A reconfigurable two-stage DCDC power converter and its voltage conversion ratio adjustment method

Abstract

The present invention discloses a reconfigurable DC-DC voltage converter and a method for adjusting its voltage conversion ratio. The voltage converter includes an input source, a first-stage power conversion section, and a second-stage power conversion section. The first-stage power conversion section and the second-stage power conversion section each include a switched capacitor module with N stages, and the conversion ratio can be reconfigured according to demand. The overall conversion ratio of the voltage converter is adjusted by changing the switch control method within the first-stage power conversion section or the second-stage power conversion section. The voltage conversion ratio of the first-stage power conversion section is adjusted based on the load current. When the load current is large, the voltage conversion ratio of the first-stage power conversion section is adjusted; when the load current is small, the voltage conversion ratio of the second-stage power conversion section is adjusted. The present invention can be flexibly expanded according to input and output voltages and output loads, and can reduce switch tube losses and improve efficiency. It is suitable for high-efficiency, wide-voltage conversion ratio DC-DC voltage conversion applications.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to a reconfigurable two-stage DC / DC power converter and a voltage conversion ratio adjustment method thereof. Background Art

[0002] With recent technological advancements, wearable devices and the Internet of Things (IoT) have become increasingly integral to people's lives. Electronic devices powered by switching converters have become increasingly important in society. High-efficiency, wide-ratio DC-DC converters are crucial for portable smart devices powered by batteries or USB.

[0003] Compared to inductive DC-DC converters, switched-capacitor DC-DC converters, which use capacitors as energy storage elements, offer higher power density and smaller size, making them more attractive for low-power or area-constrained applications such as portable electronic devices. Improving the system efficiency of switched-capacitor converter chips to ensure long-term stable operation has become a research hotspot. Existing technologies typically employ a Dickson hybrid topology or a non-reconfigurable two-stage cascade connection to achieve high-efficiency, high-conversion-ratio power supply voltage conversion. While these switched-capacitor converters offer the advantage of a high voltage conversion ratio, this comes at the cost of a reduced output voltage range, typically limiting them to a fixed voltage conversion ratio. When the required input or output voltage varies, the desired output voltage may not be achieved. Conventional two-stage cascade structures or inductive DC-DC converters can achieve a wide output range, but their limitation is that conversion efficiency is significantly affected by load current, making it difficult to guarantee high voltage conversion efficiency across the entire load current range. Summary of the Invention

[0004] In light of the above, to address the existing two-stage structure's inability to balance efficiency and a good input-output voltage range, and to improve the input-output voltage range while maintaining high conversion efficiency, the present invention provides a reconfigurable cascaded DC-DC voltage converter. This voltage converter features a two-stage cascade structure, with the voltage conversion ratio of one stage adjusted based on the load and input-output voltage values. This high conversion efficiency makes it suitable for power supply applications with high conversion ratios and a wide input-output range.

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

[0006] The present invention provides a reconfigurable DCDC voltage converter, which includes: an input source, a first-stage power conversion part, and a second-stage power conversion part, wherein the input source is connected to the input end of the first-stage power conversion part, the output end of the first-stage power conversion part is connected to the input end of the second-stage power conversion part, and the output end of the second-stage power conversion part is connected to a load;

[0007] The first-stage power conversion part and the second-stage power conversion part each include N switching capacitor modules, N-1 transition tubes, a resonant inductor, and an output capacitor;

[0008] The switched capacitor module includes five ports, four switching tubes, and a storage capacitor. The internal connection mode of each switched capacitor module is as follows: the drain of the first switching tube is connected to the first port of the switched capacitor module, the source of the first switching tube, the drain of the second switching tube, the fourth port of the switched capacitor module, and the upper plate of the energy storage capacitor are connected in common, the source of the third switching tube is connected to the second port, the drain of the third switching tube, the lower plate of the energy storage capacitor, the source of the fourth switching tube, and the fifth port of the switched capacitor module are connected in common, and the source of the second switching tube, the source of the fourth switching tube, and the third port of the switched capacitor module are connected in common.

[0009] The internal connection method of the first-stage power conversion part and the second-stage power conversion part is the same, that is, the first port of all switch capacitor modules is connected to the input port in common, the third port of all switch capacitor modules is connected to one end of the resonant inductor, the second port of all switch capacitor modules and the lower plate of the output capacitor are connected to the ground in common, the fifth port of the first switch capacitor module is connected to the drain of the first transition tube, the fourth port of the second switch capacitor module is connected to the source of the first transition tube, the fifth port of the j-th switch capacitor module is connected to the drain of the j-th transition tube, the fourth port of the j+1-th switch capacitor module is connected to the source of the j-th transition tube, and the other end of the resonant inductor, the upper plate of the output capacitor and the output end of the power conversion part are connected in common, where j is an integer and 1≤j≤N-1.

[0010] Furthermore, the energy storage capacitor periodically stores electrical energy and transmits it to the output end of the power conversion part where it is located.

[0011] Furthermore, the transition tube and the switch tube are both switch-type power tubes.

[0012] Furthermore, the switch tube and transition tube used in the first-stage power conversion part are both power semiconductor devices, and the withstand voltage of the power semiconductor devices is higher than the maximum input voltage.

[0013] Furthermore, the switch tube and transition tube used in the second-stage power conversion part are both power semiconductor devices, and the withstand voltage of the power semiconductor devices is higher than the maximum output voltage of the first-stage power conversion part.

[0014] The present invention also provides a method for adjusting the voltage conversion ratio of the above-mentioned voltage converter;

[0015] In a switching cycle, the voltage conversion ratio is adjusted by adjusting the control signals of the internal switching power transistors of the first-stage power conversion part and the second-stage power conversion part according to the output load current of the voltage converter;

[0016] The intermediate current between the output end of the first-stage power conversion part and the input end of the second-stage power conversion part is selected as the judgment basis. When the load current is greater than the intermediate current, the switch control signal inside the first-stage power conversion part is adjusted to adjust the voltage conversion ratio.

[0017] When the load current is less than the intermediate current, the voltage conversion ratio is adjusted by adjusting the switch control signal inside the second-stage power conversion part.

[0018] The technology of this invention adjusts the conversion ratio of the voltage converter by changing the control method of the switching tubes within the first-stage power conversion part or the second-stage power conversion part. Based on the load current, the intermediate current between the output end of the first power conversion part and the second power conversion part is used as the judgment standard. When the load current is high, the voltage conversion ratio of the first-stage power conversion part is adjusted; when the load current is low, the voltage conversion ratio of the second-stage power conversion part is adjusted. This achieves a wide voltage conversion ratio, reduces losses, and improves efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a system connection diagram of a reconfigurable two-stage voltage converter according to a first embodiment of the present invention;

[0020] Figure 2 A circuit topology diagram of a power conversion portion of a two-stage voltage converter according to a first embodiment of the present invention for achieving a first voltage conversion ratio;

[0021] Figure 3 This is a working waveform diagram of the first voltage conversion ratio achieved in the first embodiment of the present invention;

[0022] Figure 4 A circuit topology diagram for realizing a second voltage conversion ratio in the power conversion portion of the two-stage voltage converter of the first embodiment of the present invention;

[0023] Figure 5 This is a working waveform diagram of the first embodiment of the present invention for achieving the second voltage conversion ratio;

[0024] Figure 6 A circuit topology diagram for realizing a third voltage conversion ratio in the power conversion portion of the two-stage voltage converter of the first embodiment of the present invention;

[0025] Figure 7 This is a working waveform diagram of the first embodiment of the present invention for achieving the third voltage conversion ratio;

[0026] Figure 8 This is a system circuit diagram of a reconfigurable two-stage DC-DC voltage converter according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] To more clearly demonstrate the above-mentioned features and advantages of the present invention, the present invention will be described below based on embodiments, but the present invention is not limited to these embodiments. In the detailed description of the present invention below, certain specific details are described in detail. Those skilled in the art can fully understand the present invention without the description of these details. To avoid obscuring the essence of the present invention, well-known methods, processes, procedures, components, and circuits are not described in detail. The technical features of the various embodiments of the present invention can be combined accordingly without conflicting requirements.

[0028] Unless the context clearly requires otherwise, throughout the specification and claims, the words "include," "comprising," and similar words should be construed in an inclusive sense rather than an exclusive or exhaustive sense; that is, in the sense of "including but not limited to."

[0029] In the description of the present invention, it should be understood that the terms "first", "second", etc. are used for descriptive purposes only and should not be understood to indicate or imply relative importance. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0030] Figure 1 This is a connection diagram of a reconfigurable two-stage DC-DC voltage converter according to one embodiment of the present invention. The converter includes an input source, a first-stage power conversion section, and a second-stage power conversion section. The input source is connected to the first-stage power conversion section, and the load is connected to the second-stage power conversion section.

[0031] Figure 2 This is a schematic diagram of the internal circuit topology of the first-stage and second-stage power conversion sections based on switched capacitors according to an embodiment of the present invention. The components include two switched capacitor modules, a transition transistor Q5, an inductor, and an output capacitor. The first switched capacitor module includes switches Q1, Q2, Q3, Q4, and a storage capacitor C1, while the second switched capacitor module includes switches Q6, Q7, Q8, Q9, and a storage capacitor C2. Switches Q1, Q4, Q6, and Q9 are controlled by signal G1, while switches Q2, Q3, Q7, and Q8 are controlled by signal G2. The transition transistor Q5 is always off, achieving a 2:1 input-to-output voltage conversion ratio.

[0032] Figure 3 This is a working waveform diagram of the power conversion part of an embodiment of the present invention to achieve the first voltage conversion ratio. Figure 3 As shown in the figure, when control signal G1 is high, switches Q1, Q4, Q6, and Q9 are turned on, switches Q2, Q3, Q7, and Q8 are turned off, and transition transistor Q5 is turned off. At this time, the input voltage VIN charges energy storage capacitors C1 and C2, and the voltage across C1 and C2 increases. After the dead time Td, when control signal G2 is high, switches Q2, Q3, Q7, and Q8 are turned on, switches Q1, Q4, Q6, and Q9 are turned off, and transition transistor Q5 is turned off. At this time, energy storage capacitors C1 and C2 discharge, and the voltage across C1 and C2 decreases. The high level time of control signals G1 and G2 is both half of the cycle. The voltage across energy storage capacitors C1 and C2 is approximately half of VIN, and the voltage VOUT obtained at the output terminal is half of the input voltage VIN.

[0033] Figure 4 This is a schematic diagram of a circuit topology implementing another voltage conversion ratio according to an embodiment of the present invention. Switches Q1, Q4, Q6, and Q9 are controlled by signal G1, while switches Q2, Q8, and transition transistor Q5 are controlled by signal G2. Switches Q3 and Q7 are always off, achieving an input-to-output voltage conversion ratio of 3:2.

[0034] Figure 5 This is a working waveform diagram of the power conversion part of an embodiment of the present invention to achieve the second voltage conversion ratio. Figure 5 As shown, when control signal G1 is high, switches Q1, Q4, Q6, and Q9 are turned on, switches Q2, Q3, Q7, and Q8 are turned off, and transition transistor Q5 is turned off. At this time, input voltage VIN charges energy storage elements C1 and C2, causing the voltage across C1 and C2 to rise. After dead time Td, when control signal G2 is high, switches Q2 and Q8 are turned on, transition transistor Q5 is turned on, and switches Q1, Q3, Q4, Q6, Q7, and Q9 are turned off. At this time, energy storage capacitors C1 and C2 discharge, causing the voltage across C1 and C2 to drop. The high-level duration of control signal G1 is two-thirds of period Ts, and the high-level duration of control signal G2 is one-third of period Ts. The voltage across energy storage capacitors C1 and C2 is approximately one-third of VIN.

[0035] Figure 6 This is a schematic diagram of a circuit topology implementing the third voltage conversion ratio according to an embodiment of the present invention. Switches Q1, Q9, and transition transistor Q5 are controlled by signal G1, while switches Q2, Q3, Q7, and Q8 are controlled by signal G2. Switches Q4 and Q6 are always off, achieving an input-to-output voltage conversion ratio of 3:1.

[0036] Figure 7This is a working waveform diagram of the power conversion part of an embodiment of the present invention to achieve the third voltage conversion ratio. Figure 7 As shown, when control signal G1 is high, switches Q1 and Q9 are turned on, transition transistor Q5 is turned on, and switches Q2, Q3, Q7, Q8, Q4, and Q6 are turned off. At this time, input voltage VIN charges energy storage capacitors C1 and C2, causing the voltage across C1 and C2 to rise. After dead time Td, when control signal G2 is high, switches Q2, Q3, Q7, and Q8 are turned on, switches Q1, Q9, Q4, and Q6 are turned off, and transition transistor Q5 is turned off. At this time, energy storage capacitors C1 and C2 discharge, causing the voltage across C1 and C2 to drop. The high-level duration of control signal G1 is one-third of period Ts, and the high-level duration of control signal G2 is two-thirds of period Ts. The voltage across energy storage capacitors C1 and C2 is both approximately one-third of VIN.

[0037] Figure 8 This diagram shows the system circuit topology of a reconfigurable two-stage DC-DC voltage converter according to an embodiment of the present invention. The converter includes an input source, a first-stage power conversion section, a second-stage power conversion section, and an output load. The circuit topology and operating waveforms show that both the first-stage and second-stage power conversion sections can achieve voltage conversion ratios of 1 / 2, 1 / 3, and 2 / 3.

[0038] The advantages of the present invention will be explained below through theoretical analysis in conjunction with specific embodiments. Figure 8 Taking the embodiment as an example, the first-stage power conversion part is connected to the input source and requires a higher withstand voltage, but as an intermediate stage, the output current is relatively small; the second power conversion part is connected to the output load, and the current flowing through the switch tube is equal to the load current. In steady-state operation, the voltage conversion ratios of the first-stage power conversion part and the second-stage power conversion part are both 2 / 3, and the total voltage conversion ratio is the multiplication of the voltage conversion ratios of the first and second stages, which is 4 / 9. When the input voltage increases or the output voltage decreases, the voltage conversion ratio of the DCDC voltage converter needs to be increased. For the internal circuit topology of the power conversion part, when the voltage conversion ratio changes from 2 / 3 to 1 / 2 or 1 / 3, the conversion ratio increases, which may increase the transistor loss during conduction, increase the internal circuit loss, and cause the voltage conversion efficiency to decrease. The loss depends on the load current.

[0039] At this time, it is necessary to adjust the voltage conversion ratio of the first or second stage power conversion part according to the load conditions to obtain a suitable input-output ratio: the intermediate current between the output end of the first stage power conversion part and the input end of the second stage power conversion part is selected as the judgment basis. When the load current is greater than the intermediate current, since the current in the second stage power conversion part is equal to the load current, increasing the voltage conversion ratio of the second stage will increase more losses and reduce the conversion efficiency. Therefore, the first stage power conversion part is selected to be reconstructed, and the voltage conversion ratio of the first stage power conversion part is increased to improve the overall voltage conversion ratio and obtain a higher voltage conversion efficiency; when the load current is less than the intermediate current, the second stage power conversion part is reconstructed to obtain the required voltage conversion ratio. In traditional solutions, the usual two-stage structure can only provide a fixed voltage conversion ratio, or only one stage can be reconstructed. Therefore, the present invention can be suitable for applications with a wide input and output voltage range while taking into account a higher voltage conversion efficiency.

[0040] from Figure 8 It can be seen from the specific embodiment shown that the circuits and switched capacitor modules in the first-stage and second-stage conversion power parts are exactly the same. Therefore, it is only necessary to design the parameters of a single module to complete the design of the entire power part. Moreover, for different input voltage levels, it is only necessary to adjust the number of modules without redesigning the module parameters.

[0041] The above examples specifically illustrate and describe exemplary implementations of the present invention. The above embodiments are only used to illustrate the technical solutions of the present invention so that those skilled in the art can understand and apply the present invention. The present invention is not limited to the detailed structures, configuration methods, or implementations described herein. It should be noted that it is obvious that those skilled in the art can easily make various modifications to the above embodiments, or replace some or all of the technical features of the present invention with equivalents, or apply the general principles described herein to other embodiments without creative work. Modifications, improvements, or equivalent replacements of technical features of the present invention should all fall within the scope of protection of the present invention.

Claims

1. A reconfigurable DCDC voltage converter, characterized in that include: An input source, a first-stage power conversion part, and a second-stage power conversion part, wherein the input source is connected to an input end of the first-stage power conversion part, an output end of the first-stage power conversion part is connected to an input end of the second-stage power conversion part, and an output end of the second-stage power conversion part is connected to a load; The first-stage power conversion part and the second-stage power conversion part each include N switching capacitor modules, N-1 transition tubes, a resonant inductor, and an output capacitor; The switched capacitor module includes five ports, four switching tubes, and a storage capacitor. The internal connection mode of each switched capacitor module is as follows: the drain of the first switching tube is connected to the first port of the switched capacitor module, the source of the first switching tube, the drain of the second switching tube, the fourth port of the switched capacitor module, and the upper plate of the energy storage capacitor are connected in common, the drain of the third switching tube is connected to the second port, the source of the third switching tube, the lower plate of the energy storage capacitor, the drain of the fourth switching tube, and the fifth port of the switched capacitor module are connected in common, and the source of the second switching tube, the source of the fourth switching tube, and the third port of the switched capacitor module are connected in common. The internal connection method of the first-stage power conversion part and the second-stage power conversion part is the same, that is, the first port of all switch capacitor modules is connected to the input port in common, the third port of all switch capacitor modules is connected to one end of the resonant inductor, the second port of all switch capacitor modules and the lower plate of the output capacitor are connected to the ground in common, the fifth port of the first switch capacitor module is connected to the drain of the first transition tube, the fourth port of the second switch capacitor module is connected to the source of the first transition tube, the fifth port of the j-th switch capacitor module is connected to the drain of the j-th transition tube, the fourth port of the j+1-th switch capacitor module is connected to the source of the j-th transition tube, and the other end of the resonant inductor, the upper plate of the output capacitor and the output end of the power conversion part are connected in common, where j is an integer and 1≤j≤N-1.

2. The reconfigurable DCDC voltage converter according to claim 1, wherein: The energy storage capacitor periodically stores electric energy and transmits it to the output end of the power conversion part where it is located.

3. The reconfigurable DCDC voltage converter according to claim 1, wherein: The transition tube and the switch tube are both switch-type power tubes.

4. The reconfigurable DCDC voltage converter according to claim 1, wherein: The switch tube and transition tube used in the first-stage power conversion part are both power semiconductor devices, and the withstand voltage of the power semiconductor devices is higher than the maximum input voltage.

5. The reconfigurable DCDC voltage converter according to claim 1, wherein: The switch tube and transition tube used in the second-stage power conversion part are both power semiconductor devices, and the withstand voltage of the power semiconductor devices is higher than the maximum output voltage of the first-stage power conversion part.

6. A method for adjusting the voltage conversion ratio of a voltage converter according to any one of claims 1 to 5, characterized in that ； In a switching cycle, the voltage conversion ratio is adjusted by adjusting the control signals of the internal switching power transistors of the first-stage power conversion part and the second-stage power conversion part according to the output load current of the voltage converter; The intermediate current between the output end of the first-stage power conversion part and the input end of the second-stage power conversion part is selected as the judgment basis. When the load current is greater than the intermediate current, the switch control signal inside the first-stage power conversion part is adjusted to adjust the voltage conversion ratio. When the load current is less than the intermediate current, the voltage conversion ratio is adjusted by adjusting the switch control signal inside the second-stage power conversion part.

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