Optimal trajectory control method for load abrupt change of quasi-parallel resonant switched capacitor converter

Abstract

The invention provides an optimal trajectory control method for load abrupt change of a quasi-parallel resonant switched capacitor converter, and the quasi-parallel resonant switched capacitor converter comprises a resonant switched capacitor converter and a DC-DC converter. The method comprises the steps that state track control over the resonant switched capacitor converter and PI control over the DC-DC converter are executed, and working state switching is completed, specifically, the step of executing state track control over the resonant switched capacitor converter comprises the substeps that capacitor voltage and inductive current of a resonant unit in the resonant switched capacitor converter serve as state variables, and PI control over the DC-DC converter is executed; establishing a steady state trajectory model and a transient state trajectory model; and determining an optimal state trajectory according to the steady state trajectory model and the transient state trajectory model, and performing state trajectory control based on the determined optimal state trajectory. By adopting the scheme, the load transient response of the quasi-parallel resonant switched capacitor converter is optimized, and the dynamic response performance of the quasi-parallel resonant switched capacitor converter is effectively improved.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to an optimal trajectory control method for a quasi-parallel resonant switched capacitor converter with sudden load changes. Background Art

[0002] With the increasing demand for efficient and compact power supplies in many occasions such as data centers, electric vehicles, and DC civil buildings, DC-DC converters with high efficiency, high power density, and fast dynamic response have become the core of power supply design. They will play an indispensable role in promoting the advancement of modern power electronics technology and realizing green energy utilization.

[0003] The resonant switched capacitor converter mainly uses capacitors as energy storage conversion elements. The inductance is very small and plays a resonant role. It is easy to achieve soft switching of the switch tube. It has obvious advantages in operating efficiency, power density, weight, etc., but it is difficult to adjust the voltage in the zero current switching (ZCS) mode. DC-DC converters with inductors as the main energy storage conversion elements, such as Buck converters, are easy to achieve voltage regulation, but they are hard switching actions. The quasi-parallel structure of input series and output parallel can combine the advantages of the two types of converters, giving full play to the high efficiency and high power density characteristics of the resonant switched capacitor converter and the easy voltage regulation characteristics of the inductive DC-DC converter.

[0004] However, there is still a lack of in-depth research on the dynamic characteristics and control strategies of quasi-parallel resonant switched capacitor converters. Most of them still use traditional linear control methods such as proportional-integral (PI). When faced with large load mutations, the dynamic response performance is often poor, which is difficult to meet the actual requirements for fast response and high accuracy. Therefore, it is urgent to propose a new control method to optimize the load transient response of quasi-parallel resonant switched capacitor converters. Summary of the invention

[0005] The present application aims to solve one of the technical problems in the related art at least to some extent.

[0006] To this end, the first purpose of the present application is to propose an optimal trajectory control method for load mutation of a quasi-parallel resonant switched capacitor converter, which solves the technical problem that existing methods are difficult to meet the actual requirements for fast response and high precision, optimizes the load transient response of the quasi-parallel resonant switched capacitor converter, and effectively improves the dynamic response performance of the quasi-parallel resonant switched capacitor converter.

[0007] The second objective of the present application is to provide a quasi-parallel resonant switched capacitor converter.

[0008] To achieve the above-mentioned purpose, the first aspect of the present application proposes an optimal trajectory control method for a sudden load change of a quasi-parallel resonant switched capacitor converter. The quasi-parallel resonant switched capacitor converter includes a resonant switched capacitor converter and a DC-DC converter. The method is applied after a sudden load change. The method includes:

[0009] Execute state trajectory control of the resonant switched capacitor converter and PI control of the DC-DC converter to complete the working state switching, wherein the state trajectory control of the resonant switched capacitor converter is executed, including:

[0010] Taking the capacitor voltage and inductor current of the resonant unit in the resonant switched capacitor converter as state variables, a steady-state trajectory model and a transient state trajectory model are established;

[0011] The optimal state trajectory is determined according to the steady-state state trajectory model and the transient state trajectory model, and the state trajectory control is performed based on the determined optimal state trajectory.

[0012] The optimal trajectory control method for load mutation of a quasi-parallel resonant switched capacitor converter in an embodiment of the present application adopts optimal state trajectory control to quickly adjust the state variables of the resonant switched capacitor converter to the target state after detecting a significant change in load current. At the same time, combined with the PI control of the inductive DC-DC converter, the dynamic response speed of the system is improved and the output voltage fluctuation is reduced when the load mutates significantly, thereby achieving fast and smooth working state switching and ensuring the stability and reliability of the system.

[0013] Optionally, in one embodiment of the present application, the resonant switched capacitor converter is a multi-mode resonant switched capacitor converter MReSCC, the DC-DC converter is a Buck converter, the MReSCC includes a resonant unit 1 and a resonant unit 2, and the MReSCC includes a steady-state SS-I stage, a steady-state SS-II stage, a load switching transient TS-I stage, and a load switching transient TS-II stage during operation, the load switching transient is a sub-circuit state of the MReSCC under phase shifting or frequency modulation, and the MReSCC has at least one working mode;

[0014] The M-7:1 mode is a working mode with a step-down ratio Nr=7:1. The state trajectory control of MReSCC in the M-7:1 mode is performed, including:

[0015] Taking the capacitor voltage and inductor current of the resonant unit in the resonant switched capacitor converter as state variables, the steady-state trajectory model and transient state trajectory model under the M-7:1 mode are established;

[0016] The optimal state trajectory is determined according to the steady-state state trajectory model and the transient state trajectory model under the M-7:1 mode, and the state trajectory control is performed based on the determined optimal state trajectory.

[0017] Optionally, in one embodiment of the present application, a steady-state trajectory model under the M-7:1 mode is established, including:

[0018] The capacitor voltage v in the resonance unit 1 and the resonance unit 2 C1 , v C2 and the inductor current i L1 ,i L2 As the state variable, a target steady-state trajectory model is established;

[0019] Establish a steady-state trajectory model under the M-7:1 mode, including:

[0020] Write differential equations based on the working conditions of SS-I and SS-II stages under the M-7:1 mode and solve v C1N- i L1N and v C2N -i L2N The state trajectory equation is:

[0021]

[0022] Among them, the variables with subscript N are normalized variables, v CiN is the normalized capacitor voltage, v CiN =v Ci / V i1 ,i LiN is the normalized inductor current, i LiN =Z r i Li / V i1 , Z r is the characteristic impedance, Z r =(L r / C r ) 1 / 2 , L r is the inductance of the resonant unit, C r is the capacitance value of the resonant unit, and MReSCC is regarded as a turns ratio of N r The ideal DC transformer, V i1 is the input voltage of MReSCC, I o1 is the output current of MReSCC;

[0023] According to the state trajectory equation, the operation trajectory of the MReSCC on the phase plane is determined, and the operation trajectory includes the operation trajectories of the resonance unit 1 and the resonance unit 2 in the SS-I stage and the SS-II stage.

[0024] Optionally, in one embodiment of the present application, a transient state trajectory model under the M-7:1 mode is established, including:

[0025] In the TS-I stage, vC1N- i L1N and v C2N -i L2N The state trajectory equation is:

[0026]

[0027] Among them, v C1TS-IN 、v C2TS-IN 、i L1TS-IN 、i L2TS-IN C 1a / C 1b , C 2a / C 2b , L 1a / L 1b , L 2a / L 2b At the initial value of TS-I stage, C 1a , C 1b , L 1a , L 1b is the capacitance and inductance that constitute the resonance unit 1, C 2a , C 2b , L 2a , L 2b The capacitor and inductor constitute the resonance unit 2;

[0028] In the TS-II stage, v C1N- i L1N and v C2N -i L2N The state trajectory equation is:

[0029]

[0030] Among them, v C1TS-IIN 、i L1TS-IIN is the initial value in the TS-II stage.

[0031] Optionally, in one embodiment of the present application, determining the optimal state trajectory according to the steady-state trajectory model and the transient state trajectory model under the M-7:1 mode includes:

[0032] Calculate the switching points and duration of each operation phase when switching between light and heavy loads using the circuit states in the TS-I phase and the TS-II phase, and determine the optimal state trajectory based on the calculated switching points and duration.

[0033] Among them, the light-heavy load switching completed by the TS-I stage includes working condition 1 and working condition 2. Working condition 1 is to switch from heavy load to light load by using TS-I. The circuit state in working condition 1 is SS-II→TS-I→SS-II, and then it reaches a stable state under light load. Working condition 2 is to switch from light load to heavy load by using TS-I. The circuit state in working condition 2 is SS-I→TS-I→SS-I, and then it reaches a stable state under heavy load. The light-heavy load switching completed by using the TS-II stage includes working condition 3 and working condition 4. Working condition 3 is to switch from heavy load to light load by using TS-II. The circuit state in working condition 3 is SS-I→TS-II→SS-I, and then it reaches a stable state under light load. Working condition 4 is to switch from light load to heavy load by using TS-II. The circuit state in working condition 4 is SS-II→TS-II→SS-II, and then it reaches a stable state under heavy load.

[0034] Optionally, in one embodiment of the present application, in the TS-I stage, v C2N -i L2N The state trajectory of must intersect with its state trajectory under heavy load and light load, v C2N -i L2N The radius R of the state trajectory in the TS-I stage TS-IN The conditions for satisfying are:

[0035]

[0036] Among them, R SSLN Yes C2N -i L2N The radius of the state trajectory under light load steady state, R SSLN By the corresponding v C2N -i L2N The state trajectory equation is determined;

[0037] Switching point P HN and P LN satisfy;

[0038]

[0039] Among them, R SSN YesR SSLN and R SSHN Under light load, R SSN =R SSLN , R under heavy load SSN =R SSHN , R SSHN Yes C2N -i L2N The radius of the state trajectory in the heavy load steady state, R SSHN By the corresponding v C2N -i L2N The state trajectory equation is determined;

[0040] Switching point P HN and P LN The capacitor voltage v C2PHN and v C2PLN They are:

[0041]

[0042] Duration of TS-I phase t θ for:

[0043]

[0044] Among them, ω r is the resonant angular frequency, ω r =1 / (L r C r ) 1 / 2 ;

[0045] Duration t of SS-I stage or SS-II stage under heavy load pH for:

[0046]

[0047] Duration t of SS-I stage or SS-II under light load PL for:

[0048]

[0049] In the TS-II stage, v C2N -i L2N The state trajectory of must intersect with its state trajectory under heavy load and light load, v C2N -i L2N The radius R of the state trajectory in the TS-II stage TS-IIN The conditions for satisfying are:

[0050]

[0051] Switching point Q HN and Q LN satisfy:

[0052]

[0053] Switching point Q HN and Q LN The capacitor voltage v C2QHN and v C2QLN They are:

[0054]

[0055] Duration of TS-I phase t γ for:

[0056]

[0057] Duration t of SS-I stage or SS-II stage under heavy load QH for:

[0058]

[0059] Duration t of SS-I stage or SS-II under light load QL for:

[0060]

[0061] Among them, T r is the resonant period, T r =2π(L r C r ) 1 / 2 .

[0062] Optionally, in one embodiment of the present application, performing state trajectory control based on the determined optimal state trajectory includes:

[0063] Execute single-step optimal state trajectory control and gradually restore the PWM of each switch tube to a stable state.

[0064] Optionally, in one embodiment of the present application, performing optimal state trajectory control under loading conditions includes:

[0065] Step S1: perform ADC sampling, PI calculation and first optimal state trajectory calculation to determine the initial value of each duration variable;

[0066] Step S2: Repeat ADC sampling, PI calculation and optimal state trajectory calculation until t PH =t QH =T r / 2 and t θ =t γ =0, at each state trajectory calculation, the initial value of each duration variable is increased or decreased. During the execution of Condition 2 and Condition 4, only the state trajectory time calculation and PWM update are performed, and ADC sampling and PI calculation are not performed. After the execution of Condition 2 or Condition 4, ADC sampling and PI update are performed.

[0067] To achieve the above objectives, a second embodiment of the present invention proposes a quasi-parallel resonant switched capacitor converter, which realizes optimal control through the above-mentioned optimal trajectory control method for load mutation of the quasi-parallel resonant switched capacitor converter when the load suddenly changes.

[0068] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0070] Figure 1 A schematic flow chart of an optimal trajectory control method for a sudden load change of a quasi-parallel resonant switched capacitor converter provided in the first embodiment of the present application;

[0071] Figure 2 A topology diagram of a quasi-parallel resonant switched capacitor converter according to an embodiment of the present application;

[0072] Figure 3 A typical waveform diagram of the isolation unit of an embodiment of the present application;

[0073] Figure 4 This is a working state diagram of the isolation unit of an embodiment of the present application;

[0074] Figure 5 This is a typical waveform of MReSCC and its working state diagram of an embodiment of the present application;

[0075] Figure 6 It is a state trajectory diagram of the MReSCC of the embodiment of the present application under steady-state SS-I and SS-II;

[0076] Figure 7 A circuit state diagram of the MReSCC in the transient state TS-I according to an embodiment of the present application;

[0077] Figure 8 This is a state trajectory diagram of the MReSCC in the transient state TS-I of an embodiment of the present application;

[0078] Fig. 9 A circuit state diagram of the MReSCC in the transient state TS-II of an embodiment of the present application;

[0079] Fig.10 This is a state trajectory diagram of the MReSCC in the transient state TS-II of an embodiment of the present application;

[0080] Fig.11 This is a state trajectory diagram of the MReSCC when switching between light and heavy loads according to an embodiment of the present application;

[0081] Fig.12 PWM sequence and inductor current diagram when the MReSCC switches between light and heavy loads according to an embodiment of the present application;

[0082] Fig.13 A PWM sequence for performing optimal state trajectory control under loading conditions in an embodiment of the present application;

[0083] Fig.14 These are the load addition and reduction test results before and after optimization of the optimal state trajectory control of an embodiment of the present application. DETAILED DESCRIPTION

[0084] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0085] The following describes the optimal trajectory control method and device for load mutation of a quasi-parallel resonant switched capacitor converter according to an embodiment of the present application with reference to the accompanying drawings.

[0086] Figure 1 A flow chart of an optimal trajectory control method for a sudden load change of a quasi-parallel resonant switched capacitor converter provided in Example 1 of the present application, the quasi-parallel resonant switched capacitor converter includes a resonant switched capacitor converter and a DC-DC converter, and the method is applied after a sudden load change.

[0087] like Figure 1 As shown, the optimal trajectory control method for the sudden load change of the quasi-parallel resonant switched capacitor converter includes the following steps:

[0088] Step 101, executing state trajectory control of the resonant switched capacitor converter and PI control of the DC-DC converter to complete the working state switching, wherein executing the state trajectory control of the resonant switched capacitor converter includes:

[0089] Taking the capacitor voltage and inductor current of the resonant unit in the resonant switched capacitor converter as state variables, a steady-state trajectory model and a transient state trajectory model are established;

[0090] The optimal state trajectory is determined according to the steady-state state trajectory model and the transient state trajectory model, and the state trajectory control is performed based on the determined optimal state trajectory.

[0091] In this embodiment, the quasi-parallel resonant switched capacitor converter (QPReSCC) topology is as follows: Figure 2As shown in the figure, it mainly includes three parts: isolation unit, multi-mode resonant switched capacitor converter (Multi-mode Resonant Switched Capacitor Converter, MReSCC) and Buck converter. The isolation unit is used to avoid short circuit between the input and output of non-isolated MReSCC and Buck converter; MReSCC is used to soft switch and efficiently transmit most of the power; Buck converter is used to adjust the output voltage.

[0092] Capacitor C i1 and C i2 are the input capacitance of MReSCC and Buck, respectively, and Co is the common output capacitance. The QPReSCC equivalent is composed of MReSCC and Buck converter connected in series on the input side and in parallel on the output side, where the voltage and current of MReSCC and Buck converter are mutually restricted, but their operating states are independent of each other. The working state of the isolation unit is closely related to MReSCC. Figure 3 , Figure 4 The typical waveform of the isolation unit and its working state diagram are as follows: Figure 3 , Figure 4 As shown, the switch tube S i1 and S i3 The actions of S2 and S1 in MReSCC are the same, S i2 With S i1 Turn on at the same time but turn off early.

[0093] Capacitor C ia , C ib 、Inductance L ia , L ib , and switch tube S ia , S ib , S iab The MReSCC contains two resonant units, namely unit 1 and unit 2. Capacitor C 1a , C 1b , C 2a , C 2b The capacitance value is the same, C 1a =C 1b =C 2a =C 2b =C r , the capacitor voltage satisfies v C1a =v C1b =v C1 , v C2a =v C2b =v C2 ; Inductance L 1a , L 1b , L 2a and L 2bThe inductance value is the same, L 1a =L 1b =L 2a =L 2b =L r , the inductor current satisfies i L1a =i L1b =i L1 ,i L2a =i L2b =i L2 In addition, the switches S1, S2 and S3 are the main switches, and the actions of the other switches are the same or complementary. Generally, S1 and S3 act synchronously and complement S2, and the switching frequency f s With the resonant frequency f r (f r =1 / 2π(L r C r ) 1 / 2 The duty cycle is 1 / 2, and there are two working states: steady state I and steady state II, referred to as SS-I and SS-II, respectively. Each switch tube achieves ZCS. ia / L ia With C ib / L ib The series and parallel state of S ia , S ib and S iab The switch state can be changed flexibly, and MReSCC has multiple working modes. Figure 5 Shows one of the step-down ratios N r =Typical waveform and working status under 7:1 working mode, referred to as M-7:1.

[0094] MReSCC is regarded as a turn ratio of N r An ideal DC transformer with an input voltage V i1 With output voltage V o The relationship is expressed as:

[0095] V i1 =N r V o

[0096] Buck converter input voltage V i2 With output voltage V o The relationship is expressed as:

[0097]

[0098] Among them, D b is the switch tube S in the Buck converter b duty cycle.

[0099] The input voltage V of QPReSCC i With output voltage V o The relationship is expressed as:

[0100]

[0101] Among them, M and N represent the voltage gain and step-down ratio of QPReSCC respectively, and the two are reciprocals of each other.

[0102] The output current of MReSCC is I o1 The output current I of the Buck converter o2 The ratio is the ratio of the two input voltages, that is:

[0103]

[0104] In this embodiment, the QPReSCC is in steady state, the MReSCC works in an open loop, and the PI controller of the Buck converter controls its duty cycle to eliminate the steady-state error of the output voltage. When the QPReSCC has a small load mutation, it is sufficient to achieve a good output voltage response only through the PI controller of the Buck converter, but under the condition of a large load mutation, its output voltage fluctuates greatly, the adjustment time is long, and the overall load transient response is poor. Therefore, in order to solve the problem of poor transient response of the QPReSCC under the condition of large load mutation, the optimal state trajectory control method of the QPReSCC fast load mutation is applied. This method detects the load state change of the QPReSCC, adopts the optimal state trajectory control to quickly adjust the state variable of the MReSCC to a stable state, and combines the PI controller of the Buck converter to achieve the fast and stable switching of the QPReSCC under large load mutations such as no load or light load and full load or heavy load. This embodiment takes the M-7:1 mode as an example to illustrate the specific technical solution.

[0105] 1) Steady-state trajectory analysis: Take the capacitor voltage v in unit 1 and unit 2 as C1 , v C2 and the inductor current i L1 ,i L2 The steady-state trajectory model of MReSCC is established based on the state variables. Specifically, the differential equations are written according to the working states of MReSCC in the SS-I and SS-II stages under the M-7:1 mode, and v is solved. C1N- i L1N and v C2N- i L2N The state trajectory equation is:

[0106]

[0107] Among them, v CiN is the normalized capacitor voltage, v CiN=v Ci / V i1 ,i LiN is the normalized inductor current, i LiN =Z r i Li / V i1 , Z r is the characteristic impedance, Z r =(L r / C r ) 1 / 2 In this embodiment, variables with a subscript of N all represent normalized variables.

[0108] Then, according to the state trajectory equation, the running trajectory of MReSCC on the phase plane is drawn. The running trajectories of the state variables in unit 1 and unit 2 in the steady-state SS-I and SS-II stages are semicircles with (3 / 7, 0) and (1 / 7, 0) as the center, respectively, as shown in Figure 6 As shown. Under different loads, v CiN- i LiN The state trajectories have the same center, different radii, and v C2N- i L2N The radius of the state trajectory is always v C1N- i L1N twice as much.

[0109] 2) Transient state trajectory analysis: It is difficult to achieve fast and smooth switching between different loads by using only two circuit states of SS-I and SS-II stages. This embodiment proposes to use the sub-circuit state of MReSCC under phase shift or frequency modulation as the switching transient stage to achieve fast and smooth switching between two different load steady states.

[0110] Figure 7 It is the circuit state of the load switching transient stage I (abbreviated as TS-I). In the TS-I stage, S1, S3, S i3 , S 1ab , S 2a , S 2b , S m2 and S m3 In unit 1, C 1a and L 1a With C 1b and L 1b connected in series and with the input voltage V i1 Through S1, S i3 and S m2 In Unit 2, C 2a and L 2a With C 2b and L 2b connected in parallel and through S3 and Sm3 Forming a circuit loop. TS-I Phase v C1N- i L1N and v C2N- i L2N The state trajectory equation is:

[0111]

[0112] Among them, v C1TS-IN , v C2TS-IN ,i L1TS-IN and i L2TS-IN C 1a / C 1b , C 2a / C 2b , L 1a / L 1b and L 2a / L 2b Initial value in TS-I phase.

[0113] According to the above formula, v is plotted in the TS-I stage. C1N- i L1N and v C2N- i L2N The state trajectories are circles with (1 / 2,0) and (0,0) as the centers, such as Figure 8 The radius of each state trajectory depends on the initial value of the resonant branch.

[0114] Fig. 9 It is the circuit state of the load switching transient stage II (abbreviated as TS-II). In the TS-II stage, S2, S 1a , S 1b , S 2ab , S m1 and S m4 In unit 1, C 1a and L 1a With C 1b and L 1b connected in parallel. In unit 2, C 2a and L 2a With C 2b and L 2b The resonant branches in unit 1 and unit 2 are connected in series through S2, S m1 , and S m4 Forming a circuit loop. TS-II Phase v C1N- i L1N and v C2N- i L2N The state trajectory equation is:

[0115]

[0116] Among them, v C1TS-IIN and i L1TS-IIN C 1a / C 1b and L 1a / L 1b Initial value in TS-II stage.

[0117] According to the above formula, v is plotted in the TS-II stage. C1N- i L1N and v C2N- i L2N The state trajectories are circles with (2 / 5,0) and (0,0) as the centers, such as Fig.10 The radius of each state trajectory depends on the initial value of the resonant branch.

[0118] 3) Design of optimal state trajectory when switching between light and heavy loads: The circuit states under TS-I and TS-II can be used to complete fast and smooth switching between light and heavy loads, which is specifically divided into four working conditions, such as Fig.11 shown. Fig.12 is the PWM sequence and inductor current under the corresponding working condition. This step is mainly based on v CiN- i LiN The state trajectory calculates the switching points and duration of each operating phase. C2N- i L2N With v C1N- i L1N The state trajectory of is always in the opposite direction, and the radius is in multiple relationship, so one of them is used for derivation and calculation. This embodiment is based on v C2N- i L2N The state trajectory is derived to calculate the switching points and duration.

[0119] There are two working conditions for switching between heavy load and light load using TS-I, namely Fig.11 The working conditions 1 and 2 are shown. Working condition 1 is to switch from heavy load to light load by using TS-I, the circuit state is SS-II→TS-I→SS-II, and then reach a stable state under light load. Working condition 2 is to switch from light load to heavy load by using TS-I, the circuit state is SS-I→TS-I→SS-I, and then reach a stable state under heavy load.

[0120] TS-I stage lower v C2N- i L2N The state trajectory of must intersect with its state trajectory under heavy load and light load, so v C2N- i L2N The radius R of the state trajectory in the TS-I stage TS-IN Need to meet:

[0121]

[0122] Among them, R SSLN Yes C2N- i L2N The radius of the state trajectory under light load steady state can be obtained from the v obtained in the steady state trajectory analysis stage. C1N- i L1N and v C2N- i L2N The state trajectory equation is obtained.

[0123] Switching point P HN and P LN The following relations are satisfied:

[0124]

[0125] Among them, R SSN YesR SSLN and R SSHN Under light load, R SSN =R SSLN , R under heavy load SSN =R SSHN , R SSHN Yes C2N- i L2N The radius of the state trajectory in the heavy-load steady state can be obtained from the v obtained in the steady-state state trajectory analysis stage. C1N- i L1N and v C2N- i L2N The state trajectory equation is obtained.

[0126] According to the above formula, the switching point P HN and P LN The capacitor voltage v C2PHN and v C2PLN The derivations are:

[0127]

[0128] Duration of TS-I phase t θ for:

[0129]

[0130] where ω r is the resonant angular frequency, ω r =1 / (L r C r ) 1 / 2 .

[0131] Duration t of SS-I stage or SS-II stage under heavy load PH for:

[0132]

[0133] Duration t of SS-I stage or SS-II stage under light load PL for:

[0134]

[0135] The switching between heavy load and light load using TS-II is also divided into two working conditions, namely Fig.11 The working conditions 3 and 4 are shown. Working condition 3 is to switch from heavy load to light load by using TS-II, the circuit state is SS-I→TS-II→SS-I, and then reach a stable state under light load. Working condition 4 is to switch from light load to heavy load by using TS-II, the circuit state is SS-II→TS-II→SS-II, and then reach a stable state under heavy load.

[0136] Similarly, in the TS-II stage, v C2N- i L2N The state trajectory of must intersect with its state trajectory under heavy load and light load, so v C2N- i L2N The radius R of the state trajectory in the TS-II stage TS-IIN Need to meet:

[0137]

[0138] Switching point Q HN and Q LN The following relations are satisfied:

[0139]

[0140] According to the above formula, the switching point Q HN and Q LN The capacitor voltage v C2QHN and v C2QLN The derivations are:

[0141]

[0142] Duration of TS-II phase t γ for:

[0143]

[0144] Duration t of SS-I stage or SS-II stage under heavy load QH for:

[0145]

[0146] Duration t of SS-I stage or SS-II stage under light load QL for:

[0147]

[0148] 4) Implementation of the optimal state trajectory control method: In order to effectively achieve fast load transient response, this embodiment proposes that after executing Fig.11 After the single-step optimal state trajectory shown, the PWM of each switch tube is gradually restored to a stable state.

[0149] Fig.13 is the PWM sequence for executing the optimal state trajectory control under loading conditions. When the load current increases and the change is greater than the threshold, ADC sampling, PI calculation and the first optimal state trajectory calculation are performed, where the load current threshold can be selected according to the load transient response control effect of the PI controller in the Buck converter. To simplify the calculation, v C2N- i L2N The radius of the state trajectory in the TS-I and TS-II stages can be selected as R TS-IN =1 / 7+R SLN and R TS-IIN =2 / 35+R SLN , omitting t PL and t QL Calculation of t θ ,t PH ,t γ and t QH The initial value of is obtained from the first state trajectory calculation, and each subsequent state trajectory calculation is gradually increased or decreased based on the initial value of each duration variable. During the execution of Condition 2 and Condition 4, only the state trajectory time calculation and PWM update are performed, and ADC sampling and PI calculation are not performed. After the execution of Condition 2 or Condition 4, ADC sampling and PI update are performed once to effectively control the output voltage. Repeat the above steps until t PH =t QH =T r / 2 and t θ =t γ = 0. The execution steps of the optimal state trajectory control under load reduction conditions are Fig.10 Similarly, it mainly involves working conditions 1 and 3.

[0150] The design, calculation and execution methods of the optimal state trajectory control in 1) to 4) above can not only be extended to other operating modes of MReSCC, but can also be applied to other quasi-parallel resonant switched capacitor converters.

[0151] The optimal state trajectory control method for the quasi-parallel resonant switched capacitor converter proposed in this embodiment was verified on a rated 48V-5V / 100 experimental prototype. Fig.14 shows the load current I oWhen the voltage changes from 8A to 20A to 8A, the output voltage dynamic response performance before and after the optimal state trajectory control is adopted. It can be seen that after the optimal state trajectory control is adopted, the inductor current I L2a Faster switching from one steady state to another with no inrush current facilitates faster regulation of the output voltage V o Especially under load reduction conditions, through optimal state trajectory control, not only the output voltage fluctuation ΔV o The adjustment time Δt is reduced by 58.3% compared with that before optimization. Experiments show that the optimal state trajectory control method proposed in this embodiment can improve the dynamic response performance of the output voltage when a quasi-parallel resonant switched capacitor converter undergoes a large load change.

[0152] In order to implement the above embodiment, the present application also proposes a quasi-parallel resonant switched capacitor converter, which achieves optimal control through the above-mentioned optimal control method for load mutation of the quasi-parallel resonant switched capacitor converter when the load suddenly changes.

[0153] It should be noted that the above explanation of the optimal trajectory control method embodiment for sudden load changes of a quasi-parallel resonant switched capacitor converter is also applicable to the quasi-parallel resonant switched capacitor converter of this embodiment, and will not be repeated here.

[0154] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0155] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0156] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0157] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0158] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0159] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0160] In addition, each functional unit in each embodiment of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0161] The storage medium mentioned above may be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application. A person of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. An optimal trajectory control method for a quasi-parallel resonant switched capacitor converter with a sudden load change, characterized in that: The quasi-parallel resonant switched capacitor converter includes a resonant switched capacitor converter and a DC-DC converter. The method is applied after a sudden load change. The method includes: Executing the state trajectory control of the resonant switched capacitor converter and the PI control of the DC-DC converter to complete the working state switching, wherein executing the state trajectory control of the resonant switched capacitor converter includes: Taking the capacitor voltage and inductor current of the resonant unit in the resonant switched capacitor converter as state variables, a steady-state trajectory model and a transient state trajectory model are established; An optimal state trajectory is determined according to the steady-state state trajectory model and the transient state trajectory model, and state trajectory control is performed based on the determined optimal state trajectory.

2. The method according to claim 1, characterized in that The resonant switched capacitor converter is a multi-mode resonant switched capacitor converter MReSCC, the DC-DC converter is a Buck converter, the MReSCC includes a resonant unit 1 and a resonant unit 2, and the MReSCC includes a steady-state SS-I stage, a steady-state SS-II stage, a load switching transient TS-I stage, and a load switching transient TS-II stage during operation, the load switching transient is a sub-circuit state of the MReSCC under phase shift or frequency modulation, and the MReSCC has at least one working mode; M-7:1 mode is step-down ratio N r =7:1 working mode, execute the state trajectory control of MReSCC in M-7:1 mode, including: Taking the capacitor voltage and inductor current of the resonant unit in the resonant switched capacitor converter as state variables, the steady-state trajectory model and transient state trajectory model under the M-7:1 mode are established; The optimal state trajectory is determined according to the steady-state state trajectory model and the transient state trajectory model under the M-7:1 mode, and the state trajectory control is performed based on the determined optimal state trajectory.

3. The method according to claim 2, characterized in that Establish a steady-state trajectory model under the M-7:1 mode, including: The capacitor voltage v in the resonance unit 1 and the resonance unit 2 C1 , v C2 and the inductor current i L1 ,i L2 As the state variable, a target steady-state trajectory model is established; Establish a steady-state trajectory model under the M-7:1 mode, including: Write differential equations based on the working conditions of SS-I and SS-II stages under the M-7:1 mode and solve v C1N- i L1N and v C2N -i L2N The state trajectory equation is: Among them, the variables with subscript N are normalized variables, v CiN is the normalized capacitor voltage, v CiN =v ci / V i1 ,i LiN is the normalized inductor current, i LiN =Z r i Li / V i1 , Z r is the characteristic impedance, Z r =(L r / C e ) 1 / 2 , L r is the inductance of the resonant unit, C r is the capacitance value of the resonant unit, and MReSCC is regarded as a turns ratio of N r The ideal DC transformer, V i1 is the input voltage of MReSCC, I o1 is the output current of MReSCC; According to the state trajectory equation, the operation trajectory of the MReSCC on the phase plane is determined, and the operation trajectory includes the operation trajectories of the resonance unit 1 and the resonance unit 2 in the SS-I stage and the SS-II stage.

4. The method according to claim 2, characterized in that Establish the transient state trajectory model under the M-7:1 mode, including: In the TS-I stage, v C1N- i L1N and v C2N -i L2N The state trajectory equation is: Among them, v C1TS-IN 、v C2TS-IN 、i L1TS-IN 、i L2TS-IN C 1a / C 1b , C 2a / C 2b , L 1a / L 1b , L 2a / L 2b At the initial value of TS-I stage, C 1a , C 1b , L 1a , L 1b is the capacitance and inductance that constitute the resonance unit 1, C 2a , C 2b , L 2a , L 2b The capacitor and inductor constitute the resonance unit 2; In the TS-II stage, v C1N- i L1N and v C2N -i L2N The state trajectory equation is: Among them, v C1TS-IIN 、i L1TS-IIN is the initial value in the TS-II stage.

5. The method according to any one of claims 3-4, characterized in that: The optimal state trajectory is determined based on the steady-state trajectory model and transient state trajectory model under the M-7:1 mode, including: Calculate the switching points and duration of each operation phase when switching between light and heavy loads using the circuit states in the TS-I phase and the TS-II phase, and determine the optimal state trajectory based on the calculated switching points and duration. Among them, the light-heavy load switching completed by the TS-I stage includes working condition 1 and working condition 2. Working condition 1 is to switch from heavy load to light load by using TS-I. The circuit state in working condition 1 is SS-II→TS-I→SS-II, and then it reaches a stable state under light load. Working condition 2 is to switch from light load to heavy load by using TS-I. The circuit state in working condition 2 is SS-I→TS-I→SS-I, and then it reaches a stable state under heavy load. The light-heavy load switching completed by using the TS-II stage includes working condition 3 and working condition 4. Working condition 3 is to switch from heavy load to light load by using TS-II. The circuit state in working condition 3 is SS-I→TS-II→SS-I, and then it reaches a stable state under light load. Working condition 4 is to switch from light load to heavy load by using TS-II. The circuit state in working condition 4 is SS-II→TS-II→SS-II, and then it reaches a stable state under heavy load.

6. The method according to claim 5, characterized in that In the TS-I stage, v C2N -i L2N The state trajectory of must intersect with its state trajectory under heavy load and light load, v C2N -i L2N The radius R of the state trajectory in the TS-I stage TS-IN The satisfying conditions are: Among them, R SSLN Yes C2N -i L2N The radius of the state trajectory under light load steady state, R SSLN By the corresponding v C2N -i L2N The state trajectory equation is determined; Switching point P HN and P LN satisfy; Among them, R SSN YesR SSLN and R SSHN Under light load, R SSN =R SSLN , R under heavy load SSN =R SSHN , R SSHN Yes C2N -i L2N The radius of the state trajectory in the heavy load steady state, R SSHN By the corresponding v C2N -i L2N The state trajectory equation is determined; Switching point P HN and R LN The capacitor voltage v C2PHN and v C2PLN They are: Duration of TS-I phase t θ for: Among them, ω r is the resonant angular frequency, ω r =1 / (L r C r ) 1 / 2 ; Duration t of SS-I stage or SS-II stage under heavy load PH for: Duration t of SS-I stage or SS-II under light load PL for: In the TS-II stage, v C2N -i L2N The state trajectory of must intersect with its state trajectory under heavy load and light load, v C2N -i L2N The radius R of the state trajectory in the TS-II stage TS-IIN The conditions for satisfying are: Switching point Q HN and Q LN satisfy: Switching point Q HN and Q LN The capacitor voltage v c2QHN and v C2QLN They are: Duration of TS-I phase t γ for: Duration t of SS-I stage or SS-II stage under heavy load QH for: Duration t of SS-I stage or SS-II under light load QL for: Among them, T r is the resonant period, T r =2π(L r C r ) 1 / 2 .

7. The method according to claim 6, characterized in that The performing state trajectory control based on the determined optimal state trajectory includes: Execute single-step optimal state trajectory control and gradually restore the PWM of each switch tube to a stable state.

8. The method according to claim 7, characterized in that Perform optimal state trajectory control under loading conditions, including: Step S1: perform ADC sampling, PI calculation and first optimal state trajectory calculation to determine the initial value of each duration variable; Step S2: Repeat ADC sampling, PI calculation and optimal state trajectory calculation until t PH =t QH =T r / 2 and t θ =t γ =0, at each state trajectory calculation, the initial value of each duration variable is increased or decreased. During the execution of Condition 2 and Condition 4, only the state trajectory time calculation and PWM update are performed, and ADC sampling and PI calculation are not performed. After the execution of Condition 2 or Condition 4, ADC sampling and PI update are performed.

9. A quasi-parallel resonant switched capacitor converter, characterized in that: The quasi-parallel resonant switched capacitor converter achieves optimal control when a load mutation occurs through the method described in claims 1-8.

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