阅读说明：本技术 谐振转换器及dc/dc功率转换器 (Resonant converter and DC/DC power converter ) 是由 魏宏彬 于 2019-01-02 设计创作，主要内容包括：本申请公开了一种谐振转换器,包括输入切换网络,用于提供输入脉冲波形；和谐振网络,其包括接收所述输入切换网络输出的脉冲波形的谐振电容,与所述谐振电容串联的第一电感,感值小于10mH的第二电感,所述第二电感一端连接所述第一电感,一端与所述输入切换网络形成回路,以及与所述第二电感并联或等效并联的容性元件,其中,所述谐振转换器通过所述谐振网络为与所述第二电感并联或等效并联的负载供电。(A resonant converter includes an input switching network for providing an input pulse waveform; and the resonant network comprises a resonant capacitor for receiving a pulse waveform output by the input switching network, a first inductor connected with the resonant capacitor in series, a second inductor with an inductance value smaller than 10mH, one end of the second inductor is connected with the first inductor, one end of the second inductor forms a loop with the input switching network, and a capacitive element connected with the second inductor in parallel or equivalent parallel, wherein the resonant converter supplies power to a load connected with the second inductor in parallel or equivalent parallel through the resonant network.)

1. A resonant converter, comprising:

an input switching network for providing an input pulse waveform; and

the resonant converter comprises a resonant network, a first inductor, a second inductor and a capacitive element, wherein the resonant network comprises a resonant capacitor for receiving a pulse waveform output by the input switching network, the first inductor is connected with the resonant capacitor in series, the second inductor is less than 10mH in inductance value, one end of the second inductor is connected with the first inductor, one end of the second inductor forms a loop with the input switching network, and the capacitive element is connected with the second inductor in parallel or in equivalent parallel, and the resonant converter supplies power to a load which is connected with the second inductor in parallel or in equivalent parallel through the resonant network.

2. The resonant converter of claim 1, wherein the inductance of the second inductor is between 1mH and 2 mH.

3. The resonant converter of claim 2, wherein the resonant network further comprises a transformer, wherein the second inductance is an excitation inductance of the transformer.

4. A resonant converter according to claim 3, wherein the capacitive element is connected in parallel to the primary or secondary side of the transformer.

5. The resonant converter of claim 3, wherein the first inductance is an integrated inductance or a separate inductance of the transformer.

6. A resonant converter according to claim 3, wherein the secondary side of the transformer is for connection to a load.

7. A DC/DC power converter, comprising:

the input switching network is used for receiving a direct current power supply and providing an input pulse waveform;

a resonant network including a resonant capacitor receiving an output pulse waveform of the input switching network, a first inductor connected in series with the resonant capacitor, and a transformer having an excitation inductor of less than 10mH, one end of the excitation inductor being connected to the first inductor and the other end forming a loop with the input switching network, wherein the resonant network further includes a capacitive element connected in parallel with the excitation inductor or in parallel with a secondary side of the transformer; and

and the rectifying circuit is connected to the secondary side of the transformer and used for rectifying the output of the transformer and then supplying power to a load.

8. The power converter of claim 7, wherein the inductance of the excitation inductance is between 1mH and 2 mH.

9. The power converter of claim 7, wherein the first inductance is an integrated inductance or a separate inductance of the transformer.

10. The power converter of claim 7, wherein the resonant network includes clamping diodes respectively connected between the transformer primary side and the input switching network.

Technical Field

The present disclosure relates generally to power supply systems, and more particularly to resonant converters and DC/DC power converters of power supply systems.

Background

A converter operating in a resonant mode (where the impedance between the input and output of the circuit is minimal) may provide higher efficiency LL C and L CC resonant converters are widely used in the power electronics industry, LL C and L CC are widely used in the lighting industry for DC/DC converters due to their high efficiency and some advanced functionality.

However, both LL C and L CC have their weaknesses when the output voltage range is large (e.g., 2-4 times the gain range). for LL C, a narrow operating frequency range can be designed to cover a wide output range. if zVS and zcS of the output range are to be maintained, this will greatly reduce the efficiency of the full voltage load (typically, the efficiency will be reduced by 2-3%). for L CC, the efficiency under full voltage load is high because the excitation inductance of its transformer tends to infinity, but the operating frequency range must be large to cover a wide output range. for example, at 60KHz at full output voltage, the frequency increases to >300kHz at 1/3 output voltage, and particularly for deep dimming applications, the frequency will be higher than 400kHz when the dimming depth is < 5%, which is unacceptable from an engineering standpoint.

It would be desirable to provide a novel resonant converter that overcomes the disadvantages of the LL C and L CC resonant converters, which should have higher efficiency and narrower frequency ranges, and be suitable for wide output voltage range and deep dimming applications.

Disclosure of Invention

In one embodiment, the present application discloses a resonant converter comprising an input switching network for providing an input pulse waveform; and the resonant network comprises a resonant capacitor for receiving a pulse waveform output by the input switching network, a first inductor connected with the resonant capacitor in series, a second inductor, one end of the second inductor is connected with the first inductor, one end of the second inductor forms a loop with the input switching network, and a capacitive element connected with the second inductor in parallel or equivalent parallel, wherein the resonant converter supplies power to a load connected with the second inductor in parallel or equivalent parallel through the resonant network.

In one embodiment, the present application further discloses a DC/DC power converter comprising an input switching network for receiving a DC power source and providing an input pulse waveform; a resonant network including a resonant capacitor receiving an output pulse waveform of the input switching network, a first inductor connected in series with the resonant capacitor, and a transformer having an excitation inductor of less than 10mH, one end of the excitation inductor being connected to the first inductor and the other end forming a loop with the input switching network, wherein the resonant network further includes a capacitive element connected in parallel with the excitation inductor or in parallel with a secondary side of the transformer; and the rectifying circuit is connected to the secondary side of the transformer and used for rectifying the output of the resonant network and then supplying power to the load.

Drawings

These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

FIG. 1 is a schematic diagram of a DC/DC power converter including a resonant converter according to one embodiment of the present invention;

FIG. 2 is an equivalent circuit schematic of a resonant converter according to one embodiment of the present invention;

FIG. 3 is a further equivalent circuit schematic of a resonant converter according to one embodiment of the present invention;

FIG. 4 is a schematic diagram of a DC/DC power converter including a resonant converter according to yet another embodiment of the present invention;

FIG. 5 is an equivalent circuit schematic of a resonant converter according to yet another embodiment of the present invention;

fig. 6 is a schematic diagram of a gain curve of a resonant converter in accordance with one embodiment of the present invention.

Detailed Description

To assist those skilled in the art in understanding the claimed subject matter, a detailed description of the invention is provided below along with accompanying figures. In the following detailed description of the embodiments, well-known functions or constructions are not described in detail in order to avoid unnecessarily obscuring the present disclosure.

Unless otherwise defined, technical or scientific terms used in the claims and the specification should have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. As used in this specification and the appended claims, the terms "first," "second," and the like do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The terms "a" or "an," and the like, do not denote a limitation of quantity, but rather denote the presence of at least one. Unless otherwise indicated, the terms "front," "back," "lower," and/or "upper" and the like are used for convenience of description and are not limited to one position or one spatial orientation. The word "or" and the like are meant to be inclusive and mean one or all of the listed items. The word "comprising" or "having", and the like, means that the element or item appearing before "comprises" or "having" covers the element or item listed after "comprising" or "having" and its equivalent, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections or couplings, whether direct or indirect.

As shown in fig. 1, the present application discloses a DC/DC power converter including a resonant converter 10 and an output network 13. The resonant converter 10 comprises an input switching network 11 and a resonant network 12. The input switching network 11 may receive direct current and provide an input pulse waveform, which may include a square wave generator. The square wave generator may comprise a full or half bridge circuit topology with at least two thyristors to convert the dc input voltage into a square wave waveform which is then fed into the resonant network 12. The square waveform is composed of a sinusoidal fundamental wave and a series of higher order harmonics. In the preliminary analysis, the square waveform can be approximated as a fundamental wave, ignoring the effects of higher order harmonics. In fig. 1, the square wave generator is two thyristors Q1 and Q2 in series, one side of the resonant network 12 being connected to the midpoint of Q1 and Q2 and the other end of Q2, respectively. Q1 and Q2 each have a 50% duty cycle, which in turn provide a square waveform input to the resonant network 12.

The resonant network 12 comprises a resonant capacitor Cs, a first inductor L s, a transformer 14 having an excitation inductor L m, and a capacitor Cr. connected in parallel with the secondary side of the transformer, wherein Cs is a series resonant capacitor, L s is an integrated inductor of the transformer, and in other embodiments may be a separate inductor, L m is less than 10mH, and may specifically be any value less than 10mH, preferably ranging between 1mH and 2mH, wherein energy is transferred between the Cs, Cr, L s, and L m to form a resonance, the resonant converter further comprises diodes D5 and D6, wherein the point is located between L s and L m, and the two sides are connected to the two ends of the input switching network, i.e., Q1 and Q2, respectively, the diodes D5 and D6 are clamping diodes, one end of which is connected to the primary side of the transformer, and the other end of which is connected to the two ends of Q1 and Q2, respectively, and may function as a clamping dc isolation for the primary side of the transformer, Cb connected between the input switching loop L m and the dc isolation.

The output network 13 comprises a rectifying circuit, which may be a full-bridge or half-bridge diode topology, which in the example of fig. 1 comprises series connected D1 and D2, and series connected D3 and D4, wherein D1 and D2 are connected in parallel with D3 and D4. The secondary side of the transformer has one end connected to the midpoints of D1 and D2 and the other end connected to the midpoints of D3 and D4. The output of the rectifying circuit is connected with a load to provide direct current voltage for the load. The rectifier circuit also includes a capacitor Co connected in parallel with the load to provide a function of storing energy. In other embodiments, the rectifier circuit may also be implemented by a thyristor circuit topology.

FIG. 2 is the equivalent circuit of FIG. 1. As can be seen from FIG. 2, the resonant network 12 includes a resonant capacitor Cs in series with the input switching network 11, a first inductor L s, and a second inductor L m, where L m is less than 10mH, preferably, L m ranges between 1mH and 2 mH. also includes a capacitive element, such as a capacitor Cr, in parallel or equivalent with the second inductor L m. Rac is the equivalent load in parallel with L m and has a value of 1mHThe transformer 14 and its magnetizing inductor L m in fig. 1 are connected to the negative pole of the power supply via a capacitor Cb, in fig. 3, since Cb is much larger than Cs, the equivalent circuit of fig. 2 is further simplifiedInto a circuit as shown in fig. 3. Wherein the energy is in the Cs, Cr/N²and L s and L m to form resonance.

In another embodiment, as shown in FIG. 4, a capacitor Cr is connected on the primary side of the transformer in parallel with the exciting inductor L m of the transformer, wherein L m is less than 10mH, preferably L m ranges between 1mH and 2mH, and likewise, since Cb is much larger than Cs, the equivalent circuit of FIG. 4 is further simplified to the circuit shown in FIG. 5.

The advantages of the aforementioned resonant converter can be confirmed by the voltage gain diagram described in fig. 6, wherein the resonance parameters of the resonant network are defined as follows,

where fsw is the operating frequency, fr is the resonant frequency, and fn is the normalized frequency. In the embodiment as shown in figure 1 of the drawings,in the embodiment shown in fig. 4, Cp is Cr and Rac is the equivalent load.

The gain curve relative to fn is calculated by the following equation.

In one example, when γ 1 is 0.096 and γ 2 is 0.128, they are plotted as a graph as shown in fig. 6, with the horizontal axis representing the normalized frequency fn and the vertical axis representing the voltage gain. The gain curve in the figure changes from M1 to M7 as Q increases. As can be seen from the figure, the normalized frequency fn range is narrow in the high gain range. For example, the range of operating frequencies within the 5-fold voltage gain range is narrower than the operating frequency within the 4-fold voltage gain range. In one example, if the voltage range is from 40V to 5 times its voltage of 200V, the operating frequency ranges only from 50KHz to less than 200KHz, which is only four times that of 50 KHz. Secondly, the highest frequency is bounded, and when Q is smaller, the voltage gain curves of M1 and M2 substantially coincide, which means that even when tuned to a very deep dimming depth, i.e., Rac → ∞, Q → 0, the operating frequency has the greatest frequency limitation, which can fundamentally solve the problem of the operating frequency range in deep dimming applications of resonant converters. At the same time, the efficiency of the resonant converter is always close to the optimal working point, which means that the technical solution can achieve high efficiency, even when dimming deeply.

As shown in FIGS. 1 and 5, the present application discloses a DC/DC power converter comprising an input switching network 11 for receiving a DC power source and providing an input pulse waveform, a resonant network 12 comprising a resonant capacitor Cs for receiving an output pulse waveform of said input switching network, a first inductor L s connected in series with said resonant capacitor, and a transformer 14 having an excitation inductor L m of less than 10mH connected at one end to said first inductor and at one end to form a loop with said input switching network, wherein said resonant network 12 further comprises a capacitive element such as a capacitor Cr connected in parallel with said excitation inductor L m or in parallel with a secondary side of said transformer 14, and a rectifying circuit 13 connected to a secondary side of said transformer 14 for rectifying an output of said resonant network 12 to power a load, wherein L m is less than 10mH, preferably L m ranges between 1mH and 2mH, the other parts of the DC/DC power converter may be the same as or similar to the aforementioned resonant converter, in the embodiment of FIG. 1, Cr is equivalent to the secondary side of the transformer in parallelIn parallel with the excitation inductance L m of the transformer, in the embodiment shown in fig. 4, Cr is connected on the primary side of the transformer in parallel with the excitation inductance L m.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that many modifications and variations can be made therein. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit and scope of the invention.