High-voltage gain Cuk DC-DC converter

Abstract

The utility model provides a high voltage gain Cuk DC-DC (Direct Current-Direct Current) converter. The converter is composed of a Cuk circuit basic module, a switch inductor module, a switch capacitor module, an expansion unit module and a load resistor. Each expansion unit is composed of a diode, an inductor and two capacitors, and input and output gain adjustment of the converter can be achieved by adjusting the number of the expansion units. The switched inductor module is composed of an inductor and two switching tubes, the switched capacitor module is composed of two diodes and two capacitors, and the gain of the converter is further improved by introducing two energy storage elements of the switched inductor and the switched capacitor. In addition, the converter also has the advantages of simple control and drive circuits, low voltage stress of switching devices and the like, and is more suitable for application occasions with larger input and output voltage difference.

Description

Technical Field

[0001] The utility model relates to a high voltage gain boost converter, in particular to a voltage gain Cuk DC-DC converter. Background Art

[0002] The output voltage of renewable energy is usually low. In order to obtain high output voltage in low voltage energy systems, it is urgent to use a boost DC-DC converter. The traditional boost converter has limited voltage gain, large voltage stress of the switch tube, and low converter conversion efficiency. Therefore, the study of high gain converter has important theoretical significance and application value.

[0003] Regarding the structural design of a converter with high gain, relevant technical solutions have been disclosed in the prior art, such as the Chinese utility model patent with announcement number CN215772920U, which discloses "a high-gain flyback converter". The converter is composed of a voltage input source, a switching circuit, a flyback transformer and a boost output circuit. Although the application scheme improves the voltage gain, it contains a flyback transformer, which is large in size, high in cost and complex to control.

[0004] In addition, for the invention with the publication number CN116707308 A, the title is: A multi-port high-gain converter for a photovoltaic storage system, the technical solution has many switch tubes and large losses. Therefore, there is an urgent need for a high-gain and simple-to-control converter. Utility Model Content

[0005] In order to solve the defect of low voltage gain of the existing Cuk DC-DC converter, the utility model proposes a high voltage gain Cuk DC-DC converter based on the Cuk circuit.

[0006] In order to achieve the above requirements, the technical solution adopted by the utility model is:

[0007] A high voltage gain Cuk DC-DC converter, comprising:

[0008] Cuk circuit basic module.

[0009] A switch inductor module is connected to the Cuk circuit basic module.

[0010] A switch capacitor module is connected to the Cuk circuit basic module.

[0011] The expansion unit module is connected to the Cuk circuit basic module.

[0012] Load resistance R o , which is connected to the Cuk circuit basic module, the switch capacitor module, the switch inductor module and the expansion unit module.

[0013] The switching inductor module is composed of a second inductor L2, a first switching tube S1 and a second switching tube S2.

[0014] The connection mode inside the switching inductor module is as follows: the left end of the second inductor L2 is connected to the lower end of the second switch tube S2; the right end of the second inductor L2 is connected to the lower end of the first switch tube S1.

[0015] The switch capacitor module is composed of a second capacitor C2, a first diode D1 and a second diode D2.

[0016] The connection mode inside the switch capacitor module is as follows: the left end of the second capacitor C2 is connected to the cathode of the second diode D2; and the right end of the second capacitor C2 is connected to the lower end of the first diode D1.

[0017] The expansion unit module includes n expansion units, each of which is composed of a boost diode D a , energy storage capacitor C a 、Filter capacitor C b And boost inductor L a constitute.

[0018] The connection mode inside the expansion unit is as follows: the energy storage capacitor C a The right end of the boost diode D a The anode of the boost inductor L a The left end is connected to the filter capacitor C b The upper end of the boost inductor L a The right end is connected.

[0019] The connection mode between the expansion units is as follows: the energy storage capacitor C of the latter expansion unit a The left end of the boost diode D of the previous expansion unit a anode, the energy storage capacitor C of the previous expansion unit a The right end and the boost inductor L of the previous expansion unit a The left end is connected to the boost diode D of the next expansion unit. a The cathode of the previous expansion unit, the boost inductor L a The right end and the filter capacitor C of the previous expansion unit b connected to the upper end.

[0020] The Cuk circuit basic module consists of a DC power supply V in , a first capacitor C1, a third capacitor C3, a first inductor L1, and a third inductor L3.

[0021] The connection mode inside the Cuk circuit basic module is as follows: the DC power supply Vin The positive electrode is connected to the left end of the first inductor L1; the right end of the first inductor L1 is connected to the left end of the first capacitor C1; the right end of the first capacitor C1 is connected to the left end of the third inductor L3; the right end of the third inductor L3 is connected to the upper end of the third capacitor C3.

[0022] The connection mode of the Cuk circuit basic module and the expansion unit module is as follows: the energy storage capacitor C of the first expansion unit in the expansion unit module a The left end of the third inductor L3, the left end of the third inductor L3, and the right end of the first capacitor C1 are connected; the boost diode D of the first expansion unit in the expansion unit module a The cathode of the third inductor L3, the right end of the third inductor L3 and the upper end of the third capacitor C3 are connected.

[0023] The connection mode of the Cuk circuit basic module and the switch inductor module is as follows: the DC power supply V in The negative electrode of the first switch tube S1 and the lower end of the second switch tube S2 are connected to the left end of the second inductor L2; the upper end of the first switch tube S1 and the left end of the first inductor L1 are connected to the DC power supply V in The upper end of the second switch tube S2 is connected to the right end of the first inductor L1.

[0024] The connection method of the Cuk circuit basic module and the switch capacitor module is: the anode of the first diode D1 and the left end of the first capacitor C1 are connected to the right end of the first inductor L1; the anode of the second diode D2 and the right end of the first capacitor C1 are connected to the left end of the third inductor L3.

[0025] The connection mode of the switch inductor module and the switch capacitor module is as follows: the lower end of the first switch tube S1, the right end of the second inductor L2, and the left end of the second capacitor C2 are connected to the cathode of the second diode D2; the upper end of the second switch tube S2, the anode of the first diode D1 and the left end of the first capacitor C1 are connected.

[0026] The connection mode of the switch capacitor module and the expansion unit module is as follows: the energy storage capacitor C of the first expansion unit in the expansion unit module a The left end of is connected to the anode of the second diode D2.

[0027] The load resistance R o The upper end of the filter capacitor C of the last expansion unit in the expansion unit module b The upper end and boost inductor L a The right end is connected to the load resistor R oThe lower end of the expansion unit module and the filter capacitor C of each expansion unit b The lower end of the third capacitor C3, the cathode of the first diode D1, and the right end of the second capacitor C2 are connected.

[0028] The gates of the first switch tube S1 and the second switch tube S2 are connected to a driving controller, and the duty ratios thereof vary between 0 and 1.

[0029] The present invention provides a high voltage gain Cuk DC-DC converter, which has the following beneficial effects:

[0030] 1. The input and output voltage gain is high, and the converter structure is expandable, which can well meet the grid-connected voltage requirements of photovoltaic power generation. Among them: The converter output voltage U O With the input power supply voltage U in The ratio of the voltage gain of the converter is: The voltage stress of the switch tube is: Where D is the duty cycle (i.e., the ratio of the on time to the switching cycle time in a switching cycle), U O is the output voltage, U in The input power supply V in The voltage of the switch tube is Us, which makes it work at a suitable duty cycle D to meet the boost requirements in different occasions.

[0031] 2. The control and drive circuit design is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a circuit diagram of a high voltage gain Cuk DC-DC converter (connected with n expansion units) involved in the utility model;

[0033] Figure 2 This is a circuit diagram of a high voltage gain Cuk DC-DC converter (connected with 2 expansion units) involved in the utility model;

[0034] Figure 3(a) to Figure 3(b) 3(a) is an equivalent circuit diagram of a high voltage gain Cuk DC-DC converter in an embodiment of the utility model in a switching cycle, wherein FIG. 3(a) is an equivalent circuit diagram in working mode 1, and FIG. 3(b) is an equivalent circuit diagram in working mode 2. In the figure, the solid line represents the part of the converter where current flows, and the dotted line represents the part of the converter where no current flows;

[0035] Figure 4 This is a simulation result diagram of a high voltage gain Cuk DC-DC converter (connected with 2 expansion units) involved in the utility model; DETAILED DESCRIPTION

[0036] The utility model is further described in detail below in conjunction with the accompanying drawings.

[0037] refer to Figure 2 Specifically, a high voltage gain Cuk DC-DC converter includes: a Cuk circuit basic module, a switch inductor module, an expansion unit module, a switch capacitor module, a load resistor R o .

[0038] The expansion unit module contains two expansion units, which are composed of a boost diode D a , energy storage capacitor C a 、Filter capacitor C b And boost inductor L a constitute.

[0039] The connection mode inside the expansion unit is: energy storage capacitor C a The right end of the boost diode D a Anode, boost inductor L a The left end is connected to the filter capacitor C b The upper end of the boost inductor L a The right end is connected.

[0040] The switching inductor module is composed of a second inductor L2, a first switching tube S1 and a second switching tube S2.

[0041] The connection mode inside the switch inductor module is as follows: the left end of the second inductor L2 is connected to the lower end of the second switch tube S2; the right end of the second inductor L2 is connected to the lower end of the first switch tube S1.

[0042] The switched capacitor module is composed of a second capacitor C2, a first diode D1 and a second diode D2.

[0043] The connection mode inside the switch capacitor module is as follows: the left end of the second capacitor C2 is connected to the cathode of the second diode D2; and the right end of the second capacitor C2 is connected to the lower end of the first diode D1.

[0044] The basic module of Cuk circuit consists of a DC power supply V in , a first capacitor C1, a third capacitor C3, a first inductor L1, and a third inductor L3.

[0045] The internal connection mode of the Cuk circuit basic module is: DC power supply V in The positive electrode is connected to the left end of the first inductor L1; the right end of the first inductor L1 is connected to the left end of the first capacitor C1; the right end of the first capacitor C1 is connected to the left end of the third inductor L3; the right end of the third inductor L3 is connected to the upper end of the third capacitor C3.

[0046] The connection method of the Cuk circuit basic module and the expansion unit module is as follows: the energy storage capacitor C of the first expansion unit a The left end of the third inductor L3 and the right end of the first capacitor C1 are connected; the boost diode D of the first expansion unit a The cathode of the third inductor L3, the right end of the third inductor L3 and the upper end of the third capacitor C3 are connected.

[0047] The connection method of the Cuk circuit basic module and the switch inductor module is as follows: DC power supply V in The negative electrode of the second switch tube S2 and the lower end of the second inductor L2 are connected; the upper end of the first switch tube S1 and the left end of the first inductor L1 are connected to the DC power supply V in The upper end of the second switch tube S2 is connected to the right end of the first inductor L1.

[0048] The connection method of the Cuk circuit basic module and the switch capacitor module is: the anode of the first diode D1, the left end of the first capacitor C1 and the right end of the first inductor L1 are connected; the anode of the second diode D2, the right end of the first capacitor C1 and the left end of the third inductor L3 are connected.

[0049] The connection method of the switch inductor module and the switch capacitor module is: the lower end of the first switch tube S1, the right end of the second inductor L2, the left end of the second capacitor C2 are connected to the cathode of the second diode D2; the upper end of the second switch tube S2, the anode of the first diode D1 and the left end of the first capacitor C1 are connected.

[0050] The connection method of the switch capacitor module and the expansion unit module is as follows: the energy storage capacitor C of the first expansion unit in the expansion unit module a The left end of is connected to the anode of the second diode D2.

[0051] Load resistance R o The upper end of the filter capacitor C of the second expansion unit b The upper end of the load resistor R o The lower end of the filter capacitor C of each expansion unit b The lower end of the third capacitor C3, the cathode of the first diode D1, and the right end of the second capacitor C2 are connected.

[0052] The gates of the first switch tube S1 and the second switch tube S2 are connected to a driving controller, and their duty ratios (ie, the ratio of the on-time to the switching cycle time in a switching cycle) vary between 0 and 1.

[0053] A high voltage gain Cuk DC-DC converter has two working modes in one switching cycle, namely, the first switch tube S1 and the second switch tube S2 are turned on and off, which are switched to each other. Figure 3(a) to Figure 3(b) shown.

[0054] Working mode 1:

[0055] As shown in FIG3(a), the first switch tube S1 and the second switch tube S2 are turned on, and the first diode D1, the second diode D2, and the boost diodes D in the two gain units are turned on. a are all turned off. At this time, the first inductor L1 and the boost inductor L in the two gain units are a , the third capacitor C3, the filter capacitors C in the two gain units b Charging, the first capacitor C1, the energy storage capacitors C in the two gain units a Discharge; According to Kirchhoff's voltage law, the first inductor L1, the second inductor L2, the third inductor L3, the boost inductor L in the first gain unit a The terminal voltage and the boost inductor L in the second gain unit a As shown below:

[0056]

[0057] Where u L1 is the voltage across the first inductor L1, u in is the DC power supply V in Voltage,u L2 is the voltage across the second inductor L2, u L3 is the voltage across the third inductor L3, u La1 is the voltage across the boost inductor in the first boost unit, u La2 is the voltage across the boost inductor in the second boost unit, and the voltage across the first capacitor C1 and the second capacitor C2 is equal to u C ,u C3 is the voltage across the third capacitor C3, u Ca1 is the voltage across the energy storage capacitor in the first boost unit, u Ca2 is the voltage across the energy storage capacitor in the second boost unit, u Cb1 is the voltage across the filter capacitor in the first boost unit, u Cb2 is the voltage across the filter capacitor in the second boost unit.

[0058] Working mode 2:

[0059] As shown in FIG3(b), the first switch tube S1 and the second switch tube S2 are turned off, and the first diode D1, the second diode D2, and the boost diodes D in the two gain units are turned off. a are all turned on. At this time, the first inductor L1 and the boost inductor L in the two gain units a , the third capacitor C3, the filter capacitors C in the two gain units bDischarge, the first capacitor C1, the energy storage capacitors C in the two gain units a Charging; According to Kirchhoff's voltage law, the first inductor L1, the second inductor L2, the third inductor L3, the boost inductor L in the first gain unit a The terminal voltage and the boost inductor L in the second gain unit a As shown below:

[0060]

[0061] Where u L1 is the voltage across the first inductor L1, u in is the DC power supply V in Voltage,u L2 is the voltage across the second inductor L2, u L3 is the voltage across the third inductor L3, u La1 is the voltage across the boost inductor in the first boost unit, u La2 is the voltage across the boost inductor in the second boost unit, and the voltage across the first capacitor C1 and the second capacitor C2 is equal to u C ,u C3 is the voltage across the third capacitor C3, u Ca1 is the voltage across the energy storage capacitor in the first boost unit, u Ca2 is the voltage across the energy storage capacitor in the second boost unit, u Cb1 is the voltage across the filter capacitor in the first boost unit, u Cb2 is the voltage across the filter capacitor in the second boost unit.

[0062] The volt-second balance formula u L ΔT on =u L ΔT off (u L is the voltage across the inductor, ΔT on is the power switch on time, ΔT off is the power switch off time) is applied to equation (1) and equation (2) to obtain the input voltage u of the converter in this embodiment: in The ratio of the voltage across the filter capacitor connected to the resistor (i.e. the gain M of the converter) is Where D is the duty cycle of the converter (i.e., the ratio of the switch on time to the cycle time in one switching cycle).

[0063] The input and output voltage simulation diagram of a high voltage gain Cuk DC-DC converter is shown in the figure below: Figure 4 As shown; the simulation software used is PSIM, and the simulation conditions are as follows: input voltage V inThe voltage of the first switch tube and the gate of the second switch tube is 10V, and the gate of the first switch tube and the gate of the second switch tube are connected to a square wave signal with a frequency of 50kHZ and a duty cycle of 0.5; the simulated input and output voltage waveforms are as follows Figure 4 As shown, V in is the input voltage, V o is the output voltage V g is the control voltage of the switch tube; Figure 4 It can be seen that the input voltage V in =10V, output voltage V o =90V, the gain of the converter can be calculated as Substitute the duty cycle D = 0.5 into the theoretical analysis of the converter voltage gain formula In the example, it can be obtained that the voltage gain of the converter is M=9, which is consistent with the simulation result. Therefore, the correctness of the high voltage gain Cuk DC-DC converter of this embodiment can be verified.

[0064] The above-mentioned implementation examples of the utility model are merely examples for explaining the utility model, and are not intended to limit the implementation methods of the utility model. For ordinary technicians in the relevant field, other different forms of changes and modifications can be made on the basis of the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solutions of the utility model are still within the scope of protection of the utility model.

Claims

1. A high voltage gain Cuk DC-DC converter, characterized in that: include: Cuk circuit basic module; A switching inductor module connected to the Cuk circuit basic module; A switch capacitor module connected to the Cuk circuit basic module; An expansion unit module, which is connected to the Cuk circuit basic module; Load resistance R o , which is connected to the Cuk circuit basic module, the switch capacitor module, the switch inductor module and the expansion unit module; The Cuk circuit basic module consists of a DC power supply V in , a first capacitor C1, a third capacitor C3, a first inductor L1, and a third inductor L3; The switching inductor module is composed of a second inductor L2, a first switching tube S1 and a second switching tube S2; The connection mode inside the switching inductor module is as follows: the left end of the second inductor L2 is connected to the lower end of the second switch tube S2; the right end of the second inductor L2 is connected to the lower end of the first switch tube S1; The switch capacitor module is composed of a second capacitor C2, a first diode D1 and a second diode D2; The connection mode inside the switch capacitor module is as follows: the left end of the second capacitor C2 is connected to the cathode of the second diode D2; the right end of the second capacitor C2 is connected to the cathode of the first diode D1; The expansion unit module includes n expansion units, each of which is composed of a boost diode D a , energy storage capacitor C a 、Filter capacitor C b And boost inductor L a constitute; The connection mode inside the expansion unit is as follows: the energy storage capacitor C a The right end of the boost diode D a The anode of the boost inductor L a The left end is connected to the filter capacitor C b The upper end of the boost inductor L a The right end is connected; The connection mode between the expansion units is as follows: the energy storage capacitor C of the latter expansion unit a The left end of the boost diode D of the previous expansion unit a anode, the energy storage capacitor C of the previous expansion unit a The right end and the boost inductor L of the previous expansion unit a The left end is connected to the boost diode D of the next expansion unit. a The cathode of the previous expansion unit, the boost inductor L a The right end and the filter capacitor C of the previous expansion unit b connected to the upper end.

2. The high voltage gain Cuk DC-DC converter according to claim 1, characterized in that: The connection method inside the Cuk circuit basic module is: the positive electrode of the DC power supply Vin is connected to the left end of the first inductor L1; the right end of the first inductor L1 is connected to the left end of the first capacitor C1; the right end of the first capacitor C1 is connected to the left end of the third inductor L3; the right end of the third inductor L3 is connected to the upper end of the third capacitor C3.

3. The high voltage gain Cuk DC-DC converter according to claim 1 or 2, characterized in that: The connection mode of the Cuk circuit basic module and the expansion unit module is as follows: the energy storage capacitor C of the first expansion unit in the expansion unit module a The left end of the third inductor L3, the left end of the third inductor L3, and the right end of the first capacitor C1 are connected; the boost diode D of the first expansion unit in the expansion unit module a The cathode of the third inductor L3, the right end of the third inductor L3 and the upper end of the third capacitor C3 are connected.

4. The high voltage gain Cuk DC-DC converter according to claim 1 or 2, characterized in that: The switching inductor module and the switching capacitor module are connected in the following manner: the lower end of the first switch tube S1, the right end of the second inductor L2, the left end of the second capacitor C2 are connected to the cathode of the second diode D2; the upper end of the second switch tube S2, the anode of the first diode D1 and the left end of the first capacitor C1 are connected; The connection mode of the Cuk circuit basic module and the switch inductor module is as follows: the DC power supply V in The negative electrode of the first switch tube S1 and the lower end of the second switch tube S2 are connected to the left end of the second inductor L2; the upper end of the first switch tube S1 and the left end of the first inductor L1 are connected to the DC power supply V in The upper end of the second switch tube S2 is connected to the right end of the first inductor L1; The connection method of the Cuk circuit basic module and the switch capacitor module is: the anode of the first diode D1 and the left end of the first capacitor C1 are connected to the right end of the first inductor L1; the anode of the second diode D2 and the right end of the first capacitor C1 are connected to the left end of the third inductor L3.

5. The high voltage gain Cuk DC-DC converter according to claim 1 or 2, characterized in that: The connection mode of the switch capacitor module and the expansion unit module is as follows: the energy storage capacitor C of the first expansion unit in the expansion unit module a The left end of is connected to the anode of the second diode D2.

6. The high voltage gain Cuk DC-DC converter according to claim 1, 2 or 3, characterized in that: The load resistance R o The upper end of the filter capacitor C of the last expansion unit in the expansion unit module b The upper end of the boost inductor L a The right end is connected to the load resistor R o The lower end of the expansion unit module and the filter capacitor C of each expansion unit b The lower end of the third capacitor C3, the cathode of the first diode D1, and the right end of the second capacitor C2 are connected.

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