Adjustable Voltage Resonant DC-DC Converter

Abstract

The present disclosure provides a wide-input-range, adjustable-voltage resonant DC-DC converter, comprising: a voltage-regulating stage connected to an input terminal and configured to operate at a first frequency to control the charging and demagnetization of a power inductor in the voltage-regulating stage; and a resonant switched-capacitor topology circuit connected to the ends of the inductor in the voltage-regulating stage and forming a high-low level switching node at the connection. The switched-capacitor topology circuit includes a plurality of resonant tank units that operate at a resonant second frequency, such that the voltage at the high-low level switching node switches between a high multiple and a low multiple of a specific output voltage, thereby achieving soft switching of the switched-capacitor topology circuit.

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] The Switched Tank Converter (STC), a resonant switched-capacitor DC-DC converter, is primarily used in next-generation servers with high bus voltages (48V) and other high-power applications. Based on the resonant operation of inductors and capacitors, it performs voltage conversion, achieving high efficiency and high power density at a fixed conversion ratio (primarily a 4:1 ratio), thereby generating an intermediate bus voltage of 12V. In servers, multiple modules and subsystems, such as I / O interfaces, memory modules, and air cooling systems, require a stable, lower voltage power supply (such as 5V or 3.3V) to ensure normal operation. Therefore, an additional, adjustable step-down DC-DC converter (Buck) is often required to further reduce the voltage from 12V to 3.3V-5V.

[0003] However, this two-stage STC + Buck architecture presents two major issues. First, as a resonant switched-capacitor DC-DC converter, the STC requires operation at a specific resonant frequency to achieve soft switching of the power devices for high efficiency. Therefore, the converter relies on maintaining stable parameters for the resonant capacitor or inductor. Because the DC voltage across the resonant capacitor is dependent on the input voltage, Class I ceramic capacitors offer advantages over Class II capacitors in terms of high stability, precision, and voltage insensitivity, making them suitable for resonant switched-capacitor DC-DC converters to achieve stable capacitance over a wide input voltage range. However, they suffer from low capacitance density and high price, often requiring multiple capacitors to be connected in parallel, increasing cost and reducing power density. Class II ceramic capacitors also exhibit significant capacitance degradation with DC bias, causing the resonant frequency to shift with input voltage. Second, the power inductor used for voltage regulation in the two-stage architecture is located at the output and must withstand a DC current equal to the load current. Consequently, the inductor's direct current resistance (DCR) conduction losses are high, limiting system efficiency. 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 resonant DC-DC converter with a wide input range and adjustable voltage.

[0005] In order to achieve the above objectives, the technical solutions disclosed in this disclosure are as follows:

[0006] According to an embodiment of the present disclosure, there is provided a voltage-adjustable 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, wherein the switched capacitor topology circuit comprises a plurality of resonant tank units, and the plurality of resonant tank units operate 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 Connect node SW0 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 the linkage on and off of different power switches.

[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 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 The first resonant tank is formed; wherein, one end of the power switch S1 is connected to the second end b of the power inductor L in the voltage regulating 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, and the high-low level switching node SW1 is connected to the flying capacitor C F1 Then it passes through node SW2 and power switch S6 and is grounded. Node SW3 is connected to resonant capacitor C R1 , resonant inductor L R1Then it is connected to the ground through the node SW4 and the power switch S4. The other side of the node SW4 is connected to the power switch S3 and the power switch S5 and then to the node SW2. The power switch S2 is then connected to the power switch S5 and then to the node SW2.

[0012] According to an embodiment of the present disclosure, the second resonant tank unit includes 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 The second resonant tank is formed; wherein one end of the power switch S7 is connected to the first resonant tank unit via the node SW5, the other end of the power switch S7 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 passes through node SW6 and power switch S12 and is grounded. Node SW7 is connected to 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, power switch S8 is connected to 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 switches S1, S3, S6, S7, S9, and 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. 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, and the second resonant tank is connected in series with the load and connected to the flying capacitor C F2 Charge it in parallel, the flying capacitor C F1 and 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 two-stage switching slot converter in the prior art.

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

[0018] Figure 3 Schematic diagram of the principle structure of a two-stage switching slot converter in the prior art.

[0019] Figure 4 FIG. 1 is a circuit diagram of a voltage-adjustable resonant DC-DC converter according to an embodiment of the present disclosure.

[0020] Figure 5 Schematic diagram of different operating 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 operating states according to an embodiment of the present disclosure.

[0022] Figure 7 The figure is a schematic diagram of the working principle framework of the 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. Its resonant topology is only related to the output voltage and not the input voltage, and reduces the DC voltage difference of the resonant capacitor between the two resonant tanks, avoiding the wide 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-capacity-density Class II ceramic capacitors are required to achieve the insensitivity of the resonant frequency to a wide input voltage, eliminating the need for complex frequency calibration or zero-current switching control circuits, reducing costs and increasing power density. In addition, in this architecture, the inductor current is reduced to 1 / 6.5 of the output current, which fully reduces the DCR conduction loss, improves conversion efficiency, and increases the utilization rate of passive components, further improving the voltage conversion ratio.

[0024] Unlike switched capacitor converters, the STC in existing technologies uses an LC resonant tank to partially replace the flying capacitor 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 alternative to 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-end stage with a fixed conversion ratio of 4:1 to output 12V, and the back-end uses an adjustable voltage Buck to further step down the voltage to 3.3V-5V to power the server module and subsystem.

[0025] 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 IEEE Applied Power Electronics Conference and Exposition (APEC), Long Beach, CA, USA, Feb. 2024, pp. 1344–1350.], such as Figure 2 As shown, the efficiency improvement is achieved by reducing the required power switches.

[0026] The above two solutions can be equivalent to Figure 3 In the traditional two-stage architecture diagram in the upper part, the 48V bus input voltage typically has a wide range of 36V to 60V, taking into account factors such as the varying operating conditions of the uninterruptible power supply (UPS) in the rack, load fluctuations, and ambient temperature. Therefore, the first-stage STC performs a fixed 4:1 voltage conversion to produce an intermediate voltage of 9V to 15V. Regarding the selection of resonant capacitors, among commercially available surface-mount ceramic capacitors, Class I ceramic capacitors (materials including C0G and U2J) offer high stability, high precision, voltage insensitivity, low dielectric constant, low capacitance density, and high price. They are typically used in resonant circuits, high-frequency circuits, and temperature compensation circuits. Class II ceramic capacitors (materials including X7R and X7S) offer high dielectric constant, high capacitance density, low cost, and voltage sensitivity, and are typically used in power supply bypass or decoupling applications. For resonant switched capacitor DC-DC converters, it is generally necessary to operate at a specific resonant frequency to achieve soft switching of the power devices in order to achieve high efficiency. Therefore, the converter relies more on capacitors with stable capacitance and insensitivity to bias voltage. Considering that under a wide input voltage range, the bias voltage difference between the resonant capacitors in the two LC resonant tanks of the STC is large and varies widely, if Class II ceramic capacitors (such as Murata GRM31CR72A105KA01) are used, Figure 3As shown, the variation of a single resonant capacitor with the input voltage can be as high as 22%, and the capacitance difference between 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 slots respectively. Therefore, 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 low 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-stage Buck converter of the traditional two-stage architecture, since the power inductor for voltage regulation is located at the output end and needs to withstand a direct current flow equal to the load current, the DCR conduction loss of the inductor is high, deteriorating 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 (0 < D < 1) of the power switch control signal in the subsequent-stage Buck, the utilization rate of passive devices is insufficient, and the equivalent conduction time extension is limited, making it difficult to achieve an output with a larger conversion ratio.

[0028] It can be seen that in the two-stage architecture of the traditional STC+ Buck, the DC voltage of the resonant capacitor is related to the input voltage. For the application scenario of a wide input voltage, this architecture strongly depends on Class I ceramic capacitors with a constant capacitance as the resonant capacitor to obtain a constant resonant frequency to achieve high efficiency. Therefore, the cost is high and the power density is low. In addition, the DC current of the power inductor for voltage regulation is equal to the load current, the DCR conduction loss of the inductor is high, the system conversion efficiency is low, and the utilization rate of passive devices is insufficient, making it difficult to achieve an output with a larger conversion ratio.

[0029] Based on the above disadvantages, the present invention provides an adjustable resonant DC-DC converter with a wide input voltage range. The voltage of its resonant capacitor is only related to a specific output voltage and reduces the DC voltage difference between the resonant capacitors of the two resonant slots, avoiding the problems of large attenuation range of the resonant capacitor and attenuation mismatch caused by the voltage difference of the resonant slots in a wide input voltage range. Therefore, only low-cost and high-capacitance-density Class II ceramic capacitors are needed to achieve the insensitivity of the resonant frequency to a wide input voltage, saving complex frequency calibration or zero-current switching control circuits, reducing costs and increasing power density. In addition, the inductor current in this architecture is reduced to 1 / 6.5 of the output current, fully reducing the DCR conduction loss, improving the conversion efficiency, relaxing the demand for large-size, small-DCR, and high-saturation-current inductors; and improving the utilization rate of passive devices. 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 larger 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 conjunction 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] 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 multiple resonant tank units, and the multiple resonant tank units operate at a second resonant 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.

[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. H and low border 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 consists of a low-voltage power switch, a flying capacitor, a resonant inductor, and a resonant capacitor. Unlike the two-stage architecture, the connection node SW1 between the voltage regulation stage and the resonant switched capacitor topology circuit is not an intermediate DC voltage, but a switching 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, including but not limited to various voltage-resistant NMOS and 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 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 LEach 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 and a low multiple of a specific output voltage by switching on and off 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 Controlled by 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. 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 and will not be described in detail here.

[0037] Combine Figure 4 and Figure 5 、 Figure 7 As shown, the adjustable voltage resonant DC-DC converter includes two resonant tank units, namely the first resonant tank unit and the second resonant tank unit. The first resonant tank unit includes power switch S1, power switch S2, power switch S3, power switch S4, power switch S5, power switch S6, and 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, one end of the power switch S1 is connected to the second end b of the power inductor L in the voltage regulating 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, and the high-low level switching node SW1 is connected to the flying capacitor C F1 Then it passes through node SW2 and power switch S6 and is grounded. Node SW3 is connected to resonant capacitor C R1 , resonant inductor L R1 Then it is connected to the ground through the node SW4 and the power switch S4. The other side of the node SW4 is connected to the power switch S3 and the power switch S5 and then to the node SW2. The power switch S2 is then connected to the power switch S5 and then to the node SW2.

[0038] The second resonant tank unit includes power switch S7, power switch S8, power switch S9, power switch S 10 , power switch S 11 , power switch S 12 , flying capacitor C F2 , resonant inductor LR2 , resonant capacitor C R2 , resonant inductor L R2 and resonant capacitor C R2 The second resonant tank is formed; wherein one end of the power switch S7 is connected to the first resonant tank unit via the node SW5, the other end of the power switch S7 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 passes through node SW6 and power switch S12 and is grounded. Node SW7 is connected to 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, power switch S8 is connected to 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 the second frequency and the duty cycle is 50%.

[0040] In one half cycle (Φ R1 ), 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. In the other half cycle (Φ R2), 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, and the second resonant tank is connected in series with the load and connected to the flying capacitor C F2 Charge it in parallel, the flying capacitor C F1 and 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 switches between the two modes, and the duty cycle is 50%, so that the resonant network can be equivalent to generating a voltage conversion ratio of 6.5:1. The DC current of the power inductor is thereby reduced to 1 / 6.5 of the load current, effectively reducing the inductor DCR conduction loss and contributing to efficiency improvement.

[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 in the lower plate to control the charge and discharge state, which is used 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, it improves the utilization rate of capacitor devices without adding additional passive devices, and further improves the voltage conversion ratio from 4:1 to 6.5:1, thereby effectively extending the equivalent conduction time of the voltage regulation stage, 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 is large enough to ignore the ripple and regard it as providing a DC current I L , and the flying capacitor C F1 、C F2 With the 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 tanks 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. Therefore, 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 we give a T SW =T R special case, Figure 6 The key waveform diagram is as follows. It is worth mentioning that the present invention includes but is not limited to this special case. The respective operating frequencies can be determined according to the selected voltage regulation level or resonant topology to optimize the performance. Among them, the voltage drop of the resonant capacitor is represented by a DC voltage superimposed with a small sinusoidal AC ripple. 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 not to the input voltage, and the output voltage is a constant low voltage in actual applications, the resonant capacitor voltage is sufficiently reduced, so that when using Class II ceramic capacitors, the capacitance attenuation of each of the two resonant capacitors is sufficiently reduced, making it 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 of 3.3V and the capacitor using Murata GRM31CR72A105KA01 as an example, there is only a 4% capacitance 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 the 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 a wide input voltage, eliminating the need for complex frequency calibration or zero-current switching control circuits, reducing costs and improving power density.

[0047] The resonant switched capacitor topology circuit in the architecture of the present invention includes but is not limited to the large conversion ratio structure proposed in the present invention. Based on the form of this architecture, any resonant network can be used between the node SW1 and the output load, and the voltage of the resonant capacitor is only proportional 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 switched capacitor converter architecture consists of a voltage regulator stage and a resonant switched capacitor topology circuit. In this architecture, the voltage regulator stage withstands a high input voltage of 36V-60V, and the voltage domain is separated by a power inductor, so that the resonant switched capacitor topology circuit is only related to the output voltage and not to 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, and avoiding the change of the resonant frequency with a wide input voltage, saving the complex frequency calibration or zero current switching control circuit. 2. The resonant switched 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 to the traditional two-stage cascade Buck architecture of a switched-tank converter (resonant switched-capacitor converter), this invention implements a voltage-adjustable resonant switched-capacitor converter in a single-stage architecture. This eliminates the decoupling capacitors required for the intermediate DC bus voltage and reduces the power inductor current to 1 / 6.5 of the output current, significantly reducing DCR conduction losses. This facilitates the use of small-sized inductors and is suitable for high-efficiency, high-density power conversion applications. 4. Compared to the 4:1 switched-tank converter, the resonant switched-capacitor topology circuit introduces additional switches to amplify charge transfer between the two resonant tanks and the flying capacitors. This improves passive component utilization without adding additional passive components, increasing the voltage conversion ratio to 6.5:1 and effectively extending the on-time.

[0049] The embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. It should be noted that any implementations not depicted or described in the drawings or the main text of the specification are known to those skilled in the art and are not described in detail. Furthermore, the above definitions of the various elements and methods are not limited to the various specific structures, shapes, or methods described in the embodiments, and can be easily modified or replaced by those skilled in the art.

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

[0051] Furthermore, unless otherwise specified, ordinal numbers such as "first" and "second" are used herein solely to distinguish multiple components with the same name and do not imply a hierarchy, level, execution order, or process sequence between them. A "first" component and a "second" component may appear together in the same component or in different components. The presence of a component with a higher ordinal number does not necessarily imply the presence of the other component with a lower ordinal number.

[0052] In this document, unless otherwise specified, the so-called feature A "or" 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" or "and" or "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] Furthermore, in this document, terms such as "upper," "lower," "left," "right," "front," "back," or "between" are used solely to describe the relative positions of multiple elements and can be interpreted to include translation, rotation, or mirroring. Furthermore, 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] Furthermore, unless specifically described or required to occur sequentially, the order of the steps is not limited to the order listed above and may be varied or rearranged based on desired design requirements. Furthermore, the above embodiments may be mixed and matched with each other or with other embodiments based on design and reliability considerations. That is, the technical features of different embodiments may 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 are only specific embodiments of the present disclosure and are 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 scope of protection 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 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 regulator stage and forming a high-low level switching node at the connection, the switched capacitor topology circuit including two resonant tank units, namely a first resonant tank unit and a second resonant tank unit, the two resonant tank units operating at a second resonant frequency, so that the voltage at the high-low level switching node switches between a high multiple and a low multiple of the specific output voltage, thereby achieving soft switching of the switched capacitor topology circuit; The first resonant tank unit includes 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 The first resonant tank is formed; wherein, one end of the power switch S1 is connected to the second end b of the power inductor L in the voltage regulating 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, and the high-low level switching node SW1 is connected to the flying capacitor C F1 Then it passes through node SW2 and power switch S6 and is grounded. Node SW3 is connected to resonant capacitor C R1 , resonant inductor L R1 Then it passes through node SW4 and power switch S4 and is grounded. 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. The second resonant tank unit includes power switch S7, power switch S8, power switch S9, 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 one end of the power switch S7 is connected to the first resonant tank unit via the node SW5, the other end of the power switch S7 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 passes through node SW6 and power switch S12 and is grounded. Node SW7 is connected to 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, power switch S8 is connected to power switch S 11 And connected to node SW6. 2 . The adjustable voltage resonant DC-DC converter according to claim 1 , wherein the second frequency has a higher frequency than the first frequency.

3. The voltage-adjustable resonant DC-DC converter according to claim 1, wherein the voltage-regulating stage comprises a high-side transistor 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 Connect node SW0 to ground.

4. The adjustable voltage resonant DC-DC converter according to claim 1, wherein: The resonant switched capacitor topology circuit operates at a second frequency and a 50% duty cycle; In the half cycle, the power switch S1, power switch S3, power switch S6, power switch S7, power switch S9, power switch S 12 Disconnect, power switch S2, power switch S4, power switch S5, power switch S8, power switch S 10 , power switch 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.

5. The adjustable voltage resonant DC-DC converter according to claim 4, wherein: In the other half cycle, power switch S1, power switch S3, power switch S6, power switch S7, power switch S9, power switch S 12 On, power switch S2, power switch S4, power switch S5, power switch S8, power switch S 10 , power switch S 11 Disconnect, power inductor L and flying capacitor C F1 The first resonant tank is charged in parallel, and the second resonant tank is connected in series with the load and connected to the flying capacitor C F2 Charge it in parallel, the flying capacitor C F1 and 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 . 6 . The voltage-adjustable resonant DC-DC converter according to claim 1 , wherein the second resonant frequency value depends only on parameter values ​​of a resonant inductor and a resonant capacitor in the resonant tank unit.

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