Automatic control method and system for bidirectional direct current charging pile

Abstract

The application provides an automatic control method and system of a bidirectional direct-current charging pile, wherein the automatic control method comprises the following steps: acquiring a first voltage reference value, a first current reference value, a first voltage actual value, a first current actual value and a virtual impedance value input / output by a direct-current gun head of the charging pile; generating a first PWM control signal according to the first voltage reference value, the first current reference value, the first voltage actual value, the first current actual value and the virtual impedance value; after receiving a charging instruction, controlling a DC / DC module to output a first demand voltage to a charging battery according to the first PWM control signal, or after receiving a discharging instruction, controlling the DC / DC module to output a second demand voltage to a direct-current bus according to the first PWM control signal. According to the automatic control method of the bidirectional direct-current charging pile, automatic switching of the charging and discharging modes can be realized, the state switching time is short, and the frequency and voltage adjustment requirements of the power system can be met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bidirectional direct current charging pile control, in particular to an automatic control method of bidirectional direct current charging pile and an automatic control system of bidirectional direct current charging pile. BACKGROUND

[0002] With the large-scale access of new energy vehicle charging piles to the power grid, the capacity proportion of the charging piles in the power system gradually rises. Reasonable use of the energy storage function of the power battery of the electric vehicle can help the vehicle owner obtain the peak-valley price income of the power grid company on the one hand, and can provide technical support for the frequency and voltage regulation demand of the power system on the other hand.

[0003] In the related art, a bidirectional direct current charging pile is used to realize the functions of forward charging and reverse discharging. However, the switching between the charging and discharging modes needs to be completed in the shutdown state of the system, and the state switching time generated thereby is far more than the 100ms time limit in the energy storage converter technical specification (GB / T 34120-2017), which cannot meet the frequency and voltage regulation demand of the power system. SUMMARY

[0004] To solve the above technical problems, the present application provides an automatic control method of bidirectional direct current charging pile, which can realize automatic switching between the charging and discharging modes, and has short state switching time, thereby meeting the frequency and voltage regulation demand of the power system.

[0005] The technical scheme adopted by the present application is as follows:

[0006] An automatic control method of bidirectional direct current charging pile, the bidirectional direct current charging pile comprising a DC / DC module, a direct current bus and a DC / AC module, wherein the first end of the DC / DC module is connected with a charging battery of a vehicle to be charged, the second end of the DC / DC module is connected with the first end of the direct current bus, the second end of the direct current bus is connected with the first end of the DC / AC module, and the second end of the DC / AC module is connected with an alternating current power grid, the automatic control method comprising: acquiring a first voltage reference value, a first current reference value, a first voltage actual value, a first current actual value and a virtual impedance value input / output by a direct current gun head of the charging pile; generating a first PWM (Pulse Width Modulation) control signal according to the first voltage reference value, the first current reference value, the first voltage actual value, the first current actual value and the virtual impedance value; after receiving a charging instruction, controlling the DC / DC module to output a first demand voltage to the charging battery according to the first PWM control signal, or after receiving a discharging instruction, controlling the DC / DC module to output a second demand voltage to the direct current bus according to the first PWM control signal.

[0007] In one embodiment of the present application, the automatic control method further comprises: obtaining a bus voltage reference value, a bus voltage actual value and a zero sequence current modulation component; generating a second PWM control signal according to the bus voltage reference value, the bus voltage actual value and the zero sequence current modulation component; after receiving a charging instruction, controlling the DC / AC module to output a third required voltage to the DC bus according to the second PWM control signal, or, after receiving a discharging instruction, controlling the DC / AC module to output a fourth required voltage to the AC power grid according to the second PWM control signal.

[0008] In one embodiment of the present application, generating the first PWM control signal according to the first voltage reference value, the first current reference value, the first voltage actual value, the first current actual value and the virtual impedance value comprises: obtaining a first voltage deviation value according to the first voltage reference value and the first voltage actual value; obtaining a second current actual value according to the first current actual value and the virtual impedance value; obtaining a first current deviation value according to the second current actual value and the first current reference value; respectively performing PI regulation on the first voltage deviation value and the first current deviation value to obtain a first regulated voltage value and a first regulated current value; and generating the first PWM control signal according to the first regulated voltage value and the first regulated current value.

[0009] In one embodiment of the present application, obtaining the virtual impedance value comprises: obtaining a second voltage deviation value according to the bus voltage reference value and the bus voltage actual value; performing impedance transformation on the second voltage deviation value by using a first virtual impedance coefficient to generate a transient virtual impedance; obtaining a power reference value and a power actual value of the input / output of the DC / DC module; obtaining a power deviation value according to the power reference value and the power actual value; performing impedance transformation on the power deviation value by using a second virtual impedance coefficient to generate a steady-state virtual impedance; and performing superposition operation on the transient virtual impedance and the steady-state virtual impedance to obtain the virtual impedance value.

[0010] In one embodiment of the present application, obtaining the zero sequence current modulation component comprises: obtaining three-phase current actual values and three-phase current reference values of three-phase grid-connected currents during discharging of the bidirectional DC charging pile; superimposing the three-phase current actual values to obtain a zero sequence current feedback value, and superimposing the three-phase current reference values to obtain a zero sequence current reference value; obtaining a zero sequence current deviation value according to the zero sequence current feedback value and the zero sequence current reference value; and adjusting the zero sequence current deviation value by using a proportional-resonant controller to obtain the zero sequence current modulation component.

[0011] The application discloses an automatic control system of a bidirectional direct-current charging pile, and the bidirectional direct-current charging pile comprises a DC / DC module, a direct-current bus and a DC / AC module, wherein the first end of the DC / DC module is connected with a charging battery of a vehicle to be charged, the second end of the DC / DC module is connected with the first end of the direct-current bus, the second end of the direct-current bus is connected with the first end of the DC / AC module, the second end of the DC / AC module is connected with an alternating-current power grid, the automatic control system comprises a first acquisition unit, the first acquisition unit is used for acquiring a first voltage reference value, a first current reference value, a first voltage actual value, a first current actual value and a virtual impedance value input / output by a direct-current gun head of the charging pile, a generation unit, the generation unit is used for generating a first PWM control signal according to the first voltage reference value, the first current reference value, the first voltage actual value, the first current actual value and the virtual impedance value, and a first control unit, the first control unit is used for controlling the DC / DC module to output a first demand voltage to the charging battery according to the first PWM control signal after receiving a charging instruction, or controlling the DC / DC module to output a second demand voltage to the direct-current bus according to the first PWM control signal after receiving a discharging instruction.

[0012] In one embodiment of the application, the automatic control system further comprises a second acquisition unit, the second acquisition unit acquires a bus voltage reference value, a bus voltage actual value and a zero-sequence current modulation component, generates a second PWM control signal according to the bus voltage reference value, the bus voltage actual value and the zero-sequence current modulation component, and a second control unit, the second control unit is used for controlling the DC / AC module to output a third demand voltage to the direct-current bus according to the second PWM control signal after receiving a charging instruction, or controlling the DC / AC module to output a fourth demand voltage to the alternating-current power grid according to the second PWM control signal after receiving a discharging instruction.

[0013] A computer device comprises a memory, a processor and a computer program stored on the memory and capable of running on the processor, and the processor implements the automatic control method of the bidirectional direct-current charging pile when executing the computer program.

[0014] A non-transitory computer readable storage medium, which stores a computer program, and the program is executed by a processor to implement the automatic control method of the bidirectional direct-current charging pile.

[0015] The application has the following beneficial effects:

[0016] The application can realize automatic switching of charging and discharging modes, and the state switching time is short, so that the frequency and voltage regulating requirements of the power system can be met. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a flow chart of the automatic control method of the bidirectional DC charging pile according to an embodiment of the present application.

[0018] Figure 2 is a logic diagram of the method for obtaining a virtual impedance value according to an embodiment of the present application.

[0019] Figure 3 is a logic diagram of the method for generating a first PWM control signal according to an embodiment of the present application.

[0020] Figure 4 is a logic diagram of the method for generating a second PWM control signal according to an embodiment of the present application.

[0021] Figure 5 is a logic diagram of the method for obtaining a zero sequence current modulation component according to an embodiment of the present application.

[0022] Figure 6 is a block diagram of the automatic control system of the bidirectional DC charging pile according to an embodiment of the present application. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0024] Figure 1 is a flow chart of the automatic control method of the bidirectional DC charging pile according to an embodiment of the present application.

[0025] It should be noted that the bidirectional DC charging pile includes a DC / DC module, a DC bus and a DC / AC module, wherein the first end of the DC / DC module is connected to a charging battery of a vehicle to be charged, the second end of the DC / DC module is connected to the first end of the DC bus, the second end of the DC bus is connected to the first end of the DC / AC module, and the second end of the DC / AC module is connected to an AC power grid.

[0026] Specifically, in the charging mode, the DC / AC module rectifies AC power of the AC power grid to the Bus (DC bus) and outputs a required voltage of an EV (Electric Vehicle, electric vehicle) Battery (charging battery) through an isolated DC / DC module. In the discharging mode, the charging battery charges the DC bus through the DC / DC module, and then the DC / AC module inverts to the AC power grid.

[0027] As shown in Figure 1 The automatic control method of the bidirectional DC charging pile can include the following steps:

[0028] S1, obtaining a first voltage reference value, a first current reference value, a first voltage actual value, a first current actual value and a virtual impedance value input / output by a DC gun head of the charging pile.

[0029] Specifically, the first voltage reference value VoutRef and the first current reference value IoutRef input / output by the DC gun head of the charging pile can be obtained first, wherein the first voltage reference value VoutRef and the first current reference value IoutRef are both issued by the vehicle-side BMS (Battery Management System), the first current reference value IoutRef can be appropriately processed to be smaller according to the parameters (de-rating power limit) of the charging pile itself, and the first voltage actual value Vout and the first current actual value Iout input / output by the DC gun head of the charging pile are obtained, and the virtual impedance value Zvirtual is obtained.

[0030] In an embodiment of the present application, obtaining the virtual impedance value includes: obtaining a second voltage deviation value according to the bus voltage reference value and the bus voltage actual value; performing impedance transformation on the second voltage deviation value by using a first virtual impedance coefficient to generate a transient virtual impedance; obtaining a power reference value and a power actual value input / output by the DC / DC module; obtaining a power deviation value according to the power reference value and the power actual value; performing impedance transformation on the power deviation value by using a second virtual impedance coefficient to generate a steady-state virtual impedance; and performing superposition operation on the transient virtual impedance and the steady-state virtual impedance to obtain the virtual impedance value.

[0031] Specifically, as shown in Figure 2As shown, the virtual impedance value Zvirtual can include two parts, one part is the instantaneous virtual impedance generated by impedance transformation (using the first virtual impedance coefficient Z1) of the second voltage deviation value of the bus voltage reference value BusRef and the bus voltage actual value BusVolt, and the other part is the steady-state virtual impedance generated by impedance transformation (using the second virtual impedance coefficient Z2) of the power deviation value of the power reference value PowerRef and the power actual value Power of the DC / DC module input / output, and then the two parts are superimposed to obtain the virtual impedance value, and the virtual impedance value is added to the feedback loop of the DC / DC module current control loop. Thus, the instantaneous impact of the bus voltage caused by the sudden change of the grid voltage or the rapid scheduling of the grid-connected power in the discharge mode is suppressed or eliminated by the instantaneous virtual impedance, wherein the size of the first virtual impedance coefficient Z1 is related to the charging pile DC bus capacitance value and the bus voltage deviation size, and the steady-state error of the DC bus voltage caused by the deviation between the AC / DC module and the DC / DC module output power instruction due to the grid-connected power limit (including grid scheduling, frequency active response, grid high voltage drop, and other grid-connected standard requirements) of the charging pile in the discharge mode is eliminated by the steady-state virtual impedance, wherein the size of the second virtual impedance coefficient Z2 is related to the rated power of the charging pile and the power deviation size.

[0032] S2, generating a first PWM control signal according to the first voltage reference value, the first current reference value, the first voltage actual value, the first current actual value and the virtual impedance value.

[0033] In an embodiment of the present application, the first PWM control signal is generated according to the first voltage reference value, the first current reference value, the first voltage actual value, the first current actual value and the virtual impedance value, comprising: obtaining a first voltage deviation value according to the first voltage reference value and the first voltage actual value; obtaining a second current actual value according to the first current actual value and the virtual impedance value; obtaining a first current deviation value according to the second current actual value and the first current reference value; respectively PI regulating the first voltage deviation value and the first current deviation value to obtain a first regulated voltage value and a first regulated current value; and generating the first PWM control signal according to the first regulated voltage value and the first regulated current value.

[0034] Specifically, as Figure 3As shown, first, a first voltage deviation value (difference operation) of the first voltage reference value VoutRef and the first voltage actual value Vout can be acquired, and a superposition operation of the first current actual value Iout and the virtual impedance value Zvirtual is performed to acquire a second current actual value, and a first current deviation value (difference operation) of the second current actual value and the first current reference value IoutRef is acquired. Then, PI regulation is performed on the first voltage deviation value and the first current deviation value respectively to acquire a first regulated voltage value and a first regulated current value. Finally, the voltage and current competition module is used to take the optimal value according to the first regulated voltage value and the first regulated current value, and the first PWM control signal is output through the PWM generator. Thus, the virtual impedance value Zvirtual is superimposed in the feedback loop of the DC / DC current control loop, which can reduce or even eliminate the DC bus fluctuation caused by the power change of the DC / AC module.

[0035] S3, after receiving the charging instruction, the DC / DC module outputs the first demand voltage to the charging battery according to the first PWM control signal, or, after receiving the discharging instruction, the DC / DC module outputs the second demand voltage to the DC bus according to the first PWM control signal.

[0036] Specifically, after the first PWM control signal is acquired in the above manner, the first PWM control signal can be input to the control end of each IGBT in the DC / DC module, so as to control the DC / DC module to output the first demand voltage to the charging battery after receiving the charging instruction, or to control the DC / DC module to output the second demand voltage to the DC bus according to the first PWM control signal after receiving the discharging instruction. In an embodiment of the present application, the automatic control method of the bidirectional direct current charging pile further comprises: acquiring a bus voltage reference value, a bus voltage actual value and a zero sequence current modulation component; generating a second PWM control signal according to the bus voltage reference value, the bus voltage actual value and the zero sequence current modulation component; after receiving the charging instruction, the DC / AC module outputs the third demand voltage to the DC bus according to the second PWM control signal, or, after receiving the discharging instruction, the DC / AC module outputs the fourth demand voltage to the alternating current power grid according to the second PWM control signal.

[0037] Specifically, as shown in FIG. 4, the DC / DC module 1 comprises a first current loop 11, a first voltage loop 12, a voltage and current competition module 13 and a PWM generator 14. The first current loop 11 comprises a first current reference value IoutRef, a first current actual value Iout, a virtual impedance value Zvirtual and a first current deviation value IoutDev. The first voltage loop 12 comprises a first voltage reference value VoutRef, a first voltage actual value Vout and a first voltage deviation value VoutDev. The voltage and current competition module 13 is connected to the first voltage loop 12 and the first current loop 11, and the PWM generator 14 is connected to the voltage and current competition module 13. Figure 4As shown, after obtaining the third voltage deviation value of the bus voltage reference value BusRef and the bus voltage actual value BusVolt, the outer ring outputs the D-axis current reference value IdRef through PI regulation, the inner ring DQ current control loop outputs the grid voltage feedforward Vd / Vq and the current feedforward Id / Iq, and after corresponding processing (including difference operation, PI regulation and superposition operation) of the D-axis current reference value IdRef, the Q-axis current reference value IqRef, the grid voltage feedforward Vd / Vq and the current feedforward Id / Iq, the three-phase voltage modulation wave Vabc is generated through inverse Park transformation (dq / abc), then, after superposition operation of the three-phase voltage modulation wave Vabc and the zero sequence current modulation component Vzero, the second PWM control signal is output through the PWM generator, and the second PWM control signal is input into the control end of each IGBT in the DC / AC module, so as to control the DC / AC module to output the third demand voltage to the DC bus after receiving the charging instruction, or to control the DC / AC module to output the fourth demand voltage to the AC grid after receiving the discharging instruction.

[0038] It should be noted that the bidirectional charging pile usually requires to have zero power grid feeding function during grid-connected discharging, especially in the V2H (vehicle to home) scenario, that is, the power of the reverse discharging of the charging pile cannot exceed the household load. For the three-phase grid-connected charging pile, due to the uncertainty of the wiring and power size of the household load, it is necessary to have three-phase current unbalanced output capability to meet the standard requirement of zero power grid feeding. Therefore, the present application introduces a zero sequence current control loop to support three-phase current unbalanced output capability of the bidirectional DC charging pile in the reverse grid-connected discharging mode, and at the same time has the effect of harmonic optimization.

[0039] In an embodiment of the present application, obtaining the zero sequence current modulation component comprises: obtaining three-phase current actual values and three-phase current reference values of three-phase grid-connected currents during discharging of the bidirectional DC charging pile; superimposing the three-phase current actual values to obtain a zero sequence current feedback value, and superimposing the three-phase current reference values to obtain a zero sequence current reference value; obtaining a zero sequence current deviation value according to the zero sequence current feedback value and the zero sequence current reference value; and adjusting the zero sequence current deviation value by using a proportional-resonant controller to obtain the zero sequence current modulation component.

[0040] Specifically, as shown in FIG. 4, the zero sequence current control loop comprises a zero sequence current feedback loop and a zero sequence current reference loop. Figure 5As shown, first, the three-phase current actual values (Ia, Ib and Ic) are superimposed to obtain a zero-sequence current feedback value Izero (after superimposing the three-phase current actual values, a third virtual impedance coefficient, for example, 1 / 3, can also be used for impedance transformation to obtain the zero-sequence current feedback value), and the three-phase current reference values (IaRef, IbRef and IcRef) are superimposed to obtain a zero-sequence current reference value IzeroRef (after superimposing the three-phase current reference values, a third virtual impedance coefficient, for example, 1 / 3, can also be used for impedance transformation to obtain the zero-sequence current reference value). Second, the zero-sequence current feedback value Izero and the zero-sequence current reference value IzeroRef are subjected to difference operation to obtain a zero-sequence current deviation value Izero_Err. Then, the zero-sequence current deviation value Izero_Err is adjusted by using a proportional-resonant controller PR1 / PR3 / PR5, and the adjustment result is subjected to superimposition operation to obtain a zero-sequence current modulation component Vzero. Among them, PR1 is a zero-sequence current fundamental controller for tracking the zero-sequence current fundamental component, and PR3 / PR5 are zero-sequence current three-fold / five-fold controllers for suppressing the zero-sequence current harmonic component to indirectly optimize the harmonic quality when the three-phase grid-connected current imbalance output.

[0041] In summary, according to the automatic control method of the bidirectional DC charging pile, the first voltage reference value, the first current reference value, the first voltage actual value, the first current actual value and the virtual impedance value of the DC gun head input / output of the charging pile are obtained, the first PWM control signal is generated according to the first voltage reference value, the first current reference value, the first voltage actual value, the first current actual value and the virtual impedance value, and after receiving the charging instruction, the DC / DC module outputs the first demand voltage to the charging battery according to the first PWM control signal, or after receiving the discharging instruction, the DC / DC module outputs the second demand voltage to the DC bus according to the first PWM control signal. Therefore, the automatic switching of the charging and discharging modes can be realized, the state switching time is short, and the frequency and voltage regulation requirements of the power system can be met.

[0042] Corresponding to the automatic control method of the bidirectional DC charging pile of the above-mentioned embodiment, the application further provides an automatic control system of a bidirectional DC charging pile.

[0043] It should be noted that the bidirectional DC charging pile comprises a DC / DC module, a DC bus and a DC / AC module, wherein the first end of the DC / DC module is connected with the charging battery of the vehicle to be charged, the second end of the DC / DC module is connected with the first end of the DC bus, the second end of the DC bus is connected with the first end of the DC / AC module, and the second end of the DC / AC module is connected with the AC grid.

[0044] As Figure 6As shown, the automatic control system can include: a first acquisition unit 100, a generation unit 200 and a first control unit 300.

[0045] The first acquisition unit 100 is configured to acquire a first voltage reference value, a first current reference value, a first voltage actual value, a first current actual value and a virtual impedance value input / output by a direct-current gun head of the charging pile; the generation unit 200 is configured to generate a first PWM control signal according to the first voltage reference value, the first current reference value, the first voltage actual value, the first current actual value and the virtual impedance value; and the first control unit 300 is configured to, after receiving a charging instruction, control the DC / DC module to output a first demand voltage to the charging battery according to the first PWM control signal, or, after receiving a discharging instruction, control the DC / DC module to output a second demand voltage to the direct-current bus according to the first PWM control signal.

[0046] It can be understood that the first acquisition unit 100, the generation unit 200 and the first control unit 300 can be integrated in a first control chip, wherein the first control chip is responsible for DC / DC module detection, control and protection functions, and is responsible for outputting a voltage and a current required by a battery BMS at the vehicle end in a charging mode, and vice versa, charging the direct-current bus by the battery at the vehicle end in a discharging mode.

[0047] In an embodiment of the present application, the automatic control system of the bidirectional direct-current charging pile further includes a second acquisition unit and a second control unit (not specifically shown in the figure). The second acquisition unit acquires a bus voltage reference value, a bus voltage actual value and a zero-sequence current modulation component, generates a second PWM control signal according to the bus voltage reference value, the bus voltage actual value and the zero-sequence current modulation component, and the second control unit is configured to, after receiving a charging instruction, control the DC / AC module to output a third demand voltage to the direct-current bus according to the second PWM control signal, or, after receiving a discharging instruction, control the DC / AC module to output a fourth demand voltage to the alternating-current power grid according to the second PWM control signal.

[0048] It can be understood that the second acquisition unit and the second control unit can be integrated in a second control chip, and the second control chip is responsible for DC / AC module, direct-current bus detection, control and protection functions. In addition to the basic charging and discharging functions, the second control chip can execute corresponding national grid connection standards according to preset national parameters in a discharging mode, and has a power grid support capability. The first control chip and the second control chip exchange information through serial communication, and complete charging pile start / stop, protection, data upload / download functions.

[0049] In an embodiment of the present application, the generating unit 200 is specifically configured to: obtain a first voltage deviation value according to the first voltage reference value and the first voltage actual value; obtain a second current actual value according to the first current actual value and the virtual impedance value; obtain a first current deviation value according to the second current actual value and the first current reference value; perform PI adjustment on the first voltage deviation value and the first current deviation value respectively to obtain a first adjusted voltage value and a first adjusted current value; and generate the first PWM control signal according to the first adjusted voltage value and the first adjusted current value.

[0050] In an embodiment of the present application, the first obtaining unit 100 is specifically configured to: obtain a second voltage deviation value according to the bus voltage reference value and the bus voltage actual value; perform impedance transformation on the second voltage deviation value by using a first virtual impedance coefficient to generate a transient virtual impedance; obtain a power reference value and a power actual value of the DC / DC module input / output; obtain a power deviation value according to the power reference value and the power actual value; perform impedance transformation on the power deviation value by using a second virtual impedance coefficient to generate a steady-state virtual impedance; and perform superposition operation on the transient virtual impedance and the steady-state virtual impedance to obtain the virtual impedance value.

[0051] In an embodiment of the present application, the second obtaining unit is specifically configured to: obtain three-phase current actual values and three-phase current reference values of three-phase grid-connected currents during the discharging process of the bidirectional DC charging pile; superimpose the three-phase current actual values to obtain a zero-sequence current feedback value, and superimpose the three-phase current reference values to obtain a zero-sequence current reference value; obtain a zero-sequence current deviation value according to the zero-sequence current feedback value and the zero-sequence current reference value; and obtain the zero-sequence current modulation component by adjusting the zero-sequence current deviation value by using a proportional-resonant controller.

[0052] It should be noted that the specific embodiments of the automatic control system of the bidirectional DC charging pile of the present application can refer to the embodiments of the automatic control method of the bidirectional DC charging pile described above, and will not be repeated here.

[0053] In summary, according to the automatic control system of the bidirectional direct-current charging pile of the embodiment of the present application, the first acquisition unit acquires the first voltage reference value, the first current reference value, the first voltage actual value, the first current actual value and the virtual impedance value input / output by the direct-current gun head of the charging pile, the generation unit generates the first PWM control signal according to the first voltage reference value, the first current reference value, the first voltage actual value, the first current actual value and the virtual impedance value, and the first control unit controls the DC / DC module to output the first demand voltage to the charging battery according to the first PWM control signal after receiving the charging instruction, or controls the DC / DC module to output the second demand voltage to the direct-current bus according to the first PWM control signal after receiving the discharging instruction. Therefore, the automatic switching of the charging and discharging modes can be realized, the state switching time is short, and the frequency and voltage regulation requirements of the power system can be met.

[0054] Corresponding to the above embodiment, the present application further provides a computer device.

[0055] The computer device of the embodiment of the present application comprises a memory, a processor and a computer program stored on the memory and executable on the processor, and when the processor executes the program, the automatic control method of the bidirectional direct-current charging pile of the above embodiment is realized.

[0056] The computer device of the embodiment of the present application can realize the automatic switching of the charging and discharging modes, the state switching time is short, and the frequency and voltage regulation requirements of the power system can be met.

[0057] Corresponding to the above embodiment, the present application further provides a non-transitory computer readable storage medium.

[0058] The non-transitory computer readable storage medium of the embodiment of the present application stores a computer program, and when the program is executed by the processor, the automatic control method of the bidirectional direct-current charging pile of the above embodiment is realized.

[0059] The non-transitory computer readable storage medium of the embodiment of the present application can realize the automatic switching of the charging and discharging modes, the state switching time is short, and the frequency and voltage regulation requirements of the power system can be met.

[0060] In the description of the present application, the terms "first" and "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first" and "second" can explicitly or implicitly include one or more of the features. The meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0061] In the present application, unless specifically defined otherwise or limited in the specification, the terms "mount", "connected", "connection", "fixed", and the like, are used broadly and encompass both direct and indirect connections, mechanical and electrical connections, connections through intermediate media, and combinations thereof. The term "connected" is also meant to include the case where one or more intervening elements are present.

[0062] In the present application, unless specifically defined otherwise or limited in the specification, a first feature "on", "above", or "over" a second feature can be directly in contact with the second feature, or can be indirectly in contact with the second feature through an intervening medium. Also, a first feature "on", "above", or "over" a second feature can be vertically above the second feature, or can be laterally, or horizontally, above the second feature. A first feature "under", "below", or "underneath" a second feature can be vertically below the second feature, or can be laterally, or horizontally, below the second feature.

[0063] In the description of the specification, the description using the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the particular feature, structure, material or characteristic following the term is included in at least one embodiment or example of the present application. The illustrative expressions do not necessarily refer to the same embodiment or example, and the particular feature, structure, material or characteristic can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the features described in different embodiments or examples and the features of different embodiments or examples in the present specification without contradiction, if possible.

[0064] Any process or method descriptions or blocks in flow charts or otherwise described herein represent embodiments of the present application. It will be understood by those skilled in the art that, in some embodiments, certain acts, or blocks, or combinations thereof, can be performed by specific circuits, or by program instructions executed on a processor, or by a combination of both. The depictions of a certain act, or block, or combination thereof does not imply that the acts or blocks or combinations thereof must be performed in the order shown or discussed, but these can be performed in any order, or in parallel, or in any suitable order, as appropriate, unless otherwise specifically noted or dictated by the specification.

[0065] The logic and / or steps represented in flow diagrams or otherwise described herein, for example, can be considered as a sequence of instructions to implement logic functions, and can be embodied in any computer-readable medium for use by an instruction execution system, apparatus, or device, such as a computer-based system, processor- containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this specification, a "computer-readable medium" can be any means that can contain, store, communicate, propagate or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The computer-readable medium can be a machine-readable storage device (e.g., magnetic, optical or other) a machine-readable storage diskette (e.g., floppy, flexible or other), a machine-readable storage card (e.g., RAM, ROM or other), a machine-readable storage tape (e.g., magnetic, optical or other), a machine-readable storage medium (e.g., a portable memory chip), a machine-readable signal, a machine-readable propagated signal, a machine-readable compressed signal, and the like. More specific examples (a non-exhaustive list) of the computer-readable medium include the following: an electrical connection having one or more wires (e.g., a bus that has thin film resistors for

[0066] It should be understood that aspects of the application can be implemented in hardware, software, firmware or combinations thereof. In the embodiments described above, various steps or methods can be implemented, in part, or in whole, in software, firmware, hardware, or combinations thereof. For example, if implemented in software, an example of which is illustrated in FIG. 8, the software implementation can be operated on a processor, or by a processor, such as the processor 802. The software that embodies the methods described above can be stored on a computer readable medium, such as the storage 804, before it is uploaded to the processor 802. The processor 802 then executes the sequences of instructions (e.g., the software) that embody the various methods to implement the processes described herein. In an alternative implementation, the methods can be implemented in discrete hardware components or firmware, or combinations of hardware, software and firmware. For example, the various steps can be implemented in a dedicated integrated circuit, a programmable logic array, a field programmable gate array, or the like.

[0067] Those of skill in the art would understand that information and signals can be represented using any of a variety of technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that can be referenced throughout the above description can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0068] In addition, each function unit in each embodiment of the present application can be integrated in one processing module, or each unit can be physically present separately, or two or more units can be integrated in one module. The integrated module can be realized in the form of hardware or in the form of a software function module. When the integrated module is realized in the form of a software function module and sold or used as an independent product, it can also be stored in a computer readable storage medium.

[0069] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. An automatic control method for a bidirectional DC charging pile, characterized in that, The bidirectional DC charging pile includes: a DC / DC module, a DC bus, and a DC / AC module. The first terminal of the DC / DC module is connected to the charging battery of the vehicle to be charged. The second terminal of the DC / DC module is connected to the first terminal of the DC bus. The second terminal of the DC bus is connected to the first terminal of the DC / AC module. The second terminal of the DC / AC module is connected to the AC power grid. The automatic control method includes: Obtain the first voltage reference value, first current reference value, first voltage actual value, first current actual value, and virtual impedance value of the DC gun head input / output of the charging pile; A first PWM control signal is generated based on the first voltage reference value, the first current reference value, the actual first voltage value, the actual first current value, and the virtual impedance value; wherein, a first voltage deviation value is obtained based on the first voltage reference value and the first actual first voltage value; a second actual current value is obtained based on the first actual current value and the virtual impedance value; a first current deviation value is obtained based on the second actual current value and the first current reference value; PI regulation is applied to the first voltage deviation value and the first current deviation value respectively to obtain a first regulated voltage value and a first regulated current value; and the first PWM control signal is generated based on the first regulated voltage value and the first regulated current value. Upon receiving a charging command, the DC / DC module is controlled to output a first required voltage to the charging battery according to the first PWM control signal; or, upon receiving a discharging command, the DC / DC module is controlled to output a second required voltage to the DC bus according to the first PWM control signal. The automatic control method for the bidirectional DC charging pile further includes: acquiring a bus voltage reference value, an actual bus voltage value, and a zero-sequence current modulation component; wherein acquiring the virtual impedance value includes: The second voltage deviation value is obtained based on the bus voltage reference value and the actual bus voltage value; The second voltage deviation value is transformed using a first virtual impedance coefficient to generate an instantaneous virtual impedance; Obtain the power reference value and actual power value of the DC / DC module input / output; The power deviation value is obtained based on the power reference value and the actual power value; The power deviation value is transformed using a second virtual impedance coefficient to generate a steady-state virtual impedance. The instantaneous virtual impedance and the steady-state virtual impedance are superimposed to obtain the virtual impedance value.

2. The automatic control method for a bidirectional DC charging pile according to claim 1, characterized in that, Also includes: A second PWM control signal is generated based on the bus voltage reference value, the actual bus voltage value, and the zero-sequence current modulation component; Upon receiving a charging command, the DC / AC module is controlled to output a third required voltage to the DC bus according to the second PWM control signal; or, upon receiving a discharging command, the DC / AC module is controlled to output a fourth required voltage to the AC grid according to the second PWM control signal.

3. The automatic control method for a bidirectional DC charging pile according to claim 1, characterized in that, Obtaining the zero-sequence current modulation component includes: During the discharge process of the bidirectional DC charging pile, the actual value of the three-phase current and the reference value of the three-phase current are obtained. The actual values ​​of the three-phase currents are superimposed to obtain the zero-sequence current feedback value, and the reference values ​​of the three-phase currents are superimposed to obtain the zero-sequence current reference value. The zero-sequence current deviation value is obtained based on the zero-sequence current feedback value and the zero-sequence current reference value; A proportional resonant controller is used to adjust the zero-sequence current deviation value to obtain the zero-sequence current modulation component.

4. An automatic control system for a bidirectional DC charging pile according to any one of claims 1-3, characterized in that, The bidirectional DC charging pile includes: a DC / DC module, a DC bus, and a DC / AC module. The first terminal of the DC / DC module is connected to the charging battery of the vehicle to be charged. The second terminal of the DC / DC module is connected to the first terminal of the DC bus. The second terminal of the DC bus is connected to the first terminal of the DC / AC module. The second terminal of the DC / AC module is connected to the AC power grid. The automatic control system includes: The first acquisition unit is used to acquire the first voltage reference value, the first current reference value, the first voltage actual value, the first current actual value, and the virtual impedance value of the DC gun head input / output of the charging pile. A generation unit is configured to generate a first PWM control signal based on a first voltage reference value, a first current reference value, a first actual voltage value, a first actual current value, and a virtual impedance value. Specifically, the generation unit is configured to: obtain a first voltage deviation value based on the first voltage reference value and the first actual voltage value; obtain a second actual current value based on the first actual current value and the virtual impedance value; obtain a first current deviation value based on the second actual current value and the first current reference value; perform PI regulation on the first voltage deviation value and the first current deviation value respectively to obtain a first regulated voltage value and a first regulated current value; and generate the first PWM control signal based on the first regulated voltage value and the first regulated current value. A first control unit is configured to, upon receiving a charging command, control the DC / DC module to output a first required voltage to the rechargeable battery according to the first PWM control signal; or, upon receiving a discharging command, control the DC / DC module to output a second required voltage to the DC bus according to the first PWM control signal; wherein, the automatic control system of the bidirectional DC charging pile further includes: The second acquisition unit is used to acquire the bus voltage reference value, the actual bus voltage value, and the zero-sequence current modulation component; wherein, the first acquisition unit is specifically used for: The second voltage deviation value is obtained based on the bus voltage reference value and the actual bus voltage value; The second voltage deviation value is transformed using a first virtual impedance coefficient to generate an instantaneous virtual impedance; Obtain the power reference value and actual power value of the DC / DC module input / output; The power deviation value is obtained based on the power reference value and the actual power value; The power deviation value is transformed using a second virtual impedance coefficient to generate a steady-state virtual impedance. The instantaneous virtual impedance and the steady-state virtual impedance are superimposed to obtain the virtual impedance value.

5. The automatic control system for the bidirectional DC charging pile according to claim 4, characterized in that, Also includes: The second control unit, wherein... The second acquisition unit is further configured to generate a second PWM control signal based on the bus voltage reference value, the actual bus voltage value, and the zero-sequence current modulation component; The second control unit is used to control the DC / AC module to output a third required voltage to the DC bus according to the second PWM control signal after receiving a charging command, or to control the DC / AC module to output a fourth required voltage to the AC grid according to the second PWM control signal after receiving a discharging command.

6. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the automatic control method for bidirectional DC charging piles according to any one of claims 1-3.

7. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by the processor, the program implements the automatic control method for the bidirectional DC charging pile according to any one of claims 1-3.

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