Fast transient response dual-channel buck converter and control method

Abstract

The invention provides a fast transient response dual-channel buck converter and a control method. The fast transient response dual-channel buck converter comprises an input module, a flying capacitor, a first inductor, a third switching device, a second inductor and a dual-phase charging control module, wherein the input end of the flying capacitor is connected with the input module; the input end of the first inductor is connected with the output end of the flying capacitor; the drain electrode of the third switching device is electrically connected with the input end of the first inductor; the input end of the second inductor is electrically connected with the source electrode of the third switching device; the double-phase charging control module is connected in parallel between the output end of the flying capacitor and the source electrode of the third switching device and is used for realizing a double-phase charging function; the output end of the first inductor is electrically connected with the output end of the second inductor and is used as an output power supply. According to the invention, only two switches need to be added, so that the load can be optimized from light load to heavy load and from heavy load to light load at the same time, and the manufacturing difficulty and cost are reduced.

Description

Technical Field

[0001] The present application relates to the field of electronic technology, and in particular to a fast transient response dual-channel buck converter and a control method. Background Art

[0002] The surge in data center applications, a direct result of the explosive growth of big data, cloud computing, and the Internet of Things, presents significant architectural and design strategy challenges for modern power supply technologies. Traditionally, a two-stage 48V / 12V / 1V architecture has been used at the end of the power transmission chain. This typically consists of two DC-DC power conversion stages: an intermediate bus converter that converts 48V to 12V, and a point-of-load converter that converts the 12V to a well-regulated 1V suitable for the load. This architecture has the advantage of being widely adopted for many years. While both stages have undergone continuous improvements and the design technology is quite mature, further improvements in efficiency and performance have been limited.

[0003] Dual-step-down (DSD) converters are suitable candidates because they can provide a 2× duty cycle expansion and a 2× equivalent switching frequency while reducing the voltage stress on the power transistors by simply adding a capacitor across the two-phase buck converter. However, robustly controlling DSD converters to achieve fast transient response remains challenging. Hysteretic control is widely used in buck converters due to its simple structure and fast response. However, applying hysteretic control to DSD converters may not be feasible because the on-time of the two phases must have a 180° phase shift and cannot overlap.

[0004] When load switching occurs in traditional PWM control, there is an inherent delay, which results in large overshoot and overshoot voltages. Existing delay-insensitive DSD converters with dual-phase charging technology solve the problem of load switching from light to heavy loads. However, to achieve dual-phase charging, two switches are added to the inductor input to implement this path, increasing manufacturing costs.

[0005] Therefore, a cost-effective dual-channel buck converter with fast transient response is particularly needed. Summary of the Invention

[0006] The purpose of the present application is to provide a dual-channel buck converter with fast transient response and a control method to at least solve one technical problem in the prior art.

[0007] The technical solution of this application is:

[0008] A fast transient response dual-channel buck converter comprising:

[0009] Input module, used to connect input power;

[0010] a flying capacitor, an input end of which is connected to the input module;

[0011] a first inductor, an input end of which is connected to the output end of the flying capacitor;

[0012] a third switching device, a drain of which is electrically connected to the input end of the first inductor;

[0013] a second inductor, an input end of which is electrically connected to the source of the third switching device;

[0014] A dual-phase charging control module is connected in parallel between the output terminal of the flying capacitor and the source of the third switching device to realize the dual-phase charging function;

[0015] The output end of the first inductor is electrically connected to the output end of the second inductor and is used as an output power supply.

[0016] The input module comprises:

[0017] a first switching device, a drain of which is connected to the input power supply, and a source of which is electrically connected to the input end of the first inductor;

[0018] a fifth switching device, a drain of which is electrically connected to the source of the first switching device;

[0019] A source of the fifth switching device is grounded.

[0020] The dual-phase charging control module includes:

[0021] a second switching device, a drain of which is electrically connected to the output terminal of the flying capacitor;

[0022] a fourth switching device, a drain of which is electrically connected to the input end of the second inductor;

[0023] a sixth switching device, one end of which is connected to the source of the fourth switching device;

[0024] a substrate selection circuit, electrically connected to the sixth switching device;

[0025] The source of the second switching device is electrically connected to the source of the fourth switching device.

[0026] A third switching device is provided between the drain of the fourth switching device and the source of the first switching device, for optimizing the load switching problem from heavy load to light load.

[0027] The drain of the third switching device is connected to the source of the first switching device;

[0028] The source of the third switching device is connected to the drain of the fourth switching device.

[0029] The second switching device and the fourth switching device are both provided with parasitic diodes in opposite directions to prevent leakage.

[0030] The fast transient response dual-channel buck converter further includes:

[0031] The load capacitor has one end electrically connected to the output power supply and the other end grounded.

[0032] A fast transient response dual-channel buck conversion control method is based on the fast transient response dual-channel buck converter as described above, comprising:

[0033] When a load change is detected, a first signal or a second signal is output;

[0034] When the output is the first signal, the first switch device, the second switch device, and the fourth switch device are turned on, and the third switch device, the fifth switch device, and the sixth switch device are turned off; the input voltages of the first inductor and the second inductor are both V in / 2; continue to supply current to the two inductors to reduce the undershoot time; V in is the input voltage;

[0035] When the second signal is output, the second switch device, the fourth switch device and the fifth switch device are turned on, and the first switch device, the third switch device and the sixth switch device are turned off; the input voltage of the first inductor and the second inductor is -V in / 2, the output voltage is V out , which increases the slope of the inductor current drop and reduces the uprush time; V out is the output voltage.

[0036] In steady-state operation, the fifth switch device is always in the on state, and the sixth switch device is always in the off state. It only works when the load is switched, and no additional switching loss is added.

[0037] A flying capacitor is provided at the input end of the first inductor so that the terminal voltage of the first inductor is negative, thereby optimizing the situation of heavy load to light load conversion.

[0038] The beneficial effects of this application include at least:

[0039] The fast transient response dual-channel buck converter described in this application utilizes the circuit structure of a traditional DSD converter and only needs to add one switching device to achieve the dual-phase charging function; and another switching device is added to ground, using the flying capacitor C FTo reduce the voltage at the inductor input end, the load switching problem from heavy load to light load can be optimized; the present invention only needs to add two switches to simultaneously optimize the load switching from light load to heavy load and heavy load to light load, reducing the manufacturing difficulty and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a traditional DSD converter circuit diagram;

[0041] Figure 2 It is a DSD converter with delay insensitivity and dual-phase charging technology in the existing technology;

[0042] Figure 3 This is a circuit diagram of a dual-channel buck converter with fast transient response according to the present invention;

[0043] Figure 4 yes Figure 3 Working state diagram of the circuit diagram;

[0044] Figure 5 yes Figure 3 Comparison of load transient responses of circuit diagrams;

[0045] Figure 6 yes Figure 3 State diagram of the circuit diagram in steady state. DETAILED DESCRIPTION

[0046] The present application will be further described below with reference to the accompanying drawings.

[0047] In order to describe the present application in more detail, it is necessary to describe the prior art in detail.

[0048] like Figure 1 The figure shows a traditional DSD converter with only one capacitor added to the traditional Buck converter. The DSD converter is very similar to the interleaved traditional Buck converter, except that the duty cycle of the high-side switch is doubled, the voltage stress of the switch is half that of the switch in the buck converter, the inductor current balance is automatic, and the inductor current ripple is reduced. However, during load switching, if it occurs during the on-time of CLK1, the loop will respond immediately to increase the duty cycle to increase the inductor current, thereby achieving a near-optimal response. However, if the transient occurs after the falling edge of PWM1, the loop will not respond until CLK2 becomes "1". Depending on the conversion ratio of the converter, the delay T d Such a delay will result in larger overshoot and overshoot voltages, especially when the load current step is large.

[0049] like Figure 2, is a voltage mode controlled DSD converter with delay insensitivity and dual-phase charging technology in the prior art to improve transient response. It solves the inherent delay of up to half a switching cycle when the load is switched. This structure adds a compensator, in which V ea and V gm A transient detection circuit is designed based on the different response speeds. gm By having a built-in offset V os The OTA buffer is then connected to the V ea Comparison is performed to generate a transient detection signal V tran In steady state, due to the addition of V os , V tran When the load current increases, once V ea Swing higher than V gm +V os , V tran becomes "1", PWM1 is set to "1" without waiting for the next clock signal. Therefore, an immediate response of extending the on-time can be achieved, thus avoiding the delay caused by T d caused by degradation.

[0050] In the prior art, Figure 1 Traditional DSD converters require two control signals, both of which have a 180° phase shift and cannot overlap, so hysteresis control is obviously not applicable. When load switching occurs in traditional PWM control, there is an inherent cycle delay, which will result in large overshoot and undershoot voltages. Figure 2 While delay-insensitive DSD converters with dual-phase charging technology address the light-to-heavy load switching issue, they don't address the heavy-to-light load switching issue. Furthermore, to achieve dual-phase charging, two switches are added to the inductor input, increasing manufacturing costs. Specific embodiment 1:

[0052] The present invention provides an embodiment:

[0053] Aiming at the problem that the DSD converter with delay insensitivity and dual-phase charging technology cannot process heavy load to light load at the same time, the present invention proposes a dual-channel buck converter with fast transient response, such as Figure 3 As shown, it consists of six NMOS switching devices, a flying capacitor, and two inductors. L Note that in this embodiment, the first switch device is S1, the second switch device is S2, and so on until the sixth switch device is S6. The source of S1 is connected to the flying capacitor C F The upper plate and drain of S3 and S5, the drain is connected to the input voltage V inThe source of S2 is connected to the source of S4 and S6, and the drain is connected to the flying capacitor C F The lower plate of S3 and one end of the inductor L1; the source of S3 is connected to the drain of S4 and one end of the inductor L2, and the drain is connected to the flying capacitor C F The upper plate of S1, the source of S1 and the drain of S5; the source of S4 is connected to the source of S2 and S6, and the drain is connected to the source of S3 and one end of the inductor L2; the source of S5 is grounded, and the drain is connected to the source of S1, the drain of S3 and the flying capacitor C F The upper plate of S6; S6 adds a substrate selection circuit, one end of which is connected to the ground level and the other end is connected to the source of S2 and S4.

[0054] The working principle of this embodiment is: when a load change is detected, V is output through EA and Cmp. up or V down Signal:

[0055] When the output is V up When the signal is on, enter Figure 4 In state 1 (a), the switching devices S1, S2, and S4 are turned on, and the switching devices S3, S5, and S6 are turned off. At this time, the voltage on the left side of the inductor L1 and L2 is V in / 2, in this state, current is continuously supplied to the two inductors to reduce the undershoot time.

[0056] When the output is V down When the signal is on, enter Figure 4 In state 2 (b), the switching devices S2, S4, and S5 are turned on, and the switching devices S1, S3, and S6 are turned off. At this time, the voltage on the left side of the inductor L1 and L2 is -V in / 2, the voltage on the right is V out , the voltage difference on both sides of the inductor increases, which can increase the slope of the inductor current decrease and reduce the uprush time.

[0057] This embodiment adds two switching devices to continuously charge the inductor in state one and speed up the discharge of the inductor in state two, so as to achieve transient response during load switching. Figure 2 Compared with the existing technology, the invention not only optimizes the transient response speed in the case of light load to heavy load, but also optimizes the case of heavy load to light load. In addition, in addition to optimizing the transient response, the structure of the invention also utilizes the switching devices S2 and S4, whose sources are connected together, so the directions of the parasitic diodes of the two MOS tubes are opposite, which can avoid the occurrence of leakage.

[0058] like Figure 5 As shown in (a), if the load jump occurs during the PWM on-time, the loop will respond immediately to increase the duty cycle to increase the inductor current, thereby achieving a near-optimal response. Figure 5As shown in (b), if the transient occurs after the falling edge of PWM1, the loop will not respond before CLK2 becomes "1", and there will be a certain amount of T d The structure of the present invention is similar to that proposed in the cited literature, so it is also not affected by the above T d When load switching is detected, V tran and V up The rising state becomes "1" and enters a specific phase to switch the load, which has a fast transient response. However, in the case of heavy load to light load, the referenced literature is not optimized, and its transient response is similar to that of traditional DSD, and is also affected by a certain amount of T d Impact, such as Figure 5 (c) As shown. The present invention has made a targeted optimization for this load conversion situation. When it is detected that the heavy load is converted to light load, V down It rises to "1" and enters a specific phase to switch the load, so there will be a more obvious transient response difference.

[0059] Figure 6 This is the state diagram of the present invention in steady state. Its working phase in steady state is As can be seen from the figure, in steady-state operation, S5 and S6 do not change between on and off. S5 is always in the on state, and its substrate is also connected to the ground terminal. S6 is always in the off state. These two switches only work when the load is switched, so there is no additional switching loss.

[0060] and Figure 2 Compared with the corresponding delay-insensitive and dual-phase charging technology DSD converter, this embodiment uses the two low-voltage side switches on the DSD converter structure to charge, and only adds one additional switch to achieve the same function; when the load is switched, the sources of the switch devices S2 and S4 are connected together, and the directions of the parasitic diodes of the two switch tubes are opposite, which can avoid the leakage phenomenon; not only the transient response speed under light load to heavy load conditions is optimized, but also the flying capacitor C is used to achieve the same effect. F The voltage at the terminal of the inductor 1 is negative, which optimizes the situation of heavy load to light load conversion. It can be seen that the fast transient response dual-channel buck converter described in this embodiment can use the switches of the traditional dual-channel buck (DSD) converter to realize the dual-phase charging technology; and use the flying capacitor C F The voltage at one end of the inductor is created to be negative, which optimizes the transient response from heavy load to light load; moreover, the sources of the two switching tubes are connected so that their parasitic diodes are in opposite directions, avoiding leakage. Specific embodiment 2:

[0062] A fast transient response dual-channel buck converter control method, based on the fast transient response dual-channel buck converter described in specific embodiment 1, includes: when a load change is detected, outputting a first signal or a second signal; when the first signal is output, the first switching device, the second switching device, and the fourth switching device are turned on, and the third switching device, the fifth switching device, and the sixth switching device are turned off; the input voltages of the first inductor and the second inductor are both V in / 2; continue to supply current to the two inductors to reduce the undershoot time; V in is the input voltage; when the output is the second signal, the second switch device, the fourth switch device and the fifth switch device are turned on, and the first switch device, the third switch device and the sixth switch device are turned off; the input voltage of the first inductor and the second inductor is -V in / 2, the output voltage is V out , which increases the slope of the inductor current drop and reduces the uprush time; V out is the output voltage.

[0063] In steady-state operation, the fifth switch device is always in the on state, and the sixth switch device is always in the off state. It only works when the load is switched, and no additional switching loss is added.

[0064] A flying capacitor is provided at the input end of the first inductor so that the terminal voltage of the first inductor is negative, thereby optimizing the situation of heavy load to light load conversion. Specific embodiment 3:

[0066] This application also provides an embodiment:

[0067] An electronic device comprises: a storage medium and a processing unit; wherein the storage medium is used to store a computer program, and the processing unit exchanges data with the storage medium, and is used to execute the computer program through the processing unit when performing dual-channel buck conversion control, and perform the steps of the fast transient response dual-channel buck conversion control method as described in specific embodiment 2. Specific embodiment 4:

[0069] A computer-readable storage medium stores a computer program; when the computer program is run, the computer program executes the steps of the fast transient response dual-channel buck conversion control method as described in specific embodiment 2.

[0070] In this application, a computer-readable storage medium may be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. Furthermore, in this application, a computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, which carries computer-readable program code. This propagated data signal may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium that can transmit, propagate, or transfer a program for use by or in conjunction with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium may be transmitted using any suitable medium, including but not limited to wireless, wire, optical cable, RF, etc., or any suitable combination thereof.

[0071] The above disclosures are only a few specific implementation scenarios of this application, but this application is not limited to them. Any changes that can be thought of by those skilled in the art should fall within the scope of protection of this application. The above application numbers are for descriptive purposes only and do not represent the advantages or disadvantages of the implementation scenarios.

Claims

1. A fast transient response dual-channel buck converter, characterized in that: include: Input module, used to connect input power; A flying capacitor, an input end of which is connected to the input module; A first inductor, an input end of which is connected to an output end of the flying capacitor; a third switch device, a drain of which is electrically connected to the input end of the first inductor; A second inductor, an input end of which is electrically connected to the source of the third switching device; A two-phase charging control module is connected in parallel between the output end of the flying capacitor and the source of the third switch device to realize the two-phase charging function; The output end of the first inductor is electrically connected to the output end of the second inductor and is used as an output power supply.

2. The fast transient response dual-channel buck converter according to claim 1, characterized in that: The input module comprises: a first switch device, a drain of which is connected to the input power supply, and a source of which is electrically connected to the input end of the first inductor; a fifth switching device, a drain of which is electrically connected to the source of the first switching device; A source of the fifth switching device is grounded.

3. The fast transient response dual-channel buck converter according to claim 1, characterized in that: The dual-phase charging control module comprises: A second switch device, a drain of which is electrically connected to the output end of the flying capacitor; a fourth switch device, a drain of which is electrically connected to the input end of the second inductor; a sixth switching device, one end of which is connected to the source of the fourth switching device; a substrate selection circuit, electrically connected to the sixth switch device; A source of the second switching device is electrically connected to a source of the fourth switching device.

4. The fast transient response dual-channel buck converter according to claim 3, characterized in that: A third switch device is provided between the drain of the fourth switch device and the source of the first switch device, so as to optimize the load switching problem from heavy load to light load.

5. The fast transient response dual-channel buck converter according to claim 4, characterized in that: The drain of the third switching device is connected to the source of the first switching device; The source of the third switching device is connected to the drain of the fourth switching device.

6. The fast transient response dual-channel buck converter according to claim 3, characterized in that: The second switch device and the fourth switch device are both provided with parasitic diodes in opposite directions to prevent leakage.

7. The fast transient response dual-channel buck converter according to claim 1, characterized in that: Also includes: The load capacitor has one end electrically connected to the output power supply and the other end grounded.

8. A fast transient response dual-channel buck conversion control method, based on the fast transient response dual-channel buck converter according to any one of claims 1 to 6, characterized in that: include: When a load change is detected, a first signal or a second signal is output; When the output is the first signal, the first switch device, the second switch device, and the fourth switch device are turned on, and the third switch device, the fifth switch device, and the sixth switch device are turned off; the input voltages of the first inductor and the second inductor are both V in / 2; continue to supply current to the two inductors to reduce the undershoot time; V in is the input voltage; When the output is the second signal, the second switch device, the fourth switch device and the fifth switch device are turned on, and the first switch device, the third switch device and the sixth switch device are turned off; the input voltages of the first inductor and the second inductor are both -V in / 2, the output voltage is V out , which increases the slope of the inductor current drop and reduces the uprush time; V out is the output voltage.

9. The fast transient response dual-channel buck conversion control method according to claim 8, characterized in that: include: In steady-state operation, the fifth switch device is always in an on state, and the sixth switch device is always in an off state, and only works when the load is switched, and no additional switching loss is added.

10. The fast transient response dual-channel buck conversion control method according to claim 8, characterized in that: A flying capacitor is arranged at the input end of the first inductor so that the terminal voltage of the first inductor is a negative value, thereby optimizing the situation of heavy load conversion to light load.

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