WO2020024200A1

WO2020024200A1 - Direct current buck-boost circuit

Info

Publication number: WO2020024200A1
Application number: PCT/CN2018/098236
Authority: WO
Inventors: 刘鹏飞; 赵德琦; 吴壬华; 邓向钖; 唐疑军; 刘晓红
Original assignee: 深圳欣锐科技股份有限公司
Priority date: 2018-08-02
Filing date: 2018-08-02
Publication date: 2020-02-06
Also published as: CN110168892A

Abstract

Disclosed in the embodiments of the present application is a direct current buck-boost circuit, comprising: a control feedback module, a first drive module, a second drive module, a voltage sampling module and a buck-boost circuit module. An input end of the control feedback module is electrically connected to an output end of the voltage sampling module, a first output end of the control feedback module is connected to an input end of the first drive module, and a second output end of the control feedback module is connected to an input end of the second drive module. The boost-buck circuit module comprises a first switch and a second switch, an output end of the first drive module is connected to one end of the first switch, and an output end of the second drive module is connected to one end of the second switch. An input end of the voltage sampling module is connected to an output end of the buck-boost circuit module. The embodiments of the present application can improve the conversion speed between boost and buck, realizing seamless transition from buck to boost and boost to buck, and improving the circuit response efficiency.

Description

DC buck-boost circuit

Technical field

The present application relates to the field of electronic power technology, and in particular, to a DC buck-boost circuit.

Background technique

The basic buck-boost DC conversion circuit can achieve buck-boost, but its output voltage has the opposite polarity to the input voltage, so it is rarely used in actual projects. Modern engineers have done a lot of research on buck-boost DC converters and designed a variety of DC converter topologies, but these topologies are often applied to power factor correction, etc. At the same time, their algorithms are quite complex and the circuit response efficiency Low, not convenient for practical operation.

Summary of the invention

The embodiments of the present application provide a DC step-up and step-down circuit, which can improve the conversion speed between step-up and step-down, realize a seamless transition from step-up to step-up and step-up to step-down, and improve circuit response efficiency.

An embodiment of the present application provides a DC buck-boost circuit, including:

A control feedback module, a first driving module, a second driving module, a voltage sampling module, and a step-up and step-down circuit module;

An input terminal of the control feedback module is electrically connected to an output terminal of the voltage sampling module, a first output terminal of the control feedback module is connected to an input terminal of the first drive module, and a second terminal of the control feedback module The output end is connected to the input end of the second driving module; the step-up and step-down circuit module includes a first switch and a second switch, and the output end of the first driving module is connected to one end of the first switch, and The output terminal of the second driving module is connected to one end of the second switch; the input terminal of the voltage sampling module is connected to the output terminal of the buck-boost circuit module;

The voltage sampling module samples the output voltage of the buck-boost circuit module to obtain a sample value of the output voltage, and sends the sampled value of the output voltage to the control feedback module; the control feedback module uses the A feedback value is calculated from a sampled value of the output voltage and a reference value of the output voltage, and a first duty ratio and a second duty ratio are determined according to a value interval in which the feedback value is located. The value corresponding to the range of the feedback value The interval includes two or more intervals, the first duty cycle is the duty cycle of the first switch, and the second duty cycle is the duty cycle of the second switch; the control feedback The module controls the first driving module to send a first pulse signal to the first switch and the second driving module to send a second pulse signal to the second switch. The first pulse signal is to make the first The duty ratio of a switch is a pulse signal of the first duty ratio, and the second pulse signal is a pulse signal of a duty ratio of the second switch to the second duty ratio.

As an optional implementation manner, the value interval corresponding to the value range of the feedback value includes a first interval and a second interval, and the control feedback module includes an occupation of the first interval and the first switch. A corresponding relationship between the duty ratio and the duty ratio of the second switch, and a corresponding relationship between the second interval and the duty ratio of the first switch and the duty ratio of the second switch.

As an optional implementation manner, the duty ratio of the first switch corresponding to the first interval ranges from M% to N%, and the duty ratio of the corresponding second switch is 0%; The M is greater than or equal to 0, and the N is less than or equal to 100.

As an optional implementation manner, when the feedback value is in the first interval, the feedback value is positively related to the duty cycle of the first switch.

As an optional implementation manner, the duty ratio of the second switch corresponding to the second interval ranges from P% to Q%, and the duty ratio of the corresponding first switch is 100%; The P is greater than or equal to 0, and the Q is less than or equal to 100.

As an optional implementation manner, when the feedback value is in the second interval, the feedback value is positively related to the duty cycle of the second switch.

As an optional implementation manner, the step-up and step-down circuit module includes a DC step-down module and a DC step-up module, and the DC step-down module and the DC step-up module are connected in cascade; the step-up and step-down circuit The module performs a voltage reduction function through the DC step-down module when the second switch is turned off and the first switch is operating. The step-up and step-down circuit module is turned on when the first switch is turned on and the second switch is turned on. A boost function is performed by the DC boost module during operation.

As an optional implementation manner, the control feedback module is a digital signal processor.

As an optional implementation manner, the first pulse signal and the second pulse signal are both pulse width modulation signals; and when the feedback value is within the first interval, the step-up and step-down voltages The circuit operates in a step-down mode that performs the step-down function; and when the feedback value is within the second interval, the step-up and step-down circuit operates in a step-up mode that performs the step-up function.

As an optional implementation manner, the first switch and the second switch are both an insulated gate bipolar transistor or a power field effect transistor; a value interval corresponding to the value range of the feedback value includes a third interval, A transition interval and a fourth interval, the control feedback module includes a correspondence between the transition interval and the duty cycle of the first switch and the duty cycle of the second switch, and the feedback value is in the In the case of a transition interval, the step-up and step-down circuit module is in a transition circuit stage of transitioning from the boost mode to the buck mode or from the buck mode to the boost mode.

In the embodiment of the present application, the voltage sampling module samples the output voltage of the buck-boost circuit module to obtain a sample value of the output voltage, and sends the sample value to the control feedback module; the control feedback module uses the sample value and the output voltage The reference value is used to calculate the feedback value. The value range corresponding to the value range of the feedback value includes two or more intervals. The control feedback module determines the first switch and the first switch according to the value interval in which the calculated feedback value is located. Duty ratio of two switches, the control feedback module controls the first drive module to send a first pulse signal to the first switch, and controls the second drive module to send a second pulse signal to the second switch, The first pulse signal is a pulse such that the duty ratio of the first switch is the first duty ratio, and the second pulse signal is a pulse such that the duty ratio of the second switch is the second Duty-cycle pulse; it can increase the conversion speed between boost and buck, high conversion efficiency, fast response speed, and seamless transition from buck to boost and boost to buck

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly explain the technical solutions in the embodiments of the present application, the drawings that need to be used in the embodiments of the present application will be described below.

FIG. 1 is a schematic structural diagram of a DC buck-boost circuit provided by an embodiment of the present application;

FIG. 2 is a schematic structural diagram of a DC buck-boost circuit provided by another embodiment of the present application; FIG.

FIG. 3 is a schematic diagram of a pulse signal according to an embodiment of the present application.

detailed description

The following describes the embodiments of the present application with reference to the drawings in the embodiments of the present application. The terms "first", "second", and the like in the description and claims of the present application and the above-mentioned drawings are used to distinguish different objects, and are not used to describe a specific order. Furthermore, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device containing a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes Other steps or units inherent to these processes, methods or equipment.

Please refer to FIG. 1, which is a schematic structural diagram of a DC buck-boost circuit disclosed in an embodiment of the present application. As shown in FIG. 1, the DC buck-boost circuit described in this embodiment includes a control feedback module 10, a first drive module 20, a second drive module 30, a voltage sampling module 40, and a buck-boost circuit module 50; :

The input terminal 11 of the control feedback module 10 is electrically connected to the output terminal 41 of the voltage sampling module 40, the first output terminal 12 of the control feedback module 10 is connected to the input terminal 21 of the first drive module 20, and the control feedback module The second output terminal 13 of 10 is connected to the input terminal 31 of the second driving module 30; the buck-boost circuit module 50 includes a first switch 51 and a second switch 52, and an output terminal 22 of the first driving module 20 is connected to the above. An end of the first switch 51, an output terminal 32 of the second driving module 30 is connected to one end of the second switch 52, and an input terminal 42 of the voltage sampling module 40 is connected to an output terminal 53 of the buck-boost circuit module 50.

In the embodiment of the present application, the voltage sampling module 40 samples the output voltage of the buck-boost circuit module 50 to obtain a sample value of the output voltage, and sends the sample value of the output voltage to the control feedback module 10; the control feedback module 10 Use the sampled value of the output voltage and the reference value of the output voltage to calculate the feedback value, and determine the first duty cycle and the second duty cycle according to the value interval in which the feedback value is located. The range of the value of the feedback value corresponds to The value interval includes two or more intervals, the first duty ratio is the duty ratio of the first switch 51, and the second duty ratio is the duty ratio of the second switch 52; the control feedback module 10 Controlling the first driving module 20 to send a first pulse signal to the first switch 51 and controlling the second driving module 30 to send a second pulse signal to the second switch 52, the first pulse signal is to make the first switch 51 The duty ratio of is the pulse of the first duty ratio, and the second pulse signal is a pulse of which the duty ratio of the second switch 52 is the second duty ratio. .

The duty ratio in the embodiments of the present application refers to the ratio of the power-on time to the total time in a pulse cycle. It can also be understood as the ratio of the switch-on time to the duty cycle, for example: A pulse sequence with a pulse width of 1 μs and a signal period of 4 μs has a duty cycle of 0.25.

There are currently many ways to determine the feedback value corresponding to the DC buck-boost circuit according to the sampled value of the output voltage. The embodiments of this application do not limit the way to determine the feedback value, and any of the current ways can be adopted. In the embodiment of the present application, the value interval corresponding to the range of the feedback value includes two or more intervals, that is, the occupation of the first switch 51 and the second switch 52 corresponding to the case where the feedback value is in different intervals. The air ratio is different. The control feedback module 10 may store a reference value of the output voltage in advance, and the control feedback module 10 may compare the sampled value with the reference value of the output voltage, and determine the feedback value according to the comparison result. The value interval corresponding to the value range of the above feedback value may be two consecutive value intervals. For example, the value range of the feedback value is 0-32767, and the value range corresponding to the value range includes the first interval of 0-10000. And the second interval 10001-32767; the first interval 0-10000 corresponds to the duty cycle of the first switch 51 is 0% -100%, the second switch 52 has a duty cycle of 0%; the second interval 10001-32767 corresponds The duty cycle of the second switch 52 is 0% -80%, and the duty ratio of the first switch 51 is 100%; if the feedback value is 10000, the duty ratio of the first switch 51 is 100%, and the second switch The duty ratio of 52 is 0%; if the feedback value is 32767, the duty ratio of the second switch 52 is 80%, and the duty ratio of the first switch 51 is 100%. The value range corresponding to the above range of feedback values can be divided according to the comparison between the step-down amplitude and the step-up amplitude. For example, when the voltage is 300V, a voltage change of 290-800V needs to be achieved through a step-up and step-down circuit. The value interval corresponding to the value range of the feedback value can be divided into a first interval of 0-3000 and a second interval of 3001-32767, that is, the step-down amplitude is relatively small compared to the step-up amplitude. The range is smaller than the range of the second interval corresponding to the feedback value during the boost.

Optionally, the value interval corresponding to the range of the feedback value may also be two discrete value intervals. For example, the value range of the feedback value is 0-32767, and the value range corresponds to the first interval 0. -19000 and the second interval 20000-32767; the first interval 0-19000 corresponds to the duty cycle of the first switch 51 is 0% -100%, the second switch 52 has a duty cycle of 0%; the second interval 20000- The duty ratio of 32767 corresponding to the second switch 52 is 0% -80%, and the duty ratio of the first switch 51 is 100%. The control feedback module 10 may judge the obtained feedback value. If the two discontinuous numerical intervals do not include the feedback value obtained by the control feedback module 10, the control feedback module 10 may re-acquire the sampling value and calculate the feedback value until it is obtained. The feedback value of is located between these two discrete numerical intervals.

Optionally, the numerical interval corresponding to the value range of the feedback value may also be two numerical intervals where there is an overlapping interval. If the feedback value obtained by controlling the feedback module 10 is in an overlapping interval between the first interval and the second interval, at this time, the step-up circuit and the step-down circuit work simultaneously. For example, the value range of the feedback value is 0-32767, and the value range corresponds to the first interval 0-21000 and the second interval 20000-32767. If the feedback value obtained by controlling the feedback module 10 is in the overlapping range of 20000-21000, the boost circuit and the buck circuit can work at the same time, and the duty ratios of the first switch 51 and the second switch 52 can still be based on the preset feedback during operation. The corresponding relationship between the value and the duty ratio (the first duty ratio and the second duty ratio) is determined. In general, the value range corresponding to the value range of the feedback value can be divided according to the actual situation, to achieve a smooth change of step-up and step-down, and fast response efficiency.

In the embodiment of the present application, the duty ratio of the switch refers to the ratio of the on-time of the switch to the total time, and the total time is the sum of the on-time and the off-time of the switch. For example, a certain switch has a duty cycle of 40%. It can be understood that the switch is on 40% of the time and the switch is off 60% of the time. In the embodiment of the present application, the DC step-up and step-down circuit can quickly realize the conversion between step-down and step-up. For example, the current DC buck-boost circuit works in the buck mode. If the DC buck-boost circuit needs to be switched to the boost mode, the control feedback module determines the duty cycle of each switch according to the calculated feedback value and generates The corresponding control signal enables the DC buck-boost circuit to switch from the buck mode to the boost mode by controlling the turning off of each switch, and the output voltage meets the demand by controlling the duty cycle of each switch in the boost mode.

The range of the feedback value in different circuits may be different, and the value range corresponding to the range of the feedback value may also be different. For example, the first value range of the feedback value in the first DC buck-boost circuit is 0-32767, and the second value range of the feedback value in the second DC buck-boost circuit is 0-12767. The two value ranges corresponding to the first value range 0-32767 can be 0-10000 and 10001-32767; they can also be 0-15000 and 15001-32767. That is, the value range of the feedback value can be divided according to the specific circuit, and the value range corresponding to the value range of the feedback value in different DC buck-boost circuits can be different. Since the transfer functions of the buck circuit (buck circuit) and the boost circuit (boost circuit) are different, different algorithms can be added to the feedback values corresponding to the duty cycles of the switches. For example, assuming that the transfer function of the step-down circuit in the third DC step-up and step-down circuit is the first transfer function, the range of the duty cycle of the first switch in the step-down mode is 0% -60%, and the range of the corresponding feedback value is 0-10000, the duty ratio of the second switch is 0%; assuming that the transfer function of the buck circuit in the fourth DC buck-boost circuit is the second transfer function, the duty ratio of the first switch in the buck mode is The range is 10% -80%, the corresponding feedback value ranges from 0-20000, and the duty cycle of the second switch is 0%.

The first switch 51 and the second switch 52 may be a power field effect transistor, a power transistor, an insulated gate bipolar transistor, and the like. The first switch 51 and the second switch 52 can be turned on and off under the control of a pulse signal. The first driving module 20 and the second driving module 30 may be the same driving circuit, and both may convert the control signal from the control feedback module into a pulse signal that can turn on or off the switch.

In the embodiment of the present application, the value range of the feedback value may correspond to two or more numerical intervals, and the control feedback module determines the duty cycle of the first switch and the second switch according to the numerical interval in which the calculated feedback value is located. , Can increase the conversion speed between step-up and step-down, to achieve a seamless transition from step-up to step-up and step-up to step-down.

Please refer to FIG. 2, which is a schematic structural diagram of a DC buck-boost circuit disclosed in an embodiment of the present application. As shown in FIG. 2, the DC buck-boost circuit described in this embodiment includes: a control feedback module 10, a first drive module 20, a second drive module 30, a voltage sampling module 40, and a buck-boost circuit module 50;

The input terminal 11 of the control feedback module 10 is electrically connected to the output terminal 41 of the voltage sampling module 40, the first output terminal 12 of the control feedback module 10 is connected to the input terminal 21 of the first drive module 20, and the control feedback module The second output terminal 13 of 10 is connected to the input terminal 31 of the second driving module 30. The buck-boost circuit module 50 includes a first switch 51, a second switch 52, a first diode 54, and a second diode. 55. Inductor 56, capacitor 57, load 58, and power supply 59; the output terminal 22 of the first driving module 20 is connected to one end of the first switch 51, and the output terminal 32 of the second driving module 30 is connected to the second switch 52. One end of the first switch 51 is connected to the positive pole of the power source 59 and one end is connected to the negative pole of the first diode 54; one end of the inductor 56 is connected to the first switch 51 and the other end is connected to one end of the second switch 52 ; The negative pole of the second diode 55 is connected to the input terminal of the voltage sampling module 40, and the positive pole is connected to the inductor 56; one end of the load 58 is connected to the negative pole of the second diode 55, and the other end is connected to One end of the capacitor 57 is connected to the negative pole of the second diode 55, and the other end is connected to the negative pole of the power source 59; one end of the second switch 52 is connected to the negative pole of the power source 59; the first two pole The tube 54 is connected to the negative electrode of the power supply 59; the input terminal 42 of the voltage sampling module 40 is connected to the output terminal 53 of the buck-boost circuit module 50.

Optionally, the first diode 54 and the second diode 55 may be replaced with MOS transistors. MOS tubes are metal-oxide-semiconductor field effect transistors. A bipolar transistor amplifies a small change in the input current and then outputs a large current change at the output. The gain of a bipolar transistor is defined as the ratio of output to input current. Another type of transistor, called a field-effect transistor (FET), converts changes in input voltage into changes in output current. The gain of a FET is defined as the ratio of the change in output current to the change in input voltage. Commonly used MOS transistors are generally divided into N-channel and P-channel, such as N-channel depletion-type MOS transistors, and P-channels are commonly low-voltage MOS transistors.

Using a MOS tube instead of the first diode 54 and the second diode 55 can achieve a bidirectional function, that is, the entire circuit is bidirectionally conductive, and at the same time, the buck-boost circuit module 50 can be controlled to realize the buck-boost function. Using a MOS tube instead of the first diode 54 and the second diode 55 makes the DC step-up and step-down circuit in the embodiment of the present application have more working modes, more flexible use, and more convenient control.

As can be seen from FIG. 2, when the second switch 52 is turned off and the duty ratio of the first switch 51 is greater than 0%, the DC buck-boost circuit in the embodiment of the present application works in a buck mode; when the first switch 51 When it is turned on and the duty ratio of the second switch 52 is greater than 0%, the DC buck-boost circuit works in a boost mode. It can be understood that the duty ratio of the second switch 52 is 0%, that is, the second switch 52 is in the off state, and the duty ratio of the first switch is greater than 0%, that is, when the first switch 51 is in the working state, the DC voltage is stepped up and down. The circuit works in a buck mode; the duty cycle of the first switch 51 is 100%, that is, the first switch 51 is in the on state, and the duty cycle of the second switch 52 is greater than 0%, that is, when the second switch 52 is in the operating state The DC buck-boost circuit works in boost mode. That is, when the DC buck-boost circuit works in the buck mode, the second switch is in the off state, and only the duty cycle of the first switch needs to be determined; when the DC buck-boost circuit works in the boost mode, the first One switch is in the on state, and only the duty cycle of the second switch needs to be determined.

In the embodiment of the present application, the value range of the feedback value may be divided into two numerical intervals, one corresponding to the duty ratio of the first switch 51 in the buck mode, and the other corresponding to the duty ratio of the second switch 52 in the boost mode. Duty cycle; can make the switching speed between boost mode and buck mode faster, and can make the output voltage better meet the demand.

In an optional implementation manner, the range of the feedback value corresponds to the first interval and the second interval, and the control feedback module presets the duty ratio of the first interval and the first switch 51 and the second switch. The corresponding relationship between the duty ratio of 52 and the corresponding relationship between the second interval, the duty ratio of the first switch 51 and the duty ratio of the second switch 52.

The first interval may be a range of feedback values indicating that the DC buck-boost circuit operates in the buck mode, and the second interval may be a range of feedback values indicating that the DC buck-boost circuit operates in the boost mode. For example, the feedback value is in the range of 0-30000. If the feedback value is in the first interval of 0-10000, the DC buck-boost circuit needs to work in the buck mode; if the feedback value is in the second interval of 10001-30000, the DC The buck-boost circuit needs to work in boost mode.

In the embodiment of the present application, the correspondence relationship between the first interval, the duty ratio of the first switch 51 and the duty ratio of the second switch 52, and the duty ratio of the second interval and the first switch 51 The correspondence relationship with the duty ratio of the second switch 52 can quickly determine the duty ratio of the first switch 51 and the duty ratio of the second switch 52, and has high calculation efficiency.

In an optional implementation manner, the duty ratio of the first switch 51 corresponding to the first interval ranges from M% to N%, and the duty ratio of the corresponding second switch 52 is 0%; The M is greater than or equal to 0, and the N is less than or equal to 100.

For example, the duty cycle of the first switch 51 corresponding to the first interval ranges from 0% to 70%, and the duty cycle of the corresponding second switch 52 is 0%. The duty ratio of the second switch 52 is 0%, which indicates that the second switch 52 is in an off state. In the embodiment of the present application, when the second switch 52 is turned off and the duty ratio of the first switch 51 is greater than 0%, the DC buck-boost circuit works in a buck mode. It can be understood that the first interval corresponds to the range of the duty ratio of the first switch 51 in the buck mode, and the first interval corresponding to the duty ratio of the first switch 51 can accurately determine the first corresponding to the feedback value. The duty ratio of the switch 51. Assume that the first interval is from 0 to 10000, and the duty ratio of the corresponding first switch 51 is 0% -100%, and the feedback value is 5100. Then, the duty ratio of the first switch 51 is 51%.

In the embodiment of the present application, by setting the range of the duty ratio of the first switch 51 corresponding to the first interval, the range of the duty ratio when the DC buck-boost circuit works in the buck mode can be accurately determined, which better meets Output voltage requirements.

In an optional implementation manner, when the feedback value is in the first interval, the feedback value is positively related to the duty ratio of the first switch 51.

The mapping relationship between the feedback value and the duty ratio of the first switch 51 may be a linear relationship or a non-linear relationship. The feedback value is positively related to the duty ratio of the first switch 51. It can be understood that the feedback value increases to the duty ratio of the first switch 51. For example, the first feedback value is 100 and the corresponding duty cycle is 1%; the second feedback value is 1000 and the corresponding duty cycle is 5%.

In the embodiment of the present application, the duty ratio of the first switch 51 corresponding to the feedback value can be quickly determined.

In an optional implementation manner, the duty ratio of the second switch 52 corresponding to the second interval ranges from P% to Q%, and the duty ratio of the corresponding first switch 51 is 100%; The P is greater than or equal to 0, and the Q is less than or equal to 100.

For example, the duty ratio of the second switch 52 corresponding to the second interval ranges from 0% to 80%, and the duty ratio of the corresponding first switch 51 is 100%. The duty ratio of the first switch 51 is 100%, which indicates that the first switch 51 is in an on state. In the embodiment of the present application, when the first switch 51 is turned on and the duty ratio of the second switch 52 is greater than 0%, the DC buck-boost circuit works in a boost mode. It can be understood that the second interval corresponds to the range of the duty ratio of the second switch 52 in the boost mode. Through the correspondence between the second interval and the duty ratio of the second switch 52, it is possible to accurately determine the second corresponding to the feedback value. The duty cycle of the switch 52. Assume that the second interval is from 0 to 10000, and the duty cycle of the corresponding second switch 52 is 0% -100%, and the feedback value is 5100. Then, the duty ratio of the second switch 52 is 51%.

In the embodiment of the present application, by setting the range of the duty ratio of the second switch 52 corresponding to the second interval, the range of the duty ratio when the DC buck-boost circuit works in the boost mode can be accurately determined, which better meets Output voltage requirements.

In an optional implementation manner, when the feedback value is in the second interval, the feedback value is positively related to the duty ratio of the second switch 52.

The mapping relationship between the feedback value and the duty ratio of the second switch 52 may be a linear relationship or a non-linear relationship. The feedback value is positively related to the duty ratio of the second switch 525, and it can be understood that the duty ratio increases as the feedback value reaches the second on-off 52. For example, the third feedback value is 100, corresponding to a duty cycle of 1%; the fourth feedback value is 1000, and the corresponding feedback value is 5%.

In the embodiment of the present application, the duty ratio of the second switch 52 corresponding to the feedback value can be quickly determined.

In an optional implementation manner, the step-up and step-down circuit module includes a DC step-down module and a DC step-up module, and the DC step-down module and the DC step-up module are connected in cascade; When the second switch 52 is turned off and the first switch 51 is operating, the step-down function is performed by the DC step-down module. The step-up and step-down circuit module passes the DC when the first switch 51 is turned on and the second switch 52 is operated. The boost module performs a boost function.

The step-up and step-down circuit module shown in FIG. 2 includes a DC step-down module and a DC step-up module, where the DC step-down module and the DC step-up module are cascaded, and uses a common inductor as an energy storage carrier, which is a dual switch Buck and boost combination circuit. As shown in FIG. 2, when the second switch 52 is turned off and the first switch 51 is operated, that is, when the duty ratio of the first switch 515 is greater than 0%, the DC step-down module in the DC step-up and step-down circuit is operated; Turning on 51 and turning off, and the second switch 52 works. That is, when the duty ratio of the second switch 52 is greater than 0%, the DC boost module in the DC step-up / step-down circuit works.

It can be understood that when the duty ratio of the second switch 52 is 0% and the duty ratio of the first switch 51 is greater than 0%, the DC buck-boost circuit works in a buck mode, that is, the DC buck module works; When the duty ratio of the first switch 51 is 100% and the duty ratio of the second switch 52 is greater than 0%, the DC buck-boost circuit works in a boost mode, that is, the DC boost module works.

In the embodiment of the present application, by controlling the duty ratios of the first switch 51 and the second switch 52, the working mode of the DC buck-boost circuit can be quickly switched, and the implementation is simple.

In an optional implementation manner, the control feedback module 10 is a digital signal processor.

Digital Signal Processing (DSP) is suitable for the occasions with high time and algorithm complexity. Using DSP can quickly and accurately calculate the feedback value based on the sampled value, and determine the first switch 51 and the first based on the feedback value. Duty cycle of the two switches 52. In the embodiment of the present application, a DSP is used to calculate the duty ratios of the first switch 51 and the second switch 52, and the calculation speed is fast and the accuracy is high.

The control feedback module 10 mentioned in the embodiment of the present application may include a proportional-integral-derivative (PID) controller. The PID controller is a common feedback loop component in industrial control applications. P, integral unit I and differential unit D are composed. PID control is based on proportional control. Integral control can eliminate steady-state errors. Differential control can speed up the response of large inertia systems and reduce the tendency of overshoot. Parameter tuning of the PID controller is the core content of the control system design. The proportional coefficient, integration time, and derivative time of the PID controller can be determined according to the characteristics of the controlled process. In the embodiment of the present application, the PID controller is used to calculate the feedback value, and the first duty ratio and the second duty ratio are determined according to the value interval in which the feedback value is located. The system has a fast response speed and high accuracy.

In an optional implementation manner, the first pulse signal and the second pulse signal are both pulse width modulation signals; and when the feedback value is in the first interval, the step-up and step-down circuit is configured to execute the above-mentioned Step-down mode of the step-down function; when the feedback value is within the second interval, the step-up and step-down circuit operates in a step-up mode that performs the step-up function; the operation mode of the step-up and step-down circuit is different, and The control modes of the first driving module 20 and the second driving module 30 are different or the corresponding feedback parameters are different.

Both the first pulse signal and the second pulse signal may be rectangular pulses. Figure 3 shows the pulse waveform of a signal period, the pulse width is 1us, and the signal period is 4us. Assuming that the pulse waveform in FIG. 3 is a waveform corresponding to the pulse received by the first switch 51, the duty ratio of the first switch 51 is 0.25. In practical applications, if the signal period is 4us, the control feedback module 10 determines that the duty ratio of the first switch 51 is 0.25, then the control feedback module 10 controls the first drive module 20 to send a 1us width to the first switch 51. Pulse signal.

Step-up and step-down are two different processes. The transfer function of the step-up and step-down modes of the DC buck-boost circuit is different, that is, the transfer functions corresponding to the step-up and step-down are different. It can be understood that step-up and step-down can be implemented using different control methods or different feedback parameters. For example, the DC buck-boost circuit works in a boost mode, and the pulse width modulation circuit uses a first control method to control the first switch 51 and the second switch 52; the DC buck-boost circuit works in a buck mode, and the pulse width modulation circuit The second control method is used to control the first switch 51 and the second switch 52, and the first control method and the second control method are different. At the same time, you can choose a section from the boost mode to the buck mode or from the buck mode to the boost mode for the transition; the transition section can be a parameter gradient or different control methods. Step-up and step-down use different control methods to more accurately adjust the output voltage to the required voltage.

Because the transfer functions of the buck and boost are different, different algorithms can be added to the feedback values corresponding to the duty ratios of the first switch 51 and the second switch 52. In addition, when the buck-boost circuit module 50 works in the boost mode and the buck mode, different feedback parameters can be used to determine the duty ratios of the first switch 51 and the second switch 52, and the output voltage can be adjusted more quickly to the desired value. Required voltage.

In the embodiment of the present application, the on / off of the switch is controlled by a Pulse Width Modulation (PWM) signal, and the implementation is simple.

In an optional implementation manner, the first switch 51 and the second switch 52 are both an insulated gate bipolar transistor (IGBT) or an electric field effect transistor; the range of the feedback value corresponds to The value interval includes a third interval, a transition interval, and a fourth interval. The control feedback module 10 includes a correspondence between the transition interval and the duty cycle of the first switch 51 and the duty cycle of the second switch 52. In a relationship, when the feedback value is in the transition interval, the buck-boost circuit module 50 is in a transition from the boost mode to the buck mode or from the buck mode to the boost Voltage mode transition circuit stage.

The transition circuit stage is a stage between the boost mode and the buck mode. In the transition circuit stage described above, the input voltage and output voltage of the buck-boost circuit module are almost equal. In the above-mentioned transition circuit stage, the DC step-up and step-down circuit can gradually change the duty cycle, period, and pulse width of the PWM, so as to complete the transition faster. Compared with the foregoing embodiment, the third interval and the fourth interval are respectively similar to the first interval and the second interval in the foregoing embodiment, and the numerical interval corresponding to the feedback value in this embodiment further includes a transition interval When the feedback value is in the transition interval, parameters of the first driving module 20 and the second driving module 30 may be changed, so that the first pulse signal sent by the first driving module 20 and the second driving module 20 may be changed. The second pulse signal sent by the driving module 30 is gradual. By setting the transition interval and the parameter gradual change in the transition phase, the transition between step-up and step-down of the circuit can be better realized, so that the circuit has no transitions during the transition phase, and can more quickly and stably be used in the step-up and step-down functions. Between conversions.

In the embodiment of the present application, both the first switch 51 and the second switch 52 may use an insulated gate bipolar transistor or a power field effect transistor, and the switching speed is fast, which can make the DC step-up and step-down circuit quickly realize the step between step-down and step-up. Conversion. Insulated gate bipolar transistors have high operating frequency, small required driving power, small switching loss, and fast switching speed, which can make the DC buck-boost circuit quickly realize the conversion between step-down and step-up. The electric field effect transistor has fast switching speed, simple driving circuit and high working frequency. Power field effect transistor, also known as power field effect transistor, is divided into junction type and insulated gate type. Generally, it mainly refers to MOS type (Metal Oxide Semiconductor) in insulated gate type, referred to as power MOSFET (Power MOSFET) for short. Junction power field effect Transistors are also commonly referred to as Static Induction Transistors (SIT).

The above is only a specific implementation of this application, but the scope of protection of this application is not limited to this. Any person skilled in the art can easily think of various equivalents within the technical scope disclosed in this application. Modifications or replacements, and these modifications or replacements should be covered by the protection scope of this application. Therefore, the protection scope of this application shall be subject to the protection scope of the claims.

Claims

A DC buck-boost circuit, comprising:

A control feedback module, a first driving module, a second driving module, a voltage sampling module, and a step-up and step-down circuit module;

An input terminal of the control feedback module is electrically connected to an output terminal of the voltage sampling module, a first output terminal of the control feedback module is connected to an input terminal of the first drive module, and a second terminal of the control feedback module The output end is connected to the input end of the second driving module; the step-up and step-down circuit module includes a first switch and a second switch, and the output end of the first driving module is connected to one end of the first switch, and The output terminal of the second driving module is connected to one end of the second switch; the input terminal of the voltage sampling module is connected to the output terminal of the buck-boost circuit module;

The voltage sampling module samples the output voltage of the buck-boost circuit module to obtain a sample value of the output voltage, and sends the sampled value of the output voltage to the control feedback module; the control feedback module uses the The feedback value is calculated from the sampled value of the output voltage and the reference value of the output voltage, and the first duty ratio and the second duty ratio are determined according to the value interval in which the feedback value is located. The value corresponding to the value range of the feedback value The interval includes two or more intervals, the first duty cycle is the duty cycle of the first switch, and the second duty cycle is the duty cycle of the second switch; the control feedback The module controls the first driving module to send a first pulse signal to the first switch and the second driving module to send a second pulse signal to the second switch. The first pulse signal is to make the first The duty ratio of a switch is a pulse signal of the first duty ratio, and the second pulse signal is a pulse signal of a duty ratio of the second switch to the second duty ratio.
The DC step-up and step-down circuit according to claim 1, wherein the value interval corresponding to the value range of the feedback value includes a first interval and a second interval, and the control feedback module includes the first interval Correspondence with the duty ratio of the first switch and the duty ratio of the second switch, and the duty ratio of the second interval with the duty ratio of the first switch and the duty ratio of the second switch Corresponding relationship.
The DC buck-boost circuit according to claim 2, wherein the duty ratio of the first switch corresponding to the first interval ranges from M% to N%, and the corresponding second switch The duty cycle is 0%; the M is greater than or equal to 0, and the N is less than or equal to 100.
The DC buck-boost circuit according to claim 3, wherein, in a case where the feedback value is in the first interval, the feedback value is positively related to a duty ratio of the first switch.
The DC step-up and step-down circuit according to claim 3, wherein the duty ratio of the second switch corresponding to the second interval ranges from P% to Q%, and the corresponding first switch The duty cycle is 100%; the P is greater than or equal to 0, and the Q is less than or equal to 100.
The DC buck-boost circuit according to claim 5, wherein, in a case where the feedback value is in the second interval, the feedback value is positively related to a duty ratio of the second switch.
The DC step-up and step-down circuit according to any one of claims 1-6, wherein the step-up and step-down circuit module comprises a DC step-down module and a DC step-up module, the DC step-down module and the DC The step-up and step-down circuit module performs a step-down function through the DC step-down module when the second switch is turned off and the first switch is in operation. When the first switch is turned on and the second switch is operating, a boost function is performed by the DC boost module.
The DC buck-boost circuit according to claim 7, wherein the control feedback module is a digital signal processor.
The DC step-up and step-down circuit according to claim 8, wherein the first pulse signal and the second pulse signal are both pulse-width modulation signals; and the feedback value is within the first interval. In the case, the step-up and step-down circuit operates in a step-down mode that performs the step-down function; and when the feedback value is within the second interval, the step-up and step-down circuit operates in performing the step-up Boost function in boost mode.
The DC buck-boost circuit according to claim 9, wherein the first switch and the second switch are both an insulated gate bipolar transistor or a power field effect transistor; and the range of the feedback value corresponds to The value interval includes a third interval, a transition interval, and a fourth interval, and the control feedback module includes a correspondence between the transition interval and the duty cycle of the first switch and the duty cycle of the second switch. In a case where the feedback value is in the transition interval, the buck-boost circuit module is in a state of transition from the boost mode to the buck mode or from the buck mode to the boost mode. Transition circuit stage.