VIENNA rectifier input inductance parameter determination method and system for automobile charging pile

Abstract

The invention provides an input inductance parameter determination method and system for a VIENNA rectifier of an automobile charging pile, and the method comprises the steps: determining a limit value of an AC side reactive current of the VIENNA rectifier of the automobile charging pile under a rated load condition; determining a mathematical model of the VIENNA rectifier under the dq coordinate system, and substituting a current control algorithm and a voltage feed-forward decoupling algorithm into the mathematical model under the dq coordinate system to obtain a control model under the dq coordinate system; simplifying the control model to obtain a d-axis instruction signal and a q-axis actual current; establishing a transfer function mathematical model of the d-axis instruction signal to the q-axis output signal by taking the d-axis instruction signal as an input quantity and the q-axis actual current as an output quantity; substituting the primary inductance parameter into a mathematical model of the d-axis signal to the q-axis signal to obtain a corresponding Bode diagram; and based on the Bode diagram, if the amplitude-frequency response of the parameter accords with the limit value of the VIENNA rectifier, determining that the primary inductance parameter is the input inductance parameter of the VIENNA rectifier. And the electric energy quality of the charging facility is improved.

Description

Technical Field

[0001] The present invention relates to the field of new energy vehicle electricity technology, and in particular to a method and system for determining input inductance parameters of a VIENNA rectifier used in a vehicle charging pile. Background Art

[0002] Electric vehicle charging stations are rapidly developing, with tens of millions now operational in China. VIENNA rectifiers theoretically enable harmonic-free AC current with a power factor of 1. However, in practice, many charging stations experience a phenomenon where the AC current waveform leads the voltage, and reactive power becomes capacitive. This leads to "reactive power backfeed," a problem explicitly prohibited by standards and regulations such as DL / T1773-2017, "Technical Guidelines for Voltage and Reactive Power in Power Systems," and "Regulations on Voltage Quality and Reactive Voltage Management in Power Systems."

[0003] The input inductance on the AC side of the VIENNA rectifier is a key parameter of the rectifier, which determines the current waveform and phase on the AC side of the rectifier. Previously, the parameter design of this inductor was basically based on several aspects such as "VIENNA rectifier voltage vector limitation", "rectifier diode rectification limitation" and "AC current ripple limitation". The core idea was to ensure that the current ripple was as small as possible under the premise of achieving the basic functions of the VIENNA rectifier, and the reactive power problem was not considered. In addition, the VIENNA rectifier usually adopts feedforward decoupling control and sets the reactive current target value to 0. When the controller performance is good enough, it is traditionally believed that the reactive current on the AC side of the rectifier is also equal to 0. This is also the reason why there has been no traditional method for designing inductor parameters from a reactive power perspective. Summary of the Invention

[0004] In response to the above technical problems, the present invention provides a method for determining the input inductance parameters of a VIENNA rectifier for a car charging pile, comprising:

[0005] Determine the capacitive reactive current limit of the Vienna rectifier of the vehicle charging station under rated load conditions;

[0006] Determine a mathematical model of the VIENNA rectifier in a dq coordinate system, substitute a current control algorithm and a voltage feedforward decoupling algorithm of the VIENNA rectifier into the mathematical model in the dq coordinate system, and obtain a control model of the VIENNA rectifier in the dq coordinate system;

[0007] The control model of the VIENNA rectifier in the dq coordinate system is simplified to obtain the d-axis command signal and the q-axis actual current; a mathematical model of the transfer function of the d-axis signal to the q-axis signal is established with the d-axis command signal as the input and the q-axis actual current as the output;

[0008] Preliminary inductance parameters are determined, and the preliminary inductance parameters are substituted into a mathematical model of the d-axis command signal and the q-axis output signal to obtain a Bode plot corresponding to the preliminary inductance parameters. Based on the Bode plot, if, under a given extremely low frequency, the amplitude-frequency response of the preliminary inductance parameters meets the limits of capacitive reactive current and active current of the VIENNA rectifier of the vehicle charging pile, then the preliminary inductance parameters are determined to be the input inductance parameters of the VIENNA rectifier of the vehicle charging pile.

[0009] Furthermore, the capacitive reactive current limit of the VIENNA rectifier of the vehicle charging pile is determined under rated load conditions. The limit η is determined by the following formula:

[0010]

[0011] Where, I q is the capacitive reactive current, I d is the capacitive active current, and η is the proportional coefficient limit.

[0012] Furthermore, a mathematical model of the VIENNA rectifier in the dq coordinate system is determined, and the current control algorithm and the voltage feedforward decoupling algorithm of the VIENNA rectifier are substituted into the mathematical model in the dq coordinate system to obtain the control model of the VIENNA rectifier in the dq coordinate system, which includes:

[0013] The mathematical model is:

[0014]

[0015] Where, the system voltage u in the ABC coordinate system is A 、u B 、u C and current i A 、i B 、i C In the dq coordinate system, it is expressed as u d 、u q and i d 、i q , S dq 、S dn and S qq 、S qn is the switching function in the dq coordinate system; U dc is the DC output voltage of the VIENNA rectifier, ω is the angular frequency of the power frequency fundamental wave;

[0016] If the current control algorithm adopts the proportional-integral control algorithm and introduces voltage feedforward decoupling, the following formula is obtained:

[0017]

[0018] Among them, K pi , K ii is the proportional control coefficient and integral control coefficient of the current loop, i d * and i q * are the current command values ​​of the d-axis and q-axis;

[0019] Based on the mathematical model, the above equation is transformed to obtain the control model of the VIENNA rectifier in the dq coordinate system, which is:

[0020]

[0021] Furthermore, the control model of the VIENNA rectifier in the dq coordinate system is simplified to obtain the d-axis command signal and the q-axis actual current, including:

[0022] By ignoring the command current signal, voltage signal and reactive current in the control model of the VIENNA rectifier in the dq coordinate system, the control model is simplified to obtain the d-axis command signal as i d * Input quantity, d-axis voltage signal U d is the interference input, with the actual current i of the d-axis and q-axis d and i q A single-input dual-output system with output quantity.

[0023] Furthermore, with the d-axis command signal as input and the q-axis actual current as output, a mathematical model of the transfer function of the d-axis signal to the q-axis signal is established, including:

[0024] Based on the single-input dual-output system, the d-axis command signal is i d * Input quantity, in terms of q-axis actual current i q As the output, a mathematical model of the transfer function of the d-axis signal to the q-axis signal is established, and the transfer function G is:

[0025]

[0026] Where s is the Laplace operator, ω is the fundamental angular frequency of the power frequency, L and r are the inductance and resistance of the input inductor of the VIENNA rectifier respectively, and K pi and K ii is the proportional control coefficient and integral control coefficient of the current loop, K PWM is the equivalent amplification factor of the rectifier.

[0027] Furthermore, it also includes:

[0028] Substituting the preselected inductance parameters L and r into the transfer function G(s), and plotting a Bode plot of the transfer function G(s); based on the Bode plot, if the amplitude-frequency response of the preselected inductance parameters meets the limits of the VIENNA rectifier under a given very low frequency, then determining that the preselected inductance parameters are the input inductance parameters of the VIENNA rectifier;

[0029] If the amplitude-frequency response of the initially selected inductance parameters does not meet the capacitive reactive current limit of the VIENNA rectifier of the car charging pile, reselect the inductance parameters L and r, redraw the Bode diagram, and determine whether it meets the capacitive reactive current limit of the VIENNA rectifier of the car charging pile based on the Bode diagram.

[0030] The present invention also provides a system for determining input inductance parameters of a VIENNA rectifier for a car charging pile, comprising:

[0031] A limit determination module is used to determine the capacitive reactive current limit of the VIENNA rectifier of the car charging pile under rated load conditions;

[0032] a control model determination module, configured to determine a mathematical model of the VIENNA rectifier in a dq coordinate system, substitute a current control algorithm and a voltage feedforward decoupling algorithm of the VIENNA rectifier into the mathematical model in the dq coordinate system, and obtain a control model of the VIENNA rectifier in the dq coordinate system;

[0033] a mathematical model building module for simplifying the control model of the VIENNA rectifier in the dq coordinate system to obtain the d-axis command signal and the q-axis actual current; and establishing a transfer function mathematical model of the d-axis command signal to the q-axis output signal using the d-axis command signal as input and the q-axis actual current as output;

[0034] An inductance parameter determination module is configured to determine a preliminary inductance parameter, substitute the preliminary inductance parameter into a mathematical model of the d-axis signal versus the q-axis signal, and obtain a Bode plot corresponding to the preliminary inductance parameter; and based on the Bode plot, if, under a given extremely low frequency, the amplitude-frequency response of the preliminary inductance parameter meets the capacitive reactive current and active current limits of the Vienna rectifier of the vehicle charging pile, then determine that the preliminary inductance parameter is the input inductance parameter of the Vienna rectifier of the vehicle charging pile.

[0035] Furthermore, in the limit value determination module, the limit value η is determined by the following formula:

[0036]

[0037] Where, I q is the capacitive reactive current, I dis the capacitive active current, and η is the proportional coefficient limit.

[0038] Furthermore, the mathematical model building module includes:

[0039] The single-input dual-output system determination submodule is used to simplify the control model of the VIENNA rectifier in the dq coordinate system by ignoring the command current signal, voltage signal and reactive current in the control model, and obtain the d-axis command signal as the i d * Input quantity, d-axis voltage signal U d is the interference input, with the actual current i of the d-axis and q-axis d and i q A single-input dual-output system with output quantity.

[0040] Furthermore, it also includes:

[0041] a first inductance parameter selection module, configured to substitute the preliminarily selected inductance parameters L and r into the transfer function G(s) and draw a Bode plot of the transfer function G(s); based on the Bode plot, if the amplitude-frequency response of the preliminarily selected inductance parameters meets the limits of the VIENNA rectifier under a given extremely low frequency, then determine that the preliminarily selected inductance parameters are the input inductance parameters of the VIENNA rectifier;

[0042] The second inductance parameter selection module is used to reselect the inductance parameter if the amplitude-frequency response of the initially selected inductance parameter does not meet the capacitive reactive current and active current limits of the VIENNA rectifier of the car charging pile, and determine whether it meets the capacitive reactive current and active current limits of the VIENNA rectifier of the car charging pile.

[0043] This invention provides a method and system for determining the input inductance parameters of a VIENNA rectifier for use in automobile charging piles. The system establishes a mathematical and control model for the VIENNA rectifier and, targeting the most common feedforward decoupling control used in charging piles, establishes a correlation between the q-axis component and the d-axis component under feedforward decoupling control. Finally, based on this correlation, the system analyzes the impact of the inductance parameters. Based on this established correlation, a reasonable inductance parameter value is designed, effectively alleviating the problem of reactive power backflow from the charging pile to the power grid and improving the power quality of the charging facility. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a flow chart of a method for determining input inductance parameters of a VIENNA rectifier for a car charging pile provided by an embodiment of the present invention;

[0045] Figure 2 1 is a control block diagram of a control model in a dq coordinate system of a VIENNA rectifier according to an embodiment of the present invention;

[0046] Figure 3 This is a block diagram of a mathematical model of a d-axis signal to a q-axis signal according to an embodiment of the present invention;

[0047] Figure 4 is a Bode diagram of a mathematical model of a d-axis signal versus a q-axis signal under different L values ​​used in the L value design involved in an embodiment of the present invention;

[0048] Figure 5 The present invention provides a schematic structural diagram of a system for determining input inductance parameters of a VIENNA rectifier for a vehicle charging pile. DETAILED DESCRIPTION

[0049] The following description sets forth numerous specific details to facilitate a thorough understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar generalizations without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific implementations disclosed below.

[0050] like Figure 1 As shown in FIG, a method and a flow chart for determining input inductance parameters of a VIENNA rectifier for a car charging pile provided by the present invention are provided, and the implementation steps include:

[0051] Step S101 : determining a capacitive reactive current limit of a VIENNA rectifier of a vehicle charging pile under rated load conditions.

[0052] For three-phase VIENNA rectifiers, it is clear that under rated load conditions, the capacitive reactive current is η times the limit of the active current, that is:

[0053]

[0054] Where, I q is the capacitive reactive current, I d is the capacitive active current, and η is the proportional coefficient limit.

[0055] Capacitive reactive current is the limit value of active current, which is the percentage value of capacitive reactive current to active current. η can be taken as no more than 5%, that is,

[0056]

[0057] Step S102 : determining a mathematical model of the VIENNA rectifier in the dq coordinate system, substituting the current control algorithm and the voltage feedforward decoupling algorithm of the VIENNA rectifier into the mathematical model in the dq coordinate system, and obtaining a control model of the VIENNA rectifier in the dq coordinate system.

[0058] According to the relevant knowledge of VIENNA rectifier, after 32 transformation and park transformation, the mathematical model of VIENNA rectifier in dq coordinate system is:

[0059]

[0060] Where, the system voltage u in the ABC coordinate system is A 、u B 、u C and current i A 、i B 、i C In the dq coordinate system, it is expressed as u d 、u q and i d 、i q , S dq 、S dn and S qq 、S qn is the switching function in the dq coordinate system; U dc is the DC output voltage of the VIENNA rectifier, and ω is the angular frequency of the power frequency fundamental wave; it can be seen that in the dq coordinate system, the d-axis (d-axis) and q-axis (q-axis) currents are mutually coupled.

[0061] If:

[0062]

[0063] Substituting it into the above formula, we have:

[0064]

[0065] According to the current control method actually used (including but not limited to proportional integral control (PI control), hysteresis control, periodic control, adaptive control, etc.), the mathematical model of the current control algorithm is substituted into the mathematical model of the VIENNA rectifier in the dq coordinate system. Assume that in this application example, the current control adopts the proportional integral (PI) control algorithm, and on this basis, the voltage feedforward decoupling is introduced, that is:

[0066]

[0067] Among them, K pi , K ii is the proportional control coefficient and integral control coefficient of the current loop, i d * and i q * are the current command values ​​of the d-axis and q-axis;

[0068] Based on the mathematical model, the above equation is transformed to obtain the control model of the VIENNA rectifier in the dq coordinate system, which is:

[0069]

[0070] It can be seen that there is no coupling between the DC component and the q-axis component of the current, and complete decoupling is achieved.

[0071] The established control model of VIENNA rectifier in dq coordinate system is as follows: Figure 2 shown.

[0072] Step S103, simplifying the control model of the VIENNA rectifier in the dq coordinate system to obtain the d-axis command signal and the q-axis actual current; using the d-axis command signal as the input and the q-axis actual current as the output, establishing a mathematical model of the transfer function of the d-axis signal to the q-axis signal.

[0073] In the established control model of the VIENNA rectifier in the dq coordinate system, the control goal of the VIENNA rectifier is usually to stabilize the current phase on the AC side and make it equal to the voltage phase, that is, for the q axis, there is a command current signal i q * =0; Under normal circumstances, the performance of the phase-locked loop is very good and can accurately lock the phase of the three-phase voltage signal. Therefore, for the q axis, there is a voltage signal U q = 0. In addition, the actual reactive current is generally not large, that is, the actual q-axis current i q Very small, feedback decoupling signal ωLi q The output of the signal on the d-axis is also very small. d It has basically no effect and can be ignored.

[0074] After ignoring the above three signals, Figure 2 The control block diagram can be simplified to Figure 3 This is a d-axis command signal. d * Input quantity, d-axis voltage signal U d is the interference input, with the actual current i of the d-axis and q-axis d and i q A single-input dual-output system with output quantity.

[0075] Normally, the active power control of VIENNA rectifier is very accurate, i.e. d =i d * Even if there is a difference between the two, it mainly exists in the high frequency band, the low frequency band and the medium frequency band are not the same. d * and i dThe difference in amplitude and phase is very small. Therefore, in this application example, the d-axis output signal is taken as i d As input, the actual current i of q axis q Establish a transfer function model for the output quantity, such as Figure 3 As shown in the dotted box in the figure. According to its control block diagram, its transfer function G is:

[0076]

[0077] Where s is the Laplace operator, ω is the fundamental angular frequency of the power frequency, L and r are the inductance and resistance of the input inductor of the VIENNA rectifier respectively, and K pi and K ii is the proportional control coefficient and integral control coefficient of the current loop, K PWM is the equivalent amplification factor of the rectifier.

[0078] Step S104: Determine preliminary inductance parameters, substitute the preliminary inductance parameters into the mathematical model of the d-axis command signal and the q-axis output signal, and obtain a Bode plot corresponding to the preliminary inductance parameters. Based on the Bode plot, if, under a given extremely low frequency, the amplitude-frequency response of the preliminary inductance parameters meets the capacitive reactive current and active current limits of the VIENNA rectifier of the vehicle charging pile, then determine that the preliminary inductance parameters are the input inductance parameters of the VIENNA rectifier of the vehicle charging pile.

[0079] Next, we will design the inductor L parameters. We can preliminarily select the value of the inductor L, substitute it into the mathematical model of the transfer function of the d-axis signal to the q-axis signal, and draw its Bode diagram.

[0080] The amplitude-frequency response of the Bode plot is then examined at a given very low frequency (less than or equal to 0.2 Hz) to see if it meets the capacitive reactive and active current limits of the Vienna rectifier used in the vehicle charging station.

[0081] If it does not meet the requirements, select a new inductor L value and substitute it into the transfer function mathematical model of the d-axis signal to the q-axis signal again to draw a Bode plot. Determine whether its amplitude-frequency response at a given very low frequency (less than or equal to 0.2Hz) meets the capacitive reactive current and active current limits of the VIENNA rectifier of the car charging pile; if it does, the design process ends. If it does not meet the requirements, continue to select the inductor L value repeatedly. The specific steps are as follows:

[0082] 1) The initial inductance value is 4mH. In this application example, the actual parameters of the VIENNA rectifier PI controller are 0.4 and 2 respectively. The gain factor K of the VIENNA rectifier is PWM is 100;

[0083] 2) Substitute the above parameter values ​​and draw the Bode diagram of the above formula, as shown in Figure 4 As shown;

[0084] 3) The active and reactive current components in a 50H system should be DC quantities in the dq coordinate system. However, the actual grid frequency cannot be stable at 50Hz all the time, but fluctuates around 50Hz. The national standard GB / T15945-2008 "Frequency Deviation of Power Quality Power System" allows a grid frequency deviation of ±0.2Hz. Therefore, the command current and actual current in the dq coordinate system are both extremely low-frequency AC quantities. This application example assumes that the actual grid frequency deviation is 0.05Hz (corresponding to a frequency of 50.05Hz or 49.95Hz in the three-phase static ABC coordinate system). Figure 4 It can be seen that the amplitude-frequency response at 0.05Hz is -14.1dB, that is, i q The amplitude is i d 19.72%, which does not meet the expected target.

[0085] 4) Reselect L = 2mH, repeat steps 2) to 3), and draw the Bode plot of the above formula as shown below: Figure 4 As shown, the amplitude-frequency response at 0.05Hz is -20.1dB, i q The amplitude is i d The 9.89% is still not in line with the expected target.

[0086] 5) Reselect L = 1mH, repeat steps 2) to 3), and draw the Bode plot of the above formula as shown below: Figure 4 As shown, the amplitude-frequency response at 0.05Hz is -26.1dB, i q The amplitude is i d The growth rate was 4.95%, in line with the expected target.

[0087] 6) There are no technical difficulties in designing a 4mH inductor value. Therefore, the final design value of the Vienna rectifier inductor is 1mH.

[0088] It should be noted that Figure 4 The Bode plots of the three initially selected inductance values ​​in this application example are plotted on the same graph for easy comparison and observation. In actual application of the method of the present invention, three independent Bode plots can also be plotted.

[0089] It's also important to note that, since actual inductors are wound with copper or aluminum coils, they inevitably have a resistance component, r. Typically, this resistance component, r, cannot be deliberately selected; it maintains a relatively fixed relationship with the inductance value, L, and is determined by the inductor's quality factor. Therefore, in this application example, the value of the resistance component, r, was not discussed during the initial selection of inductor parameters.

[0090] Based on the same inventive concept, the present invention also provides a VIENNA rectifier input inductance parameter determination system 500 for a car charging pile, such as Figure 5 Shown, including:

[0091] The limit determination module 5100 is used to determine the capacitive reactive current limit of the Vienna rectifier of the vehicle charging pile under rated load conditions;

[0092] a control model determination module 5200 for determining a mathematical model of the VIENNA rectifier in a dq coordinate system, substituting a current control algorithm and a voltage feedforward decoupling algorithm of the VIENNA rectifier into the mathematical model in the dq coordinate system, and obtaining a control model of the VIENNA rectifier in the dq coordinate system;

[0093] The mathematical model building module 530 is used to simplify the control model of the VIENNA rectifier in the dq coordinate system to obtain the d-axis command signal and the q-axis actual current; using the d-axis command signal as the input and the q-axis actual current as the output, establish a transfer function mathematical model of the d-axis command signal to the q-axis output signal;

[0094] An inductance parameter determination module 540 is configured to determine a preliminary inductance parameter, substitute the preliminary inductance parameter into the mathematical model of the d-axis signal versus the q-axis signal, and obtain a Bode plot corresponding to the preliminary inductance parameter. Based on the Bode plot, if, at a given extremely low frequency, the amplitude-frequency response of the preliminary inductance parameter meets the capacitive reactive current and active current limits of the Vienna rectifier of the vehicle charging station, then the preliminary inductance parameter is determined to be the input inductance parameter of the Vienna rectifier of the vehicle charging station.

[0095] Furthermore, in the limit value determination module, the limit value η is determined by the following formula:

[0096]

[0097] Where, I q is the capacitive reactive current, I d is the capacitive active current, and η is the proportional coefficient limit.

[0098] Furthermore, the mathematical model building module includes:

[0099] The single-input dual-output system determination submodule is used to simplify the control model of the VIENNA rectifier in the dq coordinate system by ignoring the command current signal, voltage signal and reactive current in the control model, and obtain the d-axis command signal as the i d * Input quantity, d-axis voltage signal U dis the interference input, with the actual current i of the d-axis and q-axis d and i q A single-input dual-output system with output quantity.

[0100] Furthermore, it also includes:

[0101] a first inductance parameter selection module, configured to substitute the preliminarily selected inductance parameters L and r into the transfer function G(s) and draw a Bode plot of the transfer function G(s); based on the Bode plot, if the amplitude-frequency response of the preliminarily selected inductance parameters meets the limits of the VIENNA rectifier under a given extremely low frequency, then determine that the preliminarily selected inductance parameters are the input inductance parameters of the VIENNA rectifier;

[0102] The second inductance parameter selection module is used to reselect the inductance parameter if the amplitude-frequency response of the initially selected inductance parameter does not meet the capacitive reactive current and active current limits of the VIENNA rectifier of the car charging pile, and determine whether it meets the capacitive reactive current limit of the VIENNA rectifier of the car charging pile.

[0103] This invention provides a method and system for determining the input inductance parameters of a VIENNA rectifier for use in automobile charging piles. The system establishes a mathematical and control model for the VIENNA rectifier and, targeting the most common feedforward decoupling control used in charging piles, establishes a correlation between the q-axis component and the d-axis component under feedforward decoupling control. Finally, based on this correlation, the system analyzes the impact of the inductance parameters. Based on this established correlation, a reasonable inductance parameter value is designed, effectively alleviating the problem of reactive power backflow from the charging pile to the power grid and improving the power quality of the charging facility.

[0104] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0105] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, 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 produce 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 flowcharts and / or block diagrams. 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.

[0106] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0107] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modifications or equivalents that do not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for determining the input inductance parameters of a VIENNA rectifier for a car charging pile, characterized in that: include: Determine the capacitive reactive current limit of the Vienna rectifier of the vehicle charging station under rated load conditions; Determine a mathematical model of the VIENNA rectifier in a dq coordinate system, substitute a current control algorithm and a voltage feedforward decoupling algorithm of the VIENNA rectifier into the mathematical model in the dq coordinate system, and obtain a control model of the VIENNA rectifier in the dq coordinate system; The control model of the VIENNA rectifier in the dq coordinate system is simplified to obtain the d-axis command signal and the q-axis actual current; a mathematical model of the transfer function of the d-axis signal to the q-axis signal is established with the d-axis command signal as the input and the q-axis actual current as the output; Preliminary inductance parameters are determined, and the preliminary inductance parameters are substituted into a mathematical model of the d-axis command signal and the q-axis output signal to obtain a Bode plot corresponding to the preliminary inductance parameters. Based on the Bode plot, if, under a given extremely low frequency, the amplitude-frequency response of the preliminary inductance parameters meets the limits of capacitive reactive current and active current of the VIENNA rectifier of the vehicle charging pile, then the preliminary inductance parameters are determined to be the input inductance parameters of the VIENNA rectifier of the vehicle charging pile.

2. The method according to claim 1, characterized in that Determine the capacitive reactive current limit of the Vienna rectifier of the vehicle charging pile under rated load conditions. The limit η is determined by the following formula: Where, I q is the capacitive reactive current, I d is the capacitive active current, and η is the proportional coefficient limit.

3. The method according to claim 1, characterized in that Determine the mathematical model of the VIENNA rectifier in the dq coordinate system, substitute the current control algorithm and the voltage feedforward decoupling algorithm of the VIENNA rectifier into the mathematical model in the dq coordinate system, and obtain the control model of the VIENNA rectifier in the dq coordinate system, which includes: The mathematical model is: Where, the system voltage u in the ABC coordinate system is A 、u B 、u C and current i A 、i B 、i C In the dq coordinate system, it is expressed as u d 、u q and i d 、i q , S dq 、S dn and S qq 、S qn is the switching function in the dq coordinate system; U dc is the DC output voltage of the VIENNA rectifier, ω is the angular frequency of the power frequency fundamental wave; If the current control algorithm adopts the proportional-integral control algorithm and introduces voltage feedforward decoupling, the following formula is obtained: Among them, K pi , K ii is the proportional control coefficient and integral control coefficient of the current loop, i d * and i q * are the current command values ​​of the d-axis and q-axis; Based on the mathematical model, the above equation is transformed to obtain the control model of the VIENNA rectifier in the dq coordinate system, which is:

4. The method according to claim 1, wherein The control model of the VIENNA rectifier in the dq coordinate system is simplified to obtain the d-axis command signal and the q-axis actual current, including: By ignoring the command current signal, voltage signal and reactive current in the control model of the VIENNA rectifier in the dq coordinate system, the control model is simplified to obtain the d-axis command signal as i d * Input quantity, d-axis voltage signal U d is the interference input, with the actual current i of the d-axis and q-axis d and i q A single-input dual-output system with output quantity.

5. The method according to claim 1 or 4, characterized in that With the d-axis command signal as input and the q-axis actual current as output, a mathematical model of the transfer function of the d-axis signal to the q-axis signal is established, including: Based on the single-input dual-output system, the d-axis command signal is i d * Input quantity, in terms of q-axis actual current i q As the output, a mathematical model of the transfer function of the d-axis signal to the q-axis signal is established, and the transfer function G(s) is: Where s is the Laplace operator, ω is the fundamental angular frequency of the power frequency, L and r are the inductance and resistance of the input inductor of the VIENNA rectifier respectively, and K pi and K ii is the proportional control coefficient and integral control coefficient of the current loop, K PWM is the equivalent amplification factor of the rectifier.

6. The method according to claim 1, characterized in that Also includes: Substituting the preselected inductance parameters L and r into the transfer function G(s), and plotting a Bode plot of the transfer function G(s); based on the Bode plot, if the amplitude-frequency response of the preselected inductance parameters meets the limits of the VIENNA rectifier under a given very low frequency, then determining that the preselected inductance parameters are the input inductance parameters of the VIENNA rectifier; If the amplitude-frequency response of the initially selected inductance parameters does not meet the capacitive reactive current limit of the VIENNA rectifier of the car charging pile, reselect the inductance parameters L and r, redraw the Bode diagram, and determine whether it meets the capacitive reactive current limit of the VIENNA rectifier of the car charging pile based on the Bode diagram.

7. A system for determining input inductance parameters of a VIENNA rectifier for a car charging pile, characterized in that: include: A limit determination module is used to determine the capacitive reactive current limit of the VIENNA rectifier of the car charging pile under rated load conditions; a control model determination module, configured to determine a mathematical model of the VIENNA rectifier in a dq coordinate system, substitute a current control algorithm and a voltage feedforward decoupling algorithm of the VIENNA rectifier into the mathematical model in the dq coordinate system, and obtain a control model of the VIENNA rectifier in the dq coordinate system; a mathematical model building module for simplifying the control model of the VIENNA rectifier in the dq coordinate system to obtain the d-axis command signal and the q-axis actual current; and establishing a transfer function mathematical model of the d-axis command signal to the q-axis output signal using the d-axis command signal as input and the q-axis actual current as output; An inductance parameter determination module is configured to determine a preliminary inductance parameter, substitute the preliminary inductance parameter into a mathematical model of the d-axis signal versus the q-axis signal, and obtain a Bode plot corresponding to the preliminary inductance parameter; and based on the Bode plot, if, under a given extremely low frequency, the amplitude-frequency response of the preliminary inductance parameter meets the capacitive reactive current and active current limits of the Vienna rectifier of the vehicle charging pile, then determine that the preliminary inductance parameter is the input inductance parameter of the Vienna rectifier of the vehicle charging pile.

8. The system according to claim 7, characterized in that In the limit determination module, the limit η is determined by the following formula: Where, I q is the capacitive reactive current, I d is the capacitive active current, and η is the proportional coefficient limit.

9. The system according to claim 7, wherein: Mathematical model building module, including: The single-input dual-output system determination submodule is used to simplify the control model of the VIENNA rectifier in the dq coordinate system by ignoring the command current signal, voltage signal and reactive current in the control model, and obtain the d-axis command signal as the i d * Input quantity, d-axis voltage signal U d is the interference input, with the actual current i of the d-axis and q-axis d and i q A single-input dual-output system with output quantity.

10. The system according to claim 7, wherein: Also includes: a first inductance parameter selection module, configured to substitute the preliminarily selected inductance parameters L and r into the transfer function G(s) and draw a Bode plot of the transfer function G(s); based on the Bode plot, if the amplitude-frequency response of the preliminarily selected inductance parameters meets the limits of the VIENNA rectifier under a given extremely low frequency, then determine that the preliminarily selected inductance parameters are the input inductance parameters of the VIENNA rectifier; The second inductance parameter selection module is used to reselect the inductance parameter if the amplitude-frequency response of the initially selected inductance parameter does not meet the capacitive reactive current and active current limits of the VIENNA rectifier of the car charging pile, and determine whether it meets the capacitive reactive current limit of the VIENNA rectifier of the car charging pile.

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