A high step-down ratio DC-DC converter and control method thereof

Abstract

The present invention provides a high step-up and step-down ratio DC-DC converter and a control method thereof, comprising a DC power supply, a first diode, a second diode, a first inductor, a second inductor, a third inductor, a first capacitor, a second capacitor, a third capacitor, a first semiconductor switch device, a second semiconductor switch device, a third semiconductor switch device, a fourth semiconductor switch device, a fifth semiconductor switch device, a sixth semiconductor switch device, and a load, wherein the first semiconductor switch device, the second semiconductor switch device, the third semiconductor switch device, the fourth semiconductor switch device, the fifth semiconductor switch device, and the sixth semiconductor switch device are IGBTs or MOSFETs. The present invention further improves the voltage output range by setting a gain unit through the charging and discharging of capacitors and inductors, so that the converter disclosed in the present invention has a higher voltage gain and a wider range of applications.

Description

Technical Field

[0001] The invention belongs to the technical field of voltage conversion, and in particular relates to a high step-down / step-down ratio DC-DC converter and a control method thereof. Background Art

[0002] Buck-boost DC converters are widely used in DC microgrids, new energy vehicles and other fields. For example, when new energy vehicles are charging and discharging, the voltage changes greatly, and a DC converter with a high buck-boost ratio is required to stabilize the output voltage to meet the load power supply requirements. Although the traditional Buck-Boost DC converter can achieve the buck-boost function, it is affected by the circuit parasitic parameters, the buck-boost adjustment range is limited, and the volume and weight are large, so the use scenarios are limited.

[0003] The quadratic Buck-Boost DC converter is a circuit topology in which the voltage gain and duty cycle are quadratically related, and can effectively improve the voltage gain of the output and input. However, the voltage gain of the basic quadratic Buck-Boost DC converter is only the square of the traditional Buck-Boost DC converter, and the improvement of the voltage gain is also very limited. Therefore, it is necessary to improve the quadratic Buck-Boost DC converter. Summary of the invention

[0004] In view of this, the present invention aims to overcome the deficiencies of the above-mentioned problems in the prior art and proposes a high step-down / step-down ratio DC-DC converter and a control method thereof.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] A first aspect of the present invention provides a high step-down / step-down ratio DC-DC converter, comprising a DC power supply, a first diode D1, a second diode D2, a first inductor L1, a second inductor L2, a third inductor L3, a first capacitor C1, a second capacitor C2, a third capacitor C3, a first semiconductor switch device S1, a second semiconductor switch device S2, a third semiconductor switch device S3, a fourth semiconductor switch device S4, a fifth semiconductor switch device S5, a sixth semiconductor switch device S6, and a load R, wherein an anode of the first diode D1 is connected to a positive electrode of the DC power supply, a cathode of the first diode D1 is connected to a first end of the first inductor L1 and a drain of the second semiconductor switch device S2, a second end of the first inductor L1 is connected to a first end of the first capacitor C1 and a drain of the first semiconductor switch device S1, and a second end of the first capacitor C1 is connected to a second semiconductor switch device S2. The source of the second semiconductor switch device S1 is connected to the drain of the third semiconductor switch device S3, the first end of the second inductor L2 is connected to the source of the first semiconductor switch device S1, the source of the sixth semiconductor switch device S6, the first end of the third capacitor C3, the first end of the load R and the cathode of the DC power supply, the second end of the second inductor L2 is connected to the source of the third semiconductor switch device S3 and the source of the fourth semiconductor switch device S4, the first end of the second capacitor C2 is connected to the drain of the fourth semiconductor switch device S4 and the drain of the fifth semiconductor switch device S5, the second end of the second capacitor C2 is connected to the second end of the third inductor L3 and the drain of the sixth semiconductor switch device S6, the first end of the third inductor L3 is connected to the source of the fifth semiconductor switch device S5 and the cathode of the second diode D2, and the anode of the second diode D2 is connected to the second end of the third capacitor C3 and the second end of the load R.

[0007] Further, the first semiconductor switch device S1, the second semiconductor switch device S2, the third semiconductor switch device S3, the fourth semiconductor switch device S4, the fifth semiconductor switch device S5 and the sixth semiconductor switch device S6 are IGBTs or MOSFETs.

[0008] Furthermore, the first capacitor C1, the second capacitor C2 and the third capacitor C3 are all polarized capacitors.

[0009] Further, the switching frequencies of the first semiconductor switch device S1, the second semiconductor switch device S2, the third semiconductor switch device S3, the fourth semiconductor switch device S4, the fifth semiconductor switch device S5 and the sixth semiconductor switch device S6 are f s , the switching period is T s , T s =1 / f sThe duty cycle of the first semiconductor switch device S1, the third semiconductor switch device S3 and the fifth semiconductor switch device S5 is D, and the duty cycle of the second semiconductor switch device S2, the fourth semiconductor switch device S4 and the sixth semiconductor switch device S6 is (1-D).

[0010] A second aspect of the present invention provides a high step-down / step-down ratio DC-DC converter and a control method thereof, comprising: dividing into two working modes according to the on and off of semiconductor switch devices: working in a first mode when the first semiconductor switch device S1, the third semiconductor switch device S3 and the fifth semiconductor switch device S5 are turned on, and the second semiconductor switch device S2, the fourth semiconductor switch device S4 and the sixth semiconductor switch device S6 are turned off; working in a second mode when the first semiconductor switch device S1, the third semiconductor switch device S3 and the fifth semiconductor switch device S5 are turned off, and the second semiconductor switch device S2, the fourth semiconductor switch device S4 and the sixth semiconductor switch device S6 are turned on; the working interval of the first mode is DT S , the working range of the second mode is (1-D)T S ;

[0011] When working in the first mode, the DC power supply provides energy to the first inductor L1 via the first diode D1 and the first semiconductor switch device S1, the first capacitor C1 provides energy to the second inductor L2 via the first semiconductor switch device S1 and the third semiconductor switch device S3, the second capacitor C2 provides energy to the third inductor L3 via the fifth semiconductor switch device S5, and the third capacitor C3 directly provides energy to the load, then:

[0012] ;

[0013] Vin is the voltage of the DC power supply, is the voltage of the first inductor L1, is the voltage of the second inductor L2, is the voltage of the third inductor L3, is the output voltage;

[0014] When working in the second mode, the first inductor L1 provides energy to the first capacitor C1 via the second semiconductor switch device S2, the second inductor L2 provides energy to the second capacitor C2 via the fourth semiconductor switch device S4 and the sixth semiconductor switch device S6, and the third inductor L3 provides energy to the third capacitor C3 and the load via the sixth semiconductor switch device S6, then:

[0015] ;

[0016] is the voltage of the first capacitor C1, is the voltage of the second capacitor C2, is the voltage of the third capacitor C3;

[0017] According to the volt-second balance characteristics of the first inductor L1, the second inductor L2 and the third inductor L3, it can be obtained that:

[0018] ;

[0019] Combining the above equations, we can get:

[0020] ;

[0021] Then the voltage gain G of the converter is:

[0022] .

[0023] Compared with the prior art, the high step-down / step-down ratio DC-DC converter and the control method thereof described in the present invention have the following advantages:

[0024] The present invention further improves the voltage output range by setting a gain unit through the charging and discharging effects of capacitors and inductors, so that the converter disclosed in the present invention has a higher voltage gain and a wider range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0026] Figure 1 A circuit topology diagram of a high step-down / step-down ratio DC-DC converter of the present invention;

[0027] Figure 2 A schematic diagram of a control method for a high step-down / step-down ratio DC-DC converter according to the present invention;

[0028] Figure 3 A schematic diagram of a high step-down / step-down ratio DC-DC converter of the present invention operating in a first mode;

[0029] Figure 4 A schematic diagram of a high step-down / step-down ratio DC-DC converter of the present invention operating in a second mode;

[0030] Figure 5 The figure is a curve diagram showing the change of gain with duty cycle of a high step-down / step-down ratio DC-DC converter of the present invention. DETAILED DESCRIPTION

[0031] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0032] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0033] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0034] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0035] like Figure 1As shown, the present invention proposes a high step-down ratio DC-DC converter, including a DC power supply, a first diode D1, a second diode D2, a first inductor L1, a second inductor L2, a third inductor L3, a first capacitor C1, a second capacitor C2, a third capacitor C3, a first semiconductor switch device S1, a second semiconductor switch device S2, a third semiconductor switch device S3, a fourth semiconductor switch device S4, a fifth semiconductor switch device S5, a sixth semiconductor switch device S6, and a load R, wherein the anode of the first diode D1 is connected to the positive electrode of the DC power supply, the cathode of the first diode D1 is connected to the first end of the first inductor L1 and the drain of the second semiconductor switch device S2, the second end of the first inductor L1 is connected to the first end of the first capacitor C1 and the drain of the first semiconductor switch device S1, and the second end of the first capacitor C1 is connected to the The source is connected to the drain of the third semiconductor switch device S3, the first end of the second inductor L2 is connected to the source of the first semiconductor switch device S1, the source of the sixth semiconductor switch device S6, the first end of the third capacitor C3, the first end of the load R and the cathode of the DC power supply, the second end of the second inductor L2 is connected to the source of the third semiconductor switch device S3 and the source of the fourth semiconductor switch device S4, the first end of the second capacitor C2 is connected to the drain of the fourth semiconductor switch device S4 and the drain of the fifth semiconductor switch device S5, the second end of the second capacitor C2 is connected to the second end of the third inductor L3 and the drain of the sixth semiconductor switch device S6, the first end of the third inductor L3 is connected to the source of the fifth semiconductor switch device S5 and the cathode of the second diode D2, and the anode of the second diode D2 is connected to the second end of the third capacitor C3 and the second end of the load R.

[0036] In the embodiment of the present invention, the first semiconductor switch device S1, the second semiconductor switch device S2, the third semiconductor switch device S3, the fourth semiconductor switch device S4, the fifth semiconductor switch device S5 and the sixth semiconductor switch device S6 are IGBTs or MOSFETs.

[0037] In the embodiment of the present invention, the first capacitor C1 , the second capacitor C2 and the third capacitor C3 are all polarized capacitors.

[0038] In the embodiment of the present invention, the switching frequency of the first semiconductor switch device S1, the second semiconductor switch device S2, the third semiconductor switch device S3, the fourth semiconductor switch device S4, the fifth semiconductor switch device S5 and the sixth semiconductor switch device S6 is f s , the switching period is T s , T s =1 / f sThe duty cycle of the first semiconductor switch device S1, the third semiconductor switch device S3 and the fifth semiconductor switch device S5 is D, and the duty cycle of the second semiconductor switch device S2, the fourth semiconductor switch device S4 and the sixth semiconductor switch device S6 is (1-D).

[0039] like Figure 2 As shown, a high step-down ratio DC-DC converter in an embodiment of the present invention is divided into two working modes according to the on and off of semiconductor switch devices. The first semiconductor switch device S1, the third semiconductor switch device S3 and the fifth semiconductor switch device S5 work in the first mode when they are turned on, and the second semiconductor switch device S2, the fourth semiconductor switch device S4 and the sixth semiconductor switch device S6 work in the second mode when they are turned on. Among them, the working interval of the first mode is DT S , the working range of the second mode is (1-D)T S .

[0040] First mode: Figure 3 As shown, the first semiconductor switch device S1, the third semiconductor switch device S3, and the fifth semiconductor switch device S5 are turned on, and the second semiconductor switch device S2, the fourth semiconductor switch device S4, and the sixth semiconductor switch device S6 are turned off. At this time, the DC power supply provides energy to the first inductor L1 via the first diode D1 and the first semiconductor switch device S1, the first capacitor C1 provides energy to the second inductor L2 via the first semiconductor switch device S1 and the third semiconductor switch device S3, the second capacitor C2 provides energy to the third inductor L3 via the fifth semiconductor switch device S5, and the third capacitor C3 directly provides energy to the load.

[0041] Working in the first mode, there are:

[0042] ;

[0043] Working in the second mode, such as Figure 4 As shown, the second semiconductor switch device S2, the fourth semiconductor switch device S4, and the sixth semiconductor switch device S6 are turned on, and the first semiconductor switch device S1, the third semiconductor switch device S3, and the fifth semiconductor switch device S5 are turned off. At this time, the first inductor L1 provides energy to the first capacitor C1 via the second semiconductor switch device S2, the second inductor L2 provides energy to the second capacitor C2 via the fourth semiconductor switch device S4 and the sixth semiconductor switch device S6, and the third inductor L3 provides energy to the third capacitor C3 and the load via the sixth semiconductor switch device S6.

[0044] In working mode 2, there are:

[0045] ;

[0046] Among them, Vin is the voltage of the DC power supply, is the voltage of the first inductor L1, is the voltage of the second inductor L2, is the voltage of the third inductor L3, is the voltage of the first capacitor C1, is the voltage of the second capacitor C2, is the voltage of the third capacitor C3, ie, the output voltage V0.

[0047] The voltage gain of a high step-down / step-down ratio DC-DC converter in an embodiment of the present invention is analyzed below.

[0048] like Figure 5 As shown, when the converter is in a steady state, the switching period of the first semiconductor switch device S1, the second semiconductor switch device S2, the third semiconductor switch device S3, the fourth semiconductor switch device S4, the fifth semiconductor switch device S5 and the sixth semiconductor switch device S6 is T S The duty cycle of the first semiconductor switch device S1, the third semiconductor switch device S3 and the fifth semiconductor switch device S5 is D, and the duty cycle of the second semiconductor switch device S2, the fourth semiconductor switch device S4 and the sixth semiconductor switch device S6 is (1-D), that is, the duration of working in the first mode is DT S , the duration of working in the second mode is (1-D)T S According to the volt-second balance characteristics of the first inductor L1, the second inductor L2 and the third inductor L3, it can be obtained that:

[0049] ;

[0050] Combining the above equations, we can get:

[0051] ;

[0052] Then the voltage gain of the high step-up / step-down ratio DC-DC converter can be obtained. for:

[0053] ;

[0054] It can be seen from the above derivation that, compared with the traditional Buck-Boost DC converter and the basic quadratic Buck-Boost DC converter, the high step-up and step-down ratio DC-DC converter of the present invention improves the voltage gain, thereby expanding the output voltage range, and can select the appropriate voltage gain according to the actual application scenario, making it more flexible.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A high step-down / step-down ratio DC-DC converter, characterized in that: The invention comprises a DC power supply, a first diode D1, a second diode D2, a first inductor L1, a second inductor L2, a third inductor L3, a first capacitor C1, a second capacitor C2, a third capacitor C3, a first semiconductor switch device S1, a second semiconductor switch device S2, a third semiconductor switch device S3, a fourth semiconductor switch device S4, a fifth semiconductor switch device S5, a sixth semiconductor switch device S6, and a load R, wherein an anode of the first diode D1 is connected to a positive electrode of the DC power supply, a cathode of the first diode D1 is connected to a first end of the first inductor L1 and a drain of the second semiconductor switch device S2, a second end of the first inductor L1 is connected to a first end of the first capacitor C1 and a drain of the first semiconductor switch device S1, a second end of the first capacitor C1 is connected to a source of the second semiconductor switch device S2 and a drain of the third semiconductor switch device The first end of the second inductor L2 is connected to the source of the first semiconductor switch device S1, the source of the sixth semiconductor switch device S6, the first end of the third capacitor C3, the first end of the load R and the cathode of the DC power supply, the second end of the second inductor L2 is connected to the source of the third semiconductor switch device S3 and the source of the fourth semiconductor switch device S4, the first end of the second capacitor C2 is connected to the drain of the fourth semiconductor switch device S4 and the drain of the fifth semiconductor switch device S5, the second end of the second capacitor C2 is connected to the second end of the third inductor L3 and the drain of the sixth semiconductor switch device S6, the first end of the third inductor L3 is connected to the source of the fifth semiconductor switch device S5 and the cathode of the second diode D2, and the anode of the second diode D2 is connected to the second end of the third capacitor C3 and the second end of the load R; The control method of the converter specifically includes: There are two working modes according to the on and off of the semiconductor switch device: the first semiconductor switch device S1, the third semiconductor switch device S3 and the fifth semiconductor switch device S5 are turned on, and the second semiconductor switch device S2, the fourth semiconductor switch device S4 and the sixth semiconductor switch device S6 are turned off to work in the first mode; the first semiconductor switch device S1, the third semiconductor switch device S3 and the fifth semiconductor switch device S5 are turned off, and the second semiconductor switch device S2, the fourth semiconductor switch device S4 and the sixth semiconductor switch device S6 are turned on to work in the second mode; the working interval of the first mode is DT S , the working range of the second mode is (1-D)T S ; When working in the first mode, the DC power supply provides energy to the first inductor L1 via the first diode D1 and the first semiconductor switch device S1, the first capacitor C1 provides energy to the second inductor L2 via the first semiconductor switch device S1 and the third semiconductor switch device S3, the second capacitor C2 provides energy to the third inductor L3 via the fifth semiconductor switch device S5, and the third capacitor C3 directly provides energy to the load, then: V in is the voltage of the DC power supply, is the voltage of the first inductor L1, is the voltage of the second inductor L2, is the voltage of the third inductor L3, V0 is the output voltage; When working in the second mode, the first inductor L1 provides energy to the first capacitor C1 via the second semiconductor switch device S2, the second inductor L2 provides energy to the second capacitor C2 via the fourth semiconductor switch device S4 and the sixth semiconductor switch device S6, and the third inductor L3 provides energy to the third capacitor C3 and the load via the sixth semiconductor switch device S6, then: is the voltage of the first capacitor C1, is the voltage of the second capacitor C2, is the voltage of the third capacitor C3; According to the volt-second balance characteristics of the first inductor L1, the second inductor L2 and the third inductor L3, it can be obtained that: Combining the above equations, we can get: Then the voltage gain G of the converter is:

2. A high step-down / step-down ratio DC-DC converter according to claim 1, characterized in that: The first semiconductor switch device S1 , the second semiconductor switch device S2 , the third semiconductor switch device S3 , the fourth semiconductor switch device S4 , the fifth semiconductor switch device S5 and the sixth semiconductor switch device S6 are IGBTs or MOSFETs.

3. The high step-down / boost ratio DC-DC converter according to claim 1, characterized in that: The first capacitor C1, the second capacitor C2 and the third capacitor C3 are all polarized capacitors.

4. The high step-down / boost ratio DC-DC converter according to claim 1, characterized in that: The switching frequency of the first semiconductor switch device S1, the second semiconductor switch device S2, the third semiconductor switch device S3, the fourth semiconductor switch device S4, the fifth semiconductor switch device S5 and the sixth semiconductor switch device S6 is f s , the switching period is T s , T s =1 / f s The duty cycle of the first semiconductor switch device S1, the third semiconductor switch device S3 and the fifth semiconductor switch device S5 is D, and the duty cycle of the second semiconductor switch device S2, the fourth semiconductor switch device S4 and the sixth semiconductor switch device S6 is (1-D).

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