CN115621991A

CN115621991A - Voltage conversion device, control method and power supply equipment

Info

Publication number: CN115621991A
Application number: CN202211227478.9A
Authority: CN
Inventors: 戴宝磊; 汪波
Original assignee: Huawei Digital Power Technologies Co Ltd
Current assignee: Huawei Digital Power Technologies Co Ltd
Priority date: 2022-10-08
Filing date: 2022-10-08
Publication date: 2023-01-17

Abstract

The application provides a voltage conversion device, a control method and power supply equipment, wherein the voltage conversion device comprises a resonance conversion unit and a control circuit, and the control circuit is used for: acquiring a first voltage value at two ends of a resonant capacitor at a first moment and acquiring a second voltage value at two ends of the resonant capacitor at a second moment; obtaining ripple voltage according to the first voltage value and the second voltage value; and when the ripple voltage meets a preset condition, determining that the voltage conversion device is in a resonance unbalanced state, and turning off the first switch tube and/or the second switch tube. This application obtains ripple voltage through first voltage value and second voltage value, confirms that voltage transformation is in resonance unbalanced state and then turn off first switch tube and/or second switch tube when ripple voltage satisfies preset conditions to keep out voltage conversion equipment to continue to work in unbalanced state and cause the damage.

Description

Voltage conversion device, control method and power supply equipment

Technical Field

The present disclosure relates to the field of circuits, and in particular, to a voltage converting device, a control method and a power supply apparatus.

Background

A voltage converter such as a mobile phone adapter or a notebook adapter is usually used as a DC-DC (DC-DC) voltage converter. DC-DC voltage converters typically employ asymmetric Half-Bridge (AHB) flyback conversion circuits to achieve a wide range of output.

The AHB flyback converter circuit generally includes a main power transistor, an auxiliary power transistor, a transformer, a resonant capacitor, a resonant inductor, and the like. When the voltage at two ends of the resonant capacitor fluctuates periodically, the voltage conversion device is in a resonant unbalanced state. In the resonance unbalanced state, the voltage converting device may generate noise due to the coil vibration of the transformer and the piezoelectric effect of the resonance capacitor. And because the resonant inductor and the resonant capacitor are mutually coupled and excited, the current and the voltage of the AHB flyback conversion circuit can both have the risk of exceeding the standard, and further the voltage conversion device is damaged.

Disclosure of Invention

In view of this, the present application provides a voltage converting device, a control method and a power supply apparatus, which are capable of stopping the operation of the voltage converting device when the voltage across the resonant capacitor changes greatly by monitoring the change of the voltage across the resonant capacitor, so as to prevent the voltage converting device from generating noise and being damaged.

In a first aspect, the present application provides a voltage converting device, which includes a resonant converting unit and a control circuit, wherein the resonant converting unit includes a resonant capacitor, a first switch tube and a second switch tube, and the control circuit is configured to: acquiring a first voltage value at two ends of a resonant capacitor at a first moment and acquiring a second voltage value at two ends of the resonant capacitor at a second moment; obtaining ripple voltage according to the first voltage value and the second voltage value; and when the ripple voltage meets a preset condition, determining that the voltage conversion device is in a resonance unbalanced state, and turning off the first switch tube and/or the second switch tube.

It can be understood that the ripple voltage is obtained by obtaining the first voltage value and the second voltage value and obtaining the ripple voltage from the first voltage value and the second voltage value. When the ripple voltage meets the preset condition, the voltage conversion device is determined to be in a resonance unbalanced state, and then the first switch tube and/or the second switch tube are turned off, so that the voltage conversion device is prevented from being damaged due to the fact that the voltage conversion device continues to work in the unbalanced state.

With reference to the first aspect, in one possible implementation manner, the control circuit includes: the device comprises a control unit, a sampling module, an operation module and a threshold module; the control unit is used for: outputting a first switching signal at a first time and outputting a second switching signal at a second time; the first switching tube and/or the second switching tube are/is turned off when the enabling signal is received; the sampling module is used for: receiving a first switching signal, collecting voltages at two ends of a resonant capacitor, and outputting a first voltage value; the sampling module receives the second switching signal, collects the voltage at two ends of the resonant capacitor and outputs a second voltage value; the operation module is used for outputting ripple voltage according to the first voltage value and the second voltage value; the threshold module is used for determining that the voltage conversion device is in a resonance unbalanced state when the ripple voltage meets a preset condition, and outputting an enable signal to the control unit.

It can be understood that the control unit outputs different switching signals at different moments to control the sampling module to sample the voltages at the two ends of the resonant capacitor at different moments to obtain a first voltage value and a second voltage value. Whether the fluctuation of the voltage at the two ends of the resonant capacitor meets a preset condition or not is judged through the threshold module, and when the fluctuation meets the preset condition, a corresponding enabling signal is output to enable the control unit to turn off the first switch tube and/or the second switch tube, so that the voltage-avoiding conversion device continuously works in an unbalanced state to cause damage.

With reference to the first aspect, in a possible implementation manner, the voltage conversion device includes a resonance period, and the first time and the second time are the same time of two adjacent resonance periods; the preset condition is that the ripple voltage reaches the reference voltage.

It can be understood that the voltages at the two ends of the resonant capacitor are collected at the same time of two adjacent resonant periods of the voltage conversion device, so that the fluctuation condition of the voltages at the two ends of the resonant capacitor in the front period and the back period can be effectively obtained.

With reference to the first aspect, in a possible implementation manner, the first time is a time when the first switching tube or the second switching tube is turned on or a time when the first switching tube or the second switching tube is turned off in the first resonance period; the second time is the time corresponding to the first time in the second resonance period, wherein the first resonance period and the second resonance period are two adjacent resonance periods.

It can be understood that the acquisition time of the voltage can be accurately controlled and the error can be reduced by acquiring the voltage at the two ends of the resonant capacitor at the moment when the first switching tube or the second switching tube is switched on or switched off.

With reference to the first aspect, in a possible implementation manner, the operation module includes a difference unit and an absolute value unit, the difference unit is configured to receive the first voltage value and the second voltage value, perform a difference operation, and output a difference signal, and the absolute value unit is configured to take an absolute value of the difference signal and output a ripple voltage; the threshold module comprises a comparison unit, and the comparison unit is used for receiving and comparing the reference voltage and the ripple voltage, and outputting an enable signal to the control unit when the ripple voltage reaches the reference voltage.

It is understood that the fluctuation of the voltage across the resonant capacitor in the two preceding and following periods can be obtained by setting the difference unit, and the fluctuation value can be changed into a positive number by setting the absolute value unit so as to be input to the comparison unit for comparison with the preset threshold/reference voltage.

With reference to the first aspect, in a possible implementation manner, the voltage conversion device includes a resonance period, where the resonance period includes a first dead time and a second dead time, where the first time is a start point or an end point of the first dead time, and the second time is a start point or an end point of the second dead time; the first dead time is the time from the turn-off moment of the first switch tube to the turn-on moment of the second switch tube, and the second dead time is the time from the turn-off moment of the second switch tube to the turn-on moment of the first switch tube; the preset condition is that the ratio of the ripple voltage to the first voltage value reaches the reference voltage, or the ratio of the ripple voltage to the second voltage value reaches the reference voltage.

It can be understood that the voltages at the two ends of the resonant capacitor collected at the starting point or the end point of the first dead zone and the second dead zone are near the valley value and the peak value of the voltage of the resonant capacitor, so that the ripple voltage can be increased as much as possible, and the error in numerical value comparison can be reduced as much as possible. The ratio of the ripple voltage to the first voltage value or the second voltage value is calculated, and then the numerical comparison is carried out through the ratio, so that the influence caused by the change of the output voltage of the voltage conversion device can be reduced, and the voltage conversion device is suitable for wide-range output.

With reference to the first aspect, in a possible implementation manner, the first switch tube is a main switch tube, the first time is a time when the second switch tube is turned on, and the second time is a time when the first switch tube is turned on.

With reference to the first aspect, in a possible implementation manner, the operation module includes a difference unit and an absolute value unit, the difference unit is configured to receive the first voltage value and the second voltage value, perform a difference operation, and output a difference signal, and the absolute value unit is configured to take an absolute value of the difference signal and output a ripple voltage; the threshold module comprises a ratio unit and a comparison unit; the ratio unit is used for receiving the ripple voltage and the first voltage value, or receiving the ripple voltage and the second voltage value, and obtaining the ratio of the ripple voltage to the first voltage value or the ratio of the ripple voltage to the second voltage value to output a ratio signal; the comparison unit is used for receiving the reference voltage and the ratio signal, comparing the reference voltage and the ratio signal, and outputting an enable signal to the control unit when the ratio signal reaches the reference voltage.

It can be understood that the fluctuation of the voltage at two ends of the resonant capacitor between the peak value and the valley value can be obtained by setting the operation module, and the influence caused by the change of the output voltage of the voltage conversion device can be reduced by setting the ratio unit so as to adapt to the voltage conversion device with wide-range output.

With reference to the first aspect, in a possible implementation manner, the sampling module includes a first switch, a second switch, a first sample-and-hold unit, and a second sample-and-hold unit; the first end of the first switch is connected to two ends of the resonant capacitor, the second end of the first switch is connected to the first sampling and holding unit, and the third end of the first switch is connected to the control unit; the first end of the second switch is connected to two ends of the resonant capacitor, the second end of the second switch is connected to the second sampling and holding unit, and the third end of the second switch is connected to the control unit; the first sampling and holding unit is used for outputting a first voltage value when the first switch is controlled to be closed by a first switch signal; the second sampling and holding unit is used for outputting a second voltage value when the second switch is controlled to be closed by a second switch signal.

It can be understood that the sampling module receives different switching signals output by the control unit at different times, so as to sample and hold the voltage across the resonant capacitor at different times and obtain the first voltage value and the second voltage value.

In a second aspect, the present application further provides a control circuit, where the control circuit is applied to a voltage converting device, the voltage converting device includes a resonant converting unit and a control circuit, the resonant converting unit includes a resonant capacitor, a first switch tube and a second switch tube, and the control circuit is configured to: acquiring a first voltage value at two ends of a resonant capacitor at a first moment and acquiring a second voltage value at two ends of the resonant capacitor at a second moment; obtaining ripple voltage according to the first voltage value and the second voltage value; and when the ripple voltage meets a preset condition, determining that the voltage conversion device is in a resonance unbalanced state, and turning off the first switch tube and/or the second switch tube.

With reference to the second aspect, in one possible implementation manner, the control circuit includes: the device comprises a control unit, a sampling module, an operation module and a threshold module; the control unit is used for: outputting a first switching signal at a first time and outputting a second switching signal at a second time; the first switch tube and/or the second switch tube are/is turned off when the enabling signal is received; the sampling module is used for: receiving a first switching signal, collecting voltages at two ends of a resonant capacitor, and outputting a first voltage value; the sampling module receives the second switching signal, collects the voltage at two ends of the resonant capacitor and outputs a second voltage value; the operation module is used for outputting ripple voltage according to the first voltage value and the second voltage value; the threshold module is used for determining that the voltage conversion device is in a resonance unbalanced state when the ripple voltage meets a preset condition, and outputting an enabling signal to the control unit.

With reference to the second aspect, in a possible implementation manner, the voltage conversion device includes a resonance period, and the first time and the second time are the same time of two adjacent resonance periods; the preset condition is that the ripple voltage reaches the reference voltage.

With reference to the second aspect, in a possible implementation manner, the first time is a time when the first switching tube or the second switching tube is turned on or a time when the first switching tube or the second switching tube is turned off in the first resonance period; the second time is the time corresponding to the first time in the second resonance period, wherein the first resonance period and the second resonance period are two adjacent resonance periods.

With reference to the second aspect, in a possible implementation manner, the operation module includes a difference unit and an absolute value unit, the difference unit is configured to receive the first voltage value and the second voltage value, perform a difference operation, and output a difference signal, and the absolute value unit is configured to take an absolute value of the difference signal and output a ripple voltage; the threshold module comprises a comparison unit, and the comparison unit is used for receiving and comparing the reference voltage and the ripple voltage, and outputting an enable signal to the control unit when the ripple voltage reaches the reference voltage.

With reference to the second aspect, in a possible implementation manner, the voltage conversion device includes a resonance period, and the resonance period includes a first dead time and a second dead time, where the first time is a start point or an end point of the first dead time, and the second time is a start point or an end point of the second dead time; the first dead time is the time from the turn-off moment of the first switch tube to the turn-on moment of the second switch tube, and the second dead time is the time from the turn-off moment of the second switch tube to the turn-on moment of the first switch tube; the preset condition is that the ratio of the ripple voltage to the first voltage value reaches the reference voltage, or the ratio of the ripple voltage to the second voltage value reaches the reference voltage.

With reference to the second aspect, in a possible implementation manner, the first switching tube is a main switching tube, the first time is a time when the second switching tube is turned on, and the second time is a time when the first switching tube is turned on.

With reference to the second aspect, in a possible implementation manner, the operation module includes a difference unit and an absolute value unit, the difference unit is configured to receive the first voltage value and the second voltage value, perform a difference operation, and output a difference signal, and the absolute value unit is configured to take an absolute value of the difference signal and output a ripple voltage; the threshold module comprises a ratio unit and a comparison unit; the ratio unit is used for receiving the ripple voltage and the first voltage value, or receiving the ripple voltage and the second voltage value, and obtaining the ratio of the ripple voltage to the first voltage value or the ratio of the ripple voltage to the second voltage value to output a ratio signal; the comparison unit is used for receiving the reference voltage and the ratio signal, comparing the reference voltage and the ratio signal, and outputting an enable signal to the control unit when the ratio signal reaches the reference voltage.

In a third aspect, the present application further provides a method for controlling a voltage converting device, where the voltage converting device includes a resonant converting unit and a control circuit, the resonant converting unit includes a resonant capacitor, a first switching tube and a second switching tube, and the method includes: acquiring a first voltage value at two ends of a resonant capacitor at a first moment and acquiring a second voltage value at two ends of the resonant capacitor at a second moment; obtaining ripple voltage according to the first voltage value and the second voltage value; and when the ripple voltage meets a preset condition, determining that the voltage conversion device is in a resonance unbalanced state, and turning off the first switch tube and/or the second switch tube.

With reference to the third aspect, in a possible implementation manner, the control circuit includes a control unit, and the first time and the second time are the same time of two adjacent resonance periods of the voltage conversion device; the preset condition is that the ripple voltage reaches the reference voltage.

With reference to the third aspect, in a possible implementation manner, the voltage conversion device includes a resonance period, and the first time and the second time are the same times of two adjacent resonance periods; the preset condition is that the ripple voltage reaches the reference voltage.

With reference to the third aspect, in a possible implementation manner, the first time is a time when the first switching tube or the second switching tube is turned on or a time when the first switching tube or the second switching tube is turned off in the first resonance period; the second time is the time corresponding to the first time in the second resonance period, wherein the first resonance period and the second resonance period are two adjacent resonance periods.

With reference to the third aspect, in a possible implementation manner, obtaining a ripple voltage according to the first voltage value and the second voltage value includes: outputting a difference signal after the first voltage value and the second voltage value are subjected to difference; taking an absolute value of the difference signal and outputting ripple voltage; when ripple voltage satisfies the preset condition, confirm that voltage conversion device is in resonance unbalanced state to turn off first switch tube and/or second switch tube, include: comparing the reference voltage with the ripple voltage, determining that the voltage conversion device is in a resonance unbalanced state when the ripple voltage reaches the reference voltage, and outputting an enable signal; and the first switch tube and/or the second switch tube are/is turned off according to the enable signal.

With reference to the third aspect, in a possible implementation manner, the voltage conversion device includes a resonance period, where the resonance period includes a first dead time and a second dead time, where the first time is a start point or an end point of the first dead time, the second time is a start point or an end point of the second dead time, the first dead time is a time from a turn-off time of the first switching tube to a turn-on time of the second switching tube, and the second dead time is a time from a turn-off time of the second switching tube to a turn-on time of the first switching tube; the preset condition is that the ratio of the ripple voltage to the first voltage value reaches the reference voltage, or the ratio of the ripple voltage to the second voltage value reaches the reference voltage.

With reference to the third aspect, in a possible implementation manner, the first switch tube is a main switch tube, the first time is a time when the second switch tube is turned on, and the second time is a time when the first switch tube is turned on.

With reference to the third aspect, in a possible implementation manner, obtaining a ripple voltage according to the first voltage value and the second voltage value includes: outputting a difference signal after the difference is made between the first voltage value and the second voltage value; taking an absolute value of the difference signal and outputting ripple voltage; when ripple voltage satisfies the preset condition, confirm that voltage conversion device is in resonance unbalanced state to turn off first switch tube and/or second switch tube, include: comparing the reference voltage with a ratio signal, determining that the voltage conversion device is in a resonance unbalanced state when the ratio signal reaches the reference voltage, and outputting an enable signal, wherein the ratio signal is the ratio of ripple voltage to a first voltage value or the ratio of the ripple voltage to a second voltage value; and the first switch tube and/or the second switch tube are/is turned off according to the enabling signal.

In a fourth aspect, the present application further provides a power supply apparatus, including: an AC-DC voltage conversion unit for converting an AC voltage into a DC input voltage; the voltage conversion device is used for receiving the direct current input voltage output by the AC-DC voltage conversion unit, converting the direct current voltage and outputting direct current output voltage; wherein, voltage conversion equipment includes resonance transform unit and control circuit, and resonance transform unit includes resonant capacitor, first switch tube and second switch tube, and control circuit is used for: acquiring a first voltage value at two ends of a resonant capacitor at a first moment and acquiring a second voltage value at two ends of the resonant capacitor at a second moment; obtaining ripple voltage according to the first voltage value and the second voltage value; and when the ripple voltage meets a preset condition, determining that the voltage conversion device is in a resonance unbalanced state, and turning off the first switch tube and/or the second switch tube.

In addition, for technical effects brought by any possible implementation manner in the second aspect to the fourth aspect, reference may be made to technical effects brought by different implementation manners in the first aspect, and details are not described here.

Drawings

Fig. 1A and fig. 1B are schematic structural diagrams of an asymmetric half-bridge conversion unit according to an embodiment of the present application.

Fig. 2 is a waveform diagram of an operation of an asymmetric half-bridge conversion unit in a resonance unbalanced state according to an embodiment of the present application.

Fig. 3 is a schematic structural diagram of a voltage conversion device according to an embodiment of the present application.

Fig. 4 is a waveform diagram of an operation of the asymmetric half-bridge conversion unit in an overcurrent state according to the second embodiment of the present application.

Fig. 5 is a schematic structural diagram of a voltage conversion device according to a second embodiment of the present application.

Fig. 6 is another schematic diagram of the control circuit in fig. 5.

Fig. 7 is a schematic structural diagram of a voltage conversion device according to a third embodiment of the present application.

Fig. 8 is a schematic flowchart of a method for controlling a voltage conversion device according to an embodiment of the present application.

Fig. 9 is a schematic structural diagram of a power supply device according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.

"and/or" herein is merely an association describing an associated object, and means that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone.

In the description of the present application, the words "first", "second", and the like are used only for distinguishing different objects, and do not limit the number and execution order, and the words "first", "second", and the like do not necessarily limit the difference. Furthermore, the terms "comprising" and "having," as well as any variations thereof, are intended to cover non-exclusive inclusions.

The technical solution of the present application is further described in detail below with reference to the accompanying drawings.

In the embodiment of the present application, the voltage conversion device includes, but is not limited to, a power adapter of a terminal device, an industrial power supply, an aerospace power supply, a charger, a mobile power supply, and other power supply devices.

The voltage converting device is usually a Direct Current To Direct Current (DC-DC) voltage converter. DC-DC voltage converters typically employ asymmetric Half-Bridge (AHB) flyback conversion circuits to achieve a wide range of output.

For example, referring to fig. 1A, a schematic diagram of an asymmetric half-bridge conversion unit 100 according to an embodiment of the present application is shown. In this embodiment, the asymmetric half-bridge converting unit 100 may be, for example, a DC-DC converter, and is configured to perform resonant conversion on a received DC input voltage and output a DC output voltage.

As shown in fig. 1A, the asymmetric half-bridge converter unit 100 includes an AHB flyback converter circuit 11 and a rectifier filter circuit 12. The AHB flyback converter circuit 11 includes a first switching tube S1, a first switching tube S2, a transformer Tr, a resonant inductor Lr, and a resonant capacitor Cr. The primary side excitation inductance of the transformer Tr is denoted by Lm.

The AHB flyback converter circuit 11 is configured to receive a dc input voltage Vin. The first switching tube S1 and the second switching tube S2 in the AHB flyback converter circuit 11 are connected in series. In some embodiments, the first switch tube S1 and the second switch tube S2 may be field-effect transistors (FETs) made of silicon carbide (silicon, si) or gallium nitride (GaN) which is a third generation wide-forbidden semiconductor material.

Illustratively, the drain of the first switch tube S1 receives the dc input voltage Vin, the source of the first switch tube S1 is connected to the drain of the second switch tube S2, and the source of the second switch tube S2 is connected to the ground. The gate of the first switch tube S1 receives a first driving signal Vgs1 from a control circuit (not shown), and the gate of the second switch tube S2 receives a second driving signal Vgs2 from the control circuit. The first switch tube S1 and the second switch tube S2 can be turned on or off by the first driving signal Vgs1 and the second driving signal Vgs2.

The transformer Tr includes a primary winding Np and a secondary winding Ns. The primary winding Np and the secondary winding Ns of the transformer Tr are coupled by a magnetic core. The primary winding Np of the transformer Tr is connected in parallel between the source and the drain of the second switching tube S2 through the resonant capacitor Cr and the resonant inductor Lr. Specifically, the dotted terminal of the primary winding Np is connected to the first terminal of the resonant inductor Lr. The second end of the resonant inductor Lr is connected to the source of the first switching tube S1 and the drain of the second switching tube S2. The synonym end of the primary winding Np is connected with the first end of the resonant capacitor Cr, and the second end of the resonant capacitor Cr is connected with the source electrode of the second switching tube S2. The secondary winding Ns of the transformer Tr passes through the rectifying filter circuit 12 to obtain the dc output voltage Vout.

It is understood that, in the embodiment of the present application, the resonant inductance Lr includes the leakage inductance and the external inductance of the transformer Tr. Of course, in other embodiments, the resonant inductor Lr may be integrated entirely within the transformer Tr.

The rectifying and filtering circuit 12 is configured to receive power supplied by the transformer Tr in the AHB flyback converter circuit 11, and output a dc output voltage Vout to supply power to a load. That is, the AHB flyback converter circuit 11 supplies power to the load through the rectifier filter circuit 12.

In one possible implementation, the rectifying and filtering circuit 12 includes a rectifying diode D1 and an output capacitor Co. The anode of the rectifier diode D1 is connected to the synonym terminal of the secondary winding Ns, and the cathode of the rectifier diode D1 is connected to the first terminal of the output capacitor Co. And the second end of the output capacitor Co is connected with the dotted end of the secondary winding Ns and is grounded.

For another example, please refer to fig. 1B, which is a schematic diagram of an asymmetric half-bridge converting unit 100a according to another embodiment of the present application. As shown in fig. 1B, the asymmetric half-bridge converter unit 100a includes an AHB flyback converter circuit 11a and a rectifier/filter circuit 12. The AHB flyback converter circuit 11a includes a first switching tube S1, a second switching tube S2, a transformer Tra, a resonant inductor Lr, and a resonant capacitor Cr. The rectifying and filtering circuit 12 includes a rectifying diode D1 and an output capacitor Co.

It will be appreciated that in the embodiment shown in fig. 1B, the asymmetric half-bridge conversion cell 100a differs from the asymmetric half-bridge conversion cell 100 in that: the transformer Tra and the first switching tube S1 in the AHB flyback converter circuit 11a are connected in a different manner.

Specifically, as shown in fig. 1B, the primary winding Np of the transformer Tra is connected in parallel between the source and the drain of the first switching tube S1 through the resonant capacitor Cr and the resonant inductor Lr.

It can be understood that, as shown in fig. 1A and fig. 1B, the asymmetric half-bridge converting unit 100/100a can adjust the dc output voltage Vout by adjusting the switching frequencies of the first switching transistor S1 and the second switching transistor S2.

Fig. 2 is a waveform diagram of an operation of an asymmetric half-bridge converting unit in a resonant unbalanced state according to an embodiment of the present application. Here, the asymmetric half-bridge converting unit may be the asymmetric half-bridge converting unit 100 shown in fig. 1A, or may be the asymmetric half-bridge converting unit 100a shown in fig. 1B. For convenience of description, the following description will take the asymmetric half-bridge converting unit 100 in fig. 1A as an example.

As shown in fig. 2, fig. 2 shows three resonant periods of the asymmetric half-bridge converting unit 100, namely, a first period T1, a second period T2, and a third period T3. Here, the first period T1 is from the time T0 to the time T5. The second period T2 is from time T5 to time T10. From time T10 to time T15 is a third period T3.

Illustratively, at the time T0 to T1 of the first period T1, the first driving signal Vgs1 is in a high-level state and the second driving signal Vgs2 is in a low-level state. At time t1 to t2, both the first drive signal Vgs1 and the second drive signal Vgs2 are in a low-level state. At time t2 to t4, the first drive signal Vgs1 is in a high-level state, and the second drive signal Vgs2 is in a low-level state. At time t4 to t5, both the first drive signal Vgs1 and the second drive signal Vgs2 are in a low level state.

It can be understood that the variation rule of the alternating turn-on of the first driving signal Vgs1 and the second driving signal Vgs2 in the second period T2 and the third period T3 is the same as the first period T1, and is not repeated herein.

The waveform diagrams of the asymmetric half-bridge converting unit 100 in three resonant cycles (i.e. the first cycle T1, the second cycle T2 and the third cycle T3) are described in detail below.

First period T1:

it will be appreciated that the asymmetric half-bridge conversion unit 100 is in the charging phase from time t0 to time t3, as shown in fig. 2. When the asymmetric half-bridge converting unit 100 is in a short-circuit state, the exciting inductor current I on the primary side of the transformer Tr is affected by the control loop (e.g. the first driving signal Vgs1 and the second driving signal Vgs 2) _LM Will increase (at I) _LM Before reaching peak value and resonant inductance current I _Lr Coincident). In order to achieve the exciting inductive current I _LM The on-time of the first switch tube S1 is increased correspondingly, i.e. the time between t0 and t1 is increased.As the charging time increases, the resonant capacitor voltage Vcr continues to increase until the resonant inductor current I at time t3 _Lr The charging phase is ended when the voltage changes from positive to negative. At this time, the charging time is too long, and the resonant capacitor Cr is overcharged, that is, at the end of charging, the voltage value Vcr of the resonant capacitor Cr reaches Vpeak1, which is higher than the voltage value Vcr _ ref of the resonant capacitor Cr in the equilibrium state and at the end of charging.

At time t3 to t5, the asymmetric half-bridge conversion unit 100 is in the discharge phase. Since the output of the asymmetric half-bridge conversion unit 100 is in a short circuit state, the discharge slope is large, i.e., the discharge rate is fast. And the current state change rate is obviously faster than the rate of driving signal adjustment performed by the control loop, so that the over-discharge phenomenon of the resonant capacitor Cr occurs. Thus, when the discharge is completed, the voltage value Vcr of the resonance capacitor Cr at time t5 is Vcr2, which is lower than the voltage value Vcr1 of the resonance capacitor Cr at time t0. As shown in fig. 2, vcr1= Vcr2 +. DELTA.Vcr.

Second period T2:

at times t5 to t8, the asymmetric half-bridge converter cell 100 is in the charging phase. Understandably, the exciting inductance current I _Lm The charging slope of (2) is related to the initial voltage value of the voltage value Vcr of the resonant capacitor Cr, and can be specifically obtained from formula (1).

Since the voltage value Vcr (i.e. the initial voltage value) of the resonant capacitor Cr at the time t5 is Vcr2, which is smaller than the voltage value of the resonant capacitor Cr at the charging end time in the equilibrium state, for example, smaller than Vcr1 at the time t0, vin-Vcr of the formula (1) is larger, so that the charging slope is larger, that is, the charging rate is faster, and the same exciting inductor current I is achieved _LM The time of the peak becomes shorter. Therefore, the charging time of the second period T2 (i.e., the elapsed time at times T5 to T8) is greater than the charging time of the first period T1 (i.e., the elapsed time at times T0 to T3). That is, in the second period T2, it takes less time to make the exciting inductor currentI _LM Reaching a peak to complete charging. Since the charging time becomes short, the voltage value of the resonance capacitance Cr at the charging end time (i.e., time t 8) of the voltage value Vcr of the resonance capacitance Cr is Vpeak2, which is lower than the voltage value Vcr _ ref of the resonance capacitance Cr at the charging end time in the equilibrium state.

At time t8 to t10, the asymmetric half-bridge conversion unit 100 is in the discharge phase. The voltage value at the discharge start time is Vpeak2, and since it is not high (compared to Vcr _ ref), the discharge slope is not large. Although there is an overdischarge phenomenon, the voltage value Vcr3 of the resonant capacitor Cr at the time t10, which is the discharge end time, is also higher than the voltage value Vcr1 of the resonant capacitor Cr at the time t0.

Third cycle T3:

at time t10 to t13, the asymmetric half-bridge converter cell 100 is in the charging phase. Since the voltage value Vcr3 of the resonant capacitor Cr at the time t10 is higher, and Vin-Vcr in the formula (1) is smaller, the charging slope is smaller, namely the charging rate is slower, and the same excitation inductance current I is achieved _LM The time of the peak becomes longer. Therefore, the voltage value Vpeak3 of the resonant capacitor Cr at the time of the third period T3, i.e., at the time T13 is higher than the voltage value Vpeak1 of the resonant capacitor Cr at the time of the first period T1.

At time t13 to t15, the asymmetric half-bridge conversion unit 100 is in the discharge phase. Since the voltage value Vpeak3 at which discharge starts is high, the discharge slope is also large. Even if there is the over-discharge phenomenon, the voltage value Vcr4 of the resonant capacitor Cr at the discharge end time, i.e., at the time T15, returns to almost the same level as the charge start time of the first period T1, i.e., at the time T0. In this way, the asymmetric half-bridge conversion unit 100 achieves loop stabilization.

Obviously, as described above, when the resonant capacitor voltage Vcr has a periodic fluctuation, for example, the resonant capacitor voltage value at the end of charging is higher and lower than the resonant capacitor voltage value Vcr _ ref at the end of charging in the balanced state in consecutive resonant cycles, the asymmetric half-bridge converting unit 100 is in the resonant unbalanced state. In the resonance unbalanced state, due to the coil vibration of the transformer Tr and the piezoelectric effect of the resonance capacitor Cr, noise may be generated in the asymmetric half-bridge converting unit 100. And because the resonant inductor Lr and the resonant capacitor Cr are mutually coupled and excited, both the current and the voltage of the asymmetric half-bridge conversion unit 100 exceed the standards, thereby causing the risk of damage to the asymmetric half-bridge conversion unit 100.

In order to solve the above problem, embodiments of the present application provide a voltage conversion device. The voltage conversion device comprises a control circuit and a resonance conversion unit, wherein the control circuit is used for monitoring the fluctuation (namely ripple voltage) of the voltage at two ends of the resonance capacitor Cr, and determining that the voltage conversion device is in a resonance unbalanced state when the ripple voltage meets a preset condition, so that the first switch tube S1 and/or the second switch tube S2 are turned off, and the voltage conversion device is prevented from continuously working in the unbalanced state to generate noise or damage.

The circuit structure and the operation principle of the voltage conversion device are explained in detail through the first to third embodiments.

The first embodiment is as follows:

referring to fig. 3, a schematic structural diagram of a voltage converting device 200 according to a first embodiment of the present application is shown.

As shown in fig. 3, the voltage conversion device 200 includes a resonance conversion unit 210 and a control circuit 220. The resonant converting unit 210 is configured to convert the received dc input voltage Vin and output a dc output voltage Vout. The resonant converting unit 210 includes a resonant converting circuit 211 and a rectifying and filtering circuit 212. The resonant converting circuit 211 is configured to couple the dc input voltage Vin from the primary side of the transformer Tr to the secondary side. The rectifying-smoothing circuit 212 is configured to convert the ac voltage coupled to the secondary side of the transformer Tr into a dc voltage, and output the dc voltage as a dc output voltage Vout.

It is understood that in the embodiment of the present application, the circuit structure of the resonant converting unit 210 may adopt the asymmetric half-bridge converting unit 100/100a shown in fig. 1A and 1B, and may also adopt other circuit topologies. For convenience of description, the resonant converting unit 210 is illustrated as the structure of the asymmetric half-bridge converting unit 100 in fig. 1A.

It is understood that, in the embodiment of the present application, the control circuit 220 is configured to:

the first voltage value V1 is obtained at the first time and the second voltage value V2 is obtained at the second time.

The first voltage value V1 and the second voltage value V2 are both used for representing voltages at two ends of the resonant capacitor Vcr.

It is understood that, in the embodiment of the present application, the control circuit 220 is further configured to:

and obtaining the ripple voltage according to the first voltage value V1 and the second voltage value V2.

when the ripple voltage meets a preset condition, it is determined that the voltage conversion device 200 is in a resonance unbalanced state, and the first switching tube S1 and/or the second switching tube S2 are turned off.

Obviously, the control circuit 220 obtains the ripple voltage by obtaining the first voltage value V1 and the second voltage value V2, and obtaining the ripple voltage through the first voltage value V1 and the second voltage value V2. When the ripple voltage meets the preset condition, it is determined that the voltage conversion device 200 is in a resonance unbalanced state, and the first switching tube S1 and/or the second switching tube S2 are turned off, so as to prevent the voltage conversion device 200 from continuing to work in an unbalanced state and being damaged.

As shown in fig. 3, the control circuit 220 includes a control unit 221 and a first processing module 2201, wherein the first processing module 2201 includes a sampling module 222, an operation module 223 and a threshold module 224.

The control unit 221 is configured to output the first switching signal P1 and the second switching signal P2 at the same time of two adjacent resonant periods of the voltage conversion device 200, that is, at a first time and a second time, respectively.

It can be understood that the voltage at the two ends of the resonant capacitor Cr is collected at the same time of two adjacent resonant periods of the voltage conversion device 200, so that the fluctuation condition of the voltage at the two ends of the resonant capacitor Cr in the two front and back periods can be effectively obtained.

In a possible implementation manner, the first time is a time when the first switching tube S1 or the second switching tube is turned on in a first resonance period, or the first switching tube S1 or the second switching tube S2 is turned off, and the second time is a time when the first switching tube S1 or the second switching tube S2 is turned on in a second resonance period, or the first switching tube S1 or the second switching tube S2 is turned off, where the first resonance period and the second resonance period are two adjacent resonance periods of the voltage conversion device 200.

That is, specific times of the first time when the control unit 221 outputs the first switching signal P1 and the second time when the control unit 221 outputs the second switching signal P2 are not limited herein. For example, in one possible implementation manner, the first switching tube S1 may output the first switching signal P1 and the second switching signal P2 when the first switching tube S1 is turned on in two adjacent resonance periods. For another example, in another possible implementation manner, the first switching signal P1 and the second switching signal P2 may be respectively output when the first switching tube S1 is turned off in two adjacent resonance periods. For another example, in another possible implementation manner, the first switching signal P1 and the second switching signal P2 are respectively output when the second switching tube S2 is turned on in two adjacent resonance periods. For another example, in another possible implementation manner, the first switching signal P1 and the second switching signal P2 are respectively output when the second switching tube S2 is turned off in two adjacent resonance periods. For another example, in some other implementations, the first switching tube S1 is turned on (or turned off) in two adjacent resonance periods, and then delayed by a fixed time period, and the first switching signal P1 and the second switching signal P2 are respectively output at the end of the fixed time period. For another example, in some other implementations, the second switching tube S2 is turned on (or off) in two adjacent resonance periods, and then delayed by a fixed time, and the first switching signal P1 and the second switching signal P2 are respectively output at the end of the fixed time.

The sampling module 222 is configured to receive a first switching signal P1 and a second switching signal P2, collect voltages at two ends of the resonant capacitor Cr under the control of the first switching signal P1 and the second switching signal P2, output a first voltage value V1 based on the first switching signal P1, and output a second voltage value V2 based on the second switching signal P2. That is, the first sampling module 222 collects the voltage across the resonant capacitor Cr when receiving the first switching signal P1 and outputs the voltage as the first voltage value V1, and collects the voltage across the resonant capacitor Cr when receiving the second switching signal P2 and outputs the voltage as the second voltage value V2.

As shown in fig. 3, in some embodiments, the control circuit 220 further includes a first resistor R1 and a second resistor R2 connected in series across the resonant capacitor Cr. Illustratively, a first end of the first resistor R1 is connected to ground, a first end of the second resistor R2 is connected to a second end of the first resistor R1, and a second end of the second resistor R2 is connected to a synonym end of the primary winding Np. The connection node between the first resistor R1 and the second resistor R2 is connected to the control circuit 220, and is configured to output the voltage across the resonant capacitor Cr.

As shown in fig. 3, in one possible implementation, the sampling module 222 includes a first switch Q1, a second switch Q2, a first Sample-and-Hold (Sample/Hold, S/H) unit 2221, and a second Sample-and-Hold unit 2222. A first terminal of the first switch Q1 is connected to two terminals of the resonant capacitor Cr, a second terminal of the first switch Q1 is connected to the first sample-and-hold unit 2221, and a third terminal of the first switch Q1 is connected to the control unit 221. The first switch Q1 can be closed when receiving the first switch signal P1, i.e. controlled to be closed by the first switch signal P1. A first terminal of the second switch Q2 is connected to two terminals of the resonant capacitor Cr, a second terminal of the second switch Q2 is connected to the second sample-and-hold unit 2222, and a third terminal of the second switch Q2 is connected to the control unit 221. The second switch Q2 can be closed upon receiving the second switching signal P2, i.e. controlled to be closed by the second switching signal P2.

The first sample-and-hold unit 2221 is configured to collect the voltage at two ends of the resonant capacitor Cr and output a first voltage value V1 when the first switch Q1 is controlled to be closed by the first switch signal P1. The second sample-and-hold unit 2222 is configured to collect the voltage at two ends of the resonant capacitor Cr and output a second voltage value V2 when the second switch Q2 is controlled to be closed by the second switch signal P2.

The operation module 223 is configured to generate a ripple voltage (e.g., a first ripple voltage) according to the first voltage value V1 and the second voltage value V2.

In one possible implementation, the operation module 223 includes a difference unit 2231 and an Absolute value (ABS) unit 2232. The difference unit 2231 may be, for example, a subtractor. The specific circuit configuration of the absolute value unit 2232 is not limited herein, and may be, for example, a circuit including an adder and a diode. The difference unit 2231 is configured to receive the first voltage value V1 and the second voltage value V2, and output a difference signal after the difference between the first voltage value V1 and the second voltage value V2.

The absolute value unit 2232 is configured to perform absolute value processing (i.e., taking an absolute value) on the difference signal and output a first ripple voltage. It can be understood that, since the magnitude of the voltage values at two ends of the resonant capacitor Cr acquired at the same time in two adjacent resonant periods cannot be determined, for example, the first voltage value V1 may be larger than the second voltage value V2, and the second voltage value V2 may also be larger than the first voltage value V1. Therefore, by setting the absolute value unit 2232, the absolute value of the difference signal output by the difference unit 2231 is processed, so as to effectively ensure that the first ripple voltage finally output by the operation module 223 is a positive value, and the first ripple voltage can be directly input to the threshold module 224.

The threshold module 224 is configured to determine that the voltage conversion device 200 is in a resonant unbalanced state and turn off the first switching tube S1 and/or the second switching tube S2 when the first ripple voltage meets a preset condition. Specifically, the threshold module 224 is configured to receive the first reference voltage Vref1 and the first ripple voltage, and output the first enable signal E1 to the control unit 221 when the first ripple voltage satisfies a preset condition. The first enable signal E1 is used for driving the control unit 221 to control the first switch tube S1 or the second switch tube S2 to be turned off. Of course, in other embodiments, the first enable signal E1 can also be used to drive the control unit 221 to control the first switch tube S1 and the second switch tube S2 to be turned off simultaneously. That is, the first enable signal E1 is used for the driving control unit 221 to control the first switch tube S1 and/or the second switch tube S2 to be turned off.

In one possible implementation, the preset condition is that the first ripple voltage reaches the first reference voltage Vref1. The threshold module 224 includes a comparison unit 2241. The comparing unit 2241 is configured to receive and compare the first reference voltage Vref1 and the first ripple voltage, and output a first enable signal E1 to the control unit 221 when the first ripple voltage reaches the first reference voltage Vref1.

It is understood that the fluctuation of the voltage across the resonant capacitor Cr in two cycles before and after can be obtained by setting the difference unit 2231, and the fluctuation value can be changed to a positive number by setting the absolute value unit 2232, so as to be inputted to the threshold module 224 (comparing unit 2241) for comparison with a preset threshold/reference voltage (e.g., the first reference voltage Vref 1).

It can be understood that, taking the time T0 of the first period T1 and the time T5 of the second period T2 in fig. 2 as an example, when the difference between the voltages of the resonant capacitors Vcr at the same time points (i.e., the time T0 and the time T5) in two adjacent resonant periods (the first period T1 and the second period T2), that is, the difference between the voltage value Vcr1 of the resonant capacitor at the time T0 and the voltage value Vcr2 of the resonant capacitor at the time T5 (i.e., the difference between the first voltage value V1 and the second voltage value V2) exceeds a predetermined threshold, for example, the first reference voltage Vref1, it indicates that the voltage converting device 200 is in a resonant unbalanced state, and further, by turning off the first switching tube S1 and/or the second switching tube S2, the operation of the voltage converting device 200 is stopped, so as to avoid generating noise or causing device damage.

It can be understood that the control unit 221 outputs different switching signals (e.g., the first switching signal P1 and the second switching signal P2) at different time instants to control the sampling module 222 to sample the voltage across the resonant capacitor Cr at different time instants (e.g., the first time instant and the second time instant) to obtain the first voltage value V1 and the second voltage value V2. The threshold module 223 determines whether the fluctuation of the voltage across the resonant capacitor Cr meets a preset condition, and outputs a corresponding enable signal (e.g., a first enable signal E1) to turn off the first switch tube S1 and/or the second switch tube S2 by the control unit 221 when the fluctuation meets the preset condition, so as to prevent the voltage conversion device from being damaged due to the fact that the voltage conversion device continues to work in an unbalanced state.

Example two

Fig. 4 is a waveform diagram of the operation of the asymmetric half-bridge converting unit under an overcurrent condition according to an embodiment of the present application. Here, the asymmetric half-bridge converting unit may be the asymmetric half-bridge converting unit 100 shown in fig. 1A, or may be the asymmetric half-bridge converting unit 100a shown in fig. 1B. For convenience of description, the following description will take the asymmetric half-bridge converting unit 100 in fig. 1A as an example.

When the asymmetric half-bridge converting unit 100 is in an overcurrent state, for example, the output is in a short-circuit state, during the charging phase, the asymmetric half-bridge converting unit 100 is affected by the control loop, which may increase the exciting inductance current I _LM At this time, the on-time of the first switch tube S1 is also increased, so that the peak value of the resonant capacitor voltage Vcr is also increased during this period. Exciting inductor current I _LM The higher the peak value of (a), the larger the difference Δ Vcr between the peak value and the bottom value of the corresponding resonant capacitor voltage Vcr, without changing the input/output and excitation inductance Lm of the asymmetric half-bridge conversion unit 100. Therefore, the second embodiment provides a voltage conversion device, which can detect the ripple of the resonant capacitor voltage Vcr, for example, the difference Δ Vcr between the peak voltage Vpeak1 (or the voltage near the peak voltage Vpeak 1) and the valley voltage V _ vally1 (or the voltage near the valley voltage vpelk 1) in fig. 4, to determine whether the asymmetric half-bridge conversion unit 100 is in the overcurrent state.

In addition, it can be understood that when the asymmetric half-bridge converting unit 100 is in an overcurrent state, the asymmetric half-bridge converting unit 100 may be in an unbalanced state. Therefore, by monitoring whether the asymmetric half-bridge conversion unit 100 is in an overcurrent state, it is also possible to monitor whether the asymmetric half-bridge conversion unit 100 is in an unbalanced state.

Specifically, please refer to fig. 5, which is a schematic diagram of a voltage converting device 200a according to a second embodiment of the present application. In this embodiment, the voltage conversion device 200a includes a resonant conversion unit 210 and a control circuit 220a.

It is to be understood that, in the second embodiment, the resonant converting unit 210 and the sampling module 222 in the control circuit 220a are substantially the same as those in the first embodiment, and are not described herein again.

It is understood that the voltage conversion device 200a in the second embodiment is different from the voltage conversion device 200 in the first embodiment in the time when the control unit 221a outputs the first switching signal P1 and the second switching signal P2, the configuration of the operation module 223a and the threshold module 224a in the second processing module 2202.

Referring to fig. 5, in the second embodiment of the present application, the control unit 221a is configured to obtain the first voltage value V1 at a first time and obtain the second voltage value V2 at a second time, respectively. The first voltage value V1 and the second voltage value V2 are both used for representing voltages at two ends of the resonant capacitor Vcr.

Referring to fig. 4, in the second embodiment, the first time is a start point (time t 0) or an end point (time t 1) of a first dead time Td1, and the first dead time Td1 is a time from a time when the first switching tube S1 is turned off (i.e., vgs1 is at a low level) to a time when the second switching tube S2 is turned on (i.e., vgs2 is at a high level). The second time is the starting point (time t 2) or the end point (time t 3) of the second dead time Td2, and the second dead time Td2 is the time from the time when the second switch tube S2 is turned off (i.e., vgs2 is at low level) to the time when the first switch tube S1 is turned on (i.e., vgs1 is at high level). The first dead time Td1 and the second dead time Td2 are in one resonant period T0 of the voltage conversion device 200a. It is understood that, in the second embodiment, each resonant period includes a first dead time Td1 and a second dead time Td2.

It can be understood that, in the second embodiment, the first switch tube S1 is a main switch tube, and the second switch tube S2 is an auxiliary switch tube (see fig. 5). Taking a complete resonant period T0 in fig. 4 as an example, since the first switching tube S1 is turned on at the time T1, the voltage across the resonant capacitor Cr (i.e., the resonant capacitor voltage Vcr) gradually increases until the resonant capacitor voltage Vcr is already at a higher position and is near the peak value than at the time T0 when the first switching tube S1 is turned off at the time T1. During the first dead time Td1 from the turn-off of the first switching tube S1 to the turn-on of the second switching tube S2, the resonant capacitor voltage Vcr continues to increase closer to the peak value. Shortly after the second switching tube S2 is switched on, i.e. the field inductor current I _LM When the voltage Vcr changes from positive to negative, the resonant capacitor voltage Vcr reaches a peak value. Subsequently, the resonant capacitor voltage Vcr starts to drop, and when the second switching tube S2 is turned off, the resonant capacitor voltage Vcr is already at a lower position and is located near the valley. During the second dead time Td2 from the turning-off of the second switching tube S2 to the turning-on of the first switching tube S1, the resonant capacitor voltage Vcr continues to decrease until the first switching tube S1 reaches the valley value when turned on.

It can be understood that the voltages at the two ends of the resonant capacitor Cr collected at the start point or the end point of the first dead time Td1 and the second dead time Td2 are near the valley value and the peak value, so that the ripple voltage can be made as large as possible to reduce the error in the value comparison as possible.

In a possible implementation manner, the first time is when the first switching tube S1 is turned off, and the second time is when the first switching tube S1 is turned on. For another example, in another possible implementation manner, the first time is when the second switching tube S2 is turned on, and the second time is when the second switching tube S2 is turned off. For another example, in another possible implementation manner, the first time is when the first switching tube S1 is turned off, and the second time is when the second switching tube S2 is turned off. For another example, in another possible implementation manner, the first time is when the first switching tube S1 is turned on, and the second time is when the second switching tube S2 is turned on.

It can be understood that the acquisition timings of the first voltage value V1 and the second voltage value V2 can be accurately controlled and the error can be reduced by collecting the voltages at the two ends of the resonant capacitor Cr at the moment when the first switching tube S1 (or the second switching tube S2) is turned on or off.

Preferably, the first time is a time when the second switching tube S2 is turned on, and the second time is a time when the first switching tube S1 is turned on. Understandably, the exciting inductance current I _LM When the time of reaching the peak value is closer to the second switch tube S2 to be conducted, and the voltage at the two ends of the resonant capacitor Cr reaches the valley value at the same time when the first switch tube S1 is conducted. Therefore, the ripple voltage corresponding to the collected first voltage value V1 and the second voltage value V2 is larger at the two moments.

It is to be understood that the sequence of the first time and the second time is not limited in this embodiment. In one possible implementation manner, the voltage near the peak value of the resonant capacitor voltage Vcr is collected at the first time, and then the voltage at the valley value of the resonant capacitor voltage Vcr is collected at the second time. In another possible implementation manner, the valley voltage of the resonant capacitor voltage Vcr is collected at the second time, and then the voltage near the peak value of the resonant capacitor voltage Vcr is collected at the first time.

The sampling module 222 is configured to receive the first switch signal P1 and the second switch signal P2, collect voltages at two ends of the resonant capacitor Cr, output a first voltage value V1 based on the first switch signal P1, and output a second voltage value V2 based on the second switch signal P2.

The operation module 223a is configured to generate a ripple voltage (a second ripple voltage) according to the first voltage value V1 and the second voltage value V2.

In one possible implementation, the operation module 223a includes a difference unit 2231 and an absolute value unit 2232. The difference unit is used for receiving the first voltage value V1 and the second voltage value V2, and outputting a difference signal after the difference between the first voltage value V1 and the second voltage value V2. The absolute value unit 2232 is configured to take an absolute value of the difference signal and output a second ripple voltage.

In another possible implementation, the operation module 223a includes only the difference unit 2231, i.e., omits the absolute value unit 2232. It can be understood that the absolute value unit 2232 may be omitted because a difference signal obtained by subtracting the voltage (i.e., the first voltage value V1) collected in the valley stage from the voltage (i.e., the second voltage value V2) collected in the peak stage at the voltage across the resonant capacitor Cr is a positive value.

It can be understood that the fluctuation magnitude of the voltage across the resonant capacitor Cr between the peak value and the valley value can be obtained by the setting operation module 223 a.

The threshold module 224a is configured to determine that the voltage conversion device 200a is in a resonant unbalanced state and turn off the first switch tube S1 and/or the second switch tube S2 when the second ripple voltage meets a preset condition. Specifically, the threshold module 224a is configured to receive the second reference voltage Vref2 and the second ripple voltage, and output the second enable signal E2 to the control unit 221a when the second ripple voltage satisfies the preset condition. The preset condition is that the ratio of the second ripple voltage to the first voltage value V1, or the ratio of the second ripple voltage to the second voltage value V2 reaches a preset threshold (a second reference voltage Vref 2), and the second enable signal E2 is used for driving the control unit 221a to control the first switching tube S1 and/or the second switching tube S2 to be turned off.

It can be understood that by calculating the ratio of the second ripple voltage to the first voltage value V1 or the second voltage value V2 and comparing the values by the ratio, the influence caused by the output voltage change of the voltage conversion device 200a can be reduced to adapt to the voltage conversion device 200a with wide output range.

Referring to fig. 4, for example, assuming that the voltage converting device 200a does not have an overcurrent state at the time corresponding to the peak value Vpeak1, the peak value Vpeak1 is the peak value of the resonant capacitor voltage Vcr in the normal operating state, and the ratio of the difference Δ Vcr1 between the peak value Vpeak1 and the valley value V _ vally1 to the valley value V _ vally1 is used as a preset threshold, i.e., the second reference voltage Vref2. When the resonance imbalance (or the overcurrent state) is determined, the first voltage value V1 is acquired at a time corresponding to the valley value V _ vally2, the second voltage value V2 is acquired at a time corresponding to the peak value Vpeak2, and a ratio of a difference Δ VCr2 between the peak value Vpeak2 and the valley value V _ vally2 at this time is used as the second ripple voltage. The second ripple voltage (Δ VCr2/V _ vally 2) is compared with the second reference voltage Vref2 (Δ VCr1/V _ vally 1), and when the second ripple voltage reaches the second reference voltage Vref2, it indicates that the voltage converting device 200a has a resonance imbalance (or an overcurrent state).

It can be understood that in practical applications, the value of the second reference voltage Vref2 is slightly higher than the ratio (for example, Δ VCr1/V _ vally 1) obtained by the voltage conversion device 200a in the normal state, so as to prevent the voltage conversion device 200a from misjudging the overcurrent state.

In one possible implementation, the threshold module 224a includes a comparison unit 2241 and a ratio unit 2242. The ratio unit 2242 is configured to receive the second ripple voltage and the first voltage value V1, or receive the second ripple voltage and the second voltage value V2 (not shown), and obtain a ratio between the second ripple voltage and the first voltage value V1 or a ratio between the second ripple voltage and the second voltage value V2, so as to output a ratio signal. The comparing unit 2241 is configured to receive the second reference voltage Vref2 and the ratio signal, compare the ratio signal with the second reference voltage Vref2, and output a second enable signal E2 to the control unit 221a when the ratio signal reaches the second reference voltage Vref2. It is understood that the comparing unit 2241 may be, for example, a comparator, and the ratio unit 2242 may be, for example, a Divider (DIV) circuit.

It can be understood that, since the ratio unit 2242 outputs the second ripple voltage as a relative ratio to the resonant capacitor voltage Vcr (the first voltage value V1 or the second voltage value V2). Therefore, even when the voltage conversion device 200a regulates the output voltage Vout, the relative ratio does not change significantly, so that the possibility of erroneous determination of the overcurrent state can be reduced, and the voltage conversion device 200a can be more suitably used for a wide-range output.

It can be understood that the first voltage value V1 and the second voltage value V2 are obtained by collecting the voltages at the valley stage and the peak stage of the two ends of the resonant capacitor Cr, and then the second ripple voltage is obtained. Then, the resonance current I is indirectly judged through the relative ratio of the second ripple voltage to the first voltage value V1 or the second voltage value V2 _Lr The size of (2). When the relative ratio of the second ripple voltage to the first voltage value V1 or the second voltage value V2 is large enough, for example, larger than a preset threshold (for example, the second reference voltage Vref 2), the resonant current I is determined _Lr When the voltage conversion device 200a is in an overcurrent state, the first switch tube S1 and/or the second switch tube S2 are turned off to prevent the voltage conversion device 200a from being damaged due to the overcurrent state.

Referring to fig. 6, in another possible implementation manner, the second processing module 2202 further includes a counting module 225, and the threshold module 224a is configured to output an over-current signal N to the counting module 225 when a ratio of the second ripple voltage to the first voltage value V1 or the second voltage value V2 reaches a preset threshold (e.g., the second reference voltage Vref 2). The counting module 225 is configured to count the number of the over-current signals N in an accumulated manner, when the number of the over-current signals N accumulated within a preset period of time of the counting module 225 reaches a preset threshold number, the counting module 225 generates a second enable signal E2 to the control unit 221, and the second enable signal E2 is used to drive the control unit 221a to control the first switch tube S1 and/or the second switch tube S2 to be turned off.

It can be understood that, by setting the counting module 225 to count the overcurrent signal N in an accumulated manner, and generating the second enable signal E2 when the overcurrent signal N is accumulated for a certain number of times within a preset period of time, it can be avoided that the voltage conversion device 200a is determined to be in a resonance unbalanced (or overcurrent) state due to an occasional overcurrent signal N, and further, the possibility of misjudgment can be reduced.

It will be appreciated that in some other embodiments, the over-current signal N may be processed in other manners, for example, when the over-current signal N is generated for a plurality of consecutive resonance periods, it is determined that the voltage converting device 200a is in the unbalanced resonance (or over-current) state.

Example three:

referring to fig. 7, a schematic diagram of a voltage converting device 200b according to a third embodiment of the present application is shown. In this embodiment, the voltage conversion device 200b includes a resonant conversion unit 210 and a control circuit 220b.

It is understood that in the third embodiment, the resonant transformation unit 210 is substantially the same as the first or second embodiment, and is not described herein again.

It is to be understood that the voltage converting device 200b of the third embodiment is different from the voltage converting device 200 of the first embodiment in that the structure of the control circuit 220b of the third embodiment is different. Specifically, the control circuit 220b includes a control unit 221b, a first processing module 2201, and a second processing module 2202. The structure of the first processing module 2201 is the same as that of the processing module 2201 in the first embodiment, and is not described herein again. The structure of the second processing module 2202 is the same as the structure of the second processing module 2202 in the second embodiment, and is not described again here.

In this embodiment, the control unit 221b is configured to output the first switching signal P1 and the second switching signal P2 at a first time and a second time, respectively, where the first time and the second time are the same time of two adjacent resonant periods of the voltage conversion device 200 b. The control unit 221b is further configured to output a third switching signal P3 and a fourth switching signal P4 at a third time and a fourth time, respectively, where the third time is a start point or an end point of a first dead time, the fourth time is a start point or an end point of a second dead time, and the first dead time and the second dead time belong to the same resonance period.

The first processing module 2201 is configured to collect a first voltage value V1 and a second voltage value V2 based on the first switching signal P1 and the second switching signal P2, respectively, and generate a first ripple voltage after passing through the operation module 223, where the first ripple voltage is input to the threshold module 224 and then compared with the first reference voltage Vref1, and when the first ripple voltage reaches the first reference voltage Vref1, it is determined that the voltage conversion device 200c is in a resonance unbalanced state, and then the first enable signal E1 is output to the control unit 221b.

The second processing module 2202 is configured to collect a first voltage value V3 and a fourth voltage value V4 based on a third switching signal P3 and a fourth switching signal P4, generate a second ripple voltage after passing through the operation module 223, input the second ripple voltage to the threshold module 224, compare a ratio signal determined according to a ratio of the second ripple voltage to the third voltage value V3 or the fourth voltage value V4 with a second reference voltage Vref2, determine that the voltage conversion device 200c is in a resonance unbalanced state when the ratio signal reaches the second reference voltage Vref2, and output a second enable signal E2 to the control unit 221b.

The control unit 221b is further configured to turn off the first switch tube S1 and/or the second switch tube S2 when receiving the first enable signal E1 or the second enable signal E2.

It can be understood that by arranging the first processing module 2201 and the second processing module 2202, the resonance unbalanced state of the voltage conversion device 200b can be detected more comprehensively and accurately, and further, noise generation or device damage caused by the voltage conversion device 200b can be effectively avoided.

Example four:

referring to fig. 8, an embodiment of the present application further provides a method for controlling a voltage converting device, which is applicable to the voltage converting device 200/200a/200b of the above embodiment, and the method for controlling a voltage converting device is described in detail below by taking the application to the voltage converting device 200 as an example. As shown in fig. 8, the method of controlling the voltage converting device includes:

s11, respectively obtaining a first voltage value V1 at a first time and a second voltage value V2 at a second time. The first voltage value V1 and the second voltage value V2 are used for representing voltages at two ends of the resonant capacitor Vcr.

It can be understood that, as shown in fig. 3, the control circuit 220 may obtain the first voltage value V1 and the second voltage value V2 through the sampling module 222, and the specific working principle thereof may refer to fig. 3 and the related description thereof, which are not repeated herein.

And S12, obtaining ripple voltage according to the first voltage value V1 and the second voltage value V2.

It can be understood that, as shown in fig. 3, the control circuit 220 may calculate a voltage difference between the first voltage value V1 and the second voltage value V2 through the operation module 223 to obtain the first ripple voltage, and the specific working principle thereof may refer to fig. 3 and the related description thereof, which are not repeated herein.

And S13, when the ripple voltage meets a preset condition, determining that the voltage conversion device is in a resonance unbalanced state, and turning off the first switch tube S1 and/or the second switch tube S2.

It can be understood that, as shown in fig. 3, the control circuit 220 may turn off the first switching tube S1 and/or the second switching tube S2 through the threshold module 224 when the ripple voltage satisfies the preset condition.

It can be understood that the ripple voltage is obtained by obtaining the first voltage value V1 and the second voltage value V2, and obtaining the ripple voltage from the first voltage value V1 and the second voltage value V2. When the ripple voltage meets the preset condition, the voltage conversion device is determined to be in a resonance unbalanced state, and then the first switch tube S1 and/or the second switch tube S2 are turned off, so that the voltage conversion device 200/200a/200b is prevented from continuously working in the unbalanced state to cause damage.

Example five:

fig. 9 is a schematic structural diagram of a power supply apparatus 300 according to a fourth embodiment of the present application. The power supply apparatus 300 may supply power to the load 400. Load 400 may include, but is not limited to, a personal computer, a cell phone, a computer, a television display screen, and the like.

In one possible implementation, the power supply device 300 is an AC-DC (alternating current to direct current) conversion system. The power supply apparatus 300 includes an AC-DC conversion unit 310 and a DC-DC voltage conversion device 320. The AC-DC conversion unit 310 is configured to convert an alternating voltage into a direct voltage, and output the direct voltage to the voltage conversion unit 320. It is understood that the voltage converting device 320 in this embodiment may be any one of the voltage converting devices 200/200a/200b in the above embodiments, and will not be described herein again.

In another possible implementation, the power supply apparatus 300 may also be a DC-DC conversion system. Correspondingly, the power supply apparatus 300 includes a DC-DC voltage converting device 320 for converting a DC input voltage into a DC output voltage.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A voltage conversion device comprises a resonance conversion unit and a control circuit, wherein the resonance conversion unit comprises a resonance capacitor, a first switch tube and a second switch tube,

the control circuit is configured to:

acquiring a first voltage value at two ends of the resonance capacitor at a first moment and acquiring a second voltage value at two ends of the resonance capacitor at a second moment;

obtaining ripple voltage according to the first voltage value and the second voltage value; and

and when the ripple voltage meets a preset condition, determining that the voltage conversion device is in a resonance unbalanced state, and turning off the first switch tube and/or the second switch tube.

2.A voltage conversion arrangement as claimed in claim 1, characterized in that said control circuit comprises: the device comprises a control unit, a sampling module, an operation module and a threshold module;

the control unit is used for:

outputting a first switching signal at the first time and outputting a second switching signal at the second time;

turning off the first switching tube and/or the second switching tube when an enabling signal is received;

the sampling module is configured to:

receiving the first switching signal, collecting the voltage at two ends of the resonant capacitor, and outputting the first voltage value;

the sampling module receives the second switching signal, collects the voltage at two ends of the resonant capacitor and outputs a second voltage value;

the operation module is used for outputting the ripple voltage according to the first voltage value and the second voltage value;

the threshold module is used for determining that the voltage conversion device is in a resonance unbalanced state when the ripple voltage meets a preset condition, and outputting the enabling signal to the control unit.

3. A voltage conversion device as recited in claim 2, wherein said voltage conversion device includes a resonance period, and said first time and said second time are the same time of two adjacent resonance periods;

the preset condition is that the ripple voltage reaches a reference voltage.

4. A voltage conversion device as recited in claim 3,

the first moment is the moment when the first switching tube or the second switching tube is switched on or the moment when the first switching tube or the second switching tube is switched off in a first resonance period;

the second time is a time corresponding to the first time in a second resonance period, wherein the first resonance period and the second resonance period are two adjacent resonance periods.

5. A voltage conversion device as recited in claim 3 or 4,

the operation module comprises a difference unit and an absolute value unit, the difference unit is used for receiving the first voltage value and the second voltage value, performing difference and outputting a difference signal, and the absolute value unit is used for taking an absolute value of the difference signal and outputting the ripple voltage;

the threshold module comprises a comparison unit, and the comparison unit is used for receiving the reference voltage and the ripple voltage, comparing the reference voltage and the ripple voltage, and outputting the enable signal to the control unit when the ripple voltage reaches the reference voltage.

6. A voltage conversion arrangement as claimed in claim 2, characterized in that the voltage conversion arrangement comprises a resonance period, which resonance period comprises a first dead time and a second dead time, wherein,

the first time is the starting point or the end point of the first dead time, and the second time is the starting point or the end point of the second dead time;

the first dead time is the time from the turn-off moment of the first switch tube to the turn-on moment of the second switch tube, and the second dead time is the time from the turn-off moment of the second switch tube to the turn-on moment of the first switch tube;

the preset condition is that the ratio of the ripple voltage to the first voltage value reaches a reference voltage, or the ratio of the ripple voltage to the second voltage value reaches the reference voltage.

7. The voltage converter as claimed in claim 6, wherein the first switch is a main switch, the first time is when a second switch is turned on, and the second time is when the first switch is turned on.

8. A voltage conversion device as recited in claim 6 or 7,

the threshold module comprises a ratio unit and a comparison unit;

the ratio unit is configured to receive the ripple voltage and the first voltage value, or receive the ripple voltage and the second voltage value, and obtain a ratio of the ripple voltage to the first voltage value or a ratio of the ripple voltage to the second voltage value, so as to output a ratio signal;

the comparison unit is used for receiving the reference voltage and the ratio signal, comparing the reference voltage and the ratio signal, and outputting the enable signal to the control unit when the ratio signal reaches the reference voltage.

9. A voltage conversion device as claimed in any one of claims 2 to 8,

the sampling module comprises a first switch, a second switch, a first sampling and holding unit and a second sampling and holding unit;

a first end of the first switch is connected to two ends of the resonant capacitor, a second end of the first switch is connected to the first sample-and-hold unit, and a third end of the first switch is connected to the control unit;

a first end of the second switch is connected to two ends of the resonant capacitor, a second end of the second switch is connected to the second sample-and-hold unit, and a third end of the second switch is connected to the control unit;

the first sample-and-hold unit is used for outputting the first voltage value when the first switch is controlled to be closed by the first switch signal;

the second sample-and-hold unit is used for outputting the second voltage value when the second switch is controlled to be closed by the second switch signal.

10. A control method of a voltage conversion device comprises a resonance conversion unit and a control circuit, wherein the resonance conversion unit comprises a resonance capacitor, a first switch tube and a second switch tube, and the method is characterized by comprising the following steps:

acquiring a first voltage value at two ends of the resonant capacitor at a first moment and acquiring a second voltage value at two ends of the resonant capacitor at a second moment;

11. The method according to claim 10, wherein said voltage conversion means includes a resonance period, and said first time and said second time are the same time of two adjacent resonance periods;

the preset condition is that the ripple voltage reaches a reference voltage.

12. The method of claim 11,

13. The method of claim 11, wherein the obtaining a ripple voltage according to the first voltage value and the second voltage value comprises:

outputting a difference signal after the first voltage value and the second voltage value are differed;

the ripple voltage is output after the absolute value of the difference signal is taken; when the ripple voltage meets a preset condition, determining that the voltage conversion device is in a resonance unbalanced state, and turning off the first switch tube and/or the second switch tube, including:

comparing the reference voltage with the ripple voltage, determining that the voltage conversion device is in a resonance unbalanced state when the ripple voltage reaches the reference voltage, and outputting an enable signal;

and turning off the first switching tube and/or the second switching tube according to the enabling signal.

14. The method of claim 10, wherein the voltage converter comprises a resonant period, and the resonant period comprises a first dead time and a second dead time, wherein the first time is a start point or an end point of the first dead time, the second time is a start point or an end point of the second dead time, the first dead time is a time from a turn-off time of the first switch tube to a turn-on time of the second switch tube, and the second dead time is a time from a turn-off time of the second switch tube to a turn-on time of the first switch tube;

15. The method of claim 14, wherein the first switch tube is a main switch tube, the first time is a time when the second switch tube is turned on, and the second time is a time when the first switch tube is turned on.

16. The method according to claim 14 or 15, wherein the obtaining a ripple voltage according to the first voltage value and the second voltage value comprises:

the ripple voltage is output after the absolute value of the difference signal is taken;

when the ripple voltage meets a preset condition, determining that the voltage conversion device is in a resonance unbalanced state, and turning off the first switch tube and/or the second switch tube, including:

comparing a reference voltage with a ratio signal, and when the ratio signal reaches the reference voltage, determining that the voltage conversion device is in a resonance unbalanced state, and outputting an enable signal, wherein the ratio signal is the ratio of the ripple voltage to the first voltage value or the ratio of the ripple voltage to the second voltage value;

17. A power supply apparatus characterized by comprising:

an AC-DC voltage conversion unit for converting an AC voltage into a DC input voltage; and

the voltage conversion device is used for receiving the direct-current input voltage output by the AC-DC voltage conversion unit, performing direct-current voltage conversion and outputting direct-current output voltage; the voltage conversion device comprises a resonance conversion unit and a control circuit, wherein the resonance conversion unit comprises a resonance capacitor, a first switch tube and a second switch tube, and the control circuit is used for: acquiring a first voltage value at two ends of the resonance capacitor at a first moment and acquiring a second voltage value at two ends of the resonance capacitor at a second moment; obtaining ripple voltage according to the first voltage value and the second voltage value; and when the ripple voltage meets a preset condition, determining that the voltage conversion device is in a resonance unbalanced state, and turning off the first switch tube and/or the second switch tube.