A high-voltage sensor-free accurate voltage-sharing control method for ISOP converter

Abstract

The application discloses a high-voltage sensor-free precise voltage-sharing control method for an ISOP converter and relates to the technical field of direct-current converter control. The method comprises the following steps: according to an output voltage reference value and a feedforward coefficient of an ISOP combined converter system, combining circuit dynamic element parameters, establishing a module state equation, and determining the state equation of a current module through a current module effective duty ratio and a transformer primary and secondary side variable turn ratio; based on the state equation of the current module, a reference equation is established by using an input voltage identification value and an output resistance identification value, and a parameter identification value is updated through an adaptive controller until error convergence; according to the product of the input voltage identification value and the feedforward coefficient, combining the output voltage reference value, outputting a duty ratio signal through a voltage compensator and a current compensator, and generating a driving signal to control the on-off of a switch tube. The application realizes high-voltage sensor-free input side voltage sharing by using a model reference adaptive mode for parameter identification.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of direct current converter control, in particular to a high-voltage sensor-free accurate voltage-sharing control method for ISOP converter. BACKGROUND

[0002] DC medium and high voltage power supply technology is widely used in power supply systems due to its high transmission efficiency, large power, good expansibility and other advantages. The power supply system needs to change the medium and high voltage DC power into stable low voltage DC power through an energy converter to supply power to the next stage circuit. Due to the long distance of the power supply system and the large variation of the load side current, the energy converter is required to be able to operate stably under the conditions of wide range of input variation and sudden change of load, and to output high-quality energy. The system composed of isolated DC / DC converters with input series output parallel (ISOP) is widely used in medium and high voltage power supply technology, and can well meet the application scenarios of high input voltage, low output voltage and large current output. For the ISOP system, stable and balanced operation of each module, i.e. equal sharing of input voltage at the input side and equal sharing of load current at the output side, is crucial to the stability of the system.

[0003] For the balanced control of the ISOP system, the research of domestic and foreign scholars mainly focuses on two aspects: using module characteristics to achieve natural balance and using special control loop to achieve balance. Among them, the methods of using module characteristics to achieve natural balance include common duty ratio control and common magnetic core winding structure. These methods are simple to implement, but the balance effect is not good when the parameters of each module are inconsistent, and the degree of modularization is poor. In the methods of using special control loop to achieve balance, only achieving equal sharing of output current cannot achieve the purpose of stable operation of the system, and achieving equal sharing of input voltage is necessary to achieve balanced and stable operation of each module. The commonly used control methods include the double-loop control method of common output voltage loop and independent input voltage loop, and the three-loop control method of common output voltage control loop, independent current control loop and independent input voltage control loop. These methods can achieve accurate input voltage sharing.

[0004] However, the existing input voltage sharing control methods all need to sample the input voltage as the feedback signal of the control loop, which requires that the control circuit and sampling circuit of each module must strictly meet the electrical isolation requirement, and as the input voltage increases, the isolation requirement will also increase accordingly. At the same time, when using inter-module interconnection control method, the sampling signal used for control is easy to be disturbed, and signal delay will be generated after passing through multiple processing circuits. Therefore, if the input voltage of each module can be accurately estimated through low-voltage side sampling information, and the estimation result is used for independent voltage-sharing control of each module, the stability of the system can be effectively improved, the modularization requirement of the system can be met, and the shortcomings of the prior art can be overcome.

[0005] At present, there is no effective solution to the problems in the related art. SUMMARY

[0006] In view of the shortcomings of the prior art, the present application provides a high-voltage sensor-free accurate voltage-sharing control method for an ISOP converter, which has the advantages of achieving accurate voltage sharing on the input side through low-voltage side sampling information, performing parameter identification using a model reference adaptive method, and meeting the system modularization requirement, thereby solving the problems of the need for high-voltage sensor sampling, the susceptibility of control signals to interference and delay, and poor system stability in the prior art.

[0007] To achieve the above-mentioned advantages of achieving accurate voltage sharing on the input side through low-voltage side sampling information, performing parameter identification using a model reference adaptive method, and meeting the system modularization requirement, the present application employs the following specific technical solutions:

[0008] A high-voltage sensor-free accurate voltage-sharing control method for an ISOP converter, comprising:

[0009] S1, establishing a module state equation according to an output voltage reference value and a feedforward coefficient of an ISOP combined converter system, in combination with circuit dynamic element parameters, and determining the state equation of the current module through the effective duty ratio of the current module and the primary-secondary winding ratio of the transformer;

[0010] S2, establishing a reference equation using an input voltage identification value and an output resistance identification value based on the state equation of the current module, and updating the parameter identification value through an adaptive controller until the error converges;

[0011] S3, outputting a duty ratio signal through a voltage compensator and a current compensator according to the product of the input voltage identification value and the feedforward coefficient, in combination with the output voltage reference value, and generating a driving signal to control the on-off of the switching tube.

[0012] Further, the ISOP combined converter system is composed of n input terminals in series and output terminals in parallel, and the module is a mutually independent phase-shifted full-bridge DC / DC converter; the control loop of the module includes a voltage compensator and a current compensator, and the output voltage and output current of the module are collected on the low-voltage side of the transformer secondary side as the feedback signal of the control loop.

[0013] Further, establishing a module state equation according to an output voltage reference value and a feedforward coefficient of an ISOP combined converter system, in combination with circuit dynamic element parameters, and determining the state equation of the current module through the effective duty ratio of the current module and the primary-secondary winding ratio of the transformer includes:

[0014] S11, determining the output voltage reference value and the feedforward coefficient based on the actual output requirement of the ISOP combined converter system, and establishing a module state equation in combination with the circuit dynamic element parameters;

[0015] S12, establishing a linear transformation equation according to the correspondence between the module effective duty ratio and the controller output duty ratio, and determining the current module effective duty ratio;

[0016] S13, determining the state equation of the current module based on the module state equation and substituting the transformer primary and secondary winding ratio and the current module effective duty ratio;

[0017] Wherein, the circuit dynamic element parameters include the output filter inductance and the output capacitance of the current module.

[0018] Further, the expression of the linear transformation equation is:

[0019]

[0020] In the formula, D ek is the effective duty ratio of the kth module; D k is the controller output duty ratio; I Lk is the output current of the kth module; L rk is the resonant inductance of the kth module; V o is the system output voltage; T s is the switching period; N k is the transformer primary and secondary winding ratio of the kth module.

[0021] Further, the expression of the state equation of the current module is:

[0022]

[0023] In the formula, is the switching period average value of the derivative of the output current of the kth module with respect to time; is the switching period average value of the derivative of the system output voltage with respect to time; N k is the transformer primary and secondary winding ratio; L k is the output filter inductance of the kth module; R k is the equivalent load of the module; C k is the output capacitance of the kth module; i Lk is the output current of the kth module; v o is the system output voltage; v ink is the input voltage of the kth module; D ek is the effective duty ratio of the kth module.

[0024] Further, based on the state equation of the current module, a reference equation is established using the input voltage identification value and the output resistance identification value, and the parameter identification value is updated by the adaptive controller until the error converges, including:

[0025] S21, according to the state equation of the current module, the input voltage and the output resistance are replaced by the parameter identification value to be solved, and the parameter identification initial value is determined, and a reference equation is established;

[0026] S22, based on the response speed requirement, the proportional coefficient and the integral coefficient are selected, and the Lyapunov function is used to determine the complex frequency domain of the adaptive approach rate, which is used to update the parameter identification value;

[0027] S23, by comparing the system output voltage, the output current of each module and the corresponding value in the reference equation, the output voltage error and the output current error are obtained, and the parameter identification value is updated based on the adaptive controller until the error converges to zero;

[0028] Wherein, the parameter identification initial value includes the input voltage identification initial value and the output resistance identification initial value, and the parameter identification value includes the input voltage identification value and the output resistance identification value.

[0029] Further, the complex frequency domain expression of the adaptive approach rate is:

[0030]

[0031] In the formula, is the output resistance identification value; R k (0) is the output resistance identification initial value; K PRk and K Pvk are the output resistance identification proportional coefficient and the input voltage identification proportional coefficient respectively; s is a complex variable; e uk is the output voltage error of the kth module; is the output voltage estimation value; is the input voltage identification value; V ink (0) is the input voltage identification initial value; K IRk and K Ivk are the output resistance identification integral coefficient and the input voltage identification integral coefficient respectively; e ik is the output current error of the kth module.

[0032] Further, by comparing the system output voltage, the output current of each module and the corresponding value in the reference equation, the output voltage error and the output current error are obtained, and the parameter identification value is updated based on the adaptive controller until the error converges to zero, including:

[0033] S231, based on the actual output of the system, the system output voltage and the output current of each module are obtained, and compared with the corresponding output voltage value and output current value in the reference equation;

[0034] S232, according to the comparison result, the output voltage error and the output current error of each module are calculated, and the calculation result is input into the adaptive controller;

[0035] S233, output the updated input voltage identification value and output resistance identification value by using the adaptive controller, and make the error converge to zero through multiple iterations.

[0036] Further, according to the product of the input voltage identification value and the feedforward coefficient, the output voltage reference value is combined to output the duty cycle signal through the voltage compensator and the current compensator, and the driving signal is generated to control the on-off of the switch tube, including:

[0037] S31, multiplying the input voltage identification value by the feedforward coefficient, adding the output voltage reference value as a new reference value, and inputting the voltage compensator after subtracting the output voltage sampling value;

[0038] S32, inputting the output of the voltage compensator into the current compensator after subtracting the output current sampling value to obtain the duty cycle signal;

[0039] S33, based on the duty cycle signal output by the current compensator, the driving signal is generated by pulse width modulation control to control the on-off of the switch tube.

[0040] Further, the input signal of the voltage compensator is the product of the input voltage identification value and the feedforward coefficient and the sum of the output voltage; the output signal of the voltage compensator is the reference value of the output current; the output signal of the current compensator is the module duty cycle, and the module driving signal is generated by intersecting with the sawtooth wave.

[0041] Compared with the prior art, the present application provides a high-voltage sensorless precise voltage sharing control method for ISOP converter, which has the following beneficial effects:

[0042] (1) The high-voltage sensorless precise voltage sharing control method provided by the present application has accurate parameter identification and correct control mode, and can realize high-voltage sensorless input side voltage sharing for ISOP type combined converter composed of DC / DC converter, and stable operation of the system; at the same time, the module input voltage is obtained by identification without sampling, the system has high reliability and good stability, and each module completes control independently, the system has high modularization degree and meets the requirement of no interconnection voltage sharing.

[0043] (2) By collecting the module output voltage and output current on the low-voltage side of the transformer secondary side as feedback signals, and combining the model reference adaptive method for parameter identification, voltage sampling on the high-voltage input side is not needed, which effectively avoids the technical difficulty of high-voltage isolation; the present method establishes state equation and reference equation, and accurately identifies the input voltage by using the adaptive controller, which overcomes the technical defects of complex high-voltage sampling circuit and low reliability in the prior art.

[0044] (3) The application adopts an independent module control structure, each module performs parameter identification and control based on its own state equation and reference equation, without signal interconnection between modules; in addition, the adaptive approach rate is designed through Lyapunov function, the parameter identification value is quickly converged, and the identification result is used for control of the voltage compensator and the current compensator, so that the signal interference and delay problems in the traditional interconnection control mode are avoided, and the stability and reliability of the system are significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative effort based on these drawings.

[0046] Figure 1 is a flowchart of an ISOP converter without high-voltage sensor precise voltage-sharing control method according to an embodiment of the present application;

[0047] Figure 2 is a system topology structure diagram of an n-module ISOP combined converter in an ISOP converter without high-voltage sensor precise voltage-sharing control method according to an embodiment of the present application;

[0048] Figure 3 is a control structure diagram of an n-module ISOP combined converter in an ISOP converter without high-voltage sensor precise voltage-sharing control method according to an embodiment of the present application;

[0049] Figure 4 is an input voltage waveform diagram when no identification voltage feedforward is introduced in an ISOP converter without high-voltage sensor precise voltage-sharing control method according to an embodiment of the present application;

[0050] Figure 5 is a parameter identification result waveform diagram of an ISOP converter without high-voltage sensor precise voltage-sharing control method according to an embodiment of the present application;

[0051] Figure 6 is a parameter identification error waveform diagram of an ISOP converter without high-voltage sensor precise voltage-sharing control method according to an embodiment of the present application;

[0052] Figure 7 is an input voltage waveform diagram when identification voltage feedforward is introduced in an ISOP converter without high-voltage sensor precise voltage-sharing control method according to an embodiment of the present application;

[0053] Figure 8The input voltage waveform diagram when the input voltage changes is introduced according to the high-voltage sensor-free accurate voltage-sharing control method of the ISOP converter. DETAILED DESCRIPTION

[0054] To further illustrate the embodiments, the present application provides drawings which are part of the disclosure of the present application and mainly serve to illustrate the embodiments and can be used to explain the operating principle of the embodiments in conjunction with the relevant description of the specification. Those skilled in the art should be able to understand other possible implementations and advantages of the present application in conjunction with these contents. The components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0055] According to an embodiment of the present application, a high-voltage sensor-free accurate voltage-sharing control method of an ISOP converter is provided.

[0056] The present application will be further described in conjunction with the drawings and specific embodiments, as shown in Figure 1 The high-voltage sensor-free accurate voltage-sharing control method of the ISOP converter according to the embodiment of the present application includes:

[0057] S1, according to the output voltage reference value of the ISOP combined converter system and the feedforward coefficient, combining the circuit dynamic element parameters, the module state equation is established, and the state equation of the current module is determined through the current module effective duty ratio and the transformer primary and secondary side variable ratio;

[0058] S2, based on the state equation of the current module, the reference equation is established by using the input voltage identification value and the output resistance identification value, and the parameter identification value is updated by the adaptive controller until the error converges;

[0059] S3, according to the product of the input voltage identification value and the feedforward coefficient, combining the output voltage reference value, outputting the duty ratio signal through the voltage compensator and the current compensator, and generating the driving signal to control the on-off of the switch tube.

[0060] In one embodiment, the ISOP combined converter system is composed of n input terminals in series and output terminals in parallel modules, and the module is a mutually independent phase-shifted full-bridge DC / DC converter; the control loop of the module includes a voltage compensator and a current compensator, and the output voltage and output current of the module are collected on the low-voltage side of the transformer secondary side as the feedback signal of the control loop.

[0061] Specifically, the ISOP combined converter system in the present application is composed of n modules in series at the input end and in parallel at the output end, and each module is a mutually independent phase-shifted full-bridge DC / DC converter. The control loop of each module includes a voltage compensator and an output current compensator, and the module output voltage v o and the output current iLk As the feedback signal, the sampling is carried out at the low voltage side of the transformer secondary side.

[0062] In one embodiment, the input signal of the voltage compensator is the product of the input voltage identification value and the feedforward coefficient and the sum of the output voltage; the output signal of the voltage compensator is the reference value of the output current; the output signal of the current compensator is the module duty cycle, and the module driving signal is generated by intersecting the sawtooth wave.

[0063] Specifically, the input signal of the module voltage compensator in the application is the input voltage identification value multiplied by the feedforward coefficient k n , and added with the output voltage. The output of the voltage compensator is the reference value of the output current. The output of the current compensator is the module duty cycle D k , and the module driving signal is obtained after intersecting the sawtooth wave.

[0064] Specifically, the input voltage identification value in the application is obtained by the model reference adaptive method. The differential equations of the output voltage and the output current are established, the input voltage is taken as the parameter of the differential equation, the output voltage in the reference equation is taken as the output voltage , and the actual collected value v o and i Lk are compared to obtain the errors e u and e ik . The identification error tends to 0 by designing the approaching rate through the Lyapunov function, and the input voltage identification value is obtained.

[0065] In one embodiment, the output voltage reference value and the feedforward coefficient of the ISOP combined converter system are combined with the circuit dynamic element parameters to establish the module state equation, and the state equation of the current module is determined through the current module effective duty cycle and the transformer primary and secondary side variable ratio, which includes:

[0066] S11, based on the actual output requirement of the ISOP combined converter system, the output voltage reference value and the feedforward coefficient are determined, and the module state equation is established in combination with the circuit dynamic element parameters;

[0067] S12, according to the corresponding relationship between the module effective duty cycle and the controller output duty cycle, a linear transformation equation is established, and the current module effective duty cycle is determined;

[0068] S13, based on the module state equation, the transformer primary and secondary side variable ratio and the current module effective duty cycle are substituted to determine the state equation of the current module;

[0069] Among them, the circuit dynamic element parameters include the output filter inductance and the output capacitance of the current module.

[0070] Specifically, ① according to the actual output requirements of the system, the output voltage reference value V ref , the feedforward coefficient k n , the state equation of the n modules is determined according to the dynamic element parameters of the circuit. The expression of the state equation of the kth module (the current module) is:

[0071]

[0072] In the formula, is the switch cycle average value of the time derivative of the output current of the kth module; is the switch cycle average value of the time derivative of the system output voltage; N k is the primary and secondary winding ratio of the transformer; L k is the output filter inductance of the kth module; R k is the equivalent load of the kth module; C k is the output capacitance of the kth module; i Lk is the output current of the kth module; v o is the system output voltage; v ink is the input voltage of the kth module; D ek is the effective duty ratio of the kth module.

[0073] Specifically, D ek is the module effective duty ratio, and the controller output duty ratio D k has the following linear relationship, and the expression of the linear relationship (linear transformation equation) is:

[0074]

[0075] In the formula, D ek is the effective duty ratio of the kth module; D k is the controller output duty ratio; I Lk is the output current of the kth module; L rk is the resonant inductance of the kth module; V o is the system output voltage; T s is the switching period; N k is the primary and secondary winding ratio of the transformer of the kth module.

[0076] In one embodiment, based on the state equation of the current module, the reference equation is established by using the input voltage identification value and the output resistance identification value, and the parameter identification value is updated by the adaptive controller until the error converges, including:

[0077] S21, according to the state equation of the current module, the input voltage and the output resistance are replaced by the to-be-solved parameter identification value, and the parameter identification initial value is determined to establish the reference equation;

[0078] Specifically, ② according to the state equation in ①, for the kth module, the input voltage and output resistance in the state equation are replaced by the to-be-identified parameters and and the initial value V ink (0) and R k (0) of the parameter identification are determined as the reference equation, and the expression of the reference equation is:

[0079]

[0080] In the formula, is the switch cycle average value of the derivative of the estimated value of the output current of the kth module with respect to time; is the estimated value of the output current of the kth module; is the input voltage identification value; is the switch cycle average value of the derivative of the estimated value of the system output voltage; is the output resistance identification value; is the estimated value of the output voltage;

[0081] S22, based on the response speed requirement, selects the proportional coefficient and the integral coefficient, and uses the Lyapunov function to determine the complex frequency domain of the adaptive convergence rate for updating the parameter identification value;

[0082] Specifically, the adaptive convergence rate is obtained according to the Lyapunov function, and the expression of the complex frequency domain of the adaptive convergence rate is:

[0083]

[0084] In the formula, is the output resistance identification value; R k (0) is the initial value of the output resistance identification; K PRk and K Pvk are the output resistance identification proportional coefficient and the input voltage identification proportional coefficient, respectively; s is a complex variable; e uk is the output voltage error of the kth module; is the estimated value of the output voltage; is the input voltage identification value; V ink (0) is the initial value of the input voltage identification; K IRk and K Ivk are the output resistance identification integral coefficient and the input voltage identification integral coefficient, respectively; e ik is the output current error of the kth module.

[0085] Specifically, K PRk and K Pvk are proportional coefficients, K IRk and K Ivk are integral coefficients, which are selected according to the response speed requirement.

[0086] S23. By comparing the system output voltage and the output current of each module with the corresponding values ​​in the reference equation, the output voltage error and output current error are obtained, and the parameter identification values ​​are updated based on the adaptive controller until the error converges to zero; specifically including:

[0087] S231. Based on the actual system output, obtain the system output voltage and the output current of each module, and compare them with the corresponding output voltage and output current values ​​in the reference equation.

[0088] S232. Based on the comparison results, calculate the output voltage error and the output current error of each module, and input the calculation results into the adaptive controller;

[0089] S233. Using an adaptive controller, the updated input voltage identification value and output resistance identification value are output, and the error is converged to zero through multiple iterations.

[0090] The initial values ​​for parameter identification include the initial values ​​for input voltage identification and output resistance identification, and the parameter identification values ​​include the input voltage identification value and the output resistance identification value.

[0091] Specifically, ③ the system output voltage v o Output current i of each module L1 ~i Ln The output voltage value in the reference equation Output current value By comparison, the output voltage error e is obtained. u Output current error e i1 ~e in The error is used as the input to the adaptive controller, and the output parameter identification value is used as the output parameter identification value. and If the error converges to 0 after multiple repetitions, it is considered to be an accurate identification.

[0092] In one embodiment, based on the product of the input voltage identification value and the feedforward coefficient, combined with the output voltage reference value, a duty cycle signal is output through a voltage compensator and a current compensator to generate a drive signal to control the on / off state of the switching transistor, including:

[0093] S31. Multiply the input voltage identification value by the feedforward coefficient, add it to the output voltage reference value to obtain the new reference value, and subtract it from the output voltage sample value to obtain the input voltage compensator.

[0094] S32. Subtract the output current sample value from the voltage compensator's output and input the result into the current compensator to obtain the duty cycle signal;

[0095] S33. Based on the duty cycle signal output by the current compensator, a drive signal is generated through pulse width modulation control to control the switching transistor's on / off state.

[0096] Specifically, ④ will identify the value With feedforward coefficient k n Multiply by the output voltage reference value V ref The sum is used as the output voltage reference value, and is compared with the sampled value v. o The result of the subtraction is fed into the voltage compensator G. vk The voltage compensator output is compared with the sampled value i. Lk Subtract, and then pass the result to the current compensator G. ik The current compensator outputs a duty cycle signal D. k The PWM control generates a drive signal to control the switching transistor's on / off state.

[0097] Specifically, the method proposed in this invention estimates the input voltage of the parameter identification module and introduces it into the control loop to achieve precise voltage equalization on the input side. The following description, in conjunction with the accompanying drawings, explains how this invention achieves its objective.

[0098] like Figure 2 As shown, the ISOP system described in this patent consists of n isolated DC / DC converter modules, which are connected in series on the input side and in parallel on the output side. in V is the total input voltage of the system. in1 ~v inn These are the input voltages for each module. o For the output voltage, i o This represents the total output current. Figure 3 The diagram shown illustrates the structure of the system control method, which includes the following steps:

[0099] Step 1: After power-on, sample the system output voltage v o The output current i of each module L1 ~i Ln Based on the actual output requirements of the system, determine the output voltage reference value V. ref Feedforward coefficient k n ;

[0100] Step II: Identify the initial value V of the parameter. ink (0) and R k (0) Substitute into the reference equation and output the equation value. and The error e is obtained by comparing it with the sampled value of this module. ik and e u The parameter identification values ​​are obtained after calculation through the adaptive process. and Repeat the process until the error converges to 0, at which point the identification is considered accurate.

[0101] Step III: Input voltage identification value With feedforward coefficient kn multiplied, and the output voltage reference value V ref added as a final reference value;

[0102] Step IV, the reference value v refk subtracted from the sampling value v o and transmitted to the voltage compensator G vk The voltage compensator output is subtracted from the sampling value I Lk and transmitted to the current compensator G ik The current compensator outputs a duty cycle signal, which is used to generate a driving signal D k to control the on-off of the switch tube.

[0103] In order to facilitate the understanding of the above technical solutions of the present application, the ISOP system composed of three modules of the phase-shifted full-bridge converter is taken as an example for specific description as follows:

[0104] When the system is stable, the input voltages of the three modules are equally divided, and the output currents are the same. At a certain moment, the input voltage v in1 of module 1 rises due to disturbance, and according to the power relationship, it can be known that the input current i1 of module 1 also rises. At this time, since the total input voltage is unchanged, the input voltages of modules 2 and 3 decrease, and the output currents decrease. The modules are connected in parallel at the output end, and according to Figure 3 , it can be known that the reference voltage v ref1 of module 1 is greater than the output voltage, and the reference voltages of modules 2 and 3 are less than the output voltage; at this time, the duty cycle D1 of module 1 increases, and the duty cycles of modules 2 and 3 decrease. The input voltage of a module is inversely proportional to the duty cycle, so the input voltage v in1 of module 1 decreases, the input voltages of modules 2 and 3 increase, and the system re-operates stably, and the input voltages of the three modules are equally divided.

[0105] Figure 4 The output voltage waveform diagram of the system control loop without introducing the identification voltage feedforward can be seen, and it can be seen that the input ends of the three modules (the input voltage v in1 of module 1, the input voltage v in2 of module 2, and the input voltage v in3 of module 3) do not achieve voltage equalization, and the system does not achieve balanced operation.

[0106] Figures 5-6 In the proposed control method, the identification results of the parameters of module 1 can be seen. It can be seen that through the model reference adaptive method, the input voltage and the output resistance of the module can be accurately identified, and the errors e i and e u converge to 0 after about 0.05s, and the proposed identification method is correct and effective.

[0107] Figure 7The input voltage simulation waveform graphs of each module after the introduction of the identification voltage feedforward are shown. Compared with the case without the introduction of the identification voltage feedforward, the effect is remarkable, the input voltages (v in1 , v in2 , v in3 ) of the three modules are accurately adjusted to 500V after about 0.06s.

[0108] Figure 8 The input voltage simulation waveform graphs of each module when the input voltage changes are shown. The total input voltage of the system jumps from 1500V to 1800V at 0.03s. According to the simulation results, each module realizes the equalization of the input voltage after a short time of adjustment, and the three modules are accurately adjusted to 600V.

[0109] In summary, by means of the above technical solutions of the present application, the identification of the mode parameters is accurate, the control mode is correct, the input side voltage equalization can be realized for the ISOP type combined converter composed of DC / DC converters, and the system can run stably and evenly. The module input voltage is obtained by identification without sampling, the system has high reliability and good stability; each module independently completes the control, the system has high modularization degree, and meets the requirements of no interconnection voltage equalization.

[0110] The above only describes the preferred embodiments of the present application and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A high-voltage sensorless accurate voltage-sharing control method for an ISOP converter, characterized in that, The application relates to a control method of an ISOP combined converter system. S1, establishing a module state equation according to an output voltage reference value and a feedforward coefficient of the ISOP combined converter system, combining a circuit dynamic element parameter, and determining the state equation of a current module through an effective duty ratio of the current module and a primary-secondary winding ratio of a transformer; S2, establishing a reference equation by using an input voltage identification value and an output resistance identification value based on the state equation of the current module, and updating the parameter identification value through an adaptive controller until error convergence; S3, outputting a duty ratio signal through a voltage compensator and a current compensator according to the product of the input voltage identification value and the feedforward coefficient, combining the output voltage reference value, and generating a driving signal to control the on-off of a switch tube; the ISOP combined converter system is composed of n modules in series connection at input ends and in parallel connection at output ends, and the modules are mutually independent phase-shifted full-bridge DC / DC converters; The control loop of the module comprises a voltage compensator and a current compensator, and the output voltage and the output current of the module are collected at a low-voltage side of a secondary side of the transformer as feedback signals of the control loop.

2. The method of claim 1, wherein the ISOP converter is a high-voltage sensorless accurate voltage sharing control method, characterized in that, The method comprises the following steps: S11, determining the output voltage reference value and the feedforward coefficient based on actual output requirements of the ISOP combined converter system, and establishing a module state equation by combining a circuit dynamic element parameter; S12, establishing a linear transformation equation according to the corresponding relationship between the effective duty ratio of the module and the output duty ratio of the controller, and determining the effective duty ratio of the current module; S13, determining the state equation of the current module based on the module state equation, substituting the primary-secondary winding ratio of the transformer and the effective duty ratio of the current module, and determining the state equation of the current module; The circuit dynamic element parameter comprises an output filter inductance and an output capacitance of the current module.

3. The method of claim 2, wherein the ISOP converter is a high-voltage sensorless accurate voltage sharing control method, characterized in that, The expression of the linear transformation equation is: ； where D ek is the effective duty cycle of the kth module; D k is the controller output duty cycle; I Lk is the kth module output current; L rk is the kth module resonant inductance; V o is the system output voltage; T s is the switching period; N k is the transformer primary to secondary turns ratio of the kth module.

4. The method of claim 2, wherein the ISOP converter is a high-voltage sensorless accurate voltage sharing control method, characterized in that, The expression of the state equation of the current module is: ； where, is the average value of the time derivative of the output current of the kth module over the switching period; is the average value of the time derivative of the system output voltage over the switching period; N k is the primary-to-secondary turns ratio of the transformer; L k is the output filter inductance of the kth module; R k is the equivalent load of the module; C k is the output capacitance of the kth module; i Lk is the output current of the kth module; v o is the system output voltage; v ink is the input voltage of the kth module; D ek is the effective duty cycle of the kth module.

5. The method of claim 1, wherein the ISOP converter is a high-voltage sensorless accurate voltage sharing control method, characterized in that, The method comprises the following steps: S21, replacing the input voltage and the output resistance with a parameter identification value to be solved according to the state equation of the current module, determining a parameter identification initial value, and establishing a reference equation; S22, selecting a proportional coefficient and an integral coefficient based on the response speed requirement, and determining a complex frequency domain of an adaptive approach rate by using a Lyapunov function, which is used for updating the parameter identification value; S23, obtaining an output voltage error and an output current error by comparing the system output voltage, the output current of each module and the corresponding values in the reference equation, and updating the parameter identification value based on the adaptive controller until the error converges to zero. The parameter identification initial value comprises an input voltage identification initial value and an output resistance identification initial value, and the parameter identification value comprises an input voltage identification value and an output resistance identification value.

6. The method of claim 5, wherein the ISOP converter is a high-voltage sensorless accurate voltage sharing control method, characterized in that, The expression of the complex frequency domain of the adaptive approach rate is: ； In the formula, is the output resistance identification value; R k (0) is the initial value of output resistance identification; K PRk and K Pvk are the proportional coefficient of output resistance identification and the proportional coefficient of input voltage identification, respectively; s is a complex variable; e uk is the output voltage error of the kth module; is the estimated value of system output voltage; is the input voltage identification value; V ink (0) is the initial value of input voltage identification; K IRk and K Ivk are the integral coefficient of output resistance identification and the integral coefficient of input voltage identification, respectively; e ik is the output current error of the kth module; C k is the output capacitance of the kth module; L k is the output filter inductance of the kth module.

7. The method of claim 5, wherein the ISOP converter is a high-voltage sensorless accurate voltage sharing control method, characterized in that, The output voltage error and the output current error are obtained by comparing the system output voltage, the output current of each module and the corresponding values in the reference equation, and the parameter identification value is updated based on the adaptive controller until the error converges to zero, comprising: S231, based on the actual output of the system, the output voltage and the output current of each module are obtained, and compared with the corresponding output voltage value and output current value in the reference equation; S232, according to the comparison result, the output voltage error and the output current error of each module are calculated, and the calculation result is input into the adaptive controller; S233, using the adaptive controller, the updated input voltage identification value and the output resistance identification value are output, and the error is made to converge to zero through multiple iterations.

8. The method of claim 1, wherein the ISOP converter is a high-voltage sensorless accurate voltage sharing control method, characterized in that, The product of the input voltage identification value and the feedforward coefficient is combined with the output voltage reference value, and the duty cycle signal is output through the voltage compensator and the current compensator, and the drive signal is generated to control the on-off of the switch tube, comprising: S31, multiply the input voltage identification value by the feedforward coefficient, add the output voltage reference value as a new reference value, and subtract the output voltage sampling value after the input voltage compensator; S32, the output of the voltage compensator is subtracted from the output current sampling value and input into the current compensator to obtain the duty cycle signal; S33, based on the duty cycle signal output by the current compensator, the drive signal is generated through pulse width modulation control to control the on-off of the switch tube.

9. The method of claim 1, wherein the ISOP converter is a high-voltage sensorless accurate voltage sharing control method, characterized in that, The input signal of the voltage compensator is the product of the input voltage identification value and the feedforward coefficient and the sum of the output voltage; The output signal of the voltage compensator is the reference value of the output current; The output signal of the current compensator is the module duty cycle, and the module drive signal is generated by intersecting with the sawtooth wave.

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