Fixed frequency Boost converter control method, system, equipment and medium

Abstract

The invention provides a fixed frequency Boost converter control method, system and device and a medium, and the method comprises the steps: building a corresponding circuit mathematical discrete model according to the circuit topology of a converter; based on a system power balance principle, correcting the circuit mathematical discrete model to obtain a converter prediction control model; according to the converter predictive control model, a predictive control cost model is constructed based on a predictive error minimization principle; according to the predictive control cost model, constructing a duty ratio signal output model based on a minimum predictive control cost principle; obtaining a real-time optimal control output voltage according to a pre-constructed converter passive control model, and inputting the real-time optimal control output voltage into the duty ratio signal output model to generate an optimal duty ratio signal; and controlling the converter to operate according to the optimal duty ratio signal. According to the invention, the dynamic response speed and anti-interference performance of the system can be effectively improved, and reliable guarantee is provided for the dynamic performance of the converter.

Description

Technical Field

[0001] The present invention relates to the technical field of Boost converter control, and in particular to a fixed frequency Boost converter control method, system, computer equipment and storage medium. Background Art

[0002] With the emergence of energy shortage and energy security issues, distributed power generation technology has received widespread attention. Photovoltaic power generation, wind power generation and other new energy sources are integrated into the large power grid through distributed power generation technology, resulting in a large number of photovoltaic modules and energy storage modules connected to microgrids. The DC-DC boost converter has become one of the commonly used interfaces due to its high efficiency and high output voltage level. Among them, the Boost converter is widely used due to its simple topology and stable performance.

[0003] In order to better improve the dynamic performance of power systems, the nonlinear control of boost converters has attracted much attention, and the model predictive control (MPC) method has been widely used in the control design of boost converters because it has the advantages of fast dynamic response, avoiding adjustment of control parameters and increasing system constraints compared with traditional PWM control. Although the traditional finite set model predictive control can meet certain control requirements, its control process will produce variable switching frequency, and the change of switching frequency will produce noise, which will have a greater negative impact on the stability of the system. Therefore, it is urgent to provide a Boost converter control strategy that can improve the dynamic response speed of the system and enhance the system's anti-interference ability to external parameter changes. Summary of the invention

[0004] The purpose of the present invention is to provide a fixed frequency Boost converter control method, which cleverly combines model predictive control technology with passive control technology, and generates a fixed switching frequency Boost converter control strategy with a fixed duty cycle as a control output signal based on model predictive control. While solving the contradiction between overshoot and rapidity caused by the combination of passive control and other controls, it can also solve the problem of negative impact on system stability caused by variable switching frequency generated in the traditional finite set model predictive control process. It can effectively improve the system dynamic response speed and anti-interference without adding additional control loops, and provide reliable guarantee for the dynamic performance of the converter.

[0005] In order to achieve the above objectives, it is necessary to provide a fixed frequency Boost converter control method, system, computer device and storage medium in response to the above technical problems.

[0006] In a first aspect, an embodiment of the present invention provides a fixed frequency Boost converter control method, the method comprising the following steps:

[0007] According to the circuit topology of Boost converter, the corresponding circuit mathematical discrete model is established;

[0008] Based on the system power balance principle, the circuit mathematical discrete model is modified to obtain a converter predictive control model;

[0009] According to the converter predictive control model, a predictive control cost model is constructed based on the prediction error minimization principle;

[0010] According to the predictive control cost model, a duty cycle signal output model is constructed based on the principle of minimizing the predictive control cost;

[0011] According to the pre-constructed converter passive control model, a real-time optimal control output voltage is obtained, and the real-time optimal control output voltage is input into the duty cycle signal output model to generate an optimal duty cycle signal;

[0012] The Boost converter is controlled to operate according to the optimal duty cycle signal.

[0013] Furthermore, the step of establishing a corresponding circuit mathematical discrete model according to the circuit topology of the Boost converter includes:

[0014] According to the circuit topology, a corresponding circuit mathematical model is established;

[0015] The circuit mathematical model is discretized by Euler method to obtain the circuit mathematical discrete model.

[0016] Furthermore, the step of correcting the circuit mathematical discrete model based on the system power balance principle to obtain the converter predictive control model includes:

[0017] Based on the power balance principle, the converter inductor current calculation model is established;

[0018] According to the converter inductor current calculation model, the circuit mathematical discrete model is modified to obtain the converter predictive control model; the converter predictive control model is expressed as:

[0019]

[0020] In the formula,

[0021]

[0022] Among them, i in (m),u in (m), i o (m) and u p(m) respectively represent the inductor current, input voltage, output current and output voltage of the Boost converter at the mth sampling moment; T s represents the sampling period; R, L and C represent the load resistance, inductance and capacitance of the equivalent circuit respectively; s(m) represents the duty cycle of the circuit switch tube at the mth sampling moment.

[0023] Furthermore, the predictive control cost model is expressed as:

[0024]

[0025] Where J represents the total control cost; i in (m),u in (m), i o (m) and u p (m) respectively represent the inductor current, input voltage, output current and output voltage of the Boost converter at the mth sampling moment; and They represent the expected inductor current and expected output voltage at the mth sampling moment respectively; T s represents the sampling period; R, L and C represent the load resistance, inductance and capacitance of the equivalent circuit respectively; s(m) represents the duty cycle of the circuit switch tube at the mth sampling moment.

[0026] Furthermore, the step of constructing a duty cycle signal output model based on the prediction control cost model and the principle of minimizing the prediction control cost includes:

[0027] According to the predictive control cost model, an expression of partial derivative of cost with respect to duty cycle is obtained;

[0028] Obtain a first duty cycle expression when the partial derivative expression of the cost with respect to the duty cycle is zero, and use the first duty cycle expression as the duty cycle signal output model.

[0029] Furthermore, the step of obtaining the real-time optimal control output voltage according to the pre-built converter passive control model includes:

[0030] According to the converter passive control model, a corresponding desired inductor current derivative expression and a desired output voltage derivative expression are obtained;

[0031] According to the desired inductor current derivative expression and the desired output voltage derivative expression, an input voltage expression and an output voltage expression of the converter are obtained;

[0032] According to the output voltage expression, obtaining a second duty cycle expression corresponding to when the output voltage is equal to the expected output voltage;

[0033] The second duty cycle expression is substituted into the input voltage expression to obtain the optimal control output voltage expression, and the real-time optimal control output voltage is obtained based on the optimal control output voltage expression.

[0034] Further, the optimal duty cycle signal is expressed as:

[0035]

[0036] In the formula, i in (m),u in (m) and u p (m) respectively represent the inductor current, input voltage and output voltage of the Boost converter at the mth sampling moment; and They represent the expected inductor current and expected output voltage at the mth sampling moment respectively; T s represents the sampling period; R, L and C represent the load resistance, inductance and capacitance of the equivalent circuit respectively; s(m) represents the duty cycle of the circuit switch tube at the mth sampling moment.

[0037] In a second aspect, an embodiment of the present invention provides a fixed frequency Boost converter control system, the system comprising:

[0038] The circuit model analysis module is used to establish a corresponding circuit mathematical discrete model according to the circuit topology of the Boost converter;

[0039] A predictive control modeling module, used to modify the circuit mathematical discrete model based on the system power balance principle to obtain a converter predictive control model;

[0040] A control cost modeling module, used to construct a predictive control cost model based on the converter predictive control model and the principle of minimizing prediction errors;

[0041] A duty cycle modeling module, used to construct a duty cycle signal output model based on the prediction control cost model and the principle of minimizing the prediction control cost;

[0042] A duty cycle signal generating module, used to obtain a real-time optimal control output voltage according to a pre-built converter passive control model, and input the real-time optimal control output voltage into the duty cycle signal output model to generate an optimal duty cycle signal;

[0043] The converter control module is used to control the operation of the Boost converter according to the optimal duty cycle signal.

[0044] Furthermore, the circuit model analysis module is specifically used for:

[0045] According to the circuit topology, a corresponding circuit mathematical model is established;

[0046] The circuit mathematical model is discretized by Euler method to obtain the circuit mathematical discrete model.

[0047] Furthermore, the predictive control modeling module is specifically used for:

[0048] Based on the power balance principle, the converter inductor current calculation model is established;

[0049] According to the converter inductor current calculation model, the circuit mathematical discrete model is modified to obtain the converter predictive control model; the converter predictive control model is expressed as:

[0050]

[0051] In the formula,

[0052]

[0053] Among them, i in (m),u in (m), i o (m) and u p (m) respectively represent the inductor current, input voltage, output current and output voltage of the Boost converter at the mth sampling moment; T s represents the sampling period; R, L and C represent the load resistance, inductance and capacitance of the equivalent circuit respectively; s(m) represents the duty cycle of the circuit switch tube at the mth sampling moment.

[0054] Furthermore, the predictive control cost model is expressed as:

[0055]

[0056] Where J represents the total control cost; i in (m),u in (m), i o (m) and u p (m) respectively represent the inductor current, input voltage, output current and output voltage of the Boost converter at the mth sampling moment; and They represent the expected inductor current and expected output voltage at the mth sampling moment respectively; T s represents the sampling period; R, L and C represent the load resistance, inductance and capacitance of the equivalent circuit respectively; s(m) represents the duty cycle of the circuit switch tube at the mth sampling moment.

[0057] Furthermore, the duty cycle modeling module is specifically used for:

[0058] According to the predictive control cost model, an expression of partial derivative of cost with respect to duty cycle is obtained;

[0059] Obtain a first duty cycle expression when the partial derivative expression of the cost with respect to the duty cycle is zero, and use the first duty cycle expression as the duty cycle signal output model.

[0060] Furthermore, the duty cycle signal generating module is specifically used for:

[0061] According to the converter passive control model, a corresponding desired inductor current derivative expression and a desired output voltage derivative expression are obtained;

[0062] According to the desired inductor current derivative expression and the desired output voltage derivative expression, an input voltage expression and an output voltage expression of the converter are obtained;

[0063] According to the output voltage expression, obtaining a second duty cycle expression corresponding to when the output voltage is equal to the expected output voltage;

[0064] The second duty cycle expression is substituted into the input voltage expression to obtain the optimal control output voltage expression, and the real-time optimal control output voltage is obtained based on the optimal control output voltage expression.

[0065] Further, the optimal duty cycle signal is expressed as:

[0066]

[0067] Among them, i in (m),u in (m) and u p (m) respectively represent the inductor current, input voltage and output voltage of the Boost converter at the mth sampling moment; and They represent the expected inductor current and expected output voltage at the mth sampling moment respectively; T s represents the sampling period; R, L and C represent the load resistance, inductance and capacitance of the equivalent circuit respectively; s(m) Indicated in m The duty cycle of the circuit switch tube at a sampling moment.

[0068] In a third aspect, an embodiment of the present invention further provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above method when executing the computer program.

[0069] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of the above method when executed by a processor.

[0070] The present application provides a fixed frequency Boost converter control method, system, computer device and storage medium, through which the corresponding circuit mathematical discrete model is established according to the circuit topology of the Boost converter, and the circuit mathematical discrete model is corrected based on the system power balance principle to obtain the converter predictive control model, and then the predictive control cost model is constructed based on the converter predictive control model and the prediction error minimization principle, and then the duty cycle signal output model is constructed based on the predictive control cost model and the prediction control cost principle based on the minimization prediction control cost principle, and the real-time optimal control output voltage is obtained according to the pre-constructed converter passive control model, and the real-time optimal control output voltage is input into the duty cycle signal output model to generate the optimal duty cycle signal, and the technical scheme of controlling the operation of the Boost converter according to the optimal duty cycle signal is provided. Compared with the prior art, the fixed frequency Boost converter control method, by cleverly combining the model predictive control technology with the passive control technology, and generating a fixed switching frequency Boost converter control strategy with a fixed duty cycle as the control output signal based on the model predictive control, effectively improves the system dynamic response speed and anti-interference without adding an additional control loop, and provides reliable guarantee for the dynamic performance of the converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 is a flow chart of a fixed frequency Boost converter control method according to an embodiment of the present invention;

[0072] Figure 2 is a schematic diagram of a circuit topology result of a Boost converter in an embodiment of the present invention;

[0073] Figure 3 is a schematic diagram of a control flow of a fixed frequency Boost converter in an embodiment of the present invention;

[0074] Figure 4 Schematic diagram of switching frequency of conventional indefinite frequency finite set model predictive control in an embodiment of the present invention;

[0075] Figure 5 Schematic diagram of switching frequency of fixed frequency finite set model predictive control in an embodiment of the present invention;

[0076] Figure 6 is a waveform diagram of output voltage and output current when the desired output voltage changes in an embodiment of the present invention;

[0077] Figure 7is a schematic diagram of waveforms of system output voltage and output current when load changes in an embodiment of the present invention;

[0078] Figure 8 is a waveform diagram of the output voltage and output current of the system when the input voltage suddenly changes in an embodiment of the present invention;

[0079] Fig. 9 is a structural schematic diagram of a fixed frequency Boost converter control system in an embodiment of the present invention;

[0080] Fig.10 It is a diagram of the internal structure of a computer device in an embodiment of the present invention. DETAILED DESCRIPTION

[0081] In order to make the purpose, technical scheme and beneficial effects of the present application clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Obviously, the embodiments described below are part of the embodiments of the present invention and are only used to illustrate the present invention, but are not used to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0082] The fixed frequency Boost converter control method provided by the present invention can be understood as the application status that the control design of the existing Boost converter is difficult to ensure the stability of the system while improving the dynamic response speed of the system. The proposed fixed switching frequency Boost converter control strategy can be used to cleverly combine the model predictive control technology with the passive control technology, and generate a fixed duty cycle as the control output signal based on the model predictive control. It can not only avoid the contradiction between the overshoot and rapidity caused by the combination of passive control and other controls, but also solve the problem that the variable switching frequency generated in the traditional finite set model predictive control process has a negative impact on the stability of the system. The following embodiments will explain the fixed frequency Boost converter control method of the present invention in detail.

[0083] In one embodiment, Figure 1 As shown, a fixed frequency Boost converter control method is provided, comprising the following steps:

[0084] S11. According to the circuit topology of the Boost converter, a corresponding circuit mathematical discrete model is established; wherein the circuit topology can be understood as Figure 2 The equivalent circuit of the Boost converter is shown in the figure, where S represents the switch and u in 、i in 、u p and i oRespectively represent the input voltage, inductor current, output voltage and output current of the Boost converter; R, L, C and VD represent the load resistance, inductor, capacitor and rectifier diode respectively. Correspondingly, the circuit mathematical discrete model can be understood as a model obtained by discretizing the Boost circuit mathematical model using the Euler method at a higher sampling frequency.

[0085] Specifically, the step of establishing a corresponding circuit mathematical discrete model according to the circuit topology of the Boost converter includes:

[0086] According to the circuit topology, a corresponding circuit mathematical model is established; wherein the circuit mathematical model is expressed as:

[0087]

[0088] Among them, u in 、i in and u p Respectively Figure 1 The input voltage, inductor current and output voltage of the equivalent circuit shown; R, L and C represent the load resistance, inductance and capacitance of the equivalent circuit respectively; s represents the duty cycle of the switch tube of the equivalent circuit; and They represent the derivatives of the inductor current and output voltage with respect to time t respectively.

[0089] The circuit mathematical model is discretized by the Euler method to obtain the circuit mathematical discrete model; wherein the circuit mathematical discrete model can be understood as a discretized expression of the circuit mathematical model shown in formula (1), which is expressed as:

[0090]

[0091] In the formula, u p (m+1) and i in (m+1) respectively represent the predicted values ​​of the output voltage and inductor current of the Boost converter at the m+1th sampling moment; u p (m), i in (m) and s(m) represent the output voltage, inductor current and switch duty cycle of the Boost converter at the mth sampling moment, and s(m)∈{0,1}; T s represents the sampling period; R, L and C represent the load resistance, inductance and capacitance of the equivalent circuit respectively.

[0092] S12. Based on the system power balance principle, the mathematical discrete model of the circuit is modified to obtain a converter predictive control model; wherein the system power balance principle can be understood as the input power of the Boost converter is equal to the output power; the corresponding converter predictive control model can be understood as a predictive control model obtained by modifying the inductor current differential equation shown in formula (2) based on the system power balance principle and predicting the next cycle sampling value based on the current cycle sampling value.

[0093] Specifically, the step of correcting the circuit mathematical discrete model based on the system power balance principle to obtain the converter predictive control model includes:

[0094] Based on the power balance principle, a converter inductor current calculation model is established; the converter inductor current calculation model can be understood as a mathematical expression of the inductor current obtained based on the input power of the converter being equal to the output power, expressed as:

[0095]

[0096] Among them, i in (m),u in (m), i o (m) and u p (m) represent the inductor current, input voltage, output current and output voltage of the Boost converter at the mth sampling moment respectively.

[0097] According to the converter inductor current calculation model, the circuit mathematical discrete model is modified to obtain the converter predictive control model; wherein the converter predictive control model can be understood as a model that can more effectively predict the inductor circuit and the output voltage by substituting the converter inductor current shown in equation (3) into equation (2), which is specifically expressed as:

[0098]

[0099] Among them, u p (m+1) and i in (m+1) respectively represent the predicted values ​​of the output voltage and inductor current of the Boost converter at the m+1th sampling moment; i in (m),u in (m) and u p (m) respectively represent the inductor current, input voltage and output voltage of the Boost converter at the mth sampling moment; T s Represents the sampling period; R, L and C represent the load resistance, inductance and capacitance of the equivalent circuit respectively; s(m)∈{0,1} represents the duty cycle of the circuit switch at the mth sampling moment.

[0100] This embodiment is based on the power balance principle. It reconstructs the converter inductor current calculation model by ignoring the power conversion loss, and corrects the converter predictive control model accordingly. This can effectively improve the system response efficiency and ensure that the system can reach a stable state more quickly after being disturbed.

[0101] S13. According to the converter predictive control model, a predictive control cost model is constructed based on the prediction error minimization principle; wherein the prediction error can be understood as including both the inductor current prediction error and the output voltage prediction error, and the prediction error minimization can be understood as minimizing the sum of the squares of the errors of the two; that is, the model predictive control cost function can be directly constructed according to the sum of the squares of the errors between the predicted value of the converter predictive control model and the expected reference value, and the corresponding switch duty cycle when the model predictive control cost is minimized (the prediction error is minimized) is obtained as the optimal switch duty cycle; the specific model predictive control cost function is expressed as:

[0102]

[0103] In the formula, J 1 and J 2 They represent the inductor current control cost and output voltage control cost respectively.

[0104] The total cost of model predictive control can be obtained by adding the inductor current control cost and the output voltage control cost shown in equation (5). That is, the predictive control cost model is expressed as:

[0105]

[0106] Among them, J represents the total control cost.

[0107] S14. According to the predictive control cost model, a duty cycle signal output model is constructed based on the principle of minimizing the predictive control cost; wherein, minimizing the predictive control cost can be understood as minimizing the total predictive control cost calculated by the predictive control cost model shown in formula (6); the corresponding duty cycle signal output model can be understood as being based on the characteristic that the traditional PWM control method can directly generate a fixed switching frequency. In order to ensure that the PWM control method is continued to be used without changing the original control loop, this embodiment preferably sets the predictive control cost model to no longer output a switching signal, but directly outputs a duty cycle signal that is the same as the traditional PWM control mode. Specifically, the step of constructing the duty cycle signal output model based on the principle of minimizing the predictive control cost according to the predictive control cost model includes:

[0108] According to the predictive control cost model, the partial derivative expression of cost with respect to duty cycle is obtained; wherein the partial derivative expression of cost with respect to duty cycle is expressed as:

[0109]

[0110] Where, s represents the duty cycle signal; represents the partial derivative of the total control cost with respect to the duty cycle signal.

[0111] Obtain a first duty cycle expression when the partial derivative expression of the cost with respect to the duty cycle is zero, and use the first duty cycle expression as the duty cycle signal output model; wherein the duty cycle signal output model can be understood as a mathematical expression of the duty cycle signal s obtained by taking the s variable as the solution variable when equation (7) is set equal to zero, expressed as:

[0112]

[0113] in, S(m) Represents the duty cycle signal corresponding to the mth sampling moment.

[0114] This embodiment establishes a direct connection between the duty cycle signal and the model predictive control method by minimizing the predictive control cost, so that the model predictive control no longer outputs a switching signal but directly outputs a duty cycle signal that is the same as the traditional PWM control mode through the duty cycle signal output model shown in formula (8), which is directly used to control the operation of the converter, thereby achieving the goal of effectively improving the system's dynamic response efficiency and anti-interference ability to cope with external parameter changes without adding additional control loops.

[0115] In practical applications, the above-mentioned improved model predictive control strategy can solve the defects of model predictive control of existing converters. However, in order to reduce the computational complexity of model predictive control while increasing system stability, so as to further speed up the response speed of the system, this embodiment preferably introduces the following method of passive control into the model predictive control method, thereby improving the robustness of the system under various operating conditions while effectively saving computing resources and improving computing efficiency.

[0116] S15. According to the pre-constructed converter passive control model, a real-time optimal control output voltage is obtained, and the real-time optimal control output voltage is input into the duty cycle signal output model to generate an optimal duty cycle signal; wherein the converter passive control model can be understood as a passive controller model constructed based on the existing converter passive control design concept, and the specific construction process is as follows:

[0117] Construct the passive control state equation:

[0118]

[0119] in, x=[x 1 x 2 ] T=[i in u p ] T ,

[0120] Based on the design concept of passive control, in and is the desired inductor current and output voltage, then passive control eventually makes the state variable x approach x * .

[0121] Set the state vector error to e = xx * , we can get the Euler-Lagrange (EL) model shown in formula (2):

[0122]

[0123] In the formula, represents the derivative of the error, Represents x * The derivative of .

[0124] The error energy storage function of the constructed system is expressed as:

[0125]

[0126] In the formula, H e (x) represents the error energy corresponding to the state variable x.

[0127] In order to make the error energy storage function shown in equation (11) converge quickly to 0, damping needs to be injected into the system, and the injected damping is shown in equation (12):

[0128]

[0129] In the formula, R p represents the positive definite damping matrix; R 1p and R 2p represents positive definite damping, and R 1p >0、R 2p >0.

[0130] Based on formula (12), the EL model shown in formula (10) can be converted into:

[0131]

[0132] Let equation (13) be zero, and the converter passive control model can be expressed as:

[0133]

[0134] Through the above steps, a converter passive control model applied to converter control can be obtained. Subsequently, the optimal control output voltage of the system can be directly calculated in real time based on the converter passive control model, and this can be applied to the duty cycle signal output model constructed based on the above predictive control method to calculate the optimal duty cycle signal of the switch tube that can be directly used for PWM control of the converter. Specifically, the step of obtaining the real-time optimal control output voltage based on the pre-constructed converter passive control model includes:

[0135] According to the converter passive control model, the corresponding expected inductor current derivative expression and expected output voltage derivative expression are obtained; the specific process of obtaining the expected inductor current derivative expression and the expected output voltage derivative expression is as follows:

[0136] First, expand the converter passive control model shown in equation (14) to obtain:

[0137]

[0138] Based on the first equation in equation (15), the desired inductor current derivative expression is obtained, and based on the second equation in equation (15), the desired output voltage derivative expression is obtained, which is specifically expressed as:

[0139]

[0140] In the formula, and They represent the desired inductor current derivative and the desired output voltage derivative respectively.

[0141] According to the desired inductor current derivative expression and the desired output voltage derivative expression, the input voltage expression and the output voltage expression of the converter are obtained; wherein the input voltage expression and the output voltage expression can be understood as respectively making the expression in equation (16) and is zero, the resulting system description is:

[0142]

[0143] According to the output voltage expression, the second duty cycle expression corresponding to the output voltage being equal to the expected output voltage is obtained; wherein the acquisition of the second duty cycle expression can be understood as making the second equation in equation (17) satisfy The expression for s(m) obtained by the second equation is:

[0144]

[0145] Where s(m) represents the duty cycle based on passive control output.

[0146] Substitute the second duty cycle expression into the input voltage expression to obtain the optimal control output voltage expression, and obtain the real-time optimal control output voltage according to the optimal control output voltage expression; wherein the optimal control output voltage expression can be understood as the u obtained by substituting equation (18) into the first equation in equation (17) p (m) Mathematical expression:

[0147]

[0148] In the formula, u p (m) represents the optimal control output voltage based on the passive control output.

[0149] The real-time optimal control output voltage in this embodiment can be understood as the current optimal control output voltage calculated by substituting the parameters such as the inductor current, input voltage, expected output voltage and expected inductor current of the Boost converter obtained by real-time sampling into formula (19). After obtaining the required real-time optimal control output voltage, it can be input into the duty cycle signal output model shown in formula (8) and combined with other acquisition parameters to generate the optimal duty cycle signal at the corresponding moment. Specifically, the optimal duty cycle signal is expressed as:

[0150]

[0151] Among them, i in (m),u in (m) and u p (m) respectively represent the inductor current, input voltage and output voltage of the Boost converter at the mth sampling moment; and They represent the expected inductor current and expected output voltage at the mth sampling moment respectively; T s represents the sampling period; R, L and C represent the load resistance, inductance and capacitance of the equivalent circuit respectively; s(m) represents the duty cycle of the circuit switch tube at the mth sampling moment.

[0152] This embodiment proposes to introduce passive control into the model predictive control method, so that the model predictive control inherits the power shaping and damping injection of the passive control well, which can ensure the asymptotic stability of the system, and when the system is affected by interference, it can achieve control performance that is better than the existing FCS-MPC (Fractional Control Structure Model Predictive Control) control system.

[0153] S16. Control the operation of the Boost converter according to the optimal duty cycle signal; wherein the Boost converter adopts a PWM control mechanism to control the operation based on the optimal duty cycle signal, which will not be described in detail here.

[0154] The present application embodiment Figure 3 As shown, a corresponding circuit mathematical discrete model is established according to the circuit topology of the Boost converter, and the circuit mathematical discrete model is corrected based on the system power balance principle to obtain the converter predictive control model. Then, according to the converter predictive control model, a predictive control cost model is constructed based on the principle of minimizing the prediction error. Then, according to the predictive control cost model, a duty cycle signal output model is constructed based on the principle of minimizing the predictive control cost. According to the pre-constructed converter passive control model, a real-time optimal control output voltage is obtained, and the real-time optimal control output voltage is input into the duty cycle signal output model to generate an optimal duty cycle signal. The scheme of controlling the operation of the Boost converter according to the optimal duty cycle signal effectively solves the application defect that the control design of the existing Boost converter is difficult to ensure the stability of the system while improving the dynamic response speed of the system. By cleverly combining the model predictive control technology with the passive control technology, and generating a fixed switching frequency Boost converter control strategy with a fixed duty cycle as the control output signal based on the model predictive control, the dynamic response speed and anti-interference of the system are effectively improved without adding an additional control loop, providing a reliable guarantee for the dynamic performance of the converter.

[0155] In addition, in order to verify the application effect of the fixed frequency Boost converter control proposed by the present invention, this embodiment also uses Figure 2 The Boost converter shown in the figure is taken as an example for simulation verification, and the corresponding simulation parameters are shown in Table 1.

[0156] Table 1 Simulation parameters

[0157] Parameter name name Numeric unit DC input voltage uin 50 V Expected output voltage uoref 100 V inductance L 1.5 mh capacitance C 1500 uF Injection Damping Rd 5 W Switching frequency f 20 kHz Load resistance R 50 W PI coefficient KP 0.8 PI coefficient Ki 160 Discrete time Ts 50 uS

[0158] First, simulation verification of the switching frequency of the fixed model predictive control and the non-fixed frequency model predictive control is performed respectively, and the obtained Figure 4 and Figure 5 The verification results shown are Figure 4 The output voltage and output current ripples shown in the figure show that it is difficult for a non-fixed frequency predictive controller to achieve accurate control. Figure 5 The output voltage and output current ripples shown show that the fixed-frequency predictive controller can accurately achieve the control effect; that is, after comparative analysis, it is found that the anti-interference ability of the model predictive control is enhanced after the frequency is fixed.

[0159] Secondly, simulation verification was performed under three conditions: expected voltage mutation, load mutation, and input voltage mutation, and the results were obtained respectively. Figure 6-Figure 8 Results shown: Based on Figure 6It can be seen from the waveform diagram of output voltage and output current when the expected output voltage changes that the initial voltage is set to 50V, the initial expected output voltage is 70V, and the expected output voltage is set to 100V at 0.3S. After adding passive control, the dynamic response speed of the system is accelerated, and the overshoot of the system is reduced; based on Figure 7 As shown in the waveform diagram of the system output voltage and output current when the load changes, it can be seen that the initial voltage is set to 50V, the expected output voltage is 100V, the initial load is set to 50Ω, and a 50Ω resistor is connected in parallel at both ends of the load at 0.3S, and the total resistance becomes 25Ω. The fixed-frequency passive model predictive control has a fast dynamic response speed and there is no overshoot in the process; based on Figure 8 From the waveform diagram of the system output voltage and output current when the input voltage suddenly changes, it can be seen that the initial input voltage is set to 50V and the expected output voltage is 100V. At 0.3S, the input voltage is changed from 50V to 60V. It can be seen that the overshoot of the fixed-frequency passive model predictive control is reduced and the dynamic response speed is accelerated; that is, it has been verified that the fixed-frequency model predictive control has a faster dynamic response speed and no overshoot after adding passive control, and the stability of the system is enhanced.

[0160] Through the above simulation experiments, it can be known that the fixed-frequency Boost converter control method provided by the present invention can effectively improve the stability of the system and achieve uniform control effect of inductor current and output voltage under the condition of fixed switching frequency; at the same time, compared with the existing fixed-frequency model predictive control method, by introducing passive control, the anti-interference ability of the system is enhanced, and it has faster dynamic response speed and no overshoot; in addition, it can also adapt to changes in various operating conditions (various operating conditions).

[0161] It should be noted that although the steps in the above flowchart are shown in sequence according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders.

[0162] In one embodiment, Fig. 9 As shown, a fixed frequency Boost converter control system is provided, the system comprising:

[0163] The circuit model analysis module 1 is used to establish a corresponding circuit mathematical discrete model according to the circuit topology of the Boost converter;

[0164] Predictive control modeling module 2, used to modify the circuit mathematical discrete model based on the system power balance principle to obtain a converter predictive control model;

[0165] A control cost modeling module 3, used to construct a predictive control cost model based on the converter predictive control model and the principle of minimizing prediction errors;

[0166] A duty cycle modeling module 4 is used to construct a duty cycle signal output model based on the prediction control cost model and the principle of minimizing the prediction control cost;

[0167] The duty cycle signal generating module 5 is used to obtain the real-time optimal control output voltage according to the pre-constructed converter passive control model, and input the real-time optimal control output voltage into the duty cycle signal output model to generate the optimal duty cycle signal;

[0168] The converter control module 6 is used to control the operation of the Boost converter according to the optimal duty cycle signal.

[0169] In one embodiment, the circuit model analysis module is specifically used to:

[0170] According to the circuit topology, a corresponding circuit mathematical model is established;

[0171] The circuit mathematical model is discretized by Euler method to obtain the circuit mathematical discrete model.

[0172] In one embodiment, the predictive control modeling module is specifically used to:

[0173] Based on the power balance principle, the converter inductor current calculation model is established;

[0174] According to the converter inductor current calculation model, the circuit mathematical discrete model is modified to obtain the converter predictive control model; the converter predictive control model is expressed as:

[0175]

[0176] In the formula,

[0177]

[0178] Among them, i in (m),u in (m), i o (m) and u p (m) respectively represent the inductor current, input voltage, output current and output voltage of the Boost converter at the mth sampling moment; T s Represents the sampling period; R, L and C represent the load resistance, inductance and capacitance of the equivalent circuit respectively; s(m)∈{0,1} represents the duty cycle of the circuit switch at the mth sampling moment.

[0179] In one embodiment, the predictive control cost model is expressed as:

[0180]

[0181] Where J represents the total control cost; i in (m),u in (m), i o (m) and u p (m) respectively represent the inductor current, input voltage, output current and output voltage of the Boost converter at the mth sampling moment; and They represent the expected inductor current and expected output voltage at the mth sampling moment respectively; T s represents the sampling period; R, L and C represent the load resistance, inductance and capacitance of the equivalent circuit respectively; s(m) represents the duty cycle of the circuit switch tube at the mth sampling moment.

[0182] In one embodiment, the duty cycle modeling module is specifically used to:

[0183] According to the predictive control cost model, an expression of partial derivative of cost with respect to duty cycle is obtained;

[0184] Obtain a first duty cycle expression when the partial derivative expression of the cost with respect to the duty cycle is zero, and use the first duty cycle expression as the duty cycle signal output model.

[0185] In one embodiment, the duty cycle signal generating module is specifically used for:

[0186] According to the converter passive control model, a corresponding desired inductor current derivative expression and a desired output voltage derivative expression are obtained;

[0187] According to the desired inductor current derivative expression and the desired output voltage derivative expression, an input voltage expression and an output voltage expression of the converter are obtained;

[0188] According to the output voltage expression, obtaining a second duty cycle expression corresponding to when the output voltage is equal to the expected output voltage;

[0189] The second duty cycle expression is substituted into the input voltage expression to obtain the optimal control output voltage expression, and the real-time optimal control output voltage is obtained based on the optimal control output voltage expression.

[0190] In one embodiment, the optimal duty cycle signal is expressed as:

[0191]

[0192] Among them, iin (m),u in (m) and u p (m) respectively represent the inductor current, input voltage and output voltage of the Boost converter at the mth sampling moment; and They represent the expected inductor current and expected output voltage at the mth sampling moment respectively; T s represents the sampling period; R, L and C represent the load resistance, inductance and capacitance of the equivalent circuit respectively; s(m) represents the duty cycle of the circuit switch tube at the mth sampling moment.

[0193] For the specific definition of the fixed frequency Boost converter control system, please refer to the definition of the fixed frequency Boost converter control method above, and the corresponding technical effects can also be obtained equivalently, which will not be repeated here. Each module in the above-mentioned fixed frequency Boost converter control system can be implemented in whole or in part by software, hardware and a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory in the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[0194] Fig.10 FIG. 1 shows an internal structure diagram of a computer device in an embodiment, and the computer device may specifically be a terminal or a server. Fig.10 As shown, the computer device includes a processor, a memory, a network interface, a display, a camera and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a fixed frequency Boost converter control method is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covered on the display screen, or a key, trackball or touch pad set on the computer device housing, or an external keyboard, touch pad or mouse, etc.

[0195] It can be understood by those skilled in the art that Fig.10 The structure shown in the figure is only a block diagram of a part of the structure related to the present application scheme, and does not constitute a limitation on the computer device to which the present application scheme is applied. The specific computing device may include more or fewer components than shown in the figure, or combine certain components, or have the same component arrangement.

[0196] In one embodiment, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the steps of the above method are implemented when the processor executes the computer program.

[0197] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the above method are implemented.

[0198] In summary, an embodiment of the present invention provides a fixed-frequency Boost converter control method and system, wherein the fixed-frequency Boost converter control method realizes establishing a corresponding circuit mathematical discrete model according to the circuit topology of the Boost converter, and after correcting the circuit mathematical discrete model based on the system power balance principle to obtain a converter predictive control model, a predictive control cost model is constructed based on the converter predictive control model and the principle of minimizing the prediction error, and then a duty cycle signal output model is constructed based on the predictive control cost model and the principle of minimizing the predictive control cost, and a real-time optimal control output voltage is obtained according to a pre-constructed converter passive control model, and the real-time optimal control output voltage is input into the duty cycle signal output model to generate an optimal duty cycle signal, and a technical solution for controlling the operation of the Boost converter according to the optimal duty cycle signal is provided. The method cleverly combines the model predictive control technology with the passive control technology, and generates a fixed switching frequency Boost converter control strategy with a fixed duty cycle as the control output signal based on the model predictive control, so as to effectively improve the system dynamic response speed and anti-interference without adding an additional control loop, thereby providing a reliable guarantee for the dynamic performance of the converter.

[0199] Each embodiment in this specification is described in a progressive manner, and the same or similar parts of each embodiment can be directly referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. It should be noted that the technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0200] The above-mentioned embodiments only express several preferred implementation modes of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in the technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be regarded as the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be based on the protection scope of the claims.

Claims

1. A fixed frequency Boost converter control method, characterized in that: The method comprises the following steps: According to the circuit topology of Boost converter, the corresponding circuit mathematical discrete model is established; Based on the system power balance principle, the circuit mathematical discrete model is modified to obtain a converter predictive control model; According to the converter predictive control model, a predictive control cost model is constructed based on the prediction error minimization principle; According to the predictive control cost model, a duty cycle signal output model is constructed based on the principle of minimizing the predictive control cost; According to the pre-constructed converter passive control model, a real-time optimal control output voltage is obtained, and the real-time optimal control output voltage is input into the duty cycle signal output model to generate an optimal duty cycle signal; The Boost converter is controlled to operate according to the optimal duty cycle signal.

2. The fixed frequency Boost converter control method according to claim 1, characterized in that: The step of establishing a corresponding circuit mathematical discrete model according to the circuit topology of the Boost converter comprises: According to the circuit topology, a corresponding circuit mathematical model is established; The circuit mathematical model is discretized by Euler method to obtain the circuit mathematical discrete model.

3. The fixed frequency Boost converter control method according to claim 1, characterized in that: The step of correcting the circuit mathematical discrete model based on the system power balance principle to obtain the converter predictive control model includes: Based on the power balance principle, the converter inductor current calculation model is established; According to the converter inductor current calculation model, the circuit mathematical discrete model is modified to obtain the converter predictive control model; the converter predictive control model is expressed as: In the formula, in, iin(m) , uin(m) , io(m) and up(m) Respectively represent m The inductor current, input voltage, output current and output voltage of the Boost converter at each sampling moment; Ts Indicates the sampling period; R , L and C They represent the load resistance, inductance and capacitance of the equivalent circuit respectively; s(m) Indicated in m The duty cycle of the circuit switch tube at a sampling moment.

4. The fixed frequency Boost converter control method as claimed in claim 3, characterized in that: The predictive control cost model is expressed as: in, J It means controlling the total cost; iin(m) , uin(m) , io(m) and up(m) Respectively represent m The inductor current, input voltage, output current and output voltage of the Boost converter at each sampling moment; and Respectively represent m The expected inductor current and expected output voltage at each sampling moment; Ts Indicates the sampling period; R , L and C They represent the load resistance, inductance and capacitance of the equivalent circuit respectively; s(m) Indicated in m The duty cycle of the circuit switch tube at a sampling moment.

5. The fixed frequency Boost converter control method according to claim 1, characterized in that: The step of constructing a duty cycle signal output model based on the prediction control cost model and minimizing the prediction control cost principle comprises: According to the predictive control cost model, an expression of partial derivative of cost with respect to duty cycle is obtained; Obtain a first duty cycle expression when the partial derivative expression of the cost with respect to the duty cycle is zero, and use the first duty cycle expression as the duty cycle signal output model.

6. The fixed frequency Boost converter control method according to claim 1, characterized in that: The step of obtaining the real-time optimal control output voltage according to the pre-built converter passive control model comprises: According to the converter passive control model, a corresponding desired inductor current derivative expression and a desired output voltage derivative expression are obtained; According to the desired inductor current derivative expression and the desired output voltage derivative expression, an input voltage expression and an output voltage expression of the converter are obtained; According to the output voltage expression, obtaining a second duty cycle expression corresponding to when the output voltage is equal to the expected output voltage; The second duty cycle expression is substituted into the input voltage expression to obtain the optimal control output voltage expression, and the real-time optimal control output voltage is obtained based on the optimal control output voltage expression.

7. The fixed frequency Boost converter control method according to claim 1, characterized in that: The optimal duty cycle signal is expressed as: in, iin(m) , uin(m) and up(m) Respectively represent m The inductor current, input voltage and output voltage of the Boost converter at each sampling moment; and Respectively represent m The expected inductor current and expected output voltage at each sampling moment; Ts Indicates the sampling period; R , L and C They represent the load resistance, inductance and capacitance of the equivalent circuit respectively; s(m) Indicated in m The duty cycle of the circuit switch tube at a sampling moment.

8. A fixed frequency Boost converter control system, characterized in that: The system comprises: The circuit model analysis module is used to establish a corresponding circuit mathematical discrete model according to the circuit topology of the Boost converter; A predictive control modeling module, used to modify the circuit mathematical discrete model based on the system power balance principle to obtain a converter predictive control model; A control cost modeling module, used for constructing a predictive control cost model based on the prediction error minimization principle according to the converter predictive control model; A duty cycle modeling module, used to construct a duty cycle signal output model based on the prediction control cost model and the principle of minimizing the prediction control cost; A duty cycle signal generating module, used to obtain a real-time optimal control output voltage according to a pre-built converter passive control model, and input the real-time optimal control output voltage into the duty cycle signal output model to generate an optimal duty cycle signal; The converter control module is used to control the operation of the Boost converter according to the optimal duty cycle signal.

9. The fixed frequency Boost converter control system as claimed in claim 8, characterized in that: The circuit model analysis module is specifically used for: According to the circuit topology, a corresponding circuit mathematical model is established; The circuit mathematical model is discretized by Euler method to obtain the circuit mathematical discrete model.

10. The fixed frequency Boost converter control system as claimed in claim 8, characterized in that: The predictive control modeling module is specifically used for: Based on the power balance principle, the converter inductor current calculation model is established; According to the converter inductor current calculation model, the circuit mathematical discrete model is modified to obtain the converter predictive control model; the converter predictive control model is expressed as: In the formula, in, iin(m) , uin(m) , io(m) and up(m) Respectively represent m The inductor current, input voltage, output current and output voltage of the Boost converter at each sampling moment; Ts Indicates the sampling period; R , L and C They represent the load resistance, inductance and capacitance of the equivalent circuit respectively; s(m) ∈{0,1} means in the m The duty cycle of the circuit switch tube at a sampling moment.

11. The fixed frequency Boost converter control system as claimed in claim 10, characterized in that: The predictive control cost model is expressed as: in, J It means controlling the total cost; iin(m) , uin(m) , io(m) and up(m) Respectively represent m The inductor current, input voltage, output current and output voltage of the Boost converter at each sampling moment; and Respectively represent m The expected inductor current and expected output voltage at each sampling moment; Ts Indicates the sampling period; R , L and C They represent the load resistance, inductance and capacitance of the equivalent circuit respectively; s(m) Indicated in m The duty cycle of the circuit switch tube at a sampling moment.

12. The fixed frequency Boost converter control system as claimed in claim 8, characterized in that: The duty cycle modeling module is specifically used for: According to the predictive control cost model, an expression of partial derivative of cost with respect to duty cycle is obtained; Obtain a first duty cycle expression when the partial derivative expression of the cost with respect to the duty cycle is zero, and use the first duty cycle expression as the duty cycle signal output model.

13. The fixed frequency Boost converter control system as claimed in claim 8, characterized in that: The duty cycle signal generating module is specifically used for: According to the converter passive control model, a corresponding desired inductor current derivative expression and a desired output voltage derivative expression are obtained; According to the desired inductor current derivative expression and the desired output voltage derivative expression, an input voltage expression and an output voltage expression of the converter are obtained; According to the output voltage expression, obtaining a second duty cycle expression corresponding to when the output voltage is equal to the expected output voltage; The second duty cycle expression is substituted into the input voltage expression to obtain the optimal control output voltage expression, and the real-time optimal control output voltage is obtained based on the optimal control output voltage expression.

14. The fixed frequency Boost converter control system as claimed in claim 8, characterized in that: The optimal duty cycle signal is expressed as: in, iin(m) , uin(m) and up(m) Respectively represent m The inductor current, input voltage and output voltage of the Boost converter at each sampling moment; and Respectively represent m The expected inductor current and expected output voltage at each sampling moment; Ts Indicates the sampling period; R , L and C They represent the load resistance, inductance and capacitance of the equivalent circuit respectively; s(m) Indicated in m The duty cycle of the circuit switch tube at a sampling moment.

15. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

16. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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