Voltage-adjustable resonant DC-DC converter

Abstract

The invention provides a wide-input-range voltage-adjustable resonant DC-DC converter, and the converter comprises a voltage adjusting stage which is connected with an input end, and is configured to work at a first frequency, and carries out the magnetizing and demagnetizing control of a power inductor in the voltage adjusting stage; the resonant switched capacitor topology circuit is connected to the tail end of the inductor in the voltage regulating stage, a high-low level switching node is formed at the joint, the switched capacitor topology circuit comprises a plurality of resonant tank units, and the plurality of resonant tank units work at a second resonant frequency; therefore, the voltage at the high-low level switching node is switched between the high-power value and the low-power value of the specific output voltage, and the soft switching of the switched capacitor topology circuit is realized.

Description

Technical Field

[0001] The present disclosure relates to the technical field of circuit design, and in particular to a wide input range adjustable voltage resonant DC-DC converter. Background Art

[0002] As a resonant switched capacitor DC-DC converter, the Switched Tank Converter (STC) is mainly used in the next generation of high bus voltage (48V) servers and other high power applications. It completes voltage conversion based on the resonant working mode of inductance and capacitance, and can achieve high efficiency and high power density under fixed conversion ratio conditions (mainly 4:1 conversion ratio), thereby generating an intermediate bus voltage of 12V. In the server, multiple modules and subsystems require a stable lower voltage power supply (such as 5V or 3.3V) to ensure their normal operation, such as I / O interfaces, memory modules, air cooling systems, etc. Therefore, it is often necessary to add an additional adjustable voltage step-down DC-DC converter (Buck) to further reduce the voltage and realize 12V to 3.3V-5V conversion.

[0003] However, this two-stage architecture of STC+ Buck has two main problems. First, as a resonant switched capacitor DC-DC converter, STC needs to work at a specific resonant frequency to achieve soft switching of power devices to achieve high efficiency. Therefore, the converter relies on resonant capacitors or inductors with stable parameter values. Since the DC voltage of the resonant capacitor is related to the input voltage, Class I ceramic capacitors have the advantages of high stability, high precision, and voltage insensitivity compared to Class II. They are suitable for resonant switched capacitor DC-DC converters to achieve stable capacity under a wide input voltage range. However, they have the disadvantages of low capacity density and high price. They often require multiple capacitors to be connected in parallel, resulting in increased costs and reduced power density. Class II ceramic capacitors have serious capacitance attenuation with DC bias when used, resulting in the shift of resonant frequency with input voltage. Secondly, the power inductor used for voltage regulation in the two-stage architecture is located at the output end and needs to withstand a DC current equal to the load current. Therefore, the direct current resistance (DCR) conduction loss of the inductor is high, and the system efficiency is limited. Summary of the invention

[0004] In view of this, in order to at least partially solve at least one of the above-mentioned technical problems, the present disclosure provides a wide input range adjustable voltage resonant DC-DC converter.

[0005] In order to achieve the above purpose, the technical solution of the present invention is as follows:

[0006] According to an embodiment of the present disclosure, there is provided an adjustable voltage resonant DC-DC converter, comprising: a voltage regulating stage, connected to an input end and configured to operate at a first frequency to perform charging and demagnetization control on a power inductor in the voltage regulating stage; a resonant switched capacitor topology circuit, connected to the end of the inductor in the voltage regulating stage and forming a high-low level switching node at the connection, the switched capacitor topology circuit comprising a plurality of resonant slot units, the plurality of resonant slot units operating at a resonant second frequency, so that the voltage at the high-low level switching node switches between a high multiple value and a low multiple value of a specific output voltage, thereby realizing soft switching of the switched capacitor topology circuit.

[0007] According to an embodiment of the present disclosure, the frequency value of the second frequency is higher than the frequency value of the first frequency.

[0008] According to an embodiment of the present disclosure, the voltage regulating stage includes a high-side tube S H , low side tube S L , power inductor L, among which, high-side tube S H One end is connected to the input end, and the other end is connected to the first end a of the power inductor L. The high-side tube S H A node SW0 is set between the power inductor L and the low-side tube S L The node SW0 is connected to ground.

[0009] According to an embodiment of the present disclosure, each resonant tank unit includes a flying capacitor, a power switch, and a resonant tank. The voltage at the high-low level switching node is switched between a high multiple value and a low multiple value of a specific output voltage by connecting and disconnecting different power switches in a linked manner.

[0010] According to an embodiment of the present disclosure, a voltage-adjustable resonant DC-DC converter includes two resonant tank units, namely a first resonant tank unit and a second resonant tank unit.

[0011] According to an embodiment of the present disclosure, the first resonant tank unit includes a power switch S 1 , power switch S 2 , power switch S 3 , power switch S 4 , power switch S 5 , power switch S 6 , flying capacitor C F1 , resonant inductor L R1 , resonant capacitor C R1 , resonant inductor L R1 and resonant capacitor C R1 The first resonant tank is formed; wherein the power switch S 1 One end is connected to the second end b of the power inductor L in the voltage regulation stage through the high-low level switching node SW1, and the power switch S 1 The other end is connected to the power switch S via node SW3.2 , the high and low level switching node SW1 connects the flying capacitor C F1 After passing through node SW2 and power switch S 6 Then the node SW3 is connected to the resonant capacitor C R1 , resonant inductor L R1 After passing through node SW4 and power switch S 4 The other side of node SW4 is connected to the power switch S 3 and power switch S 5 Then connected to node SW2, the power switch S 2 Then connect the power switch S 5 And connected to node SW2.

[0012] According to an embodiment of the present disclosure, the second resonant tank unit includes a power switch S 7 , power switch S 8 , power switch S 9 , power switch S 10 , power switch S 11 , power switch S 12 , flying capacitor C F2 , resonant inductor L R2 , resonant capacitor C R2 , resonant inductor L R2 and resonant capacitor C R2 The second resonant tank is formed; wherein the power switch S 7 One end is connected to the first resonant tank unit via node SW5, and the power switch S 7 The other end is connected to the power switch S8 via the node SW7, and the node SW5 is connected to the flying capacitor C F2 Then it is connected to the ground through the node SW6 and the power switch S12, and the node SW7 is connected to the resonant capacitor C R2 , resonant inductor L R2 Then it passes through node SW8 and power switch S10 and is grounded. The other side of node SW8 is connected to power switch S 9 and power switch S 11 Then connected to node SW2, the power switch S 8 Then connect the power switch S 11 And connected to node SW6.

[0013] According to an embodiment of the present disclosure, the resonant switched capacitor topology circuit operates at a second frequency and a 50% duty cycle; in a half cycle, the power switch S 1 , S 3 , S 6 , S 7 , S 9 , S 12 Disconnect, power switch S 2 , S4 , S 5 , S 8 , S 10 , S 11 conduction, power inductor L to flying capacitor C F1 Charging, the first resonant tank discharges, the flying capacitor C F2 At the same time, the resonant capacitor C F1 The two paths of the first resonant tank are charged, and at the same time, the second resonant tank is also discharged; the flying capacitor C F2 The second resonant tank is connected in parallel to charge the load; the DC voltage of each flying capacitor can be calculated according to Kirchhoff's voltage law: V CF1 =5V O , V CF2 =2V O ; The voltage at the high-low level switching node SW1 rises to a high voltage V H , V H =V CF1 + V CF2 + V O =8V O , where V CF1 Represents the flying capacitor C F1 Voltage, V CF2 Represents the flying capacitor C F2 Voltage, V O Indicates the load voltage. In the other half cycle, the power switch S 1 , S 3 , S 6 , S 7 , S 9 , S 12 Turn on, power switch S 2 , S 4 , S 5 , S 8 , S 10 , S 11 Disconnect, power inductor L and flying capacitor C F1 The first resonant tank is charged in parallel, while the second resonant tank is connected in series with the load and connected by the first resonant tank and the flying capacitor C F2 Connect it in parallel to charge it, the flying capacitor C F1 And the flying capacitor C F2 Discharge, the voltage at the high-low level switching node SW1 drops to a low voltage V L , V L =V CF1 =5V O .

[0014] According to an embodiment of the present disclosure, the second resonant frequency values ​​of the plurality of resonant tank units only depend on the parameter values ​​of the resonant inductance and the resonant capacitance within the resonant tank units. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0016] Figure 1 The invention is a switch slot converter with a two-stage structure in the prior art.

[0017] Figure 2 The invention is a switch slot converter with a two-stage structure optimized in the prior art.

[0018] Figure 3 It is a schematic diagram of the principle structure of a two-stage switch slot converter in the prior art.

[0019] Figure 4 Schematic diagram of a circuit of an adjustable voltage resonant DC-DC converter according to an embodiment of the present disclosure.

[0020] Figure 5 Schematic diagram of different working states of the adjustable voltage resonant DC-DC converter according to an embodiment of the present disclosure.

[0021] Figure 6 Schematic diagram of key waveforms of the adjustable voltage resonant DC-DC converter under different working states according to an embodiment of the present disclosure.

[0022] Figure 7 The schematic diagram is a working principle framework of an adjustable voltage resonant DC-DC converter according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0023] The present disclosure provides a wide input range adjustable voltage resonant DC-DC converter, whose resonant topology is only related to the output voltage and has nothing to do with the input voltage, and reduces the DC voltage difference of the resonant capacitor between the two resonant tanks, avoiding the large attenuation range of the resonant capacitor under a wide input voltage range and the attenuation mismatch caused by the resonant tank voltage difference. Therefore, only low-cost, high-capacitance density Class II ceramic capacitors are needed to achieve the insensitivity of the resonant frequency to the wide input voltage, saving complex frequency calibration or zero-current switch control circuits, reducing costs and improving power density. In addition, the inductor current in this architecture is reduced to 1 / 6.5 of the output current, which fully reduces the DCR conduction loss, improves the conversion efficiency, and improves the utilization rate of passive devices, further improving the voltage conversion ratio.

[0024] Unlike switched capacitor converters, the STC in the existing technology uses LC resonant tanks to partially replace flying capacitors for energy transfer, which can achieve full soft charging, soft switching and minimum device voltage stress under all operating conditions, thereby achieving high efficiency and high power density, and is a good replacement for transformer-based converter architectures. In addition, due to full resonant operation, multiple STCs can operate in parallel, providing optimal scalability and control simplicity. These features make STC a disruptive and powerful technology that has been widely used in its next-generation 48V two-stage power supply architecture, such as Figure 1 As shown, the STC acts as a front stage with a fixed conversion ratio of 4:1 to output 12V, and a rear stage uses an adjustable voltage Buck to further step down the voltage to 3.3V-5V to power the server module and subsystem.

[0025] In order to improve the conversion efficiency of the above converter architecture, a research team has optimized it by reusing power switches [reference paper: SY Sim, X. Zhang, J. Jiang, K. Wei, and C. Huang, “A 94.7%Efficiency Direct-Step-Down Switched-Tank-Based 48V to 1V-3.3V HybridConverter with Constant-Resonant-Time Closed-Loop Control,” in 2024 IEEEApplied Power Electronics Conference and Exposition (APEC), Long Beach, CA, USA, Feb. 2024, pp. 1344–1350.], such as Figure 2 As shown, by reducing the number of power switches required, efficiency is improved.

[0026] The above two solutions can be equivalent to Figure 3Traditional two-stage architecture block diagram of the upper part. For the input voltage of the 48V bus, considering factors such as different operating states of the uninterruptible power supply (UPS) in the rack, load fluctuations, and ambient temperature, the 48V bus often has a relatively wide input voltage range: 36V - 60V. Therefore, the first-stage STC performs a conversion with a fixed voltage ratio of 4:1 to generate an intermediate-stage voltage of 9V - 15V. Considering the selection of resonant capacitors, among the commercially available surface-mount ceramic capacitors on the market currently, Class I ceramic capacitors (materials include C0G, U2J, etc.) have characteristics such as high stability, high precision, voltage insensitivity, low dielectric constant, low capacitance density, and high price, and are usually applied to occasions such as resonant circuits, high-frequency circuits, and temperature compensation circuits; while Class II ceramic capacitors (materials include X7R, X7S, etc.) have characteristics such as high dielectric constant, high capacitance density, low cost, and voltage sensitivity, and are usually applied to power supply bypass or decoupling applications. For a resonant switched-capacitor DC-DC converter, it generally needs to operate at a specific resonant frequency to achieve soft switching of power devices to achieve high efficiency. Therefore, this converter is more dependent on capacitors with stable capacitance and insensitivity to bias voltage. Considering that in a wide input voltage range, the bias voltage difference of the resonant capacitors in the two LC resonant tanks of the STC is large and the variation range is wide. If Class II ceramic capacitors are used (for example, taking the use of Murata GRM31CR72A105KA01 as an example), as Figure 3 shown, the variation of a single resonant capacitor with the input voltage can be as high as 22%, and the capacitance difference between the two resonant capacitors can also be as high as 37%, which will lead to the variation of the resonant frequency with the input voltage and the mismatch of the resonant frequencies of the two resonant tanks respectively, so that a complex frequency calibration or zero-current switching control circuit needs to be introduced to calibrate the operating frequency to maintain high efficiency. Therefore, Class I ceramic capacitors are selected for the above two operations for the resonant capacitors. However, its lower capacitance density means that the number of parallel connections needs to be increased to achieve a specific capacitance value, which further increases the cost and deteriorates the power density.

[0027] Another problem is that in the subsequent Buck converter of the traditional two-stage architecture, since the power inductor for voltage regulation is located at the output end and needs to bear a direct current amount equal to the load current, the DCR conduction loss of the inductor is high, which deteriorates the system efficiency. Therefore, in order to achieve high efficiency, it is often necessary to select large-size power inductors with small DCR and large saturation current, which is not conducive to the miniaturization of the system and the improvement of power density. In addition, the overall conversion ratio of the traditional architecture is D / 4, where D represents the duty cycle of the power switch control signal in the subsequent Buck (0 < D < 1), the utilization rate of passive devices is insufficient, the equivalent conduction time extension is limited, and it is difficult to achieve an output with a larger conversion ratio.

[0028] It can be seen that the DC voltage of the resonant capacitor in the traditional STC+ Buck two-stage architecture is related to the input voltage. For wide input voltage application scenarios, this architecture strongly relies on constant-capacity Class I ceramic capacitors as resonant capacitors to obtain a constant resonant frequency to achieve high efficiency, so the cost is high and the power density is low. In addition, the DC current of the voltage-regulated power inductor is equal to the load current, the DCR conduction loss of the inductor is high, the system conversion efficiency is low, and the passive device utilization is insufficient, making it difficult to achieve a higher conversion ratio output.

[0029] Based on the above shortcomings, the present invention provides a wide input voltage range adjustable resonant DC-DC converter, whose resonant capacitor voltage is only related to a specific output voltage and reduces the DC voltage difference of the resonant capacitor between the two resonant slots, avoiding the large attenuation range of the resonant capacitor under a wide input voltage range and the attenuation mismatch caused by the resonant slot voltage difference. Therefore, only low-cost, high-capacitance density Class II ceramic capacitors are needed to achieve the insensitivity of the resonant frequency to the wide input voltage, saving complex frequency calibration or zero current switch control circuits, reducing costs and improving power density. In addition, the inductor current in this architecture is reduced to 1 / 6.5 of the output current, which fully reduces the DCR conduction loss, improves the conversion efficiency, and relaxes the requirements for large size, small DCR, and high saturation current inductors; and improves the utilization rate of passive devices, and the voltage conversion ratio is reduced from D / 4 of the traditional architecture to D / 6.5, which is more conducive to the output of a large conversion ratio and extends the equivalent conduction time.

[0030] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0031] In an embodiment of the present disclosure, a voltage-adjustable resonant DC-DC converter is provided. Figure 4 As shown, it includes: a voltage regulation stage and a resonant switched capacitor topology circuit.

[0032] The voltage regulating stage is connected to the input terminal and is configured to operate at a first frequency to perform charging and demagnetization control on the power inductor in the voltage regulating stage;

[0033] The resonant switched capacitor topology circuit is connected to the end of the inductor in the voltage regulating stage and forms a high-low level switching node at the connection. The switched capacitor topology circuit includes a plurality of resonant tank units, and the plurality of resonant tank units operate at a second frequency of resonance, so that the voltage at the high-low level switching node switches between a high multiple value and a low multiple value of a specific output voltage, thereby realizing soft switching of the switched capacitor topology circuit.

[0034] The basic structure of the voltage regulator stage is similar to that of a Buck converter, which consists of a high-voltage power switch and a power inductor. Hand low side S L ) to handle a wide input voltage range (e.g. 6V-60V), and is modulated by duty cycle D to regulate the global output voltage; the resonant switched capacitor topology circuit structure is composed of a low-voltage power switch, a flying capacitor, a resonant inductor, and a resonant capacitor. Unlike the two-stage architecture, the node SW1 at the connection between the voltage regulation stage and the resonant switched capacitor topology circuit is not an intermediate DC voltage, but a switch node that switches between two high and low levels. Therefore, the power supply architecture of the present invention is actually equivalent to a single-stage converter, which saves the DC decoupling capacitor C required for the intermediate voltage compared to the traditional two-stage architecture converter. mid There are many possible implementations of the switches in the present invention, and there are many implementations, for example, including but not limited to various voltage-resistant NMOS, PMOS, and some switches can even use diodes.

[0035] According to the embodiment of the present disclosure, Figure 4 and Figure 5 As shown, the voltage regulating stage includes a high-side tube S H , low side tube S L , power inductor L, among which, high-side tube S H One end is connected to the input end, and the other end is connected to the first end a of the power inductor L. The high-side tube S H A node SW0 is set between the power inductor L and the low-side tube S L Each resonant tank unit includes a flying capacitor, a power switch, and a resonant tank, and the voltage at the high-low level switching node is switched between a high multiple value and a low multiple value of a specific output voltage by connecting and disconnecting different power switches.

[0036] According to an embodiment of the present disclosure, the frequency value of the second frequency is higher than the frequency value of the first frequency. Figure 4 and Figure 5 , Figure 7 As shown, the voltage regulator stage works at T SW The switching cycle of the high-side tube S H With low side tube S L Under the control of a pulse width modulation signal (PWM), the duty cycle D modulates the charging and demagnetization states of the power inductor L to adjust the terminal output voltage, and the PWM signal is generated by feedback from a control circuit (not shown in the figure). The control circuit can refer to the design of the control stage in a traditional DC-DC converter, which will not be described in detail here.

[0037] Combination Figure 4 and Figure 5 , Figure 7 As shown, the adjustable voltage resonant DC-DC converter includes two resonant tank units, namely a first resonant tank unit and a second resonant tank unit. The first resonant tank unit includes a power switch S 1, power switch S 2 , power switch S 3 , power switch S 4 , power switch S 5 , power switch S 6 , flying capacitor C F1 , resonant inductor L R1 , resonant capacitor C R1 , resonant inductor L R1 and resonant capacitor C R1 The first resonant tank is formed; wherein the power switch S 1 One end is connected to the second end b of the power inductor L in the voltage regulation stage through the high-low level switching node SW1, and the power switch S 1 The other end is connected to the power switch S via node SW3. 2 , the high-low level switching node SW1 connects the flying capacitor C F1 After passing through node SW2 and power switch S 6 Then the node SW3 is connected to the resonant capacitor C R1 , resonant inductor L R1 After passing through node SW4 and power switch S 4 The other side of node SW4 is connected to the power switch S 3 and power switch S 5 Then connected to node SW2, the power switch S 2 Then connect the power switch S 5 And connected to node SW2.

[0038] The second resonant tank unit includes a power switch S 7 , power switch S 8 , power switch S 9 , power switch S 10 , power switch S 11 , power switch S 12 , flying capacitor C F2 , resonant inductor L R2 , resonant capacitor C R2 , resonant inductor L R2 and resonant capacitor C R2 The second resonant tank is formed; wherein the power switch S 7 One end is connected to the first resonant tank unit via node SW5, and the power switch S 7 The other end is connected to the power switch S8 via the node SW7, and the node SW5 is connected to the flying capacitor C F2 Then it is connected to the ground through the node SW6 and the power switch S12, and the node SW7 is connected to the resonant capacitor C R2 , resonant inductor L R2 Then it passes through node SW8 and power switch S10 and is grounded. The other side of node SW8 is connected to power switch S9 and power switch S 11 Then connected to node SW2, the power switch S 8 Then connect the power switch S 11 And connected to node SW6.

[0039] According to the embodiment of the present disclosure, the switched capacitor topology circuit operates at T R The switching cycle is set to operate at a second frequency and a 50% duty cycle.

[0040] In a half cycle (Φ R1 ), the power switch S 1 , S 3 , S 6 , S 7 , S 9 , S 12 Disconnect, power switch S 2 , S 4 , S 5 , S 8 , S 10 , S 11 conduction, power inductor L to flying capacitor C F1 Charging, the first resonant tank discharges, the flying capacitor C F2 At the same time, the resonant capacitor C F1 The two paths of the first resonant tank are charged, and at the same time the second resonant tank is also discharged; the flying capacitor C F2 The second resonant tank is connected in parallel to charge the load; according to Kirchhoff's voltage law, the DC voltage of each flying capacitor can be calculated: V CF1 =5V O , V CF2 =2V O ; The voltage at the high-low level switching node SW1 rises to a high voltage V H , V H =V CF1 + V CF2 + V O =8V O , where V CF1 Represents the flying capacitor C F1 Voltage, V CF2 Represents the flying capacitor C F2 Voltage, V O Indicates the load voltage. In the other half cycle (Φ R2 ), power switch S 1 , S 3 , S 6 , S 7 , S 9 , S 12 Turn on, power switch S 2 , S 4, S 5 , S 8 , S 10 , S 11 Disconnect, power inductor L and flying capacitor C F1 The first resonant tank is charged in parallel, while the second resonant tank is connected in series with the load and connected by the first resonant tank and the flying capacitor C F2 Connect it in parallel to charge it, the flying capacitor C F1 And the flying capacitor C F2 Discharge, the voltage at the high-low level switching node SW1 drops to a low voltage V L , V L =V CF1 =5V O .

[0041] Therefore, the high-low level switching node SW1 is at a high level of 8V O With low level 5V O The resonant network is equivalent to a voltage conversion ratio of 6.5:1, and the DC current of the power inductor is reduced to 1 / 6.5 of the load current, which effectively reduces the inductor DCR conduction loss and is conducive to improving efficiency.

[0042] Compared with the traditional two-level architecture, this architecture will save C mid Capacitor as flying capacitor C F1 Two power switches are introduced on the lower plate to control the charge and discharge state to increase the amount of charge transferred. The charge of the first resonant tank is determined by the power inductor L and the flying capacitor C. F1 The charge of the second resonant tank is obtained by accumulating the charge of the first resonant tank and the flying capacitor C F2 It is accumulated that the sub-circuit resonant switched capacitor topology circuit proposed in the present invention has the function of charge transfer amplification. Compared with the STC in the traditional architecture, the utilization rate of the capacitor components is improved without adding additional passive components, and the voltage conversion ratio is further improved from 4:1 to 6.5:1, thereby effectively extending the equivalent on-time of the voltage regulation stage and avoiding the design challenges brought by too narrow duty cycle to the control and drive circuits.

[0043] Due to the voltage domain separation effect of the power inductor L, the voltage regulator stage and the resonant switched capacitor topology circuit can operate at different frequencies (first frequency and second frequency) to achieve the best working state. For example, since the voltage regulator stage uses high-voltage power devices, in order to reduce its switching loss, it can be set to operate at a lower first frequency (period is T SW ); The resonant switched capacitor topology circuit must operate at a higher and resonant second frequency to ensure soft switching of each power device (period is T R ), the resonant frequency can be calculated based on the selected resonant inductor and capacitor parameters. Figure 5 As shown in the figure, the two working sequences can obtain equivalent circuits of two states, where the power inductor has a large enough inductance that the ripple can be ignored and it can be regarded as providing a DC current I L , and the flying capacitor C F1 , C F2 With output capacitor C O The capacitance is much larger than the resonant capacitor C R1 and resonant capacitor C R2 , which is approximately a DC voltage, and therefore does not participate in resonance. It can be found that the two resonant slots are completely equivalent, and the resonant frequency depends only on the parameters of the self-resonant element. When L R1 C R1 = L R2 C R2 When , the resonant frequencies of the two resonant tanks are equal, so when the proposed resonant switched capacitor topology circuit operates at this frequency, the two resonant tanks can realize soft switching at the same time. This resonant frequency is:

[0044] ;

[0045] Among them, L R is the resonant inductance value, C R is the resonant capacitance value, it can be seen that the second resonant frequency value of the multiple resonant slot units only depends on the parameter values ​​of the resonant inductance and resonant capacitance in the resonant slot unit. Here is a T SW =T R special case, Figure 6 It is worth mentioning that the present invention includes but is not limited to this special case, and can determine the respective operating frequencies to optimize the performance according to the selected voltage regulation level or resonant topology. Among them, the voltage drop of the resonant capacitor is a DC voltage superimposed with a small sinusoidal AC ripple, and the DC voltage is 3 times the output voltage (3V O ) with 1 times the output voltage (V O ).

[0046] Since the resonant capacitor voltage is only related to the output voltage and has nothing to do with the input voltage, and the output voltage is a constant low voltage in practical applications, the resonant capacitor voltage is sufficiently reduced, so that the capacitance attenuation amplitude of each of the two resonant capacitors is sufficiently reduced when using Class II ceramic capacitors, and it is easier to achieve the nominal value of the capacitor; in addition, the voltage difference between the two resonant capacitors is also reduced. Taking the output voltage as 3.3V and the capacitor using Murata GRM31CR72A105KA01 as an example, there is only a 4% capacity deviation between the two resonant capacitors. Compared with the traditional two-stage architecture, the resonant capacitor voltage in the present invention is only related to a specific output voltage and reduces the DC voltage difference of the resonant capacitor between the two resonant tanks, avoiding the large attenuation range of the resonant capacitor under a wide input voltage range and the attenuation mismatch caused by the resonant tank voltage difference. Therefore, only low-cost, high-capacitance density Class II ceramic capacitors are needed to achieve the insensitivity of the resonant frequency to the wide input voltage, saving complex frequency calibration or zero-current switching control circuits, reducing costs and improving power density.

[0047] The resonant switch capacitor topology circuit in the architecture of the present invention includes but is not limited to the large conversion ratio structure proposed by the present invention. Based on the form of the present architecture, any resonant network can be used between the node SW1 and the output load, and the voltage of the resonant capacitor is only related to the constant low voltage V O Both can achieve a resonant frequency that is insensitive to input voltage and use Class II ceramic capacitors to achieve low cost and high density.

[0048] The key points of the present invention are: 1. The proposed adjustable voltage resonant switch capacitor converter architecture consists of a voltage regulating stage and a resonant switch capacitor topology circuit. In this architecture, the voltage regulating stage withstands a high input voltage of 36V-60V, and the voltage domain is separated by a power inductor, so that the resonant switch capacitor topology circuit is only related to the output voltage and has nothing to do with the input voltage, and the DC voltage difference of the resonant capacitor between the two resonant tanks is reduced, avoiding the large attenuation range of the resonant capacitor under a wide input voltage range and the attenuation mismatch caused by the resonant tank voltage difference. Therefore, under the condition of using only Class II ceramic capacitors, the capacity attenuation of each resonant capacitor caused by the bias voltage and the mismatch between the two resonant tanks can be fully alleviated, reducing the implementation cost, improving the power density, while avoiding the change of the resonant frequency with the wide input voltage, saving complex frequency calibration or zero current switch control circuits. 2. The resonant switch capacitor topology circuit in the proposed architecture includes but is not limited to the specific structure given by the present invention. By means of the form of this architecture, any resonant network can achieve a resonant frequency that is insensitive to the input voltage and use Class II ceramic capacitors. 3. Compared with the traditional two-stage architecture of the cascade Buck of the switch slot converter (resonant switch capacitor converter), the present invention implements a resonant switch capacitor converter with adjustable voltage in the form of a single-stage architecture, which saves the decoupling capacitor required for the intermediate DC bus voltage, and the power inductor current is reduced to 1 / 6.5 of the output current, which fully reduces the DCR conduction loss, making it easier for the system to use small-size inductors, and is suitable for high-efficiency, high-density power conversion application scenarios. 4. Compared with the 4:1 switch slot converter, the resonant switch capacitor topology circuit introduces an additional switch to realize the charge transfer amplification of the two resonant slots and the flying capacitor, which improves the utilization rate of passive devices without adding additional passive devices, and the voltage conversion ratio is increased to 6.5:1, effectively extending the conduction time.

[0049] So far, the embodiments of the present disclosure have been described in detail in conjunction with the accompanying drawings. It should be noted that the implementation methods not shown or described in the drawings or the body of the specification are all forms known to ordinary technicians in the relevant technical field and are not described in detail. In addition, the above definitions of each element and method are not limited to the various specific structures, shapes or methods mentioned in the embodiments, and ordinary technicians in the field can simply change or replace them.

[0050] It should be noted that, in this document, unless otherwise specified, “a” element is not limited to a single element, but may include one or more elements.

[0051] In addition, in this document, unless otherwise specified, ordinal numbers such as "first" and "second" are only used to distinguish multiple components with the same name, and do not indicate that there is a hierarchy, level, execution order, or process order between them. A "first" component and a "second" component may appear together in the same component, or appear in different components. The presence of a component with a larger ordinal number does not necessarily indicate the presence of another component with a smaller ordinal number.

[0052] In this document, unless otherwise specified, the so-called feature A "or" or "and / or" (and / or) feature B means that A exists alone, B exists alone, or A and B exist at the same time; the so-called feature A "and" (and) or "and" (and) or "and" (and) feature B means that A and B exist at the same time; the so-called "include", "comprise", "have" and "contain" mean including but not limited to these.

[0053] In addition, in this document, the terms "upper", "lower", "left", "right", "front", "back", or "between" are only used to describe the relative positions between multiple elements, and can be extended to include translation, rotation, or mirroring. In addition, in this document, unless otherwise specified, "an element is on another element" or similar descriptions do not necessarily mean that the element contacts the other element.

[0054] In addition, unless the steps are specifically described or must occur in sequence, the order of the above steps is not limited to the above list, and can be changed or rearranged according to the required design. And the above embodiments can be mixed and matched with each other or with other embodiments based on design and reliability considerations, that is, the technical features in different embodiments can be freely combined to form more embodiments.

[0055] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A voltage-adjustable resonant DC-DC converter, comprising: A voltage regulating stage is connected to the input terminal and is configured to operate at a first frequency to control the charging and demagnetization of a power inductor in the voltage regulating stage; A resonant switched capacitor topology circuit is connected to the end of the inductor in the voltage regulation stage and forms a high-low level switching node at the connection. The switched capacitor topology circuit includes a plurality of resonant tank units, and the plurality of resonant tank units operate at a second frequency of resonance, so that the voltage at the high-low level switching node switches between a high multiple value and a low multiple value of a specific output voltage, thereby realizing soft switching of the switched capacitor topology circuit.

2. The adjustable voltage resonant DC-DC converter according to claim 1, wherein the frequency value of the second frequency is higher than the frequency value of the first frequency.

3. The voltage-adjustable resonant DC-DC converter according to claim 1, wherein the voltage-adjusting stage comprises a high-side tube S H , low side tube S L , power inductor L, where: High side tube S H One end is connected to the input end, and the other end is connected to the first end a of the power inductor L. The high-side tube S H A node SW0 is set between the power inductor L and the low-side tube S L The node SW0 is connected to ground.

4. According to the adjustable voltage resonant DC-DC converter of claim 1, each resonant tank unit comprises a flying capacitor, a power switch, and a resonant tank, and the voltage at the high-low level switching node is switched between a high multiple value and a low multiple value of a specific output voltage by connecting and disconnecting different power switches in a linked manner. 5 . The voltage-adjustable resonant DC-DC converter according to claim 4 , comprising two resonant tank units, namely a first resonant tank unit and a second resonant tank unit.

6. The adjustable voltage resonant DC-DC converter according to claim 5, wherein the first resonant tank unit comprises a power switch S1, a power switch S2, a power switch S3, a power switch S4, a power switch S5, a power switch S6, a flying capacitor C F1 , resonant inductor L R1 , resonant capacitor C R1 , resonant inductor L R1 and resonant capacitor C R1 Constitute a first resonant tank; wherein, One end of the power switch S1 is connected to the second end b of the power inductor L in the voltage regulation stage via the high-low level switching node SW1, and the other end of the power switch S1 is connected to the power switch S2 via the node SW3. The high-low level switching node SW1 is connected to the flying capacitor C F1 Then it is connected to the ground through the node SW2 and the power switch S6, and the node SW3 is connected to the resonant capacitor C R1 , resonant inductor L R1 Then it is grounded through node SW4 and power switch S4. The other side of node SW4 is connected to power switch S3 and power switch S5 and then to node SW2. Power switch S2 is then connected to power switch S5 and then to node SW2.

7. The voltage-adjustable resonant DC-DC converter according to claim 6, wherein the second resonant tank unit comprises a power switch S7, a power switch S8, a power switch S9, a power switch S 10 , power switch S 11 , power switch S 12 , flying capacitor C F2 , resonant inductor L R2 , resonant capacitor C R2 , resonant inductor L R2 and resonant capacitor C R2 Constitute a second resonant tank; wherein, One end of the power switch S7 is connected to the first resonant tank unit via the node SW5, and the other end of the power switch S7 is connected to the power switch S8 via the node SW7. The node SW5 is connected to the flying capacitor C F2 Then it is connected to the ground through the node SW6 and the power switch S12, and the node SW7 is connected to the resonant capacitor C R2 , resonant inductor L R2 The node SW8 is then connected to the ground via the power switch S10. The other side of the node SW8 is connected to the power switch S9 and the power switch S 11 Then connected to node SW2, power switch S8 is connected to power switch S 11 And connected to node SW6.

8. The adjustable voltage resonant DC-DC converter according to claim 6, wherein: The resonant switched capacitor topology circuit operates at a second frequency and a 50% duty cycle; In half cycle, power switches S1, S3, S6, S7, S9, S 12 Disconnect, power switches S2, S4, S5, S8, S 10 , S 11 conduction, power inductor L to flying capacitor C F1 Charging, the first resonant tank discharges, the flying capacitor C F2 At the same time, the resonant capacitor C F1 The two paths of the first resonant tank are charged, and at the same time the second resonant tank is also discharged; the flying capacitor C F2 The second resonant tank is connected in parallel to charge the load; according to Kirchhoff's voltage law, the DC voltage of each flying capacitor can be calculated: V CF1 =5V O , V CF2 =2V O ; The voltage at the high-low level switching node SW1 rises to a high voltage V H , V H =V CF1 + V CF2 + V O =8V O , where V CF1 Represents the flying capacitor C F1 Voltage, V CF2 Represents the flying capacitor C F2 Voltage, V O Indicates the load voltage.

9. The adjustable voltage resonant DC-DC converter according to claim 8, wherein: In the other half cycle, the power switches S1, S3, S6, S7, S9, S 12 Turn on, power switches S2, S4, S5, S8, S 10 , S 11 Disconnect, power inductor L and flying capacitor C F1 The first resonant tank is charged in parallel, while the second resonant tank is connected in series with the load and connected by the first resonant tank and the flying capacitor C F2 Connect it in parallel to charge it, the flying capacitor C F1 And the flying capacitor C F2 Discharge, the voltage at the high-low level switching node SW1 drops to a low voltage V L , V L =V CF1 =5V O .

10. The voltage-adjustable resonant DC-DC converter according to claim 1, wherein the second resonant frequency value of the plurality of resonant tank units only depends on the parameter values ​​of the resonant inductor and the resonant capacitor in the resonant tank unit.

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