WO2023082810A1

WO2023082810A1 - Dc-dc voltage conversion apparatus, power supply device, and control method for dc-dc voltage conversion apparatus

Info

Publication number: WO2023082810A1
Application number: PCT/CN2022/117511
Authority: WO
Inventors: 陈建; 刘源俊; 胡志祥; 王帅兵
Original assignee: 华为数字能源技术有限公司
Priority date: 2021-11-10
Filing date: 2022-09-07
Publication date: 2023-05-19
Also published as: CN114499196A

Abstract

A DC-DC voltage conversion apparatus, a power supply device, and a control method for a DC-DC voltage conversion apparatus. The dynamic response speed of a DC-DC voltage conversion apparatus can be increased. The apparatus comprises a resonant conversion unit, a resonant signal sampling unit, an output voltage sampling unit and a controller. The resonant signal sampling unit is used for sampling a resonant voltage vcr at a primary side of a transformer in the resonant conversion unit, and outputting a sampling reference voltage vsns; the output voltage sampling unit is used for sampling an output voltage Vout of the resonant conversion unit, and outputting a feedback voltage Vfb; and the controller is further used for: acquiring the sampling reference voltage vsns and the feedback voltage Vfb; and obtaining a time length parameter tlp according to the feedback voltage Vfb; and outputting a switch control signal for controlling the switching-on/switching-off of a switch S1 and a switch S2, wherein the switch control signal is determined according to the time length parameter Tlp and the sampling reference voltage vsns.

Description

A DC-DC voltage conversion device, power supply equipment and control method

This application claims the priority of the Chinese patent application with the application number 202111327802.X and the application name "A DC-DC voltage conversion device, power supply equipment and control method" submitted to the China Patent Office on November 10, 2021. The entire contents are incorporated by reference in this application.

technical field

The present application relates to the field of circuits, and more specifically, to a DC-DC voltage conversion device, a power supply device and a control method.

Background technique

In the field of power supply, such as personal computer (personal computer, PC) machine power supply, communication power supply, industrial power supply and other fields, switching converters, such as direct current to direct current (DC-DC) voltage converters, are used. In order to improve the efficiency of the switching converter, it is necessary to realize the soft switching of the device. Among them, the resonant soft-switching topology uses a resonant element to make the current lag the voltage to achieve soft-switching control. For example, the resonant soft-switching topology usually chops the DC input to obtain a high-frequency square wave, then realizes voltage regulation and soft switching through a resonant cavity and a transformer, and finally obtains the required DC output through rectification and filtering.

Wherein, the resonant switching circuit is usually controlled by pulse frequency modulation (PFM), and the PFM control usually adopts a voltage control mode. In one cycle, the input and output voltage gain of the resonant cavity is changed by adjusting the switching frequency fs to realize the adjustment of the output voltage. The control of the PFM is regulated by sampling the output voltage feedback. If the output voltage is lower than the reference voltage, reduce the switching frequency fs to increase the voltage gain; if the output voltage is greater than the reference voltage, increase the switching frequency fs. When the switching frequency reaches the maximum frequency limit, the resonant circuit enters a burst mode. In the burst mode, the circuit can stop for a period of time every time it works to reduce the output power.

In the PFM control mode, the resonant switching circuit has the problem of slow dynamic response from light-load mode to heavy-load mode, and the switching point of entering light-load mode is determined according to the switching frequency fs, not according to the load. Therefore, The fluctuation of the parameters of the resonant component will cause the load point to enter the light-load mode to change significantly, resulting in inaccurate control of the load point when the light-load mode is switched.

Contents of the invention

The present application provides a DC-DC voltage conversion device, power supply equipment and control method, which can improve the dynamic response speed of the DC-DC voltage conversion device, and more accurately configure the load point for light-load mode and heavy-load mode conversion, improving the Control efficiency of DC-DC voltage conversion device.

In a first aspect, a DC-DC voltage conversion device is provided, including: a resonant conversion unit, including a high-frequency chopper circuit, a resonant cavity, a transformer, and a rectification and filtering network, and the high-frequency chopper circuit includes switches S1 and S2; a controller, configured to convert the DC voltage V _in input into the high-frequency chopper circuit into a high-frequency square wave by controlling the on-off of the switches S1 and S2, and the resonant cavity and the transformer are used to receive the The high-frequency square wave is used to couple the electric energy from the primary side of the transformer to the secondary side, and the rectification and filtering network is used to convert the AC voltage coupled to the secondary side of the transformer into a DC voltage and output it as Voltage V _out ; a resonant signal sampling unit, used to sample the resonant voltage v _cr on the primary side of the transformer, and output a sampled reference voltage v _sns , the sampled reference voltage v _sns is used to reflect the resonant voltage v _cr on the primary side of the transformer. The change of the resonance current i _cr ; the output voltage sampling unit is used to sample the output voltage V _out of the resonant conversion unit, and output the feedback voltage V _fb ; the controller is also used to: obtain the sampling reference voltage v _sns and the Feedback voltage V _fb ; obtain a time length parameter t _lp according to the feedback voltage V _fb ; output a switch control signal for controlling the on-off of the switch S1 and the switch S2, and the switch control signal is based on the time length parameters t _lp and the sampling reference voltage v _sns are determined.

This scheme introduces a comprehensive sampling circuit of resonant current i _cr and resonant voltage v _cr , that is, the sampling reference voltage v _sns can reflect the changes of resonant voltage v _cr and resonant current i _cr at the same time, so by using the sampling reference voltage v _sns and the time length parameters t _lp controls the switching on and off of the switch in the DC-DC voltage conversion device, which can realize fast loop control, thereby obtaining faster dynamic response speed. In addition, by adjusting the resistance-capacitance parameters in the resonant signal sampling unit, the zero-crossing time of no-load and full-load can also be configured, so as to realize the accurate configuration of the control point of the no-load and full-load load point, and it is easier to realize the entry and exit point of the light-load mode adjustment, thereby improving the control efficiency.

With reference to the first aspect, in a possible implementation manner, the controller is specifically configured to: start a first timing at the first moment t1 when the reference voltage V _sns crosses zero from a negative value; After the timing reaches the second moment t2 of the time length parameter _tlp , control the switch S1 to be in an off state, and then control the switch S2 to be in a conduction state; when the reference voltage V _sns crosses zero from a positive value After the third moment t3, start the second timing; after the second timing reaches the fourth moment t4 of the time length parameter _tlp , control the switch S2 to be in the off state, and then control the switch S1 to be in the conduction state. pass status.

The sampling reference voltage v _sns can reflect the change of the resonant voltage v _cr and the resonant current i _cr at the same time, by monitoring the zero-crossing time of the sampling reference voltage v _sns within one clock cycle of switches S1 and S2, and using the time length parameter t _lp Controlling the time from the zero-crossing point of the sampling reference voltage v _sns to the switch off can realize fast loop control, thereby obtaining faster dynamic response speed.

With reference to the first aspect, in a possible implementation manner, the controller is specifically configured to: calculate and process the feedback voltage V _fb to obtain a proportional coefficient k _lp ; according to the formula

Obtain the time length parameter t _lp , where,

Indicates the average period of the last N switching periods of the switch S1 or the switch S2, where N is an integer greater than 1.

Thus, by calculating the average period of switch S1 (or switch S2) for the previous N periods

make

In this way, the calculation of t _lp is also related to the previous N cycles, which slows down the change of t _lp . Even though the V _fb sampling signal changes quickly, it can also make the loop more stable, thereby optimizing the work of the DC-DC voltage conversion device performance.

With reference to the first aspect, in a possible implementation manner, the time length parameter t _lp meets at least one of the following conditions: there is a negative correlation between the time length parameter t _lp and the output voltage V _out ; the There is a negative correlation between the time length parameter t _lp and the magnitude of the load current.

With reference to the first aspect, in a possible implementation manner, the resonance signal sampling unit includes: a first sampling capacitor C _S1 , a second sampling capacitor C _S2 , and a sampling resistor Rs, and the first sampling capacitor C _S1 One end is used to receive the resonant voltage V _cr on the primary side of the transformer, the second end of the first sampling capacitor C _S1 is used to output the sampling reference voltage V _sns , the second end of the first sampling capacitor C _S1 is connected to The sampling resistor Rs and the second sampling capacitor C _S2 are connected in parallel between ground.

In this scheme, a comprehensive sampling circuit of resonant current i _cr and resonant voltage v _cr is introduced. Wherein, the sampling resistor Rs can be used for sampling the resonant current i _cr , and the second sampling capacitor C _S2 can be used for sampling the resonant voltage v _cr . By adjusting the values of Rs and _CS2 , the sampling ratio of resonant current i _cr and resonant voltage v _cr can be adjusted, so that the time length parameter t _lp can be set within a reasonable range to achieve the purpose of easy detection. Moreover, by adjusting the values of Rs and _CS2 , the zero-crossing time of different loads can be configured, the control of the load point is accurate, and it is easy to adjust the entry and exit points of the light-load mode, thereby improving the control efficiency.

In a second aspect, a control method for a DC-DC voltage conversion device is provided, the DC-DC voltage conversion device includes: a resonant conversion unit, including a high-frequency chopper circuit, a resonant cavity, a transformer, and a rectification and filtering network, the The high-frequency chopper circuit includes switches S1 and S2; the controller is used to convert the DC voltage _Vin input to the high-frequency chopper circuit into a high-frequency square wave by controlling the on-off of the switches S1 and S2, so The resonant cavity and the transformer are used to receive the high-frequency square wave and couple the electric energy from the primary side of the transformer to the secondary side, and the rectification and filtering network is used to couple the electric energy to the secondary side of the transformer The AC voltage is converted into a DC voltage and used as the output voltage V _out ; the resonant signal sampling unit is used to sample the resonant voltage v _cr on the primary side of the transformer, and output the sampling reference voltage v _sns , and the sampling reference voltage v _{sns is} used To reflect changes in the resonant voltage v _cr and resonant current i _cr on the primary side of the transformer; the output voltage sampling unit is used to sample the output voltage V _out of the resonant conversion unit and output the feedback voltage V _fb ; the method includes: the control The controller obtains the sampling reference voltage v _sns and the feedback voltage V _fb ; the controller obtains the time length parameter t _lp according to the feedback voltage V _fb ; the output of the controller is used to control the switch S1 and the A switch control signal for switching on and off the switch S2, the switch control signal is determined according to the time length parameter t _lp and the sampling reference voltage v _sns

With reference to the second aspect, in a possible implementation manner, the controller outputs a switch control signal for controlling the switching of the switch S1 and the switch S2, including: the controller is at the reference voltage v _sns starts the first timing from the first moment t1 when the negative value crosses zero; the controller controls the switch S1 to be turned off after the first timing reaches the second moment t2 of the time length parameter _tlp state, and then control the switch S2 to be in the conduction state; the controller starts the second timing after the third moment t3 when the reference voltage v _sns crosses zero from a positive value; the controller starts the second timing in the second After timing reaches the fourth moment t4 of the time length parameter _tlp , control the switch S2 to be in the off state, and then control the switch S1 to be in the on state.

With reference to the second aspect, in a possible implementation manner, the controller performs calculation processing on the feedback voltage V _fb to obtain a time length parameter t _lp , including: performing calculation processing on the feedback voltage V _fb to obtain Proportionality factor k _lp ; according to the formula

Obtain the time length parameter t _lp , where,

With reference to the second aspect, in a possible implementation manner, the time length parameter t _lp meets at least one of the following conditions: there is a negative correlation between the time length parameter t _lp and the output voltage V _out ; the There is a negative correlation between the time length parameter t _lp and the magnitude of the load current.

With reference to the second aspect, in a possible implementation manner, the resonance signal sampling unit includes: a first sampling capacitor C _S1 , a second sampling capacitor C _S2 , and a sampling resistor Rs, and the first sampling capacitor C _S1 One end is used to receive the resonant voltage V _cr on the primary side of the transformer, the second end of the first sampling capacitor C _S1 is used to output the sampling reference voltage V _sns , the second end of the first sampling capacitor C _S1 is connected to The sampling resistor Rs and the second sampling capacitor C _S2 are connected in parallel between ground.

In a third aspect, an electronic device is provided, and the electronic device is provided with the DC-DC voltage conversion device as described in the first aspect or any possible implementation manner of the first aspect.

In a fourth aspect, there is provided a computer-readable storage medium for storing a computer program, and the computer program includes a method for executing the above-mentioned second aspect or any possible implementation manner of the second aspect.

In a fifth aspect, a computer program product is provided, including a computer program, where the computer program includes instructions for executing the method in the above-mentioned second aspect or any possible implementation manner of the second aspect.

According to a sixth aspect, a control chip is provided, and the control chip is provided with a circuit for performing the method in the above second aspect or any possible implementation manner of the second aspect.

In a seventh aspect, a power supply device is provided, the power supply device is used to supply power to a load, and the power supply device includes: an AC-DC (alternating current to direct current, AC-DC) voltage conversion unit for converting an AC voltage into a DC Voltage: the DC-DC voltage conversion device described in the first aspect or any possible manner of the first aspect, configured to receive the DC voltage output by the AC-DC voltage conversion unit and perform DC voltage conversion.

Description of drawings

FIG. 1 is a schematic diagram of the principle of a DC-DC resonant converter according to an embodiment of the present application.

FIG. 2 is a schematic topology diagram of a half-bridge LLC resonant converter 100 according to an embodiment of the present application.

FIG. 3 is a schematic structural diagram of a DC-DC voltage conversion device 300 according to an embodiment of the present application.

FIG. 4 is a schematic diagram of working waveforms of the controller 320 according to an embodiment of the present application.

FIG. 5 is a schematic circuit diagram of an output voltage sampling unit 340 according to an embodiment of the present application.

FIG. 6 is a circuit structure diagram of a resonance signal sampling unit 330 according to an embodiment of the present application.

FIG. 7 is a schematic diagram of a circuit analysis of the resonance signal sampling unit 330 in FIG. 6 .

FIG. 8 is a schematic diagram of another circuit analysis of the resonance signal sampling unit 330 in FIG. 6 .

FIG. 9 is a schematic diagram of working waveforms of the resonance signal sampling unit 330 in FIG. 6 .

FIG. 10 is a schematic structural diagram of a DC-DC voltage conversion device 400 according to another embodiment of the present application.

FIG. 11 is a schematic circuit diagram of a zero-crossing comparison unit 350 according to an embodiment of the present application.

FIG. 12 is a schematic diagram of working waveforms of the zero-crossing comparison unit 350 according to an embodiment of the present application.

FIG. 13 is a functional schematic diagram of a control method implemented by the controller 320 according to an embodiment of the present application.

FIG. 14 is a working waveform diagram of the controller 320 according to an embodiment of the present application.

Fig. 15 shows a working waveform diagram of a DC-DC voltage conversion device working in a light load mode according to an embodiment of the present application.

Fig. 16 shows a working waveform diagram of a DC-DC voltage converting device working in a heavy load mode according to an embodiment of the present application.

Fig. 17 shows a working waveform diagram of a DC-DC voltage conversion device in a light load mode according to another embodiment of the present application.

Fig. 18 shows a working waveform diagram of a DC-DC voltage conversion device in another embodiment of the present application working in a heavy load mode.

FIG. 19 is a functional schematic diagram of a control method implemented by the controller 320 according to another embodiment of the present application.

FIG. 20 is a working waveform diagram corresponding to the control method shown in FIG. 19 .

Detailed ways

The technical solution in this application will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of the principle of a DC-DC resonant converter according to an embodiment of the present application. As shown in Figure 1, the resonant converter obtains a high-frequency square wave after the DC input voltage is subjected to high-frequency chopping, and then realizes voltage regulation and soft switching through a resonant cavity and a transformer, and finally obtains a DC output voltage through rectification and filtering.

Wherein, if the high-frequency chopping part adopts a half-bridge circuit, the resonant cavity adopts an LLC type, and the rectification adopts a diode full-wave rectification, then a half-bridge LLC resonant converter topology 100 as shown in FIG. 2 is obtained.

FIG. 2 is a schematic topology diagram of a half-bridge LLC resonant converter 100 according to an embodiment of the present application. As shown in FIG. 2 , the resonant converter 100 includes a high frequency chopper circuit 101 , a resonant cavity 102 , a transformer 103 and a rectifying and filtering network 104 . Wherein, the high frequency chopper circuit 101 includes an input filter capacitor C _I , switches S1 and S2 . Wherein, the diodes connected to the switches S1 and S2 shown in FIG. 2 are their body diodes, and the capacitors connected to them are their parasitic capacitances. The resonant cavity 102 includes a resonant inductance Lr and a resonant capacitor Cr. The resonant inductance Lr includes the leakage inductance of the transformer 103 and an external inductance, and can also be fully integrated in the transformer 103 . The transformer 103 may be a transformer Tr, whose primary-side excitation inductance is denoted as Lm; the rectification and filtering network 104 includes diodes D1 and D2, and an output filter capacitor C _O .

The first terminal of the switch S1 is connected to the positive pole of the input voltage, the second terminal of the switch S1 is connected to the first terminal of the switch S2, and the second terminal of the switch S2 is connected to the negative pole of the input terminal. The switch S1 is also called an upper drive tube or an upper tube, and the switch S2 is also called a lower drive tube or a lower tube. It should be understood that, for ease of description, the first end and the second end of the switch in the embodiment of the present application may refer to the source and the drain of the transistor respectively. In addition, the gate of the transistor can be used to receive the control signal of the switch.

In some examples, the switches S1 and S2 may be made of silicon carbide (silicon carbide, SiC) or gallium nitride (gallium nitride, GaN) and other materials using silicon semiconductor materials (silicon, Si) or third-generation wide bandgap semiconductor materials. Made of field-effect transistors (field-effect transistor, FET).

Half-bridge LLC usually adopts PFM control mode. In one cycle, ignoring the dead time, S1 and S2 are each turned on for 50% of the time. By adjusting the switching frequency fs, the input and output voltage gain of the resonant cavity is changed to realize the adjustment of the output voltage.

The embodiment of the present application proposes a DC-DC voltage conversion device and a control method, which can improve the dynamic response speed of the DC-DC voltage conversion device by introducing a comprehensive sampling circuit of the resonant current i _cr and the resonant voltage v _cr to control the resonant soft switch , and more precisely configure the load point for light-load mode and heavy-load mode transitions.

Optionally, the DC-DC voltage conversion device in the embodiment of the present application can be used in a power supply device, and the power supply device can supply power to a load. The above-mentioned loads may include but not limited to personal computers, mobile phones, computers, TV screens and the like. The power supply equipment may be a DC-DC conversion system, an AC-DC conversion system, or other types of voltage conversion systems. As an example, the power supply equipment may include an AC-DC conversion unit and the DC-DC voltage conversion device in the embodiment of the present application. The AC-DC conversion unit is used to convert the AC voltage into a DC voltage and output it to the DC-DC voltage conversion device.

FIG. 3 is a schematic structural diagram of a DC-DC voltage conversion device 300 according to an embodiment of the present application. As shown in FIG. 3 , the DC-DC voltage conversion device 300 includes a resonance conversion unit 310 , a controller 320 , a resonance signal sampling unit 330 and an output voltage sampling unit 340 . Wherein, the working principle of the resonant conversion unit 310 is similar to the resonant converter described in FIG. 1 and FIG. 2 , and will not be repeated here.

The resonant transformation unit 310 includes a high frequency chopper circuit 311 , a resonant cavity 312 , a transformer 313 and a rectification and filtering network 314 . The high frequency chopper circuit 311 includes switches S1 and S2. The controller 320 converts the DC voltage V _in input into the high-frequency chopper circuit 311 into a high-frequency square wave by controlling the on-off of the switches S1 and S2, and the resonant cavity 312 and the transformer 313 are used to receive the high-frequency square wave and convert the electric energy Coupling from the primary side of the transformer 313 to the secondary side, the rectification and filtering network 314 is used to convert the AC voltage coupled to the secondary side of the transformer 313 into a DC voltage, and output it as the output voltage V _out .

The resonant signal sampling unit 330 is used for sampling _the resonant voltage V _cr at the primary side of the transformer, and outputting the sampling reference voltage v _sns , which is used to reflect the changes of the resonant voltage v _cr and the resonant current i _cr at the primary side of the transformer.

The output voltage sampling unit 340 is used for sampling the output voltage V _out of the resonant conversion unit 310 and outputting a feedback voltage V _fb .

The controller 320 is also used to: acquire the sampling reference voltage v _sns and the feedback voltage V _fb ; obtain the time length parameter t _lp according to the feedback voltage V _fb ; output the switch control signal for controlling the switch S1 and the switch S2 on and off, the switch control signal It is determined according to the time length parameter t _lp and the sampling reference voltage V _sns . In other words, the controller 320 can determine the on-off frequency fs of the switch S1 or the switch S2 according to the time length parameter t _lp and the sampling reference voltage v _sns .

It can be understood that in the loop control, the time length parameter t _lp can be used as the zero-crossing time of the sampling reference voltage v _sns to control the switching cycle of the switch S1 or the switch S2, and the specific scheme is as follows.

In some examples, in terms of determining the on-off frequency fs of the switch S1 or the switch S2 according to the time length parameter t _lp and the reference sampling voltage v _sns , the controller 320 is specifically configured to: when the reference voltage v _sns rises from a negative value At the first moment t1 when it reaches zero, start the first timing; at the second moment t2 when the first timing reaches the time length parameter _tlp , switch S1 is turned off, and then switch S2 is turned on. And, at the third moment t3 when the reference voltage V _sns drops from a positive value to zero, start the second timing; at the fourth moment t4 when the second timing reaches the time length parameter _tlp , turn off the switch S2, and then turn on the switch S1 .

FIG. 4 is a schematic diagram of working waveforms of the controller 320 according to an embodiment of the present application. As shown in FIG. 4 , in some examples, the control logic of the controller 320 is as follows: In a switching cycle, first, assume that the moment when the switch S1 is turned on is the initial time t0 of a cycle, and the V _sns signal is negative at this time value. The moment when the v _sns signal crosses zero from the negative value is the first moment t1. At this time, the timer starts counting. When the time counted by the timer reaches _tlp , it is the second moment t2. At this time, the switch S1 is turned off. Clear the timer, then enter the dead time, and wait for the soft-open condition of switch S2 to be realized. After the soft-open condition of switch S2 is met or the fixed dead time is over, switch S2 is turned on, and the V _sns signal is positive at this time. The moment when the v _sns signal crosses zero from the positive value is the third moment t3. At this time, the timer starts counting again. When the time counted by the timer reaches t _lp , it is the moment t4. At this time, the switch S2 is turned off and enters the dead zone, waiting Switch S1 is turned on again. So far, the control process of one switching cycle ends.

Optionally, the controller 320 may perform calculation processing on the feedback voltage V _fb to obtain the time length parameter t _lp . Specifically, the time length parameter t _lp meets at least one of the following conditions: there is a negative correlation between the time length parameter t _lp and the output voltage V _out . There is a negative correlation between the time length parameter t _lp and the magnitude of the load current. In other words, there is a positive correlation between the time length parameter t _lp and the size of the load.

It should be noted that the above-mentioned negative correlation between the time length parameter t _lp and the output voltage V _out and the load current may be linear or non-linear.

In some examples, the controller 320 may perform loop calculation according to the feedback voltage V _fb to directly obtain the time length parameter t _lp .

In some examples, controller 320 may obtain a scaling factor k _lp . And according to the proportional coefficient k _lp and the average cycle of the last N switching cycles, the time length parameter t _lp is obtained. For example, the controller 320 is specifically configured to: calculate and process the feedback voltage V _fb to obtain the proportional coefficient k _lp ; according to the formula

Get the time length parameter t _lp , where,

Indicates the average period of the last N switching cycles of switches S1 and S2.

In terms of logic control, because the V _fb signal is sufficient to feed back the change of the output load, if t _lp is still used to control the switching cycle, t _lp changes quickly, and t _lp is also affected by the output voltage V _out , which may cause loop instability Stablize. Thus, by calculating the average period of switch S1 (or switch S2) for the previous N periods

make

FIG. 5 is a schematic circuit diagram of an output voltage sampling unit 340 according to an embodiment of the present application. As shown in FIG. 5 , the input terminal of the output sampling circuit unit 340 is used for connecting the output voltage V _out , and the output terminal is used for outputting the feedback voltage V _fb .

The output sampling circuit unit 340 includes resistors R1 - R4 , a capacitor C1 , a controllable voltage regulator TL, and an optocoupler opt.

Wherein, the resistors R1 and R2 are used to divide the input voltage (ie, V _out ), and the controllable voltage regulator TL is used to convert the input voltage into a current for driving the optocoupler device opt. The capacitor C1 and the resistor R4 form a compensation circuit of the loop. The optocoupler device opt refers to a device that transmits electrical signals through light as a medium, and is used to realize sampling isolation between the primary side and the secondary side of the transformer.

It should be understood that FIG. 5 is only used as an example of the output voltage sampling unit 340 , rather than limitation, and the output voltage sampling unit 340 may also be implemented using other circuit topologies.

FIG. 6 is a circuit structure diagram of a resonance signal sampling unit 330 according to an embodiment of the present application. As shown in FIG. 6 , the resonance signal sampling unit 330 includes: a first sampling capacitor C _S1 , a second sampling capacitor _CS2 , and a sampling resistor Rs. The first end of the first sampling capacitor _CS1 is used to receive the resonance voltage on the primary side of the transformer. V _cr , the second terminal of the first sampling capacitor C _S1 is used to output the sampling reference voltage v _sns , and a sampling resistor Rs and a second sampling capacitor C _S2 are connected in parallel between the second terminal of the first sampling capacitor C _S1 and ground.

It should be understood that FIG. 6 is only used as an example of the resonance signal sampling unit 330 and is not limited thereto, and the resonance signal sampling unit 330 may also be implemented using other circuit topologies.

FIG. 7 is a schematic diagram of a circuit analysis of the resonance signal sampling unit 330 in FIG. 6 . As shown in FIG. 7 , if the second sampling capacitor C _S2 is ignored, the first sampling capacitor C _S1 and the sampling resistor Rs form a sampling circuit for the resonant current i _cr . The sampling reference voltage v _sns can be expressed by the following formula (1):

Among them, Cr represents the resonant capacitance.

FIG. 8 is a schematic diagram of another circuit analysis of the resonance signal sampling unit 330 in FIG. 6 . As shown in FIG. 8, if the sampling resistor Rs is ignored, the first sampling capacitor _CS1 and the second sampling capacitor _CS2 form a sampling circuit for the resonant voltage _vcr . The sampling reference voltage v _sns can be expressed by the following formula (2):

FIG. 9 is a schematic diagram of working waveforms of the resonance signal sampling unit 330 in FIG. 6 . As shown in Figure 9, the sampling resistor Rs, the first sampling capacitor C _S1 and the second sampling capacitor C _S2 combine the sampling of the resonant current i _cr and the resonant voltage v _cr , assuming that the first sampling capacitor C _S1 is fixed , if the sampling resistor Rs takes a larger value, the sampling of the resonant current i _cr dominates the final sampling signal; if the second sampling capacitor _CS2 takes a larger value, the sampling of the resonant voltage i _cr dominates the final sampling signal, so it can be By adjusting the parameters of the resistance and capacitance, the waveform v _sns of the resonant signal sampling output is adjusted.

Optionally, by adjusting the parameters of the sampling resistor Rs or the second sampling capacitor _CS2 in the resonance signal sampling unit 330, the sampling ratio of the feedback resonance voltage v _cr and resonance current i _cr in the sampling reference voltage v _sns can be changed.

In the embodiment of the present application, a comprehensive sampling circuit of the resonant current i _cr and the resonant voltage v _cr is introduced. Wherein, the sampling resistor Rs can be used for sampling the resonant current i _cr , and the second sampling capacitor C _S2 can be used for sampling the resonant voltage v _cr . By adjusting the values of Rs and _CS2 , the sampling ratio of the resonant current i _cr and the resonant voltage v _cr can be adjusted, and the time between the zero-crossing time of different loads and the switching on and off of the switch can be adjusted. Therefore, by adjusting the values of Rs and _CS2 , the control points of the no-load and full-load load points are now accurately configured, and the adjustment of the entry and exit points of the light-load mode is more easily realized, thereby improving the control efficiency.

FIG. 10 is a schematic structural diagram of a DC-DC voltage conversion device 400 according to another embodiment of the present application. The difference from the DC-DC voltage conversion device 300 in FIG. 3 is that the DC-DC voltage conversion device 400 further includes a zero-crossing comparison unit 350 . The zero-crossing comparison unit 350 is configured to receive the sampling reference signal v _sns , compare v _sns with the threshold voltage Vth, and then output a comparison result signal cmp to the controller 320 . Wherein, the threshold voltage Vth may be zero level. That is, the zero-crossing comparison unit 350 is used to output the comparison result cmp between vs _sns and zero level. The controller 320 can output switch control signals p1 and p2 according to the comparison result cmp.

It should be understood that the controller 320 in FIG. 3 can also implement the function of the zero-crossing comparison unit 350 , that is, the zero-crossing comparison unit 350 can be integrated in the controller 320 or can be independent from the controller 320 .

FIG. 11 is a schematic circuit diagram of a zero-crossing comparison unit 350 according to an embodiment of the present application. As shown in FIG. 11 , the zero-cross comparison unit 350 includes a comparator CMP1 . One input terminal of the comparator CMP1 is used for connecting the threshold voltage Vth, and the other input terminal of the comparator CMP1 is used for receiving the sampling reference voltage v _sns . The comparator CMP1 is used to compare the sampling reference voltage v _sns with the threshold voltage Vth, and output the comparison result cmp.

FIG. 12 is a schematic diagram of working waveforms of the zero-crossing comparison unit 350 according to an embodiment of the present application. As shown in FIG. 12 , when the sampling reference voltage v _sns is greater than the threshold voltage Vth, the comparator CMP1 outputs a high voltage (or logic 1). When the sampling reference voltage v _sns is lower than the threshold voltage Vth, the comparator CMP1 outputs a low voltage (or logic 0). Wherein, the above-mentioned threshold voltage Vth may be zero level. That is, when the sampling reference voltage V _sns is greater than zero, the comparator CMP1 outputs logic 1; when the sampling reference voltage V _sns is less than zero, the comparator CMP1 outputs logic 0.

FIG. 13 is a functional schematic diagram of a control method implemented by the controller 320 according to an embodiment of the present application. As shown in FIG. 13 , the controller 320 may include a loop calculation unit, a PWM control unit, a time counting unit, and a driving unit. Wherein, the loop calculation unit is used to acquire the feedback voltage V _fb and perform loop control according to the feedback voltage V _fb . Specifically, the loop calculating unit generates a time length parameter t _lp according to the feedback voltage V _fb . The PWM control unit generates control signals pwm1 and pwm2 according to the time length parameter _tlp , and the drive unit is used to convert pwm1 and pwm2 into switch control signals p1 and p2 that directly drive switches S1 and S2, and output the switch control signals to switches S1 and S2.

There is a negative correlation between the time length parameter t _lp and the output voltage V _out . When the output voltage V _out increases, the time length parameter t _lp decreases; when the output voltage V _out decreases, the time length parameter t _lp increases. Wherein, when the time length parameter t _lp is reduced, it is equivalent to increasing the on-off frequency fs of the switches S1 and S2, so that the voltage gain of the resonant conversion unit 310 is reduced, thereby reducing the output voltage V _out to realize the closed-loop control of the LLC loop .

In addition, the function of the time counting unit is equivalent to the timer in the foregoing, which is used to count time according to the comparison result output by the zero-crossing comparison unit 350, and send the timing length tc to the PWM control unit, so that the PWM control unit can calculate the time according to the timing length. tc and the time length parameter t _lp generate control signals pwm1 and pwm2.

FIG. 14 is a working waveform diagram of the controller 320 according to an embodiment of the present application. Among them, V _SW represents the voltage of the midpoint of the bridge arm, and the voltage of the midpoint of the bridge arm V _SW is the voltage of the midpoint of the bridge arm connected to the switches S1 and S2. zone time. As shown in FIG. 14 , at time t0 , the controller 320 controls the switch S1 to be turned on, and at this time S2 is in an off state. Next, the sampling reference signal v _sns starts to rise from a negative value, and the time when v _sns rises to zero is time t1. After the t1 moment, v _sns is greater than zero, the output of the comparator CMP1 is a high level, and the time counting unit starts timing from the t1 moment. When the timing length tc reaches the time length parameter t _lp (shown as ΔT1 in FIG. 14 ), the time t2 is the time t2. At this moment, the controller 320 controls the switch S1 to be turned off, and then controls the switch S2 to be turned on. The moment when the sampling reference signal v _sns drops from a positive value to zero is the moment t3. After the t3 moment, v _sns is less than zero, the output of the comparator CMP1 is a low level, and the time counting unit starts counting from the t3 moment, when the timing length tc reaches the time length parameter _tlp (expressed as ΔT2 in Figure 14) moment is At time t4, at this moment, the controller 320 controls the switch S2 to be turned off, and then controls the switch S1 to be turned on.

Fig. 15 shows a working waveform diagram of a DC-DC voltage conversion device working in a light load mode according to an embodiment of the present application. Fig. 16 shows a working waveform diagram of a DC-DC voltage converting device working in a heavy load mode according to an embodiment of the present application. It can be known from Fig. 15 and Fig. 16 that in the light load mode, the time length parameter t _lp is relatively small, and in the heavy load mode, the time length parameter t _lp is relatively large. Therefore, the state of the load can be judged according to the size of t _lp , so that the switching between the light load mode and the load mode can be controlled. For example, if t _lp is less than a certain threshold, the DC-DC voltage conversion device may enter a light load mode.

Fig. 17 shows a working waveform diagram of a DC-DC voltage conversion device in a light load mode according to another embodiment of the present application. Fig. 18 shows a working waveform diagram of a DC-DC voltage conversion device in another embodiment of the present application working in a heavy load mode.

As shown in Figure 17 and Figure 18, when only the sampling of the resonant current i _cr is considered, t _lp tends to Ts/4 under no-load conditions (ΔTi2 in Figure 17), and t _lp approaches to at Ts/2 (refer to ΔTi1 in Figure 18). Wherein, Ts refers to the on-off cycle length of the switches S1 and S2. When only considering the sampling of the resonant voltage v _cr , in the case of no load, t _lp tends to zero (refer to ΔTv2 in Figure 17), and in the case of full load, t _lp tends to Ts/2 (refer to Fig. ΔTv1 in 18). Therefore, the parameters of the resistance and capacitance in the resonant sampling circuit can be adjusted to adjust the time from the zero-crossing point of the sampling reference signal v _sns to the turn-off time of the switch at different loads.

As shown in FIG. 17 , in the case of no load, t _lp =ΔTiv2, which is located between ΔTi2 and ΔTv2. As shown in FIG. 18 , under full load, t _lp =ΔTiv1 , which is between ΔTi1 and ΔTv1 . Therefore, by adjusting the size of the sampling resistor Rs and the second sampling capacitor _CS2 , the value of _tlp corresponding to no-load and full-load can be adjusted, so the load point for entering and exiting the light-load mode can be easily adjusted.

In the embodiment of this application, a comprehensive sampling circuit of resonant current i _cr and resonant voltage v _cr is introduced, that is, the sampling reference voltage v _sns can reflect the changes of resonant voltage v _cr and resonant current i _cr at the same time, so by using the sampling reference voltage v _{The sns} and the time length parameter _tlp control the on-off of the switch in the DC-DC voltage conversion device, which can realize fast loop control, thereby obtaining a faster dynamic response speed. In addition, by adjusting the resistance-capacitance parameters in the resonant signal sampling unit, the zero-crossing time of no-load and full-load can also be configured, so as to realize the accurate configuration of the control point of the no-load and full-load load point, and it is easier to realize the entry and exit point of the light-load mode adjustment, thereby improving the control efficiency.

By adjusting the resistance-capacitance parameters in the resonant signal sampling unit 330, it is easy to configure the time from zero crossing to switch off for different loads, or in other words, the ratio of the time from zero crossing to switch off time to the period, and the control of the load point is accurate. , It is easy to realize the adjustment of the entry and exit point of the light load mode, thereby improving the control efficiency.

FIG. 19 is a functional schematic diagram of a control method implemented by the controller 320 according to another embodiment of the present application. As shown in Figure 19, the output of the loop calculation unit is a time ratio k _lp , and the time counting unit is used to calculate the average period of the last N periods in addition to outputting the timing length tc

It can be calculated according to formula (3).

Wherein, T _S1 represents the first most recent cycle, T _SN represents the Nth most recent cycle, and N is an integer greater than 1.

Among them, the time length parameter t _lp is

The product of k _lp , that is

FIG. 20 is a working waveform diagram corresponding to the control method shown in FIG. 19 . As shown in Figure 20, at time t1, v _sns rises from a negative value to zero, the comparator CMP1 outputs a high level, and the time counting unit starts timing tc. At time t2, tc reaches t _lp , namely

(in FIG. 20 , t _lp here is represented as ΔT1), the controller 320 controls the switch S1 to be turned off, and controls the switch S2 to be turned on. At t3 moment, v _sns drops to zero from a positive value, the comparator CMP1 outputs high level, and the time counting unit starts timing tc. At time t4, tc reaches t _lp , namely

(in FIG. 20 , t _lp here is represented as ΔT2), the controller 320 controls the switch S2 to be turned off, and controls the switch S1 to be turned on.

In the control method shown in Figure 19 and Figure 20, the switching period calculated according to the sampling reference voltage V _sns is averaged to stabilize T _S , while the RC compensation part of the V _fb signal is omitted, which increases the V _fb feedback loop bandwidth, so that it can respond to load changes in a timely and effective manner, thereby improving the load response rate.

Those skilled in the art can appreciate that the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed by hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may use different methods to implement the described functions for each specific application, but such implementation should not be regarded as exceeding the scope of the present application.

Those skilled in the art can clearly understand that for the convenience and brevity of the description, the specific working process of the above-described system, device and unit can refer to the corresponding process in the foregoing method embodiment, which will not be repeated here.

In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods may be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or May be integrated into another system, or some features may be ignored, or not implemented. In another point, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection of devices or units may be in electrical, mechanical or other forms.

The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, each unit may exist separately physically, or two or more units may be integrated into one unit.

If the functions described above are realized in the form of software function units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including Several instructions are used to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (read-only memory, ROM), random access memory (random access memory, RAM), magnetic disk or optical disc and other media that can store program codes. .

The above is only a specific implementation of the application, but the scope of protection of the application is not limited thereto. Anyone familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the application. Should be covered within the protection scope of this application. Therefore, the protection scope of the present application should be determined by the protection scope of the claims.

Claims

A DC-DC DC-DC voltage conversion device, characterized in that it comprises:

The resonant conversion unit includes a high-frequency chopper circuit, a resonant cavity, a transformer and a rectification filter network, and the high-frequency chopper circuit includes switches S1 and S2;

a controller, configured to convert the DC voltage V in input into the high-frequency chopper circuit into a high-frequency square wave by controlling the on-off of the switches S1 and S2, and the resonant cavity and the transformer are used to receive the The high-frequency square wave is used to couple the electric energy from the primary side of the transformer to the secondary side, and the rectification and filtering network is used to convert the AC voltage coupled to the secondary side of the transformer into a DC voltage and output it as voltage Vout ;

a resonant signal sampling unit, configured to sample the resonant voltage v cr on the primary side of the transformer, and output a sampling reference voltage v sns , the sampling reference voltage v sns is used to reflect the resonant voltage v cr and resonant current i cr on the primary side of the transformer The change;

an output voltage sampling unit, configured to sample the output voltage V out of the resonant conversion unit, and output a feedback voltage V fb ;

The controller is also used to:

Obtain the sampling reference voltage v sns and the feedback voltage V fb ;

obtaining a time length parameter t lp according to the feedback voltage V fb ;

Outputting a switch control signal for controlling the switch S1 and the switch S2 to be turned on and off, the switch control signal is determined according to the time length parameter t lp and the sampling reference voltage vs sns .
The device according to claim 1, wherein the controller is specifically used for:

At the first moment t1 when the reference voltage v sns crosses zero from a negative value, start the first timing;

After the first timing reaches the second moment t2 of the time length parameter tlp , control the switch S1 to be in the off state, and then control the switch S2 to be in the on state;

After the third moment t3 when the reference voltage v sns crosses zero from a positive value, start the second timing;

After the second timing reaches the fourth moment t4 of the time length parameter tlp , the switch S2 is controlled to be in the off state, and then the switch S1 is controlled to be in the on state.
The device according to claim 1 or 2, wherein the controller is specifically used for:

Perform calculation processing on the feedback voltage V fb to obtain a proportional coefficient k lp ;

According to the formula
Obtain the time length parameter t lp , where,
Indicates the average period of the last N switching periods of the switch S1 or the switch S2, where N is an integer greater than 1.
The device according to any one of claims 1 to 3, wherein the time length parameter t lp meets at least one of the following conditions:

There is a negative correlation between the time length parameter t lp and the output voltage V out ;

There is a negative correlation between the time length parameter t lp and the magnitude of the load current.
The device according to any one of claims 1 to 4, wherein the resonance signal sampling unit comprises: a first sampling capacitor C S1 , a second sampling capacitor C S2 , and a sampling resistor Rs, and the first sampling The first end of the capacitor C S1 is used to receive the resonant voltage V cr on the primary side of the transformer, the second end of the first sampling capacitor C S1 is used to output the sampling reference voltage V sns , and the first sampling capacitor C S1 The sampling resistor Rs and the second sampling capacitor C S2 are connected in parallel between the second terminal of and the ground.
A control method for a DC-DC DC-DC voltage conversion device, characterized in that the DC-DC voltage conversion device includes: a resonant conversion unit, including a high-frequency chopper circuit, a resonant cavity, a transformer, and a rectification and filtering network. The high-frequency chopper circuit includes switches S1 and S2; a controller is used to convert the DC voltage V in input to the high-frequency chopper circuit into a high-frequency square wave by controlling the on-off of the switches S1 and S2, The resonant cavity and the transformer are used to receive the high-frequency square wave, and couple the electric energy from the primary side of the transformer to the secondary side, and the rectification and filtering network is used to couple the secondary side of the transformer The AC voltage on the side is converted into a DC voltage and used as the output voltage V out ; the resonance signal sampling unit is used to sample the resonance voltage v cr on the primary side of the transformer, and output the sampling reference voltage v sns , the sampling reference voltage v sns Used to reflect changes in the resonant voltage v cr and resonant current i cr on the primary side of the transformer; the output voltage sampling unit is used to sample the output voltage V out of the resonant conversion unit and output the feedback voltage V fb ;

The methods include:

The controller obtains the sampling reference voltage V sns and the feedback voltage V fb ;

The controller obtains a time length parameter t lp according to the feedback voltage V fb ;

The controller outputs a switch control signal for controlling the switching of the switch S1 and the switch S2, and the switch control signal is determined according to the time length parameter t lp and the sampling reference voltage v sns .
The method according to claim 6, wherein the controller outputs a switch control signal for controlling the switching of the switch S1 and the switch S2, comprising:

The controller starts a first timing at the first moment t1 when the reference voltage V sns crosses zero from a negative value;

After the first timing reaches the second moment t2 of the time length parameter tlp , the controller controls the switch S1 to be in the off state, and then controls the switch S2 to be in the on state;

The controller starts a second timing after the third moment t3 when the reference voltage V sns crosses zero from a positive value;

After the second timing reaches the fourth moment t4 when the time length parameter t lp is reached, the controller controls the switch S2 to be in the off state, and then controls the switch S1 to be in the on state.
The method according to claim 6 or 7, wherein the controller calculates and processes the feedback voltage V fb to obtain a time length parameter t lp , including:

Perform calculation processing on the feedback voltage V fb to obtain a proportional coefficient k lp ;

According to the formula
Obtain the time length parameter t lp , where,
Indicates the average period of the last N switching periods of the switch S1 or the switch S2, where N is an integer greater than 1.
The method according to any one of claims 6 to 8, wherein the time length parameter t lp meets at least one of the following conditions:

There is a negative correlation between the time length parameter t lp and the output voltage V out ;

There is a negative correlation between the time length parameter t lp and the magnitude of the load current.
The method according to any one of claims 6 to 9, wherein the resonance signal sampling unit comprises: a first sampling capacitor C S1 , a second sampling capacitor C S2 , and a sampling resistor Rs, and the first sampling The first end of the capacitor C S1 is used to receive the resonant voltage V cr on the primary side of the transformer, the second end of the first sampling capacitor C S1 is used to output the sampling reference voltage V sns , and the first sampling capacitor C S1 The sampling resistor Rs and the second sampling capacitor C S2 are connected in parallel between the second terminal of and the ground.
A power supply device, characterized in that the power supply device is used to supply power to a load, and the power supply device includes:

AC-DC AC-DC voltage conversion unit for converting AC voltage into DC voltage;

The DC-DC DC-DC voltage conversion device according to any one of claims 1 to 5, used for receiving the DC voltage output by the AC-DC voltage conversion unit and performing DC voltage conversion.