Bidirectional DC / DC Converter Based on Disturbance Observation Predictive Control

Abstract

The present invention belongs to the technical field of power electronic converter control, and discloses a bidirectional DC / DC conversion device based on disturbance observation predictive control. The bidirectional DC / DC conversion method based on disturbance observation predictive control includes: establishing an inner and outer loop predictive control model of the converter working in Boost mode and Buck mode according to the mathematical model calculation of the circuit, designing a Lumberg disturbance observer in the forward and reverse direction mode and compensating it online into the predictive model, adopting error feedback and observed disturbance feedforward, realizing the model predictive control of the continuous set based on the deadbeat method, obtaining the optimal control quantity in each working mode, and sending the optimal control duty cycle to the carrier phase shift PWM module to obtain the switching pulse signal. The present invention retains the advantage of fast dynamic response speed of traditional model predictive control, and can accurately and quickly track the given in the presence of external disturbances and internal model mismatch.

Description

Technical Field

[0001] The invention belongs to the technical field of power electronic converter control, and in particular relates to a bidirectional DC / DC converter device based on disturbance observation predictive control. Background Art

[0002] In recent years, DC-DC converters have been widely used in fuel cell vehicle power systems, photovoltaic power generation, UPS, energy storage systems and other fields due to their energy conversion and regulation functions. Among them, the interleaved parallel bidirectional half-bridge DC / DC converter, as an important component of the converter, is an important bridge connecting the DC bus and the energy storage medium, and has the advantages of reducing the current stress and switching loss of each phase switch device. The use of an interleaved parallel topology can achieve a higher frequency output and reduce the switching frequency of each phase. For batteries and photovoltaic array batteries that require low input current ripple and high dynamic response, the use of interleaved parallel technology is a good solution.

[0003] Among the various control methods of traditional interleaved parallel bidirectional half-bridge DC / DC converters, dual closed-loop PI control is the most mature. However, the traditional dual closed-loop control adopts proportional-integral (PI) control, which has slow response time, long adjustment time, and difficult adjustment of multiple PI controller parameters, which greatly limits the dynamic performance. Model predictive control is widely used in motor drive and other related fields due to its fast dynamic response speed and flexible control objectives. If both the inner and outer loops adopt the MPC control strategy, the dynamic response speed of the system will be greatly increased. However, the control performance of MPC depends largely on the accuracy of system modeling. The change of circuit parameters will cause the nominal value of the control system parameter to not match the actual value of the system parameter, and the converter operating point will be far away from the nominal value, which will affect the stability and robustness of the control system. Due to the change of working conditions, the system is easily disturbed, such as the disturbance of load resistance, the fluctuation of input and output voltage, and the parameter mismatch caused by the non-ideality of inductance and capacitance, which may lead to the instability of the converter and static error.

[0004] Therefore, there is an urgent need for a new bidirectional DC / DC converter based on disturbance observation and predictive control to make up for the defects of the prior art.

[0005] Through the above analysis, the problems and defects of the prior art are as follows:

[0006] (1) Among the various control methods of traditional interleaved parallel bidirectional half-bridge DC / DC converters, the dual closed-loop control adopts proportional-integral (PI) control, which has slow response time and long adjustment time. In addition, it is difficult to adjust the parameters of multiple PI controllers, and the dynamic performance is greatly limited.

[0007] (2) The control performance of MPC depends largely on the accuracy of system modeling. Changes in circuit parameters will cause the nominal values ​​of the control system parameters to not match the actual system parameter values, and the converter operating point will be far away from the nominal value, which will in turn affect the stability and robustness of the control system.

[0008] (3) Due to changes in operating conditions, the system is susceptible to interference, such as disturbances in load resistance, fluctuations in input and output voltages, and parameter mismatches caused by the non-ideality of inductance and capacitance, which may lead to converter instability and the output cannot accurately and quickly track the reference, resulting in static errors.

[0009] The difficulty of solving the above problems and defects is as follows: The difficulty of solving the above problems is mainly reflected in how to achieve fast dynamic response of DC / DC converter, accurate steady-state tracking, and strong anti-interference performance. Relying on existing technology can achieve fast dynamic response or good anti-interference ability, but it is difficult to take into account multiple control objectives at the same time, and does not consider the impact of multiple disturbance items on steady-state static error.

[0010] The significance of solving the above problems and defects is that as one of the important components of fuel cell vehicle power system, photovoltaic power generation, UPS, energy storage system, etc., the performance of DC-DC converter is particularly important for the entire system and will directly affect the stability and reliability of the system. The solution to the above problems and defects not only enables the control system of DC-DC converter to have the advantages of traditional model predictive control method, but also improves the traditional method, further improves the stability and rapidity of the system, and has important application significance for improving the dynamic performance of the converter. Summary of the invention

[0011] In view of the problems existing in the prior art, the present invention provides a bidirectional DC / DC conversion device based on disturbance observation predictive control, and in particular relates to a bidirectional DC / DC conversion device based on disturbance observation predictive control based on online disturbance observation compensation, aiming to solve the problem in traditional model predictive control methods that the converter is unstable due to external disturbances and internal model mismatch, and the output cannot accurately and quickly track the reference.

[0012] The present invention is implemented as follows: a bidirectional DC / DC conversion method based on disturbance observation predictive control, the bidirectional DC / DC conversion method based on disturbance observation predictive control comprising:

[0013] According to the mathematical model of the circuit, the inner and outer loop predictive control models of the converter working in Boost mode and Buck mode are established. The Lumberg disturbance observer in the forward and reverse direction modes is designed and compensated online to the predictive model. The error feedback and observed disturbance feedforward are used to realize the model predictive control of the continuous set based on the deadbeat method. The optimal control quantity in each working mode is obtained, and the optimal control duty cycle is sent to the carrier phase-shift PWM module CPS-PWM to obtain the switching pulse signal.

[0014] Furthermore, the bidirectional DC / DC conversion method based on disturbance observation predictive control comprises the following steps:

[0015] Step 1: determine the state variables, state equations and parameters of the bidirectional half-bridge DC / DC converter, and establish a discrete mathematical model of the converter; in the current control mode, the outer loop is based on the power balance principle, and the inner loop adopts the model predictive control method to improve the dynamic response speed of the overall control system;

[0016] Step 2, according to the discrete mathematical model of the system, the Lumberg disturbance observer of the bidirectional half-bridge DC / DC converter in the forward and reverse working modes, i.e., the three-phase interleaved parallel Boost and Buck modes, is designed respectively;

[0017] Step 3: According to the system mathematical model and the Lumberg disturbance observer, the observed state variables are compensated online into the prediction model, and the error feedback and observed disturbance feedforward control methods are adopted, combined with the continuous set model predictive control based on the deadbeat method, to adjust the optimal control quantity output by the converter in the forward and reverse working modes respectively;

[0018] Step 4: Send the optimal control duty cycle to the CPS-PWM module to obtain the pulse signal of the three-phase switch tube.

[0019] Further, in step 1, the state variables, state equations and parameters of the bidirectional half-bridge DC / DC converter are determined, and a discrete mathematical model of the converter is established; in the current control mode, the outer loop is based on the power balance principle, and the inner loop adopts a model predictive control method to improve the dynamic response speed of the overall control system, including:

[0020] (1) Establishing the mathematical model of the converter: When the converter works in the Boost mode, the model is built based on the switch on and off. Based on Kirchhoff's law and the state space averaging method, the continuous time mathematical model of the three-phase interleaved parallel Boost converter is obtained:

[0021]

[0022] Among them, u i (t) is the system input, V in 、V oare the input and output voltages, R o is the equivalent load resistance, C f is the output capacitance, L i (i=1,2,3) is the inductance of each phase, i Li (i=1,2,3) is the inductor current of each phase, R Li (i=1,2,3) is the equivalent series resistance of each phase inductor.

[0023] Using forward Euler discretization, the discrete-time mathematical model of the converter is obtained:

[0024]

[0025] Among them, T s is the sampling time, v=V in , A, B, C, E are system coefficient matrices:

[0026]

[0027] x=[i L1 i L2 i L3 V o ] T .

[0028] The outer loop is based on the power balance principle: According to the model instantaneous power balance theory, the relationship between input and output and the total inductor current reference value is obtained:

[0029]

[0030] The current reference value of each phase is required to be 1 / 3 of the total reference value to achieve current sharing. The inductor current reference value of each phase is obtained as follows:

[0031]

[0032] The inner loop adopts the model predictive control method: Assuming that the input and output voltages remain constant within a sampling period, the inductor current changes linearly. According to the discrete mathematical model, the inductor current value at time k+1 is predicted from time k:

[0033]

[0034] The predictive control cost function is obtained:

[0035] The cost function is respectively applied to the control quantity u i (k) Find the partial derivative and set the derivative equal to 0 to determine the value of the control quantity that minimizes the cost function:

[0036] calculate get: It is output as the control quantity to the CPS-PWM module for modulation.

[0037] (2) When the converter works in Buck mode, the model is built based on the switch on and off. Based on Kirchhoff's law and state space averaging method, the continuous time mathematical model of the three-phase interleaved parallel Buck converter is obtained:

[0038]

[0039] The discrete-time mathematical model of the converter is obtained:

[0040] Among them, T s is the sampling time, A b ,B b , C is the system coefficient matrix:

[0041] x=[i L1 i L2 i L3 V o ] T .

[0042] According to Kirchhoff's current theory:

[0043] Considering current sharing, the reference value of the inductor current of each phase is:

[0044] The inner loop adopts the model predictive control method, and the inductor current value at time k+1 is predicted from time k:

[0045]

[0046] The cost function is obtained:

[0047]

[0048] calculate get:

[0049] It is output as the control quantity to the CPS-PWM module for modulation.

[0050] Further, in step 2, the Lumberg disturbance observer of the bidirectional half-bridge DC / DC converter in the forward and reverse working modes, i.e., three-phase interleaved parallel Boost and Buck modes, is designed respectively according to the system discrete mathematical model, including:

[0051] A Romberg disturbance observer is designed and the observed state variables are compensated online into the prediction model.

[0052] (1) For Boost working mode:

[0053] Lumped disturbance observation: According to the discrete mathematical model in step 1, the lumped disturbance term is defined as:

[0054]

[0055] Taking the disturbance term and the inductor current as state variables, the discrete mathematical model of the system is rewritten as:

[0056]

[0057] Among them, X di (t) = [i Li D i ] T , C d =[1 0], v d =V o .

[0058] The disturbance observer is designed as:

[0059]

[0060] Where H = [H 1 H 2 ] T is the feedback gain of the observer, are the lumped disturbance terms and the observed values ​​of the inductor current.

[0061] The error between the state variable and the observed value at time k+1 is defined as:

[0062]

[0063] In order to ensure the stability of the observer, a suitable feedback gain value is selected so that (A d -HC d ) matrix stabilization, that is, the closed-loop poles are located in the left half of the complex plane, which can make the observation error As time goes by, it approaches zero, that is, the observed value tends to the actual value, and the matrix (A d -HC d )’s eigenvalue p 1 、p 2 Must satisfy p 1 ,p 2 <0. Therefore, the observation error gradually decreases over time, and the state variable D i Observed values replace.

[0064] Load equivalent resistance observation, taking output voltage and output current as state variables, write the discrete mathematical model as:

[0065]

[0066] in, C o =[1 0], I L =[i L1 i L2 i L3 ] T .

[0067] The disturbance observer is designed as:

[0068]

[0069] Where L = [L 1 L 2 ] T is the feedback gain of the observer, are the observed values ​​of output voltage and output current.

[0070] The error between the state variable and the observed value at time k+1 is defined as:

[0071]

[0072] Select appropriate feedback gain L 1 and L 2 A o -LC o ) is stable, and the load equivalent resistance is replaced by the observed value instead of the actual value.

[0073] (2) For Buck working mode:

[0074] Outer loop perturbation observation: According to the discrete mathematical model in step 1, the term to be observed is defined as:

[0075]

[0076] Define the disturbance term and output voltage as state variables and write the discrete mathematical model as follows:

[0077]

[0078] The disturbance observer is designed as:

[0079]

[0080] Among them, F 1 、F 2is the feedback gain of the observer, is the observed value of the output voltage and the external loop disturbance term; select a suitable feedback gain F 1 、F 2 , replacing the actual value with the observed disturbance term.

[0081] Inner loop disturbance observation, according to the discrete mathematical model of step 1, the term to be observed is defined as:

[0082]

[0083] Taking the disturbance term and inductor current as state variables, the discrete mathematical model of the system is rewritten as:

[0084]

[0085] The disturbance observer is designed as:

[0086]

[0087] Among them, G 1 , G 2 is the feedback gain of the observer, is the observed value of the inductor current and the inner loop disturbance term; select a suitable feedback gain G 1 , G 2 , replacing the actual value with the observed disturbance term.

[0088] Further, in step 3, the observed state variables are compensated online to the prediction model according to the system mathematical model and the Lumberg disturbance observer, and the error feedback and observed disturbance feedforward control methods are used, combined with the continuous set model predictive control based on the deadbeat method to adjust the optimal control quantity output by the converter in the forward and reverse working modes respectively, including:

[0089] Compensate the observed state variables into the prediction model online:

[0090] (1) In Boost working mode:

[0091] Outer loop output current reference value:

[0092] Inner loop output control quantity:

[0093] (2) In Buck working mode:

[0094] Outer loop output current reference value:

[0095] Inner loop output control quantity:

[0096] Further, in step 4, the optimal control quantity duty cycle is sent to the CPS-PWM module to obtain a pulse signal of the three-phase switch tube, including:

[0097] The optimal control quantity duty ratio u 1 、u 2 、u 3 The modulation module is used to obtain the pulse signal of the three-phase switch tube. The modulation method adopts CPS-PWM mode. The duty cycle output of each phase modulates the three triangular carriers. The frequency amplitude of the triangular carrier of each phase is equal, and the phase lags in sequence. carrier cycles, so that the on-time of each phase switch lags by 120° in sequence.

[0098] The object of the present invention is to provide a bidirectional DC / DC conversion device based on disturbance observation predictive control using the bidirectional DC / DC conversion method based on disturbance observation predictive control, wherein the bidirectional DC / DC conversion device based on disturbance observation predictive control comprises:

[0099] A discrete mathematical model building module is used to determine the state variables, state equations and parameters of a bidirectional half-bridge DC / DC converter and establish a discrete mathematical model of the converter;

[0100] Dynamic response speed control module, which is used to improve the dynamic response speed of the overall control system in the current control mode, with the outer loop based on the power balance principle and the inner loop using the model predictive control method;

[0101] The working mode design module is used to design the Lumberg disturbance observer of the bidirectional half-bridge DC / DC converter in the forward and reverse working modes, i.e., the three-phase interleaved parallel Boost and Buck modes, respectively, according to the discrete mathematical model of the system;

[0102] The optimal control quantity adjustment module is used to compensate the observed state variables to the prediction model online according to the system mathematical model and the Lumberg disturbance observer, and adopt error feedback and observed disturbance feedforward control methods, combined with the continuous set model predictive control based on the deadbeat method, to adjust the optimal control quantity output by the converter in the forward and reverse working modes respectively;

[0103] The pulse signal acquisition module is used to send the optimal control quantity duty cycle to the CPS-PWM module to obtain the pulse signal of the three-phase switch tube.

[0104] Another object of the present invention is to provide a computer device, the computer device comprising a memory and a processor, the memory storing a computer program, and when the computer program is executed by the processor, the processor performs the following steps:

[0105] According to the mathematical model of the circuit, the inner and outer loop predictive control models of the converter working in Boost mode and Buck mode are established. The Lumberg disturbance observer in the forward and reverse direction modes is designed and compensated online to the predictive model. The error feedback and observed disturbance feedforward are used to realize the model predictive control of the continuous set based on the deadbeat method. The optimal control quantity in each working mode is obtained, and the optimal control duty cycle is sent to the carrier phase-shift PWM module CPS-PWM to obtain the switching pulse signal.

[0106] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor executes the bidirectional DC / DC conversion method based on disturbance observation predictive control.

[0107] Another object of the present invention is to provide an information data processing terminal, which is used to realize the function of the bidirectional DC / DC conversion device based on disturbance observation and predictive control.

[0108] In combination with all the above-mentioned technical solutions, the advantages and positive effects of the present invention are as follows: the bidirectional DC / DC conversion method based on disturbance observation predictive control provided by the present invention is based on the model predictive control strategy, realizes the CPS-PWM-based zero-beat predictive control, and combines the Lumberg disturbance observer to realize the control strategy suitable for the three-phase staggered parallel bidirectional half-bridge DC / DC converter, which can meet the requirements of the staggered parallel bidirectional DC / DC converter under the conditions of load disturbance, input voltage disturbance, and the presence of inductance resistance. It can still accurately and quickly track the load voltage reference, and solve the problem of converter instability caused by external disturbance and internal model mismatch in traditional model predictive control methods, and the output cannot accurately and quickly track the reference.

[0109] The present invention provides a model predictive control method for a three-phase interleaved parallel bidirectional half-bridge DC-DC converter combined with a Lumberg disturbance observer. The method retains the advantage of fast dynamic response speed of traditional model predictive control, can accurately and quickly track the given value in the presence of external disturbances and internal model mismatch, and has strong anti-interference ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0110] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0111] Figure 1It is a flow chart of a bidirectional DC / DC conversion method based on disturbance observation predictive control provided by an embodiment of the present invention.

[0112] Figure 2 It is a structural block diagram of a bidirectional DC / DC converter device based on disturbance observation and predictive control provided by an embodiment of the present invention;

[0113] In the figure: 1. Discrete mathematical model building module; 2. Dynamic response speed control module; 3. Working mode design module; 4. Optimal control quantity adjustment module; 5. Pulse signal acquisition module.

[0114] FIG3 is an overall control block diagram of a bidirectional DC / DC converter based on disturbance observation and predictive control provided by an embodiment of the present invention.

[0115] FIG. 3( a ) is a schematic diagram of a Boost working mode provided in an embodiment of the present invention.

[0116] FIG3( b ) is a schematic diagram of the Buck working mode provided by an embodiment of the present invention.

[0117] Figure 4 It is a circuit topology diagram of a three-phase interleaved parallel bidirectional half-bridge DC-DC converter provided by an embodiment of the present invention.

[0118] Figure 5 It is a waveform diagram of the carrier phase-shift pulse width modulation method provided by an embodiment of the present invention.

[0119] FIG6 is a waveform diagram of simulation results of the control method provided by an embodiment of the present invention in the Boost working mode when the system is disturbed and the model is mismatched.

[0120] FIG. 6( a ) is a waveform diagram of a step simulation of an output voltage reference value provided by an embodiment of the present invention.

[0121] FIG6( b ) is a waveform diagram of a simulation of an input voltage step disturbance provided by an embodiment of the present invention.

[0122] FIG6( c ) is a load step disturbance simulation waveform diagram provided by an embodiment of the present invention.

[0123] FIG6( d ) is a waveform diagram of an inductance mismatch simulation provided by an embodiment of the present invention.

[0124] FIG. 7 is a waveform diagram of simulation results of the control method provided by an embodiment of the present invention in the Buck working mode when the system is disturbed and the model is mismatched.

[0125] FIG. 7( a ) is a step simulation waveform diagram of an output voltage reference value provided by an embodiment of the present invention.

[0126] FIG. 7( b ) is a load step disturbance simulation waveform diagram provided by an embodiment of the present invention.

[0127] FIG. 7( c ) is a waveform diagram of an inductance mismatch simulation provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0128] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0129] In view of the problems existing in the prior art, the present invention provides a bidirectional DC / DC conversion device based on disturbance observation and predictive control. The present invention is described in detail below in conjunction with the accompanying drawings.

[0130] like Figure 1 As shown, the bidirectional DC / DC conversion method based on disturbance observation predictive control provided by the embodiment of the present invention includes the following steps:

[0131] S101, determining state variables, state equations and parameters of a bidirectional half-bridge DC / DC converter, and establishing a discrete mathematical model of the converter;

[0132] S102, in the current control mode, the outer loop is based on the power balance principle, and the inner loop adopts the model predictive control method to improve the dynamic response speed of the overall control system;

[0133] S103, according to the discrete mathematical model of the system, respectively designing the Lumberg disturbance observer of the bidirectional half-bridge DC / DC converter in the forward and reverse working modes, i.e., the three-phase interleaved parallel Boost and Buck modes;

[0134] S104, based on the system mathematical model and the Lumberg disturbance observer, the observed state variables are compensated online into the prediction model, and the error feedback and observed disturbance feedforward control methods are adopted, combined with the continuous set model predictive control based on the deadbeat method, to adjust the optimal control quantity output by the converter in the forward and reverse direction working modes respectively;

[0135] S105, sending the optimal control quantity duty cycle to the CPS-PWM module to obtain the pulse signal of the three-phase switch tube.

[0136] like Figure 2 As shown, the bidirectional DC / DC converter device based on disturbance observation predictive control provided by the embodiment of the present invention includes:

[0137] A discrete mathematical model building module 1 is used to determine the state variables, state equations and parameters of the bidirectional half-bridge DC / DC converter and establish a discrete mathematical model of the converter;

[0138] Dynamic response speed control module 2, used for improving the dynamic response speed of the overall control system in the current control mode, with the outer loop based on the power balance principle and the inner loop using the model predictive control method;

[0139] The working mode design module 3 is used to design the Lumberg disturbance observer of the bidirectional half-bridge DC / DC converter in the forward and reverse working modes, i.e., the three-phase interleaved parallel Boost and Buck modes, respectively, according to the discrete mathematical model of the system;

[0140] The optimal control amount adjustment module 4 is used to compensate the observed state variables to the prediction model online according to the system mathematical model and the Lumberg disturbance observer, and adopt error feedback and observed disturbance feedforward control methods, combined with the continuous set model predictive control based on the deadbeat method, to adjust the optimal control amount output by the converter in the forward and reverse working modes respectively;

[0141] The pulse signal acquisition module 5 is used to send the optimal control quantity duty cycle to the CPS-PWM module to obtain the pulse signal of the three-phase switch tube.

[0142] FIG3 is an overall control block diagram of the converter control system of the present invention;

[0143] Figure 4 It is a circuit topology diagram of a three-phase interleaved parallel bidirectional half-bridge DC-DC converter adopted by the present invention;

[0144] Figure 5 It is a waveform diagram of the carrier phase shift pulse width modulation method (CPS-PWM, D is the duty cycle) adopted in the present invention;

[0145] Figure 6(a) to Figure 6(d) They are respectively the simulation result waveforms of the control method proposed by the present invention in the Boost working mode when the system is disturbed and the model is mismatched;

[0146] Figure 7(a) to Figure 7(c) They are respectively the simulation result waveforms of the control method proposed by the present invention in the Buck working mode when the system is disturbed and the model is mismatched.

[0147] The technical solution of the present invention is further described below in conjunction with specific embodiments. 1. Summary of the invention

[0149] The present invention discloses a model predictive control method for a three-phase interleaved parallel bidirectional half-bridge DC / DC converter based on disturbance observation, the method comprising the following steps: calculating and establishing an inner and outer loop predictive control model of the converter working in Boost mode and Buck mode according to a mathematical model of the circuit, designing a Lumberg disturbance observer in the forward and reverse direction mode and compensating it online into the predictive model, adopting error feedback and observed disturbance feedforward, realizing model predictive control of a continuous set based on a deadbeat method, obtaining the optimal control quantity in each working mode, and sending the optimal control duty cycle to a carrier phase shift PWM (CPS-PWM) module to obtain a switch pulse signal. The present invention can meet the requirements that the interleaved parallel bidirectional DC / DC converter can still accurately and quickly track the load voltage reference under load disturbance, input voltage disturbance, and working conditions with inductance and resistance. 2. Summary of the invention

[0151] The purpose of the present invention is to provide a control strategy based on a model predictive control strategy to realize CPS-PWM-based zero-beat predictive control, and to combine a Lumberg disturbance observer to realize a control strategy suitable for a three-phase interleaved parallel bidirectional half-bridge DC / DC converter, so as to solve the problem that the converter is unstable due to external disturbances and internal model mismatch in the traditional model predictive control method, and the output cannot accurately and quickly track the reference.

[0152] The technical solution adopted by the present invention is implemented specifically according to the following steps:

[0153] Step 1: Determine the state variables, state equations and parameters of the bidirectional half-bridge DC / DC converter, and establish a discrete mathematical model of the converter. In the current control mode, the outer loop is based on the power balance principle, and the inner loop uses the model predictive control method to improve the dynamic response speed of the overall control system;

[0154] Step 2, according to the discrete mathematical model of the system, respectively design the Lumberg disturbance observer of the bidirectional half-bridge DC / DC converter in the forward and reverse working modes, i.e., the three-phase interleaved parallel Boost and Buck modes;

[0155] Step 3: According to the system mathematical model and the Lumberg disturbance observer, the observed state variables are compensated online into the prediction model, and the error feedback and observed disturbance feedforward control methods are adopted, combined with the continuous set model predictive control based on the deadbeat method, to adjust the optimal control quantity output by the converter in the forward and reverse working modes respectively;

[0156] Step 4: Send the optimal control duty cycle to the CPS-PWM module to obtain the pulse signal of the three-phase switch tube.

[0157] The present invention can satisfy the requirement that the interleaved parallel bidirectional DC / DC converter can still accurately and quickly track the load voltage reference under the conditions of load disturbance, input voltage disturbance and the presence of inductance resistance.

[0158] 1. Further, the above step 1 specifically includes:

[0159] Establish the converter mathematical model:

[0160] When the converter works in Boost mode, the model is built based on the switch on and off. Based on Kirchhoff's law and state space averaging method, the continuous time mathematical model of the three-phase interleaved parallel Boost converter can be obtained:

[0161]

[0162] Among them, u i (t) is the system input, V in 、V o are the input and output voltages, R o is the equivalent load resistance, C f is the output capacitance, L i (i=1,2,3) is the inductance of each phase, i Li (i=1,2,3) is the inductor current of each phase, R Li (i=1,2,3) is the equivalent series resistance of each phase inductor. Further using forward Euler discretization, the discrete time mathematical model of the converter can be obtained:

[0163]

[0164] Among them, T s is the sampling time, v=V in , A, B, C, E are system coefficient matrices:

[0165]

[0166] x=[i L1 i L2 i L3 V o ].

[0167] The outer loop is based on the power balance principle: According to the model instantaneous power balance theory, the relationship between input and output and the total inductor current reference value is obtained:

[0168]

[0169] The current reference value of each phase is required to be 1 / 3 of the total reference value to achieve current sharing. The inductor current reference value of each phase can be obtained as follows:

[0170]

[0171] The inner loop adopts the model predictive control method: Assuming that the input and output voltages remain constant within a sampling period, the inductor current changes linearly. According to the discrete mathematical model, the inductor current value at time k+1 can be predicted from time k:

[0172]

[0173] The predictive control cost function can be obtained:

[0174] The cost function is respectively applied to the control quantity u i (k) Find the partial derivative and set its derivative equal to 0 to determine the value of the control quantity that minimizes the cost function:

[0175] calculate get: It is output as the control quantity to the CPS-PWM module for modulation.

[0176] When the converter works in Buck mode, the model is built based on the switch on and off. Based on Kirchhoff's law and state space averaging method, the continuous time mathematical model of the three-phase interleaved parallel Buck converter can be obtained:

[0177] Similarly, the discrete-time mathematical model of the converter can be obtained:

[0178] Among them, T s is the sampling time, A, B, C are the system coefficient matrices:

[0179] x=[i L1 i L2 i L3 V o ].

[0180] Similar to the above, according to Kirchhoff's current theory:

[0181] Considering current sharing, the reference value of the inductor current of each phase is:

[0182] Similarly, the inner loop adopts the model predictive control method, and the inductor current value at time k+1 can be predicted from time k:

[0183]

[0184] The cost function can be obtained:

[0185] calculate get: It is output as the control quantity to the CPS-PWM module for modulation.

[0186] 2. Further, the above step 2 specifically includes:

[0187] A Romberg disturbance observer is designed and the observed state variables are compensated online into the prediction model.

[0188] For Boost working mode:

[0189] Lumped disturbance observation: According to the discrete mathematical model in step 1, the lumped disturbance term is defined as: Taking the disturbance term and the inductor current as state variables, the discrete mathematical model of the system can be rewritten as follows:

[0190] Where X di (t) = [i Li D i ] T , C d =[1 0], v d =V o . Then the disturbance observer can be designed as follows:

[0191] Where H = [H 1 H 2 ] T is the feedback gain of the observer, are the lumped disturbance terms and the observed values ​​of the inductor current.

[0192] According to the above formula, the error between the state variable and the observed value at time k+1 is defined as:

[0193]

[0194] In order to ensure the stability of the observer, it is necessary to select an appropriate feedback gain value so that (A d -HC d ) matrix stabilization, that is, the closed-loop poles are located in the left half of the complex plane, which can make the observation error As time goes by, it approaches zero, that is, the observed value approaches the actual value. This means that the matrix (A d -HC d )’s eigenvalue p 1 、p 2 Must satisfy p 1 ,p 2 <0. Therefore, the observation error decreases gradually over time. State variable Di The observed values ​​can be used replace.

[0195] Load equivalent resistance observation, taking output voltage and output current as state variables, write the discrete mathematical model as follows:

[0196] in C o =[1 0], I L =[i L1 i L2 i L3 ] T .

[0197] Then the disturbance observer can be designed as:

[0198] Where L = [L 1 L 2 ] T is the feedback gain of the observer, are the observed values ​​of output voltage and output current.

[0199] Similarly, the error between the state variable and the observed value at time k+1 is defined as:

[0200]

[0201] Select appropriate feedback gain L 1 and L 2 A o -LC o ) is stable, the load equivalent resistance can be replaced by the observed value instead of the actual value, which is:

[0202] Similarly, for Buck working mode:

[0203] Outer loop perturbation observation: According to the discrete mathematical model in step 1, the term to be observed is defined as:

[0204]

[0205] Define the disturbance term and output voltage as state variables and write the discrete mathematical model as follows:

[0206]

[0207] Then the disturbance observer can be designed as: Among them, F 1 、F 2 is the feedback gain of the observer, is the observed value of the output voltage and the external loop disturbance term. Similarly, select the appropriate feedback gain F 1 、F 2 , the observed disturbance term can be used to replace the actual value.

[0208] Inner loop disturbance observation, according to the discrete mathematical model of step 1, the term to be observed is defined as:

[0209]

[0210] Taking the disturbance term and the inductor current as state variables, the discrete mathematical model of the system can be rewritten as follows:

[0211]

[0212] Then the disturbance observer can be designed as follows: Among them G 1 , G 2 is the feedback gain of the observer, is the observed value of the inductor current and the inner loop disturbance term. Similarly, select the appropriate feedback gain G 1 , G 2 , the observed disturbance term can be used to replace the actual value.

[0213] 3. Further, the above step 3 specifically includes:

[0214] Compensate the observed state variables into the prediction model online:

[0215] In Boost working mode:

[0216] Outer loop output current reference value:

[0217] Inner loop output control quantity:

[0218] In Buck working mode:

[0219] Outer loop output current reference value:

[0220] Inner loop output control quantity:

[0221] 4. Further, the above step 4 specifically includes:

[0222] The optimal control quantity duty ratio u 1 、u 2 、u 3 The modulation module is used to obtain the pulse signal of the three-phase switch tube. The modulation method is CPS-PWM, and the amplitude of the triangular carrier frequency of each phase is equal, and the phase lags in sequence. The duty cycle output of each phase modulates the three triangular carriers, so that the on-time of each phase switch lags by 120° in sequence.

[0223] From the above, it can be seen that the present invention provides a model predictive control method for a three-phase interleaved parallel bidirectional half-bridge DC-DC converter combined with a Lumberg disturbance observer. The method retains the advantage of fast dynamic response speed of traditional model predictive control, can accurately and quickly track the given value in the presence of external disturbances and internal model mismatch, and has strong anti-interference ability.

[0224] In the description of the present invention, unless otherwise specified, "plurality" means two or more than two; the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0225] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When the use is implemented in whole or in part in the form of a computer program product, the computer program product includes one or more computer instructions. When the computer program instructions are loaded or executed on a computer, the process or function described in the embodiment of the present invention is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from one website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL) or wireless (e.g., infrared, wireless, microwave, etc.) mode) to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state hard disk SolidState Disk (SSD)), etc.

[0226] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A bidirectional DC / DC conversion method based on disturbance observation predictive control, characterized in that: The bidirectional DC / DC conversion method based on disturbance observation predictive control includes: According to the mathematical model of the circuit, the inner and outer loop predictive control models of the converter working in Boost mode and Buck mode are established, and the Lumberg disturbance observer in the forward and reverse direction modes is compensated online to the inner and outer loop predictive control models. The error feedback and observed disturbance feedforward are adopted to realize the model predictive control of the continuous set based on the deadbeat method, and the optimal control quantity in each working mode is obtained. The optimal control duty cycle is sent to the carrier phase shift PWM module CPS-PWM to obtain the switching pulse signal. The bidirectional DC / DC conversion method based on disturbance observation predictive control comprises the following steps: Step 1: determine the state variables, state equations and parameters of the bidirectional half-bridge DC / DC converter, and establish a discrete mathematical model of the converter; in the current control mode, the outer loop is based on the power balance principle, and the inner loop adopts the model predictive control method to improve the dynamic response speed of the overall control system; Step 2, according to the discrete mathematical model, the Lumberg disturbance observer of the bidirectional half-bridge DC / DC converter in the forward and reverse working modes, i.e., the three-phase interleaved parallel Boost and Buck modes, is designed respectively; Step 3: According to the discrete mathematical model and the Lumberg disturbance observer, the observed state variables are compensated online into the prediction model, and the error feedback and observed disturbance feedforward control methods are adopted, combined with the continuous set model predictive control based on the deadbeat method, to adjust the optimal control quantity output by the converter in the forward and reverse working modes respectively; Step 4: Send the optimal control duty cycle to the CPS-PWM module to obtain the pulse signal of the three-phase switch tube; In step 1, the state variables, state equations and parameters of the bidirectional half-bridge DC / DC converter are determined, and a discrete mathematical model of the converter is established; in the current control mode, the outer loop is based on the power balance principle, and the inner loop adopts the model predictive control method to improve the dynamic response speed of the overall control system, including: (1) Establishing the mathematical model of the converter: When the converter works in the Boost mode, the model is built based on the switch on and off. Based on Kirchhoff's law and the state space averaging method, the continuous time mathematical model of the three-phase interleaved parallel Boost converter is obtained: Among them, u i (t) is the system input, V in 、V o are the input and output voltages, R o is the equivalent load resistance, C f is the output capacitance, L i (i=1,2,3) is the inductance of each phase, i Li (i=1,2,3) is the inductor current of each phase, R Li (i=1,2,3) is the equivalent series resistance of each phase inductor; Using forward Euler discretization, the discrete-time mathematical model of the converter is obtained: Among them, T s is the sampling time, v=V in , A, B, C, E are system coefficient matrices: x=[i L1 i L2 i L3 V o ]; The outer loop is based on the power balance principle: According to the model instantaneous power balance theory, the relationship between input and output and the total inductor current reference value is obtained: The current reference value of each phase is required to be 1 / 3 of the total reference value to achieve current sharing. The inductor current reference value of each phase is obtained as follows: The inner loop adopts the model predictive control method: Assuming that the input and output voltages remain constant within a sampling period, the inductor current changes linearly. According to the discrete mathematical model, the inductor current value at time k+1 is predicted from time k: The predictive control cost function is obtained: The cost function is respectively applied to the control quantity u i (k) Find the partial derivative and set the derivative equal to 0 to determine the value of the control quantity that minimizes the cost function: calculate get: Output as control quantity to CPS-PWM module for modulation; (2) When the converter works in Buck mode, the model is built based on the switch on and off. Based on Kirchhoff's law and state space averaging method, the continuous time mathematical model of the three-phase interleaved parallel Buck converter is obtained: The discrete-time mathematical model of the converter is obtained: Among them, T s is the sampling time, A b ,B b , C is the system coefficient matrix: x=[i L1 i L2 i L3 V o ]; According to Kirchhoff's current theory: Considering current sharing, the reference value of the inductor current of each phase is: The inner loop adopts the model predictive control method, and the inductor current value at time k+1 is predicted from time k: The cost function is obtained: calculate get: It is output as the control quantity to the CPS-PWM module for modulation.

2. The bidirectional DC / DC conversion method based on disturbance observation and predictive control according to claim 1, characterized in that: In step 2, the Lumberg disturbance observer of the bidirectional half-bridge DC / DC converter in the forward and reverse working modes, i.e., three-phase interleaved parallel Boost and Buck modes, is designed according to the discrete mathematical model, including: Design a Lumberg disturbance observer and compensate the observed state variables into the prediction model online; (1) For Boost working mode: Lumped disturbance observation: According to the discrete mathematical model in step 1, the lumped disturbance term is defined as: Taking the disturbance term and the inductor current as state variables, the discrete mathematical model is rewritten as: Among them, X di Represents the state variable in discrete form, X at time k di The value is represented by X di (k)=[i Li D i ] T , k+1 time is X di (k+1), and C d =[1 0], v d =V o ; The disturbance observer is designed as: Where H=[H1 H2] T is the feedback gain of the observer, is the lumped disturbance term and the observed value of the inductor current; The error between the state variable and the observed value at time k+1 is defined as: In order to ensure the stability of the observer, a suitable feedback gain value is selected so that (A d -HC d ) matrix stabilization, that is, the closed-loop poles are located in the left half of the complex plane, which can make the observation error As time goes by, it approaches zero, that is, the observed value tends to the actual value, and the matrix (A d -HC d ) must satisfy p1, p2 < 0; therefore, the observation error decreases over time, and the state variable D i Observed values replace; Load equivalent resistance observation, taking output voltage and output current as state variables, write the discrete mathematical model as: Among them, C o =[1 0], AND L =[and L1 and L2 and L3 ] T ; The disturbance observer is designed as: Where L = [L1 L2] T is the feedback gain of the observer, are the observed values ​​of output voltage and output current; The error between the state variable and the observed value at time k+1 is defined as: Select appropriate feedback gains L1 and L2 to make (A o -LC o ) is stable, and the load equivalent resistance is replaced by the observed value instead of the actual value. (2) For Buck working mode: Outer loop perturbation observation: According to the discrete mathematical model in step 1, the term to be observed is defined as: Define the disturbance term and output voltage as state variables and write the discrete mathematical model as follows: The disturbance observer is designed as: Among them, F1 and F2 are the feedback gains of the observer, are the observed values ​​of the output voltage and the external loop disturbance term; select appropriate feedback gains F1 and F2 to replace the actual value with the observed disturbance term; Inner loop disturbance observation, according to the discrete mathematical model of step 1, the term to be observed is defined as: Taking the disturbance term and the inductor current as state variables, the discrete mathematical model is rewritten as: The disturbance observer is designed as: Among them, G1 and G2 are the feedback gains of the observer, are the observed values ​​of the inductor current and the inner loop disturbance term; select appropriate feedback gains G1 and G2 to replace the actual values ​​with the observed disturbance terms.

3. The bidirectional DC / DC conversion method based on disturbance observation and predictive control according to claim 1, characterized in that: In step 3, the observed state variables are compensated online to the prediction model according to the discrete mathematical model and the Lumberg disturbance observer, and the error feedback and observed disturbance feedforward control methods are used, combined with the continuous set model predictive control based on the deadbeat method to adjust the optimal control quantity output by the converter in the forward and reverse working modes respectively, including: Compensate the observed state variables into the prediction model online: (1) In Boost working mode: Outer loop output current reference value: Inner loop output control quantity: (2) In Buck working mode: Outer loop output current reference value: Inner loop output control quantity:

4. The bidirectional DC / DC conversion method based on disturbance observation and predictive control according to claim 1, characterized in that: In step 4, the optimal control quantity duty cycle is sent to the CPS-PWM module to obtain the pulse signal of the three-phase switch tube, including: The optimal control duty ratios u1, u2, and u3 are sent to the modulation module to obtain the pulse signal of the three-phase switch tube; the modulation method adopts the CPS-PWM method, and the amplitude of the triangular carrier frequency of each phase is equal, and the phase lags in sequence The duty cycle output of each phase modulates the three triangular carriers, so that the on-time of each phase switch lags by 120° in sequence.

5. A bidirectional DC / DC conversion device based on disturbance observation predictive control using the bidirectional DC / DC conversion method based on disturbance observation predictive control as claimed in any one of claims 1 to 4, characterized in that: The bidirectional DC / DC converter based on disturbance observation predictive control comprises: A discrete mathematical model building module is used to determine the state variables, state equations and parameters of a bidirectional half-bridge DC / DC converter and establish a discrete mathematical model of the converter; Dynamic response speed control module, which is used to improve the dynamic response speed of the overall control system in the current control mode, with the outer loop based on the power balance principle and the inner loop using the model predictive control method; The working mode design module is used to design the Lumberg disturbance observer of the bidirectional half-bridge DC / DC converter in the forward and reverse working modes, i.e., the three-phase interleaved parallel Boost and Buck modes, respectively, according to the discrete mathematical model; The optimal control quantity adjustment module is used to compensate the observed state variables to the prediction model online according to the discrete mathematical model and the Lumberg disturbance observer, and adopt the error feedback and observed disturbance feedforward control mode, combined with the continuous set model predictive control based on the deadbeat method, to adjust the optimal control quantity output by the converter in the forward and reverse working modes respectively; The pulse signal acquisition module is used to send the optimal control quantity duty cycle to the CPS-PWM module to obtain the pulse signal of the three-phase switch tube.

6. A computer device, characterized in that: The computer device includes a memory and a processor, the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the bidirectional DC / DC conversion method based on disturbance observation and predictive control as described in any one of claims 1 to 4.

7. A computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor executes the bidirectional DC / DC conversion method based on disturbance observation and predictive control according to any one of claims 1 to 4.

8. An information data processing terminal, used for realizing the function of the bidirectional DC / DC converter based on disturbance observation and predictive control as claimed in claim 5.

Images