Delay synchronous rectification control method applied to soft start of bidirectional Buck/Boost converter
阅读说明：本技术 一种应用于双向Buck/Boost变换器软启动的延时同步整流控制方法 (Delay synchronous rectification control method applied to soft start of bidirectional Buck/Boost converter ) 是由 董梦雪 夏晨泰 陈姝慧 朱子锐 蓝建宇 董宝磊 谢伟 李阳 杨瑷玮 刘洋 于 2021-08-26 设计创作，主要内容包括：本发明涉及双向Buck/Boost变换器宽输入宽输出的技术领域,尤其涉及一种应用于双向Buck/Boost变换器软启动的延时同步整流控制方法,在开机时MOSFET主控管占空比从零并逐渐增大过程中,封锁MOSFET被控管驱动信号,利用MOSFET被控管的体二极管续流；待MOSFET主控管软启动结束,双向Buck/Boost变换器正常工作,再给MOSFET被控管施加与MOSFET主控管互补的驱动信号,实现同步整流。(The invention relates to the technical field of wide input and wide output of a bidirectional Buck/Boost converter, in particular to a delay synchronous rectification control method applied to soft start of the bidirectional Buck/Boost converter, wherein when the bidirectional Buck/Boost converter is started, the duty ratio of a MOSFET main control tube is gradually increased from zero, and in the process of gradually increasing, a drive signal of the MOSFET controlled tube is blocked, and the body diode of the MOSFET controlled tube is used for freewheeling; after the soft start of the MOSFET main control tube is finished, the bidirectional Buck/Boost converter works normally, and then a driving signal complementary with the MOSFET main control tube is applied to the MOSFET controlled tube to realize synchronous rectification.)
1. The utility model provides a be applied to time delay synchronous rectification control circuit of two-way Buck/Boost converter soft start which characterized in that: the bidirectional Buck/Boost converter comprises a bidirectional Buck/Boost converter, a sampling circuit, a control circuit and a drive circuit;
the bidirectional Buck/Boost converter comprises a power supply, a capacitor, an inductor, a first MOSFET and a second MOSFET; the first capacitor and the second capacitor are respectively connected in parallel at two ends of an input power supply and an output power supply, the anode of the input power supply is connected with the drain electrode of the first MOSFET, the source electrode of the first MOSFET is connected with the drain electrode of the second MOSFET and one end of the inductor, and the other end of the inductor is connected with the anode of the output power supply; the negative electrodes of the input power supply and the output power supply are both connected with the source electrode of the second MOSFET;
the sampling circuit is used for sampling the input voltage and the output voltage and sending the amplitude values of the input voltage and the output voltage and the rise time of the output voltage to the control circuit;
the control circuit is used for receiving input voltage and output voltage to determine whether the circuit works in a Buck mode or a Boost mode, generating a modulation signal after PI control and sending the modulation signal to the drive circuit;
the driving circuit is used for receiving the modulation signal, generating a driving signal after isolation and power amplification, and driving the MOSFET in the main circuit.
2. The method for controlling the delay synchronous rectification applied to the soft start of the bidirectional Buck/Boost converter, which is realized by the delay synchronous rectification control circuit applied to the soft start of the bidirectional Buck/Boost converter according to claim 1, is characterized by comprising the following steps of:
determining the working mode of the bidirectional Buck/Boost converter, and which of the first MOSFET and the second MOSFET is a MOSFET master control tube and which is a MOSFET controlled tube;
when the power is turned on, the duty ratio of the MOSFET main control tube is gradually increased from zero, the drive signal of the MOSFET controlled tube is blocked, and the body diode of the MOSFET controlled tube is used for follow current; after the soft start of the MOSFET main control tube is finished, the bidirectional Buck/Boost converter works normally, and then a driving signal complementary with the MOSFET main control tube is applied to the MOSFET controlled tube to realize synchronous rectification.
3. The method for controlling delay synchronous rectification applied to the soft start of the bidirectional Buck/Boost converter as claimed in claim 2, wherein the method for determining the operating mode of the bidirectional Buck/Boost converter and which of the first MOSFET and the second MOSFET is the MOSFET master control transistor and which is the MOSFET controlled transistor is as follows:
detecting input voltage V of input power supply and output power supply of bidirectional Buck/Boost converterinAnd an output voltage Vo(ii) a When the input voltage VinGreater than the output voltage VoWhen the bidirectional Buck/Boost converter works in a Buck mode, the first MOSFET is a MOSFET master control tube, and the second MOSFET is a MOSFET controlled tube; when the output voltage V isoGreater than the input voltage VinAnd meanwhile, the bidirectional Buck/Boost converter works in a Boost mode, the second MOSFET is a MOSFET main control tube, and the first MOSFET is a MOSFET controlled tube.
4. The delay synchronous rectification control method applied to the soft start of the bidirectional Buck/Boost converter according to claim 2, wherein when the bidirectional Buck/Boost converter works in a Buck mode, the second MOSFET is turned off, the expansion speed of the driving signal of the first MOSFET is adjusted, and the duty ratio is gradually increased from 0 to D1So that the output voltage is slowly increased from 0 to a given voltage, and soft start is realized.
5. The delay synchronous rectification control method applied to the soft start of the bidirectional Buck/Boost converter according to claim 2, wherein when the bidirectional Buck/Boost converter works in a Boost mode, the first MOSFET is turned off, the expansion speed of the driving signal of the second MOSFET is adjusted, and the duty ratio is gradually increased from 0 to d2So that the output voltage is slowly increased from 0 to a given voltage, and soft start is realized.
6. The delay synchronous rectification control method applied to the soft start of the bidirectional Buck/Boost converter according to claim 2, wherein the expansion speed of the driving signal of the main control tube is adjusted according to the time tr when the output voltage rises to a given value.
7. The delay synchronous rectification control method applied to the soft start of the bidirectional Buck/Boost converter as recited in claim 6, wherein when K is less than or equal to N, and at (K-1) T-KT, the duty ratio of the driving signal of the main control tube of the bidirectional Buck/Boost converter is set to KU, the driving of the controlled tube is 0, and the converter normally works. Wherein, T is the time period of the drive signal of the main control tube of the bidirectional Buck/Boost converter, N is tr/T, K is a positive integer, and 1, 2, 3, …, N-1 and N are taken in sequence. When K is equal to N, the output voltage rises to a given voltage, and the soft start process is finished.
8. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 2 to 7.
9. A time-delay synchronous rectification control device applied to soft start of a bidirectional Buck/Boost converter, comprising a memory, a processor and a computer program stored in the memory and operable on the processor, wherein: the processor, when executing the computer program, performs the steps of the method according to any one of claims 2 to 7.
Technical Field
The invention relates to the technical field of wide input and wide output of a bidirectional Buck/Boost converter, in particular to a delay synchronous rectification control method applied to soft start of the bidirectional Buck/Boost converter.
Background
With the increasing concern about energy, environmental protection and other problems, electric vehicles are rapidly developed, however, under the existing technical conditions, the performance of the power battery becomes a major bottleneck restricting the development of the electric vehicles. The bidirectional DC/DC conversion technology can optimize the control of the motor and improve the overall efficiency performance of the electric automobile. The power supply of the electric vehicle needs to realize bidirectional flow of input current and output current, and can realize bidirectional energy transmission through a bidirectional DC/DC converter, wherein the bidirectional Buck/Boost converter is one of topologies of the bidirectional DC/DC converter.
The bidirectional Buck/Boost converter has the advantages of being simple to control, reliable in topology, capable of achieving a high power level and the like, and is suitable for being applied to a vehicle-mounted energy management system. The two ends of the converter are respectively connected with the direct current bus and the storage battery to take the role of bidirectional energy conversion of the system, so that the bidirectional converter plays a very important role in energy management of the system. It is different from the application of traditional single-end source single-end load, but works in the situation that both ends are voltage sources.
For a Buck/Boost bidirectional synchronous rectification converter, a soft start method is generally required to reduce surge current when the converter is started. The traditional soft start is to gradually increase the duty ratio of the converter main control tube from zero to a stable value, which is feasible for the application occasions of single-ended source and single-ended dissipative load. For a bidirectional converter, a conventional soft start can be used if it is considered as a unidirectional DC/DC converter for two directions at different times, respectively. However, in the system, the bidirectional DC/DC converter is equivalent to connecting the power supply to both ends. If the system is in the startup soft start process, the controlled tube and the main control tube work complementarily, the duty ratio of the controlled tube is gradually reduced from the full duty ratio, and the circuit has problems.
If the traditional soft start method is adopted, the bidirectional converter of the two-end source type has large reverse current because the controlled tube and the main control tube are conducted in a complementary mode. In order to prevent the occurrence of reverse current, when the system is started up in a soft mode, the controlled tube cannot work in a synchronous rectification state, namely the controlled tube is not opened to prevent a path for providing reverse current for an output end source, and in the process, the current continues for the inductive current only through a body diode of the controlled tube; after the main control tube finishes soft start, the bidirectional converter works normally, and then a driving signal is applied to the controlled tube to realize synchronous rectification.
Disclosure of Invention
The technical problem solved by the invention is as follows: the control method is reliable, simple in circuit and easy to implement, and has the advantages that the current stress is small, the circuit is more stable and reliable in starting, and the control method has higher engineering use value.
The technical solution of the invention is as follows: a delay synchronous rectification control circuit applied to soft start of a bidirectional Buck/Boost converter comprises the bidirectional Buck/Boost converter, a sampling circuit, a control circuit and a drive circuit;
the bidirectional Buck/Boost converter comprises a power supply, a capacitor, an inductor, a first MOSFET and a second MOSFET; the first capacitor and the second capacitor are respectively connected in parallel at two ends of an input power supply and an output power supply, the anode of the input power supply is connected with the drain electrode of the first MOSFET, the source electrode of the first MOSFET is connected with the drain electrode of the second MOSFET and one end of the inductor, and the other end of the inductor is connected with the anode of the output power supply; the negative electrodes of the input power supply and the output power supply are both connected with the source electrode of the second MOSFET;
the sampling circuit is used for sampling the input voltage and the output voltage and sending the amplitude values of the input voltage and the output voltage and the rise time of the output voltage to the control circuit;
the control circuit is used for receiving input voltage and output voltage to determine whether the circuit works in a Buck mode or a Boost mode, generating a modulation signal after PI control and sending the modulation signal to the drive circuit;
the driving circuit is used for receiving the modulation signal, generating a driving signal after isolation and power amplification, and driving the MOSFET in the main circuit.
The delay synchronous rectification control method applied to the soft start of the bidirectional Buck/Boost converter, which is realized by the delay synchronous rectification control circuit applied to the soft start of the bidirectional Buck/Boost converter, comprises the following steps:
determining the working mode of the bidirectional Buck/Boost converter, and which of the first MOSFET and the second MOSFET is a MOSFET master control tube and which is a MOSFET controlled tube;
when the power is turned on, the duty ratio of the MOSFET main control tube is gradually increased from zero, the drive signal of the MOSFET controlled tube is blocked, and the body diode of the MOSFET controlled tube is used for follow current; after the soft start of the MOSFET main control tube is finished, the bidirectional Buck/Boost converter works normally, and then a driving signal complementary with the MOSFET main control tube is applied to the MOSFET controlled tube to realize synchronous rectification.
Further, the method for determining the operating mode of the bidirectional Buck/Boost converter and which of the first MOSFET and the second MOSFET is the MOSFET master control transistor and which is the MOSFET controlled transistor comprises the following steps:
detecting input voltage V of input power supply and output power supply of bidirectional Buck/Boost converterinAnd an output voltage Vo(ii) a When the input voltage VinGreater than the output voltage VoWhen the bidirectional Buck/Boost converter works in a Buck mode, the first MOSFET is a MOSFET master control tube, and the second MOSFET is a MOSFET controlled tube; when the output voltage V isoGreater than the input voltage VinAnd meanwhile, the bidirectional Buck/Boost converter works in a Boost mode, the second MOSFET is a MOSFET main control tube, and the first MOSFET is a MOSFET controlled tube.
Further, when bidirectionalWhen the Buck/Boost converter works in the Buck mode, the second MOSFET is turned off, the expansion speed of the driving signal of the first MOSFET is adjusted, and the duty ratio is gradually increased from 0 to D1So that the output voltage is slowly increased from 0 to a given voltage, and soft start is realized.
Further, when the bidirectional Buck/Boost converter works in a Boost mode, the first MOSFET is turned off, the expansion speed of a driving signal of the second MOSFET is adjusted, and the duty ratio is gradually increased from 0 to d2So that the output voltage is slowly increased from 0 to a given voltage, and soft start is realized.
Further, the unfolding speed of the driving signal of the main control tube is adjusted according to the time tr when the output voltage rises to the given value.
Further, when K is less than or equal to N, and at (K-1) T-KT, the duty ratio of a driving signal of a main control tube of the bidirectional Buck/Boost converter is set to KU, a controlled tube is driven to 0, and the converter normally works. Wherein, T is the time period of the drive signal of the main control tube of the bidirectional Buck/Boost converter, N is tr/T, K is a positive integer, and 1, 2, 3, …, N-1 and N are taken in sequence. When K is equal to N, the output voltage rises to a given voltage, and the soft start process is finished.
A computer-readable storage medium storing a computer program which, when executed by a processor, implements the steps of the method for controlling delay-locked synchronous rectification applied to soft start of a bidirectional Buck/Boost converter.
The delay synchronous rectification control device applied to the soft start of the bidirectional Buck/Boost converter comprises a memory, a processor and a computer program which is stored in the memory and can run on the processor, wherein the processor realizes the steps of the delay synchronous rectification control method applied to the soft start of the bidirectional Buck/Boost converter when executing the computer program.
Compared with the prior art, the invention has the advantages that:
the invention solves the problem of reverse increase of the inductive current of the converter when the traditional soft start method is started by adopting a time delay synchronous rectification control strategy. Under the condition that two ends of the bidirectional Buck/Boost converter are both provided with sources, the bidirectional Buck/Boost converter can be started normally, and safe and reliable operation of the system is realized.
Drawings
FIG. 1 is a circuit diagram of a bidirectional Buck/Boost converter
FIG. 2 shows a soft start process Q in Buck mode1And Q2Schematic diagram of driving signals
FIG. 3 shows a soft start process Q in Boost mode1And Q2Schematic diagram of driving signals
FIG. 4 is a control flow chart of the delay synchronous rectification control method
FIGS. 5 and 6 are graphs comparing waveforms of inductive current using conventional soft start method and delayed synchronous rectification control method of the present invention
Detailed Description
In order to better understand the technical solutions, the technical solutions of the present application are described in detail below with reference to the drawings and specific embodiments, and it should be understood that the specific features in the embodiments and examples of the present application are detailed descriptions of the technical solutions of the present application, and are not limitations of the technical solutions of the present application, and the technical features in the embodiments and examples of the present application may be combined with each other without conflict.
The delay synchronous rectification control method applied to the soft start of the bidirectional Buck/Boost converter provided by the embodiment of the present application is further described in detail with reference to the drawings in the specification, and specific implementation manners may include (as shown in fig. 1 to 6): the bidirectional Buck/Boost converter is a main power circuit and is matched with a sampling circuit, a control circuit, a driving circuit and the like. The method comprises the steps of controlling 2 MOSFETs of a bidirectional Buck/Boost converter, adopting a time-delay synchronous rectification control strategy, blocking a driving signal of a controlled tube in the process that the duty ratio of a main control tube is gradually increased from zero when the bidirectional Buck/Boost converter is started, and utilizing a body diode of the controlled tube to carry out follow current, so that inductive current cannot reversely flow. After the soft start of the main control tube is finished, the bidirectional converter works normally, and then a driving signal complementary to the main control tube is applied to the controlled tube to realize synchronous rectification.
The bidirectional Buck/Boost converter isA main power circuit including 2 switching tubes Q1And Q2And 2 anti-parallel diodes D of switch tubes1And D2Filter inductance L1Filter capacitor CHAnd CL。
The delay synchronous rectification control circuit applied to the soft start of the bidirectional Buck/Boost converter comprises the bidirectional Buck/Boost converter, a sampling circuit, a control circuit and a drive circuit;
the bidirectional Buck/Boost converter comprises a power supply, a capacitor, an inductor, a first MOSFET and a second MOSFET; the first capacitor and the second capacitor are respectively connected in parallel at two ends of an input power supply and an output power supply, the anode of the input power supply is connected with the drain electrode of the first MOSFET, the source electrode of the first MOSFET is connected with the drain electrode of the second MOSFET and one end of the inductor, and the other end of the inductor is connected with the anode of the output power supply; the negative electrodes of the input power supply and the output power supply are both connected with the source electrode of the second MOSFET;
the sampling circuit is used for sampling the input voltage and the output voltage and sending the amplitude values of the input voltage and the output voltage and the rise time of the output voltage to the control circuit;
the control circuit is used for receiving input voltage and output voltage to determine whether the circuit works in a Buck mode or a Boost mode, generating a modulation signal after PI control and sending the modulation signal to the drive circuit;
the driving circuit is used for receiving the modulation signal, generating a driving signal after isolation and power amplification, and driving the MOSFET in the main circuit.
The invention provides a delay synchronous rectification control method for soft start of a bidirectional Buck/Boost converter, which is used for detecting the input voltage V of the converterinAnd an output voltage VoWhen the input voltage V isinGreater than the output voltage VoWhile the converter is operating in Buck mode, with Q1Is a master control tube, Q2Duty ratio d for controlled control1＝Vo/Vin. When the output voltage V isoGreater than the input voltage VinWhen the converter is operating in Boost mode, Q2Is a master control tube, Q1Duty ratio d for controlled control21-Vin/Vo。
The invention provides a delay synchronous rectification control method for soft start of a bidirectional Buck/Boost converter1The developing speed of the driving signal is increased gradually from 0 to D1Period controlled Q2And turning off the circuit, so that the output voltage slowly rises from 0 to a given voltage, and soft start is realized. After the soft start is finished, the main control tube Q1Duty ratio of drive signal d1Controlled tube Q2The duty ratio of the driving signal is 1-d1。
The invention provides a delay synchronous rectification control method for soft start of a bidirectional Buck/Boost converter2The developing speed of the driving signal is increased gradually from 0 to d2Period controlled Q1And turning off the circuit, so that the output voltage slowly rises from 0 to a given voltage, and soft start is realized. After the soft start is finished, the main control tube Q2Duty ratio of drive signal d2Controlled tube Q1The duty ratio of the driving signal is 1-d2。
The unfolding speed of the driving signal of the main control tube is adjusted according to the time tr when the output voltage rises to a given value, and the specific process is as follows: when K is less than or equal to N (N is tr/T), and when (K-1) T-KT, the duty ratio of the driving signal of the main control tube of the bidirectional Buck/Boost converter is set to KU, the driving of the controlled tube is 0, and the converter normally works. Wherein T is the time period of a driving signal of a main control tube of the bidirectional Buck/Boost converter, K is a positive integer, and 1, 2, 3, …, N-1 and N are sequentially selected. When K is equal to N, the output voltage rises to a given voltage, and the soft start process is finished.
After the soft start is finished, under Buck mode, the main control tube Q1Duty ratio of drive signal d1Controlled tube Q2The duty ratio of the driving signal is complementary with that of the main control tube and is 1 to d1. Under Boost mode, the main control tube Q2Duty ratio of drive signal d2Controlled tube Q1The duty ratio of the driving signal is 1-d2。
In the scheme provided by the embodiment of the application, as shown in fig. 1, the bidirectional Buck/Boost converter circuit diagram is provided. The bidirectional Buck/Boost converter is a main power circuit and is matched with a sampling circuit, a control circuit, a driving circuit and the like. The sampling circuit samples the time tr when the output voltage rises to a given value, and the unfolding speed of the driving signal of the main control tube is adjusted according to the time tr when the output voltage rises to the given value. When the machine is started, the duty ratio of the main control tube is gradually increased from zero, the driving signal of the controlled tube is blocked, and the body diode of the controlled tube is used for continuous flow, so that the inductive current cannot reversely flow. After the soft start of the main control tube is finished, the bidirectional converter works normally, and then a driving signal complementary to the main control tube is applied to the controlled tube to realize synchronous rectification.
When the converter works in Buck mode, the main control tube Q is adjusted1The developing speed of the driving signal is increased gradually from 0 to D1Period controlled Q2And turning off the circuit, so that the output voltage slowly rises from 0 to a given voltage, and soft start is realized. After the soft start is finished, the main control tube Q1Duty ratio of drive signal d1Controlled tube Q2The duty ratio of the driving signal is 1-d1. FIG. 2 shows a soft start process Q in Buck mode1And Q2Schematic diagram of the driving signal of (1).
When the converter works in Boost mode, the main control tube Q is adjusted2The developing speed of the driving signal is increased gradually from 0 to d2Period controlled Q1And turning off the circuit, so that the output voltage slowly rises from 0 to a given voltage, and soft start is realized. After the soft start is finished, the main control tube Q2Duty ratio of drive signal d2Controlled tube Q1The duty ratio of the driving signal is 1-d2. FIG. 3 shows a soft start process Q in Boost mode1And Q2Schematic diagram of the driving signal of (1).
The invention provides a soft start delay synchronous rectification control method of a bidirectional Buck/Boost converter, and a control flow chart is shown in FIG. 4, and the method specifically works as follows:
when the voltage is between 0 and T, the duty ratio of a driving signal of a main control tube of the bidirectional Buck/Boost converter is set to be U, a controlled tube drives to be U, and the converter normally works;
in T-2T, the duty ratio of a driving signal of a main control tube of the bidirectional Buck/Boost converter is set to be 2U, a controlled tube is driven to be 0, and the converter normally works;
when the voltage is between 2T and 3T, the duty ratio of a driving signal of a main control tube of the bidirectional Buck/Boost converter is set to be 3U, a controlled tube is driven to be 0, and the converter normally works;
by analogy, when K is less than N (N is tr/T), and when (K-1) T-KT, the duty ratio of the driving signal of the main control tube of the bidirectional Buck/Boost converter is set to KU, the driving of the controlled tube is 0, and the converter normally works. And T is the time period of the driving signal of the main control tube of the bidirectional Buck/Boost converter.
Fig. 5 and 6 are graphs comparing waveforms of the inductor current using the conventional soft start method with the delayed synchronous rectification control method of the present invention, and it can be seen from the graphs that since both ends of the circuit can be regarded as voltage sources, if the conventional soft start technique is used, the inductor current is rapidly and reversely increased and the inductor is saturated in the process that the synchronous tube is gradually decreased from the full duty ratio, and finally the switch tube is damaged by overcurrent. If a time-delay synchronous rectification control strategy is adopted, the drive signal of the controlled tube is blocked in the process that the duty ratio of the main control tube is gradually increased from zero when the machine is started, and the body diode of the controlled tube is used for follow current, so that the inductive current cannot reversely flow. After the soft start of the main control tube is finished, the bidirectional converter works normally, and then a driving signal complementary to the main control tube is applied to the controlled tube to realize synchronous rectification. Compared with the traditional soft start method, the delay synchronous rectification control strategy solves the problem that the inductor current of the converter is reversely increased when the traditional soft start method is started. Under the condition that two ends of the bidirectional Buck/Boost converter are both provided with sources, the bidirectional Buck/Boost converter can be started normally, and safe and reliable operation of the system is realized.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.
Those skilled in the art will appreciate that those matters not described in detail in the present specification are well known in the art.
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