Transient inductance voltage regulator for secondary side energy recovery and control strategy thereof

Abstract

The invention provides a transient inductance voltage regulator for secondary side energy recovery and a control strategy thereof to solve the problems that an existing transient inductance voltage regulator is low in efficiency and large in loss. According to the invention, the active switch is additionally arranged on the secondary side, the control circuit can be switched between a traditional staggered Buck VRM and a TLVR, the circuit works in a staggered Buck VRM mode in a steady state, and high steady-state efficiency is realized; in a transient state, the circuit works in a TLVR mode, and high dynamic performance is realized; and when the auxiliary switch tube is switched off, the secondary current can flow back to the power supply through the auxiliary diode, and the energy stored by the secondary side in the transient state is recovered to the power supply, so that the overall operation efficiency of the circuit is improved. The method has the advantages of high efficiency, stability, reliability, simplicity in control and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power electronics, in particular to a trans- inductor voltage regulator with energy recovery on secondary side and a control strategy thereof. BACKGROUND

[0002] With the rapid development of emerging information technologies such as big data, artificial intelligence, blockchain and cloud computing, large data centers for data computing, processing and storage have also developed rapidly and become important infrastructure in modern society. The chip integration and core number of CPU / GPU / TPU / ASIC used by servers, AI, etc. are increasing, and the chip has the characteristics of continuously decreasing operating voltage (0.8-1.8V) and continuously increasing power consumption, power supply current and dynamic response. The single-chip power supply current can reach hundreds of amperes, and the dynamic response is above 1000A / μs, which puts higher requirements on the power supply capability and dynamic response speed of the chip power supply.

[0003] The conventional chip power supply circuit topology is relatively mature in structure, mainly adopting a multi-phase interleaved Buck circuit (i.e. multi-phase interleaved Buck VRM) as shown in Figure 1 . The interleaved parallel connection makes the total current ripple smaller due to the mutual cancellation of the ripples, and each phase Buck can use a smaller inductance, thereby effectively improving the dynamic response speed. Moreover, through parallel connection, the increasing current demand of the chip can also be met.

[0004] The Buck circuits of the ordinary multi-phase interleaved Buck VRM are decoupled controlled, and each phase Buck circuit independently responds within several switching periods after the output load jumps. To speed up the transient response speed, it is necessary to consider how to make each phase Buck circuit work cooperatively. When the load jumps, the output current of a certain phase Buck circuit changes, and the current of other phases changes accordingly, thereby making the output current change rapidly. Therefore, a trans-inductor voltage regulator (TLVR) is proposed as shown in Figure 2 .

[0005] The TLVR changes the inductor L n of the multi-phase interleaved Buck VRM into the transformer with the primary self-inductance L n , the secondary coil of the transformer is connected in series with the coupling inductor L c . Each phase is still controlled in interleaved parallel connection, and the phase difference of each phase is 2π / n , n .

[0006] By adding a secondary side to a multiphase Buck converter, the rate of change of the total inductor current during transients is significantly increased due to the coupling effect between phases, thus improving dynamic performance. However, this also brings some negative issues, mainly: (1) Compared to multiphase interleaved Buck VRM, the single-phase current ripple and total current ripple of TLVR both increase, leading to increased switching losses and core losses; and the secondary side ripple current frequency of TLVR is n The high switching frequency, which is several times higher than the standard frequency, leads to increased line losses and coupling inductance. L c The high loss of the inductor core further reduces the steady-state efficiency.

[0007] (2) During transient states, the secondary inductor stores a large amount of reactive energy, which can only be slowly consumed through the parasitic resistance of the secondary circuit, resulting in significant losses. Summary of the Invention

[0008] The purpose of this invention is to provide a transient inductor voltage regulator for secondary-side energy recovery and its control strategy. This transient inductor voltage regulator has high operating efficiency and good transient performance.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is: a transient inductor voltage regulator with secondary-side energy recovery, characterized in that the circuit topology of the transient inductor voltage regulator with secondary-side energy recovery includes: several basic units connected in parallel, and an output capacitor. C o Auxiliary switching transistor S bp1 , S bp2 and auxiliary diodes D 1. D 2; among which, auxiliary switching transistor S bp1 With auxiliary diode D Group 1 is the first group, forming the first half-bridge arm, with auxiliary diodes. D The cathode of 1 is connected to the positive terminal of the input voltage. V i Auxiliary diode D 1's anode and auxiliary switching transistor S bp1 Drain connection, auxiliary switching transistor S bp1 The source is grounded; auxiliary switching transistor S bp2 With auxiliary diode D Group 2 is the second group, forming the second half-bridge arm, and the connection method is the same as that of the first group.

[0010] Furthermore, the basic unit includes: a switching transistor. Sn1 and S n2 and transformers T n ; S n1 The source pole and S n2 The drain connections form the half-bridge arms. S n1 The drain is connected to the positive terminal of the input voltage. S n2 The source pole is connected to the ground. S n1 and S n2 These are the upper and lower tubes of the half-bridge arm, respectively; transformer. T n Contains two windings N p and N s These are the primary winding and the secondary winding, respectively, with self-inductances of the two windings being respectively... L n and L n0 The mutual inductance of the two windings is M n0 ;of which the primary winding N p One end connection S n1 and S n2 The half-bridge arm is connected to the midpoint of its structure, with the other end connected to the output capacitor. C o and load; secondary windings of all basic units N s The two half-bridge arms are connected in series and the midpoints of the auxiliary switching transistor and auxiliary diode are connected at both ends.

[0011] Furthermore, the secondary windings of all basic units N s After being connected in series, one end is coupled to an inductor via the secondary side. L c Connect the midpoint of the first half-bridge arm, and connect the other end directly to the midpoint of the second half-bridge arm.

[0012] Furthermore, the switching transistor S n1 and S n2 MOSFETs are used.

[0013] Furthermore, the switching transistor S n1 and Sn2 GaN HEMT is used.

[0014] Furthermore, the auxiliary diode D 1 and D 2. Discrete diodes are used, and the auxiliary switching transistor is... S bp1 and S bp2 Discrete MOSFETs are used.

[0015] Furthermore, the auxiliary diode D 1 and D 2. Discrete MOSFETs are used, and the auxiliary switching transistor... S bp1 and S bp2 Discrete MOSFETs are used.

[0016] Furthermore, the auxiliary switching transistor S bp1 With auxiliary diode D Group 1 is the first group, employing an integrated half-bridge MOSFET; the auxiliary switching transistor S bp2 With auxiliary diode D Group 2 is the second group, which uses an integrated half-bridge MOSFET.

[0017] The present invention also provides a control strategy for the transient inductor voltage regulator for secondary-side energy recovery, comprising the following steps: Step S1: The controller determines whether the load current has changed by detecting the output voltage fluctuation. If the output voltage and the rate of change of the output voltage change exceed the set value within the set time, it is determined that the load current has changed and proceeds to step S2. Step S2: After the controller detects a jump in the load current, it controls the auxiliary switching transistor. S bp1 and S bp2 Simultaneously launched; Step S3: The controller checks whether the output voltage has returned to a steady-state value. If it has, it controls the auxiliary switching transistor. S bp1 and S bp2 Shut down at the same time.

[0018] Compared with existing technologies, this invention has the following advantages: This invention provides a transient inductor voltage regulator with secondary-side energy recovery and its control strategy to solve the problems of low efficiency and high losses in existing transient inductor voltage regulators. By adding an active switch on the secondary side, the control circuit can switch between traditional interleaved Buck VRM and TLVR modes. In steady state, the circuit operates in interleaved Buck VRM mode, achieving high steady-state efficiency; in transient state, the circuit operates in TLVR mode, achieving high dynamic performance. Furthermore, when the auxiliary switch is turned off, the secondary-side current can flow back to the power supply through the auxiliary diode, recovering the energy stored on the secondary side during transient states back to the power supply, thereby improving the overall operating efficiency of the circuit. This invention has the advantages of high efficiency, stability, reliability, and simple control. Attached Figure Description

[0019] Figure 1 This is a traditional interleaved Buck VRM circuit topology; Figure 2 This is a circuit topology diagram of a traditional transient inductor voltage regulator (TLVR); Figure 3 This is a circuit topology diagram of a transient inductor voltage regulator for secondary-side energy recovery according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the control strategy of the transient inductor voltage regulator for secondary-side energy recovery according to an embodiment of the present invention; Figure 5 This is a simulation waveform diagram of the transient inductor voltage regulator for secondary-side energy recovery according to an embodiment of the present invention. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0022] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] As mentioned above, the integration and core count of CPU / GPU / TPU / ASIC chips used in servers, AI, etc. are increasing. These chips are characterized by continuously decreasing operating voltage (0.8-1.8V) while continuously increasing power consumption, supply current, and dynamic response. Currently, the supply current of a single chip can reach hundreds of amperes, and the dynamic current can reach more than 1000A / μs. This places high demands on the power supply capacity and dynamic performance of the chip power supply.

[0024] Traditional interleaved buck voltage regulators (TLVRs) rely on independent phase control, making it increasingly difficult to meet the dynamic requirements of chip power supply. Therefore, transient inductor voltage regulators were proposed. However, TLVRs replace the discrete inductors in interleaved buck voltage regulators with transformers, increasing the secondary circuit and leading to increased current ripple. Furthermore, continuous reactive power consumption on the secondary side results in lower efficiency.

[0025] Figure 1 This is a traditional interleaved Buck VRM circuit topology, in which V i The positive terminal of the input voltage. S n1 and S n2 It is a half-bridge switching transistor. L n For filtering inductors, C o This is the output filter capacitor. S n1 , S n2 and L n The basic unit that constitutes the interleaved Buck VRM is the circuit composed of several units connected in parallel.

[0026] Figure 2 This is a traditional transient inductor voltage regulator (TLVR) circuit topology, similar in structure to a traditional interleaved Buck VRM, but with the filter inductor replaced by a... L n The transformer has a primary-side self-inductance, and the secondary-side self-inductance is... L n0 Then, the secondary windings of all transformers are connected in series and grounded on both sides to form a secondary circuit.

[0027] Therefore, this invention proposes a transient inductor voltage regulator with secondary-side energy recovery. In steady state, it operates in the high-efficiency interleaved Buck VRM mode, while in transient state, it operates in the good transient performance TLVR mode. It can also feed back the reactive power stored in the secondary-side coupled inductor during dynamic periods to the input side. It has the characteristics of high circuit efficiency and excellent dynamic performance, effectively overcoming the shortcomings of traditional interleaved Buck VRM which has high efficiency but poor dynamic performance, and existing TLVR which has excellent dynamic performance but low efficiency.

[0028] Figure 3 This diagram shows the circuit topology of the transient inductor voltage regulator with secondary-side energy recovery provided in this embodiment. Based on a traditional TLVR, the transient inductor voltage regulator with secondary-side energy recovery adds a set of diodes and switching transistors on both sides of the secondary side to form a half-bridge structure. Its circuit topology includes: several basic units connected in parallel, and an output capacitor. C o Secondary-side coupled inductor L c Auxiliary switching transistor S bp1 , S bp2 and auxiliary diodes D 1. D 2. Among them, the auxiliary switching transistor S bp1 With auxiliary diode D Group 1 is the first group, forming the first half-bridge arm, with auxiliary diodes. D The cathode of 1 is connected to the positive terminal of the input voltage. V i Auxiliary diode D 1's anode is connected to the auxiliary switching transistor. S bp1 The drain of the transistor is connected to the secondary circuit as the midpoint of the half-bridge, serving as an auxiliary switching transistor. S bp1 The source is grounded; auxiliary switching transistor S bp2 With auxiliary diode D Group 2 forms the second half-bridge arm, with auxiliary diodes. D The cathode of 2 is connected to the positive terminal of the input voltage. V i Auxiliary diode D 2's anode is connected to the auxiliary switch tube. S bp2 The drain of the transistor is connected to the secondary circuit as the midpoint of the half-bridge, serving as an auxiliary switching transistor. S bp2 The source electrode is grounded.

[0029] The basic unit includes: a switching transistor. S n1and S n2 and transformers T n ; S n1 The source pole and S n2 The drain connections form the half-bridge arms. S n1 The drain is connected to the positive terminal of the input voltage. S n2 The source pole is connected to the ground. S n1 and S n2 These are the upper and lower tubes of the half-bridge arm, respectively; transformer. T n Contains two windings N p and N s These are the primary winding and the secondary winding, respectively, with self-inductances of the two windings being respectively... L n and L n0 The mutual inductance of the two windings is M n0 ;of which the primary winding N p One end connection S n1 and S n2 The half-bridge arm is connected to the midpoint of its structure, with the other end connected to the output capacitor. C o and load; secondary windings of all basic units N s They are connected in series, and then one end is coupled to an inductor via the secondary side. L c Connect the midpoint of the first half-bridge arm, and connect the other end directly to the midpoint of the second half-bridge arm.

[0030] Preferably, the switching transistor S n1 and S n2 MOSFETs or GaN HEMTs can be used.

[0031] The auxiliary diode D 1 and D 2 can be a discrete diode or a discrete MOSFET; the auxiliary switching transistor S bp1 and S bp2 Discrete MOSFETs can be used.

[0032] The auxiliary switching transistor S bp1 With auxiliary diode D Group 1 is the first group, which can use integrated half-bridge MOSFETs; the auxiliary switching transistor S bp2 With auxiliary diode D Group 2 is the second group, which can use integrated half-bridge MOSFETs.

[0033] Therefore, in controlling the auxiliary switching transistor S bp1 and S bp2 When turned off, the secondary circuit is disconnected, and the circuit is equivalent to a traditional interleaved Buck VRM; this is achieved by controlling the auxiliary switching transistor. S bp1 and S bp2 When activated, the secondary circuit is activated, and the circuit is equivalent to TLVR.

[0034] The present invention also provides a control strategy for the transient inductor voltage regulator for secondary-side energy recovery, so as to control the turn-on and turn-off of the auxiliary switch, thereby controlling the flow of secondary-side current.

[0035] In this embodiment, the control strategy includes the following steps: Step S1: The controller determines whether the load current has changed by detecting output voltage fluctuations. Step S1: The controller determines whether the load current has changed by detecting the output voltage fluctuation. If the output voltage drops or overshoots significantly in a short period of time, that is, the output voltage and the rate of change of the output voltage (i.e., the derivative and slope of the output voltage) change more than the set value within a set time, then it is determined that the load current has changed and proceeds to step S2.

[0036] Step S2: After the controller detects a jump in the load current, it controls the auxiliary switching transistor. S bp1 and S bp2 Simultaneous activation converts the circuit mode to TLVR, causing the secondary current to change rapidly.

[0037] Step S3: The controller checks whether the output voltage has returned to a steady-state value. If it has, it controls the auxiliary switching transistor. S bp1 and S bp2 Simultaneously, it is turned off, causing the circuit mode to switch to a normal interleaved Buck VRM.

[0038] Auxiliary switching transistor S bp1 and Sbp2 After being turned off, if there is still a large current on the secondary side, it will flow through the auxiliary diode D1 and the auxiliary switching transistor. S bp2 The body diode freewheels and feeds the inductor energy back to the power supply, or through the auxiliary diode D2 and the auxiliary switching transistor. S bp1 The body diode freewheels and feeds the energy from the inductor back to the power supply.

[0039] When the circuit is operating in steady state, let S bp1 and S bp2 Both sides are disconnected. At this time, there is no conducting loop on the secondary side, and it is completely disconnected. Therefore, the circuit topology is equivalent to... Figure 1 The traditional interleaved Buck VRM. When the circuit enters transient operation, it causes... S bp1 and S bp2 Both sides are turned on, and at this time the two ends of the secondary side are grounded, so the circuit topology is equivalent to Figure 2 Traditional TLVR is used to improve transient performance. When the circuit exits transient operation, it makes... S bp1 and S bp2 When the secondary side is turned off, the secondary current naturally flows through the body diode and the auxiliary diode of the auxiliary switch, feeding the reactive power back to the power supply. After the secondary current drops to 0, the diodes naturally turn off and return to steady state.

[0040] Figure 4 These are the key control waveforms of the transient inductor voltage regulator for secondary-side energy recovery in this embodiment. Among them, I load For load current, v o For output voltage, G bp These are the drive signals for the two auxiliary switching transistors. i Lc This is the secondary current, i.e., the secondary coupled inductance. L c Electric current.

[0041] exist t Before time 0, load current I load The voltage is relatively small and in a steady state, with a low output voltage. v o Constant, auxiliary switch drive signal G bp When the value is 0, the secondary side is turned off, and the circuit is equivalent to... Figure 1 Traditional interleaved Buck VRM.

[0042] existt At time 0, the load current I load The sudden increase causes the output voltage to rise. v o The voltage drops rapidly. Therefore, the controller detects the output voltage. v o In a rapid drop state, the auxiliary switch drive signal is set high. G bp The auxiliary switch is turned on.

[0043] exist t 0- t At time 1, the circuit topology is equivalent to Figure 2 Traditional TLVR mode, secondary current i Lc Rapid changes in voltage lead to changes in the primary-side current, enhancing the circuit's transient response capability, thus increasing the output voltage. v o It quickly recovers to its steady-state value.

[0044] exist t At time 1, the controller detects that the output voltage has recovered to its steady-state value, and therefore resets the auxiliary switching transistor drive signal to zero. G bp Turn off the auxiliary switch. At this time, the secondary current... i Lc If the value is not zero, it means that the secondary inductor still stores some reactive power. Therefore, the secondary current will continue to be freewheeled by the auxiliary diode and the body diode of the auxiliary switch, feeding the reactive power stored in the secondary inductor back to the power supply.

[0045] exist t At time 2, the secondary current i Lc When the value is 0, all the reactive power stored in the secondary inductor has been fed back to the power supply. The body diodes of the auxiliary diode and the auxiliary switching transistor naturally turn off, and the circuit mode returns to zero. Figure 1 Traditional interleaved Buck VRM modality.

[0046] exist t At time 3, due to a sudden drop in output current, the output voltage... v o The voltage rises rapidly. The controller also detects the output voltage. v o In a rapid overshoot state, the auxiliary switch drive signal is set high. G bp The auxiliary switch is turned on. The subsequent control and response process is... t 0- t The two time periods are similar, and the output voltage is to be output. v oAfter the system returns to steady state, the auxiliary switch is turned off, and the secondary side energy is recovered by the power supply.

[0047] Figure 5 These are the key simulation waveforms for the transient inductor voltage regulator with secondary-side energy recovery in this embodiment. The first window represents the output voltage. v o Waveform; the second window shows the load current. i load and total inductor current waveform i L_all The third window represents the primary inductor current of each phase. i L_ph The fourth window represents the secondary current of the TLVR. i Lc and secondary auxiliary switch drive signal G bp Observation of the simulation waveforms shows that the simulation results are consistent with the proposed theory.

[0048] In summary, the transient inductor voltage regulator for secondary-side energy recovery and its control strategy provided by this invention have at least the following advantages: (1) The secondary side is fully controllable, which facilitates switching between TLVR and interleaved Buck VRM to improve dynamic performance and steady-state efficiency; (2) The energy stored on the secondary side during transients can be fed back to the power source to improve efficiency; (3) The secondary side can be turned off at any time, and there is no turn-off spike problem, which simplifies control and improves stability; (4) It is simple to implement. The auxiliary switching transistors and diodes can be directly implemented using integrated half-bridge chips or discrete MOSFETs + diodes, which is low cost.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A transient inductor voltage regulator for secondary-side energy recovery, characterized in that, The circuit topology of the transient inductor voltage regulator for secondary-side energy recovery includes: several basic units connected in parallel, and an output capacitor. C o Auxiliary switching transistor S bp1 , S bp2 and auxiliary diodes D 1. D 2; among which, auxiliary switching transistor S bp1 With auxiliary diode D Group 1 is the first group, forming the first half-bridge arm, with auxiliary diodes. D The cathode of 1 is connected to the positive terminal of the input voltage. V i Auxiliary diode D 1's anode and auxiliary switching transistor S bp1 Drain connection, auxiliary switching transistor S bp1 The source is grounded; auxiliary switching transistor S bp2 With auxiliary diode D Group 2 is the second group, forming the second half-bridge arm, and the connection method is the same as that of the first group.

2. The transient inductor voltage regulator for secondary-side energy recovery according to claim 1, characterized in that, The basic unit includes: a switching transistor. S n1 and S n2 and transformers T n ; S n1 The source pole and S n2 The drain connections form the half-bridge arms. S n1 The drain is connected to the positive terminal of the input voltage. S n2 The source pole is connected to the ground. S n1 and S n2 These are the upper and lower tubes of the half-bridge arm, respectively; transformer. T n Contains two windings N p and N s These are the primary winding and the secondary winding, respectively, with self-inductances of the two windings being respectively... L n and L n0 The mutual inductance of the two windings is M n0 ;of which the primary winding N p One end connection S n1 and S n2 The half-bridge arm is connected to the midpoint of its structure, with the other end connected to the output capacitor. C o and load; secondary windings of all basic units N s The two half-bridge arms are connected in series and the midpoints of the auxiliary switching transistor and auxiliary diode are connected at both ends.

3. A transient inductor voltage regulator for secondary-side energy recovery according to claim 2, characterized in that, Secondary windings of all basic units N s After being connected in series, one end is coupled to an inductor via the secondary side. L c Connect the midpoint of the first half-bridge arm, and connect the other end directly to the midpoint of the second half-bridge arm.

4. A transient inductor voltage regulator for secondary-side energy recovery according to claim 2, characterized in that, The switching transistor S n1 and S n2 MOSFETs are used.

5. A transient inductor voltage regulator for secondary-side energy recovery according to claim 2, characterized in that, The switching transistor S n1 and S n2 GaN HEMT is used.

6. A transient inductor voltage regulator for secondary-side energy recovery according to claim 1, characterized in that, The auxiliary diode D 1 and D 2. Discrete diodes are used, and the auxiliary switching transistor is... S bp1 and S bp2 Discrete MOSFETs are used.

7. A transient inductor voltage regulator for secondary-side energy recovery according to claim 1, characterized in that, The auxiliary diode D 1 and D 2. Discrete MOSFETs are used, and the auxiliary switching transistor... S bp1 and S bp2 Discrete MOSFETs are used.

8. A transient inductor voltage regulator for secondary-side energy recovery according to claim 1, characterized in that, The auxiliary switching transistor S bp1 With auxiliary diode D Group 1 is the first group, employing an integrated half-bridge MOSFET; the auxiliary switching transistor S bp2 With auxiliary diode D Group 2 is the second group, which uses an integrated half-bridge MOSFET.

9. The control strategy for a transient inductor voltage regulator with secondary-side energy recovery according to any one of claims 1-8, characterized in that, Includes the following steps: Step S1: The controller determines whether the load current has changed by detecting the output voltage fluctuation. If the output voltage and the rate of change of the output voltage change exceed the set value within the set time, it is determined that the load current has changed and proceeds to step S2. Step S2: After the controller detects a jump in the load current, it controls the auxiliary switching transistor. S bp1 and S bp2 Simultaneously launched; Step S3: The controller checks whether the output voltage has returned to a steady-state value. If it has, it controls the auxiliary switching transistor. S bp1 and S bp2 Shut down at the same time.

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