Parallel system current sharing control method and parallel system

Abstract

The application provides a current sharing control method of a parallel system and the parallel system. The parallel system comprises at least two parallel devices. The method comprises the following steps: obtaining the effective value of the output electrical parameter of each device in the parallel system; if it is determined that each device is not in a current sharing state according to the effective value of the output electrical parameter of each device, determining the conduction period of the output controllable switch of each device according to the effective value of the output electrical parameter of each device, and controlling the on-off of the output controllable switch of each device according to the conduction period of the output controllable switch of each device; wherein, at the same time, the output controllable switch of at least one device is in a conduction state. The application can realize current sharing between devices in a software mode, and in the process, the load will not be powered off. In addition, compared with the hardware current sharing mode, the hardware cost and the system size will not be increased.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of current sharing, in particular to a current sharing control method of a parallel system and the parallel system. BACKGROUND

[0002] The parallel system includes multiple devices. When the multiple devices are connected in parallel, if current sharing control is not performed on each device, the current sharing degree of each device is large, the loss is large, and even some devices may be overloaded.

[0003] At present, the current sharing control methods of the parallel system are divided into two types, namely hardware method and software method. If the hardware method is used for current sharing control, the hardware cost and system size are increased. When the software method is used for current sharing control, in order to realize current sharing between devices, the load may be powered off at a certain moment. SUMMARY

[0004] Embodiments of the present application provide a current sharing control method of a parallel system and the parallel system, so as to solve the problem that in order to realize current sharing between devices, the load may be powered off at a certain moment when the parallel system performs current sharing control.

[0005] In a first aspect, embodiments of the present application provide a current sharing control method of a parallel system, the parallel system including at least two devices connected in parallel; the current sharing control method of the parallel system including:

[0006] obtaining an effective value of an output electrical parameter of each device in the parallel system;

[0007] If it is determined that each device is not in a current sharing state according to the effective value of the output electrical parameter of each device, the on-off period of the output controllable switch of each device is determined according to the effective value of the output electrical parameter of each device, and the on-off of the output controllable switch of each device is controlled according to the on-off period of the output controllable switch of each device.

[0008] Among them, at the same moment, the output controllable switch of at least one device is in a conductive state.

[0009] In a possible implementation, the on-off period of the output controllable switch of each device is determined according to the effective value of the output electrical parameter of each device, and the on-off of the output controllable switch of each device is controlled according to the on-off period of the output controllable switch of each device, including:

[0010] For the device as the master, the on-off period of the output controllable switch of the device is determined as a full period, and the output controllable switch of the device is controlled to be conductive in the full period; the effective value of the output electrical parameter of the device as the master is the smallest.

[0011] For each device as a slave, a conduction angle of an output controllable switch of the device is determined according to an effective value of an output electrical parameter of the device, and the output controllable switch of the device is controlled according to the conduction angle of the output controllable switch of the device.

[0012] In a possible implementation, after controlling the output controllable switch of the device to be conductive for a full cycle, the current-sharing control method of the parallel system further includes:

[0013] An emergency exit frame of the device as the master is obtained; the emergency exit frame is used to indicate that the device as the master is about to exit, and instruct other devices in the parallel system to trigger an action of re-competition for the master.

[0014] In a possible implementation, after controlling the output controllable switch of the device according to the conduction angle of the output controllable switch of the device, the current-sharing control method of the parallel system further includes:

[0015] When a preset time length elapses, whether each device is in the current-sharing state is re-determined according to a current effective value of an output electrical parameter of each device;

[0016] If each device is still not in the current-sharing state, an action of re-competition for the master is triggered according to a current effective value of an output electrical parameter of each device.

[0017] In a possible implementation, when a new device is incorporated into the parallel system, the new device is taken as a slave, and the steps of determining a conduction angle of an output controllable switch of the device according to an effective value of an output electrical parameter of the device, and controlling the output controllable switch of the device according to the conduction angle of the output controllable switch of the device are performed.

[0018] In a possible implementation, controlling the output controllable switch of the device according to the conduction angle of the output controllable switch of the device includes:

[0019] A grid phase-locking angle is obtained in real time;

[0020] Whether a positive half cycle is reached is determined according to the grid phase-locking angle;

[0021] If it is determined that the positive half cycle is reached, the output controllable switch of the device is controlled according to the grid phase-locking angle and the conduction angle of the output controllable switch of the device;

[0022] If it is determined that the positive half cycle is not reached, the conduction angle of the output controllable switch of the device is increased by a preset number of degrees to obtain an updated conduction angle of the output controllable switch of the device, and the output controllable switch of the device is controlled according to the grid phase-locking angle and the updated conduction angle of the output controllable switch of the device; the preset number of degrees is a number of degrees corresponding to a half cycle.

[0023] In a possible implementation, if it is determined that the phase is in the positive half cycle, the on-off of the output controllable switch of the device is controlled according to the grid phase angle and the conduction angle of the output controllable switch of the device, including:

[0024] If it is determined that the phase is in the positive half cycle, when the grid phase angle is less than the conduction angle of the output controllable switch of the device, the output controllable switch of the device is controlled to keep in the off state; when the grid phase angle is greater than or equal to the conduction angle of the output controllable switch of the device, the output controllable switch of the device is controlled to keep in the on state until the current positive half cycle ends.

[0025] In a possible implementation, the conduction angle of the output controllable switch of the device is determined according to the effective value of the output electrical parameter of the device, including:

[0026] calculating the average effective value;

[0027] calculating the difference between the average effective value and the effective value of the output electrical parameter of the device;

[0028] inputting the difference into a preset PI controller to obtain the conduction angle of the output controllable switch of the device;

[0029] wherein the average effective value is the average of the effective values of the output electrical parameters of the devices.

[0030] In a possible implementation, the effective value of the output electrical parameter of each device is the effective value of the output electrical parameter of each device in the same switching cycle.

[0031] In a second aspect, an embodiment of the present application provides a parallel system, including a system-level controller, a plurality of devices connected in parallel, and a device-level controller corresponding to each device; the system-level controller is in communication connection with the device-level controllers, and the device-level controllers are in communication connection with each other.

[0032] The system-level controller or the device-level controller corresponding to the host device executes the current-sharing control method of the parallel system as described in the first aspect or any possible implementation of the first aspect.

[0033] The embodiment of the present application provides a current-sharing control method of a parallel system and the parallel system, the method determines the conduction period of the output controllable switch of each device according to the effective value of the output electrical parameter of each device when each device is not in the current-sharing state, controls the on-off of the output controllable switch of each device according to the conduction period of the output controllable switch of each device, and at least one output controllable switch of each device is in the on state at the same time, which can realize current sharing between devices in a software manner, and there is no situation of load power-off in the process; in addition, compared with the hardware current-sharing mode, the hardware cost and the system size are not increased. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort.

[0035] Figure 1 is a flowchart of the current sharing control method of the parallel system provided by the embodiments of the present application;

[0036] Figure 2 is a current diagram of the parallel system in the uncontrolled state provided by the embodiments of the present application;

[0037] Figure 3 is a current diagram of the parallel system in the current sharing control state provided by the embodiments of the present application;

[0038] Figure 4 is a structural diagram of the current sharing control device of the parallel system provided by the embodiments of the present application;

[0039] Figure 5 is a schematic diagram of the main controller provided by the embodiments of the present application. DETAILED DESCRIPTION

[0040] In the following description, specific details are set forth in order to provide a thorough understanding of the embodiments of the present application. However, persons skilled in the art will understand that the present application can be practiced without these specific details. In other instances, well-known systems, devices, circuits and methods have not been described in detail so as not to obscure the present application.

[0041] In order to make the objects, technical solutions and advantages of the present application clearer, the following will be described with reference to the accompanying drawings through specific embodiments.

[0042] Referring to Figure 1 , which shows the implementation flowchart of the current sharing control method of the parallel system provided by the embodiments of the present application. The parallel system includes at least two parallel devices; the current sharing control method of the parallel system includes:

[0043] In S101, the output electrical parameter effective value of each device in the parallel system is obtained.

[0044] The output electrical parameter effective value of the device can be the output current effective value or the output power effective value of the device, etc.

[0045] Each device has a corresponding sampling device at the output end to collect the corresponding output current, output voltage, etc., and calculate the output current effective value.

[0046] The parallel system can also include a system-level controller and a device-level controller corresponding to each device, each device being controlled by the corresponding device-level controller, and the sampling device of each device being connected to the corresponding device-level controller and sending the collected information to the corresponding device-level controller.

[0047] The system-level controller is in communication connection with the device-level controllers, and the device-level controllers are in communication connection with each other. The specific communication connection mode is not limited, such as CAN (Controller Area Network) bus communication connection, etc.

[0048] The execution subject of the current-sharing control method of the parallel system can be the system-level controller or one of the device-level controllers, such as the device corresponding to the device-level controller being the host competing out.

[0049] When the execution subject is the system-level controller, each device-level controller can send the output electrical parameter effective value of the corresponding device to the system-level controller. When the execution subject is one of the device-level controllers, the other device-level controllers can send the output electrical parameter effective value of the corresponding device to the device-level controller as the execution subject.

[0050] Among them, the device can be a device containing a power conversion module, such as a UPS (Uninterruptible Power Supply) or a charging pile, etc.

[0051] In S102, if it is determined that each device is not in the current-sharing state according to the output electrical parameter effective value of each device, the on-off period of the output controllable switch of each device is determined according to the output electrical parameter effective value of each device, and the on-off of the output controllable switch of each device is controlled according to the on-off period of the output controllable switch of each device; among them, at the same time, the output controllable switch of at least one device is in the on state.

[0052] In this embodiment, the average value of the output electrical parameter effective value of each device can be calculated to obtain the average effective value, and the absolute value of the difference between the output electrical parameter effective value of each device and the average effective value can be calculated; if the absolute value of the difference between the output electrical parameter effective value of each device and the average effective value is less than the preset electrical parameter difference, it is determined that each device is in the current-sharing state, otherwise, it is determined that each device is not in the current-sharing state. The preset electrical parameter difference can be set according to actual needs, which is a small value.

[0053] When it is determined that the devices are in the current-sharing state, the devices are controlled to work in the current state.

[0054] When it is determined that the devices are not in the current-sharing state, the on-off period of the output controllable switch of each device can be determined according to the effective value of the output electrical parameter of each device, and the on-off of the output controllable switch of each device can be controlled according to the on-off period of the output controllable switch of each device, but in the control process, it is necessary to ensure that at least one output controllable switch of the devices is in the on state at the same time, so that the on-off of the output controllable switch of each device is adjusted to gradually change the devices to the current-sharing state, and the load is ensured to be continuously powered during the current-sharing control process. The output controllable switch of each device is used to control whether the corresponding device has an output, and when it is in the on state, the corresponding device has an output, and when it is in the off state, the corresponding device does not output. The on-off period of the output controllable switch is less than or equal to the switching period of the output controllable switch.

[0055] Exemplarily, if the devices are UPSs, the current-sharing control method of the parallel system described above can be used to control the current sharing of the devices when the devices all work in the main path state, at this time, the output controllable switch of each device is the output SCR (Silicon Controlled Rectifier, Silicon Controlled Rectifier) of the main path of the corresponding UPS; the current-sharing control method of the parallel system described above can also be used to control the current sharing of the devices when the devices all work in the bypass state, at this time, the output controllable switch of each device is the output SCR of the bypass of the corresponding UPS; the current-sharing control method of the parallel system described above can also be used to control the current sharing of the devices when part of the devices work in the main path state and part of the devices work in the bypass state, at this time, the output controllable switch of the device working in the main path state is the output SCR of the main path of the corresponding UPS, and the output controllable switch of the device working in the bypass state is the output SCR of the bypass of the corresponding UPS.

[0056] Due to the zero-crossing turn-off characteristic of the SCR, the output ASR can be controlled by the IO.

[0057] In this embodiment, when the devices are not in the current-sharing state, the on-off period of the output controllable switch of each device is determined according to the effective value of the output electrical parameter of each device, and the on-off of the output controllable switch of each device is controlled according to the on-off period of the output controllable switch of each device, and at the same time, at least one output controllable switch of the devices is in the on state, which can realize active current sharing between devices in a software manner, and during the process, the load will not be powered off; in addition, compared with the hardware current sharing method, the hardware cost and system size are not increased.

[0058] In some possible implementation manners, before S101, the method can further include:

[0059] determining whether a current sharing instruction is received;

[0060] Correspondingly, S101 can include:

[0061] When the current sharing instruction is received, the output electrical parameter effective value of each device in the system is obtained.

[0062] In some embodiments, in S102, according to the output electrical parameter effective value of each device, the on period of the output controllable switch of each device is determined, and according to the on period of the output controllable switch of each device, the on-off of the output controllable switch of each device is controlled, including:

[0063] For the device as the master, the on period of the output controllable switch of the device is determined as the full period, and the output controllable switch of the device is controlled to be on in the full period; the output electrical parameter effective value of the device as the master is the smallest;

[0064] For each device as the slave, according to the output electrical parameter effective value of the device, the on angle of the output controllable switch of the device is determined, and according to the on angle of the output controllable switch of the device, the on-off of the output controllable switch of the device is controlled.

[0065] In this embodiment, the device with the smallest output electrical parameter effective value is taken as the master, and the output controllable switch of the device is controlled to be on in the full period, i.e. always on, so that at the same time, at least the device can supply power to the load, ensuring that the load is continuously powered, and by controlling the on angle of the output controllable switch of the device as the slave, the on period of the output controllable switch of the device as the slave is controlled, the current of the slave can be shared to the master, and finally current sharing is realized.

[0066] Among them, each device except the device as the master is taken as the slave.

[0067] For each device as the slave, according to the output electrical parameter effective value of the device, the on angle of the output controllable switch of the device is determined, and according to the on angle of the output controllable switch of the device, the on-off of the output controllable switch of the device is controlled, so as to achieve the purpose of controlling the on period of the output controllable switch of the device, and finally realize current sharing among devices.

[0068] In some possible implementation manners, when the execution subject is a system-level controller, the operation of competing for the master can be directly performed in the system-level controller, which selects a device with the minimum output parameter effective value as the master and other devices as slaves by acquiring the output parameter effective values of the devices; or the operation of competing for the master can be performed among the devices, and after the master is competed for, the system-level controller is informed. When the execution subject is a device-level controller corresponding to the master, the operation of competing for the master is performed among the devices, and after the master is competed for, the device-level controller corresponding to the master performs subsequent current-sharing control operations.

[0069] When the operation of competing for the master is performed among the devices, the device-level controller of each device can report the output electrical parameter effective value of the device in the form of a current-sharing information frame, for example, a current-sharing information frame can be sent at each zero-crossing point of each phase, and then the frame can be sent twice at two zero-crossing points in one period. After the sending, the current-sharing information frames of other devices are received, and after the receiving is completed, the master is determined.

[0070] In some possible implementation manners, the current-sharing control method of the parallel system provided in this embodiment can be executed in the device-level controller corresponding to each device. Exemplarily, each device-level controller can first compete for the master among the devices, the device-level controller corresponding to the device serving as the master controls the corresponding device to perform the operation corresponding to the master, that is, the output controllable switch of the device can be controlled to be conductive in a full cycle; and the device-level controller corresponding to the device serving as a slave controls the corresponding device to perform the operation corresponding to the slave, that is, the conduction angle of the output controllable switch of the device is determined according to the output electrical parameter effective value of the device, and the on-off of the output controllable switch of the device is controlled according to the conduction angle.

[0071] By controlling the output controllable switch of the master to be conductive in a full cycle, the embodiment can ensure that the load is continuously powered, and by determining the conduction angle of the output controllable switch of each slave and controlling the on-off of the corresponding output controllable switch according to the conduction angle, current sharing among the devices can be achieved.

[0072] In some embodiments, for the device serving as the master, after the output controllable switch of the device is controlled to be conductive in a full cycle, the current-sharing control method of the parallel system further includes:

[0073] An emergency exit frame of the device serving as the master is acquired; the emergency exit frame is used to indicate that the device serving as the master is about to exit, and instruct other devices in the parallel system to trigger the action of re-competition for the master.

[0074] When the device as the master is about to exit, for example, is about to stop working, or is about to be removed or replaced from the parallel system, so that it no longer belongs to the parallel system, it will report an emergency exit frame when it is about to exit. The emergency exit frame can instruct other devices (as slaves) in the parallel system to trigger the action of re-competition for the master, and after a new master is competed, jump to the step S101 for continuous execution. Before re-competition for the master, all devices are restored to the non-control state, that is, all devices are full-cycle on, and then the action of re-competition for the master is performed.

[0075] If the device about to exit is a slave, it does not affect the current sharing control of other devices.

[0076] In some embodiments, after the above S102, the current sharing control method of the parallel system further includes:

[0077] When the preset time period is reached, the current output electrical parameter effective value of each device is determined, and it is determined whether each device is in a current sharing state.

[0078] If each device is still not in the current sharing state, the current output electrical parameter effective value of each device is determined, and the action of re-competition for the master is triggered.

[0079] In this embodiment, after the parallel system is controlled by the above method, if each device is still not in the current sharing state after the preset time period, it indicates that the current sharing control has not been achieved among the devices, and the output electrical parameter effective value of each device has changed. The action of re-competition for the master is triggered according to the current output electrical parameter effective value of each device, and after a new master is competed, the above method is used for current sharing control again.

[0080] The preset time period can be set according to actual needs, and is not limited here.

[0081] In this embodiment, when the current sharing is not achieved for a long time, the current sharing scheme is adjusted again, and current sharing control is performed again, so as to finally achieve current sharing among the devices.

[0082] In some embodiments, when a new device is incorporated into the parallel system, the new device is used as a slave, and the steps of determining the conduction angle of the output controllable switch of the device according to the output electrical parameter effective value of the device, and controlling the on-off of the output controllable switch of the device according to the conduction angle of the output controllable switch of the device are performed.

[0083] When a new device is incorporated into the parallel system, the new device can be used as a slave, and corresponding current sharing control is performed. If the uneven current sharing situation exists after the preset time period, the action of re-competition for the master is triggered.

[0084] In some embodiments, the controlling the on-off of the output controllable switch of the device according to the conduction angle of the output controllable switch of the device includes:

[0085] acquiring the grid phase angle in real time;

[0086] determining whether the phase is in a positive half cycle according to the grid phase angle;

[0087] if it is determined that the phase is in the positive half cycle, controlling the on-off of the output controllable switch of the device according to the grid phase angle and the conduction angle of the output controllable switch of the device;

[0088] if it is determined that the phase is not in the positive half cycle, increasing the conduction angle of the output controllable switch of the device by a preset angle to obtain an updated conduction angle of the output controllable switch of the device, and controlling the on-off of the output controllable switch of the device according to the grid phase angle and the updated conduction angle of the output controllable switch of the device; the preset angle is an angle corresponding to a half cycle.

[0089] The grid synchronization system is synchronized with the grid and follows the phase of the grid frequency, so that the grid phase angle can be acquired, and whether the phase is in a positive half cycle can be determined according to the grid phase angle. The conduction angle of the output controllable switch of the slave device is an angle at which the output controllable switch is turned on when the phase is in the positive half cycle, and the range of the angle is between 0 and 180 degrees. Therefore, when the phase is not in the positive half cycle, i.e., when the phase is in a negative half cycle, the conduction angle needs to be increased by a preset angle to be a conduction angle corresponding to the negative half cycle. The preset angle is an angle corresponding to a half cycle, which is usually 180 degrees.

[0090] In some embodiments, if it is determined that the phase is in the positive half cycle, the controlling the on-off of the output controllable switch of the device according to the grid phase angle and the conduction angle of the output controllable switch of the device includes:

[0091] if it is determined that the phase is in the positive half cycle, controlling the output controllable switch of the device to remain in an off state when the grid phase angle is less than the conduction angle of the output controllable switch of the device, and controlling the output controllable switch of the device to remain in a on state when the grid phase angle is greater than or equal to the conduction angle of the output controllable switch of the device until the current positive half cycle ends.

[0092] In some embodiments, if it is determined that the phase is not in the positive half cycle, the controlling the on-off of the output controllable switch of the device according to the grid phase angle and the updated conduction angle of the output controllable switch of the device includes:

[0093] In the negative half cycle, when the grid phase angle is less than the updated conduction angle of the output controllable switch of the device, the output controllable switch of the device is controlled to keep off; when the grid phase angle is greater than or equal to the updated conduction angle of the output controllable switch of the device, the output controllable switch of the device is controlled to keep on until the end of the current negative half cycle.

[0094] In some embodiments, the determination of the conduction angle of the output controllable switch of the device according to the effective value of the output electrical parameter of the device comprises:

[0095] calculating the average effective value;

[0096] calculating the difference between the average effective value and the effective value of the output electrical parameter of the device;

[0097] inputting the difference into a preset PI controller to obtain the conduction angle of the output controllable switch of the device;

[0098] The average effective value is the average value of the effective values of the output electrical parameters of the devices.

[0099] The parameters of the preset PI controller are determined in advance, and when the difference between the average effective value and the effective value of the output electrical parameter of the device is input, the conduction angle of the output controllable switch of the device can be obtained.

[0100] In some possible implementations, the conduction angle of the output controllable switch of the device can be limited, and the output controllable switch of the device is controlled using the limited conduction angle of the output controllable switch.

[0101] Exemplarily, taking the device as a UPS and the output controllable switch as an SCR as an example, assuming that the parallel system includes two parallel UPSs, namely UPS1 and UPS2, the output controllable switch corresponding to UPS1 is SCR1, and the output controllable switch corresponding to UPS2 is SCR2. When both of the two UPSs are uncontrolled, that is, both are full-period on, the currents of the two are as shown in Figure 2 When UPS2 is the master and SCR2 is full-period on, and UPS1 is the slave and the conduction angle of SCR2 is α, the currents of the two are as shown in Figure 3 .

[0102] In some embodiments, the effective value of the output electrical parameter of each device is the effective value of the output electrical parameter of each device in the same switching period.

[0103] By collecting the effective values of the output electrical parameters of the devices in the same switching period, the uneven current of the devices caused by the switching period factor can be excluded.

[0104] It should be noted that the above method can be used for current sharing control of the A, B and C phases of the device, and the host obtained by competition can be the same device or different devices, and the current sharing control between the phases is independent.

[0105] It should be understood that the size of the serial number of each step in the above embodiment does not mean the order of execution, and the execution order of each process should be determined according to its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the application.

[0106] The following is a device embodiment of the application, and for details not described in detail, reference can be made to the corresponding method embodiments described above.

[0107] Figure 4 A structure diagram of the current sharing control device of the parallel system provided by the embodiment of the application is shown, only the parts related to the embodiment of the application are shown for convenience of description, and the details are as follows:

[0108] The parallel system includes at least two devices connected in parallel; as Figure 4 The current sharing control device 30 of the parallel system can include an acquisition module 31 and a current sharing control module 32.

[0109] The acquisition module 31 is configured to acquire the effective value of the output electrical parameter of each device in the parallel system.

[0110] The current sharing control module 32 is configured to determine the on period of the output controllable switch of each device according to the effective value of the output electrical parameter of each device if it is determined that each device is not in the current sharing state according to the effective value of the output electrical parameter of each device, and control the on-off of the output controllable switch of each device according to the on period of the output controllable switch of each device.

[0111] At the same time, the output controllable switch of at least one device is in the on state.

[0112] In a possible implementation, in the current sharing control module 32, the on period of the output controllable switch of each device is determined according to the effective value of the output electrical parameter of each device, and the on-off of the output controllable switch of each device is controlled according to the on period of the output controllable switch of each device, including:

[0113] For the device as the host, the on period of the output controllable switch of the device is determined as the full period, and the output controllable switch of the device is controlled to be on in the full period; the effective value of the output electrical parameter of the device as the host is the smallest.

[0114] For each device as a slave, according to the effective value of the output electrical parameter of the device, the conduction angle of the output controllable switch of the device is determined, and according to the conduction angle of the output controllable switch of the device, the on-off of the output controllable switch of the device is controlled.

[0115] In a possible implementation, in the current sharing control module 32, after controlling the output controllable switch of the device to be full-cycle on, the current sharing control method of the parallel system further includes:

[0116] An emergency exit frame of the device as the master is acquired; the emergency exit frame is used to indicate that the device as the master is about to exit, and instruct other devices in the parallel system to trigger the action of re-competition for the master.

[0117] In a possible implementation, in the current sharing control module 32, after controlling the on-off of the output controllable switch of the device according to the conduction angle of the output controllable switch of the device, the current sharing control method of the parallel system further includes:

[0118] When a preset time length is elapsed, whether each device is in the current sharing state is re-determined according to the current effective value of the output electrical parameter of each device;

[0119] If each device is still not in the current sharing state, the action of re-competition for the master is triggered according to the current effective value of the output electrical parameter of each device.

[0120] In a possible implementation, when a new device is incorporated into the parallel system, the new device is taken as a slave, and the steps of determining the conduction angle of the output controllable switch of the device according to the effective value of the output electrical parameter of the device, and controlling the on-off of the output controllable switch of the device according to the conduction angle of the output controllable switch of the device are performed.

[0121] In a possible implementation, in the current sharing control module 32, controlling the on-off of the output controllable switch of the device according to the conduction angle of the output controllable switch of the device includes:

[0122] The grid phase locking angle is acquired in real time;

[0123] Whether the phase is in a positive half cycle is determined according to the grid phase locking angle;

[0124] If it is determined that the phase is in the positive half cycle, the on-off of the output controllable switch of the device is controlled according to the grid phase locking angle and the conduction angle of the output controllable switch of the device;

[0125] If it is determined that the phase is not in the positive half cycle, the conduction angle of the output controllable switch of the device is increased by a preset degree to obtain the updated conduction angle of the output controllable switch of the device, and the output controllable switch of the device is controlled to be on and off according to the grid phase-locked angle and the updated conduction angle of the output controllable switch of the device; the preset degree is the degree corresponding to half a cycle.

[0126] In one possible implementation, in the current sharing control module 32, if it is determined that the phase is in the positive half cycle, the output controllable switch of the device is controlled to be on and off according to the grid phase-locked angle and the conduction angle of the output controllable switch of the device, including:

[0127] If it is determined that the phase is in the positive half cycle, then when the grid phase-locked angle is less than the conduction angle of the output controllable switch of the device, the output controllable switch of the device is controlled to remain in the off state; when the grid phase-locked angle is greater than or equal to the conduction angle of the output controllable switch of the device, the output controllable switch of the device is controlled to remain in the on state until the end of the current positive half cycle of the phase.

[0128] In one possible implementation, in the current sharing control module 32, determining the conduction angle of the output controllable switch of the device according to the effective value of the output electrical parameter of the device includes:

[0129] Calculate the average effective value;

[0130] Calculate the difference between the average effective value and the effective value of the output electrical parameter of the device;

[0131] The difference is input into a preset PI controller to obtain the conduction angle of the output controllable switch of the device;

[0132] The average effective value is the average of the effective values ​​of the output electrical parameters of each device.

[0133] In a possible implementation, the effective value of the output electrical parameter of each device is the effective value of the output electrical parameter of each device in the same switching cycle.

[0134] Figure 5 Schematic diagram of the main controller provided by the embodiment of the present invention. Figure 5 As shown, the main controller 4 of this embodiment includes: a processor 40 and a memory 41. The memory 41 is used to store a computer program 42, and the processor 40 is used to call and run the computer program 42 stored in the memory 41 to perform the steps in the above-mentioned embodiments of the current sharing control method for each parallel system, such as Figure 1 Alternatively, the processor 40 is used to call and run the computer program 42 stored in the memory 41 to implement the functions of each module / unit in the above-mentioned device embodiments, such as Figure 4 Functions of the modules / units 31 to 32 shown.

[0135] For example, the computer program 42 can be divided into one or more modules / units stored in the memory 41 and executed by the processor 40 to complete the present application. The one or more modules / units can be a series of computer program instruction segments capable of completing a specific function, which are used to describe the execution process of the computer program 42 in the host controller 4. For example, the computer program 42 can be divided into the modules / units 31 to 32 shown. Figure 4

[0136] The host controller 4 can be a system-level controller of a parallel system or a device-level controller corresponding to a device as a host, etc. The host controller 4 can include, but is not limited to, the processor 40, the memory 41. Those skilled in the art can understand that the host controller 4 can include more or fewer components than those shown, or combine certain components, or include different components, for example, the host controller can also include an input / output device, a network access device, a bus, etc. Figure 5 The host controller 4 shown is only an example and does not constitute a limitation on the host controller 4, and can include more or fewer components than those shown, or combine certain components, or include different components, for example, the host controller can also include an input / output device, a network access device, a bus, etc.

[0137] The processor 40 can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic components, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0138] The memory 41 can be an internal storage unit of the host controller 4, for example, a hard disk or a memory of the host controller 4. The memory 41 can also be an external storage device of the host controller 4, for example, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. Further, the memory 41 can include both an internal storage unit and an external storage device of the host controller 4. The memory 41 is used to store the computer program and other programs and data required by the host controller. The memory 41 can also be used to temporarily store data that has been output or will be output.​

[0139] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the above-mentioned division of each functional unit and module is exemplified, and in actual application, the above-mentioned functions can be completed by different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit, and the integrated unit can be realized in the form of hardware or software. In addition, the specific name of each functional unit and module is only for easy distinction, and does not limit the protection scope of the application. The specific working process of the unit and module in the system can refer to the corresponding process in the foregoing method embodiments, which will not be described here.

[0140] Corresponding to the above-mentioned current sharing control method of the parallel system, the embodiment of the application further provides a parallel system, comprising a system-level controller, a plurality of devices connected in parallel, and a device-level controller corresponding to each device; the system-level controller is in communication connection with the device-level controllers, and the device-level controllers are in communication connection with each other.

[0141] The system-level controller or the device-level controller corresponding to the device as the host executes any one of the current sharing control methods of the parallel system described above. For details, please refer to the description of the current sharing control method of the parallel system described above, which will not be described here.

[0142] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described or recorded in detail in a certain embodiment can be referred to the related description of other embodiments.

[0143] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized in electronic hardware or a combination of computer software and electronic hardware. Whether the functions are executed in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0144] In the embodiments of the present application, it should be understood that the disclosed apparatuses and master controllers and methods can be implemented in other manners. For example, the described apparatuses and master controller embodiments are merely schematic. The division of the modules or units is merely logical function division. There can be another division manner in actual implementation. For example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections can be indirect couplings or communication connections through some interfaces, devices or units, and can be in electrical, mechanical or other forms.

[0145] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, that is, can be located in one place, or can be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the embodiments.

[0146] In addition, each functional unit in the various embodiments of the present application can be integrated into a processing unit, or each unit can be a physically independent unit, or two or more units can be integrated into a unit. The integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0147] The integrated module / unit, if implemented in the form of a software functional unit and sold or used as an independent product, can be stored in a computer readable storage medium. Based on this understanding, all or part of the flow of the above-mentioned embodiment methods can also be completed by a computer program instructing related hardware, and the computer program can be stored in a computer readable storage medium. When the processor executes the computer program, the steps of each flow control method embodiment described above can be implemented. The computer program includes computer program code, which can be in the form of source code, object code, executable file or some intermediate form. The computer readable medium can include any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium, etc.

[0148] The above-described embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part 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 the present application, and should be included in the protection scope of the present application.

Claims

1. A current sharing control method of a parallel system, characterized by, The parallel system comprises at least two parallel devices; and a current sharing control method of the parallel system comprises: acquiring effective values of output electrical parameters of each device in the parallel system; if it is determined that each device is not in a current sharing state according to the effective values of the output electrical parameters of each device, determining a conduction period of an output controllable switch of each device according to the effective values of the output electrical parameters of each device, and controlling on-off of the output controllable switch of each device according to the conduction period of the output controllable switch of each device; wherein at the same time, the output controllable switch of at least one device is in a conduction state; the determining of the conduction period of the output controllable switch of each device according to the effective values of the output electrical parameters of each device, and the controlling of the on-off of the output controllable switch of each device according to the conduction period of the output controllable switch of each device, comprises: for a device as a master, determining that the conduction period of the output controllable switch of the device is a full period, and controlling the output controllable switch of the device to be in a conduction state in the full period; the effective value of the output electrical parameter of the device as the master is the smallest; for each device as a slave, determining a conduction angle of the output controllable switch of the device according to the effective value of the output electrical parameter of the device, and controlling the on-off of the output controllable switch of the device according to the conduction angle of the output controllable switch of the device.

2. The current sharing control method of a parallel system according to claim 1, wherein after the controlling of the output controllable switch of the device to be in the conduction state in the full period, the current sharing control method of the parallel system further comprises: acquiring an emergency exit frame of the device as the master; the emergency exit frame is used to indicate that the device as the master is about to exit, and to indicate that other devices in the parallel system trigger an action of re-competition for the master.

3. The current sharing control method of a parallel system according to claim 1, wherein after the controlling of the on-off of the output controllable switch of the device according to the conduction angle of the output controllable switch of the device, the current sharing control method of the parallel system further comprises: after a preset time period elapses, re-determining whether each device is in a current sharing state according to current effective values of output electrical parameters of each device; if each device is still not in the current sharing state, triggering the action of re-competition for the master according to the current effective values of the output electrical parameters of each device.

4. The current sharing control method of a parallel system according to claim 1, wherein when a new device is incorporated into the parallel system, the new device is taken as a slave, and the steps of determining a conduction angle of an output controllable switch of the device according to the effective value of the output electrical parameter of the device, and controlling the on-off of the output controllable switch of the device according to the conduction angle of the output controllable switch of the device are performed.

5. The current sharing control method of a parallel system according to any one of claims 1 to 4, characterized in that, the controlling of the on-off of the output controllable switch of the device according to the conduction angle of the output controllable switch of the device, comprises: acquiring a grid phase locking angle in real time; determining whether a positive half cycle is in a phase according to the grid phase locking angle; if it is determined that the positive half cycle is in the phase, controlling the on-off of the output controllable switch of the device according to the grid phase locking angle and the conduction angle of the output controllable switch of the device. If it is determined that the phase is not in the positive half cycle, the conduction angle of the output controllable switch of the device is increased by a preset number of degrees, an updated conduction angle of the output controllable switch of the device is obtained, and the on-off of the output controllable switch of the device is controlled according to the grid phase locking angle and the updated conduction angle of the output controllable switch of the device; the preset number of degrees is the number of degrees corresponding to a half cycle.

6. The current sharing control method of a parallel system according to claim 5, wherein If it is determined that the phase is in the positive half cycle, the on-off of the output controllable switch of the device is controlled according to the grid phase locking angle and the conduction angle of the output controllable switch of the device, including: If it is determined that the phase is in the positive half cycle, when the grid phase locking angle is less than the conduction angle of the output controllable switch of the device, the output controllable switch of the device is controlled to remain in the off state; when the grid phase locking angle is greater than or equal to the conduction angle of the output controllable switch of the device, the output controllable switch of the device is controlled to remain in the on state until the current positive half cycle ends.

7. The current sharing control method of a parallel system according to any one of claims 1 to 4, characterized in that, The conduction angle of the output controllable switch of the device is determined according to the effective value of the output electrical parameter of the device, including: calculating an average effective value; calculating the difference between the average effective value and the effective value of the output electrical parameter of the device; inputting the difference into a preset PI controller to obtain the conduction angle of the output controllable switch of the device; wherein the average effective value is the average of the effective values of the output electrical parameters of the devices.

8. The current sharing control method of a parallel system according to any one of claims 1 to 4, characterized in that, The effective value of the output electrical parameter of each device is the effective value of the output electrical parameter of each device in the same switching cycle.

9. A parallel system, characterized by The system includes a system-level controller, a plurality of devices connected in parallel, and a device-level controller corresponding to each device; the system-level controller is in communication connection with the device-level controllers, and the device-level controllers are in communication connection with each other; The system-level controller or the device-level controller corresponding to the host device executes the current sharing control method of the parallel system as claimed in any one of claims 1 to 8.

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