Control method of three-phase AC / DC converter and power equipment

Abstract

The invention relates to a control method for a three-phase AC / DC converter, and the method comprises the steps: carrying out the DQ conversion through an AC-side power parameter, a rated frequency value of two on-load phase live wires of split-phase output, and a rated total voltage, and obtaining a d-axis given voltage and a q-axis given voltage which are compatible with a three-phase output control loop; a d-axis feedback component and a q-axis feedback component are determined according to the instantaneous output of the two on-load phase live wires, and then alternating current driving a three-phase alternating current-direct current converter to output a phase angle difference of 180 degrees at the two on-load phase live wires of split-phase output is generated according to the d-axis given voltage, the q-axis given voltage, the d-axis feedback component and the q-axis feedback component. A DQ control loop used by three-phase input is compatible, the same control loop can be used for controlling the three-phase AC / DC converter to carry out split-phase output and three-phase output, the compatibility is improved, and the system design and maintenance cost is reduced.

Description

Technical Field

[0001] This application belongs to the field of power electronics technology, and particularly relates to a control method for a three-phase AC-DC converter and a power device. Background Art

[0002] For a three-phase power converter, the voltage source characteristic is achieved through droop control. Moreover, when the three-phase power converter is configured to have split-phase input / output, it can be compatible with more usage scenarios. The conventional split-phase control method for a power converter is to perform droop control on the two input / output paths separately. However, this control method will cause a deviation in the phase angles of the two-phase voltages that is not 180° out of phase, resulting in poor compatibility with power generation equipment and off-grid loads. At the same time, the related split-phase control method uses sinusoidal control, which is based on AC quantities and cannot be unified with the control strategy based on direct current quantities on the DQ axes when there is three-phase input / output, leading to a complex system and increasing the design and maintenance costs of the system. Summary of the Invention

[0003] The purpose of this application is to provide a control method for a three-phase AC-DC converter and a power device, aiming to solve the problems of poor compatibility and complex system in the conventional split-phase control method for a three-phase power converter.

[0004] In a first aspect, an embodiment of this application provides a control method for a three-phase AC-DC converter. One of the live wires on the AC side of the three-phase AC-DC converter is left floating, and the other two live wires are used as two load-carrying live wires to connect to a load. The control method includes:

[0005] Obtain the AC-side power parameters of the three-phase AC-DC converter;

[0006] Obtain the d-axis reference voltage and q-axis reference voltage based on the AC-side power parameters, the rated frequency value of the two load-carrying live wires, and the rated total voltage of the two load-carrying live wires;

[0007] Determine the d-axis feedback component and q-axis feedback component based on the instantaneous output of the two load-carrying live wires;

[0008] Generate a drive signal based on the d-axis reference voltage, the q-axis reference voltage, the d-axis feedback component, and the q-axis feedback component. The drive signal is used to drive the three-phase AC-DC converter to output alternating current with a phase difference of 180° on the two load-carrying live wires.

[0009] In one embodiment, generating the drive signal based on the d-axis reference voltage, the q-axis reference voltage, the d-axis feedback component, and the q-axis feedback component includes:

[0010] Generate a d-axis modulation voltage based on the d-axis reference voltage and the d-axis feedback component;

[0011] Generate a q-axis modulation voltage based on the q-axis reference voltage and the q-axis feedback component;

[0012] Generate the drive signal based on the d-axis modulation voltage and the q-axis modulation voltage.

[0013] In one embodiment, the determining the d-axis feedback component and the q-axis feedback component according to the instantaneous output of the live-phase line includes:

[0014] Configure an orthogonal virtual signal of the instantaneous output based on the instantaneous output of the live-phase line;

[0015] Perform a coordinate transformation on the instantaneous output and the orthogonal virtual signal to obtain the d-axis feedback component and the q-axis feedback component.

[0016] In one embodiment, the d-axis feedback component includes a d-axis feedback voltage and a d-axis feedback current, and the q-axis feedback component includes a q-axis feedback voltage and a q-axis feedback current;

[0017] The generating the d-axis modulation voltage according to the d-axis reference voltage and the d-axis feedback voltage includes:

[0018] Obtain a d-axis reference current according to the difference between the d-axis reference voltage and the d-axis feedback component;

[0019] Obtain the d-axis modulation voltage according to the difference between the d-axis reference current and the d-axis feedback current;

[0020] The generating the q-axis modulation voltage according to the q-axis reference voltage and the q-axis feedback voltage includes:

[0021] Obtain a q-axis reference current according to the difference between the q-axis reference voltage and the q-axis feedback voltage;

[0022] Obtain the q-axis modulation voltage according to the difference between the q-axis reference current and the q-axis feedback current.

[0023] In one embodiment, the three-phase AC-DC converter includes a first bridge arm and a second bridge arm respectively connected to two live-phase lines; the generating the drive signal according to the d-axis modulation voltage and the q-axis modulation voltage includes:

[0024] Obtain an α-axis voltage through an inverse Park transformation according to the d-axis modulation voltage and the q-axis modulation voltage;

[0025] Obtain a first voltage modulation wave and a second voltage modulation wave according to the α-axis voltage;

[0026] Obtain the first drive signal of the first bridge arm and the second drive signal of the second bridge arm according to the first voltage modulation wave, the second voltage modulation wave, and a preset modulation strategy.

[0027] In one embodiment, the three-phase AC-DC converter further includes a third bridge arm connected to a suspended live wire phase, and the method further includes:

[0028] Stop outputting the drive signal for driving the third bridge arm.

[0029] In one embodiment, the AC-side power parameters include the given active power, actual active power, given reactive power, and actual reactive power of the two loaded live wire phases;

[0030] The obtaining of the d-axis given voltage and q-axis given voltage according to the AC-side power parameters, the rated frequency values of the two loaded live wire phases, and the rated total voltage of the two loaded live wire phases includes:

[0031] Obtain the given voltage amplitude value according to the given active power of the two loaded live wire phases, the actual active power of the two loaded live wire phases, and the rated total voltage of the loaded live wire phases;

[0032] Obtain the given voltage phase angle value according to the given reactive power of the two loaded live wire phases, the actual reactive power of the two loaded live wire phases, and the rated frequency values of the two loaded live wire phases;

[0033] Calculate the d-axis given voltage and q-axis given voltage according to the given voltage amplitude value and the given voltage phase angle value.

[0034] In one embodiment, the AC-side power parameters include the first given active power of the first phase in the first loaded live wire phase and the second given active power of the second loaded live wire phase, and the obtaining of the first voltage modulation wave and the second voltage modulation wave according to the α-axis voltage includes:

[0035] Determine the first voltage distribution coefficient of the first phase and the second voltage distribution coefficient of the second phase according to a preconfigured droop coefficient, the first given active power, and the second given active power;

[0036] Determine the first voltage modulation wave according to the α-axis voltage and the first voltage distribution coefficient;

[0037] Determine the second voltage modulation wave according to the α-axis voltage and the second voltage distribution coefficient; wherein, the phases of the first voltage modulation wave and the second voltage modulation wave differ by 180 degrees.

[0038] In a second aspect, an embodiment of the present application further provides a power device, including a three-phase AC-DC converter, a memory, a processor, and a computer program stored in the memory and executable on the processor. One of the live wires on the AC side of the three-phase AC-DC converter is left floating, and the other two live wires are used as loaded live wires to connect to other power devices respectively. The three-phase AC-DC converter is connected to the processor, and when the processor executes the computer program, the steps of the control method of the three-phase AC-DC converter as described above are implemented.

[0039] In a third aspect, an embodiment of the present application further provides a computer-readable storage medium, which stores a computer program, and when the computer program is executed by a controller, the steps of the control method of the three-phase AC-DC converter as described above can be implemented.

[0040] The beneficial effects of the embodiments of the present application compared with the related technologies are as follows:

[0041] The control method for split-phase output of the three-phase AC-DC converter provided by the embodiments of the present application performs DQ conversion on the AC side power parameters, the rated frequency values of the two loaded live wires for split-phase output, and the rated total voltage to obtain the d-axis given voltage and the q-axis given voltage. The d-axis feedback component and the q-axis feedback component are determined from the instantaneous outputs of the two loaded live wires, and then the d-axis given voltage, the q-axis given voltage, the d-axis feedback component, and the q-axis feedback component are used to generate a drive for the three-phase AC-DC converter to output alternating current with a phase angle difference of 180° between the two loaded live wires for split-phase output. In this way, it is compatible with the DQ control loop used for three-phase input, and the same control loop can be used to control the three-phase AC-DC converter for split-phase output and three-phase output, improving compatibility and reducing system design and maintenance costs. Description of the Drawings

[0042] Figure 1 It is a circuit schematic diagram of a three-phase AC-DC converter provided by an embodiment of the present application;

[0043] Figure 2 It is a flowchart of the control method of a three-phase AC-DC converter provided by an embodiment of the present application;

[0044] Figure 3 It is a control loop diagram of the control method of a three-phase AC-DC converter provided by an embodiment of the present application;

[0045] Figure 4 It is a virtual quantity calculation loop diagram of the control method of a three-phase AC-DC converter provided by an embodiment of the present application;

[0046] Figure 5 It is a flowchart of the control method of a three-phase AC-DC converter provided by an embodiment of the present application;

[0047] Figure 6 Schematic diagram of the modules of the control device of the bidirectional AC-DC converter provided by an embodiment of the present application;

[0048] Figure 7 Schematic diagram of the structure of the power equipment provided by an embodiment of the present application. Detailed implementation manners

[0049] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer and more understandable, the present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0050] It should be noted that when an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0051] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, "a plurality of" means two or more unless otherwise specifically defined.

[0052] As Figure 1 shown, the three-phase bidirectional AC / DC converter 100 includes an AC / DC conversion circuit 110 and a filtering circuit 120. The first end of the filtering circuit 120 is connected to the AC side of the AC / DC conversion circuit 110. The second end of the filtering circuit 120 serves as the AC side of the three-phase bidirectional AC / DC converter 100. The DC side of the AC / DC conversion circuit 110 serves as the DC side of the three-phase bidirectional AC / DC converter 100. The filtering circuit 120 includes filtering capacitors C f1 , C f2 , C f3 and filtering inductors L1 to L3.

[0053] In the example, the main topology of the AC / DC conversion circuit 110 adopts a T-type three-level inverter circuit. The DC side of the T-type three-level inverter circuit is the DC bus BUS+ / BUS-, and an upper bus capacitor C BUS1 and a lower bus capacitor C BUS2, the midpoint of the busbar is point O. The DC side of the three-phase AC-DC converter 100 can also be connected to a buck-boost circuit to achieve maximum power point tracking (MPPT) or connected to other DC power sources, such as energy storage batteries. The DC side of the three-phase AC-DC converter 100 can also be connected to a balance bridge circuit to balance the potential of the busbar midpoint O. The AC side of the T-type three-level inverter circuit is a filter circuit 120 (such as Figure 1 the inductor L1 and capacitor C in phase A in f1 ). The filter circuit 120 is provided on each phase output line of the T-type three-level inverter circuit. After the output of the T-type three-level inverter circuit passes through the filter circuit 120, it is connected to the load LOAD and / or the power grid GRID, other AC power sources such as smart generators, etc.

[0054] In some application scenarios, the three-phase device including the three-phase AC-DC converter 100 can be changed into a split-phase device. For example, for a split-phase device, it is required to achieve one-phase charging and one-phase discharging, and at the same time, the phase angles of the two-phase voltages are required to differ by 180°. However, currently, when changing a three-phase device into a split-phase device, if the droop control is used for the two live wires of the split-phase output (such as phase A and phase B), the angle will deviate. Therefore, there is currently no unified droop control strategy, and current source parallel connection is generally used, which cannot be well compatible with smart generators and off-grid systems. At the same time, the split-phase uses sinusoidal control in terms of control, which cannot be unified with the DQ-axis-based control of the three-phase.

[0055] When changing the three-phase device including the three-phase AC-DC converter 100 into a split-phase device, one of the live wires on the AC side of the three-phase AC-DC converter 100 can be left floating (such as phase C), and the other live wires (such as phase A and phase B) are used as the two live wires with load to connect to the load. It can be understood that at this time, the switching tubes in the AC / DC conversion circuit 110 corresponding to the floating live wire (such as phase C) can be blocked.

[0056] Among them, in the AC / DC conversion circuit 110 as shown in Figure 1 , the bridge arm connected to the first live wire with load is defined as the first bridge arm, the bridge arm connected to the second live wire with load is defined as the second bridge arm, and the first bridge arm includes transistors Q a1 -Q a4 , the second bridge arm includes transistors Q b1 -Q b4 . The bridge arm connected to the floating live wire is defined as the third bridge arm, and the third bridge arm includes transistors Q c1 -Q c4 .

[0057] It can be understood that Figure 1The shown AC / DC conversion circuit 110 is only schematic. Exemplarily, the AC / DC conversion circuit 110 can also be a type-I three-level inverter circuit, a three-phase bridge inverter circuit, etc. The present application does not limit the topology type of the AC / DC conversion circuit.

[0058] Based on this, an embodiment of the present application provides a control method for a three-phase AC-DC converter to solve this problem. Please refer to Figure 1 and Figure 2 . The control method includes:

[0059] Step S110, obtaining the AC-side power parameters of the three-phase AC-DC converter.

[0060] Among them, the voltage and current detection circuit can be used to detect the voltage and current on the AC side of the three-phase AC-DC converter 100 in real time or periodically to obtain the AC-side power parameters. It should be noted that the AC-side power parameters include the actual active power P i and the actual reactive power Q i .

[0061] Step S120, obtaining the d-axis reference voltage and q-axis reference voltage according to the AC-side power parameters, the rated frequency values of the two loaded phase live wires, and the rated total voltage of the loaded phase live wire.

[0062] Among them, in order to make the control strategy of split-phase output compatible with the three-phase output control strategy, according to the three-phase droop control strategy, the reference active power P ref and the reference reactive power Q ref of the two loaded phase live wires are configured.

[0063] After that, according to the reference active power P ref , the actual active power P i , and the rated total voltage V ref0 of the loaded phase live wire, the voltage amplitude reference value U ref is obtained. According to the reference reactive power flat Q ref , the actual reactive power Q i , and the rated frequency value f0 of the two loaded phase live wires, the voltage phase angle reference value θ is obtained, that is, the reference angle output by the droop control Q axis. Among them, it should be noted that in the split-phase output power grid, the line voltage is equal to 2 times the phase voltage. Then the rated total voltage V ref0 of the two loaded phase live wires is the sum of the amplitudes of the voltages of the two loaded phase live wires, such as 230V. The rated frequency value f0 of the loaded phase live wire is, for example, 50hz.

[0064] Finally, the d-axis reference voltage U ref and the q-axis reference voltage U dref are obtained through dq conversion according to the voltage amplitude reference value Uqref 。

[0065] Step S130: Determine the d-axis feedback component and the q-axis feedback component according to the instantaneous output of the two live-phase fire wires with load.

[0066] Based on the fact that the phase angles of the two live-phase fire wires with load in the split-phase output differ by 180°, borrowing the idea of converting from a two-phase stationary coordinate system to a two-phase rotating coordinate system (i.e., αβ-dq), assume that the voltage corresponding to the instantaneous output of the two live-phase fire wires with load is the α-axis voltage U α ,and then virtualize a β-axis voltage U with a phase difference of 90° β ,so as to realize the conversion of the αβ coordinate axis to the dq coordinate axis to obtain the d-axis feedback component and the q-axis feedback component, and thus realize the use of direct current to perform loop control.

[0067] Step S140: Generate a driving signal according to the d-axis given voltage, the q-axis given voltage, the d-axis feedback component, and the q-axis feedback component. The driving signal is used to drive the three-phase AC-DC converter to output alternating current with a phase difference of 180° between the two live-phase fire wires with load.

[0068] Among them, a preset control loop can be used to generate the driving signal, and the d-axis given voltage, the q-axis given voltage, the d-axis feedback component, and the q-axis feedback component are used as the input parameters of the preset control loop. Exemplarily, the preset control loop is the voltage outer loop and the current inner loop. According to the d-axis given voltage U dref 、the d-axis feedback component, the d-axis modulation voltage U is obtained through the voltage outer loop and the current inner loop dout ,according to the q-axis given voltage U qref 、the q-axis feedback component, the q-axis modulation voltage U is obtained through the voltage outer loop and the current inner loop qout ;According to the d-axis modulation voltage U dout and the q-axis modulation voltage U qout generate a driving signal.

[0069] For the control method of the three-phase AC-DC converter in the embodiment of the present application, since the instantaneous output of the two live-phase fire wires with load can be converted to the virtual DQ axis and share the same set of control strategies with the three-phase control, the compatibility is improved and the system design and maintenance costs are reduced. When connected to the grid and off the grid, droop control can be used respectively, and the two live-phase fire wires with load simultaneously meet the requirements of one-phase charging and one-phase discharging, that is, meet the split-phase output requirements.

[0070] It should be noted here that the solution of the present application can be applied to the scenario of multi-machine parallel connection. In the multi-machine parallel connection scenario, the given active power P of a single device ref is the average value P of the given active powers of all split-phase devices in parallel avg 。For example, split-phase device 1 and split-phase device 2 are in parallel, and the given active power of split-phase device 1 itself is P toal1, the given active power of the split-phase device 1 itself is P toal2 , after parallel operation, the given active powers of the split-phase device 1 and the split-phase device 1 are both P ref = P avg = (P toal1 + P toal2 ) / 2. In the single-machine scenario, the given active power P ref of a single device is the given active power of the split-phase device itself. For example, the given active power P ref of the split-phase device 1 toal1 = P ref . The given reactive power Q

[0071] is similar. ref and the given reactive power Q ref . In the scenario of multi-machine parallel operation, active and reactive power sharing can be achieved through this control method, avoiding parallel operation circulating current.

[0072] At the same time, the split-phase device adopting the technical solution of this application can also be connected in parallel with single-phase and split-phase intelligent generators, simultaneously meeting the voltage source characteristics of grid connection and off-grid. Among them, when connected in parallel with an intelligent generator, the live wire of the first loaded phase (such as phase A) is connected to the single-phase intelligent generator, and the live wire of the second loaded phase (such as phase B) is connected to the load; when connected in parallel with a split-phase intelligent generator, the live wires of the two loaded phases are respectively connected to the corresponding phase live wires of the split-phase intelligent generator.

[0073] In some embodiments, the control method of the three-phase AC-DC converter further includes: stopping the driving signal for driving the third bridge arm, thereby avoiding mis-triggering of the third bridge arm and making the floating-phase live wire charged.

[0074] It can be understood that this application is described by taking the preset control loop including a voltage loop and a current loop as an example. In other embodiments, the preset control loop may also only include a voltage loop or a current loop, or include a combination of other loops.

[0075] In some embodiments, step S140 includes:

[0076] Step S141, generating a d-axis modulation voltage according to the d-axis given voltage and the d-axis feedback component.

[0077] Specifically, if the preset control loop includes a voltage loop and a current loop, the d-axis feedback component includes the d-axis feedback voltage V dfeed and the d-axis feedback current I dfeed .

[0078] Please refer to Figure 3 , first, through the voltage loop of the d-axis, according to the d-axis given voltage U drefThe difference from the d-axis feedback component is used to obtain the d-axis reference current through deviation (e.g., PI, proportional integral) operation.

[0079] Secondly, through the current loop of the d-axis, according to the difference between the d-axis reference current and the d-axis feedback current I dfeed a d-axis modulation voltage U dout .

[0080] Step S142: Generate a q-axis modulation voltage based on the q-axis reference voltage and the q-axis feedback component;

[0081] Specifically, the q-axis feedback component includes the q-axis feedback voltage V qfeed and the q-axis feedback current I qfeed .

[0082] Please refer to Figure 3 , first, through the voltage loop of the q-axis, according to the difference between the q-axis reference voltage U qref and the q-axis feedback voltage V qfeed a q-axis reference current is obtained through deviation operation;

[0083] Secondly, through the current loop of the q-axis, according to the difference between the q-axis reference current and the q-axis feedback current I qfeed a q-axis modulation voltage U qout is obtained through deviation operation.

[0084] Step S143: Generate a drive signal based on the d-axis modulation voltage and the q-axis modulation voltage.

[0085] Among them, through the d-axis modulation voltage U dout and the q-axis modulation voltage U qout a reverse Park transformation is performed to obtain the α-axis voltage. According to the α-axis voltage U α , the first reference active power P1 of the first phase load-carrying phase wire, the second reference active power P2 of the second phase load-carrying phase wire, and the droop coefficient M, the first voltage modulation wave V1 PWM of the first phase and the second voltage modulation wave V2 PWM of the second phase can be calculated, and then a drive signal is obtained through modulation by a PWM controller (e.g., sinusoidal pulse width modulation SPWM).

[0086] In some embodiments, step S130 includes:

[0087] Step S131: Configure an orthogonal virtual signal of the instantaneous output based on the instantaneous output of the two load-carrying phase wires.

[0088] The instantaneous output of the two load-carrying phase live wires includes: the instantaneous voltage V1 of the first-phase load-carrying phase live wire; the instantaneous voltage V2 of the second-phase load-carrying phase live wire; the instantaneous current I1 of the first-phase load-carrying phase live wire; the instantaneous current I2 of the second-phase load-carrying phase live wire.

[0089] The quadrature virtual signals include: the virtual voltage V1*e that is 90° out of phase with V1 -jw , the virtual voltage V2*e that is 90° out of phase with V2 -jw , the virtual current I1*e that is 90° out of phase with I1 -jw , the virtual current I2*e that is 90° out of phase with I2 -jw .

[0090] Please refer to Figure 4 , the specific generation process of the voltage V1*e -jw can use the sogi algorithm. Among them, w0 is the grid angular frequency, is the integrator, and k is the filtering coefficient of the adjustable filter. The generation processes of other quadrature virtual signals are similar and will not be elaborated.

[0091] Step S132, perform coordinate transformation on the instantaneous output and the quadrature virtual signals to obtain the d-axis feedback component and the d-axis feedback component.

[0092] Specifically, the sum of the instantaneous outputs corresponds to the α-axis output, and the sum of the quadrature virtual signals of the instantaneous outputs corresponds to the β-axis output. For the above instantaneous output and quadrature virtual signals, based on the formula:

[0093]

[0094] Performing αβ-dq conversion can obtain the d-axis feedback voltage V dfeed , the d-axis feedback current I dfeed , the q-axis feedback voltage V qfeed and the q-axis feedback current I qfeed .

[0095] This transformation enables the control strategy to be implemented using direct current, enabling the three-phase AC-DC converter 100 to still use droop control during split-phase output and being compatible with the control strategy of three-phase output.

[0096] In some embodiments, step S143 includes:

[0097] Step S1431, obtain the α-axis voltage through Park inverse transformation according to the d-axis modulation voltage and the q-axis modulation voltage.

[0098] Specifically, the α-axis voltage U α can be calculated according to the following formula.

[0099]

[0100] Step S1432, according to the α-axis voltage U α to obtain the first voltage modulation wave and the second voltage modulation wave.

[0101] Specifically, the AC-side power parameters include the first given active power P1 of the first phase load-carrying phase live wire and the second given active power P2 of the second phase load-carrying phase live wire.

[0102] The first voltage modulation wave V1 pwm and the second voltage modulation wave V1 pwm are modulation waves for PWM modulation (such as unipolar SPWM modulation). According to the pre-configured droop coefficient M, the first given active power P1, and the second given active power P2 to determine P2 and the α-axis voltage U α the first voltage modulation wave V1 can be determined pwm and the second voltage modulation wave V2 pwm .

[0103] M can be a pre-configured droop coefficient, for example:

[0104]

[0105] wherein, P max is the maximum power allowed for the first phase load-carrying phase live wire, E0 is the rated voltage of the first phase in the first phase load-carrying phase live wire, and E min is the minimum voltage allowed for the first phase load-carrying phase live wire.

[0106] Step S1433, according to the first voltage modulation wave, the second voltage modulation wave, and a preset modulation strategy, obtain the first drive signal of the first bridge arm and the second drive signal of the second bridge arm.

[0107] Among them, the preset modulation strategy is determined according to the load or application scenario connected to the two load-carrying phase live wires, for example, adopting a unipolar modulation strategy. The PWM controller calculates the first drive signal of the first bridge arm and the second drive signal of the second bridge arm according to the first voltage modulation wave, the second voltage modulation wave, and the preset modulation strategy.

[0108] In some embodiments, step S1432 includes:

[0109] Step a, determine the first voltage distribution coefficient of the first phase and the second voltage distribution coefficient of the second phase according to the pre-configured droop coefficient M, the first given active power P1, and the second given active power P2.

[0110] Specifically, the first voltage distribution coefficient is 1 + 0.5 * (P1 - P2) / (P1 + P2) * M, and the second voltage distribution coefficient is -(1 + 0.5 * (P2 - P1) / (P1 + P2) * M).

[0111] Step b, determining a first voltage modulation wave according to the α-axis voltage and the first voltage distribution coefficient.

[0112] Specifically, the first voltage modulation wave V1 pwm = U α *(1 + 0.5*(P1 - P2) / (P1 + P2)*M).

[0113] Step c, determining a second voltage modulation wave according to the α-axis voltage and the second voltage distribution coefficient; wherein, the phases of the first voltage modulation wave and the second voltage modulation wave differ by 180 degrees.

[0114] Specifically, the second voltage modulation wave V2 pwm = -U α *(1 + 0.5*(P2 - P1) / (P1 + P2)*M).

[0115] In some embodiments, referring to Figure 3 and Figure 5 , step S110 includes:

[0116] Step S111, obtaining a given value of voltage amplitude according to the given active power of two live phase lines with load, the actual active power of two live phase lines with load, and the rated total voltage of two live phase lines with load.

[0117] Wherein, when the three-phase AC-DC converter 100 is connected in parallel with multiple other split-phase devices to form a multi-machine parallel connection, the average value of active power P avg is obtained according to the given active power of each parallel device, and the average value of active power P avg is used as the given active power P ref of two live phase lines with load. If the three-phase AC-DC converter 100 outputs independently, that is, operates as a single device, then the given active power P ref = the first given active power P1 + the second given active power P2.

[0118] Performing a deviation operation on the difference between the given active power P ref and the actual active power P i through a first PI controller to obtain the total voltage amplitude adjustment amount Δv of two live phase lines with load. Then, summing the total voltage amplitude adjustment amount Δv and the rated total voltage V ref0 of two live phase lines with load to obtain the given value U ref of voltage amplitude.

[0119] Step S112, obtaining a given value of voltage phase angle according to the given reactive power of two live phase lines with load, the actual reactive power of two live phase lines with load, and the rated frequency value of two live phase lines with load.

[0120] Similarly, when the three-phase AC-DC converter 100 is connected in parallel with multiple other split-phase devices to form a multi-machine parallel connection, the average reactive power Q is obtained according to the given reactive power of each parallel device. avg The average reactive power Q avg is used as the given reactive power Q of the two load-carrying phase live wires. ref If the three-phase AC-DC converter 100 outputs independently, that is, when operating as a single device, the given reactive power Q ref = the first given reactive power Q1 + the second given reactive power Q2.

[0121] The difference between the given reactive power Q ref and the actual reactive power Q i is subjected to deviation calculation through the second PI controller to obtain the frequency adjustment amount Δf of the two load-carrying phase live wires. Then, the frequency adjustment amount Δf is summed with the rated frequency value f0 of the two load-carrying phase live wires to obtain the frequency given value f ref , which is then converted into the voltage phase angle given value θ.

[0122] Step S113: Calculate the d-axis given voltage and the q-axis given voltage according to the voltage amplitude given value and the voltage phase angle given value.

[0123] According to the coordinate transformation from the three-phase stationary coordinate system to the two-phase stationary coordinate system, we get:

[0124] d-axis given voltage: U dref = U ref cos(θ);

[0125] q-axis given voltage: U qref = U ref sin(θ).

[0126] In this way, the split-phase output can be controlled in a control mode compatible with the three-phase output, that is, the droop control mode used in the three-phase output can be reused without configuring different control loops.

[0127] Please refer to Figure 6 , this application embodiment also provides a control device for a three-phase AC-DC converter, including:

[0128] An acquisition module 601, configured to acquire the AC-side power parameters of the three-phase AC-DC converter;

[0129] A first conversion module 602, configured to obtain the d-axis given voltage and the q-axis given voltage according to the AC-side power parameters, the rated frequency value of the two load-carrying phase live wires, and the rated total voltage of the two load-carrying phase live wires;

[0130] A second conversion module 603, configured to determine the d-axis feedback component and the q-axis feedback component according to the instantaneous output of the two load-carrying phase live wires;

[0131] A control module 604, configured to generate a driving signal according to the d-axis reference voltage, the q-axis reference voltage, the d-axis feedback component, and the q-axis feedback component, where the driving signal is used to drive the three-phase AC-DC converter to output alternating current with a phase difference of 180° between the live wires of the two loaded phases.

[0132] In one embodiment, the control module 604 includes:

[0133] A first loop, configured to generate a d-axis modulation voltage according to the d-axis reference voltage and the d-axis feedback component;

[0134] A second loop, configured to generate a q-axis modulation voltage according to the q-axis reference voltage and the q-axis feedback component;

[0135] A control unit, configured to generate the driving signal according to the d-axis modulation voltage and the q-axis modulation voltage.

[0136] In one embodiment, the second conversion module 603 includes:

[0137] A configuration unit, configured to configure an orthogonal virtual signal of the instantaneous output based on the instantaneous output of the live wires of the two loaded phases;

[0138] A first transformation unit, configured to perform a coordinate transformation on the instantaneous output and the orthogonal virtual signal to obtain a d-axis feedback component and a q-axis feedback component.

[0139] In one embodiment, the d-axis feedback component includes a d-axis feedback voltage and a d-axis feedback current, and the q-axis feedback component includes a q-axis feedback voltage and a q-axis feedback current;

[0140] The first loop includes:

[0141] A first voltage loop, configured to obtain a d-axis reference current according to the difference between the d-axis reference voltage and the d-axis feedback component;

[0142] A first current loop, configured to obtain the d-axis modulation voltage according to the difference between the d-axis reference current and the d-axis feedback current;

[0143] The second loop includes:

[0144] A second voltage loop, configured to obtain a q-axis reference current according to the difference between the q-axis reference voltage and the q-axis feedback voltage;

[0145] A second current loop, configured to obtain the q-axis modulation voltage according to the difference between the q-axis reference current and the q-axis feedback current.

[0146] In one embodiment, the three-phase AC-DC converter includes a first bridge arm and a second bridge arm respectively connected to the live-phase fire wires of the two loaded phases; the control unit includes:

[0147] A converter, configured to obtain the α-axis voltage through Park inverse transformation according to the d-axis modulation voltage and the q-axis modulation voltage;

[0148] A calculator, configured to obtain a first voltage modulation wave and a second voltage modulation wave according to the α-axis voltage;

[0149] A controller, configured to obtain a first driving signal of the first bridge arm and a second driving signal of the second bridge arm according to the first voltage modulation wave, the second voltage modulation wave, and a preset modulation strategy.

[0150] In one embodiment, the three-phase AC-DC converter further includes a third bridge arm connected to the floating live-phase fire wire, and the control module 604 is further configured to:

[0151] Stop outputting the driving signal for driving the third bridge arm.

[0152] In one embodiment, the AC-side power parameters include the given active power, the actual active power, the given reactive power, and the actual reactive power of the live-phase fire wires of the two loaded phases; the first conversion module 602 includes:

[0153] An active power control loop, configured to obtain a given voltage amplitude value according to the given active power of the live-phase fire wires of the two loaded phases, the actual active power of the live-phase fire wires of the two loaded phases, and the rated total voltage of the live-phase fire wires of the two loaded phases;

[0154] A reactive power control loop, configured to obtain a given voltage phase angle value according to the given reactive power of the live-phase fire wires of the two loaded phases, the actual reactive power of the live-phase fire wires of the two loaded phases, and the rated frequency value of the live-phase fire wires of the two loaded phases;

[0155] A second transformation unit, configured to calculate and obtain the given d-axis voltage and the given q-axis voltage according to the given voltage amplitude value and the given voltage phase angle value.

[0156] In one embodiment, the AC-side power parameters include the first given active power of the first phase in the first live-phase fire wire and the second given active power of the second live-phase fire wire, and the calculator includes:

[0157] A first calculation sub-unit, configured to determine a first voltage distribution coefficient of the first phase and a second voltage distribution coefficient of the second phase according to a pre-configured droop coefficient, the first given active power, and the second given active power;

[0158] A second calculation subunit determines the first voltage modulation wave according to the α-axis voltage and the first voltage distribution coefficient;

[0159] A third calculation subunit determines the second voltage modulation wave according to the α-axis voltage and the second voltage distribution coefficient; wherein, the phases of the first voltage modulation wave and the second voltage modulation wave differ by 180 degrees.

[0160] For the specific implementation manners and related beneficial effects of the control device of the above three-phase AC-DC converter, please refer to the description of the specific embodiments of the control method of the above three-phase AC-DC converter, which will not be elaborated here.

[0161] Please refer to Figure 7 , this application embodiment also provides a power device 70. The power device 70 includes a three-phase AC-DC converter 100, a memory 72, a processor 73, and a computer program 721 stored in the memory 72 and operable on the processor 73. One of the live wires of the AC side of the three-phase AC-DC converter 100 is left floating, and the other two live wires are used as two loaded-phase live wires to connect other power devices respectively. The three-phase AC-DC converter 100 is also connected to the processor 73. When the processor 73 executes the computer program 721, the steps of the control method of the three-phase AC-DC converter as described above are implemented.

[0162] It can be understood that the power device 70 can be a separate power device, or an energy storage device with a battery module 20 and a power module, or can be an energy storage system including a power device and multiple battery modules 20.

[0163] Those skilled in the art can understand that Figure 7 merely examples of the power device 70, which do not constitute a limitation to the power device 70, and may include more or fewer components than shown in the figure, or combine certain components, or different components. For example, it may also include input / output devices, network access devices, etc.

[0164] The processor 73 can be a central processing unit (CPU), and the processor 73 can also be other general controllers, DSPs, application specific integrated circuits (ASICs), FPGAs or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general controller can be a microcontroller or any conventional controller.

[0165] The memory 72 can be an internal storage unit of the power device 70 in some embodiments, such as the hard disk or memory of the power device 70. The memory 72 can also be an external storage device of the power device 70 in other embodiments, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, etc. equipped on the power device 70. Further, the memory 72 can also include both the internal storage unit of the power device 70 and the external storage device. The memory 72 is used to store the operating system, application programs, Boot Loader, data, and other programs, etc. The memory 72 can also be used to temporarily store the data that has been output or will be output.

[0166] An embodiment of the present application also provides a computer-readable storage medium storing a computer program 721, and when the computer program 721 is executed by a processor 73, the steps in the above method embodiments can be implemented.

[0167] An embodiment of the present application provides a computer program product, which when running on a computer, causes the computer to execute the steps in the above method embodiments.

[0168] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, to implement all or part of the processes in the above method embodiments of the present application, the computer program 721 can be used to instruct the relevant hardware to complete. The computer program 721 can be stored in a computer-readable storage medium. When the computer program 721 is executed by the processor 73, the steps in the above method embodiments can be implemented. Wherein, the computer program 721 includes computer program 721 code, and the computer program 721 code can be in the form of source code, object code, executable file, or some intermediate form, etc. The computer-readable medium can at least include: any entity or device capable of carrying the computer program 721 code to the photographing device / terminal device, a recording medium, a computer memory 72, a ROM (Read-Only Memory, read-only memory 72), a RAM (Random Access Memory, random access memory 72), a CD-ROM (Compact Disc Read-Only Memory, read-only optical disc), magnetic tape, floppy disk, and optical data storage device, etc. The computer-readable storage medium mentioned in the present application can be a non-volatile storage medium, in other words, it can be a non-transitory storage medium.

[0169] It should be understood that all or part of the steps of implementing the above embodiments can be realized by software, hardware, firmware, or any combination thereof. When implemented using software, it can be realized in whole or in part in the form of a computer program product 721. The computer program product 721 includes one or more computer instructions. These computer instructions can be stored in the above computer-readable storage medium.

[0170] In the above embodiments, the descriptions of the various embodiments have their own emphases. For the parts not detailed or recorded in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0171] Those of ordinary skill in the art can realize that the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this application.

[0172] In the embodiments provided in this application, it should be understood that the disclosed devices / electronic devices and methods can be implemented in other ways. For example, the device / electronic device embodiments described above are only illustrative. For example, the division of modules or units is only a logical function division. In actual implementation, there can be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces. The indirect couplings or communication connections of the devices or units can be in electrical, mechanical, or other forms.

[0173] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place, or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0174] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. And these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included in the protection scope of this application.

Claims

1. A control method for a three-phase AC / DC converter, characterized in that: One phase live wire of the AC side of the three-phase AC / DC converter is suspended, and the other two phase live wires are used as two load-carrying phase live wires for connecting loads. The control method includes: Acquiring AC side power parameters of the three-phase AC / DC converter; Obtaining a d-axis given voltage and a q-axis given voltage according to the AC side power parameter, the rated frequency value of the two phase-carrying live wires and the rated total voltage of the two phase-carrying live wires; Determine the d-axis feedback component and the q-axis feedback component according to the instantaneous output of the two phase-carrying live wires; A driving signal is generated according to the d-axis given voltage, the q-axis given voltage, the d-axis feedback component and the q-axis feedback component, wherein the driving signal is used to drive the three-phase AC / DC converter to output AC power with a phase difference of 180° on the two phase-carrying live wires.

2. The control method according to claim 1, characterized in that: The generating a driving signal according to the d-axis given voltage, the q-axis given voltage, the d-axis feedback component and the q-axis feedback component comprises: Generate a d-axis modulation voltage according to the d-axis given voltage and the d-axis feedback component; Generate a q-axis modulation voltage according to the q-axis given voltage and the q-axis feedback component; The driving signal is generated according to the d-axis modulation voltage and the q-axis modulation voltage.

3. The control method according to claim 1, characterized in that: The step of determining the d-axis feedback component and the q-axis feedback component according to the instantaneous output of the two phase-carrying live wires comprises: configuring the instantaneous output orthogonal virtual signal based on the instantaneous output of the two phase-carrying live wires; Coordinate transformation is performed on the instantaneous output and the orthogonal virtual signal to obtain a d-axis feedback component and a d-axis feedback component.

4. The control method according to claim 2, characterized in that: The d-axis feedback component includes a d-axis feedback voltage and a d-axis feedback current, and the q-axis feedback component includes a q-axis feedback voltage and a q-axis feedback current; The generating the d-axis modulation voltage according to the d-axis given voltage and the d-axis feedback voltage comprises: Obtaining a d-axis given current according to a difference between the d-axis given voltage and the d-axis feedback component; Obtaining the d-axis modulation voltage according to the difference between the d-axis given current and the d-axis feedback current; The generating the q-axis modulation voltage according to the q-axis given voltage and the q-axis feedback voltage comprises: Obtaining a q-axis given current according to a difference between the q-axis given voltage and the q-axis feedback voltage; The q-axis modulation voltage is obtained according to the difference between the q-axis given current and the q-axis feedback current.

5. The control method according to claim 2, characterized in that: The three-phase AC / DC converter comprises a first bridge arm and a second bridge arm respectively connected to two phase-carrying live wires; the driving signal is generated according to the d-axis modulation voltage and the q-axis modulation voltage, comprising: Obtaining an α-axis voltage by Park inverse transformation according to the d-axis modulation voltage and the q-axis modulation voltage; Obtaining a first voltage modulation wave and a second voltage modulation wave according to the α-axis voltage; A first driving signal for the first bridge arm and a second driving signal for the second bridge arm are obtained according to the first voltage modulation wave, the second voltage modulation wave and a preset modulation strategy.

6. The control method according to any one of claims 1 to 5, characterized in that: The three-phase AC / DC converter further includes a third bridge arm connected to a suspended live wire of one phase, and the method further includes: Stop outputting the driving signal for driving the third bridge arm.

7. The control method according to any one of claims 1 to 5, characterized in that: The AC side power parameters include the given active power, actual active power, given reactive power and actual reactive power of the two phase-carrying live wires; The step of obtaining the d-axis given voltage and the q-axis given voltage according to the AC side power parameter, the rated frequency value of the two phase-carrying live wires, and the rated total voltage of the two phase-carrying live wires includes: Obtaining a given voltage amplitude value according to given active powers of the two phase-carrying live wires, actual active powers of the two phase-carrying live wires and rated total voltages of the two phase-carrying live wires; Obtaining a voltage phase angle given value according to given reactive powers of the two phase-carrying live wires, actual reactive powers of the two phase-carrying live wires and rated frequency values ​​of the two phase-carrying live wires; The d-axis given voltage and the q-axis given voltage are calculated according to the voltage amplitude given value and the voltage phase angle given value.

8. The control method according to claim 5, wherein the AC side power parameter comprises a first given active power of a first phase live wire and a second given active power of a second phase live wire, and the first voltage modulation wave and the second voltage modulation wave obtained according to the α-axis voltage comprise: Determine a first voltage distribution coefficient of the first phase and a second voltage distribution coefficient of the second phase according to a preconfigured droop coefficient, the first given active power, and the second given active power; determining the first voltage modulation wave according to the α-axis voltage and the first voltage distribution coefficient; The second voltage modulation wave is determined according to the α-axis voltage and the second voltage distribution coefficient; wherein the first voltage modulation wave and the second voltage modulation wave have a phase difference of 180 degrees.

9. An electric power device, characterized in that: The invention comprises a three-phase AC / DC converter, a memory, a processor and a computer program stored in the memory and executable on the processor, wherein one phase live wire of the AC side of the three-phase AC / DC converter is suspended, and the other two phase live wires are used as two phase live wires with loads to connect other power equipment respectively, the three-phase AC / DC converter is connected to the processor, and the processor implements the steps of the control method of the three-phase AC / DC converter according to any one of claims 1 to 8 when executing the computer program.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by the controller, the steps of the control method of the three-phase AC-DC converter as claimed in any one of claims 1 to 8 can be implemented.

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