Predictive control method and system for three-port DC-DC converter

Abstract

The invention provides a prediction control method and system for a three-port DC-DC converter, and the method comprises the steps: solving a transmission relation between a current and a phase shift angle based on the structure parameters of the three-port DC-DC converter; a feedforward decoupling network is adopted, and a decoupled voltage ring is obtained through the transfer relation between the current and the phase shift angle; performing predictive control by adopting a predictive controller based on the output voltage of the decoupled voltage loop; according to the three-port DC-DC converter, the feed-forward decoupling network is adopted, decoupling control of the three-port DC-DC converter is achieved through decoupling of the transfer relation between the current and the phase shift angle, the decoupled voltage ring is obtained, and when prediction control is conducted on the decoupled voltage ring through the prediction controller, balance control over the load voltage and the power flow can be achieved; and better dynamic characteristics are obtained, so that smaller voltage fluctuation is obtained at the moment of load switching, and the efficiency of the whole machine is improved.

Description

Technical Field

[0001] The patent application of the present invention belongs to the technical field of DC-DC converters, and specifically relates to a predictive control method and system for a three-port DC-DC converter. Background Art

[0002] In the prior art, there are related designs for specific circuit models, but in actual applications, there are many factors that affect the final effect of power electronic devices. For example, the relevant performance of the device drifts with the change of temperature, and the impedance characteristics of the magnetic components at different frequencies have corresponding changes, which will affect the output effect of the converter.

[0003] Most of the existing technical solutions adopt proportional-integral control, which determines the current control input according to the deviation between the measured value output by the converter at the current moment and the last moment and the set reference value.

[0004] At present, there are PI (Proportional-Integral) control methods, zero-pole compensation methods, etc. for the control of isolated three-port DC-DC (Direct Current-Direct Current) converters. In the proportional-integral control and zero-pole correction methods, the small signal transfer function of the isolated three-port converter is used as a model to compensate for the zero-pole of the system, but when the load is switched, there is a problem of excessive voltage overshoot fluctuation. Summary of the invention

[0005] In order to overcome the above-mentioned deficiencies of the prior art, the present invention patent application proposes a predictive control method for a three-port DC-DC converter, comprising:

[0006] Based on the structural parameters of the three-port DC-DC converter, the transfer relationship between current and phase shift angle is obtained;

[0007] A feedforward decoupling network is used to obtain a decoupled voltage loop through the transmission relationship between the current and the phase shift angle;

[0008] Based on the output voltage of the decoupled voltage loop, a predictive controller is used to perform predictive control.

[0009] Preferably, obtaining the transfer relationship between current and phase shift angle based on the structural parameters of the three-port DC-DC converter includes:

[0010] According to the topological structure parameters of the three-port DC-DC converter, an equivalent circuit model of the three-port DC-DC converter is constructed;

[0011] Calculating the average current of the ports in the three-port DC-DC converter by using the three-port DC-DC converter equivalent circuit model; the average current of the ports includes: the average current of port 1, the average current of port 2 and the average current of port 3;

[0012] Based on the differential of the average current of port 1 and the differential of the average current of port 3, the partial derivatives of the differential of the phase shift angle between port 1 and port 2 and the differential of the phase shift angle between port 1 and port 3 are respectively calculated to obtain the transfer relationship between the current and the phase shift angle;

[0013] Among them, the structural parameters include at least one or more of the following: the switching tube of the converter, the voltage of each port, the current of each port, the transformer ratio of each port, the capacitance of each port, the sum of the inductance and leakage inductance connected in series to the first winding, the sum of the inductance and leakage inductance connected in series to the second winding, and the sum of the inductance and leakage inductance connected in series to the third winding.

[0014] Preferably, constructing an equivalent circuit model of a three-port DC-DC converter according to the topological structure parameters of the three-port DC-DC converter comprises:

[0015] The transformer in the three-port DC-DC converter topology is set as an ideal transformer and the excitation inductance is ignored, and then a provisional three-port DC-DC converter equivalent circuit model is constructed according to the topology parameters of the three-port DC-DC converter; the provisional three-port DC-DC converter equivalent circuit model includes port 1, port 2, port 3 and an inductor network;

[0016] The port 2 and the port 3 of the provisional three-port DC-DC converter equivalent circuit model are converted to the port 1, and the inductor network is transformed into a star-delta circuit to obtain the three-port DC-DC converter equivalent circuit model.

[0017] Preferably, the expression of the transmission relationship between the current and the phase shift angle is as follows:

[0018]

[0019] Where, ΔI1 is the differential of the average current at port 1, ΔI3 is the differential of the average current at port 3, and G 11 , G 12 , G 21 , G 22 are all intermediate variables. is the differential of the phase shift angle between port 1 and port 2, is the differential of the phase shift angle between port 1 and port 3.

[0020] Preferably, the feedforward decoupling network comprises a feedforward decoupling network H 12 and the feedforward decoupling network H 21The feedforward decoupling network is used to obtain a decoupled voltage loop through the transmission relationship between the current and the phase shift angle, including:

[0021] The differential of the phase shift angle between port 1 and port 2 is applied to the feedforward decoupling network H 21 , and obtain the corresponding coupling variables;

[0022] At the same time, the differential of the phase shift angle between port 1 and port 3 acts on the feedforward decoupling network H 12 , and obtain the corresponding coupling variables;

[0023] Applying the two coupling variables to the transfer relationship between the current and the phase shift angle to obtain a decoupled transfer relationship between the current and the phase shift angle;

[0024] According to the transmission relationship between the decoupled current and the phase shift angle, a decoupled voltage loop is obtained.

[0025] Preferably, the output voltage of the decoupled voltage loop is controlled by using a predictive controller, comprising:

[0026] Based on the output voltage of the decoupled voltage loop, the optimal shift phase is obtained through the prediction model of the prediction controller;

[0027] The optimal phase shift angle is applied to the transmission relationship between the decoupled current and the phase shift angle to complete the predictive control.

[0028] Preferably, the construction of the prediction model includes:

[0029] Based on the relationship between the output capacitance of port 3 and the load resistance circuit, capacitance voltage and current in the main circuit topology mathematical model, the data relationship expression is obtained;

[0030] According to the data relationship expression, forward difference is used to perform discretization to obtain the expression of the prediction model, thereby completing the construction of the prediction model.

[0031] Preferably, the expression of the prediction model is as follows:

[0032]

[0033] Wherein, V3(k+1) is the square wave voltage of port 3 at time k+1, V1(k) is the square wave voltage of port 1 at time k, is the phase shift angle between port 1 and port 2 at time k, f s is the switching frequency of the converter, C3 is the capacitor of port 3, L3 is the sum of the inductance and leakage inductance connected in series to the third winding, T sis the switching period of the converter, V3(k) is the square wave voltage of port 3 at time k, and R0 is the load resistance.

[0034] Based on the same inventive concept, the patent application of the present invention also provides a predictive control system for a three-port DC-DC converter, including: a transfer relationship module, a decoupling voltage loop module and a predictive control module;

[0035] The transfer relationship module is used to obtain the transfer relationship between the current and the phase shift angle based on the structural parameters of the three-port DC-DC converter;

[0036] The decoupling voltage loop module is used to obtain a decoupled voltage loop by using a feedforward decoupling network through the transmission relationship between the current and the phase shift angle;

[0037] The prediction control module is used to perform prediction control using a prediction controller based on the output voltage of the decoupled voltage loop.

[0038] Preferably, the transfer relationship module includes:

[0039] An equivalent circuit model building submodule is used to build an equivalent circuit model of a three-port DC-DC converter according to topological structure parameters of the three-port DC-DC converter;

[0040] The port average current calculation submodule is used to calculate the port average current in the three-port DC-DC converter through the three-port DC-DC converter equivalent circuit model; the port average current includes: port 1 average current, port 2 average current and port 3 average current;

[0041] The current and phase shift angle transfer relationship submodule is used to obtain the partial derivative of the differential of the phase shift angle between port 1 and port 2 and the differential of the phase shift angle between port 1 and port 3 based on the differential of the average current of port 1 and the differential of the average current of port 3, so as to obtain the transfer relationship between the current and the phase shift angle;

[0042] Among them, the structural parameters include at least one or more of the following: the switching tube of the converter, the voltage of each port, the current of each port, the transformer ratio of each port, the capacitance of each port, the sum of the inductance and leakage inductance connected in series to the first winding, the sum of the inductance and leakage inductance connected in series to the second winding, and the sum of the inductance and leakage inductance connected in series to the third winding.

[0043] Preferably, the equivalent circuit model construction submodule is specifically used for:

[0044] The transformer in the three-port DC-DC converter topology is set as an ideal transformer and the excitation inductance is ignored, and then a provisional three-port DC-DC converter equivalent circuit model is constructed according to the topology parameters of the three-port DC-DC converter; the provisional three-port DC-DC converter equivalent circuit model includes port 1, port 2, port 3 and an inductor network;

[0045] The port 2 and the port 3 of the provisional three-port DC-DC converter equivalent circuit model are converted to the port 1, and the inductor network is transformed into a star-delta circuit to obtain the three-port DC-DC converter equivalent circuit model.

[0046] Preferably, the expression of the transmission relationship between the current and the phase shift angle is as follows:

[0047]

[0048] Where, ΔI1 is the differential of the average current at port 1, ΔI3 is the differential of the average current at port 3, and G 11 , G 12 , G 21 , G 22 are all intermediate variables. is the differential of the phase shift angle between port 1 and port 2, is the differential of the phase shift angle between port 1 and port 3.

[0049] Preferably, the feedforward decoupling network comprises a feedforward decoupling network H 12 and the feedforward decoupling network H 21 ; The decoupling voltage loop module comprises:

[0050] The first coupling variable determination submodule is used to apply the differential of the phase shift angle between the port 1 and the port 2 to the feedforward decoupling network H 21 , and obtain the corresponding coupling variables;

[0051] The second coupling variable determination submodule is used to simultaneously apply the differential of the phase shift angle between the port 1 and the port 3 to the feedforward decoupling network H 12 , and obtain the corresponding coupling variables;

[0052] A decoupled current and phase shift angle transfer relationship submodule, used for applying the two coupling variables to the transfer relationship between the current and the phase shift angle to obtain a decoupled current and phase shift angle transfer relationship;

[0053] The decoupled voltage loop determination submodule is used to obtain the decoupled voltage loop according to the transmission relationship between the decoupled current and the phase shift angle.

[0054] Preferably, the prediction control module comprises:

[0055] An optimal shift phase ratio determination submodule is used to obtain an optimal shift phase ratio through a prediction model of a prediction controller based on the output voltage of the decoupled voltage loop;

[0056] The predictive control submodule is used to apply the optimal phase shift angle to the transmission relationship between the decoupled current and the phase shift angle to complete the predictive control.

[0057] Preferably, the system further comprises: a prediction model building module, for:

[0058] Based on the relationship between the output capacitance of port 3 and the load resistance circuit, capacitance voltage and current in the main circuit topology mathematical model, the data relationship expression is obtained;

[0059] According to the data relationship expression, forward difference is used to perform discretization to obtain the expression of the prediction model, thereby completing the construction of the prediction model.

[0060] Preferably, the expression of the prediction model is as follows:

[0061]

[0062] Wherein, V3(k+1) is the square wave voltage of port 3 at time k+1, V1(k) is the square wave voltage of port 1 at time k, is the phase shift angle between port 1 and port 2 at time k, f s is the switching frequency of the converter, C3 is the capacitor of port 3, L3 is the sum of the inductance and leakage inductance connected in series to the third winding, T s is the switching period of the converter, V3(k) is the square wave voltage of port 3 at time k, and R0 is the load resistance.

[0063] Based on the same inventive concept, the present patent application also provides a computer device, including: one or more processors;

[0064] A memory for storing one or more programs;

[0065] When the one or more programs are executed by the one or more processors, the predictive control method of a three-port DC-DC converter as described above is implemented.

[0066] Based on the same inventive concept, the patent application of the present invention also provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed, a predictive control method for a three-port DC-DC converter as described above is implemented.

[0067] Compared with the closest prior art, the patent application of this invention has the following beneficial effects:

[0068] The patent application of the present invention provides a predictive control method and system for a three-port DC-DC converter, including: based on the structural parameters of the three-port DC-DC converter, obtaining the transfer relationship between the current and the phase shift angle; using a feedforward decoupling network, through the transfer relationship between the current and the phase shift angle, obtaining a decoupled voltage loop; based on the output voltage of the decoupled voltage loop, using a predictive controller to perform predictive control; the present invention uses a feedforward decoupling network to decouple the transfer relationship between the current and the phase shift angle to achieve decoupling control of the three-port DC-DC converter, obtain the decoupled voltage loop, and use a predictive controller to perform predictive control on the decoupled voltage loop, which can achieve balanced control of the load voltage and power flow, obtain better dynamic characteristics, and then obtain smaller voltage fluctuations at the moment of load switching, thereby improving the efficiency of the entire machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 A schematic flow chart of a predictive control method for a three-port DC-DC converter provided for the patent application of the present invention;

[0070] Figure 2 A schematic diagram of the main circuit topology of a three-port DC-DC converter provided for the patent application of the present invention;

[0071] Figure 3 A tentative three-port DC-DC converter equivalent circuit diagram provided for the patent application of the present invention;

[0072] Figure 4 A schematic diagram of an equivalent circuit of a three-port DC-DC converter provided for the patent application of the present invention;

[0073] Figure 5 A schematic diagram of a phase shift control waveform provided for the patent application of the present invention;

[0074] Figure 6 A control strategy block diagram provided for the patent application of this invention;

[0075] Figure 7 A schematic diagram of PI control output provided for the patent application of the present invention;

[0076] Figure 8 A schematic diagram of the predictive control output provided for the patent application of the present invention;

[0077] Fig. 9 The waveform diagram of instantaneous load switching during PI control provided in the patent application of the present invention;

[0078] Fig.10 A waveform diagram of instantaneous load switching during predictive control provided in the patent application of the present invention;

[0079] Fig.11A schematic diagram of a predictive control system for a three-port DC-DC converter provided for the patent application of the present invention;

[0080] Fig.12 A schematic structural diagram of an electronic device provided for the patent application of the present invention. DETAILED DESCRIPTION

[0081] The specific implementation methods of the patent application of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0082] Embodiment 1:

[0083] The present invention provides a predictive control method for a three-port DC-DC converter. Figure 1 As shown, including:

[0084] Step 1: Based on the structural parameters of the three-port DC-DC converter, the transfer relationship between current and phase shift angle is obtained;

[0085] Step 2: using a feedforward decoupling network to obtain a decoupled voltage loop through the transmission relationship between the current and the phase shift angle;

[0086] Step 3: Based on the output voltage of the decoupled voltage loop, a predictive controller is used to perform predictive control.

[0087] The above step 1, based on the structural parameters of the three-port DC-DC converter, obtains the transfer relationship between the current and the phase shift angle, including:

[0088] According to the topological structure parameters of the three-port DC-DC converter, an equivalent circuit model of the three-port DC-DC converter is constructed;

[0089] For example, the main circuit topology of the three-port DC-DC converter is as follows Figure 2 As shown, port 1 is connected to the DC power supply, port 2 is connected to the energy storage battery, and port 3 is connected to the load; the high-frequency transformer couples the three ports together, where S1~S 12 All are switch tubes of three-port DC-DC converters, V1 is the voltage of port 1, V2 is the voltage of port 2, V3 is the voltage of port 3, I1 is the current of port 1, I2 is the current of port 2, I3 is the current of port 3, N1 is the transformer ratio of port 1, N2 is the transformer ratio of port 2, N3 is the transformer ratio of port 3, C1 is the capacitance of port 1, C2 is the capacitance of port 2, C3 is the capacitance of port 3, L1 is the sum of the inductance and leakage inductance connected in series to the first winding, L2 is the sum of the inductance and leakage inductance connected in series to the second winding, and L3 is the sum of the inductance and leakage inductance connected in series to the third winding;

[0090] The main circuit design of the three-port DC-DC converter adopts a single phase shift control method. The upper and lower tubes of each port bridge arm are complementary turned on, the duty cycle is 0.5, and the phase shift angle between the two ports 1 and 2 is The phase shift angle between port 1 and port 3 is The midpoint voltage of the bridge arm is a standard square wave, so Figure 2 The main circuit topology of the three-port DC-DC converter is equivalent to Figure 3 The tentative three-port DC-DC converter equivalent circuit shown in FIG. 1 is a schematic diagram of a three-port DC-DC converter. In the schematic diagram, V1 is the voltage of port 1, V2 is the voltage of port 2, V3 is the voltage of port 3, L1 is the inductance of port 1, L2 is the inductance of port 2, L3 is the inductance of port 3, N1 is the transformer ratio of port 1, N2 is the transformer ratio of port 2, and N3 is the transformer ratio of port 3. The transformer in the tentative three-port DC-DC converter equivalent circuit model is an ideal transformer. The magnetizing inductance is much larger than the transformer leakage inductance. The magnetizing inductance is ignored. Therefore, Figure 3 Port 2 and port 3 are converted to port 1, and then the inductor network is transformed into a star-delta, which is equivalent to Figure 4 The circuit shown is used to analyze the energy transfer between ports.

[0091] Figure 4 The inductance in is given by the following formula:

[0092]

[0093] Among them, L 12 is the inductance between port 1 and port 2, L 13 is the inductance between port 1 and port 3, L 23 is the inductance between port 2 and port 3, L 1r is the equivalent inductance of port 1, L 2r is the equivalent inductance of port 2, L 3r is the equivalent inductance of port 3;

[0094] Figure 4 In the inductance formula, L 1r =L1

[0095] Where, L1 is the inductance of port 1;

[0096] Figure 4 In the inductance formula, L 2r as follows:

[0097]

[0098] Where N1 is the transformer ratio of port 1, N2 is the transformer ratio of port 2, and L2 is the inductance of port 2;

[0099] Figure 4 In the inductance formula, L 3r as follows:

[0100]

[0101] Where N1 is the transformer ratio of port 1, N3 is the transformer ratio of port 3, and L3 is the inductance of port 3;

[0102] The control method of the isolated three-port DC-DC converter is to use phase shifting to fix the PWM (Pulse Width Modulation) duty cycle of the driver. The two tubes in the same bridge arm of each port are complementary and their duty cycles are 50% respectively. The internal phase shift angle between the bridge arms is fixed to 180 degrees. The driving signals of the diagonal switch tubes are the same. There is a certain phase difference between the driving signals of the switch tubes at the corresponding positions between the two ports, namely the external phase shift angle. like Figure 5 The figure shows the phase shift control waveform, where V1 is the voltage of port 1, V2 is the voltage of port 2, and V3 is the voltage of port 3. The voltage at this time is in the form of a square wave. is the phase shift angle between port 1 and port 2, is the phase shift angle between port 1 and port 3, t is the time, when V1 leads V2, the phase shift angle Greater than 0.

[0103] Depend on Figure 4 The relationship between the power P1 of port 1, the power P2 of port 2, and the power P3 of port 3 is as follows:

[0104]

[0105] Where P1 is the power at port 1, P2 is the power at port 2, and P3 is the power at port 3. is the phase shift angle between port 1 and port 2, is the phase shift angle between port 1 and port 3, is the phase shift angle between port 2 and port 3, V 1r is the equivalent voltage of port 1, V 2r is the equivalent voltage of port 2, V 3r is the equivalent voltage of port 3, L 12 is the inductance between port 1 and port 2, L 13 is the inductance between port 1 and port 3, L 23 The inductance between port 2 and port 3, f is the switching frequency of the converter;

[0106] Among them, V 1r =V1

[0107] V2r The calculation formula is as follows:

[0108]

[0109] Where N1 is the transformer ratio of port 1, N2 is the transformer ratio of port 2, and V2 is the voltage of port 2;

[0110] V 3r The calculation formula is as follows:

[0111]

[0112] Among them, N1 is the transformer ratio of port 1, N3 is the transformer ratio of port 3, and V3 is the voltage of port 3.

[0113] Calculating the average current of the ports in the three-port DC-DC converter by using the three-port DC-DC converter equivalent circuit model; the average current of the ports includes: the average current of port 1, the average current of port 2 and the average current of port 3;

[0114] For example, the two ends of the relationship between the power P1 of port 1, the power P2 of port 2, and the power P3 of port 3 in the equivalent circuit model of the three-port DC-DC converter are divided by the port voltage corresponding to the port power, and the average current of the port is as follows:

[0115]

[0116] Among them, I1 is the average current of port 1, I2 is the average current of port 2, and I3 is the average current of port 3. is the phase shift angle between port 1 and port 2, is the phase shift angle between port 1 and port 3, V 1r is the equivalent voltage of port 1, V 2r is the equivalent voltage of port 2, V 3r is the equivalent voltage of port 3, L 12 is the inductance between port 1 and port 2, L 13 is the inductance between port 1 and port 3, L 23 The inductance between port 2 and port 3, f is the switching frequency of the converter.

[0117] Based on the differential of the average current of port 1 and the differential of the average current of port 3, the partial derivatives of the differential of the phase shift angle between port 1 and port 2 and the differential of the phase shift angle between port 1 and port 3 are respectively calculated to obtain the transfer relationship between the current and the phase shift angle;

[0118] Among them, the structural parameters include at least one or more of the following: the switching tube of the converter, the voltage of each port, the current of each port, the transformer ratio of each port, the capacitance of each port, the sum of the inductance and leakage inductance connected in series to the first winding, the sum of the inductance and leakage inductance connected in series to the second winding, and the sum of the inductance and leakage inductance connected in series to the third winding.

[0119] In one implementation, constructing an equivalent circuit model of a three-port DC-DC converter according to the topological structure parameters of the three-port DC-DC converter includes:

[0120] The transformer in the three-port DC-DC converter topology is set as an ideal transformer and the excitation inductance is ignored, and then a provisional three-port DC-DC converter equivalent circuit model is constructed according to the topology parameters of the three-port DC-DC converter; the provisional three-port DC-DC converter equivalent circuit model includes port 1, port 2, port 3 and an inductor network;

[0121] The port 2 and the port 3 of the provisional three-port DC-DC converter equivalent circuit model are converted to the port 1, and the inductor network is transformed into a star-delta circuit to obtain the three-port DC-DC converter equivalent circuit model.

[0122] In one implementation, the expression of the transmission relationship between the current and the phase shift angle is as follows:

[0123]

[0124] Where, ΔI1 is the differential of the average current at port 1, ΔI3 is the differential of the average current at port 3, and G 11 , G 12 , G 21 , G 22 are all intermediate variables. is the differential of the phase shift angle between port 1 and port 2, is the differential of the phase shift angle between port 1 and port 3.

[0125] For example, the calculation formula of the intermediate variable in the expression of the transmission relationship between current and phase shift angle is as follows:

[0126]

[0127] Among them, G 11 , G 12 , G 21 , G 22 are all intermediate variables. is the phase shift angle between port 1 and port 2, is the phase shift angle between port 1 and port 3, is the phase shift angle between port 2 and port 3, V 1ris the equivalent voltage of port 1, V 2r is the equivalent voltage of port 2, V 3r is the equivalent voltage of port 3, L 12 is the inductance between port 1 and port 2, L 13 is the inductance between port 1 and port 3, L 23 The inductance between port 2 and port 3, f is the switching frequency of the converter, N1 is the transformer ratio of port 1, N2 is the transformer ratio of port 2, and N3 is the transformer ratio of port 3; the present invention analyzes the working principle and working mode of the isolated three-port DC-DC converter, derives the power transmission expression of the three-port converter on the basis of the power calculation of the dual-active bridge DC-DC converter, studies the equivalent circuit model of the three-port DC-DC converter by using the average current method, and obtains the transmission relationship between the current and the phase shift angle required for subsequent decoupling.

[0128] The feedforward decoupling network described in step 2 above includes a feedforward decoupling network H 12 and the feedforward decoupling network H 21 The feedforward decoupling network is used to obtain a decoupled voltage loop through the transmission relationship between the current and the phase shift angle, including:

[0129] The differential of the phase shift angle between port 1 and port 2 is applied to the feedforward decoupling network H 21 , and obtain the corresponding coupling variables;

[0130] At the same time, the differential of the phase shift angle between port 1 and port 3 acts on the feedforward decoupling network H 12 , and obtain the corresponding coupling variables;

[0131] Applying the two coupling variables to the transfer relationship between the current and the phase shift angle to obtain a decoupled transfer relationship between the current and the phase shift angle;

[0132] According to the transmission relationship between the decoupled current and the phase shift angle, a decoupled voltage loop is obtained.

[0133] For example, the transmission relationship between current and phase shift angle is eliminated by feedforward decoupling network. For ΔI1, The influence of mutual coupling of ΔI3, the transmission relationship between current and phase shift angle after decoupling corresponds to Figure 6 In the control strategy block diagram shown in the figure, H 12 With H 21 It is a feedforward decoupling network, satisfying the following formula:

[0134]

[0135] Among them, G 11 , G12 , G 21 , G 22 are all intermediate variables. is the differential of the phase shift angle between port 1 and port 2, is the differential of the phase shift angle between port 1 and port 3, H 12 , H 21 All are feed-forward decoupling networks;

[0136] Through the feedforward decoupling network, the control variables are first calculated to obtain the coupled variables, which are added to the control strategy to achieve G 12 With G 21 The transmission relationship between the current and the phase shift angle after decoupling is as follows:

[0137]

[0138] Where ΔI1 is the differential of the average current at port 1, ΔI3 is the differential of the average current at port 3, is the differential of the phase shift angle between port 1 and port 2, is the differential of the phase shift angle between port 1 and port 3, G 11 , G 22 They are all intermediate variables. In the present invention, since there is cross-coupling between the ports, before decoupling, there is a coupled voltage loop plus a coupled current loop. Therefore, it is necessary to decouple the transmission relationship between the current and the phase shift angle through a feedforward decoupling network to realize the feedforward decoupling control of the isolated three-port converter. After decoupling, there is a separate voltage loop plus a separate current loop, which provides a decoupled voltage loop for subsequent predictive control.

[0139] The above step 3 uses a predictive controller to perform predictive control based on the output voltage of the decoupled voltage loop, including:

[0140] Based on the output voltage of the decoupled voltage loop, the optimal shift phase is obtained through the prediction model of the prediction controller;

[0141] For example, in the prediction model of the prediction controller, the predicted output voltage value is made equal to the reference voltage value. At this time, the corresponding shift phase ratio is the optimal shift phase ratio. The calculation formula of the optimal shift phase ratio is as follows:

[0142]

[0143] in, is the optimal phase shift angle, which is also the phase shift angle between port 1 and port 2 at time k, f is the switching frequency of the converter, L3 is the inductance of port 3, I0(k) is the load current at time k, C3 is the capacitance of port 3, V 3refis the expected output voltage reference value, V3(k+1) is the voltage of port 3 at time k+1, and V3(k) is the voltage of port 3 at time k. The optimal phase shift angle is applied to the transmission relationship between the decoupled current and the phase shift angle to complete the predictive control.

[0144] For example, the output of the voltage loop, that is, the output voltage at the load end, is predicted and corrected by a predictive controller and controlled by a predictive controller; a simulation model is built using Matlab, and the converter is verified. By adding the shift phase into the control strategy, optimal control of the converter can be achieved.

[0145] In one implementation, the construction of the prediction model includes:

[0146] Based on the relationship between the output capacitance of port 3 and the load resistance circuit, capacitance voltage and current in the main circuit topology mathematical model, the data relationship expression is obtained;

[0147] According to the data relationship expression, forward difference is used to perform discretization to obtain the expression of the prediction model, thereby completing the construction of the prediction model.

[0148] For example, Kirchhoff's current law and Kirchhoff's voltage law are used to list the circuit equations for the output capacitor and load resistance of port 3, and based on the relationship between capacitor voltage and current, the following relationship expression is obtained:

[0149]

[0150] Where C3 is the capacitance of port 3, V3 is the voltage of port 3, V1 is the voltage of port 1, is the phase shift angle between port 1 and port 2, L3 is the sum of the inductance and leakage inductance connected in series to the third winding, R0 is the load resistance, and f is the switching frequency of the converter;

[0151] The relational expression of the above formula is discretized by forward difference, and the following formula is obtained:

[0152]

[0153] Where C3 is the capacitance of port 3, V3(k+1) is the voltage of port 3 at time k+1, V3(k) is the voltage of port 3 at time k, T s is the switching period of the converter, V1(k) is the voltage of port 1 at time k, is the phase shift angle between port 1 and port 2 at time k, L3 is the sum of the inductance connected in series to the third winding and the leakage inductance, R0 is the load resistance, and f is the switching frequency of the converter;

[0154] The discretized formulas are sorted out to obtain the expression of the prediction model.

[0155] In one implementation, the expression of the prediction model is as follows:

[0156]

[0157] Wherein, V3(k+1) is the square wave voltage of port 3 at time k+1, V1(k) is the square wave voltage of port 1 at time k, is the phase shift angle between port 1 and port 2 at time k, f s is the switching frequency of the converter, C3 is the capacitor of port 3, L3 is the sum of the inductance and leakage inductance connected in series to the third winding, T s is the switching period of the converter, V3(k) is the square wave voltage of port 3 at time k, and R0 is the load resistance; in the traditional proportional integral control, the traditional PI control and zero-pole correction method, the small signal transfer function of the isolated three-port converter is used as a model to compensate the zero-pole of the system, but when the load is switched, there is a problem of excessive voltage overshoot fluctuation. The present invention adopts the transfer relationship between the decoupled current and the phase shift angle combined with the predictive control method to achieve balanced control of the load voltage and power flow. It can be seen from simulation verification that compared with traditional control, the predictive control has stronger flexibility and adaptability, and can also improve the response speed and recovery ability of the system, such as Figure 7 The PI control output of the prior art is shown as follows: Figure 8 The figure shows the output of the predictive control of the present invention. It can be seen from the figure that compared with the predictive control of the present invention, the PI control has obvious overshoot at the initial startup, such as Fig. 9 The waveform diagram of load instantaneous switching under PI control is shown as Fig.10 The waveform diagram of instantaneous load switching during the predictive control of the present invention is shown. It can be seen from the figure that the predictive control of the present invention is more stable during dynamic changes; the decoupled voltage loop can achieve independent control, so the predictive control method is adopted to control the voltage loop to achieve optimization under load fluctuations; the present invention first establishes a mathematical model for the entire main circuit topology to obtain the transmission relationship between current and phase shift angle, and through the transmission relationship between current and phase shift angle, the feedforward decoupling method is used to achieve independent control of the power of each port. On this basis, the voltage loop is predictively controlled to obtain better dynamic characteristics, obtain smaller voltage fluctuations at the moment of load switching, and improve the efficiency of the whole machine.

[0158] Embodiment 2:

[0159] Based on the same inventive concept, the present invention patent application also provides a predictive control system for a three-port DC-DC converter such as Fig.11As shown, it includes: a transfer relationship module, a decoupling voltage loop module and a predictive control module;

[0160] The transfer relationship module is used to obtain the transfer relationship between the current and the phase shift angle based on the structural parameters of the three-port DC-DC converter;

[0161] The decoupling voltage loop module is used to obtain a decoupled voltage loop by using a feedforward decoupling network through the transmission relationship between the current and the phase shift angle;

[0162] The prediction control module is used to perform prediction control using a prediction controller based on the output voltage of the decoupled voltage loop.

[0163] Preferably, the transfer relationship module includes:

[0164] An equivalent circuit model building submodule is used to build an equivalent circuit model of a three-port DC-DC converter according to topological structure parameters of the three-port DC-DC converter;

[0165] The port average current calculation submodule is used to calculate the port average current in the three-port DC-DC converter through the three-port DC-DC converter equivalent circuit model; the port average current includes: port 1 average current, port 2 average current and port 3 average current;

[0166] The current and phase shift angle transfer relationship submodule is used to obtain the partial derivative of the differential of the phase shift angle between port 1 and port 2 and the differential of the phase shift angle between port 1 and port 3 based on the differential of the average current of port 1 and the differential of the average current of port 3, so as to obtain the transfer relationship between the current and the phase shift angle;

[0167] Among them, the structural parameters include at least one or more of the following: the switching tube of the converter, the voltage of each port, the current of each port, the transformer ratio of each port, the capacitance of each port, the sum of the inductance and leakage inductance connected in series to the first winding, the sum of the inductance and leakage inductance connected in series to the second winding, and the sum of the inductance and leakage inductance connected in series to the third winding.

[0168] Preferably, the equivalent circuit model construction submodule is specifically used for:

[0169] The transformer in the three-port DC-DC converter topology is set as an ideal transformer and the excitation inductance is ignored, and then a provisional three-port DC-DC converter equivalent circuit model is constructed according to the topology parameters of the three-port DC-DC converter; the provisional three-port DC-DC converter equivalent circuit model includes port 1, port 2, port 3 and an inductor network;

[0170] The port 2 and the port 3 of the provisional three-port DC-DC converter equivalent circuit model are converted to the port 1, and the inductor network is transformed into a star-delta circuit to obtain the three-port DC-DC converter equivalent circuit model.

[0171] Preferably, the expression of the transmission relationship between the current and the phase shift angle is as follows:

[0172]

[0173] Where, ΔI1 is the differential of the average current at port 1, ΔI3 is the differential of the average current at port 3, and G 11 , G 12 , G 21 , G 22 are all intermediate variables. is the differential of the phase shift angle between port 1 and port 2, is the differential of the phase shift angle between port 1 and port 3.

[0174] Preferably, the feedforward decoupling network comprises a feedforward decoupling network H 12 and the feedforward decoupling network H 21 ; The decoupling voltage loop module comprises:

[0175] The first coupling variable determination submodule is used to apply the differential of the phase shift angle between the port 1 and the port 2 to the feedforward decoupling network H 21 , and obtain the corresponding coupling variables;

[0176] The second coupling variable determination submodule is used to simultaneously apply the differential of the phase shift angle between the port 1 and the port 3 to the feedforward decoupling network H 12 , and obtain the corresponding coupling variables;

[0177] A decoupled current and phase shift angle transfer relationship submodule, used for applying the two coupling variables to the transfer relationship between the current and the phase shift angle to obtain a decoupled current and phase shift angle transfer relationship;

[0178] The decoupled voltage loop determination submodule is used to obtain the decoupled voltage loop according to the transmission relationship between the decoupled current and the phase shift angle.

[0179] Preferably, the prediction control module comprises:

[0180] An optimal shift phase ratio determination submodule is used to obtain an optimal shift phase ratio through a prediction model of a prediction controller based on the output voltage of the decoupled voltage loop;

[0181] The predictive control submodule is used to apply the optimal phase shift angle to the transmission relationship between the decoupled current and the phase shift angle to complete the predictive control.

[0182] Preferably, the system further comprises: a prediction model building module, for:

[0183] Based on the relationship between the output capacitance of port 3 and the load resistance circuit, capacitance voltage and current in the main circuit topology mathematical model, the data relationship expression is obtained;

[0184] According to the data relationship expression, forward difference is used to perform discretization to obtain the expression of the prediction model, thereby completing the construction of the prediction model.

[0185] Preferably, the expression of the prediction model is as follows:

[0186]

[0187] Wherein, V3(k+1) is the square wave voltage of port 3 at time k+1, V1(k) is the square wave voltage of port 1 at time k, is the phase shift angle between port 1 and port 2 at time k, f s is the switching frequency of the converter, C3 is the capacitor of port 3, L3 is the sum of the inductance and leakage inductance connected in series to the third winding, T s is the switching period of the converter, V3(k) is the square wave voltage of port 3 at time k, and R0 is the load resistance.

[0188] Example 3

[0189] like Fig.12 As shown, the present invention also provides an electronic device, which may be a computer device, a single-chip device, an intelligent mobile device, etc. The electronic device in this embodiment may include a processor, a memory, a transceiver component, etc. The memory, the processor, and the transceiver component are connected via a bus; the memory may be used to store an execution program, and an exemplary execution program may include instructions; the processor is used to execute the instructions stored in the memory. The memory may also be used to store data, which may be called and / or modified when the instructions are executed.

[0190] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in a storage medium to implement a corresponding method flow or a corresponding function, so as to implement the steps of a predictive control method for a three-port DC-DC converter in the above embodiment.

[0191] Example 4

[0192] Based on the same inventive concept, the present invention also provides a readable storage medium, specifically an electronic device readable storage medium (Memory), the electronic device readable storage medium is a memory device in the electronic device, used to store programs and data. It can be understood that the storage medium here can include both the built-in storage medium in the electronic device and the extended storage medium supported by the electronic device. The storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and these instructions can be one or more execution programs (including program codes). It should be noted that the storage medium here can be a high-speed RAM memory or a non-volatile memory (non-volatile memory), such as at least one disk storage. The processor loads and executes one or more instructions stored in the storage medium, which can implement the steps of a predictive control method for a three-port DC-DC converter in the above embodiment.

[0193] It should be understood by those skilled in the art that the embodiments of the present invention patent application can be provided as methods, systems, or computer program products. Therefore, the present invention patent application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention patent application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0194] The present invention patent application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present invention patent application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0195] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0196] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0197] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the patent application of the present invention rather than to limit its protection scope. Although the patent application of the present invention is described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that after reading the patent application of the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the application, but these changes, modifications or equivalent substitutions are all within the protection scope of the claims to be approved.

Claims

1. A predictive control method for a three-port DC-DC converter, characterized in that: include: Based on the structural parameters of the three-port DC-DC converter, the transfer relationship between current and phase shift angle is obtained; A feedforward decoupling network is used to obtain a decoupled voltage loop through the transmission relationship between the current and the phase shift angle; Based on the output voltage of the decoupled voltage loop, a predictive controller is used to perform predictive control.

2. The method according to claim 1, characterized in that The method of obtaining the transfer relationship between the current and the phase shift angle based on the structural parameters of the three-port DC-DC converter includes: According to the topological structure parameters of the three-port DC-DC converter, an equivalent circuit model of the three-port DC-DC converter is constructed; Calculating the average current of the ports in the three-port DC-DC converter by using the three-port DC-DC converter equivalent circuit model; the average current of the ports includes: the average current of port 1, the average current of port 2 and the average current of port 3; Based on the differential of the average current of port 1 and the differential of the average current of port 3, the partial derivatives of the differential of the phase shift angle between port 1 and port 2 and the differential of the phase shift angle between port 1 and port 3 are respectively calculated to obtain the transfer relationship between the current and the phase shift angle; Among them, the structural parameters include at least one or more of the following: the switching tube of the converter, the voltage of each port, the current of each port, the transformer ratio of each port, the capacitance of each port, the sum of the inductance and leakage inductance connected in series to the first winding, the sum of the inductance and leakage inductance connected in series to the second winding, and the sum of the inductance and leakage inductance connected in series to the third winding.

3. The method according to claim 2, characterized in that The method of constructing an equivalent circuit model of a three-port DC-DC converter according to the topological structure parameters of the three-port DC-DC converter comprises: The transformer in the three-port DC-DC converter topology is set as an ideal transformer and the excitation inductance is ignored, and then a provisional three-port DC-DC converter equivalent circuit model is constructed according to the topology parameters of the three-port DC-DC converter; the provisional three-port DC-DC converter equivalent circuit model includes port 1, port 2, port 3 and an inductor network; The port 2 and the port 3 of the provisional three-port DC-DC converter equivalent circuit model are converted to the port 1, and the inductor network is transformed into a star-delta circuit to obtain the three-port DC-DC converter equivalent circuit model.

4. The method according to claim 2, characterized in that The expression of the transmission relationship between the current and the phase shift angle is as follows: Where, ΔI1 is the differential of the average current at port 1, ΔI3 is the differential of the average current at port 3, and G 11 , G 12 , G 21 , G 22 are all intermediate variables. is the differential of the phase shift angle between port 1 and port 2, is the differential of the phase shift angle between port 1 and port 3.

5. The method according to claim 2, characterized in that The feedforward decoupling network includes a feedforward decoupling network H 12 and the feedforward decoupling network H 21 The feedforward decoupling network is used to obtain a decoupled voltage loop through the transmission relationship between the current and the phase shift angle, including: The differential of the phase shift angle between port 1 and port 2 is applied to the feedforward decoupling network H 21 , and obtain the corresponding coupling variables; At the same time, the differential of the phase shift angle between port 1 and port 3 acts on the feedforward decoupling network H 12 , and obtain the corresponding coupling variables; Applying the two coupling variables to the transfer relationship between the current and the phase shift angle to obtain a decoupled transfer relationship between the current and the phase shift angle; According to the transmission relationship between the decoupled current and the phase shift angle, a decoupled voltage loop is obtained.

6. The method according to claim 5, characterized in that The predictive control is performed by using a predictive controller based on the output voltage of the decoupled voltage loop, including: Based on the output voltage of the decoupled voltage loop, the optimal shift phase is obtained through the prediction model of the prediction controller; The optimal phase shift angle is applied to the transmission relationship between the decoupled current and the phase shift angle to complete the predictive control.

7. The method according to claim 6, characterized in that The construction of the prediction model includes: Based on the relationship between the output capacitance of port 3 and the load resistance circuit, capacitance voltage and current in the main circuit topology mathematical model, the data relationship expression is obtained; According to the data relationship expression, forward difference is used to perform discretization to obtain the expression of the prediction model, thereby completing the construction of the prediction model.

8. The method according to claim 7, characterized in that The expression of the prediction model is as follows: Wherein, V3(k+1) is the square wave voltage of port 3 at time k+1, V1(k) is the square wave voltage of port 1 at time k, is the phase shift angle between port 1 and port 2 at time k, f s is the switching frequency of the converter, C3 is the capacitor of port 3, L3 is the sum of the inductance and leakage inductance connected in series to the third winding, T s is the switching period of the converter, V3(k) is the square wave voltage of port 3 at time k, and R0 is the load resistance.

9. A predictive control system for a three-port DC-DC converter, characterized in that: include: transfer relationship module, decoupled voltage loop module and predictive control module; The transfer relationship module is used to obtain the transfer relationship between the current and the phase shift angle based on the structural parameters of the three-port DC-DC converter; The decoupling voltage loop module is used to obtain a decoupled voltage loop by using a feedforward decoupling network through the transmission relationship between the current and the phase shift angle; The prediction control module is used to perform prediction control using a prediction controller based on the output voltage of the decoupled voltage loop.

10. The system according to claim 9, characterized in that The transfer relationship module includes: An equivalent circuit model building submodule is used to build an equivalent circuit model of a three-port DC-DC converter according to topological structure parameters of the three-port DC-DC converter; The port average current calculation submodule is used to calculate the port average current in the three-port DC-DC converter through the three-port DC-DC converter equivalent circuit model; the port average current includes: port 1 average current, port 2 average current and port 3 average current; The current and phase shift angle transfer relationship submodule is used to obtain the partial derivative of the differential of the phase shift angle between port 1 and port 2 and the differential of the phase shift angle between port 1 and port 3 based on the differential of the average current of port 1 and the differential of the average current of port 3, so as to obtain the transfer relationship between the current and the phase shift angle; Among them, the structural parameters include at least one or more of the following: the switching tube of the converter, the voltage of each port, the current of each port, the transformer ratio of each port, the capacitance of each port, the sum of the inductance and leakage inductance connected in series to the first winding, the sum of the inductance and leakage inductance connected in series to the second winding, and the sum of the inductance and leakage inductance connected in series to the third winding.

11. The system according to claim 10, characterized in that The equivalent circuit model construction submodule is specifically used for: The transformer in the three-port DC-DC converter topology is set as an ideal transformer and the excitation inductance is ignored, and then a provisional three-port DC-DC converter equivalent circuit model is constructed according to the topology parameters of the three-port DC-DC converter; the provisional three-port DC-DC converter equivalent circuit model includes port 1, port 2, port 3 and an inductor network; The port 2 and the port 3 of the provisional three-port DC-DC converter equivalent circuit model are converted to the port 1, and the inductor network is transformed into a star-delta circuit to obtain the three-port DC-DC converter equivalent circuit model.

12. The system according to claim 10, characterized in that The expression of the transmission relationship between the current and the phase shift angle is as follows: Where, ΔI1 is the differential of the average current at port 1, ΔI3 is the differential of the average current at port 3, and G 11 , G 12 , G 21 , G 22 are all intermediate variables. is the differential of the phase shift angle between port 1 and port 2, is the differential of the phase shift angle between port 1 and port 3.

13. The system of claim 10, wherein: The feedforward decoupling network includes a feedforward decoupling network H 12 and the feedforward decoupling network H 21 ; The decoupling voltage loop module comprises: The first coupling variable determination submodule is used to apply the differential of the phase shift angle between the port 1 and the port 2 to the feedforward decoupling network H 21 , and obtain the corresponding coupling variables; The second coupling variable determination submodule is used to simultaneously apply the differential of the phase shift angle between the port 1 and the port 3 to the feedforward decoupling network H 12 , and obtain the corresponding coupling variables; A decoupled current and phase shift angle transfer relationship submodule, used for applying the two coupling variables to the transfer relationship between the current and the phase shift angle to obtain a decoupled current and phase shift angle transfer relationship; The decoupled voltage loop determination submodule is used to obtain the decoupled voltage loop according to the transmission relationship between the decoupled current and the phase shift angle.

14. The system of claim 13, wherein: The prediction control module comprises: An optimal shift phase ratio determination submodule is used to obtain an optimal shift phase ratio through a prediction model of a prediction controller based on the output voltage of the decoupled voltage loop; The predictive control submodule is used to apply the optimal phase shift angle to the transmission relationship between the decoupled current and the phase shift angle to complete the predictive control.

15. The system of claim 14, wherein: The system also includes: a prediction model building module, which is used to: Based on the relationship between the output capacitance of port 3 and the load resistance circuit, capacitance voltage and current in the main circuit topology mathematical model, the data relationship expression is obtained; According to the data relationship expression, forward difference is used to perform discretization to obtain the expression of the prediction model, thereby completing the construction of the prediction model.

16. The system of claim 15, wherein: The expression of the prediction model is as follows: Wherein, V3(k+1) is the square wave voltage of port 3 at time k+1, V1(k) is the square wave voltage of port 1 at time k, is the phase shift angle between port 1 and port 2 at time k, f s is the switching frequency of the converter, C3 is the capacitor of port 3, L3 is the sum of the inductance and leakage inductance connected in series to the third winding, T s is the switching period of the converter, V3(k) is the square wave voltage of port 3 at time k, and R0 is the load resistance.

17. An electronic device, characterized in that: include: at least one processor and memory; The memory and the processor are connected via a bus; The memory is used to store one or more programs; When the one or more programs are executed by the at least one processor, a predictive control method for a three-port DC-DC converter according to any one of claims 1 to 8 is implemented.

18. A readable storage medium, characterized in that: An execution program is stored thereon, and when the execution program is executed, a predictive control method for a three-port DC-DC converter as claimed in any one of claims 1 to 8 is implemented.

Images