阅读说明：本技术 双向scc型llc谐振变换器及其中的电路、控制方法 (Bidirectional SCC type LLC resonant converter, circuit therein and control method ) 是由 岳秀梅 陈鑫跃 莫文慧 李奎 孙仁杰 朱晓楠 张文元 王瀚哲 汪洪亮 于 2019-10-24 设计创作，主要内容包括：本申请公开了一种双向SCC型LLC谐振变换器及其中的电路、控制方法。LLC谐振电路包括：第一电感；第二电感；第二电感的第一端分别与变压器的第一端、第一电感的第一端连接,第二端用于分别与变压器的第二端和逆变/整流桥的第一端连接；电容单元；电容单元的第一端与第一电感的第二端连接,第二端用于与逆变/整流桥的第二端连接；电容单元的电容值可调,在正向以及反向工作时,调节谐振电容值,从而改变电路的特性,例如它的谐振点、品质因数、增益等参数,使得反向工作电路的输入输出的增益在理想的频率带内可以实现大幅度变化,最终得到理想的输出。(The application discloses a bidirectional SCC type LLC resonant converter, a circuit therein and a control method. The LLC resonant circuit includes: a first inductor; a second inductor; the first end of the second inductor is respectively connected with the first end of the transformer and the first end of the first inductor, and the second end of the second inductor is respectively connected with the second end of the transformer and the first end of the inversion/rectification bridge; a capacitor unit; the first end of the capacitor unit is connected with the second end of the first inductor, and the second end of the capacitor unit is used for being connected with the second end of the inverter/rectifier bridge; the capacitance value of the capacitor unit is adjustable, and when the capacitor unit works in the forward direction and the reverse direction, the resonance capacitance value is adjusted, so that the characteristics of the circuit, such as the parameters of a resonance point, a quality factor, gain and the like of the circuit are changed, the gain of the input and output of the reverse working circuit can be greatly changed in an ideal frequency band, and ideal output is finally obtained.)

1. An LLC resonant circuit is characterized by being applied to a bidirectional SCC type LLC resonant converter, wherein the LLC resonant converter at least comprises an inversion/rectification bridge, a transformer and a rectification/inversion bridge, the LLC resonant circuit is respectively connected with the inversion/rectification bridge and the transformer, and the transformer is also connected with the rectification/inversion bridge; the LLC resonant circuit includes:

a first inductor;

a second inductor; the first end of the second inductor is respectively connected with the first end of the transformer and the first end of the first inductor, and the second end of the second inductor is respectively connected with the second end of the transformer and the first end of the inverter/rectifier bridge;

a capacitor unit; the first end of the capacitor unit is connected with the second end of the first inductor, and the second end of the capacitor unit is used for being connected with the second end of the inverter/rectifier bridge;

the capacitance value of the capacitance unit is adjustable, and the capacitance unit is used for generating a required resonance capacitance value when the bidirectional SCC type LLC resonant converter works in the forward direction, so that the input voltage in a first interval is converted into the voltage in a second interval and the voltage is output; and when the bidirectional SCC type LLC resonant converter works in the reverse direction, the resonant capacitance value is adjusted, so that the circuit parameters of the LLC resonant circuit are changed, and the bidirectional SCC type LLC resonant converter converts the input voltage in the second interval into the voltage in the first interval and outputs the voltage.

2. The LLC resonant circuit of claim 1, wherein said capacitive unit comprises: n capacitors connected in parallel; wherein, the value of N is a positive integer;

when the required resonance capacitance value is generated, the capacitance unit is specifically configured to: turning on a required number of the N capacitors; when the resonance capacitance value is adjusted, the capacitance unit is specifically configured to: adjusting the number of capacitors conducted in the N capacitors;

or, when the required resonance capacitance value is generated, the capacitance unit is specifically configured to: conducting the capacitors with the required number in the N capacitors, conducting at least one conducted capacitor according to a preset frequency, and conducting in each period according to the required conducting time; when the resonance capacitance value is adjusted, the capacitance unit is specifically configured to: adjusting the on-time of the at least one capacitor in each cycle.

3. The LLC resonant circuit of claim 2, wherein if N is 2; the capacitance unit includes: a first capacitor, a second capacitor, a first switching transistor and a second switching transistor;

the first end of the first capacitor is connected with the second end of the first inductor, and the second end of the first capacitor is used for being connected with the second end of the inverter/rectifier bridge;

the first end of the second capacitor is connected with the second end of the first capacitor through a first switching transistor, and the second end of the second capacitor is connected with the first end of the first capacitor through a second switching transistor;

when the required number of capacitors in the N capacitors are turned on, the capacitor unit is specifically configured to: turning on the first capacitor and turning off the second capacitor by turning off the first and second switching transistors; when the number of the capacitors conducted in the N capacitors is adjusted, the capacitor unit is specifically configured to: turning on the second capacitor by turning on the first and second switching transistors;

or, when the required number of capacitors in the N capacitors are turned on, at least one capacitor that is turned on according to a preset frequency and is turned on according to a required turn-on time in each period, the capacitor unit is specifically configured to: turning on the first capacitor, turning on the first switching transistor and the second switching transistor according to a preset frequency to enable the second capacitor to be turned on, and turning on the first switching transistor and the second switching transistor according to a required phase angle of the first switching transistor and the second switching transistor in each period to enable the second capacitor to be turned on according to a required turn-on time; when the on-time of the at least one capacitor in each period is adjusted, the capacitor unit is specifically configured to: adjusting a phase angle of the first switching transistor and the second switching transistor to adjust a conduction time of the second capacitor in each cycle.

4. The LLC resonant circuit of claim 2, wherein if N is 2; the capacitance unit includes: a first capacitor, a second capacitor, a first switching transistor and a second switching transistor;

the first end of the first capacitor is connected with the second end of the first inductor, and the second end of the first capacitor is used for being connected with the second end of the inverter/rectifier bridge;

the first end of the second capacitor is connected with the first end of the first capacitor, and the second end of the second capacitor is used for being connected with the third end of the inverter/rectifier bridge through a first switching transistor and connected with the fourth end of the inverter/rectifier bridge through a second switching transistor;

when the required number of capacitors in the N capacitors are turned on, the capacitor unit is specifically configured to: turning on the first capacitor and turning off the second capacitor by turning off the first and second switching transistors; when the number of the capacitors conducted in the N capacitors is adjusted, the capacitor unit is specifically configured to: turning on the second capacitor by turning on the first and second switching transistors;

or, when the required number of capacitors in the N capacitors are turned on, at least one capacitor that is turned on according to a preset frequency and is turned on according to a required turn-on time in each period, the capacitor unit is specifically configured to: turning on the first capacitor, turning on the first switching transistor and the second switching transistor according to a preset frequency to enable the second capacitor to be turned on, and turning on the first switching transistor and the second switching transistor according to a required phase angle of the first switching transistor and the second switching transistor in each period to enable the second capacitor to be turned on according to a required turn-on time; when the on-time of the at least one capacitor in each period is adjusted, the capacitor unit is specifically configured to: adjusting a phase angle of the first switching transistor and the second switching transistor to adjust a conduction time of the second capacitor in each cycle.

5. The LLC resonant circuit of claim 1, wherein said capacitive unit comprises: a first capacitor, a first switching transistor and a second switching transistor;

the first end of the first capacitor is connected with the second end of the first inductor, and the second end of the first capacitor is used for being connected with the second end of the inverter/rectifier bridge; the second end of the first capacitor is also connected with the first end of the first capacitor through the first switching transistor and the second switching transistor in sequence;

when the required resonance capacitance value is generated, the capacitance unit is specifically configured to: the first switching transistor and the second switching transistor are conducted according to a preset frequency and conducted according to the required conducting time in each period; when the resonance capacitance value is adjusted, the capacitance unit is specifically configured to: adjusting the on-time of the first switching transistor and the second switching transistor in each period.

6. A control method of an LLC resonant circuit, characterized in that the LLC resonant circuit is the LLC resonant circuit according to any one of claims 1-5; the control method comprises the following steps:

when the bidirectional SCC type LLC resonant converter works in the forward direction, the capacitor unit generates a required resonant capacitance value, so that the bidirectional SCC type LLC resonant converter converts an input voltage in a first interval into a voltage in a second interval and outputs the voltage;

and when the bidirectional SCC type LLC resonant converter works in the reverse direction, the capacitance unit adjusts the resonant capacitance value, so that circuit parameters of the bidirectional SCC type LLC resonant circuit are changed, and the bidirectional SCC type LLC resonant converter converts the input voltage in the second interval into the voltage in the first interval and outputs the voltage.

7. The control method according to claim 6, wherein if the capacitance unit comprises N capacitors connected in parallel with each other:

the capacitance unit generates a required resonance capacitance value, including: turning on a required number of the N capacitors; the capacitance unit adjusts the resonance capacitance value, including: adjusting the number of capacitors conducted in the N capacitors;

alternatively, the capacitance unit generates a required resonance capacitance value, including: conducting the capacitors with the required number in the N capacitors, conducting at least one conducted capacitor according to a preset frequency, and conducting in each period according to the required conducting time; the capacitance unit adjusts the resonance capacitance value, including: adjusting the on-time of the at least one capacitor in each cycle.

8. The control method of claim 7, wherein if the capacitive unit comprises: a first capacitor, a second capacitor, a first switching transistor, and a second switching transistor:

the turning on of the required number of capacitors of the N capacitors includes: turning on the first capacitor and turning off the second capacitor by turning off the first and second switching transistors; the adjusting the number of the capacitors conducted in the N capacitors includes: causing the second capacitance by turning on the first switching transistor and the second switching transistor;

or, the turning on the capacitors of the N capacitors, which is in a required number, is performed according to a preset frequency for at least one of the turned on capacitors, and the turning on of the capacitors in each period according to a required turn-on time includes: turning on the first capacitor, turning on the first switching transistor and the second switching transistor according to a preset frequency to enable the second capacitor to be turned on, and turning on the first switching transistor and the second switching transistor according to a required phase angle of the first switching transistor and the second switching transistor in each period to enable the second capacitor to be turned on according to a required turn-on time; the adjusting of the conduction time of the at least one capacitor in each period includes: adjusting a phase angle of the first switching transistor and the second switching transistor to adjust a conduction time of the second capacitor in each cycle.

9. The control method of claim 6, wherein if the capacitance unit comprises: a first capacitor, a first switching transistor and a second switching transistor, the capacitor unit generating a desired resonance capacitance value, comprising: the first switching transistor and the second switching transistor are conducted according to a preset frequency and conducted according to the required conducting time in each period; the capacitance unit adjusts the resonance capacitance value, including: adjusting the on-time of the first switching transistor and the second switching transistor in each period.

10. A bidirectional SCC type LLC resonant converter is characterized by comprising an inverter/rectifier bridge, a transformer, a rectifier/inverter bridge and an LLC resonant circuit; the LLC resonant circuit is as claimed in any one of claims 1-5; the LLC resonant circuit is respectively connected with the inverter/rectifier bridge and the transformer; the transformer is also connected with the rectifying/inverting bridge.

Technical Field

The application relates to the technical field of LLC resonant circuits, in particular to a bidirectional SCC type LLC resonant converter, a circuit and a control method thereof.

Background

A Direct current-Direct current (DC/DC) converter is a device that converts electric energy of one voltage value into electric energy of another voltage value in a DC circuit. The fields of large-scale data centers, aerospace systems, new energy power generation, LED lighting, electric vehicle charging and the like all put higher and higher requirements on the capacity, efficiency and power density of the DC/DC converter, and therefore, it is an industrial energy saving and application requirement to develop a DC/DC converter with high efficiency, high power density and high reliability. LLC resonant converters are currently the more common DC/DC converters. On the one hand, the LLC resonant converter realizes a primary side Zero Voltage Switching (ZVS) and a secondary side Zero Current Switching (ZCS), which greatly reduces the element loss and has higher efficiency, on the other hand, because the reduction of loss alleviates the heat dissipation, the Switching frequency can be further improved, the magnetic element volume is further reduced, thereby obtaining high power density performance, therefore, compared with other DC/DC converters, the LLC resonant converter has higher efficiency and higher power density, so that the LLC resonant converter obtains faster development, has wider application prospect, and becomes a mainstream converter in the field of DC/DC converters.

With the development of science and technology, there is an increasing demand for a bidirectional DC/DC converter, which is a DC/DC converter capable of realizing bidirectional flow of energy, and when the converter works in a forward direction, energy can flow from an input end to an output end, and when the converter works in a reverse direction, energy can flow from the output end to the input end.

Disclosure of Invention

The application aims to provide a bidirectional SCC type LLC resonant converter, a circuit and a control method thereof, and aims to solve the problem of poor output quality when energy bidirectional flow is realized based on a traditional LLC resonant circuit in the related art.

The purpose of the application is realized by the following technical scheme:

an LLC resonant circuit is applied to a bidirectional SCC type LLC resonant converter, the LLC resonant converter at least comprises an inversion/rectification bridge, a transformer and a rectification/inversion bridge, the LLC resonant circuit is respectively connected with the inversion/rectification bridge and the transformer, and the transformer is also connected with the rectification/inversion bridge; the LLC resonant circuit includes:

a first inductor;

a second inductor; the first end of the second inductor is respectively connected with the first end of the transformer and the first end of the first inductor, and the second end of the second inductor is respectively connected with the second end of the transformer and the first end of the inverter/rectifier bridge;

a capacitor unit; the first end of the capacitor unit is connected with the second end of the first inductor, and the second end of the capacitor unit is used for being connected with the second end of the inverter/rectifier bridge;

the capacitance value of the capacitance unit is adjustable, and the capacitance unit is used for generating a required resonance capacitance value when the bidirectional SCC type LLC resonant converter works in the forward direction, so that the input voltage in a first interval is converted into the voltage in a second interval and the voltage is output; and when the bidirectional SCC type LLC resonant converter works in the reverse direction, the resonant capacitance value is adjusted, so that the circuit parameters of the LLC resonant circuit are changed, and the bidirectional SCC type LLC resonant converter converts the input voltage in the second interval into the voltage in the first interval and outputs the voltage.

Optionally, the capacitor unit includes: n capacitors connected in parallel; wherein, the value of N is a positive integer;

when the required resonance capacitance value is generated, the capacitance unit is specifically configured to: turning on a required number of the N capacitors; when the resonance capacitance value is adjusted, the capacitance unit is specifically configured to: adjusting the number of capacitors conducted in the N capacitors;

or, when the required resonance capacitance value is generated, the capacitance unit is specifically configured to: conducting the capacitors with the required number in the N capacitors, conducting at least one conducted capacitor according to a preset frequency, and conducting in each period according to the required conducting time; when the resonance capacitance value is adjusted, the capacitance unit is specifically configured to: adjusting the on-time of the at least one capacitor in each cycle.

Optionally, if the value of N is 2; the capacitance unit includes: a first capacitor, a second capacitor, a first switching transistor and a second switching transistor;

the first end of the first capacitor is connected with the second end of the first inductor, and the second end of the first capacitor is used for being connected with the second end of the inverter/rectifier bridge;

the first end of the second capacitor is connected with the second end of the first capacitor through a first switching transistor, and the second end of the second capacitor is connected with the first end of the first capacitor through a second switching transistor;

when the required number of capacitors in the N capacitors are turned on, the capacitor unit is specifically configured to: turning on the first capacitor and turning off the second capacitor by turning off the first and second switching transistors; when the number of the capacitors conducted in the N capacitors is adjusted, the capacitor unit is specifically configured to: turning on the second capacitor by turning on the first and second switching transistors;

or, when the required number of capacitors in the N capacitors are turned on, at least one capacitor that is turned on according to a preset frequency and is turned on according to a required turn-on time in each period, the capacitor unit is specifically configured to: turning on the first capacitor, turning on the first switching transistor and the second switching transistor according to a preset frequency to enable the second capacitor to be turned on, and turning on the first switching transistor and the second switching transistor according to a required phase angle of the first switching transistor and the second switching transistor in each period to enable the second capacitor to be turned on according to a required turn-on time; when the on-time of the at least one capacitor in each period is adjusted, the capacitor unit is specifically configured to: adjusting a phase angle of the first switching transistor and the second switching transistor to adjust a conduction time of the second capacitor in each cycle.

Optionally, if the value of N is 2; the capacitance unit includes: a first capacitor, a second capacitor, a first switching transistor and a second switching transistor;

the first end of the first capacitor is connected with the second end of the first inductor, and the second end of the first capacitor is used for being connected with the second end of the inverter/rectifier bridge;

the first end of the second capacitor is connected with the first end of the first capacitor, and the second end of the second capacitor is used for being connected with the third end of the inverter/rectifier bridge through a first switching transistor and connected with the fourth end of the inverter/rectifier bridge through a second switching transistor;

when the required number of capacitors in the N capacitors are turned on, the capacitor unit is specifically configured to: turning on the first capacitor and turning off the second capacitor by turning off the first and second switching transistors; when the number of the capacitors conducted in the N capacitors is adjusted, the capacitor unit is specifically configured to: turning on the second capacitor by turning on the first and second switching transistors;

or, when the required number of capacitors in the N capacitors are turned on, at least one capacitor that is turned on according to a preset frequency and is turned on according to a required turn-on time in each period, the capacitor unit is specifically configured to: turning on the first capacitor, turning on the first switching transistor and the second switching transistor according to a preset frequency to enable the second capacitor to be turned on, and turning on the first switching transistor and the second switching transistor according to a required phase angle of the first switching transistor and the second switching transistor in each period to enable the second capacitor to be turned on according to a required turn-on time; when the on-time of the at least one capacitor in each period is adjusted, the capacitor unit is specifically configured to: adjusting a phase angle of the first switching transistor and the second switching transistor to adjust a conduction time of the second capacitor in each cycle.

Optionally, the capacitor unit includes: a first capacitor, a first switching transistor and a second switching transistor;

the first end of the first capacitor is connected with the second end of the first inductor, and the second end of the first capacitor is used for being connected with the second end of the inverter/rectifier bridge; the second end of the first capacitor is also connected with the first end of the first capacitor through the first switching transistor and the second switching transistor in sequence;

when the required resonance capacitance value is generated, the capacitance unit is specifically configured to: the first switching transistor and the second switching transistor are conducted according to a preset frequency and conducted according to the required conducting time in each period; when the resonance capacitance value is adjusted, the capacitance unit is specifically configured to: adjusting the on-time of the first switching transistor and the second switching transistor in each period.

A method of controlling an LLC resonant circuit, said LLC resonant circuit being as claimed in any one of the preceding claims; the control method comprises the following steps:

when the bidirectional SCC type LLC resonant converter works in the forward direction, the capacitor unit generates a required resonant capacitance value, so that the bidirectional SCC type LLC resonant converter converts an input voltage in a first interval into a voltage in a second interval and outputs the voltage;

and when the bidirectional SCC type LLC resonant converter works in the reverse direction, the capacitance unit adjusts the resonant capacitance value, so that circuit parameters of the bidirectional SCC type LLC resonant circuit are changed, and the bidirectional SCC type LLC resonant converter converts the input voltage in the second interval into the voltage in the first interval and outputs the voltage.

Optionally, if the capacitance unit includes N capacitors connected in parallel:

the capacitance unit generates a required resonance capacitance value, including: turning on a required number of the N capacitors; the capacitance unit adjusts the resonance capacitance value, including: adjusting the number of capacitors conducted in the N capacitors;

alternatively, the capacitance unit generates a required resonance capacitance value, including: conducting the capacitors with the required number in the N capacitors, conducting at least one conducted capacitor according to a preset frequency, and conducting in each period according to the required conducting time; the capacitance unit adjusts the resonance capacitance value, including: adjusting the on-time of the at least one capacitor in each cycle.

Optionally, if the capacitor unit includes: a first capacitor, a second capacitor, a first switching transistor, and a second switching transistor:

the turning on of the required number of capacitors of the N capacitors includes: turning on the first capacitor and turning off the second capacitor by turning off the first and second switching transistors; the adjusting the number of the capacitors conducted in the N capacitors includes: causing the second capacitance by turning on the first switching transistor and the second switching transistor;

or, the turning on the capacitors of the N capacitors, which is in a required number, is performed according to a preset frequency for at least one of the turned on capacitors, and the turning on of the capacitors in each period according to a required turn-on time includes: turning on the first capacitor, turning on the first switching transistor and the second switching transistor according to a preset frequency to enable the second capacitor to be turned on, and turning on the first switching transistor and the second switching transistor according to a required phase angle of the first switching transistor and the second switching transistor in each period to enable the second capacitor to be turned on according to a required turn-on time; the adjusting of the conduction time of the at least one capacitor in each period includes: adjusting a phase angle of the first switching transistor and the second switching transistor to adjust a conduction time of the second capacitor in each cycle.

Optionally, if the capacitor unit includes: a first capacitor, a first switching transistor and a second switching transistor, the capacitor unit generating a desired resonance capacitance value, comprising: the first switching transistor and the second switching transistor are conducted according to a preset frequency and conducted according to the required conducting time in each period; the capacitance unit adjusts the resonance capacitance value, including: adjusting the on-time of the first switching transistor and the second switching transistor in each period.

A bidirectional SCC type LLC resonant converter comprises an inverter/rectifier bridge, a transformer, a rectifier/inverter bridge and an LLC resonant circuit; wherein the LLC resonant circuit is the LLC resonant circuit of any one of the above; the LLC resonant circuit is respectively connected with the inverter/rectifier bridge and the transformer; the transformer is also connected with the rectifying/inverting bridge.

This application adopts above technical scheme, has following beneficial effect:

the LLC resonant circuit provided by the scheme of the application comprises a basic first inductor, a basic second inductor and a basic capacitor unit, wherein, the capacitance value of the capacitance unit is adjustable, and when the capacitance unit is applied to the bidirectional SCC type LLC resonant converter, when the capacitor unit works in the positive direction, the capacitor unit can generate the required resonance capacitance value at the moment, the requirement of wide voltage input and output is met, in the reverse operation, when the input/output condition can not reach the target requirement, compared with the related art, the internal circuit parameters of the LLC resonant circuit can be changed, i.e. the capacitance value of the capacitive element, and thus the characteristics of the circuit, such as its resonance point, quality factor, gain etc. parameters, the gain of the input and output of the reverse working circuit can be greatly changed in an ideal frequency band, and finally an ideal output is obtained, therefore, the output quality of the bidirectional SCC type LLC resonant converter during bidirectional flow is improved.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a structural diagram of an LLC resonant circuit provided in an embodiment of the present application.

Fig. 2 is a graph of frequency versus gain curves of a conventional LLC resonant circuit provided in an embodiment of the present application.

Fig. 3 is a schematic diagram of an LLC resonant circuit according to an embodiment of the present application.

Fig. 4 is a schematic waveform diagram of a capacitor unit according to an embodiment of the present application.

Fig. 5 is a schematic diagram of a first operation mode of a capacitor unit according to an embodiment of the present application.

Fig. 6 is a schematic diagram of a second operation mode of a capacitor unit according to an embodiment of the present application.

Fig. 7 is a schematic diagram of a third operation mode of a capacitor unit according to an embodiment of the present application.

Fig. 8 is a schematic diagram of an LLC resonant circuit according to another embodiment of the present application.

Fig. 9 is a schematic diagram of an LLC resonant circuit according to another embodiment of the present application.

Fig. 10 is a flowchart of a control method of an LLC resonant circuit according to an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be described in detail below. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without making any creative effort, shall fall within the protection scope of the present application.