A hybrid boost switching power converter and a control method thereof

Abstract

The application discloses a hybrid boost switching power supply converter and a control method thereof, and specifically comprises a first switching device S1, a second switching device S2, a third switching device S3, a fourth switching device S4, a fifth switching device S5, a sixth switching device S6, a first flying capacitor C F1 , a second flying capacitor C F2 , and an inductor L. Compared with the prior art, the application can effectively reduce inductor direct current and inductor ripple, improve conduction loss, realize high conversion ratio and high efficiency, increase load capacity, reduce switching voltage stress, reduce chip area, and avoid complex control circuit by adding two flying capacitors.

Description

Technical Field

[0001] This invention relates to the fields of electronic technology and chip technology, and more specifically, to a hybrid boost switching power converter and its control method. Background Technology

[0002] In recent years, with the increasing use of battery-powered devices, high-efficiency hybrid boost switching power converters have become a research hotspot, widely used in power management integrated circuits, such as battery chargers, LCD bias circuits, and MiniLED driver circuits. Especially in emerging LED display applications, boost power converters are typically required to have high voltage conversion ratios. Specifically, MiniLEDs integrate a large number of diodes connected in series, requiring the LED driver circuit to operate at low input voltages. IN Provides high output voltage V under conditions of (3.3V~6V). OUT (25V~30V). Furthermore, the entire MiniLED array consists of dozens of MiniLEDs, meaning that the LED driver circuit must also possess excellent load-carrying capacity under high voltage output conditions. Therefore, next-generation display technology applications require hybrid boost switching power converters to not only possess the high efficiency advantages of hybrid power converters, but also provide high voltage conversion ratios and large drive current capabilities.

[0003] Traditional dual-switch (2S) boost converters have a simple structure, are easy to control, and can achieve a wide voltage conversion ratio. However, its main drawbacks include: high inductance DC current, large inductance ripple, low efficiency, and poor transient response due to the presence of a zero point in the right half-plane.

[0004] A hybrid boost DC-DC converter is disclosed in the prior art. Compared with traditional boost switching power supply converters, this converter achieves higher efficiency and reduced inductor ripple by adding a capacitor and a switch, thus reducing inductor current and eliminating the need for complex control circuitry. Although this structure makes it easier to achieve a high conversion ratio compared to traditional boost converters, the improvement in inductor current and switching voltage stress is not significant, resulting in greater inductor parasitic resistance losses and switching conduction losses, and the efficiency still needs to be improved. In addition, this structure requires high-voltage processes for fabrication, which increases the chip manufacturing cost and difficulty.

[0005] Therefore, considering the above requirements and the shortcomings of existing technologies such as weak driving capability, large inductor parasitic resistance loss and switching conduction loss, this application proposes a hybrid boost switching power converter and its control method. Summary of the Invention

[0006] This invention provides a hybrid boost switching power converter and its control method. By adding two flying capacitors, the DC current and inductor ripple of the inductor can be effectively reduced, the conduction loss can be improved, the conversion ratio and efficiency can be achieved, and the load capacity can be increased. At the same time, the switching voltage stress is reduced, and the lower voltage stress can reduce the chip area. It does not require adding too many operating states and avoids complex control circuits.

[0007] The primary objective of this invention is to solve the aforementioned technical problems. The technical solution of this invention is as follows:

[0008] The first aspect of this invention provides a hybrid boost switching power converter, comprising: a first switching device S1, a second switching device S2, a third switching device S3, a fourth switching device S4, a fifth switching device S5, a sixth switching device S6, and a first flying capacitor C. F1 Second flying capacitor C F2 and inductor L, where the input voltage V in The negative terminal is grounded, and the positive terminal is connected to the drain of the second switching device S2, the drain of the fourth switching device S4, and one end of the inductor L, respectively. The other end of the inductor L is connected to the drain of the first switching device S1 and the first flying capacitor C, respectively. F1 One end, the first flying capacitor C F1 The other end is connected to the source of the third switching device S3 and the drain of the sixth switching device S6, respectively. The drain of the third switching device S3 is connected to the source of the fourth switching device S4 and the second capacitor C, respectively. F2 One end, the second flying capacitor C F2 The other end is connected to the source of the second switching device S2 and the drain of the fifth switching device S5, respectively, and the source of the sixth switching device S6 outputs voltage V. out and connected to the load capacitor C out One end; where the load capacitance C out The other end, the source of the first switching device S1 and the source of the fifth switching device S5 are both grounded.

[0009] The use of flying capacitors is due to their energy storage function. Through the charging and discharging of flying capacitors, energy is stored and transferred to inductors or outputs. Capacitors have the advantage of higher energy density than other passive devices.

[0010] Furthermore, according to the first flying capacitor C F1 and load capacitance C out The DC current I flowing through the inductor L can be obtained using the law of conservation of charge. L :

[0011]

[0012] Among them, IC1 Indicates the first flying capacitor C F1 The current; I LOAD This indicates the load current flowing through the output terminal. The load is usually a load current source or a load resistor.

[0013] Furthermore, the maximum voltage stress of the first switching device S1 is V. out -2V in The maximum voltage stress of the second switching device S2 is V. out -2V in The maximum voltage stress of the third switching device S3 is V. in The maximum voltage stress of the fourth switching device S4 is V. out -2V in The maximum voltage stress of the fifth switching device S5 is V. in The maximum voltage stress of the sixth switching device S6 is V. in .

[0014] Furthermore, the first flying capacitor C F1 Second Flying Capacitor C F2 The capacitance value is 4.7μF.

[0015] Furthermore, the inductance value of the inductor L is 4.7 μH.

[0016] The second aspect of this invention provides a control method for a hybrid boost switching power converter. By adjusting the logic control signals of the switching devices, the duty cycle of the switching control signals is changed. When the duty cycle is D, the circuit is in a first state, controlling the first switching device S1, the second switching device S2, and the third switching device S3 to be turned on, and controlling the fourth switching device S4, the fifth switching device S5, and the sixth switching device S6 to be turned off; at this time, the second flying capacitor C... F2 Discharge, inductor L and first capacitor C F1 Charging; where 0 < D < 1.

[0017] The duty cycle of the switch control signal represents the conduction time of the switching device.

[0018] Furthermore, based on the duty cycle, the voltage conversion ratio M can be obtained, and its mathematical expression is as follows:

[0019] DV IN +(1-D)(3V IN -V OUT ) = 0

[0020]

[0021] Where D represents the duty cycle of the switch control signal; V inIndicates input voltage; V out This indicates the output voltage.

[0022] Among them, the higher the voltage conversion ratio, the higher the duty cycle D, and thus the longer the duration. The charging duration of the flying capacitor is proportional to the duty cycle D, so as to ensure excellent driving capability under high voltage conversion ratio.

[0023] The third aspect of this invention provides a control method for a hybrid boost switching power converter. By adjusting the logic control signals of the switching devices, the duty cycle of the switching control signals is changed. When the duty cycle is 1-D, the circuit is in a second state, controlling the fourth switching device S4, the fifth switching device S5, and the sixth switching device S6 to conduct, and controlling the first switching device S1, the second switching device S2, and the third switching device S3 to cut off. At this time, the inductor L and the first flying capacitor C... F1 Discharge to supply power to the load, second capacitor C F2 Connected to input voltage V in Charge; where 0 < D < 1.

[0024] Furthermore, based on the duty cycle, the voltage conversion ratio M can be obtained, and its mathematical expression is as follows:

[0025] DV IN +(1-D)(3V IN -V OUT ) = 0

[0026]

[0027] Where D represents the duty cycle of the switch control signal; V in Indicates input voltage; V out This indicates the output voltage.

[0028] Among them, as the voltage conversion ratio is higher, the duty cycle D is higher, resulting in a longer state duration. The charging duration of the flying capacitor is proportional to the duty cycle D, so as to ensure excellent driving capability under high voltage conversion ratio.

[0029] The principle of adjusting the duty cycle of the switch control signal is to input the logic signal of PWM control.

[0030] Furthermore, the specific method for calculating the duty cycle is as follows:

[0031]

[0032] Among them, t ON This indicates the time during which the switching control signals S1, S2, and S3 are at a high level, and the time during which the switching control signals S4, S5, and S6 are at a low level in each cycle; t OFFThis indicates the time during which the switching control signals S1, S2, and S3 are at a low level and the time during which the switching control signals S4, S5, and S6 are at a high level in each cycle; T is the total time of the switching control signals within one working cycle.

[0033] Specifically, by adjusting the logic control signal of the switching devices to change the duty cycle D, the conduction time of the six switching devices is adjusted, thereby affecting the charging and discharging time of the inductor and capacitor to achieve a specific voltage conversion ratio.

[0034] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0035] This invention provides a hybrid boost switching power converter and its control method. By using two flying capacitors, the DC current and inductor ripple of the inductor can be effectively reduced, the conduction loss can be improved, the conversion ratio and efficiency can be achieved, and the load capacity can be increased. At the same time, the switching voltage stress is reduced, and the lower voltage stress can reduce the chip area. It does not require adding too many operating states and avoids complex control circuits. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of a hybrid boost switching power converter according to the present invention.

[0037] Figure 2 This is a circuit diagram of one embodiment of the control method for a hybrid boost switching power converter of the present invention.

[0038] Figure 3 This is a circuit diagram of one embodiment of the control method for a hybrid boost switching power converter of the present invention.

[0039] Figure 4 This is a schematic diagram of the signal timing of the control switching device in one embodiment of the control method for a hybrid boost switching power converter of the present invention.

[0040] Figure 5 This is a schematic diagram of a traditional boost inductor converter.

[0041] Figure 6 This is a schematic diagram of the 3S hybrid boost converter.

[0042] Figure 7 This is a graph showing the inductor current ratio of the present invention compared to traditional boost inductor converters and 3S hybrid boost converters.

[0043] Figure 8 This is a graph showing the inductor current ripple ratio of the present invention compared with traditional boost inductor converters and 3S hybrid boost converters. Detailed Implementation

[0044] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0045] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0046] Example 1

[0047] like Figure 1 As shown, the present invention provides a hybrid boost switching power converter, comprising: a first switching device S1, a second switching device S2, a third switching device S3, a fourth switching device S4, a fifth switching device S5, a sixth switching device S6, and a first flying capacitor C. F1 Second flying capacitor C F2 and inductor L, where the input voltage V in The negative terminal is grounded, and the positive terminal is connected to the drain of the second switching device S2, the drain of the fourth switching device S4, and one end of the inductor L, respectively. The other end of the inductor L is connected to the drain of the first switching device S1 and the first flying capacitor C, respectively. F1 One end, the first flying capacitor C F1 The other end is connected to the source of the third switching device S3 and the drain of the sixth switching device S6, respectively. The drain of the third switching device S3 is connected to the source of the fourth switching device S4 and the second capacitor C, respectively. F2 One end, the second flying capacitor C F2 The other end is connected to the source of the second switching device S2 and the drain of the fifth switching device S5, respectively, and the source of the sixth switching device S6 outputs voltage V. out and connected to the load capacitor C out One end; where the load capacitance C out The other end, the source of the first switching device S1 and the source of the fifth switching device S5 are both grounded.

[0048] The use of flying capacitors is due to their energy storage function. Through the charging and discharging of flying capacitors, energy is stored and transferred to inductors or outputs. Capacitors have the advantage of higher energy density than other passive devices.

[0049] Furthermore, according to the first flying capacitor C F1 and load capacitance C out The DC current I flowing through the inductor L can be obtained using the law of conservation of charge. L :

[0050]

[0051] Among them, I C1 Indicates the first flying capacitor C F1 The current; I LOAD This indicates the load current flowing through the output terminal. The load is usually a load current source or a load resistor.

[0052] Furthermore, as shown in Table 1, the maximum voltage stress of the first switching device S1 is V. out -2V in The maximum voltage stress of the second switching device S2 is V. out -2V in The maximum voltage stress of the third switching device S3 is V. in The maximum voltage stress of the fourth switching device S4 is V. out -2V in The maximum voltage stress of the fifth switching device S5 is V. in The maximum voltage stress of the sixth switching device S6 is V. in .

[0053] Switching devices S1 S2 S3 S4 S5 S6 Voltage stress <![CDATA[V OUT -2V IN ]]> <![CDATA[V OUT -2V IN ]]> <![CDATA[V IN ]]> <![CDATA[V OUT -2V IN ]]> <![CDATA[V IN ]]> <![CDATA[V IN ]]>

[0054] Table 1 Voltage Stress Table for Switching Devices

[0055] Among them, such as Figure 6 Table 2 shows the voltage stress of the switching devices in the 3S hybrid boost converter proposed by Si-Yi Li. It can be seen that the switching voltage stress in the structure of the present invention is smaller. The lower voltage stress can reduce the chip area used and save manufacturing costs.

[0056] Switching devices S1 S2 S3 Voltage stress <![CDATA[V OUT -V in ]]> <![CDATA[V OUT -V in ]]> <![CDATA[V OUT -V in ]]>

[0057] Table 2. Switching Device Voltage Stress Table for the 3S Hybrid Boost Converter Proposed by Si-Yi Li

[0058] Furthermore, the first flying capacitor C F1 Second Flying Capacitor C F2 The capacitance value is 4.7μF.

[0059] Furthermore, the inductance value of the inductor L is 4.7 μH.

[0060] A second aspect of this invention provides a control method for a hybrid boost switching power supply converter, which changes the duty cycle of the switching control signal by adjusting the logic control signal of the switching device, such as... Figure 2As shown, when the duty cycle is D, the circuit is in the first state, controlling the first switching device S1, the second switching device S2, and the third switching device S3 to conduct, and controlling the fourth switching device S4, the fifth switching device S5, and the sixth switching device S6 to cut off; at this time, the second flying capacitor C F2 Discharge, inductor L and first capacitor C F1 Charging; where 0 < D < 1.

[0061] Among them, such as Figure 4 As shown, the duty cycle of the switch control signal represents the conduction time of the switching device.

[0062] Furthermore, based on the duty cycle, the voltage conversion ratio M can be obtained, and its mathematical expression is as follows:

[0063] DV IN +(1-D)(3V IN -V OUT ) = 0

[0064]

[0065] Where D represents the duty cycle of the switch control signal; V in Indicates input voltage; V out This indicates the output voltage.

[0066] Among them, the higher the voltage conversion ratio, the higher the duty cycle D, and thus the longer the duration. The charging duration of the flying capacitor is proportional to the duty cycle D, so as to ensure excellent driving capability under high voltage conversion ratio.

[0067] A third aspect of this invention provides a control method for a hybrid boost switching power supply converter, which changes the duty cycle of the switching control signal by adjusting the logic control signal of the switching device, such as... Figure 3 As shown, when the duty cycle is 1-D, the circuit is in the second state, controlling the fourth switch S4, the fifth switch S5, and the sixth switch S6 to conduct, and controlling the first switch S1, the second switch S2, and the third switch S3 to cut off; at this time, the inductor L and the first flying capacitor C F1 Discharge to supply power to the load, second capacitor C F2 Connected to input voltage V in Charge; where 0 < D < 1.

[0068] Furthermore, based on the duty cycle, the voltage conversion ratio M can be obtained, and its mathematical expression is as follows:

[0069] DV IN +(1-D)(3V IN -V OUT ) = 0

[0070]

[0071] Where D represents the duty cycle of the switch control signal; V in Indicates input voltage; V out This indicates the output voltage.

[0072] Among them, as the voltage conversion ratio is higher, the duty cycle D is higher, resulting in a longer state duration. The charging duration of the flying capacitor is proportional to the duty cycle D, so as to ensure excellent driving capability under high voltage conversion ratio.

[0073] Among them, such as Figure 4 As shown, the principle of adjusting the duty cycle of the switch control signal is to input the logic signal of PWM control.

[0074] Furthermore, the specific method for calculating the duty cycle is as follows:

[0075]

[0076] Among them, t ON This indicates the time during which the switching control signals S1, S2, and S3 are at a high level, and the time during which the switching control signals S4, S5, and S6 are at a low level in each cycle; t OFF This indicates the time during which the switching control signals S1, S2, and S3 are at a low level and the time during which the switching control signals S4, S5, and S6 are at a high level in each cycle; T is the total time of the switching control signals within one working cycle.

[0077] Specifically, by adjusting the logic control signal of the switching devices to change the duty cycle D, the conduction time of the six switching devices is adjusted, thereby affecting the charging and discharging time of the inductor and capacitor to achieve a specific voltage conversion ratio.

[0078] Example 2

[0079] Based on the above embodiment 1, combined with Figures 5-7 This embodiment compares the differences between the present invention and traditional boost inductor converters and 3S hybrid boost converters, and analyzes the inductor current ratio.

[0080] The structure of a traditional boost inductor converter is as follows: Figure 5 As shown, the structure of the 3S hybrid boost converter proposed by Si-Yi Li is as follows: Figure 6 As shown, the 3S boost converter structure has two operating states. In state one, the duty cycle is D. 3SIn state two, switching devices S1 and S2 are on, and S3 is off, causing inductor L and capacitor CFLY to charge simultaneously. In state two, switching device S3 is on, and S1 and S2 are off, causing inductor L and capacitor CFLY to discharge, supplying power to the load. Based on the volt-second balance law of inductor L, the voltage conversion efficiency of this structure can be obtained:

[0081]

[0082] Although this structure does not require a high duty cycle D compared to traditional boost converters 3S While achieving a high conversion ratio and avoiding the surge current of flying capacitors, the improvement in inductor current and switching voltage stress of this structure is not significant, resulting in large inductor parasitic resistance losses and switching conduction losses, and the efficiency still needs to be improved.

[0083] In a specific embodiment, based on the law of capacitance charge balance, analysis of a traditional boost inductor converter reveals that its inductor's DC current... Where D C The duty cycle of a traditional boost converter is given; analysis of the 3S hybrid boost converter proposed by Si-Yi Li reveals the DC current of its inductor. Where D 3s The duty cycle of the 3S structure; the DC current of the inductor in the structure proposed in this invention. Where D represents the duty cycle of the structure of this invention. Under the same voltage conversion ratio M, the inductor current ratios of this invention, a conventional boost inductor converter, and a 3S hybrid boost converter are compared as follows:

[0084]

[0085]

[0086] Among them, K IL，DC K represents the ratio of the DC current of the inductor in the structure proposed in this invention to that in the conventional structure. IL，3S The ratio of the inductor DC current of the structure proposed in this invention to that of the 3S structure is shown in the following graph. Figure 7 As shown in the figure, the formula and graph show that the present invention has a smaller DC current compared with the traditional boost inductor converter and the 3S hybrid boost converter, which can reduce the average inductor current by up to 66.7% and the inductor DC current by up to 50%, respectively.

[0087] Example 3

[0088] Based on the above embodiments 1 and 2, combined with Figures 5-8 This embodiment compares the differences between the present invention and traditional boost inductor converters and 3S hybrid boost converters, and analyzes the inductor current ripple ratio.

[0089] In one specific embodiment, for the same voltage conversion ratio M, the structure proposed in this invention has a small inductance ripple I. L，ac Based on the inductor current law, the inductor ripple current of the traditional boost inductor converter structure and the 3S hybrid boost converter structure are analyzed within one switching cycle. Inductor ripple current in 3S hybrid boost converter structure The inductor ripple current proposed in this invention When the voltage conversion ratio is the same, the ratio of inductor ripple current of the structure proposed in this invention to that of the traditional structure and the 3S structure can be obtained, and the relationship is as follows:

[0090]

[0091]

[0092] Among them, K ΔIL，cbc K ΔIL，3s The figures show the inductor ripple current ratios of the structure of this invention, the traditional boost inductor converter structure, and the 3S hybrid boost converter structure, respectively, and their curves are shown in the figure. Figure 8 As shown in the figure, the structure proposed in this invention has a smaller inductor ripple current, achieving a reduction of up to 33% inductor ripple compared to traditional boost structures and up to 25% inductor ripple compared to 3S structures.

[0093] The icons in the accompanying drawings that depict the structural positional relationships are for illustrative purposes only and should not be construed as limiting this patent.

[0094] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A hybrid boost switching power supply converter, characterized in that, It includes: a first switching device S1, a second switching device S2, a third switching device S3, a fourth switching device S4, a fifth switching device S5, a sixth switching device S6, and a first flying capacitor. Second flying capacitor and inductor L; Input voltage The negative terminal is grounded, and the positive terminal is connected to the drain of the second switching device S2, the drain of the fourth switching device S4, and one end of the inductor L, respectively. The other end of the inductor L is connected to the drain of the first switching device S1 and the first flying capacitor, respectively. One end, the first flying capacitor The other end is connected to the source of the third switching device S3 and the drain of the sixth switching device S6, respectively. The drain of the third switching device S3 is connected to the source of the fourth switching device S4 and the second flying capacitor, respectively. One end, the second flying capacitor The other end is connected to the source of the second switching device S2 and the drain of the fifth switching device S5, respectively, and the source of the sixth switching device S6 outputs voltage. and connected to capacitor One end; where the capacitor The other end, the source of the first switching device S1 and the source of the fifth switching device S5 are both grounded.

2. The hybrid boost switching power converter according to claim 1, characterized in that, According to the first flying capacitor and capacitor The DC current flowing through the inductor L can be obtained using the law of conservation of charge. Its mathematical expression is: Where D represents the duty cycle of the switch control signal; Indicates the first flying capacitor The current; This indicates the load current flowing through the output terminal, where the load is either a load current source or a load resistor.

3. The hybrid boost switching power converter according to claim 1, characterized in that, The maximum voltage stress of the first switching device S1 is -2 The maximum voltage stress of the second switching device S2 is -2 The maximum voltage stress of the third switching device S3 is The maximum voltage stress of the fourth switching device S4 is -2 The maximum voltage stress of the fifth switching device S5 is The maximum voltage stress of the sixth switching device S6 is .

4. A hybrid boost switching power supply converter according to claim 1, characterized in that, First flying capacitor Second Flying Capacitor The capacitance value is 4.7μF.

5. A hybrid boost switching power converter according to claim 1, characterized in that, The inductance value of the inductor L is 4.7 μH.

6. A hybrid boost switching power supply converter according to claim 1, characterized in that, The capacitor This is the load capacitor.

7. A control method for a hybrid boost switching power supply converter, characterized in that, The boost switching power supply converter is a hybrid boost switching power supply converter as described in any one of claims 1-6. The control method is to change the duty cycle of the switching control signal by adjusting the logic control signal of the switching device. When the duty cycle is D, the first switching device S1, the second switching device S2, and the third switching device S3 are controlled to conduct, and the fourth switching device S4, the fifth switching device S5, and the sixth switching device S6 are controlled to cut off. At this time, the second flying capacitor discharges, and the inductor element L and the first flying capacitor charge; where 0 < D < 1, and D represents the duty cycle of the switching control signal.

8. The control method for a hybrid boost switching power supply converter according to claim 7, characterized in that, Based on the duty cycle, the voltage conversion ratio M can be obtained, and its mathematical expression is as follows: ， 0<D<1 in, Indicates the input voltage; This indicates the output voltage.

9. A control method for a hybrid boost switching power supply converter, characterized in that, The boost switching power converter is a hybrid boost switching power converter as described in any one of claims 1-6. By adjusting the logic control signals of the switching devices, the duty cycle of the switching control signals is changed. When the duty cycle is 1-D, the fourth switching device S4, the fifth switching device S5, and the sixth switching device S6 are turned on, while the first switching device S1, the second switching device S2, and the third switching device S3 are turned off. At this time, the inductor L and the first flying capacitor... Discharge to supply power to the load, second flying capacitor Connect to input voltage Charging; of which 0 <D<1 10. The control method for a hybrid boost switching power supply converter according to claim 9, characterized in that, Based on the duty cycle, the voltage conversion ratio M can be obtained, and its mathematical expression is as follows: ， 0<D<1 in, Indicates the input voltage; This indicates the output voltage.

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