Circuit for improving load transient response speed of LLC converter
By introducing control modules and adjustment modules into the LLC converter, the phase trigger signal switching capacitance and inductance state is enhanced by transient response, the problem of slow transient response speed of the LLC converter is solved, and fast load response is achieved, suitable for application scenarios with large conversion ratios and large currents.
Patent Information
- Application Number
- CN202510546776.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-28
- Publication Date
- 2025-07-25
AI Technical Summary
In the case of high load current and fast dynamic response, the transient response speed of LLC converters is slower, making it difficult to meet the performance requirements of data centers and 5G communication base stations.
By introducing control modules, adjustment modules and converter modules, the charge and discharge states of the capacitors and inductors are switched with transient responses to enhance the charge and discharge states of the capacitors and inductors, instantaneously increase the target voltage, and provide transient current to reduce the voltage drop speed and amplitude of the output load.
While maintaining high efficiency, the load transient response speed of LLC converters is significantly improved, and is suitable for application scenarios with large conversion ratios and high currents.
Smart Images
Figure CN120377656A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the technical field of topology design, and more particularly, to a circuit for improving the load transient response speed of an LLC converter and a control method therefor. Background Art
[0002] DC-DC converters with a large conversion ratio are widely used in application scenarios such as data centers and 5G communication base stations. With the rapid development of artificial intelligence, multi-core CPUs and GPUs in data centers and 5G communication base stations also have the characteristics of large load currents and fast dynamic responses, which requires DC-DC converters with a large conversion ratio to have more excellent performance.
[0003] In the process of implementing the concept of the present disclosure, the inventors found that the LLC converter (inductor-inductor-capacitor resonant converter) in the related art has at least the technical problem of a relatively slow transient response speed. Summary of the Invention
[0004] In view of this, the present disclosure provides a circuit for improving the load transient response speed of an LLC converter and a control method therefor.
[0005] One aspect of the present disclosure provides a converter circuit for improving the load transient response speed of an LLC converter, including:
[0006] A control module, including a transient control unit, wherein the transient control unit generates a transient response enhanced phase trigger signal in response to a transient jump in the output load;
[0007] An adjustment module, including a first capacitor and a first inductor, the adjustment module is configured to switch the charge / discharge state of the first capacitor and the charge / demagnetization state of the first inductor according to the transient response enhanced phase trigger signal, and instantaneously increase the target voltage input to the converter module;
[0008] A converter module, in response to receiving the transient response enhanced phase trigger signal, provides a transient current for the output load according to the target voltage to reduce the voltage drop speed and amplitude of the output load.
[0009] According to an embodiment of the present disclosure, the control module further includes: a steady-state control unit, which generates a steady-state control signal in response to no transient jump in the output load; wherein the adjustment module is further configured to adjust the charge / discharge duration of the first capacitor and the charge / demagnetization duration of the first inductor according to the steady-state control signal, so as to use the first capacitor to provide the target voltage for the converter module.
[0010] According to an embodiment of the present disclosure, the regulation module further includes a first power switch and a second power switch; a first end of the first power switch is connected to an input end of the regulation module, a second end of the first power switch is connected to a first end of a first capacitor, and a first node is included between the first end of the first capacitor and the second end of the first power switch. The first node is connected to the converter module, a second end of the first capacitor is connected to a first end of a first inductor, and a second node is included between the second end of the first capacitor and the first end of the first inductor. The second node is connected to a first end of the second power switch, and a second end of the second power switch is grounded.
[0011] According to an embodiment of the present disclosure, the converter module includes a transformer. A primary side of the transformer includes a first primary switch, a second primary switch, a resonant inductor, and a resonant capacitor. A secondary side of the transformer includes a first secondary switch and a second secondary switch. A first end of the first primary switch is connected to the regulation module, a second end of the first primary switch is connected to the second primary switch, a third node is included between the first primary switch and the second primary switch, and the third node is connected to a series unit including the resonant inductor and the resonant capacitor.
[0012] According to an embodiment of the present disclosure, the control module is further configured to: in response to a transient jump in the output load, adjust the duty ratio of each of a plurality of phases within a single operating cycle to obtain a transient duty ratio; in response to no transient jump in the output load, adjust the duty ratio of each of a plurality of phases within a single operating cycle to obtain a steady-state duty ratio.
[0013] According to an embodiment of the present disclosure, the plurality of phases include a transient response enhancement phase. During the transient response enhancement phase, the second primary switch, the second power switch, and the first secondary switch are turned off, the first primary switch, the first power switch, and the second secondary switch are turned on, and the power supply voltage is used as the target voltage.
[0014] According to an embodiment of the present disclosure, the plurality of phases further include a first phase, a second phase, and a third phase; during the first phase, the second power switch, the first primary switch, and the second secondary switch are turned off, the first power switch, the second primary switch, and the first secondary switch are turned on, the first inductor is magnetized, and the first capacitor is charged; during the second phase, the first power switch, the first primary switch, and the second secondary switch are turned off, the second power switch, the second primary switch, and the first secondary switch are turned on, and the first inductor is demagnetized; during the third phase, the first power switch, the second primary switch, and the first secondary switch are turned off, the second power switch, the first primary switch, and the second secondary switch are turned on, the first inductor is demagnetized, and the first capacitor is discharged.
[0015] According to an embodiment of the present disclosure, the control module is further configured to: in response to a transient jump in the output load, adjust the duty cycle of the first phase to a preset threshold and set the second phase to 0; in response to no transient jump in the output load, set the transient response enhancement phase to 0 and adjust the duty cycle of the third phase to a preset threshold.
[0016] According to an embodiment of the present disclosure, the preset threshold is 0.5.
[0017] According to an embodiment of the present disclosure, the second power switch, the first primary switch, the second primary switch, the first secondary switch, and the second secondary switch all operate in a soft-switching mode, and the second power switch, the first primary switch, and the second primary switch are in a zero-voltage switching mode, while the first secondary switch and the second secondary switch are in a zero-current switching mode.
[0018] Another aspect of the present disclosure provides a control method for improving the load transient response speed of an LLC converter, including: in response to a transient jump in the output load, generating a transient response enhancement phase trigger signal; according to the transient response enhancement phase trigger signal, switching the charge / discharge state of the first capacitor and the charge / demagnetization state of the first inductor to increase the target voltage; providing a transient current for the output load according to the target voltage to reduce the voltage drop speed and amplitude of the output load.
[0019] According to an embodiment of the present disclosure, the control module detects the transient jump by the change trend of the current or voltage of the output load and synchronously generates a transient response enhancement phase trigger signal. The adjustment module switches the charge / discharge state of the first capacitor and the charge / demagnetization state of the first inductor according to the transient response enhancement phase trigger signal, instantaneously increasing the target voltage input to the converter module, so that the converter module receives the transient response enhancement phase trigger signal and provides a transient current for the output load according to the target voltage to reduce the voltage drop speed and amplitude of the output load. Therefore, for application scenarios with a large conversion ratio and large current, while achieving high-efficiency conversion of the LLC converter, fast transient response can also be achieved. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Through the following description of the embodiments of the present disclosure with reference to the drawings, the above and other objects, features, and advantages of the present disclosure will become clearer. In the drawings:
[0021] Figure 1 Schematically shows a structural diagram of a converter circuit for improving the load transient response speed according to an embodiment of the present disclosure.
[0022] Figure 2A Schematically shows a schematic diagram of an LLC converter circuit in the related art.
[0023] Figure 2B Schematically showsFigure 2A The curve of the normalized voltage gain of the shown circuit varying with the switching frequency.
[0024] Figure 2C Schematically shows Figure 2A The waveform diagram of the shown circuit under the condition of a transient jump in the load.
[0025] Figure 3 Schematically shows the circuit diagram for improving the load transient response speed of an LLC converter according to an embodiment of the present disclosure.
[0026] Figure 4 Schematically shows Figure 3 The equivalent circuit diagram of the shown circuit in the transient response enhancement phase.
[0027] Figure 5 Schematically shows Figure 3 The equivalent circuit diagram of the shown circuit in the first phase.
[0028] Figure 6 Schematically shows Figure 3 The equivalent circuit diagram of the shown circuit in the second phase.
[0029] Figure 7 Schematically shows Figure 3 The equivalent circuit diagram of the shown circuit in the third phase.
[0030] Figure 8A Schematically shows Figure 3 The waveform diagram of the shown circuit at steady state.
[0031] Figure 8B Schematically shows Figure 3 The circuit flow diagram of the shown circuit at steady state.
[0032] Figure 9A Schematically shows Figure 3 The waveform diagram of the shown circuit during transient response.
[0033] Figure 9B Schematically shows Figure 3 The circuit flow diagram of the shown circuit during transient response. Detailed implementation manners
[0034] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the following detailed description, for the sake of explanation, numerous specific details are set forth in order to provide a comprehensive understanding of the embodiments of the present disclosure. However, obviously, one or more embodiments may be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concepts of the present disclosure.
[0035] The terms used herein are merely for describing specific embodiments and are not intended to limit the present disclosure. The terms “comprising,” “including,” etc. used herein indicate the presence of the described features, steps, operations, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.
[0036] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those of ordinary skill in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.
[0037] In cases where expressions similar to “at least one of A, B, and C, etc.” are used, generally, it should be interpreted according to the meaning commonly understood by those of ordinary skill in the art (for example, “a system having at least one of A, B, and C” should include, but not be limited to, a system having only A, only B, only C, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).
[0038] In the process of implementing the inventive concept of the present disclosure, the inventors found that:
[0039] Taking the power supply scenario with a large conversion ratio of 48V input and 1V output as an example, in a traditional Buck (step-down) DC-DC converter, the on-time of the upper switch is only 1 / 48 of the switching period. Such an extremely short on-time poses certain challenges to the design of the control and drive circuits. At the same time, since high-voltage devices with a withstand voltage of 48V are required for all power switches, the parasitic parameters of the high-voltage devices are relatively large, which will introduce relatively large losses, thus affecting the system conversion efficiency. In addition, in order to reduce the AC loss of the inductor, an inductor with a large inductance value needs to be used, but the magnetization speed of the inductor with a large inductance value also limits the rising speed of the inductor current during transient response, thereby affecting the transient response speed of the converter.
[0040] In view of this, embodiments of the present disclosure provide a circuit for improving the load transient response speed of an LLC converter, including: a control module including a transient control unit, wherein the transient control unit generates a transient response enhanced phase trigger signal in response to a transient jump in the output load; an adjustment module including a first capacitor and a first inductor, and the adjustment module is configured to switch the charge / discharge state of the first capacitor and the charge / demagnetization state of the first inductor according to the transient response enhanced phase trigger signal to instantaneously increase the target voltage input to the converter module; and a converter module that, in response to receiving the transient response enhanced phase trigger signal, provides a transient current to the output load according to the target voltage to reduce the voltage drop speed and amplitude of the output load.
[0041] Figure 1 Schematically shows a schematic diagram of the circuit structure for improving the load transient response speed of an LLC converter according to an embodiment of the present disclosure.
[0042] As Figure 1 shown, the circuit includes a control module 110, an adjustment module 120, and a converter module 130. Among them, the control module 110 includes a transient control unit 111 that responds to a transient jump in the output load 130'. The adjustment module 120 includes a first capacitor C F and a first inductor L. The adjustment module 120 controls the on / off state of the circuit according to the transient response enhanced phase trigger signal X1, and switches the charge / discharge state of the first capacitor C F and the charge / demagnetization state of the first inductor L to instantaneously increase the magnitude of the target voltage V1 input to the converter module. While receiving the transient response enhanced phase trigger signal X1, the converter module 130 provides a transient current to the output load according to the target voltage V1 so that the voltage drop speed of the output load V O meets a predetermined threshold to avoid the rapid drop of V O .
[0043] According to an embodiment of the present disclosure, the control module 110 monitors the current or voltage fluctuation of the output load 130' in real time. When it detects a step change in the load (such as a sudden increase or decrease), the transient control unit 111 immediately generates a transient response enhanced phase trigger signal X1. X1 acts on the adjustment module 120, and drives the converter module 130 to break through the steady-state operation limit through the transiently increased target voltage V1, and quickly releases the stored energy to provide a transient current to the output load.
[0044] According to an embodiment of the present disclosure, the circuit structure of the control module 110 can be any structure capable of detecting the change trend of the output load current or voltage, and is not limited herein.
[0045] According to an embodiment of the present disclosure, the regulation module 120 may include any number of flying capacitors, any number of power switches, and inductors, and regulate the voltage required by the output load 130' through a transient phase trigger signal.
[0046] Figure 1 It is only an equivalent schematic diagram of the circuit provided by the embodiment of the present disclosure, and the specific device composition is not shown. In the actual application process, the specific topology of the regulation module 120 can be determined according to the conversion ratio, the breakdown voltage of the power switch, the breakdown voltage of the flying capacitor, etc.
[0047] In addition to the regulation module 120 providing the target voltage for the converter module 130, solutions such as a low dropout regulator (LDO) can also be adopted, which are not limited herein.
[0048] According to an embodiment of the present disclosure, the control module detects a transient jump by the change trend of the current or voltage of the output load, and synchronously generates a transient response enhanced phase trigger signal. The regulation module switches the charge / discharge state of the first capacitor and the charge / demagnetization state of the first inductor according to the transient response enhanced phase trigger signal, instantaneously increases the target voltage input to the converter module, so that the converter module receives the transient response enhanced phase trigger signal, and provides a transient current for the output load according to the target voltage, so that the voltage drop speed of the output load meets a predetermined threshold. Therefore, for application scenarios with a large conversion ratio and large current, high efficiency can be achieved while a fast transient response can be realized.
[0049] Figure 2A Schematically shows a schematic diagram of an LLC converter circuit in the related art.
[0050] As Figure 2A shown, the LLC converter can use the turns ratio of the transformer to achieve voltage and current conversion with a large conversion ratio, and the design difficulty of the control circuit and the drive circuit is relatively low, and high voltage and large current are separated. Among them, the primary power switches S P1 and S P2 are resistant to the input voltage V IN , and only need to transmit a small current I OUT ×M (for 48V input and 1V output, M = 1 / 48). Although the secondary power switches S1 and S2 transmit a large current, their breakdown voltage is low. Therefore, the loss of the power switch tube is small and the converter efficiency is high.
[0051] Figure 2B Schematically shows Figure 2A the curve of the normalized voltage gain of the circuit shown in FIG. changing with the switching frequency.
[0052] As Figure 2BAs shown, the related art adjusts the conversion ratio of the converter by adjusting the switching frequency, and the normalized voltage gain M g The variation with the switching frequency can characterize the voltage regulation ability, which is related to the inductance coefficient λ of the transformer. The inductance L m is smaller, the inductance coefficient λ is larger, and the voltage regulation ability is stronger, but the efficiency of the transformer is lower.
[0053] Therefore, in order to improve the efficiency of the transformer, it is necessary to reduce the inductance coefficient λ of the transformer, that is, increase L m , but for applications with a large conversion ratio, it is difficult to achieve voltage regulation over a wide input and output range. And when the LLC converter operates at the resonance frequency points of L r and C r , the output rectification of the LLC converter is a continuous current and all power switching tubes operate in soft switching, and the converter efficiency is the highest. However, at this time, the normalized gain M g of the LLC converter is 1, and the conversion ratio of the converter is fixed at 1 / 2N, where N is the turns ratio of the primary and secondary sides of the transformer, that is, the voltage regulation ability is lost. It can be seen that there is an antagonistic relationship between the conversion efficiency and the voltage regulation ability of the LLC converter, and it is difficult to ensure both the conversion efficiency and the high voltage regulation ability at the same time.
[0054] Figure 2C Schematically shows Figure 2A The waveform diagram of the circuit shown in the case of a transient jump in the output load.
[0055] As Figure 2C shown, in response to a transient jump in the load current i O , the load capacitor C O immediately provides the current i CO for the output. The output current i LLC of the transformer lags behind the change in the load current I O , resulting in the impedance R eq of the converter from the secondary side equivalent to the primary side lagging behind the change in the load current I O , making it difficult for the input impedance R in of the LLC converter to follow the transient jump in a timely manner to provide a transient large current, resulting in a continuous drop in the output voltage V O until the output current i LLC of the transformer is equal to the load current I O . It can be seen that the LLC converter in the related art has the problem of slow load transient response. According to the embodiments of the present disclosure, the control module further includes: a steady-state control unit that generates a steady-state control signal in response to no transient jump in the output load; wherein, the adjustment module is further configured to adjust the charging / discharging duration of the first capacitor and the magnetization / demagnetization duration of the first inductor according to the steady-state control signal, so as to use the first capacitor to provide a target voltage for the converter module.
[0056] According to an embodiment of the present disclosure, when there is no transient jump in the output load, that is, in the steady state, the converter module operates at a fixed resonant frequency point, that is, the current normalized voltage gain M g is 1. Only the charge / discharge duration of the first capacitor and the charge / demagnetization duration of the first inductor in the energy storage unit composed of the first capacitor and the first inductor need to be adjusted. By using the charge conservation of the first capacitor during charging / discharging (charging charge Q charge = discharging charge Q discharge ), the current of the first inductor and the output current of the converter module are automatically balanced without the need to additionally set up a feedback circuit.
[0057] According to an embodiment of the present disclosure, when there is no transient jump in the output load, that is, in the stable state, the steady-state control unit generates a steady-state control signal X2. Without adjusting the switching frequency, by adjusting the charge of the first capacitor, a stable target voltage is provided for the converter module, ensuring that the conversion efficiency and voltage regulation ability of the converter module are decoupled. At the same time, system oscillation caused by frequent adjustment is avoided.
[0058] According to an embodiment of the present disclosure, the adjustment module further includes a first power switch and a second power switch; the first end of the first power switch is connected to the input end of the adjustment module, the second end is connected to the first end of the first capacitor, and a first node is included between the first end of the first capacitor and the second end of the first power switch. The first node is connected to the converter module. The second end of the first capacitor is connected to the first end of the first inductor, and a second node is included between the second end of the first capacitor and the first end of the first inductor. The second node is connected to the first end of the second power switch, and the second end of the second power switch is grounded.
[0059] According to an embodiment of the present disclosure, the converter module includes a transformer. The primary side of the transformer includes a first primary switch, a second primary switch, a resonant inductor, and a resonant capacitor. The secondary side of the transformer includes a first secondary switch and a second secondary switch. The first end of the first primary switch is connected to the adjustment module, the second end is connected to the second primary switch, and a third node is included between the first primary switch and the second primary switch. The third node is connected to a series unit including a resonant inductor and a resonant capacitor.
[0060] For a better understanding of the above circuit connection relationship, the following will take the power supply scenario of 48V input and 1V output as an example, with the turns ratio of the transformer being 20:1:1, and will be described in detail through Figure 3 this.
[0061] Figure 3 Schematically shows a circuit diagram for improving the load transient response speed of an LLC converter according to an embodiment of the present disclosure.
[0062] As Figure 3As shown, for convenience, the specific circuit of the control module is not shown temporarily. In the adjustment module, the first power switch S AH and the second power switch S AL ; The first end of the first power switch S AH is connected to the input end of the adjustment module, that is, the input voltage V IN , the second end is connected to the first end of the first capacitor C F , and between the first end of the first capacitor C F and the second end of the first power switch S AH there is a first node (the voltage at this node is denoted as V SW3 ), the first node is connected to the converter module, the second end of the first capacitor C F is connected to the first end of the first inductor L, and between the second end of the first capacitor C F and the first end of the first inductor L there is a second node (the voltage at this node is denoted as V SW1 ), the second node is connected to the first end of the second power switch S AL , the second end of the second power switch S AL is grounded, the first node is connected to the first primary switch S BH , the second end of the first primary switch S BH is connected to the second primary switch S BL , the first node is connected to the series unit, the series unit includes a resonant capacitor C r and a resonant inductor L r , the secondary side of the transformer includes a first secondary switch S1 grounded and a second secondary switch S2 grounded.
[0063] According to an embodiment of the present disclosure, the second power switch, the first primary switch, the second primary switch, the first secondary switch, and the second secondary switch all operate in the soft-switching mode, and the second power switch, the first primary switch, and the second primary switch are in the zero-voltage switching mode, and the first secondary switch and the second secondary switch are in the zero-current switching mode.
[0064] According to an embodiment of the present disclosure, the second power switch, the first primary switch, and the second primary switch select the zero-voltage switching mode, which can avoid large losses during switch turn-on and turn-off and improve the efficiency of the converter. The first secondary switch and the second secondary switch select the zero-current mode, which can avoid overlap losses during switch turn-on and turn-off and improve the efficiency of the converter.
[0065] According to an embodiment of the present disclosure, the control module is further configured to: in response to a transient jump in the output load, adjust the duty cycle of each of the multiple phases within a single operating cycle to obtain a transient duty cycle; in response to no transient jump in the output load, adjust the duty cycle of each of the multiple phases within a single operating cycle to obtain a steady-state duty cycle.
[0066] Under the condition that there is no transient jump in the output load, the steady-state duty ratio controls the charging / discharging of the first capacitor and the magnetization / demagnetization of the first inductor, and does not trigger the transient response enhancement phase.
[0067] According to an embodiment of the present disclosure, multiple phases include a transient response enhancement phase. In the transient response enhancement phase, the second primary switch, the second power switch, and the first secondary switch are turned off, and the first primary switch, the first power switch, and the second secondary switch are turned on, and the power supply voltage is used as the target voltage. The multiple phases further include a first phase, a second phase, and a third phase; in the first phase, the second power switch, the first primary switch, and the second secondary switch are turned off, the first power switch, the second primary switch, and the first secondary switch are turned on, the first inductor is magnetized, and the first capacitor is charged; in the second phase, the first power switch, the first primary switch, and the second secondary switch are turned off, the second power switch, the second primary switch, and the first secondary switch are turned on, and the first inductor is demagnetized; in the third phase, the first power switch, the second primary switch, and the first secondary switch are turned off, the second power switch, the first primary switch, and the second secondary switch are turned on, and the first inductor is demagnetized.
[0068] Figure 4 Schematically shows Figure 3 The equivalent circuit diagram of the shown circuit in the transient response enhancement phase.
[0069] As Figure 4 shown, the second primary switch S BL , the second power switch S AL and the first secondary switch S1 are turned off, the first primary switch S BH , the first power switch S AH and the second secondary switch S2 are turned on, and the input voltage of the adjustment module, that is, the power supply voltage V IN provides the target voltage for the converter module, and the converter module immediately provides a transient current.
[0070] Figure 5 Schematically shows Figure 3 The equivalent circuit diagram of the shown circuit in the first phase.
[0071] As Figure 5 shown, in the first phase (phase1), the second power switch S AL , the first primary switch S BH and the second secondary switch S2 are turned off, the first power switch S AH , the second primary switch S BL and the first secondary switch S1 are turned on, the first inductor L is magnetized, and the first capacitor C F is charged.
[0072] Figure 6 Schematically shows Figure 3Equivalent circuit diagram of the shown circuit in the second phase.
[0073] As Figure 6 shown, in the second phase (phase2), the first power switch S AH , the first primary switch S BH and the second secondary switch S2 are turned off, the second power switch S AL , the second primary switch S BL and the first secondary switch S1 are turned on, and the first inductor L demagnetizes.
[0074] Figure 7 Schematically shows Figure 3 the equivalent circuit diagram of the shown circuit in the third phase.
[0075] As Figure 7 shown, in the third phase (phase3), the first power switch S AH , the second primary switch S BL and the first secondary switch S1 are turned off, the second power switch S AL , the first primary switch S BH and the second secondary switch S2 are turned on, and the first inductor L demagnetizes. At the same time, C F provides charge for the converter module to discharge the output load, and the discharged charge is equal to the charge that C F is charged by the first inductor L during Phase1 and the transient response enhancement phase.
[0076] It can be seen therefrom that the circuit includes 6 power switches, and at most only 3 power switches are on the power path. Compared with the related technology where at least 4 power switches are required on the power path, the circuit power consumption is reduced, and the conversion efficiency of the converter module is improved.
[0077] According to an embodiment of the present disclosure, the control module is further configured to: in response to a transient jump of the output load, adjust the duty ratio of the first phase to a preset threshold and set the second phase to 0; in response to no transient jump of the output load, set the transient response enhancement phase to 0 and adjust the duty ratio of the third phase to a preset threshold, where the preset threshold may be 0.5.
[0078] According to an embodiment of the present disclosure, for the case where the transformer turns ratio of the converter module is 20:1:1, the conversion ratio is 1 / 40, and the proportional relationship between the input voltage and the output voltage of the converter module is fixed, that is, the input voltage is 40 times the output voltage.
[0079] For the entire circuit, the first capacitor supplies power to the converter module. In the steady state, the first capacitor provides a stable input voltage (i.e., the target voltage) for the converter. Therefore, the steady-state voltage of the first capacitor is 40V O, according to the volt - second balance of the first inductor, the following formula (1) can be obtained.
[0080] (1)
[0081] Where D represents the duty cycle of the first phase, is the conversion ratio.
[0082] It can be seen from this that voltage regulation can be achieved by adjusting the duty cycle D of the first phase. The voltage conversion ratio range is (0, 1 / 42), and the equivalent conduction time is extended to 42 times that of the traditional Buck circuit.
[0083] According to an embodiment of the present disclosure, the following formulas (2) and (3) can be obtained according to the charge conservation of the charging and discharging of the first capacitor.
[0084] (2)
[0085] (3)
[0086] Where i L is the average current of the first inductor, which is related to the magnetization process of the first inductor and is used to reflect the average magnitude of the inductor current during the charging period of the first capacitor. T represents the period, and DT represents the duration of the first phase. i LLC represents the current provided to the output load when the first capacitor discharges through the converter module. 0.5T represents the duration of the third phase.
[0087] Figure 8A Schematically shows Figure 3 the waveform diagram of the circuit shown in the steady state.
[0088] Figure 8B Schematically shows Figure 3 the circuit flow diagram of the circuit shown in the steady state.
[0089] As Figure 8A and 8B shown, in the first phase, S AH , S BL and S1 are turned on, S AL , S BH and S2 are turned off. At this time, the first capacitor C F is charged by the first inductor L, the first inductor L is magnetized, and the first inductor current i L rises. The first phase lasts for a duration of DT; in the second phase, S AL , S BL and S1 are turned on, S AH , S BH and S2 are turned off. At this time, the first capacitor C FSuspended, the first inductor L demagnetizes, and the first inductor current i L decreases, and the second phase lasts for (0.5 - D)T; in the third phase, S AH 、S BL and S1 turn off, and S AL 、S BH and S2 turn on. At this time, the first capacitor C F provides charge for the converter module, and the discharged charge is equal to the charge charged by the first inductor L in the first phase. At the same time, the first inductor L demagnetizes, and the first inductor current i L decreases, and the third phase lasts for 0.5T. In the steady state, within one working cycle, the first phase, the second phase, and the third phase are alternately triggered, and the duty cycle of the transient response enhancement phase is 0 and is not triggered.
[0090] Figure 9A Schematically shows Figure 3 the waveform diagram of the circuit shown in transient response.
[0091] Figure 9B Schematically shows Figure 3 the circuit flow diagram of the circuit shown in transient response.
[0092] As Figure 9A and Figure 9B shown, in the first phase, S AH 、S BL and S1 turn on, and S AL 、S BH and S2 turn off. At this time, the first capacitor C F is charged by the first inductor L, the first inductor L magnetizes, and the first inductor current i L rises, and the first phase lasts for 0.5T; in the transient response enhancement phase, S AH 、S BH and S2 turn on, and S AL 、S BL and S1 turn off. At this time, the first capacitor C F is continuously charged by the first inductor L, the first inductor L magnetizes, and the first inductor current i L rises. Since the power supply voltage is higher than 40V O of V IN powers the converter module, the slope of the resonant inductor L r changes from 20 - V Cr in the steady state to V IN -V Cr -20V O . Since V IN > 40V O , therefore, the current i Lr of the resonant inductor rises rapidly, and the output current i LLCThe rapid rise provides a transient large current for the output load, and the duration of the transient response enhancement phase is D tran T, where D tran represents the duty cycle of the transient response enhancement phase; in the second phase, S AL 、S BL and S1 are turned on, and S AH 、S BH and S2 are turned off. At this time, the first capacitor C F is floating, the first inductor L demagnetizes, and the first inductor current i L decreases. The duration of the second phase is (0.5 - D tran )T. Under transient conditions, within one working cycle, the first phase, the transient response enhancement phase, and the third phase are alternately triggered, and the duty cycle of the second phase is 0 and is not triggered. The circuit diagrams and flowcharts in the accompanying drawings illustrate the possible architectures, functions, and operations of the circuits according to various embodiments of the present disclosure. Those skilled in the art can understand that the features described in the various embodiments of the present disclosure can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present disclosure. In particular, without departing from the spirit and teachings of the present disclosure, the features described in the various embodiments of the present disclosure can be combined and / or combined in various ways. All such combinations and / or combinations fall within the scope of the present disclosure.
[0093] The above describes the embodiments of the present disclosure. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although the embodiments are described separately above, this does not mean that the measures in the respective embodiments cannot be used advantageously in combination. Without departing from the scope of the present disclosure, those skilled in the art can make various substitutions and modifications, and all such substitutions and modifications should fall within the scope of the present disclosure.
Claims
1. A circuit for improving the load transient response speed of an LLC converter, comprising: A control module, including a transient control unit, wherein the transient control unit generates a transient response enhanced phase trigger signal in response to a transient jump in the output load; An adjustment module, including a first capacitor and a first inductor, the adjustment module is used to switch the charge / discharge state of the first capacitor and the charge / demagnetization state of the first inductor according to the transient response enhanced phase trigger signal, and instantaneously increase the target voltage input to the converter module; The converter module, in response to receiving the transient response enhanced phase trigger signal, provides a transient current for the output load according to the target voltage to reduce the voltage drop speed and amplitude of the output load.
2. The circuit according to claim 1, wherein The control module further includes: A steady-state control unit, which generates a steady-state control signal in response to no transient jump in the output load; Wherein, the adjustment module is further used to adjust the charge / discharge duration of the first capacitor and the charge / demagnetization duration of the first inductor according to the steady-state control signal, so as to use the first capacitor to provide the target voltage for the converter module.
3. The circuit according to claim 1, wherein, The adjustment module further includes a first power switch and a second power switch; the first end of the first power switch is connected to the input end of the adjustment module, the second end is connected to the first end of the first capacitor, and a first node is included between the first end of the first capacitor and the second end of the first power switch, the first node is connected to the converter module, the second end of the first capacitor is connected to the first end of the first inductor, and a second node is included between the second end of the first capacitor and the first end of the first inductor, the second node is connected to the first end of the second power switch, and the second end of the second power switch is grounded.
4. The circuit according to claim 3, wherein, The converter module includes a transformer, the primary side of the transformer includes a first primary switch, a second primary switch, a resonant inductor and a resonant capacitor, the secondary side of the transformer includes a first secondary switch and a second secondary switch, the first end of the first primary switch is connected to the adjustment module, the second end of the first primary switch is connected to the second primary switch, a third node is included between the first primary switch and the second primary switch, and the third node is connected to a series unit including the resonant inductor and the resonant capacitor.
5. The circuit according to claim 2, wherein The control module is further used for: In response to a transient jump in the output load, adjusting the duty cycle of each of multiple phases within a single working cycle to obtain a transient duty cycle; In response to no transient jump in the output load, adjusting the duty cycle of each of multiple phases within a single working cycle to obtain a steady-state duty cycle.
6. The circuit according to claim 5, wherein, The multiple phases include a transient response enhanced phase, in which the second primary switch, the second power switch and the first secondary switch are turned off, the first primary switch, the first power switch and the second secondary switch are turned on, and the power supply voltage is used as the target voltage.
7. The circuit according to claim 6, wherein, The multiple phases further include a first phase, a second phase and a third phase; In the first phase, the second power switch, the first primary switch, and the second secondary switch are turned off, the first power switch, the second primary switch, and the first secondary switch are turned on, the first inductor is magnetized, and the first capacitor is charged; In the second phase, the first power switch, the first primary switch, and the second secondary switch are turned off, the second power switch, the second primary switch, and the first secondary switch are turned on, and the first inductor is demagnetized; In the third phase, the first power switch, the second primary switch, and the first secondary switch are turned off, the second power switch, the first primary switch, and the second secondary switch are turned on, the first inductor is demagnetized, and the first capacitor is discharged.
8. The circuit according to claim 7, wherein The control module is further configured to: In response to a transient jump in the output load, adjust the duty cycle of the first phase to a preset threshold and set the second phase to 0; In response to no transient jump in the output load, set the transient response enhancement phase to 0 and adjust the duty cycle of the third phase to a preset threshold.
9. The circuit according to claim 8, wherein, The preset threshold is 0.
5.
10. The circuit according to claim 4, wherein, The second power switch, the first primary switch, the second primary switch, the first secondary switch, and the second secondary switch all operate in the soft-switching mode, and the second power switch, the first primary switch, and the second primary switch are in the zero-voltage switching mode, while the first secondary switch and the second secondary switch are in the zero-current switching mode.