TW201838300A - Converter - Google Patents

Abstract

A converter includes a switching circuit, a resonant circuit, a rectifying circuit, and a transformer including a primary winding, and a secondary winding. The switching circuit is configured to convert a DC input voltage to a switching signal. The resonant circuit is electrically coupled to the switching circuit and configured to receive the switching signal to provide a primary current. The primary winding is coupled to the resonant circuit. The rectifying circuit is coupled to the secondary winding and configured to rectify a secondary current output by the secondary winding so as to provide an output voltage. The resonant circuit includes a variable inductor to adjust the characteristic curve of the converter.

Description

converter

This case relates to a converter, and in particular to a resonant converter.

The LLC resonant converter achieves a stable output voltage through frequency modulation. Recently, the LLC resonant converter is widely used in various applications due to its wide range of input voltages and high power output.

However, in the existing LLC resonant converter, when the load or operating conditions change, if the ratio of the magnetizing inductance to the resonant inductor is too large or too small, it cannot operate at the optimum operating point, resulting in a decrease in the efficiency of the converter. Applications are also limited.

One aspect of the present disclosure is a converter. The converter includes a switching circuit, a resonant circuit, a transformer, and a rectifier circuit. The switching circuit is configured to convert the DC input voltage into a switching signal. The resonant circuit is electrically connected to the switching circuit for receiving the switching signal to provide a primary current. The transformer includes a primary winding electrically connected to the resonant circuit; and a secondary winding. The rectifier circuit is electrically connected to the secondary winding of the transformer for rectifying a secondary current output of the secondary winding to provide an output voltage. The resonant circuit includes a variable inductor to adjust the characteristic curve of the converter.

In some embodiments of the present disclosure, the converter is configured to adjust an inductance value of the variable inductor to control a DC gain of the converter.

In some embodiments of the present disclosure, the resonant circuit includes: a resonant capacitor unit electrically connected to the primary winding in series; a resonant inductor unit electrically connected to the primary winding in series; and a The field magnetizing unit is electrically connected to the primary winding in parallel.

In some embodiments of the present disclosure, the resonant inductor unit and the field inductor unit include the variable inductor, and the resonant circuit adjusts the field magnetizing unit through the variable inductor. The inductance ratio of the resonant inductor unit.

In some embodiments of the present disclosure, the resonant inductor unit includes the variable inductor, and the resonant circuit adjusts a quality factor of the converter through the variable inductor.

In some embodiments of the present disclosure, the resonant inductor unit further includes a fixed inductor electrically coupled to the variable inductor in series or in parallel, and the core material of the fixed inductor is different. The core material of the variable inductor.

In some embodiments of the present disclosure, the fixed inductor includes a ferrite core inductor.

In some embodiments of the present disclosure, the magnetizing inductance unit includes the variable inductor.

In some embodiments of the present disclosure, the field inductor unit further includes a fixed inductor electrically coupled to the variable inductor in series or in parallel, and the core material of the fixed inductor Different from the core material of the variable inductor.

In some embodiments of the present disclosure, the fixed inductor includes a ferrite core inductor.

In some embodiments of the present disclosure, the variable inductor includes a magnetic powder core inductor whose magnetic permeability changes as the DC magnetic field strength changes.

In some embodiments of the present disclosure, the variable inductor includes a saturable core inductor.

In some embodiments of the present disclosure, the switching circuit includes: a first switch, a first end of the first switch is electrically coupled to a positive end of the DC input voltage, and a second end of the first switch Electrically coupled to the resonant circuit; and a second switch, a first end of the second switch is electrically coupled to the second end of the first switch, and a second end of the second switch is electrically The anode terminal is coupled to the DC input voltage.

In some embodiments of the present disclosure, the secondary winding of the transformer includes a first secondary winding and a second secondary winding, wherein a starting end of the second secondary winding is electrically coupled to the first The end of the secondary winding.

In some embodiments of the present disclosure, the rectifier circuit includes: a first diode, an anode end of the first diode is electrically coupled to a start end of the first secondary winding, the first diode a cathode end of the body is electrically coupled to a positive terminal of the output capacitor; and a second diode, an anode end of the second diode is electrically coupled to the end of the second secondary winding, a cathode end of the second diode is electrically coupled to the cathode end of the first diode; wherein an end of the first secondary winding is electrically coupled to a start end of the second secondary winding At a negative terminal of the output capacitor.

The embodiments are described in detail below to better understand the aspects of the present invention, but the embodiments are not intended to limit the scope of the disclosure, and the description of the structural operation is not limited. The order in which they are performed, any device that is recombined by components, produces equal devices, and is covered by this disclosure. In addition, according to industry standards and practices, the drawings are only for the purpose of assisting the description, and are not drawn according to the original size. In fact, the dimensions of the various features may be arbitrarily increased or decreased for convenience of explanation. In the following description, the same elements will be denoted by the same reference numerals for explanation.

The terms used in the entire specification and the scope of the patent application, unless otherwise specified, generally have the ordinary meaning of each term used in the field, the content disclosed herein, and the particular content. Certain terms used to describe the disclosure are discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in the description of the disclosure.

In addition, the terms "including", "including", "having", "containing", and the like, as used herein, are all open terms, meaning "including but not limited to". Further, "and/or" as used herein includes any one or combination of one or more of the associated listed items.

As used herein, when an element is referred to as "connected" or "coupled", it may mean "electrically connected" or "electrically coupled". "Connected" or "coupled" can also be used to indicate that two or more components operate or interact with each other. In addition, although the terms "first", "second", and the like are used herein to describe different elements, the terms are used only to distinguish the elements or operations described in the same technical terms. The use of the term is not intended to be a limitation or a

Please refer to Figure 1. FIG. 1 is a schematic diagram of a converter 100 according to some embodiments of the present disclosure. As shown in FIG. 1, in some embodiments, the converter 100 includes a switching circuit 120, a resonant circuit 140, a transformer 160, a rectifier circuit 180, and an output capacitor Co.

Structurally, the input end of the switching circuit 120 is electrically coupled to the DC voltage source 110 for receiving the DC input voltage Vin. The output end of the switching circuit 120 is electrically coupled to the input end of the resonant circuit 140 for outputting the switching signal Sig1 converted by the DC input voltage Vin through the switching circuit 120 to the resonant circuit 140. The output end of the resonant circuit 140 is electrically coupled to the primary side of the transformer 160. The input end of the rectifier circuit 180 is electrically coupled to the secondary side of the transformer 160. The output end of the rectifier circuit 180 is electrically coupled to the output capacitor Co to provide a DC output voltage Vo to the subsequent stage circuit. In this way, the switching circuit 120, the resonant circuit 140, the transformer 160, and the rectifier circuit 180 can form the circuit architecture of the LLC resonant converter.

Specifically, in some embodiments, the primary side of the transformer 160 includes a set of primary windings Np. The secondary side of the transformer 160 includes two sets of secondary windings Ns1 and Ns2, wherein the starting end of the secondary winding Ns2 is electrically coupled to the end of the secondary winding Ns1 and is electrically coupled to the negative terminal of the output capacitor Co. . For example, in some embodiments, the transformer 160 may be a secondary side center tapped transformer to divide the secondary side of the transformer 160 into a secondary winding Ns1 and a secondary winding Ns2 coupled to each other. In some embodiments, the transformer 160 can also be a transformer with only one set of secondary windings on the secondary side, and with a full bridge rectifier circuit, the secondary side and its rectifier circuit can be completed according to any form known to those skilled in the art.

In some embodiments, the switching circuit 120 in the converter 100 can adopt a half bridge architecture to implement a half bridge resonant converter, but the present invention is not limited thereto. As shown in FIG. 1, in some embodiments, the switching circuit 120 includes a switch S1 and a switch S2. The first end of the switch S1 is electrically coupled to the positive terminal of the DC input voltage Vin, and the second end of the switch S1 is electrically coupled to the resonant circuit 140. The first end of the switch S2 is electrically coupled to the second end of the switch S1, and the second end of the switch S2 is electrically coupled to the negative end of the DC input voltage Vin. The control terminals of the switch S1 and the switch S2 are respectively configured to receive the driving signals CS1 and CS2, so that the switch S1 and the switch S2 are selectively turned on or off according to the driving signals CS1 and CS2.

Therefore, the switching circuit 120 can selectively turn on the switch S1 and the switch S2 to output the switching signal Sig1 having a high level (eg, the input voltage Vin) when the switch S1 is turned on, and is turned on at the switch S2. The switching signal Sig1 having a low level (eg, zero potential) is output. For example, in a complete switching cycle, the driving signals CS1 and CS2 can be pulse frequency modulation (PFM) signals, and the switches S1 and S2 can be turned on for half a cycle respectively, so that the output duty cycle is 50%. Switching signal Sig1. In addition, in other embodiments, the switching circuit 120 can also employ a full bridge architecture to implement a full bridge resonant converter. For example, the switching circuit 120 can also include two pairs of switches in pairs, and the switches are selectively turned on or off by receiving corresponding driving signals. In this way, in a complete cycle, the switching circuit 120 can turn on one of the switches according to the driving signal in the first half cycle, turn off the other pair of switches to output the switching signal Sig1 having a positive potential, and according to the driving signal in the second half cycle. The switch is turned on and off to output a switching signal Sig1 having a negative level.

In some embodiments, the resonant circuit 140 includes a resonant capacitor unit 142, a resonant inductor unit 144, and a magnetizing inductor unit 146, but the present invention is not limited thereto. Structurally, the resonant capacitor unit 142, the resonant inductor unit 144, and the primary winding Np of the transformer 160 are connected in series with each other. The field inductance unit 146 and the primary winding Np of the transformer 160 are connected in parallel with each other. For example, as shown in FIG. 1, the first end of the resonant capacitor unit 142 is electrically connected to the first end of the resonant circuit 140 to be electrically connected to the second end of the switch S1 and the first end of the switch S2. The second end of the resonant capacitor unit 142 is electrically connected to the first end of the resonant inductor unit 144. The second end of the resonant inductor unit 144 is electrically connected to the first end of the magnetizing inductance unit 146. The second end of the magnetizing inductance unit 146 is electrically connected to the second end of the resonant circuit 140 to be electrically connected to the negative terminal of the DC input voltage Vin, but the disclosure is not limited thereto. In some embodiments, the resonant inductor unit 144 and the magnetizing inductor unit 146 can respectively include the leakage inductance and magnetizing inductance of the transformer 160. In other embodiments, the resonant capacitor unit 142, the resonant inductor unit 144, and the magnetizing inductor unit 146 can also be electrically connected in different manners to implement an LLC resonant circuit. In addition, in other embodiments, the resonant circuit 140 can also implement an LC resonant circuit, an LCC resonant circuit, and an LLCC resonant circuit by one or more sets of inductive units and capacitor units. Therefore, the LLC resonant circuit illustrated in the drawings herein It is only one of the possible implementation methods of this case and is not intended to limit the case. In other words, those skilled in the art will understand that the resonant circuit 140 in various embodiments of the present invention may be any combination of one or more sets of inductive units and one or more sets of capacitive units, and may be electrically connected in different ways, such as in series or in parallel. Connect to achieve resonance.

Specifically, any one of the resonant inductor unit 144 and the magnetizing inductor unit 146 in the resonant circuit 140 includes a variable inductor, and the resonant circuit 140 adjusts the magnetizing and inducting unit 146 and the resonant inductor through the variable inductor. The inductance ratio of unit 144, thereby adjusting the characteristic curve of converter 100. The details will be explained in the subsequent paragraphs with the corresponding drawings.

As shown in FIG. 1 , in some embodiments, the rectifier circuit 180 is electrically connected to the secondary winding Ns1 and the secondary winding Ns2 of the transformer 160 for sensing the primary winding Np of the secondary winding Ns1 and the secondary winding Ns2. The secondary current Is outputted by the change of the upper signal is rectified to provide an output voltage Vo across the output capacitor Co.

In some embodiments, the rectifier circuit 180 includes a diode D1 and a diode D2. Structurally, the anode end of the diode D1 is electrically coupled to the start end of the secondary winding Ns1. The cathode end of the diode D1 is electrically coupled to the positive terminal of the output capacitor Co. The anode end of the diode D2 is electrically coupled to the end of the secondary winding Ns2. The cathode end of the diode D2 is electrically coupled to the cathode end of the diode D1.

Thereby, the DC output voltage Vo can be supplied by rectifying and filtering the electric signals sensed and outputted by the rectifying circuit 180 and the output capacitor Co to the secondary windings Ns1 and Ns2.

In this way, through the operation of the above circuit, the converter 100 can convert the DC input voltage Vin into a DC output voltage Vo having an appropriate voltage level to be supplied to the subsequent stage circuit.

Please refer to Figure 2 and Figure 3 together. 2 and 3 are schematic diagrams showing the operation of the converter 100 according to some embodiments of the present disclosure. In FIGS. 2 and 3, similar elements related to the embodiment of FIG. 1 are denoted by the same reference numerals for ease of understanding, and the specific principles of the similar elements have been described in detail in the preceding paragraphs, if not necessary. This will not be repeated here.

As shown in FIG. 2, in the upper half cycle, the switch S1 receives the drive signal CS1 having the enable level and is turned on. The primary winding Np is subjected to a forward voltage, the resonant capacitor unit 142 and the resonant inductor unit 144 participate in resonance, and the energy is transmitted to the secondary winding Ns1 through the transformer 160, and finally the current is output via the turned-on diode D1.

As shown in FIG. 3, in the second half cycle, the switch S2 receives the drive signal CS2 having the enable level and is turned on. As the switching signal Sig1 falls to zero, the primary winding Np is subjected to a reverse voltage, the resonant capacitor unit 142 and the resonant inductor unit 144 participate in resonance, and the energy is transmitted to the secondary winding Ns2 through the transformer 160, and finally via the turned-on diode. D2 output current.

For the circuit architecture of the LLC resonant converter illustrated in FIGS. 1 to 3, the resonant frequency, the quality factor, and the DC gain of the converter 100 can be expressed as the following equations, respectively. .

among them Represents the resonant frequency, Representing the sense value of the resonant inductor unit 144, Represents the capacitance of the resonant capacitor unit 142. n represents the turns ratio of the primary winding Np and the secondary windings Ns1, Ns2. Indicates the load resistance. Indicates DC gain. Indicates the inductance ratio of the magnetizing inductance unit 146 and the resonant inductor unit 144 (ie, / ). Represents the normalized frequency (ie: switching frequency) And resonant frequency Ratio / ).

It can be known from the above formulas that the resonant frequency of the converter 100 And the quality factor Q and the inductance of the resonant inductor unit 144 related. When the inductance of the resonant inductor unit 144 The larger the quality factor Q, the higher the resonance frequency The lower. In contrast, when the inductance of the resonant inductor unit 144 The smaller the quality factor Q, the smaller the resonance frequency The higher.

On the other hand, the DC gain of the converter 100 It can be expressed as the inductance ratio h of the magnetizing inductance unit 146 and the resonant inductor unit 144, the quality factor Q, and the normalized frequency. The function. Therefore, the DC gain of the converter 100 Sensing value with the resonant inductor unit 144 The inductance of the magnetizing inductance unit 146 related.

Operationally, the switching frequency of the resonant converter Usually designed at resonant frequency Nearby to get better conversion efficiency and maintain switching frequency The overall operating range is within a certain range so that the losses of the converter 100 can be maintained at a low level under various operating conditions. Therefore, by setting the sense value of the resonant inductor unit 144 Sensing value with the magnetizing inductance unit 146 Variable in circuit operation, you can adjust h value, quality factor Q, resonant frequency To optimize the operating characteristics of the converter 100 and achieve an ideal operating point on the characteristic curve.

Please refer to FIG. 4A, FIG. 4B and FIG. 4C. 4A, 4B, and 4C are DC gains according to some embodiments of the present disclosure. Regularization frequency Schematic diagram of the relationship. In Figures 4A, 4B, and 4C, the horizontal axis represents the normalized frequency. , the vertical axis represents DC gain . When the inductance ratio h of the magnetizing inductance unit 146 and the resonant inductor unit 144 is fixed at 4, the curves L1, L2, L3, and L4 correspond to the quality factor Q of 0.1, 0.2, 0.4, and 0.8, respectively. DC gain Regularization frequency Relationship. 4B shows that the inductance ratio h of the magnetizing inductance unit 146 and the resonant inductor unit 144 is fixed at 6, and the curves L5, L6, L7, and L8 correspond to the quality factor Q of 0.1, 0.2, 0.4, and 0.8, respectively. Gain Regularization frequency Relationship. In Fig. 4C, when the quality factor is fixed at 0.3, the curves L9, L10, L11, and L12 correspond to the inductance ratio h, which is 2, 4, 6, and 8, respectively. Regularization frequency Relationship.

It is worth noting that the specific parameter values in Figures 4A, 4B, and 4C and the characteristic curves shown are only examples to illustrate the DC gain. Inductance ratio h, quality factor Q, and normalized frequency The relevance is not intended to limit the case.

As shown in Figures 4A and 4B. When the inductance ratio h of the magnetizing inductance unit 146 and the resonant inductor unit 144 is large, the converter 100 has a smaller maximum DC gain value for a curve having the same quality factor Q (eg, in the case of the same load). . For example, when the quality factor is maintained at 0.1, when the inductance ratio h is 4, the maximum value of the curve is greater than 5. In contrast, when the inductance ratio h is 6, the maximum value of the curve is between 4 and 5.

In addition, when the inductance ratio h of the magnetizing inductance unit 146 and the resonant inductor unit 144 is large, the normalized frequency corresponding to the maximum DC gain value Smaller. In contrast, when the inductance ratio h of the magnetizing inductance unit 146 and the resonant inductor unit 144 is small, the normalized frequency corresponding to the maximum DC gain value Larger. In other words, when the inductance ratio h of the magnetizing inductance unit 146 and the resonant inductor unit 144 is large, the switching frequency is to be operated when the same DC gain output is to be operated. Farther away from the resonant frequency of the converter 100 In turn, affecting the overall efficiency of the converter 100.

In addition, it can also be seen from the 4A and 4B diagrams that the switching frequency Less than the resonant frequency In the operating region, when the inductance ratio h of the magnetizing inductance unit 146 and the resonant inductor unit 144 is large, the converter 100 operates at the same switching frequency. Converter 100 also has a small DC gain .

It can also be seen from FIG. 4C that when the quality factor Q is maintained at a certain value and the inductance ratio h of the magnetizing inductance unit 146 and the resonant inductor unit 144 is changed, the maximum DC gain is larger for the larger value of h. Smaller value, and when normalized frequency With switching frequency DC gain when increasing The change is relatively flat, which in turn causes the load to be under light load conditions, and the output voltage Vo may not be controlled to an appropriate voltage level.

However, for a smaller value of h, the magnetizing inductance unit 146 is relatively small, resulting in a larger field current, and thus may increase the switching loss of the switch, so the selection of the value of h often fails to satisfy all conditions. In other words, it can be seen from the characteristic diagrams of FIG. 4A, FIG. 4B, and FIG. 4C that if the inductance values of the resonant inductor unit 144 and the magnetizing inductance unit 146 are constant values, the load condition and the working condition cannot be used. The difference adjustment characteristic curve results in a decrease in the efficiency of the converter 100 or a limitation in the application.

Therefore, in some embodiments of the present disclosure, the resonant inductor unit 144 and the magnetizing inductance unit 146 include at least one variable inductor. Thereby, the resonant circuit 140 can adjust the inductance ratio h of the magnetizing inductance unit 146 and the resonant inductor unit 144 through the variable inductor. As such, the converter 100 can control the maximum DC gain of the converter 100 by adjusting the inductance of the variable inductor.

In addition, in the embodiment where the resonant inductor unit 144 includes a variable inductor, the resonant circuit 140 can further adjust the quality factor Q of the converter 100 and the excitation inductor unit 146 and the resonant inductor unit 144 through the variable inductor. The inductance ratio h is used to adjust the output characteristics of the converter 100.

For example, in a voltage adjustable application, the DC gain of converter 100 may be insufficient or the switching frequency needs to be greatly reduced. To increase the gain. According to some embodiments of the present disclosure, the converter 100 can reduce the inductance ratio of the magnetizing inductance unit 146 and the resonant inductor unit 144 by adjusting the inductance value of the variable inductor, thereby obtaining a higher output voltage. Vo.

Various embodiments of the variable inductor provided in the resonant circuit 140 will be described in the following paragraphs in conjunction with the drawings. Please refer to pictures 5A to 5D. 5A-5D are schematic diagrams of a resonant circuit 140 according to some embodiments of the present disclosure.

In the embodiment shown in FIGS. 5A to 5D, the inductance ratio h of the field inductance unit 146 and the resonance inductance unit 144 can be adjusted by providing the variable inductance Lm in the field inductance unit 146. As shown in FIG. 5A, in some embodiments, the resonant inductor unit 144 can include a fixed inductor Ls, and the magnetizing inductor unit 146 can include a variable inductor Lm. For example, in some embodiments, the variable inductor Lm can be a magnetic powder core inductor. For example, molybdenum permalloy magnetic powder cores (MPP Cores) containing iron, nickel, and molybdenum, high flux cores containing iron-nickel alloy powder, and magnetic cores containing iron-bismuth aluminum alloy powder (Kool Mu/Sendust Cores), Mega Flux core with iron-bismuth alloy powder, etc., but this is not limited to this case.

The magnetic permeability (Permeability) of the variable inductor Lm using the above magnetic powder core changes with the DC bias magnetic field strength, so the inductance value changes with the magnitude of the flowing current, and is different. The magnetic powder core also has different rates of change.

As shown in FIG. 5B and FIG. 5C , in some embodiments, the magnetizing inductance unit 146 may include a fixed inductor Lm1 and a variable inductor Lm2 electrically coupled to each other such that the exciting inductor unit 146 is integral. The inductance value is variable. As shown in FIG. 5B, the fixed inductor Lm1 and the variable inductor Lm2 in the magnetizing inductance unit 146 are connected in series to each other. As shown in FIG. 5C, the fixed inductor Lm1 and the variable inductor Lm2 in the magnetizing inductance unit 146 are connected in parallel with each other. It is worth noting that the fixed inductance described here only represents a fixed inductance value within the load variation range, as long as the fixed inductance is maintained within the load variation range as a fixed inductance.

For example, in the embodiment shown in FIGS. 5B and 5C, the fixed inductor Lm1 may be a powdered ferrite core. In other words, the fixed inductor Lm1 uses a magnetic core material that is different from the magnetic core material used in the variable inductor Lm2. In the embodiment shown in FIGS. 5B and 5C, the rate of change of the entire magnetizing inductance can be further adjusted by the ratio of the distribution of the fixed inductor Lm1 and the variable inductor Lm2. For example, in Figure 5B, if a large change in the magnetizing inductance is required, the distribution ratio of Lm2 can be increased; if only a slight change in the magnetizing inductance is required, the distribution ratio of Lm2 can be reduced, thereby optimizing the line.

As shown in FIG. 5D, in some embodiments, the variable inductor Lm2 in the magnetizing inductance unit 146 may also be a saturable core inductor. By varying the current flowing through the saturable core inductor, the inductance of the saturable core inductor can be changed. In this way, the resonant circuit 140 can change the inductance ratio h of the magnetizing inductance unit 146 and the resonant inductor unit 144 through the magnetic saturation characteristic of the saturable core.

Please refer to pictures 6A to 6D. 6A-6D are schematic diagrams of a resonant circuit 140 according to other embodiments of the present disclosure. In the embodiment illustrated in FIGS. 6A to 6D, the variable inductor Ls or Ls2 is disposed in the resonant inductor unit 144, as compared with the embodiment illustrated in FIGS. 5A-5D. The inductance ratio h of the magnetizing inductance unit 146 and the resonant inductor unit 144 is adjusted. In addition, due to the resonant frequency of the converter 100 The quality factor Q is related to the sense value of the resonant inductor unit 144. Therefore, the resonant frequency of the converter 100 can also be adjusted through the variable inductor Ls or Ls2 provided in the resonant inductor unit 144. With quality factor Q. For example, when the load is light, the current flowing through the resonant inductor unit 144 will be small. At this time, the variable inductor Ls or Ls2 has a large inductance value, and the converter 100 has a large quality factor Q. The ratio h to the smaller inductance helps the output voltage Vo to be controlled at the appropriate voltage level.

As shown in FIG. 6A, in some embodiments, the magnetizing inductance unit 146 can include a fixed inductor Lm, and the resonant inductor unit 144 can include a variable inductor Ls. Similarly, in some embodiments, the variable inductor Ls in the resonant inductor unit 144 can be various types of magnetic powder core inductors, which are described in detail in the previous paragraphs, and thus will not be described again.

As shown in FIG. 6B and FIG. 6C, in some embodiments, the resonant inductor unit 144 may include a fixed inductor Ls1 and a variable inductor Ls2 electrically coupled to each other such that the inductance value of the resonant inductor unit 144 as a whole is obtained. variable. As shown in FIG. 6B, the fixed inductor Ls1 and the variable inductor Ls2 in the resonant inductor unit 144 are connected in series to each other. As shown in FIG. 6C, the fixed inductor Ls1 and the variable inductor Ls2 in the resonant inductor unit 144 are connected in parallel with each other. Similarly, the fixed inductor Ls1 may be a powdered ferrite core. In other words, the fixed inductor Ls1 uses a magnetic core material that is different from the magnetic core material used in the variable inductor Ls2. The distribution ratio of the fixed inductor Ls1 and the variable inductor Ls2 can also be adjusted, similar to the description in the previous paragraph, and thus will not be described herein.

As shown in FIG. 6D, in some embodiments, the variable inductor Ls2 in the resonant inductor unit 144 can also be a saturable core inductor. By varying the current flowing through the saturable core inductor, the inductance of the saturable core inductor can be changed. In this way, the resonant circuit 140 can change the inductance ratio h of the magnetizing inductance unit 146 and the resonant inductor unit 144 through the magnetic saturation characteristic of the saturable core.

In addition, it should be noted that, in the case of no conflict, the magnetizing inductance unit 146 illustrated in FIGS. 5A to 5D and the resonant inductor unit 144 illustrated in FIGS. 6A to 6D may also be used. Combine with each other. The circuits illustrated in the drawings are for illustrative purposes only and are simplified for simplicity and ease of understanding and are not intended to limit the present invention.

In other words, as shown in FIG. 7 , in some embodiments, the resonant inductor unit 144 and the magnetizing inductor unit 146 may respectively include the variable inductor Ls and the variable inductor Lm, or may be connected in series or in parallel with each other. The fixed inductor Ls1, the variable inductor Ls2, and the fixed inductor Lm1 and the variable inductor Lm2 connected in series or in parallel with each other. It should be noted that when the resonant inductor unit 144 and the magnetizing inductor unit 146 respectively include the variable inductor Ls and the variable inductor Lm, the variable inductor Ls and the variable inductor Lm can be adjusted. There are different rates of change to meet the needs of various applications, and the magnetic core materials and related operations employed have been described in detail in the previous embodiments, and thus will not be described again.

In summary, by providing the resonant circuit of the variable inductor in the resonant inductor unit or/and the field magnetizing unit in the above embodiments, the field magnetizing unit and the resonant inductor unit can be automatically adjusted according to the load. The inductance ratio is at an appropriate size to obtain different output characteristics of the converter. In addition, in some embodiments, the resonant frequency and the quality factor of the converter can be adjusted to obtain different output characteristic curves of the converter.

The present disclosure has been disclosed in the above embodiments, and is not intended to limit the disclosure, and the present disclosure may be variously modified and retouched without departing from the spirit and scope of the present disclosure. The scope of protection of the content is subject to the definition of the scope of the patent application.

100‧‧‧ converter

110‧‧‧DC voltage source

120‧‧‧Switching circuit

140‧‧‧Resonance circuit

142‧‧‧Resonant capacitor unit

144‧‧‧Resonant Inductance Unit

146‧‧‧Excitation Inductance Unit

160‧‧‧Transformers

180‧‧‧Rectifier circuit

Co‧‧‧ output capacitor

Np‧‧‧ primary winding

Ns1, Ns2‧‧‧ secondary winding

S1, S2‧‧‧ switch

D1, D2‧‧‧ diode

CS1, CS2‧‧‧ drive signals

Sig1‧‧‧Switching signal

Vin‧‧‧Input voltage

Vo‧‧‧ output voltage

L1～L12‧‧‧ Curve

Ls, Ls1, Ls2, Lm, Lm1, Lm2‧‧‧ inductors

1 is a schematic diagram of a converter depicted in accordance with some embodiments of the present disclosure. 2 and 3 are schematic diagrams showing the operation of the converter according to some embodiments of the present disclosure. 4A, 4B, and 4C are diagrams showing the relationship between the DC gain and the normalized frequency according to some embodiments of the present disclosure. 5A-5D are schematic diagrams of a resonant circuit according to some embodiments of the present disclosure. 6A-6D are schematic diagrams of a resonant circuit according to other embodiments of the present disclosure. FIG. 7 is a schematic diagram of a resonant circuit according to other embodiments of the present disclosure.

Claims (15)

A converter comprising: a switching circuit for converting a DC input voltage into a switching signal; a resonant circuit electrically coupled to the switching circuit for receiving the switching signal to provide a primary current; The method includes: a primary winding electrically connected to the resonant circuit; a secondary winding; and a rectifier circuit electrically connected to the secondary winding of the transformer for outputting a secondary side of the secondary winding The current is rectified to provide an output voltage; wherein the resonant circuit includes a variable inductor to adjust the characteristic curve of the converter. The converter of claim 1, wherein the converter is configured to adjust an inductance value of the variable inductor to control a DC gain of the converter. The converter of claim 1, wherein the resonant circuit comprises: a resonant capacitor unit electrically connected in series to the primary winding; a resonant inductor unit electrically connected in series to the primary winding; And a field inductive unit electrically connected to the primary winding in parallel. The converter of claim 3, wherein the resonant inductor unit and the magnetizing inductor unit comprise the variable inductor, and the resonant circuit adjusts the field magnetizing unit through the variable inductor The ratio of the inductance to the resonant inductor unit. The converter of claim 3, wherein the resonant inductor unit comprises the variable inductor, and the resonant circuit adjusts a quality factor of the converter through the variable inductor. The converter of claim 5, wherein the resonant inductor unit further comprises a fixed inductor electrically coupled to the variable inductor in series or in parallel, the core of the fixed inductor The material is different from the core material of the variable inductor. The converter of claim 6 wherein the fixed inductor comprises a ferrite core inductor. The converter of claim 3, wherein the magnetizing inductance unit comprises the variable inductor. The converter of claim 8, wherein the excitation inductor unit further comprises a fixed inductor electrically coupled to the variable inductor in series or in parallel, the magnetic of the fixed inductor The core material is different from the core material of the variable inductor. The converter of claim 9, wherein the fixed inductor comprises a ferrite core inductor. The converter of claim 1, wherein the variable inductor comprises a magnetic powder core inductor whose magnetic permeability changes as the strength of the DC magnetic field changes. The converter of claim 1 wherein the variable inductor comprises a saturable core inductor. The converter of claim 1, wherein the switching circuit comprises: a first switch, a first end of the first switch is electrically coupled to a positive terminal of the DC input voltage, and a first switch The second end is electrically coupled to the resonant circuit; and a second switch, a first end of the second switch is electrically coupled to the second end of the first switch, and a second end of the second switch Electrically coupled to the negative terminal of the DC input voltage. The converter of claim 1, wherein the secondary winding of the transformer comprises a first secondary winding and a second secondary winding, wherein a starting end of the second secondary winding is electrically coupled to the The end of the first secondary winding. The converter of claim 14, wherein the rectifier circuit comprises: a first diode, an anode end of the first diode is electrically coupled to a start end of the first secondary winding, the first a cathode end of the diode is electrically coupled to a positive terminal of an output capacitor; and a second diode, an anode end of the second diode is electrically coupled to the end of the second secondary winding a cathode end of the second diode is electrically coupled to the cathode end of the first diode; wherein an end of the first secondary winding and an initial end of the second secondary winding The first end of the output capacitor is coupled to the negative terminal.