Multi-phase DC-DC power converter and control method thereof

Abstract

The invention discloses a multi-phase DC-DC power converter and a control method thereof. The multiphase DC-DC power converter comprises: a plurality of switch modules; and the control circuit is used for providing driving signals for the first switch tube and the second switch tube of each switch module. The control circuit is configured to synchronously turn on the first switch tubes of the plurality of switch modules, and to synchronously turn on the second switch tubes of the plurality of switch modules after detecting that the first switch tubes of the plurality of switch modules are all turned off. The plurality of switch modules in the multi-phase DC-DC power converter share the external energy storage element so as to simplify the number of peripheral elements, and the driving current requirements of different loads can be met by starting any number of switch modules. Furthermore, shunting is realized and the overall efficiency of the system is improved through switching tube parameter matching of a plurality of switching modules, and output current ripples can be effectively reduced by adopting a synchronous control strategy.

Description

Technical Field

[0001] This article relates to switching power supply technology, and more specifically, to multiphase DC-DC power converters and their control methods. Background Technology

[0002] In DC-DC power converters, there are different application scenarios with varying requirements. In applications supplying power to multiple loads separately, a multi-phase independent power supply architecture is used, flexibly configuring the number of power phases according to the number of loads. In applications supplying power to a single load, a multi-phase parallel architecture is used, dynamically adjusting the output current capability according to load demand.

[0003] In existing multiphase DC-DC power converters, multiple power stages each include a complete main circuit, with their output terminals connected to the same load terminal, achieving output current subtraction at the load terminal. Multiphase DC-DC power converters employ an interleaved control method, where multiple power stages are sequentially staggered in their conduction, allowing the switching currents to partially cancel each other out across the input and output capacitors. This effectively reduces input and output current ripple, decreases the size and cost of filter components, and improves the overall system conversion efficiency. Interleaved control also balances the current stress across phases, mitigating the risk of single-phase overload and enhancing system reliability. For different output current requirements, the number of operating phases can be dynamically adjusted to achieve optimal efficiency and load matching.

[0004] However, existing multiphase DC-DC power converters require each power stage to have an independent inductor, leading to an increase in the number of external components, system cost, and board area. While interleaving control can effectively reduce current ripple, it requires sophisticated multiphase clock signal generation and distribution circuitry, increasing controller complexity and cost. Furthermore, phase differences between the drive signals of each phase can cause crosstalk between control loops through shared input and output impedance paths, posing challenges to system stability design. Simultaneously, the interleaved switching of multiple transistors broadens the electromagnetic interference (EMI) noise spectrum, increasing the complexity of EMI filtering design. Moreover, parameter differences between power stages (such as inductance values ​​and transistor characteristics) can lead to uneven current distribution, i.e., current sharing problems, causing localized overheating and severely limiting the improvement of system output capability and reliability. Summary of the Invention

[0005] In view of the above problems, the purpose of this invention is to provide a multiphase DC-DC power converter and its control method, wherein multiple switching modules of the power converter share energy storage elements and are synchronously turned on, so as to reduce circuit cost, suppress interphase crosstalk, and eliminate current sharing error caused by parameter differences of energy storage elements.

[0006] According to one aspect of the present invention, a multiphase DC-DC power converter is provided, comprising: a plurality of switching modules, each of the plurality of switching modules including a first switching transistor and a second switching transistor connected in series, the intermediate node of the first switching transistor and the second switching transistor of the plurality of switching modules being connected to a switching node, through which an energy storage element is charged and discharged; and a control circuit for providing drive signals to the first switching transistor and the second switching transistor of each switching module, wherein the control circuit is configured to synchronously turn on the first switching transistors of the plurality of switching modules, and to synchronously turn on the second switching transistors of the plurality of switching modules after detecting that the first switching transistors of the plurality of switching modules are all turned off.

[0007] Optionally, the control circuit is configured to synchronously turn off the first switching transistor of the plurality of switching modules according to a first current detection signal characterizing the current flowing through the switching node.

[0008] Optionally, the control circuit includes: an error amplifier for generating a compensation signal based on a feedback signal of the DC output voltage; a subtractor for subtracting the compensation signal from a periodic sawtooth wave signal to generate a modulation signal; a comparison module for comparing the modulation signal with the first current detection signal to generate a turn-off signal; and an upper-side control logic module for generating a drive signal for the first switching transistor based on the turn-off signal and a clock signal.

[0009] Optionally, the control circuit is configured to synchronously turn off the first switching transistors of the plurality of switching modules according to the first voltage signal of the switching node.

[0010] Optionally, the control circuit includes: an error amplifier for generating a compensation signal based on a feedback signal of the DC output voltage; a subtractor for subtracting the compensation signal from a periodic sawtooth wave signal to generate a modulation signal; a comparison module for comparing the modulation signal with the first voltage signal to generate a turn-off signal; and an upper transistor control logic module for generating a drive signal for the first switching transistor based on the turn-off signal and a clock signal.

[0011] Optionally, the comparison module includes: a comparator, which is bipolar powered by a startup voltage and the first voltage signal, and the inverting input of the comparator receives the first voltage signal; a current mirror, which converts the first voltage signal into a proportional current signal and mirrors it to the non-inverting input of the comparator, wherein the output of the comparator generates the shutdown signal.

[0012] Optionally, the control circuit is configured to turn off the first switching transistor of the plurality of switching modules respectively based on a second current detection signal used to characterize the current flowing through the first switching transistor and the second switching transistor.

[0013] Optionally, the control circuit includes: an error amplifier for generating a compensation signal based on a feedback signal of the DC output voltage; a subtractor for subtracting the compensation signal from a periodic sawtooth wave signal to generate a modulation signal; multiple comparison modules for comparing the modulation signal with the second current detection signals of the multiple switching modules respectively to generate multiple turn-off signals; and multiple upper-side control logic modules for generating drive signals for the first switching transistors of the multiple switching modules based on the multiple turn-off signals and a clock signal.

[0014] Optionally, the control circuit further includes: an upper-side turn-off judgment module, used to determine whether all the first switching transistors of the plurality of switching modules have been turned off based on the drive signal and / or source-drain voltage of the first switching transistors of the plurality of switching modules; a delay module, used to perform a preset delay to generate a delay signal after the upper-side turn-off judgment module confirms that all the first switching transistors have been turned off; and a lower-side control logic module, used to generate drive signals for the second switching transistors of the plurality of switching modules based on the delay signal and the clock signal.

[0015] Optionally, the multiphase DC-DC power converter is any one of a BUCK-type power circuit, a BOOST-type power circuit, and a BUCK-BOOST-type power circuit.

[0016] Optionally, the energy storage element includes at least one inductor connected between the DC voltage input terminal and the switching node.

[0017] Optionally, the energy storage element includes at least one inductor connected between the DC voltage output terminal and the switching node.

[0018] Optionally, the at least one inductor includes a plurality of discrete inductors connected in parallel.

[0019] According to another aspect of the present invention, a control method for a multiphase DC-DC power converter is provided, the multiphase DC-DC power converter including a plurality of switching modules, each switching module including a first switching transistor and a second switching transistor connected in series, the control method including: in each switching cycle, synchronously turning on the first switching transistors of the plurality of switching modules to charge an energy storage element through a common switching node; after detecting that the first switching transistors of the plurality of switching modules are all turned off, synchronously turning on the second switching transistors of the plurality of switching modules to discharge the energy storage element through a common switching node.

[0020] Optionally, the control method further includes: simultaneously turning off the first switching transistor of the plurality of switching modules according to a first current detection signal characterizing the current flowing through the switching node.

[0021] Optionally, the control method further includes:

[0022] Based on the first voltage signal of the switching node, the first switching transistors of the plurality of switching modules are synchronously turned off.

[0023] Optionally, the control method further includes: turning off the first switching transistors of the plurality of switching modules respectively according to the second current detection signal characterizing the first switching transistor flowing through each switching module.

[0024] Optionally, after detecting that the first switching transistors of the plurality of switching modules are all turned off, the step of synchronously turning on the second switching transistors of the plurality of switching modules includes: determining whether the first switching transistors of the plurality of switching modules have all been turned off based on the drive signal and / or source-drain voltage of the first switching transistors of the plurality of switching modules; and after the first switching transistors of the plurality of switching modules have all been turned off, synchronously turning on the second switching transistors of the plurality of switching modules after a preset delay.

[0025] According to embodiments of the multiphase DC-DC power converter of the present invention, multiple switching modules share an external energy storage element to simplify the number of peripheral components. By enabling any number of switching modules, the drive current requirements of different loads can be adapted. Furthermore, current sharing and overall system efficiency are improved by matching the switching transistor parameters of multiple switching modules, and the output current ripple can be effectively reduced by adopting a synchronous control strategy. Attached Figure Description

[0026] The above and other objects, features and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings.

[0027] Figure 1 A schematic circuit diagram of an existing multiphase DC-DC power converter is shown.

[0028] Figure 2 Show Figure 1 The waveform diagram shown is of the multiphase DC-DC power converter.

[0029] Figure 3 A schematic circuit diagram of a multiphase DC-DC power converter according to a first embodiment of the present invention is shown;

[0030] Figure 4 Show Figure 3 A schematic circuit diagram of the control circuit in the multiphase DC-DC power converter shown.

[0031] Figure 5Show Figure 4 A schematic circuit diagram of the comparison module in the control circuit shown.

[0032] Figure 6 A schematic circuit diagram of a multiphase DC-DC power converter according to a second embodiment of the present invention is shown;

[0033] Figure 7 Show Figure 6 A schematic circuit diagram of the control circuit in the multiphase DC-DC power converter shown.

[0034] Figure 8 Show Figure 7 A schematic circuit diagram of the comparison module in the control circuit shown.

[0035] Figure 9 The diagram shows the operating waveforms of the multiphase DC-DC power converter according to the first and second embodiments of the present invention.

[0036] Figure 10 A schematic circuit diagram of a multiphase DC-DC power converter according to a third embodiment of the present invention is shown;

[0037] Figure 11 Show Figure 10 A schematic circuit diagram of the control circuit in the multiphase DC-DC power converter shown.

[0038] Figure 12 The diagram shows the operating waveforms of a multiphase DC-DC power converter according to the third embodiment. Detailed Implementation

[0039] Various embodiments of the invention will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements are indicated by the same or similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale.

[0040] This invention can be presented in various forms, some of which will be described below.

[0041] In this document, the term "power stage" includes a switching module and energy storage elements connected thereto to achieve power conversion. For example, a switching module includes a first switch and a second switch, which are used to alternately turn on and off under the action of a control signal to charge and discharge the energy storage element, thereby achieving voltage conversion. The term "switching node" refers to the intermediate node in the switching module where multiple switches are connected to the energy storage element. The term "energy storage element" includes inductors and capacitors. Depending on the type of energy storage element, capacitive power converters and inductive power converters can be constructed. Depending on the connection method of the energy storage element, different topology power converters can be constructed.

[0042] The embodiments disclosed herein are applicable to power conversion circuits of various topologies, including but not limited to: any one of BUCK-type power conversion circuits, BOOST-type power conversion circuits, and BUCK-BOOST-type power conversion circuits. The following description primarily uses a BUCK-type power conversion circuit as an example; however, this disclosure is not limited thereto.

[0043] The embodiments disclosed herein are applicable to any number of multiphase power converters, including two-phase, three-phase, and higher power stages. The following description primarily uses a two-phase power conversion circuit as an example; however, this disclosure is not limited thereto.

[0044] Figure 1 A schematic circuit diagram of an existing multiphase DC-DC power converter is shown. The multiphase DC-DC power converter 100 includes a first main circuit and a second main circuit, as well as a first control circuit 10 and a second control circuit 20.

[0045] The first main circuit includes switching transistors Q11 and Q12 connected in series between the DC voltage input terminal and the ground terminal, and an inductor L1 connected between the switching node SW1 between the switching transistors Q11 and Q12 and the output terminal. The first main circuit also includes an output capacitor Co1 connected between the output terminal and the ground terminal to filter out ripple components in the output voltage Vo1. Further, a load resistor RL1 is connected between the DC voltage output terminal and the ground terminal to represent the load in the actual working scenario. Resistors R11 and R12 are connected in series between the DC voltage output terminal and the ground terminal, forming a voltage divider network used to sample the output voltage Vo1 to obtain a voltage feedback signal Vfb1, which is then provided to the first control circuit 10.

[0046] The second main circuit includes switching transistors Q21 and Q22 connected in series between the DC voltage input terminal and the ground terminal, and an inductor L2 connected between the switching node SW2 between the switching transistors Q21 and Q22 and the output terminal. The second main circuit also includes an output capacitor Co2 connected between the output terminal and the ground terminal to filter out ripple components in the output voltage Vo2. A load resistor RL2 is connected between the output terminal and the ground terminal. Resistors R21 and R22 form a voltage divider network to sample the output voltage Vo2 to obtain a voltage feedback signal Vfb2, which is then provided to the second control circuit 20.

[0047] The first control circuit 10 generates a first upper transistor drive signal and a first lower transistor drive signal based on the inductor current detection signal Isen1 and the voltage feedback signal Vfb1 of the first main circuit. These signals are used to adjust the conduction and cutoff of the switching transistors Q11 and Q12, thereby stabilizing the output voltage Vo1.

[0048] Specifically, the first control circuit 10 is used to implement peak current mode control. This control circuit includes a voltage loop, a current loop, a comparison module 102, and a control logic module 103. The voltage loop includes an error amplifier 101, and a compensation resistor Rc1 and a compensation capacitor Cc1 connected in series between the output of the error amplifier 101 and ground, forming a loop compensation network. The non-inverting input of the error amplifier 101 receives a reference voltage Vref1, the inverting input receives a voltage feedback signal Vfb1, and generates a compensation voltage signal Vcomp1 at the output. Preferably, the voltage loop also includes a subtractor 111, used to subtract the compensation voltage signal Vcomp1 from the ramp signal Ramp1 to obtain a modulation signal, thereby improving loop stability and suppressing subharmonic oscillations. The current loop is used to detect the inductor current, generating an inductor current detection signal Isen1 through a sampling device such as a current sampling resistor. The non-inverting input of the comparator module 102 receives the inductor current detection signal Isen1, the inverting input receives the modulation signal, and generates a first turn-off signal OFF1 at the output. The control logic module 103 generates a first upper-side drive signal and a first lower-side drive signal based on the first clock signal CLK_a and the first turn-off signal OFF1 to achieve complementary control of the switching transistors Q11 and Q12.

[0049] The second control circuit 20 generates a second upper transistor drive signal and a second lower transistor drive signal based on the inductor current detection signal Isen2 and the voltage feedback signal Vfb2 of the second main circuit. These signals are used to adjust the conduction and cutoff of the switching transistors Q21 and Q22, thereby stabilizing the output voltage Vo2.

[0050] The second control circuit 20 is used to implement peak current mode control. The internal circuit structure of the second control circuit 20 is the same as that of the first control circuit 10, and will not be described in detail here.

[0051] Figure 1 The two-phase DC-DC power converter 100 shown has two independent output terminals, thus enabling single-channel or dual-channel output modes depending on the number of loads. The first control circuit 10, the second control circuit 20, the switches Q11 and Q12 in the first main circuit, and the switches Q21 and Q22 in the second main circuit of this DC-DC power converter can be integrated into a single chip to form a two-phase DC-DC power converter chip.

[0052] However, based on Figure 1The dual-output architecture shown in the diagram means that the two outputs of this two-phase DC-DC power converter 100 are controlled by independent voltage loops and compensation networks, respectively. Therefore, the two outputs cannot be directly connected in parallel for the same load, as this would lead to loop conflicts and instability. Consequently, this two-phase DC-DC power converter 100 cannot be directly connected in parallel to support high-current applications with a single load.

[0053] To support high-current applications with a single load, the two control circuits of the two-phase DC-DC power converter 100 need to work together. For this purpose, the first control circuit 10 and the second control circuit 20 share the compensation voltage signal Vcomp1 and perform independent slope compensation based on their respective slope signals Ramp1 and Ramp2.

[0054] See Figure 2 The first clock signal CLK_a in the first control circuit 10 and the second clock signal CLK_b in the second control circuit 20 are 180 degrees out of phase. The ramp signals Ramp1 and Ramp2 are also out of phase accordingly to achieve two-phase interleaved operation, thereby achieving the inductor current waveform to be staggered and mutually canceling the output ripple.

[0055] Figure 3 A schematic circuit diagram of a multiphase DC-DC power converter according to a first embodiment of the present invention is shown. The multiphase DC-DC power converter 200 includes a first main circuit and a second main circuit, as well as a control circuit 30.

[0056] The first main circuit includes switching transistors Q11 and Q12 connected in series between the DC voltage input terminal and the ground terminal, forming a first switching module. The second main circuit includes switching transistors Q21 and Q22 connected in series between the DC voltage input terminal and the ground terminal, forming a second switching module. The intermediate node of switching transistors Q11 and Q12 in the first switching module and the intermediate node of switching transistors Q21 and Q22 in the second switching module are connected to the same switching node SW. The first and second main circuits share an inductor L and an output capacitor Co. The inductor L is connected between the switching node SW and the output terminal. The output capacitor Co is connected between the output terminal and the ground terminal to filter out the ripple component in the output voltage Vo.

[0057] Furthermore, the load resistor RL is connected between the DC voltage output terminal and the ground terminal to represent the load in the actual working scenario. Resistors R11 and R12 are connected in series between the DC voltage output terminal and the ground terminal, forming a voltage divider network to sample the output voltage Vo to obtain the voltage feedback signal Vfb, and then provide the voltage feedback signal Vfb to the control circuit 30.

[0058] The control circuit 30 generates an upper transistor drive signal HG based on the inductor current detection signal Isen and the voltage feedback signal Vfb, which is used to drive Q11 and Q21 in the first switching module, and a lower transistor drive signal LG, which is used to drive Q12 and Q22 in the second switching module, so as to realize the two-phase parallel operation.

[0059] Figure 4 Show Figure 3 The diagram shows a schematic circuit of the control circuit in a multiphase DC-DC power converter. In this embodiment, the control circuit 30 is used to implement peak current mode control; however, the invention is not limited thereto.

[0060] The control circuit 30 includes a voltage loop, a current loop, a comparison module 102, an upper transistor control logic module 113, an upper transistor turn-off detection module 201, a delay module 202, and a lower transistor control logic module 213.

[0061] The voltage loop includes an error amplifier 101, and a compensation resistor Rc and a compensation capacitor Cc connected in series between the output of the error amplifier 101 and the ground terminal to form a loop compensation network. The non-inverting input of the error amplifier 101 receives a reference voltage Vref1, the inverting input receives a voltage feedback signal Vfb, and generates a compensation voltage signal Vcomp at the output. Preferably, the voltage loop also includes a subtractor 111, which subtracts the compensation voltage signal Vcomp from the ramp signal Ramp to obtain a modulation signal, thereby improving loop stability and suppressing subharmonic oscillations. The current loop is used to detect the inductor current, and generates an inductor current detection signal Isen through a sampling device such as a current sampling resistor.

[0062] The comparison module 102 receives the inductor current detection signal Isen and the modulation signal Vmod, compares the two, and generates a first turn-off signal OFF1 at the output. The upper MOSFET control logic module 113 generates an upper MOSFET drive signal HG based on the clock signal CLK and the first turn-off signal OFF1.

[0063] See Figure 5 The comparison module 102 includes a comparator 11. The non-inverting input of the comparator 11 receives an inductor current detection signal Isen, the inverting input receives a modulation signal Vmod, and the output provides a first turn-off signal OFF1. For example, Isen = iL × Ri, where iL represents the inductor current and Ri represents the current detection resistor value. For example, Vmod = Vcomp - Ramp, where Vcomp represents the compensation voltage and Ramp represents the ramp signal.

[0064] The upper transistor turn-off detection module 201 determines whether both switching transistors Q11 and Q21 have been turned off based on the drive signals and / or source-drain voltages of switching transistors Q11 in the first switching module and Q21 in the second switching module. For example, the upper transistor turn-off detection module 201 detects the falling edge of the upper transistor drive signal HG to confirm the start time of the turn-off of switching transistors Q11 and Q21. The delay module 202 extends the turn-off start time by a predetermined time to ensure that the second turn-off signal OFF2 is generated after switching transistors Q11 and Q21 are completely turned off. The lower transistor control logic module 213 generates the lower transistor drive signal LG based on the clock signal CLK and the second turn-off signal OFF2.

[0065] In this embodiment, the upper-side control logic module 113 and the lower-side control logic module 213 are, for example, RS flip-flops. The clock signal CLK serves as the set signal for the RS flip-flop, and the first turn-off signal OFF1 and the second turn-off signal OFF2 serve as reset signals, thereby generating the upper-side drive signal HG and the lower-side drive signal LG. Further, using inverters can obtain complementary upper-side drive signals HG and LG. In alternative embodiments, any logic circuit can be used to implement the same function, such as combinational gate circuits or microcontroller units.

[0066] According to the multiphase DC-DC power converter of the first embodiment, multiple switching modules charge and discharge inductor L via a common switching node. Since multiple switching modules share an external energy storage element, the number of external components can be simplified. By enabling any number of switching modules, the drive current requirements of different loads can be adapted. Furthermore, this multiphase DC-DC power converter only requires switching transistor parameter matching, not inductor parameter matching, thereby reducing system design complexity and stringent requirements for component consistency. Current sharing and improved overall system efficiency can be achieved through switching transistor parameter matching of multiple switching modules. In addition, the synchronous control strategy can effectively reduce output current ripple.

[0067] Furthermore, the control circuit 30 in the multiphase DC-DC power converter shares a voltage loop and a current loop, generating a shared upper transistor drive signal HG and a lower transistor drive signal based on the inductor current detection signal and the voltage feedback signal. The control circuit 30 uses the upper transistor drive signal HG to synchronously drive the switch Q11 in the first switching module and the switch Q21 in the second switching module, thereby achieving synchronous conduction. Furthermore, the control circuit 30 uses the lower transistor drive signal LG to synchronously drive the switch Q12 in the first switching module and the switch Q22 in the second switching module, thereby achieving synchronous conduction.

[0068] Furthermore, by precisely setting the delay time of the delay module 202, the desired dead zone can be obtained, ensuring that the switching transistors Q11 in the first switching module and Q21 in the second switching module are both turned off before the switching transistors Q12 in the first switching module and Q22 in the second switching module are turned on. This avoids the punch-through current caused by the simultaneous conduction of the upper and lower transistors, thereby improving the system reliability and conversion efficiency.

[0069] Figure 6 A schematic circuit diagram of a multiphase DC-DC power converter according to a second embodiment of the present invention is shown. The multiphase DC-DC power converter 300 includes a first main circuit, a second main circuit, and a control circuit 40.

[0070] The first main circuit and the second main circuit in the multiphase DC-DC power converter 300 according to the second embodiment have the same circuit structure as those in the first embodiment, and will not be described in detail here.

[0071] The control circuit 40 generates an upper transistor drive signal HG based on the voltage feedback signal Vfb of the switching node voltage Vsw and the output voltage, which is used to drive Q11 and Q21 in the first switching module, and a lower transistor drive signal LG, which is used to drive Q12 and Q22 in the second switching module, so as to realize the two-phase parallel operation.

[0072] Figure 7 Show Figure 6 The diagram shows a schematic circuit of the control circuit in a multiphase DC-DC power converter. In this embodiment, the control circuit 40 is used to implement peak current mode control; however, the invention is not limited thereto.

[0073] The control circuit 30 includes a voltage loop, a current loop, a comparison module 112, an upper transistor control logic module 113, an upper transistor turn-off detection module 201, a delay module 202, and a lower transistor control logic module 213.

[0074] According to the second embodiment of the multiphase DC-DC power converter 300, the voltage loop and current loop in the control circuit 30 are the same as those in the first embodiment, and will not be described in detail here.

[0075] Unlike the first embodiment, the comparison module 112 in the control circuit 30 receives the switching node voltage Vsw and the modulation signal Vmod, compares the two, and generates a first turn-off signal OFF1 at the output. The upper-side control logic module 113 generates an upper-side drive signal HG based on the clock signal CLK and the first turn-off signal OFF1.

[0076] See Figure 8The comparator module 112 includes a comparator 11, transistors Q1 and Q2, and a resistor R1. Transistors Q1 and Q2 are connected in a current mirror structure, with their gates connected to each other and to the drain of transistor Q1, and their sources grounded. The drain of transistor Q1 receives the modulated current signal Imod = Vmod / Rmod corresponding to the modulated signal Vmod, where Rmod represents the equivalent resistance value. For example, Vmod = Vcomp - Ramp, where Vcomp represents the compensation voltage and Ramp represents the ramp signal. Resistor R1 is connected between the DC voltage input terminal and the drain of transistor Q2. At the midpoint between transistor Q2 and resistor R1, an upper-side reference voltage HS_ref corresponding to the modulated signal Vmod is generated. If the mirror ratio of the current mirror structure is 1:1, then the upper-side reference voltage HS_ref = Vin - Imod * R1 = Vin - (Vcomp - Ramp) * R1 / Rmod.

[0077] The non-inverting input of comparator 11 receives the reference voltage HS_ref, the inverting input receives the switching node voltage Vsw, and the output provides the first turn-off signal OFF1. Furthermore, comparator 11 employs a bootstrap power supply. The bipolar supply voltages of comparator 11 are the startup voltage Vboot and the switching node voltage Vsw. When the switching node voltage Vsw changes, the supply voltage of comparator 11 dynamically adjusts accordingly, thereby ensuring that its input common-mode range remains within the effective operating range.

[0078] The upper transistor turn-off detection module 201 determines whether both switching transistors Q11 and Q21 have been turned off based on the drive signals and / or source-drain voltages of switching transistors Q11 in the first switching module and Q21 in the second switching module. For example, the upper transistor turn-off detection module 201 detects the falling edge of the upper transistor drive signal HG to confirm the start time of the turn-off of switching transistors Q11 and Q21. The delay module 202 extends the turn-off start time by a predetermined time to ensure that the second turn-off signal OFF2 is generated after switching transistors Q11 and Q21 are completely turned off. The lower transistor control logic module 213 generates the lower transistor drive signal LG based on the clock signal CLK and the second turn-off signal OFF2.

[0079] According to the second embodiment of the multiphase DC-DC power converter 300, the circuit implementation of the upper-side control logic module 113 and the lower-side control logic module 213 in the control circuit 40 is the same as that in the first embodiment, and will not be described in detail here.

[0080] According to the multiphase DC-DC power converter of the second embodiment, multiple switching modules charge and discharge inductor L via a common switching node. Since multiple switching modules share an external energy storage element, the number of external components can be simplified. By enabling any number of switching modules, the drive current requirements of different loads can be adapted. Furthermore, this multiphase DC-DC power converter only requires switching transistor parameter matching, not inductor parameter matching, thereby reducing system design complexity and stringent requirements for component consistency. Current sharing and improved overall system efficiency can be achieved through switching transistor parameter matching of multiple switching modules. In addition, the synchronous control strategy can effectively reduce output current ripple.

[0081] Furthermore, the control circuit 40 in the multiphase DC-DC power converter shares a voltage loop and a current loop, generating a shared upper transistor drive signal HG and a lower transistor drive signal LG based on the inductor current detection signal and the voltage feedback signal. The control circuit 40 uses the upper transistor drive signal HG to synchronously drive the switch Q11 in the first switching module and the switch Q21 in the second switching module, thereby achieving synchronous conduction. The control circuit 30 uses the lower transistor drive signal LG to synchronously drive the switch Q12 in the first switching module and the switch Q22 in the second switching module, thereby achieving synchronous conduction.

[0082] Furthermore, the comparator in the control circuit 40 compares the switching node voltage Vsw with the shift signal of the compensation voltage signal Vcomp to obtain the first turn-off signal OFF1. Since the switching node voltage Vsw directly reflects the turn-off end time of the switching transistor Q12 in the first switching module and the switching transistor Q22 in the second switching module, the desired dead time can be set more accurately based on the falling edge of the upper transistor drive signal HG. This ensures that the switching transistors Q11 in the first switching module and Q21 in the second switching module are both turned off before the switching transistors Q12 in the first switching module and Q22 in the second switching module are turned on, thereby avoiding the shoot-through current caused by the simultaneous conduction of the upper and lower transistors and improving system reliability and conversion efficiency.

[0083] Furthermore, in this embodiment, the comparator in the control circuit 40 adopts a bootstrap power supply method. During the power-down period of the multiphase DC-DC power converter, even if the DC input voltage Vin decreases to zero, the comparator powered by the startup voltage Vboot can still work normally, thereby ensuring that the switching transistor Q11 in the first switching module and the switching transistor Q21 in the second switching module are turned off normally.

[0084] Figure 9 The diagram shows the operating waveforms of a multiphase DC-DC power converter according to the first and second embodiments of the present invention.

[0085] As shown in the figure, multiple switching modules in a multiphase DC-DC power converter are synchronously controlled based on a common clock signal CLK. The time interval between consecutive rising edges of the clock signal CLK corresponds to one switching cycle of all the switching transistors in the multiple switching modules.

[0086] Taking one switching cycle as an example, the working principle of a multiphase DC-DC power converter will be further explained below.

[0087] At time t0, the first rising edge of the clock signal CLK arrives, and the multiphase DC-DC power converter begins a new switching cycle. The upper transistor drive signal HG is set high due to the rising edge of the clock signal CLK, and the lower transistor drive signal LG is set low due to the rising edge of the clock signal CLK. At this time, switching transistors Q11 in the first switching module and Q21 in the second switching module are synchronously turned on, and switching transistors Q12 in the first switching module and Q22 in the second switching module are synchronously turned off.

[0088] At this point, the DC input voltage Vin charges the inductor L through the common switching node SW, causing the inductor current iL to rise linearly. The inductor current iL is the sum of the shunt current i1 from the first switching module and the shunt current i2 from the second switching module. By matching the switching parameters of the first and second switching modules, for example, by integrating MOSFETs with the same on-resistance on the same chip, the same shunt ratio can be obtained, thereby achieving current sharing control. The switching node voltage Vsw is approximately equal to the DC input voltage Vin minus the on-state voltage drops of switching transistors Q11 and Q21, respectively.

[0089] At time t1, the inductor current iL reaches its peak value determined by the compensation voltage signal Vcomp. The comparator compares the inductor current detection signal with the compensation voltage signal Vcomp, causing the first turn-off signal OFF1 to flip from an invalid state to an active state. The upper MOSFET control logic module sets the upper MOSFET drive signal HG to a low level based on the active state of the first turn-off signal OFF1.

[0090] At this point, the turn-off start time of switch Q11 in the first switching module and switch Q21 in the second switching module corresponds to the falling edge of the upper transistor drive signal HG. However, due to the difference in physical parameters between switches Q11 and Q21, their switching speeds differ, making it difficult for them to turn off simultaneously. For example, switch Q11 may turn off first due to its smaller parasitic parameters, while switch Q21 may turn off slightly later due to its larger parasitic parameters. During the brief period when switch Q11 is off and switch Q21 is still conducting, the inductor current iL flows entirely through switch Q21, causing a current imbalance. The switching node voltage Vsw is still approximately equal to the DC input voltage Vin minus the on-state voltage drops of switches Q11 and Q21, respectively.

[0091] At time t2, the switch Q21 in the second switching module completes its turn-off action. The inductor current iL is still a forward current, and the switching node SW is grounded through the body diodes of the switches Q12 and Q22, rapidly pulling down from a high level to near ground potential, approximately equal to the forward voltage drop of the body diodes of the switches Q12 and Q22.

[0092] At time t3, after determining that both switch Q11 in the first switching module and switch Q21 in the second switching module are turned off, after a predetermined dead time, the lower transistor drive signal LG flips from low to high. Switch Q12 in the first switching module and switch Q22 in the second switching module are synchronously turned on, while switch Q11 in the first switching module and switch Q21 in the second switching module remain in the off state.

[0093] At this time, the inductor L discharges to ground through the common switching node SW, causing the inductor current iL to decrease linearly.

[0094] At time t4, the second rising edge of the clock signal CLK arrives, and the multiphase DC-DC power converter begins the next switching cycle, thus ending the current switching cycle.

[0095] Figure 10 A schematic circuit diagram of a multiphase DC-DC power converter according to a third embodiment of the present invention is shown. The multiphase DC-DC power converter 400 includes a first main circuit, a second main circuit, and a control circuit 50.

[0096] The first main circuit and the second main circuit in the multiphase DC-DC power converter 400 according to the third embodiment have the same circuit structure as those in the first embodiment, and will not be described in detail here.

[0097] The control circuit 50 generates a first upper transistor drive signal HG1 and a second upper transistor drive signal HG2 based on the current detection signal Isen1 of the first switching module, the current detection signal Isen2 of the second switching module, and the voltage feedback signal Vfb of the output voltage. These signals are used to drive the switching transistors Q11 and Q21 in the first switching module, respectively. The control circuit 50 also generates a lower transistor drive signal LG to drive the switching transistors Q12 and Q22 in the first switching module.

[0098] Figure 11 Show Figure 10 The diagram shows a schematic circuit of the control circuit in a multiphase DC-DC power converter. In this embodiment, the control circuit 50 is used to implement peak current mode control; however, the invention is not limited thereto.

[0099] The control circuit 50 includes a voltage loop, a current loop, comparison modules 102a and 102b, upper transistor control logic modules 113a and 113b, upper transistor turn-off detection module 201, delay module 202, and lower transistor control logic module 213.

[0100] According to the multiphase DC-DC power converter 400 of the third embodiment, the voltage loop in the control circuit 40 is the same as that in the first embodiment, and will not be described in detail here. The current loop in the control circuit 50 samples the inductor current iL in the shunt i1 of the first switching module and the shunt i2 of the second switching module to obtain current detection signals Isen1 and Isen2.

[0101] The comparison module 102a receives the current detection signal Isen1 and the modulation signal Vmod, compares the two, and generates a first turn-off signal OFF1a at the output. The upper-side control logic module 113a generates a first upper-side drive signal HG1 based on the clock signal CLK and the first turn-off signal OFF1a.

[0102] The comparison module 102b receives the current detection signal Isen2 and the modulation signal Vmod, compares the two, and generates a first turn-off signal OFF1b at the output. The upper MOSFET control logic module 113b generates a second upper MOSFET drive signal HG2 based on the clock signal CLK and the first turn-off signal OFF1b.

[0103] In the multiphase DC-DC power converter 400 according to the third embodiment, the circuit structures of the comparison modules 102a and 102b are the same as those in the first embodiment, and will not be described in detail here.

[0104] The upper transistor turn-off detection module 201 determines whether both switching transistors Q11 and Q21 have been turned off based on the drive signals and / or source-drain voltages of switching transistors Q11 in the first switching module and Q21 in the second switching module. For example, the upper transistor turn-off detection module 201 detects the falling edges of the upper transistor drive signals HG1 and HG2 to confirm the turn-off start time of switching transistors Q11 and Q21. The delay module 202 extends the turn-off start time by a predetermined time to ensure that the second turn-off signal OFF2 is generated after switching transistors Q11 and Q21 are completely turned off. The lower transistor control logic module 213 generates the lower transistor drive signal LG based on the clock signal CLK and the second turn-off signal OFF2.

[0105] According to the third embodiment of the multiphase DC-DC power converter 400, the circuit implementation of the upper-side control logic modules 113a and 113b and the lower-side control logic module 213 in the control circuit 50 is the same as that in the first embodiment, and will not be described in detail here.

[0106] According to the third embodiment of the multiphase DC-DC power converter, compared with the first and second embodiments, the control circuit 50 shares a voltage loop but also has its own current loop. The control circuit 50 generates upper transistor drive signals HG1 and HG2 for each phase based on the current detection signal and voltage feedback signal of each phase, and generates a shared lower transistor drive signal LG for all phases. The control circuit 50 can not only achieve synchronous turn-on of the switching transistor Q11 in the first switching module and the switching transistor Q21 in the second switching module, and synchronous turn-on of the switching transistors Q12 in the first switching module and Q22 in the second switching module, but also achieve independent turn-off control of the switching transistors Q11 in the first switching module and Q21 in the second switching module. Even if the switching transistor parameters of the first and second switching modules differ, the turn-off time of the upper transistors in each phase switching module can still be accurately controlled when independent peak current control is used for all upper transistors in the multiphase switching modules, thereby improving loop stability and circuit efficiency. Therefore, adopting independent peak current control can further reduce system design complexity and stringent requirements for component consistency.

[0107] Figure 12 The diagram shows the operating waveforms of a multiphase DC-DC power converter according to the third embodiment.

[0108] As shown in the figure, multiple switching modules in a multiphase DC-DC power converter are synchronously controlled based on a common clock signal CLK. The time interval between consecutive rising edges of the clock signal CLK corresponds to one switching cycle of all the switching transistors in the multiple switching modules.

[0109] Taking one switching cycle as an example, the working principle of a multiphase DC-DC power converter will be further explained below.

[0110] At time t0, the first rising edge of the clock signal CLK arrives, and the multiphase DC-DC power converter begins a new switching cycle. The first upper transistor drive signal HG1 and the second upper transistor drive signal HG2 are set to high level due to the rising edge of the clock signal CLK, while the lower transistor drive signal LG is set to low level due to the rising edge of the clock signal CLK. At this time, the switching transistors Q11 and Q21 in the first and second switching modules are synchronously turned on, and the switching transistors Q12 and Q22 in the first and second switching modules are synchronously turned off.

[0111] At this point, the DC input voltage Vin charges the inductor L via the common switching node SW, causing the inductor current iL to rise linearly. The inductor current iL is the superposition of the shunt current i1 from the first switching module and the shunt current i2 from the second switching module. In this embodiment, the switching transistor parameters of the first and second switching modules differ; for example, the on-resistance of the transistor in the first switching module is less than that in the second switching module, making the shunt current i1 of the first switching module greater than that of the shunt current i2 of the second switching module. The junction voltage Vsw is approximately equal to the DC input voltage Vin minus the on-state voltage drops of switching transistors Q11 and Q21, respectively.

[0112] At time t1, the shunt current i1 of the first switching module reaches its peak value determined by the compensation voltage signal Vcomp. The comparator compares the current detection signal with the compensation voltage signal Vcomp, causing the first turn-off signal OFF1a to flip from an invalid state to an active state. The upper transistor control logic module sets the first upper transistor drive signal HG1 to a low level based on the active state of the first turn-off signal OFF1a. The turn-off start time of the switching transistor Q11 in the first switching module is the falling edge of the first upper transistor drive signal HG1.

[0113] At this time, the shunt current i2 of the second switching module has not yet reached the peak value determined by the compensation voltage signal Vcomp. The upper transistor control logic module keeps the second upper transistor drive signal HG2 at a high level according to the valid state of the first turn-off signal OFF1b.

[0114] During the brief period when switch Q11 is off and switch Q21 is still on, the inductor current iL flows entirely through switch Q21, causing a current imbalance. The switching node voltage Vsw is still approximately equal to the DC input voltage Vin minus the on-state voltage drops of switches Q11 and Q21, respectively.

[0115] At time t2, the shunt current i2 of the second switching module reaches its peak value determined by the compensation voltage signal Vcomp. The comparator compares the current detection signal with the compensation voltage signal Vcomp, causing the first turn-off signal OFF1b to flip from an invalid state to an active state. The upper transistor control logic module sets the second upper transistor drive signal HG2 to a low level based on the active state of the first turn-off signal OFF1b. The turn-off start time of the switching transistor Q21 in the second switching module is the falling edge of the second upper transistor drive signal HG2.

[0116] After time t2, after both the switching transistor Q11 in the first switching module and the switching transistor Q21 in the second switching module are turned off, the inductor current iL is still a forward current. The switching node SW is grounded through the body diodes of the switching transistors Q12 and Q22, and is quickly pulled down from a high level to near ground potential, which is approximately equal to the forward voltage drop of the body diodes of the switching transistors Q12 and Q22.

[0117] At time t3, after determining that both switch Q11 in the first switching module and switch Q21 in the second switching module are turned off, after a predetermined dead time, the lower transistor drive signal LG flips from low to high. Switch Q12 in the first switching module and switch Q22 in the second switching module are synchronously turned on, while switch Q11 in the first switching module and switch Q21 in the second switching module remain in the off state.

[0118] At this time, the inductor L discharges to ground through the common switching node SW, causing the inductor current iL to decrease linearly.

[0119] At time t4, the second rising edge of the clock signal CLK arrives, and the multiphase DC-DC power converter begins the next switching cycle, thus ending the current switching cycle.

[0120] According to an embodiment of the present invention, a control method for a multiphase DC-DC power converter is also disclosed. The multiphase DC-DC power converter includes a plurality of switching modules, each switching module including a first switching transistor and a second switching transistor connected in series.

[0121] The control method includes: in each switching cycle, synchronously turning on the first switching transistors of the plurality of switching modules to charge the energy storage element through a common switching node; after detecting that the first switching transistors of the plurality of switching modules are all turned off, synchronously turning on the second switching transistors of the plurality of switching modules to discharge the energy storage element through a common switching node.

[0122] Preferably, the control method further includes: simultaneously turning off the first switching transistor of the plurality of switching modules according to a first current detection signal characterizing the current flowing through the switching node.

[0123] Preferably, the control method further includes: synchronously turning off the first switching transistors of the plurality of switching modules according to the first voltage signal of the switching node.

[0124] Preferably, the control method further includes: turning off the first switching transistors of the plurality of switching modules respectively according to the second current detection signal characterizing the first switching transistor flowing through each switching module.

[0125] Preferably, the step of synchronously turning on the second switching transistors of the plurality of switching modules after detecting that the first switching transistors of the plurality of switching modules are all turned off includes: determining whether the first switching transistors of the plurality of switching modules have all been turned off based on the drive signal and / or source-drain voltage of the first switching transistors of the plurality of switching modules; and synchronously turning on the second switching transistors of the plurality of switching modules after a preset delay after the first switching transistors of the plurality of switching modules have all been turned off.

[0126] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0127] As described above, these embodiments of the present invention do not exhaustively cover all details, nor do they limit the invention to the specific embodiments described. Clearly, many modifications and variations can be made based on the above description. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to effectively utilize the invention and its modifications. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A multiphase DC-DC power converter, comprising: Multiple switching modules, each of which includes a first switching transistor and a second switching transistor connected in series, and the intermediate nodes of the first and second switching transistors of the multiple switching modules are connected to a switching node, through which the energy storage element is charged and discharged. as well as The control circuit is used to provide drive signals to the first and second switching transistors of each switching module. The control circuit is configured to synchronously turn on the first switching transistors of the plurality of switching modules, and to synchronously turn on the second switching transistors of the plurality of switching modules after detecting that the first switching transistors of the plurality of switching modules are all turned off.

2. The multiphase DC-DC power converter according to claim 1, wherein, The control circuit is configured to synchronously turn off the first switching transistor of the plurality of switching modules according to a first current detection signal used to characterize the current flowing through the switching node.

3. The multiphase DC-DC power converter according to claim 2, wherein, The control circuit includes: An error amplifier is used to generate a compensation signal based on the feedback signal of the DC output voltage; A subtractor is used to subtract the compensation signal from the periodic sawtooth wave signal to generate a modulation signal; A comparison module is configured to compare the modulated signal with the first current detection signal to generate a turn-off signal; and The upper-side control logic module is used to generate a drive signal for the first switching transistor based on the turn-off signal and the clock signal.

4. The multiphase DC-DC power converter according to claim 1, wherein, The control circuit is configured to synchronously turn off the first switching transistor of the plurality of switching modules according to the first voltage signal of the switching node.

5. The multiphase DC-DC power converter according to claim 4, wherein, The control circuit includes: An error amplifier is used to generate a compensation signal based on the feedback signal of the DC output voltage; A subtractor is used to subtract the compensation signal from the periodic sawtooth wave signal to generate a modulation signal; A comparison module is configured to compare the modulated signal with the first voltage signal to generate a turn-off signal; and The upper-side control logic module is used to generate a drive signal for the first switching transistor based on the turn-off signal and the clock signal.

6. The multiphase DC-DC power converter according to claim 5, wherein, The comparison module includes: The comparator is bipolar powered by a startup voltage and the first voltage signal, and the inverting input of the comparator receives the first voltage signal. A current mirror converts the first voltage signal into a proportional current signal and mirrors it to the non-inverting input of the comparator. The output of the comparator generates the shutdown signal.

7. The multiphase DC-DC power converter according to claim 1, wherein, The control circuit is configured to turn off the first switching transistor of the plurality of switching modules respectively based on a second current detection signal used to characterize the current flowing through the first switching transistor and the second switching transistor.

8. The multiphase DC-DC power converter according to claim 6, wherein, The control circuit includes: An error amplifier is used to generate a compensation signal based on the feedback signal of the DC output voltage; A subtractor is used to subtract the compensation signal from the periodic sawtooth wave signal to generate a modulation signal; Multiple comparison modules are used to compare the modulation signal with the second current detection signals of the multiple switching modules respectively, so as to generate multiple turn-off signals; and Multiple upper-side control logic modules are used to generate drive signals for the first switching transistors of the multiple switching modules according to the multiple turn-off signals and clock signals.

9. The multiphase DC-DC power converter according to any one of claims 1 to 8, wherein, The control circuit also includes: The upper switch turn-off determination module is used to determine whether the first switch of the multiple switching modules has been turned off based on the drive signal and / or source-drain voltage of the first switch of the multiple switching modules. The delay module is used to generate a delay signal by performing a preset delay after the upper transistor turn-off determination module confirms that all first switching transistors have been turned off; and The lower-level control logic module is used to generate drive signals for the second switching transistors of the plurality of switching modules based on the delay signal and the clock signal.

10. The multiphase DC-DC power converter according to claim 1, wherein, The multiphase DC-DC power converter can be any one of the following: BUCK type power circuit, BOOST type power circuit, and BUCK-BOOST type power circuit.

11. The multiphase DC-DC power converter according to claim 10, wherein, The energy storage element includes at least one inductor connected between the DC voltage input terminal and the switching node.

12. The multiphase DC-DC power converter according to claim 10, wherein, The energy storage element includes at least one inductor connected between the DC voltage output terminal and the switching node.

13. The multiphase DC-DC power converter according to claim 11 or 12, wherein, The at least one inductor includes a plurality of discrete inductors connected in parallel.

14. A control method for a multiphase DC-DC power converter, the multiphase DC-DC power converter comprising a plurality of switching modules, each switching module comprising a first switching transistor and a second switching transistor connected in series, the control method comprising: In each switching cycle, The first switching transistors of the multiple switching modules are simultaneously turned on, and the energy storage element is charged through a common switching node; After detecting that the first switching transistors of the plurality of switching modules are all turned off, the second switching transistors of the plurality of switching modules are simultaneously turned on, and the energy storage element is discharged through a common switching node.

15. The control method according to claim 14, further comprising: Based on a first current detection signal characterizing the current flowing through the switching node, the first switching transistors of the plurality of switching modules are simultaneously turned off.

16. The control method according to claim 14, further comprising: Based on the first voltage signal of the switching node, the first switching transistors of the plurality of switching modules are synchronously turned off.

17. The control method according to claim 14, further comprising: Based on the second current detection signal characterizing the first switching transistor of each switching module, the first switching transistors of the plurality of switching modules are turned off respectively.

18. The control method according to any one of claims 14 to 17, wherein, After detecting that the first switching transistors of the plurality of switching modules are all turned off, the step of simultaneously turning on the second switching transistors of the plurality of switching modules includes: Based on the drive signal and / or source-drain voltage of the first switching transistor of the plurality of switching modules, determine whether the first switching transistor of the plurality of switching modules has been turned off. After the first switches of the multiple switching modules have all been turned off, the second switches of the multiple switching modules are synchronously turned on after a preset delay.

Images