CN107437892B

CN107437892B - Power converter and control method thereof

Info

Publication number: CN107437892B
Application number: CN201710639766.8A
Authority: CN
Inventors: 郭丰
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Digital Power Technologies Co Ltd
Priority date: 2017-07-31
Filing date: 2017-07-31
Publication date: 2020-04-03
Anticipated expiration: 2037-07-31
Also published as: CN107437892A

Abstract

The embodiment of the application discloses a power converter and a control method thereof, wherein the power converter comprises a primary circuit, a secondary circuit, a resonant circuit and a drive control circuit, the primary circuit comprises a primary switch tube and a voltage regulating circuit, the primary switch tube forms a first bridge arm and a second bridge arm, the secondary circuit comprises a secondary switch tube, the primary circuit is connected with the input end of the resonant circuit, and the secondary circuit is connected with the output end of the resonant circuit; the input end of the voltage regulating circuit is connected with an input power supply of the power converter, the output end of the voltage regulating circuit is connected with the second bridge arm, and the voltage regulating circuit is used for regulating the voltage of the second bridge arm in the starting process of the power converter; the driving control circuit is respectively connected with the primary side circuit and the secondary side circuit and is used for controlling the conduction state of the primary side switching tube and the secondary side switching tube. By adopting the embodiment of the application, the impact current in the starting process of the power converter can be effectively reduced, and the stability of the power converter during starting is improved.

Description

Power converter and control method thereof

Technical Field

The present disclosure relates to power supply technologies, and particularly to a power converter and a control method thereof.

Background

When a power converter (such as a dual-inductor single-capacitor LLC circuit) is started, since the output of the power converter at the start moment is about 0, if the voltage ratio of the input power of the power converter is high, the inrush current (such as the resonant current) generated at the start moment is large, which may cause circuit burnout. When suppressing the inrush current, a currently common scheme is to use a higher operating frequency and a smaller duty ratio for a Pulse Width Modulation (PWM) wave used when the power converter is started, so that the switch can be turned off before the inrush current reaches the peak value. However, due to the process limitation of the switching tube and the process limitation of the driving chip, the frequency increase is easily limited, and when the frequency increase is easily limited, the duty ratio cannot be too small, otherwise the power converter cannot provide enough energy to complete the charging of the post-stage capacitor, or cannot start with load. Therefore, how to reduce the inrush current when the power converter is started has become an urgent problem to be solved.

Disclosure of Invention

The embodiment of the application discloses a power converter and a control method thereof, which can effectively reduce the impact current in the starting process of the power converter and improve the stability of the power converter during starting.

A first aspect of embodiments of the present application provides a power converter, including:

the primary circuit comprises a primary switch tube and a voltage regulating circuit, the primary switch tube forms a first bridge arm and a second bridge arm, and the secondary circuit comprises a secondary switch tube, wherein:

the primary side circuit is connected with the input end of the resonance circuit, and the secondary side circuit is connected with the output end of the resonance circuit.

The input end of the voltage regulating circuit is connected with the input power supply of the power converter, the output end of the voltage regulating circuit is connected with the second bridge arm, and the voltage regulating circuit is used for regulating the voltage of the second bridge arm in the starting process of the power converter.

The driving control circuit is respectively connected with the primary side circuit and the secondary side circuit and used for generating driving control signals of the primary side circuit and the secondary side circuit, and the driving control signals are used for controlling the conduction states of the primary side switch tube and the secondary side switch tube.

Optionally, the resonant circuit includes a resonant capacitor and a transformer.

The midpoint of the first bridge arm in the primary side circuit is connected with the midpoint of the second bridge arm in the primary side circuit through a series circuit formed by the resonance capacitor and the primary coil of the transformer.

Optionally, the primary side switching tube includes a first switching tube, a second switching tube, a third switching tube and a fourth switching tube connected in a full-bridge manner, the first switching tube and the second switching tube form the first bridge arm, and the third switching tube and the fourth switching tube form the second bridge arm.

The first switch tube is connected with the input power supply, the third switch tube is connected with the output end of the voltage regulating circuit, and the second switch tube and the fourth switch tube are connected with the grounding point of the power converter.

The secondary side switching tube comprises a fifth switching tube, a sixth switching tube, a seventh switching tube and an eighth switching tube which are connected in a full-bridge mode, the fifth switching tube and the sixth switching tube form a third bridge arm of the secondary side circuit, and the seventh switching tube and the eighth switching tube form a fourth bridge arm of the secondary side circuit.

And the middle point of the third bridge arm is connected with the middle point of the fourth bridge arm through a secondary coil of the transformer.

Optionally, the voltage regulating circuit is specifically configured to regulate the voltage of the second bridge arm to a first target voltage value, the voltage of the input power supply, the first target voltage value, and a second target voltage value in sequence in the starting process of the power converter.

The first target voltage value is smaller than or equal to a minimum value, and the second target voltage value is determined according to the target output voltage of the power converter.

Optionally, the driving control circuit is specifically configured to generate a first driving control signal when the voltage regulating circuit regulates the voltage of the second bridge arm to the first target voltage value, where the first driving control signal is used to control the first switching tube to be turned off, the second switching tube is turned on, and the third switching tube and the fourth switching tube both work in a Pulse Width Modulation (PWM) state.

The driving control circuit is specifically configured to generate a second driving control signal when the voltage regulating circuit regulates the voltage of the second bridge arm to the voltage of the input power supply, where the second driving control signal is the same as the first driving control signal.

The driving control circuit is specifically configured to generate a third driving control signal when the voltage regulating circuit regulates the voltage of the second bridge arm to the first target voltage value again, where the third driving control signal is used to control the first switching tube and the second switching tube to work in a PWM state, the third switching tube is turned on, and the fourth switching tube is turned off.

The driving control circuit is specifically configured to generate a fourth driving control signal when the voltage regulating circuit regulates the voltage of the second bridge arm to the second target voltage value, where the fourth driving control signal is used to control the first switching tube, the second switching tube, the third switching tube, and the fourth switching tube to all work in a PWM state.

Optionally, the driving control circuit is specifically configured to generate a first driving control signal when the voltage regulating circuit regulates the voltage of the second bridge arm to the first target voltage value, where the first driving control signal is used to control the first switching tube to be turned off, the second switching tube is turned on, and the third switching tube and the fourth switching tube both work in a PWM state.

The driving control circuit is specifically configured to generate a fifth driving control signal when the voltage regulating circuit regulates the voltage of the second bridge arm to the first target voltage value again, the fifth driving control signal is used to control the first switching tube, the second switching tube, the third switching tube and the fourth switching tube to be all turned off, and generate a sixth driving control signal when the voltage regulating circuit regulates the voltage of the second bridge arm to the first target voltage value, and the sixth driving control signal is used to control the first switching tube, the second switching tube, the third switching tube and the fourth switching tube to all work in a PWM state.

Wherein the sixth drive control signal and the fourth drive control signal are different in frequency and duty cycle.

The driving control circuit is specifically configured to generate a fifth driving control signal when the voltage regulating circuit regulates the voltage of the second bridge arm to the first target voltage value again, where the fifth driving control signal is used to control the first switching tube, the second switching tube, the third switching tube, and the fourth switching tube to be turned off.

Optionally, the conduction state of the secondary side switching tube is correspondingly the same as the conduction state of the switching tube in the primary side switching tube in the PWM working state.

Optionally, the primary circuit further includes a first filter capacitor and a second filter capacitor.

The first filter capacitor is located between the input power supply and the first bridge arm, and the first filter capacitor is connected with the first bridge arm in parallel.

The second filter capacitor is located between the output end of the voltage regulating circuit and the second bridge arm, and the second filter capacitor is connected with the second bridge arm in parallel.

Optionally, the secondary side circuit further includes a third filter capacitor.

The third filter capacitor is located at the output end of the power converter, and the third filter capacitor is connected with the third bridge arm and the fourth bridge arm in parallel.

Optionally, the voltage regulating circuit is a buck circuit or a buck boost circuit.

A second aspect of the embodiments of the present application provides a control method for a power converter, where the power converter includes a primary circuit, a secondary circuit, a resonant circuit, and a driving control circuit, the primary circuit includes a primary switching tube and a voltage regulating circuit, the primary switching tube forms a first bridge arm and a second bridge arm, the secondary circuit includes a secondary switching tube, and the method includes:

and in the starting process of the power converter, controlling the voltage regulating circuit to regulate the output voltage so as to regulate the voltage of the second bridge arm.

And controlling the drive control circuit to generate drive control signals of the primary side circuit and the secondary side circuit according to the regulation of the voltage of the second bridge arm.

And controlling the conduction state of the primary side switch tube and the secondary side switch tube by using the driving control signal.

Optionally, in the starting process of the power converter, controlling the voltage regulating circuit to regulate the output voltage so as to regulate the voltage of the second bridge arm includes:

and in the starting process of the power converter, controlling the voltage regulating circuit to regulate the output voltage, and regulating the voltage of the second bridge arm into a first target voltage value, the voltage of the input power supply, the first target voltage value and a second target voltage value in sequence.

Optionally, the primary side switching tube includes a first switching tube, a second switching tube, a third switching tube and a fourth switching tube connected in a full-bridge manner, the secondary side switching tube includes a fifth switching tube, a sixth switching tube, a seventh switching tube and an eighth switching tube connected in a full-bridge manner, and the driving control circuit is controlled to generate the driving control signals of the primary side circuit and the secondary side circuit according to the adjustment of the voltage of the second bridge arm, including:

when the voltage of the second bridge arm is adjusted to the first target voltage value, the driving control circuit is controlled to generate a first driving control signal, the first driving control signal is used for controlling the first switching tube to be turned off, the second switching tube is turned on, and the third switching tube and the fourth switching tube work in a PWM state.

And when the voltage of the second bridge arm is adjusted to the voltage of the input power supply, controlling the drive control circuit to generate a second drive control signal, wherein the second drive control signal is the same as the first drive control signal.

When the voltage of the second bridge arm is adjusted to the first target voltage value again, the driving control circuit is controlled to generate a third driving control signal, the third driving control signal is used for controlling the first switching tube and the second switching tube to work in a PWM state, the third switching tube is turned on, and the fourth switching tube is turned off.

And when the voltage of the second bridge arm is adjusted to the second target voltage value, controlling the drive control circuit to generate a fourth drive control signal, wherein the fourth drive control signal is used for controlling the first switching tube, the second switching tube, the third switching tube and the fourth switching tube to work in a PWM (pulse width modulation) state.

When the voltage of the second bridge arm is adjusted to the first target voltage value again, the drive control circuit is controlled to generate a fifth drive control signal, the fifth drive control signal is used for controlling the first switch tube, the second switch tube, the third switch tube and the fourth switch tube to be turned off, and when the voltage of the second bridge arm is adjusted to the first target voltage value, the drive control circuit is controlled to generate a sixth drive control signal, and the sixth drive control signal is used for controlling the first switch tube, the second switch tube, the third switch tube and the fourth switch tube to work in a PWM state.

And when the voltage of the second bridge arm is adjusted to the first target voltage value again, controlling the drive control circuit to generate a fifth drive control signal, wherein the fifth drive control signal is used for controlling the first switching tube, the second switching tube, the third switching tube and the fourth switching tube to be turned off.

A third aspect of embodiments of the present application provides a computer-readable storage medium having stored therein instructions, which, when executed on a computer, cause the computer to perform the method of the second aspect.

A fourth aspect of embodiments of the present application provides a computer program product comprising instructions which, when run on a computer, cause the computer to perform the method of the second aspect.

In the embodiment of the application, the power converter comprises a primary circuit, a secondary circuit, a resonant circuit and a driving control circuit, wherein the primary circuit comprises a primary switching tube and a voltage regulating circuit, the primary switching tube forms a first bridge arm and a second bridge arm, the secondary circuit comprises a secondary switching tube, the primary circuit is connected with the input end of the resonant circuit, and the secondary circuit is connected with the output end of the resonant circuit; the input end of the voltage regulating circuit is connected with an input power supply of the power converter, the output end of the voltage regulating circuit is connected with the second bridge arm, and the voltage regulating circuit is used for regulating the voltage of the second bridge arm in the starting process of the power converter; the driving control circuit is respectively connected with the primary side circuit and the secondary side circuit and used for generating driving control signals, and the driving control signals are used for controlling the conduction states of the primary side switching tube and the secondary side switching tube, so that the impact current in the starting process of the power converter can be effectively reduced, and the stability of the power converter during starting is improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments or the background art of the present application, the drawings required to be used in the embodiments or the background art of the present application will be described below.

Fig. 1 is a schematic structural diagram of a power converter disclosed in an embodiment of the present application;

FIG. 2a is a schematic diagram of a voltage regulation disclosed in an embodiment of the present application;

FIG. 2b is a schematic diagram of a driving control signal disclosed in an embodiment of the present application;

FIG. 2c is a schematic diagram of another driving control signal disclosed in the embodiments of the present application;

FIG. 2d is a schematic diagram of another driving control signal disclosed in the embodiments of the present application;

FIG. 2e is a schematic diagram of another driving control signal disclosed in the embodiments of the present application;

FIG. 2f is a schematic diagram of another driving control signal disclosed in the embodiments of the present application;

fig. 3 is a flowchart illustrating a control method of a power converter according to an embodiment of the present application.

Detailed Description

The embodiments of the present application will be described below with reference to the drawings.

Please refer to fig. 1, which is a schematic structural diagram of a power converter according to an embodiment of the present disclosure. The power converter described in this embodiment includes: former limit circuit, secondary circuit, resonant circuit and drive control circuit, wherein:

the primary circuit comprises a primary switch tube and an additional voltage regulating circuit, and the primary switch tube forms a first bridge arm and a second bridge arm.

The primary side switching tube comprises a first switching tube Q1, a second switching tube Q2, a third switching tube Q3 and a fourth switching tube Q4 which are connected in a full-bridge mode, the first switching tube Q1 and the second switching tube Q2 form a first bridge arm, and the third switching tube Q3 and the fourth switching tube Q4 form a second bridge arm.

The first switch tube Q1 is connected to the input power Vin of the power converter, the third switch tube Q3 is connected to the output end of the voltage regulating circuit, and the second switch tube Q2 and the fourth switch tube Q4 are connected to the grounding point of the power converter.

The secondary side circuit comprises a secondary side switching tube.

The secondary side switching tube comprises a fifth switching tube Q5, a sixth switching tube Q6, a seventh switching tube Q7 and an eighth switching tube Q8 which are connected in a full-bridge mode, the fifth switching tube Q5 and the sixth switching tube Q6 form a third bridge arm of the secondary side circuit, and the seventh switching tube Q7 and the eighth switching tube Q8 form a fourth bridge arm of the secondary side circuit.

The resonance circuit comprises a resonance capacitor Cr and a transformer T, and the turn ratio of the transformer T is set to be N.

It should be noted that the resonant circuit may further include a resonant inductor, and in fig. 1, the resonant inductor is replaced by a leakage inductor of the transformer T.

The midpoint of the first bridge arm in the primary circuit is connected with the midpoint of the second bridge arm in the primary circuit through a series circuit consisting of a resonant capacitor Cr and a primary coil of a transformer T.

The middle point of the third bridge arm in the secondary side circuit is connected with the middle point of the fourth bridge arm in the secondary side circuit through the secondary coil of the transformer T.

The input end of the voltage regulating circuit is connected with an input power Vin of the power converter, the output end of the voltage regulating circuit is connected with the second bridge arm, and the voltage regulating circuit is used for regulating the voltage Vm of the second bridge arm in the starting process of the power converter.

The driving control circuit is respectively connected with the primary side circuit and the secondary side circuit and is used for generating driving control signals of the primary side circuit and the secondary side circuit, and the driving control signals are used for controlling the conduction states of the primary side switch tube (namely, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4) and the secondary side switch tube (namely, the fifth switch tube Q5, the sixth switch tube Q6, the seventh switch tube Q7 and the eighth switch tube Q8).

The conduction state of the secondary side switching tube is correspondingly the same as the conduction state of the switching tube in the PWM working state in the primary side switching tube. Specifically, the conduction states of the sixth switching tube Q6 and the seventh switching tube Q7 may be the same as the conduction states of the second switching tube Q2 and/or the third switching tube Q3 in the PWM operating state, and the conduction states of the fifth switching tube Q5 and the eighth switching tube Q8 may be the same as the conduction states of the first switching tube Q1 and/or the fourth switching tube Q4 in the PWM operating state.

It should be noted that the driving control circuit may also be specifically divided into two driving control circuits, such as a primary side driving control circuit and a secondary side driving control circuit. The primary side driving control circuit is connected with the primary side circuit and used for generating a driving control signal of the primary side circuit, and the driving control signal is used for controlling the conduction state of a primary side switching tube (namely a first switching tube Q1, a second switching tube Q2, a third switching tube Q3 and a fourth switching tube Q4); the secondary side driving control circuit is connected with the secondary side circuit and used for generating a driving control signal of the secondary side circuit according to a driving control signal generated by the primary side driving control circuit, and the driving control signal is used for controlling the conducting state of the secondary side switching tube (namely, a fifth switching tube Q5, a sixth switching tube Q6, a seventh switching tube Q7 and an eighth switching tube Q8).

In some possible embodiments, the primary circuit further includes a first filter capacitor Cin1 and a second filter capacitor Cin2, the first filter capacitor Cin1 is located between the input power Vin and the first leg, and the first filter capacitor Cin1 is connected in parallel with the first leg. The second filter capacitor Cin2 is located between the output end of the voltage regulating circuit and the second bridge arm, and the second filter capacitor Cin2 is connected with the second bridge arm in parallel.

In some possible embodiments, the secondary side circuit further includes a third filter capacitor Co, where the third filter capacitor Co is located at the output end of the power converter, and the third filter capacitor Co is connected in parallel with the third bridge arm and the fourth bridge arm.

In some possible embodiments, the voltage regulating circuit may be a buck circuit or a buck boost circuit.

In some possible embodiments, the primary side switch tube and the secondary side switch tube may be Metal Oxide Semiconductor (MOS) or diodes, etc.

In some possible embodiments, the power converter may be a dual-inductor single-capacitor LLC circuit.

In a specific implementation, the voltage regulating circuit is configured to regulate the voltage Vm of the second bridge arm to a first target voltage value, the voltage Vin of the input power supply, the first target voltage value, and a second target voltage value in sequence in a starting process of the power converter.

The first target voltage value is less than or equal to a minimum value, that is, the voltage Vm of the second bridge arm is adjusted to the first target voltage value, where the voltage Vm of the second bridge arm is adjusted to 0, or a minimum value close to 0. The second target voltage value is determined according to a target output voltage of the power converter.

In the starting process of the power converter, according to the adjustment of the voltage regulating circuit, the change of the voltage Vm of the second bridge arm and the change of the output voltage Vo of the power converter can be as shown in fig. 2a, and the starting process of the power converter in the application can be divided into four stages.

In some possible embodiments, the four phases of the starting process of the power converter can be specifically realized as the following one:

in the first stage step1, the start preparation stage of the power converter, the voltage regulator circuit regulates the voltage Vm of the second leg to a first target voltage value (i.e., 0 or a minimum value close to 0).

And a driving control circuit, configured to generate a first driving control signal when the voltage Vm of the second bridge arm is adjusted to the first target voltage value by the voltage adjusting circuit, as shown in fig. 2b, in the first driving control signal, a driving control signal corresponding to the first switching tube Q1 is at a low level, a driving control signal corresponding to the second switching tube Q2 is at a high level, driving control signals corresponding to the third switching tube Q3 and the fourth switching tube Q4 are Pulse Width Modulation (PWM) waves, and driving control signals corresponding to the third switching tube Q3 and the fourth switching tube Q4 are complementary, so that the first driving control signal may be used to control the first switching tube Q1 to be turned off, the second switching tube Q2 to be turned on, and the third switching tube Q3 and the fourth switching tube Q4 both work in a PWM state. The conduction state of the secondary side switching tube is the same as the conduction state of the switching tube in the primary side switching tube in the PWM working state, specifically, the sixth switching tube Q6 and the seventh switching tube Q7 perform half-bridge synchronous rectification according to the PWM wave corresponding to the third switching tube Q3, and the fifth switching tube Q5 and the eighth switching tube Q8 perform half-bridge synchronous rectification according to the PWM wave corresponding to the fourth switching tube Q4.

Wherein the peak current I of the resonant current is about

Lr is the resonant inductance of the resonant circuit, which in this application is replaced by the leakage inductance of the transformer T. For the sake of calculation, it is assumed in this application that the turns ratio N of the transformer T is 1, i.e. the gain of the power converter is 1,

of course, the same applies to scenarios where the gain of the power converter is not 1. Since the voltage Vm of the second bridge arm and the output voltage Vo of the power converter are both close to 0, the resonant circuit does not generate a large resonant current in this stage.

In the second stage step2, the voltage-controlled bridge arm (i.e., the second bridge arm) in the primary circuit is used to boost the output voltage Vo of the power converter, and the voltage regulating circuit slowly regulates the voltage Vm of the second bridge arm from the first target voltage value in the first stage step1 to the voltage of the input power Vin.

And a drive control circuit, configured to generate a second drive control signal when the voltage regulator circuit regulates the voltage Vm of the second bridge arm from the first target voltage value to the voltage of the input power Vin (or a voltage close to the voltage of the input power Vin), where the second drive control signal is the same as the first drive control signal, and in the second drive control signal, as shown in fig. 2b, the drive control signal corresponding to the first switch tube Q1 is at a low level, the drive control signal corresponding to the second switch tube Q2 is at a high level, and the drive control signals corresponding to the third switch tube Q3 and the fourth switch tube Q4 are PWM waves, so that the first switch tube Q1 is kept off, the second switch tube Q2 is kept on, and the third switch tube Q3 and the fourth switch tube Q4 are both kept in a PWM state. Similarly, the conduction state of the secondary side switching tube is the same as the conduction state of the switching tube in the PWM working state in the primary side switching tube, specifically, the sixth switching tube Q6 and the seventh switching tube Q7 perform half-bridge synchronous rectification according to the PWM wave corresponding to the third switching tube Q3, and the fifth switching tube Q5 and the eighth switching tube Q8 perform half-bridge synchronous rectification according to the PWM wave corresponding to the fourth switching tube Q4.

Wherein the output voltage of the power converter

Vo will slowly rise to

(or close to)

A voltage of). The voltage Vm of the second bridge arm and the output voltage Vo of the power converter rise synchronously, and the resonant circuit does not generate a large resonant current in the current stage.

In the third stage step3, the voltage direction of the resonant capacitor Cr is adjusted by using the voltage-controlled bridge arm (i.e., the second bridge arm) in the primary circuit, and the voltage regulating circuit regulates the voltage Vm of the second bridge arm from the voltage of the input power Vin to the first target voltage value, i.e., regulates the voltage Vm of the second bridge arm to 0 again or to a minimum value close to 0.

And a driving control circuit, configured to generate a third driving control signal when the voltage regulator circuit regulates the voltage Vm of the second bridge arm from the voltage of the input power Vin to the first target voltage value, as shown in fig. 2c, in the third driving control signal, the driving control signals corresponding to the first switching tube Q1 and the second switching tube Q2 are PWM waves, the driving control signal corresponding to the third switching tube Q3 is at a high level, the driving control signal corresponding to the fourth switching tube Q4 is at a low level, and the driving control signals corresponding to the first switching tube Q1 and the second switching tube Q2 are complementary, so that the third driving control signal may be used to control the first switching tube Q1 and the second switching tube Q2 to operate in a PWM state, the third switching tube Q3 is turned on, and the fourth switching tube Q4 is turned off. Similarly, the conduction state of the secondary side switching tube is the same as the conduction state of the switching tube in the PWM working state in the primary side switching tube, specifically, the fifth switching tube Q5 and the eighth switching tube Q8 perform half-bridge synchronous rectification according to the PWM wave corresponding to the first switching tube Q1, and the sixth switching tube Q6 and the seventh switching tube Q7 perform half-bridge synchronous rectification according to the PWM wave corresponding to the second switching tube Q2.

Wherein the voltage Vm of the second bridge arm is slowly adjusted to 0 or a minimum value close to 0, the output voltage Vo of the power converter is kept unchanged and is always equal to

Voltage on the resonant capacitor Cr will be

Gradually become

Since the voltage changes slowly, the resonant circuit will not generate a large resonant current in this stage.

In the fourth stage step4, the output voltage Vo of the power converter is raised to the target output voltage in a full-bridge manner, and the voltage regulating circuit slowly regulates the voltage Vm of the second bridge arm from the first target voltage value to the second target voltage value, so that the output voltage Vo of the power converter reaches the target output voltage.

And a drive control circuit for generating a fourth drive control signal when the voltage regulator circuit regulates the voltage Vm of the second arm from the first target voltage value to the second target voltage value, wherein, as shown in fig. 2d, in the fourth drive control signal, the drive control signals corresponding to the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 are all PWM waves, the drive control signals corresponding to the first switching tube Q1 and the second switching tube Q2 are complementary, the drive control signal corresponding to the third switching tube Q3 is the same as the drive control signal corresponding to the second switching tube Q2, the drive control signal corresponding to the fourth switching tube Q4 is the same as the drive control signal corresponding to the first switching tube Q1, and the fourth drive control signal is used to control the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 to be in a PWM state. Similarly, the fifth switch Q5, the sixth switch Q6, the seventh switch Q7 and the eighth switch Q8 of the secondary switch are all operated in the PWM state to perform full-bridge synchronous rectification, wherein the driving control signals corresponding to the sixth switch Q6 and the seventh switch Q7 are the same as the driving control signals corresponding to the second switch Q2 (or the third switch Q3), and the driving control signals corresponding to the fifth switch Q5 and the eighth switch Q8 are the same as the driving control signals corresponding to the first switch Q1 (or the fourth switch Q4).

The voltage Vm of the second bridge arm is slowly increased to the second target voltage value, the voltage drop on the resonant circuit is about 0, and the resonant circuit cannot generate a large resonant current in this stage.

So far, power converter's output voltage Vo promotes the target output voltage, and power converter accomplishes the start-up process, and resonant circuit can not produce very big resonant current (promptly impact current) in whole start-up process, has guaranteed the stability when power converter starts.

In some possible embodiments, the four phases of the starting process of the power converter can be specifically implemented as the following two modes:

the first stage step1 is the same as in the first embodiment, and will not be described again.

The second stage step2 is the same as in the first mode, and is not described in detail.

In the third stage step3, the voltage direction of the resonant capacitor Cr is adjusted by using the voltage-controlled bridge arm (i.e., the second bridge arm) in the primary circuit, and the voltage regulating circuit quickly regulates the voltage Vm of the second bridge arm from the voltage of the input power Vin to the first target voltage value, i.e., regulates the voltage Vm of the second bridge arm to 0 again or to a minimum value close to 0.

And a drive control circuit, configured to generate a fifth drive control signal when the voltage regulator circuit regulates the voltage Vm of the second bridge arm from the voltage of the input power Vin to the first target voltage value, as shown in a left portion of a dotted line in fig. 2e, in the fifth drive control signal, the drive control signals corresponding to the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, and the fourth switch tube Q4 are all at a low level, and the fifth drive control signal is used to control the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, and the fourth switch tube Q4 to be turned off. Similarly, the fifth switch tube Q5, the sixth switch tube Q6, the seventh switch tube Q7 and the eighth switch tube Q8 in the secondary switch tube are all turned off.

The drive control circuit is also used for generating a sixth drive control signal when the voltage regulation circuit regulates the voltage Vm of the second bridge arm to be the first target voltage value, as shown in the right portion of the dotted line in fig. 2e, in the sixth driving control signal, the driving control signals corresponding to the first switch Q1, the second switch Q2, the third switch Q3 and the fourth switch Q4 are all PWM waves with high frequency and small duty ratio, the driving control signals corresponding to the first switch Q1 and the second switch Q2 are complementary, the driving control signal corresponding to the third switch Q3 is the same as the driving control signal corresponding to the second switch Q2, the driving control signal corresponding to the fourth switch Q4 is the same as the driving control signal corresponding to the first switch Q1, the sixth driving control signal can be used to control the first switch Q1, the second switch Q2, the third switch Q3 and the fourth switch Q4 to operate in the PWM state. Similarly, the fifth switch Q5, the sixth switch Q6, the seventh switch Q7 and the eighth switch Q8 of the secondary switch are all operated in the PWM state to perform full-bridge synchronous rectification, wherein the driving control signals corresponding to the sixth switch Q6 and the seventh switch Q7 are the same as the driving control signals corresponding to the second switch Q2 (or the third switch Q3), and the driving control signals corresponding to the fifth switch Q5 and the eighth switch Q8 are the same as the driving control signals corresponding to the first switch Q1 (or the fourth switch Q4).

When the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 are turned off, the output voltage Vo of the power converter drops at a certain rate under the traction of the load R, so that the voltage regulation circuit adjusts the voltage Vm of the second bridge arm to the first target voltage value as quickly as possible on the premise of meeting the current safety requirement of the voltage regulation circuit in order to avoid excessive drop. Then, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 are all controlled to work in the PWM state by a PWM wave with a frequency as high as possible and a duty ratio small enough, so that the voltage on the resonant capacitor Cr is controlled to be changed from the voltage on the resonant capacitor Cr to the voltage on the resonant capacitor Q4

Gradually become

The fourth step4 is the same as in the first embodiment, and will not be described again.

It should be noted that the frequency and the duty ratio of the sixth driving control signal are different from those of the fourth driving control signal in the first fourth stage step4, specifically, the frequency of the sixth driving control signal is greater than that of the fourth driving control signal, and the duty ratio of the sixth driving control signal is smaller than that of the fourth driving control signal.

In some possible embodiments, the four phases of the starting process of the power converter can be specifically realized as the following three modes:

And a drive control circuit, configured to generate a fifth drive control signal when the voltage regulator circuit regulates the voltage Vm of the second bridge arm from the voltage of the input power Vin to the first target voltage value, as shown in fig. 2f, in the fifth drive control signal, the drive control signals corresponding to the first switching tube Q1, the second switching tube Q2, the third switching tube Q3, and the fourth switching tube Q4 are all at a low level, and the fifth drive control signal may be used to turn off the first switching tube Q1, the second switching tube Q2, the third switching tube Q3, and the fourth switching tube Q4. Similarly, the fifth switch tube Q5, the sixth switch tube Q6, the seventh switch tube Q7 and the eighth switch tube Q8 in the secondary switch tube are all turned off.

When the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 are turned off, the output voltage Vo of the power converter drops at a certain rate under the traction of the load R, so that the voltage regulation circuit adjusts the voltage Vm of the second bridge arm to the first target voltage value as quickly as possible on the premise of meeting the current safety requirement of the voltage regulation circuit in order to avoid excessive drop. When the resonant capacitor Cr is small, the voltage adjustment can be completed without a large current, so that the step of controlling the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 to operate in the PWM state by using the PWM wave with a high frequency and a small duty ratio in the second and third stages step3 can be omitted, and the implementation is simpler.

It should be noted that the output end of the voltage regulating circuit may also be connected to the first bridge arm, at this time, the third switching tube Q3 is connected to the input power Vin of the power converter, and the first switching tube Q1 is connected to the output end of the voltage regulating circuit.

In the embodiment of the application, the power converter comprises a primary circuit, a secondary circuit, a resonant circuit and a driving control circuit, wherein the primary circuit comprises a primary switching tube, a voltage regulating circuit is additionally arranged in the primary circuit, the primary switching tube forms a first bridge arm and a second bridge arm, the secondary circuit comprises a secondary switching tube, the primary circuit is connected with the input end of the resonant circuit, and the secondary circuit is connected with the output end of the resonant circuit; the input end of the voltage regulating circuit is connected with an input power supply of the power converter, the output end of the voltage regulating circuit is connected with the second bridge arm, and the voltage regulating circuit is used for regulating the voltage of the second bridge arm in the starting process of the power converter; the driving control circuit is respectively connected with the primary side circuit and the secondary side circuit and used for generating driving control signals, and the driving control signals are used for controlling the conduction states of the primary side switching tube and the secondary side switching tube, so that the impact current in the starting process of the power converter can be effectively reduced, and the stability of the power converter during starting is improved.

Please refer to fig. 3, which is a flowchart illustrating a control method of a power converter according to an embodiment of the present disclosure. The control method of the power converter described in this embodiment is applied to a power converter, the power converter includes a primary circuit, a secondary circuit, a resonant circuit, and a drive control circuit, the primary circuit includes a primary switching tube and a voltage regulation circuit, the primary switching tube constitutes a first bridge arm and a second bridge arm, the secondary circuit includes a secondary switching tube, and the method includes:

101. and in the starting process of the power converter, controlling the voltage regulating circuit to regulate the output voltage so as to regulate the voltage of the second bridge arm.

In the specific implementation, in the starting process of the power converter, the voltage regulating circuit is controlled to regulate the output voltage, and the voltage of the second bridge arm is regulated to a first target voltage value, the voltage of the input power supply of the power converter, the first target voltage value and a second target voltage value in sequence.

102. And controlling a drive control circuit to generate drive control signals of the primary side circuit and the secondary side circuit according to the regulation of the voltage of the second bridge arm.

The primary side switch tube comprises a first switch tube, a second switch tube, a third switch tube and a fourth switch tube which are connected in a full-bridge mode, and the secondary side switch tube comprises a fifth switch tube, a sixth switch tube, a seventh switch tube and an eighth switch tube which are connected in the full-bridge mode.

In a specific implementation, when the voltage of the second bridge arm is adjusted to the first target voltage value, the driving control circuit may be controlled to generate a first driving control signal, the first driving control signal is used to control the first switching tube to be turned off, the second switching tube to be turned on, and the third switching tube and the fourth switching tube both work in a PWM state.

When the voltage of the second bridge arm is adjusted from the first target voltage value to the voltage of the input power supply, the drive control circuit can be controlled to generate a second drive control signal, and the second drive control signal is the same as the first drive control signal.

When the voltage of the second bridge arm is adjusted from the voltage of the input power supply to the first target voltage value, the driving control circuit can be controlled to generate a third driving control signal, the third driving control signal is used for controlling the first switching tube and the second switching tube to work in a PWM state, the third switching tube is turned on, and the fourth switching tube is turned off.

When the voltage of the second bridge arm is adjusted from the first target voltage value to the second target voltage value, the driving control circuit can be controlled to generate a fourth driving control signal, and the fourth driving control signal is used for controlling the first switching tube, the second switching tube, the third switching tube and the fourth switching tube to work in a PWM (pulse width modulation) state.

In some possible embodiments, the drive control circuit may be controlled to generate a fifth drive control signal when the voltage of the second bridge arm is adjusted from the voltage of the input power supply to the first target voltage value, where the fifth drive control signal is used to control the first switching tube, the second switching tube, the third switching tube and the fourth switching tube to be turned off, and the drive control circuit is controlled to generate a sixth drive control signal when the voltage of the second bridge arm is adjusted to the first target voltage value, where the sixth drive control signal is used to control the first switching tube, the second switching tube, the third switching tube and the fourth switching tube to operate in the PWM state.

The frequency and duty cycle of the sixth driving control signal are different from those of the fourth driving control signal, specifically, the frequency of the sixth driving control signal is greater than that of the fourth driving control signal, and the duty cycle of the sixth driving control signal is smaller than that of the fourth driving control signal.

In some possible embodiments, when the voltage of the second bridge arm is adjusted from the voltage of the input power source to the first target voltage value, only the drive control circuit may be controlled to generate the fifth drive control signal, where the fifth drive control signal is used to control the first switching tube, the second switching tube, the third switching tube and the fourth switching tube to be all turned off, and when the voltage of the second bridge arm is adjusted to the first target voltage value, the drive control circuit is not controlled to generate the sixth drive control signal, where the sixth drive control signal is used to control the first switching tube, the second switching tube, the third switching tube and the fourth switching tube to operate in the PWM state.

And the conduction state of the secondary side switching tube is correspondingly the same as the conduction state of the switching tube in the PWM working state in the primary side switching tube.

103. And controlling the conduction state of the primary side switching tube and the secondary side switching tube by using the driving control signal.

According to the embodiment of the application, the increased voltage regulating circuit is controlled to regulate the output voltage in the starting process of the power converter so as to regulate the voltage of the second bridge arm, and the driving control circuit is controlled to generate the driving control signals of the primary side circuit and the secondary side circuit according to the regulation of the voltage of the second bridge arm, so that the driving control signals are utilized to control the conduction state of the primary side switch tube and the secondary side switch tube, the impact current in the starting process of the power converter can be effectively reduced, and the stability of the power converter in the starting process is improved.

In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the application to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by wire (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wirelessly (e.g., infrared, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that incorporates one or more of the available media. The usable medium may be a magnetic medium (e.g., floppy Disk, hard Disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others.

In summary, the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.

Claims

1. A power converter, comprising: the primary circuit comprises a primary switch tube and a voltage regulating circuit, the primary switch tube forms a first bridge arm and a second bridge arm, and the secondary circuit comprises a secondary switch tube, wherein:

the primary side circuit is connected with the input end of the resonance circuit, and the secondary side circuit is connected with the output end of the resonance circuit;

the input end of the voltage regulating circuit is connected with an input power supply of the power converter, the output end of the voltage regulating circuit is connected with the second bridge arm, and the voltage regulating circuit is used for regulating the voltage of the second bridge arm in the starting process of the power converter;

the driving control circuit is respectively connected with the primary side circuit and the secondary side circuit and used for generating driving control signals of the primary side circuit and the secondary side circuit, and the driving control signals are used for controlling the conduction states of the primary side switch tube and the secondary side switch tube;

wherein,

the resonance circuit comprises a resonance capacitor and a transformer;

the midpoint of the first bridge arm in the primary side circuit is connected with the midpoint of the second bridge arm in the primary side circuit through a series circuit formed by the resonance capacitor and a primary coil of the transformer;

wherein,

the primary side switch tube comprises a first switch tube, a second switch tube, a third switch tube and a fourth switch tube which are connected in a full-bridge mode, the first switch tube and the second switch tube form the first bridge arm, and the third switch tube and the fourth switch tube form the second bridge arm;

the first switching tube is connected with the input power supply, the third switching tube is connected with the output end of the voltage regulating circuit, and the second switching tube and the fourth switching tube are connected with the grounding point of the power converter;

the secondary side switching tube comprises a fifth switching tube, a sixth switching tube, a seventh switching tube and an eighth switching tube which are connected in a full-bridge mode, the fifth switching tube and the sixth switching tube form a third bridge arm of the secondary side circuit, and the seventh switching tube and the eighth switching tube form a fourth bridge arm of the secondary side circuit;

2. The power converter of claim 1,

the voltage regulating circuit is specifically configured to regulate the voltage of the second bridge arm to a first target voltage value, the voltage of the input power supply, the first target voltage value, and a second target voltage value in sequence in a starting process of the power converter;

3. The power converter of claim 2,

the driving control circuit is specifically configured to generate a first driving control signal when the voltage regulating circuit regulates the voltage of the second bridge arm to the first target voltage value, where the first driving control signal is used to control the first switching tube to be turned off, the second switching tube is turned on, and the third switching tube and the fourth switching tube both work in a Pulse Width Modulation (PWM) state;

the driving control circuit is specifically configured to generate a second driving control signal when the voltage regulating circuit regulates the voltage of the second bridge arm to the voltage of the input power supply, where the second driving control signal is the same as the first driving control signal;

the driving control circuit is specifically configured to generate a third driving control signal when the voltage regulating circuit regulates the voltage of the second bridge arm to the first target voltage value again, where the third driving control signal is used to control the first switching tube and the second switching tube to work in a PWM state, the third switching tube is turned on, and the fourth switching tube is turned off;

4. The power converter of claim 2,

the driving control circuit is specifically configured to generate a first driving control signal when the voltage regulating circuit regulates the voltage of the second bridge arm to the first target voltage value, where the first driving control signal is used to control the first switching tube to be turned off, the second switching tube is turned on, and the third switching tube and the fourth switching tube both work in a PWM state;

the driving control circuit is specifically configured to generate a fifth driving control signal when the voltage regulating circuit regulates the voltage of the second bridge arm to the first target voltage value again, where the fifth driving control signal is used to control the first switching tube, the second switching tube, the third switching tube, and the fourth switching tube to be all turned off, and generate a sixth driving control signal when the voltage regulating circuit regulates the voltage of the second bridge arm to the first target voltage value, and the sixth driving control signal is used to control the first switching tube, the second switching tube, the third switching tube, and the fourth switching tube to all operate in a PWM state;

the driving control circuit is specifically configured to generate a fourth driving control signal when the voltage regulating circuit regulates the voltage of the second bridge arm to the second target voltage value, where the fourth driving control signal is used to control the first switching tube, the second switching tube, the third switching tube, and the fourth switching tube to all work in a PWM state;

5. The power converter of claim 2,

the driving control circuit is specifically configured to generate a fifth driving control signal when the voltage regulating circuit regulates the voltage of the second bridge arm to the first target voltage value again, where the fifth driving control signal is used to control the first switching tube, the second switching tube, the third switching tube, and the fourth switching tube to be turned off;

6. A power converter according to any one of claims 3 to 5,

7. The power converter of claim 1,

the primary side circuit further comprises a first filter capacitor and a second filter capacitor;

the first filter capacitor is positioned between the input power supply and the first bridge arm and is connected with the first bridge arm in parallel;

8. The power converter of claim 1,

the secondary side circuit further comprises a third filter capacitor;

9. The power converter according to any one of claims 1 to 5 or 7 to 8,

the voltage regulating circuit is a buck circuit or a buck boost circuit.

10. A control method of a power converter is characterized in that the power converter comprises a primary circuit, a secondary circuit, a resonant circuit and a driving control circuit, the primary circuit comprises a primary switch tube and a voltage regulating circuit, the primary switch tube forms a first bridge arm and a second bridge arm, the secondary circuit comprises a secondary switch tube, and the method comprises the following steps:

in the starting process of the power converter, controlling the voltage regulating circuit to regulate the output voltage so as to regulate the voltage of the second bridge arm;

controlling the driving control circuit to generate driving control signals of the primary side circuit and the secondary side circuit according to the regulation of the voltage of the second bridge arm;

controlling the conduction state of the primary side switch tube and the secondary side switch tube by using the driving control signal;

wherein, in the starting process of the power converter, the voltage regulating circuit is controlled to regulate the output voltage so as to regulate the voltage of the second bridge arm, and the method comprises the following steps:

in the starting process of the power converter, controlling the voltage regulating circuit to regulate output voltage, and regulating the voltage of the second bridge arm into a first target voltage value, the voltage of an input power supply, the first target voltage value and a second target voltage value in sequence;

the first target voltage value is smaller than or equal to a minimum value, and the second target voltage value is determined according to the target output voltage of the power converter;

the primary side switching tube comprises a first switching tube, a second switching tube, a third switching tube and a fourth switching tube which are connected in a full-bridge mode, the secondary side switching tube comprises a fifth switching tube, a sixth switching tube, a seventh switching tube and an eighth switching tube which are connected in the full-bridge mode, and the driving control circuit is controlled to generate driving control signals of the primary side circuit and the secondary side circuit according to the regulation of the voltage of the second bridge arm, and the driving control method comprises the following steps:

when the voltage of the second bridge arm is adjusted to the first target voltage value, the driving control circuit is controlled to generate a first driving control signal, the first driving control signal is used for controlling the first switching tube to be turned off, the second switching tube is turned on, and the third switching tube and the fourth switching tube both work in a PWM state;

when the voltage of the second bridge arm is adjusted to the voltage of the input power supply, controlling the drive control circuit to generate a second drive control signal, wherein the second drive control signal is the same as the first drive control signal;

when the voltage of the second bridge arm is adjusted to the first target voltage value again, the driving control circuit is controlled to generate a third driving control signal, the third driving control signal is used for controlling the first switching tube and the second switching tube to work in a PWM (pulse width modulation) state, the third switching tube is turned on, and the fourth switching tube is turned off;

11. The method of claim 10, wherein the primary side switching tube comprises a first switching tube, a second switching tube, a third switching tube and a fourth switching tube which are connected in a full-bridge manner, the secondary side switching tube comprises a fifth switching tube, a sixth switching tube, a seventh switching tube and an eighth switching tube which are connected in a full-bridge manner, and the driving control circuit is controlled to generate the driving control signals of the primary side circuit and the secondary side circuit according to the adjustment of the voltage of the second bridge arm, and the method comprises the following steps:

when the voltage of the second bridge arm is adjusted to the first target voltage value again, controlling the drive control circuit to generate a fifth drive control signal, wherein the fifth drive control signal is used for controlling the first switching tube, the second switching tube, the third switching tube and the fourth switching tube to be turned off, and when the voltage of the second bridge arm is adjusted to the first target voltage value, controlling the drive control circuit to generate a sixth drive control signal, and the sixth drive control signal is used for controlling the first switching tube, the second switching tube, the third switching tube and the fourth switching tube to work in a PWM state;

when the voltage of the second bridge arm is adjusted to the second target voltage value, controlling the drive control circuit to generate a fourth drive control signal, wherein the fourth drive control signal is used for controlling the first switching tube, the second switching tube, the third switching tube and the fourth switching tube to work in a PWM (pulse width modulation) state;

12. The method of claim 10, wherein the primary side switching tube comprises a first switching tube, a second switching tube, a third switching tube and a fourth switching tube which are connected in a full-bridge manner, the secondary side switching tube comprises a fifth switching tube, a sixth switching tube, a seventh switching tube and an eighth switching tube which are connected in a full-bridge manner, and the driving control circuit is controlled to generate the driving control signals of the primary side circuit and the secondary side circuit according to the adjustment of the voltage of the second bridge arm, and the method comprises the following steps:

when the voltage of the second bridge arm is adjusted to the first target voltage value again, the driving control circuit is controlled to generate a fifth driving control signal, and the fifth driving control signal is used for controlling the first switching tube, the second switching tube, the third switching tube and the fourth switching tube to be turned off;

13. The method according to any one of claims 10 to 12,