltage V AC 1/2, therefore, when the low-voltage input is carried out, the fluctuation of Vo is large, the minimum voltage of Vo is low, and therefore the input voltage range of the rear-stage load is wide and the efficiency is low.
Disclosure of Invention
The embodiment of the invention provides a valley filling circuit and a control method thereof, which at least solve the problems of high hardware cost and low working efficiency of the valley filling circuit in the prior art.
In a first aspect, an embodiment of the present invention provides a valley filling circuit, which receives a rectified voltage to provide an input voltage of a subsequent circuit, and is characterized by including a control circuit, a first power transistor, and a first capacitor; wherein,
the first power tube is connected in series with the first capacitor and then connected between a high potential input end and a low potential input end of the valley filling circuit, and the first power tube is connected in series with the first capacitor and then connected between a high potential output end and a low potential output end of the valley filling circuit;
the control circuit controls the working state of the first power tube so that the voltage of the first capacitor is stabilized within an error range of a preset voltage;
when the voltage of the first capacitor is smaller than the preset voltage, the control circuit controls the first power tube to be completely conducted.
Further, when the voltage provided to the first capacitor is greater than the preset voltage, the control circuit controls the working state of the first power tube so that the voltage of the first capacitor is stabilized at the preset voltage.
Further, when the voltage provided to the first capacitor is greater than the preset voltage, the control circuit controls the first power tube to work in a linear region.
Further, the valley filling circuit further comprises a first inductor and a second power tube, and the first inductor and the first power tube and the first capacitor form a switching power supply, wherein the voltage of the first capacitor is used as the output voltage of the switching power supply,
when the voltage provided to the first capacitor is larger than the preset voltage, the control circuit controls the first power tube to work in a switch mode.
In some preferred embodiments, the control circuit includes a voltage detection terminal and a driving terminal; the voltage detection end of the control circuit is connected with the first capacitor to obtain a capacitor voltage sampling signal; the driving end of the control circuit is connected with the control end of the first power tube; the control circuit controls the working state of the first power tube according to the capacitance voltage sampling signal.
In some preferred embodiments, a reference voltage is provided in the control circuit, the control circuit performs error amplification on the capacitance voltage sampling signal and the reference voltage, a driving signal is generated according to an error amplification result, and the driving end of the control circuit outputs the driving signal.
Further, a first end of the first capacitor is connected with a high-potential input end of the valley filling circuit, a second end of the first capacitor is connected with a first power end of the first power tube, a second power end of the first power tube is connected with a low-potential input end of the valley filling circuit, and the first end of the first capacitor and the second power end of the first power tube are respectively used as a high-potential output end and a low-potential output end of the valley filling circuit;
the voltage detection end of the control circuit comprises a first voltage detection end and a second voltage detection end which are respectively connected with the first end and the second end of the first capacitor.
Further, a first power end of the first power tube is connected with a high-potential input end of the valley filling circuit, a second power end of the first power tube is connected with a first end of the first capacitor, a second end of the first capacitor is connected with a low-potential input end of the valley filling circuit, and the first power end of the first power tube and the second end of the first capacitor are respectively used as a high-potential output end and a low-potential output end of the valley filling circuit;
and the voltage detection end of the control circuit is connected with the first end of the first capacitor.
In some preferred embodiments, one end of the first inductor is connected to one of a high potential input terminal and a low potential input terminal of the valley-fill circuit, wherein,
when one end of the first inductor is connected with the high-potential input end of the valley filling circuit, the other end of the first inductor is connected with the high-potential output end of the valley filling circuit;
when one end of the first inductor is connected with the low potential input end of the valley filling circuit, the other end of the first inductor is connected with the low potential output end of the valley filling circuit.
In a second aspect, the present invention provides a method for controlling a valley-fill circuit according to any one of the above embodiments,
controlling the working state of the first power tube to enable the voltage of the first capacitor to be stabilized within an error range of preset voltage;
and when the voltage of the first capacitor is smaller than the preset voltage, controlling the first power tube to be completely conducted.
Further, when the voltage provided to the first capacitor is greater than the preset voltage, the operating state of the first power tube is controlled so that the voltage of the first capacitor is stabilized at the preset voltage.
Further, when the voltage provided to the first capacitor is greater than the preset voltage, the first power tube is controlled to operate in a linear region or a switch mode.
In some preferred embodiments, the controlling the operating state of the first power transistor includes:
obtaining a capacitor voltage sampling signal according to the voltage at two ends of the first capacitor;
carrying out error amplification on the capacitor voltage sampling signal and the reference voltage, and generating a driving signal according to an error amplification result;
and controlling the working state of the first power tube according to the driving signal.
Compared with the related art, the valley filling circuit and the control method thereof provided by the embodiment of the invention control the voltage at two ends of the first capacitor within the error range of the preset voltage, and particularly control the first power tube to be completely conducted by the control circuit when the voltage of the first capacitor is smaller than the preset voltage. By the valley filling circuit, when the AC rectified output voltage is greater than the preset voltage, the voltage of the first capacitor is equal to the preset voltage, and the later-stage DC-DC circuit supplies current by the AC input voltage, so that the conduction angle of the input current is increased, and the THD (total harmonic distortion) and the PF (power factor) are optimized; when the AC rectification output voltage is smaller than the preset voltage, the first power tube is completely conducted, the first capacitor supplies current to the rear-stage load, and the first capacitor discharges, so that the valley filling circuit function under the high-voltage input is realized. Therefore, under the condition of high-voltage input, the valley filling circuit of the embodiment of the invention realizes the valley filling function, and optimizes the PF and the THD; under the low-voltage input, the first power tube is completely conducted, and the working state of the valley filling circuit is completely the same as that of the traditional rectification scheme. Compared with the traditional rectification scheme, the first capacitor has lower withstand voltage for the same capacitor capacity, and the volume of the system is greatly reduced.
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 invention and do not limit the invention. In the drawings:
FIG. 1 is a circuit schematic of a rectifier circuit of a conventional rectification scheme;
FIG. 2 is a schematic circuit diagram of a prior art valley fill circuit;
FIG. 3 is a schematic circuit diagram of a valley filling circuit according to an embodiment of the present invention;
FIG. 4 is a waveform diagram of the output voltage of the valley filling circuit of the embodiment of FIG. 3;
FIG. 5 is a schematic circuit diagram of a valley filling circuit according to another embodiment of the present invention;
FIG. 6 is a schematic circuit diagram of a valley filling circuit according to another embodiment of the present invention;
fig. 7 is a schematic circuit diagram of a valley fill circuit according to another embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments provided by the present invention, belong to the protection scope of the present invention. Moreover, it should be further appreciated that such a development effort might be complex and tedious, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, and thus should not be construed as a limitation of the present disclosure.
Reference in the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one of ordinary skill in the art that the described embodiments of the present invention can be combined with other embodiments without conflict.
Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention are not to be construed as limiting in number, and may be construed to cover both the singular and the plural. The present invention relates to the terms "comprises," "comprising," "includes," "including," "has," "having" and any variations thereof, which are intended to cover non-exclusive inclusions; for example, a process, method, system, article, or apparatus that comprises a list of steps or modules (elements) is not limited to the listed steps or elements, but may include additional steps or elements not listed, or may include additional steps or elements inherent to such process, method, article, or apparatus. The terms "connected," "coupled," and the like in the description of the invention are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The term "plurality" as used herein means greater than or equal to two. "and/or" describing the association relationship of the associated objects, indicates that three relationships may exist, for example, "a and/or B" may indicate: a exists alone, A and B exist simultaneously, and B exists alone. The terms "first," "second," "third," and the like as referred to herein, merely distinguish between similar objects and do not denote a particular ordering of the objects.
The valley filling circuit provided by the invention is connected between the output end of the rectifying circuit and the input end of the post-stage DC-DC circuit, receives the rectified voltage to provide the input voltage of the post-stage circuit, and the basic implementation scheme is as follows: the power supply comprises a control circuit, a first power tube and a first capacitor. The first power tube is connected in series with the first capacitor and then connected between a high potential input end and a low potential input end of the valley filling circuit, and the first power tube is connected in series with the first capacitor and then connected between a high potential output end and a low potential output end of the valley filling circuit. In the embodiment of the invention, the working state of the first power tube is controlled by the control circuit, so that the voltage of the first capacitor is stabilized within the error range of the preset voltage.
The invention controls the capacitor voltage within the error range of the preset voltage, when the rectification voltage output by the rectification circuit is higher, the voltage provided for the first capacitor is large enough, thereby controlling the capacitor voltage to be stabilized at the preset voltage; and when the rectified voltage output by the rectifying circuit is lower, the voltage provided for the first capacitor is smaller than the preset voltage, and the voltage of the capacitor is smaller than the preset voltage. Therefore, when the capacitor voltage is lower than the preset voltage, it can be reflected that the rectified voltage output by the rectifying circuit is too low at this time, and the control circuit is required to control the first power tube to be completely conducted, so that the first capacitor supplies power to the subsequent circuit at the same time. When the voltage supplied to the first capacitor is greater than the preset voltage, the control circuit controls the working state of the first power tube to enable the voltage of the first capacitor to be stabilized at the preset voltage, specifically, when the voltage supplied to the first capacitor is greater than the preset voltage, the control circuit controls the first power tube to work in a linear region, the first power tube is not completely conducted, and the first capacitor does not supply power to a rear-stage circuit any more. Namely, the valley filling circuit can effectively increase the conduction angle under the condition of selecting proper preset voltage.
In some preferred embodiments, the control circuit includes a voltage detection terminal and a driving terminal; a first power tube is connected between a positive output end and a negative output end of a rectification circuit after being connected with the first capacitor in series, and a voltage detection end of the control circuit is connected with the first capacitor to obtain a capacitor voltage sampling signal; the driving end of the control circuit is connected with the control end of the first power tube; the control circuit controls the working state of the first power tube according to the capacitance voltage sampling signal.
The control circuit is internally provided with a reference voltage, the control circuit carries out error amplification on the capacitance voltage sampling signal and the reference voltage, a driving signal is generated according to an error amplification result, and a driving end of the control circuit outputs the driving signal.
In a preferred embodiment of the present invention, the valley fill circuit further includes a first inductor and a second power transistor, and the first inductor, the second power transistor and the first capacitor form a switching power supply. Similarly, when the voltage of the first capacitor is smaller than the preset voltage, the control circuit controls the first power tube to be completely conducted; when the voltage supplied to the first capacitor is larger than the preset voltage, the control circuit controls the first power tube to work in a switching mode.
Based on the basic implementation scheme, the four embodiments are adopted for detailed description. Fig. 3 and fig. 5 to fig. 7 respectively illustrate circuit structures of first to fourth embodiments, all based on the same inventive concept, but the specific circuit implementation is different, and the first switch tube of the embodiments of the present invention employs an N-type MOS tube to match with corresponding application, where a drain of the N-type MOS tube is used as a first power end, a source is used as a second power end, and a gate is used as a control end. For the valley filling circuit using P-type MOS transistors, the connection relationship of the circuit can be changed according to the characteristics of the P-type MOS transistors, and the present invention is not described in detail herein.
In an embodiment of the present invention, a first end of the first capacitor is connected to a high-potential input end of the valley fill circuit, a second end of the first capacitor is connected to a first power end of the first power transistor, a second power end of the first power transistor is connected to a low-potential input end of the valley fill circuit, and the first end of the first capacitor and the second power end of the first power transistor are respectively used as a high-potential output end and a low-potential output end of the valley fill circuit; the voltage detection end of the control circuit comprises a first voltage detection end and a second voltage detection end which are respectively connected with the first end and the second end of the first capacitor.
More specifically, as shown in fig. 3, in this embodiment, an electrolytic capacitor C1 is used as a first capacitor, a first end and a second end of the first capacitor are respectively an anode and a cathode of the electrolytic capacitor C1, a first voltage detection end of the control circuit U1 and the anode of the electrolytic capacitor C1 are both connected to a positive output end of the rectifier circuit, the cathode of the electrolytic capacitor C1 is coupled to a drain of the first power tube Q1 and a second voltage detection end of the control circuit U1, a source of the first power tube Q1 and a first port of the control circuit U1 are both connected to a negative output end of the rectifier circuit, and a gate of the first power tube Q1 is connected to a driving end of the control circuit U1 as a control end; and the anode of the electrolytic capacitor C1 and the source electrode of the first power tube Q1 are respectively used as a high-potential output end and a low-potential output end of the valley filling circuit. In this embodiment, the low potential input terminal and the low potential output terminal of the valley fill circuit are grounded, and the control circuit U1 further includes a third port, which is grounded.
As shown in fig. 3, the valley filling circuit is connected between a rectifying circuit and a subsequent circuit, such as a DC-DC circuit, the rectifying circuit of the present embodiment is a bridge circuit composed of four diodes, the rectifying circuit rectifies an incoming alternating Input voltage (AC Input) to output a rectified voltage, and the valley filling circuit receives the rectified voltage to obtain an AC rectified output voltage V _ dclink as an Input voltage of the subsequent DC-DC circuit. The control circuit of this embodiment may adopt a control chip, and the valley filling circuit controls the first power transistor Q1 through the control circuit U1 to stabilize the voltage Vc across the first capacitor (i.e., the capacitor voltage) within the error range of the preset voltage Vreg. Specifically, the reference voltage is preset in the control circuit, the control circuit U1 compares a capacitor voltage sampling signal representing the capacitor voltage Vc with the reference voltage, the control circuit U1 performs error amplification according to the comparison result, a driving signal is generated according to the amplified result, the driving signal is output by a driving end of the control circuit, and the working state of the first power tube Q1 is controlled according to the driving signal, so that the voltage at two ends of the electrolytic capacitor C1 is stabilized at the preset voltage Vreg.
Referring to fig. 4, in a section from t1 to t2, V _ dclink > Vreg, a first power tube Q1 works in a linear region or an approximate cut-off region, at this time, an electrolytic capacitor C1 does not supply power to a subsequent stage DC-DC circuit, and only a leakage current of the electrolytic capacitor C1 is consumed, so that the first power tube Q1 is in an approximate cut-off state at this time; in the interval from t2 to t3, V _ dclink < Vreg, the electrolytic capacitor C1 supplies power to the rear-stage DC-DC circuit, the first power tube Q1 is completely conducted, and the capacitor voltage Vc is approximately equal to V _ dclink. As shown in the waveform of fig. 4, the conduction angle of the input current is greatly increased relative to that of the conventional rectification scheme shown in fig. 1, so that the effects of optimizing THD (total harmonic distortion) and PF (power factor) are achieved. On the other hand, the valley filling circuit can be compatible with the traditional rectification scheme under the low-voltage input. Because the voltage Vc of the capacitor is controlled within the error range of the preset voltage, the electrolytic capacitor C1 can select the first capacitor with low withstand voltage, thereby achieving the effect of greatly reducing the volume of the first capacitor.
According to the invention, the voltage at two ends of the first capacitor is controlled within the error range of the preset voltage, so that when the AC rectified output voltage V _ dclink is greater than the preset voltage Vreg, the capacitor voltage Vc = Vreg (the tiny error can be ignored), and at the moment, the later-stage DC-DC circuit provides current from an AC input (alternating current input voltage), the conduction angle of the input current is increased, and THD and PF are optimized; when the AC rectified output voltage V _ dclink is less than Vreg, the first power tube Q1 works in a saturation area and is completely conducted, the electrolytic capacitor C1 provides current for a rear-stage load, and the electrolytic capacitor C1 discharges, so that the valley filling circuit function under high-voltage input is realized.
In summary, under high-voltage input, the valley filling circuit of the embodiment of the invention realizes the valley filling function, optimizes the PF and the THD; at low voltage input, the first power transistor Q1 is fully conductive, and the valley-fill circuit operates as a conventional rectification scheme as shown in fig. 1, but with the same capacitance capacity, the invention can stabilize the voltage at two ends of the first capacitor voltage within the error range of the preset voltage, so the withstand voltage of the electrolytic capacitor C1 in the invention can be lower, and the volume of the system is greatly reduced.
In another embodiment of the present invention, the connection relationship between the control circuit, the first power transistor and the first capacitor may be adjusted, for example, the first power transistor is placed on the high potential side. Specifically, a first power end of the first power tube is connected to a high potential input end of the valley filling circuit, a second power end of the first power tube is connected to a first end of the first capacitor, a second end of the first capacitor is connected to a low potential input end of the valley filling circuit, and the first power end of the first power tube and the second end of the first capacitor are respectively used as a high potential output end and a low potential output end of the valley filling circuit; and the voltage detection end of the control circuit is connected with the first end of the first capacitor.
Specifically, referring to fig. 5, a drain of the first power tube Q1 is connected to a positive output end of the rectifier circuit, a voltage detection end of the control circuit U1 and an anode of the electrolytic capacitor C1 are both coupled to a source of the first power tube Q1, a cathode of the electrolytic capacitor C1 and a first port of the control circuit U1 are both connected to a negative output end of the rectifier circuit, and a gate of the first power tube Q1 is connected to a driving end of the control circuit U1 as a control end; and the drain electrode of the first power tube Q1 and the cathode of the electrolytic capacitor C1 are respectively used as a positive output end and a negative output end of the valley filling circuit. In this embodiment, the low potential input terminal and the low potential output terminal of the valley fill circuit are grounded, and the control circuit U1 further includes a second port, which is grounded. It should be noted that, for specific examples in this embodiment, reference may be made to examples described in the foregoing embodiments and optional implementations, and details of this embodiment are not described herein again.
In other embodiments of the present invention, the present invention is not limited to the linear power supply structure mentioned in the above embodiments, and may be any DC-DC power supply, such as a BUCK-type switching power supply like BUCK. For the DC-DC power supply circuit, the valley filling circuit also comprises a first inductor and a second power tube, and the first inductor, the second power tube and the first capacitor form a switching power supply. Specifically, one end of the first inductor of the present invention is connected to one of the high potential input terminal and the low potential input terminal of the valley fill circuit. When one end of the first inductor is connected with the high-potential input end of the valley filling circuit, the other end of the first inductor is connected with the high-potential output end of the valley filling circuit; when one end of the first inductor is connected with the low potential input end of the valley filling circuit, the other end of the first inductor is connected with the low potential output end of the valley filling circuit.
In an embodiment of the present invention, the second power transistor of the present invention employs a diode, and referring to fig. 6, a specific connection relationship between the diode and the first inductor, the valley filling circuit of the present embodiment is formed by adding the diode and the inductor on the basis of fig. 3. The anode of the diode D1 is coupled to the drain of the first power tube Q1 and the cathode of the electrolytic capacitor C1, and the cathode of the diode D1 is connected to the forward output end of the rectifier circuit; the first end of the first inductor L is connected with the positive output end of the rectifying circuit, and the second end of the first inductor L is connected with the positive electrode of the electrolytic capacitor C1. In this embodiment, the first inductor L, the diode D1, the first power tube Q1 and the electrolytic capacitor C1 constitute a switching power supply, wherein the voltage across the first capacitor C1 is used as the output voltage of the switching power supply, and when the voltage supplied to the first capacitor C1 is greater than the preset voltage, the control circuit U1 controls the first power tube Q1 to operate in the switching mode; when the voltage supplied to the first capacitor C1 is smaller than the preset voltage, the control circuit U1 controls the first power tube Q1 to operate in the saturation region, and the first power tube Q1 is turned on.
Referring to fig. 7, in another embodiment of the present invention, an anode of the diode D1 is coupled to the negative output terminal of the rectifying circuit and the first terminal of the first inductor L, a cathode of the diode D1 is coupled to the source of the first power transistor Q1 and the anode of the electrolytic capacitor C1, and a second terminal of the first inductor L is connected to the cathode of the electrolytic capacitor C1. In this embodiment, the control circuit U1 only has a driving end and a voltage detection end, the driving end is connected to the control end of the first power tube Q1, and the voltage detection end is connected to the anode of the electrolytic capacitor C1. In this embodiment, the first inductor L, the diode D1, the first power tube Q1 and the electrolytic capacitor C1 constitute a switching power supply, and similarly, the voltage at two ends of the first capacitor C1 is used as the output voltage of the switching power supply, and when the voltage supplied to the first capacitor C1 is greater than the preset voltage, the control circuit U1 controls the first power tube Q1 to operate in the switching mode; when the voltage supplied to the first capacitor C1 is smaller than the preset voltage, the control circuit U1 controls the first power tube Q1 to operate in the saturation region, and the first power tube Q1 is turned on.
In other embodiments of the present invention, an inductor may also be connected in series between the first capacitor and the first switching tube, and for specific examples in this embodiment, reference may be made to the examples described in the above embodiments and optional embodiments, which are not described herein again.
Based on the valley filling circuit, the invention provides a control method, which controls the working state of the first power tube to stabilize the voltage of the first capacitor within the error range of the preset voltage, wherein when the voltage of the first capacitor is smaller than the preset voltage, the first power tube is controlled to be completely conducted; when the voltage provided to the first capacitor is larger than the preset voltage, the working state of the first power tube is controlled so that the voltage of the first capacitor is stabilized at the preset voltage.
Specifically, the control circuit of the invention obtains a capacitance voltage sampling signal of the first capacitor through a voltage detection end of the control circuit; and then controlling the working state of the first power tube according to the capacitor voltage sampling signal so as to increase the conduction angle of the rectifying circuit. The control circuit is internally provided with a reference voltage, and the control circuit performs error amplification on the capacitance voltage sampling signal and the reference voltage or performs error amplification on a comparison result of the capacitance voltage sampling signal and the reference voltage, and generates a driving signal according to an error amplification result; and controlling the working state of the first power tube according to the driving signal. When the voltage supplied to the first capacitor is greater than the preset voltage, controlling the first power tube to work in a linear region or a switching mode; when the voltage of the first capacitor is smaller than the preset voltage, the first power tube is controlled to work in a saturation region, and therefore the purpose that the voltage at two ends of the first capacitor is stabilized within an error range of the preset voltage is achieved.
According to the invention, the voltage Vc at two ends of the first capacitor is controlled at the preset voltage Vreg, when low-voltage input is carried out, if the voltage at two ends of the first capacitor is less than the preset voltage Vreg, Q1 works in a saturation region and is completely conducted, so that the effect of increasing the conduction angle is achieved.
Referring to fig. 3 and 4, the method of the present invention is explained, in the interval from t1 to t2, when the AC rectified output voltage V _ dclink > Vreg, the first power tube Q1 operates in the linear region or the approximate cut-off region, and at this time, the electrolytic capacitor C1 does not supply power to the subsequent stage circuit, and only the leakage current of the electrolytic capacitor C1 is consumed, so the first power tube Q1 is in the approximate cut-off state at this time; in the interval from t2 to t3, when the AC rectification output voltage V _ dclink is less than Vreg, the electrolytic capacitor C1 supplies power to the rear-stage circuit, the first power tube Q1 is completely conducted, and the capacitor voltage Vc is approximately equal to V _ dclink. As can be seen from the waveforms in fig. 4, the conduction angle of the input current is greatly increased compared to that of the conventional rectification scheme shown in fig. 1, so that the THD and PF are optimized. On the other hand, the valley filling circuit adopting the control method of the invention can be compatible with the traditional rectification scheme under low-voltage input, but compared with the traditional rectification scheme shown in fig. 1, the electrolytic capacitor C1 in the invention can select the low-voltage-resistant first capacitor, thereby achieving the effect of greatly reducing the volume of the first capacitor.
It should be noted that, for specific examples in this embodiment, reference may be made to examples described in the foregoing embodiments and optional implementation manners, and details of this embodiment are not described herein again.
It should be understood by those skilled in the art that various features of the above-described embodiments can be combined in any combination, and for the sake of brevity, all possible combinations of features in the above-described embodiments are not described in detail, but rather, all combinations of features which are not inconsistent with each other should be construed as being within the scope of the present disclosure.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (13)
1. A valley filling circuit receives a rectified voltage to provide an input voltage of a post-stage circuit, and is characterized by comprising a control circuit, a first power tube and a first capacitor; wherein,
the first power tube is connected in series with the first capacitor and then connected between a high potential input end and a low potential input end of the valley filling circuit, and the first power tube is connected in series with the first capacitor and then connected between a high potential output end and a low potential output end of the valley filling circuit;
the control circuit controls the working state of the first power tube so that the voltage of the first capacitor is stabilized within an error range of preset voltage;
when the voltage of the first capacitor is smaller than the preset voltage, the control circuit controls the first power tube to be completely conducted.
2. The valley-fill circuit of claim 1,
when the voltage provided to the first capacitor is greater than the preset voltage, the control circuit controls the working state of the first power tube so that the voltage of the first capacitor is stabilized at the preset voltage.
3. The valley fill circuit of claim 2, wherein the control circuit controls the first power transistor to operate in a linear region when the voltage supplied to the first capacitor is greater than the preset voltage.
4. The valley filling circuit according to claim 2, further comprising a first inductor and a second power transistor, and forming a switching power supply with the first power transistor and the first capacitor, wherein the voltage of the first capacitor is used as the output voltage of the switching power supply,
when the voltage provided to the first capacitor is larger than the preset voltage, the control circuit controls the first power tube to work in a switch mode.
5. The valley-fill circuit of claim 1,
the control circuit comprises a voltage detection end and a driving end; the voltage detection end of the control circuit is connected with the first capacitor to obtain a capacitor voltage sampling signal; the driving end of the control circuit is connected with the control end of the first power tube; the control circuit controls the working state of the first power tube according to the capacitance voltage sampling signal.
6. The valley filling circuit according to claim 5, wherein a reference voltage is provided in the control circuit, the control circuit performs error amplification on the capacitance voltage sampling signal and the reference voltage, a driving signal is generated according to an error amplification result, and a driving end of the control circuit outputs the driving signal.
7. The valley filling circuit of claim 5, wherein a first terminal of the first capacitor is connected to a high potential input terminal of the valley filling circuit, a second terminal of the first capacitor is connected to a first power terminal of the first power transistor, a second power terminal of the first power transistor is connected to a low potential input terminal of the valley filling circuit, and the first terminal of the first capacitor and the second power terminal of the first power transistor are respectively used as a high potential output terminal and a low potential output terminal of the valley filling circuit;
the voltage detection end of the control circuit comprises a first voltage detection end and a second voltage detection end which are respectively connected with the first end and the second end of the first capacitor.
8. The valley-fill circuit of claim 5,
a first power end of the first power tube is connected with a high-potential input end of the valley filling circuit, a second power end of the first power tube is connected with a first end of the first capacitor, a second end of the first capacitor is connected with a low-potential input end of the valley filling circuit, and the first power end of the first power tube and the second end of the first capacitor are respectively used as a high-potential output end and a low-potential output end of the valley filling circuit;
and the voltage detection end of the control circuit is connected with the first end of the first capacitor.
9. The valley-fill circuit according to claim 4, wherein one terminal of the first inductor is connected to one of a high potential input terminal and a low potential input terminal of the valley-fill circuit, wherein,
when one end of the first inductor is connected with the high-potential input end of the valley filling circuit, the other end of the first inductor is connected with the high-potential output end of the valley filling circuit;
when one end of the first inductor is connected with the low potential input end of the valley filling circuit, the other end of the first inductor is connected with the low potential output end of the valley filling circuit.
10. A control method based on the valley-fill circuit of any one of claims 1 to 9,
controlling the working state of the first power tube to enable the voltage of the first capacitor to be stabilized within an error range of preset voltage;
and when the voltage of the first capacitor is smaller than the preset voltage, controlling the first power tube to be completely conducted.
11. The control method according to claim 10, wherein when the voltage supplied to the first capacitor is greater than the preset voltage, the operating state of the first power transistor is controlled so that the voltage of the first capacitor is stabilized at the preset voltage.
12. The control method according to claim 11, wherein when the voltage applied to the first capacitor is greater than the preset voltage, the first power transistor is controlled to operate in a linear region or a switching mode.
13. The control method according to claim 10, wherein the controlling the operating state of the first power transistor comprises:
obtaining a capacitor voltage sampling signal according to the voltage at two ends of the first capacitor;
carrying out error amplification on the capacitance voltage sampling signal and the reference voltage, and generating a driving signal according to an error amplification result;
and controlling the working state of the first power tube according to the driving signal.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210699568.1A CN115833630A (en) | 2022-06-20 | 2022-06-20 | Valley filling circuit and control method thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210699568.1A CN115833630A (en) | 2022-06-20 | 2022-06-20 | Valley filling circuit and control method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116545268A (en) * | 2023-05-08 | 2023-08-04 | 深圳讴艾半导体有限公司 | LC converter |
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2022
- 2022-06-20 CN CN202210699568.1A patent/CN115833630A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116545268A (en) * | 2023-05-08 | 2023-08-04 | 深圳讴艾半导体有限公司 | LC converter |
| CN116545268B (en) * | 2023-05-08 | 2024-03-12 | 深圳讴艾半导体有限公司 | LC converter |
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