Power supply equipment, three-phase power supply system and control method

Abstract

This application provides a power supply device, a three-phase power supply system, and a control method, comprising N modules, where N is a positive integer greater than or equal to 2. Each module includes: a transformer, including a primary winding and a first secondary winding; and a first switching unit connected to the first secondary winding of the transformer. The primary windings of the transformers of the N modules are connected in series. The first switching unit operates in one of the following modes: bypass mode, open circuit mode, and modulation mode. The output of each module is controlled by the first switching unit, so that the power supply device can provide voltages of different amplitudes according to power demand. Furthermore, through modular design, there is no need to use large and heavy transformers such as centralized power frequency transformers or multi-winding transformers, which facilitates the transportation and maintenance of the power supply device.

Description

Technical Field

[0001] This application relates to the field of power supply technology, and in particular to a power supply device, a three-phase power supply system and a control method. Background Technology

[0002] Isolation rectifier systems include isolation rectifier systems based on centralized power frequency transformers and isolation rectifier systems based on multi-winding transformers.

[0003] Figure 1 This is a schematic diagram of a medium-voltage isolation AC / DC converter system based on a centralized power frequency transformer, as shown below. Figure 1 As shown, the AC / DC converter system includes a centralized power frequency transformer 101, multiple filters 102, and multiple modular rectifiers 103. Each modular rectifier 103 is connected to the centralized power frequency transformer 101 through a filter 102. The 10kV medium voltage is stepped down to a low voltage of 380V through the centralized power frequency transformer 101. Multiple 380V low voltages are filtered by the filters 102 and then input to the multiple modular rectifiers 103, outputting DC. By installing a filter 102 at the front end of each modular rectifier 103, multiple harmonics of the AC / DC converter system can be filtered out.

[0004] Figure 2 This is a schematic diagram of an isolation rectifier system based on a multi-winding transformer, as shown below. Figure 2 As shown, the isolated rectifier system includes a phase-shifting transformer 201, a modular rectifier 202, and a modular converter unit 203. Each secondary winding of the phase-shifting transformer 201 is connected to one modular rectifier 202, and each modular rectifier 202 is connected to one modular converter unit 203. This scheme is suitable for unidirectional rectifier systems, meaning power flows only from the grid to the load. Compared to... Figure 1 The proposed solution Figure 2 The proposed solution is low-cost and highly efficient.

[0005] However, for high-power applications, the weight of phase-shifting transformers is extremely large, making transportation difficult. This is especially true for applications such as data centers, where users need to install isolation rectifier systems in office buildings. The bulky phase-shifting transformer cannot be supported by elevators, requiring users to dismantle walls and hire cranes for installation, making construction extremely inconvenient. Furthermore, when the phase-shifting transformer windings are damaged, the entire unit must be replaced, making maintenance difficult. Summary of the Invention

[0006] This application provides a power supply device, a three-phase power supply system, and a control method, aiming to provide a modular power supply solution to facilitate the installation, maintenance, and other operations of the power supply system.

[0007] In a first aspect, an embodiment of the present application provides a power supply device, including:

[0008] N modules, where N is a positive integer greater than or equal to 2, and each module includes:

[0009] A transformer, including a primary winding and a first secondary winding; and

[0010] A first switching unit, connected to the first secondary winding of the transformer,

[0011] wherein the primary windings of the transformers of the N modules are connected in series, and the first switching unit operates in one of a bypass mode, an open-circuit mode, and a modulation mode.

[0012] In an embodiment, each module further includes:

[0013] A rectification unit, having an AC side and a DC side, and the AC side of the rectification unit is connected to the first secondary winding of the transformer.

[0014] In an embodiment, m1 modules operate in the bypass mode, 0 ≤ m1 ≤ M1; m2 modules operate in the uncontrolled rectification mode, 0 ≤ m2 ≤ M2; m3 modules operate in the modulation mode and can achieve power factor correction, 0 < m3; where m1 + m2 + m3 = N, M1 is the maximum number of modules that can be bypassed, and M2 is the maximum number of modules that can operate in the uncontrolled rectification mode.

[0015] In an embodiment, the m3 modules operating in the modulation mode adopt a carrier phase-shifted modulation method.

[0016] In an embodiment, the carrier phases of the m3 modules operating in the modulation mode differ by 2π / m3 in sequence. [[ID=2\9]]

[0017] In an embodiment, the primary windings of the transformers of the N modules are connected in series to a power grid.

[0018] In an embodiment, M1 is determined by the ratio of the voltage of the power grid to the voltage that the primary winding of the transformer of a single module can withstand, M2 is determined by the degree of current distortion allowed by the power grid, and M2 does not exceed N / 2.

[0019] In an embodiment, the m3 modules operating in the modulation mode all adopt current closed-loop and voltage feed-forward control, where the feed-forward voltage V _ ff The calculation formula of is:

[0020]

[0021] where V _ gA is the voltage of the power grid, i _ g is the current flowing through the power grid, sign is the sign function, and V _ dchThis represents the DC-side voltage of the rectifier unit of the h-th module in uncontrolled rectification mode.

[0022] In one embodiment, the DC sides of the rectifier units of N modules are connected in series or in parallel.

[0023] In one embodiment, the rectifier unit is a full-bridge controlled rectifier circuit, a full-bridge uncontrolled rectifier circuit, a half-bridge controlled rectifier circuit, or a half-bridge uncontrolled rectifier circuit.

[0024] In one embodiment, if the rectifier unit is a full-bridge controllable rectifier circuit, when the first switching unit of a certain module is in modulation mode, if the first switching unit of the module receives a turn-on signal, the rectifier unit of the module will operate in uncontrolled rectification mode; if the first switching unit of the module receives a turn-off signal, the rectifier unit of the module will operate in synchronous rectification mode.

[0025] In one embodiment, the transformer of each module further includes a second secondary winding, and the second secondary windings of the transformers of N modules are connected in series to form an AC power supply port.

[0026] In one embodiment, the transformer of each module further includes a third secondary winding, and each module further includes a second switching unit, with the third secondary winding and the second switching unit connected within the same module.

[0027] Secondly, one embodiment of this application provides a three-phase power supply system, including:

[0028] The three aforementioned power supply devices are connected to the three phases of a three-phase power supply via a Y-connection or a delta connection.

[0029] In one embodiment, a module is taken from each of the three power supply devices to form a three-phase module.

[0030] Thirdly, one embodiment of this application provides a control method for a power supply device.

[0031] Provide N modules, where N is a positive integer greater than or equal to 2. Each module includes:

[0032] A transformer, comprising a primary winding and a first secondary winding; and

[0033] The first switching unit is connected to the first secondary winding of the transformer.

[0034] In this configuration, the primary windings of the transformers of N modules are connected in series; and

[0035] The first switching unit is controlled to operate in one of the following modes: bypass mode, open-circuit mode, and modulation mode.

[0036] In one embodiment, each module further includes:

[0037] The rectifier unit has an AC side and a DC side, and the AC side of the rectifier unit is connected to the first secondary winding of the transformer.

[0038] In one embodiment, it includes:

[0039] Control m1 modules to operate in bypass mode, where 0 ≤ m1 ≤ M1;

[0040] Control m2 modules to operate in uncontrolled rectification mode, where 0 ≤ m2 ≤ M2; and

[0041] Controlling m3 modules to operate in modulation mode enables power factor correction, where 0 ≤ m3.

[0042] Where m1+m2+m3=N, M1 is the maximum number of modules that can be bypassed, and M2 is the maximum number of modules that can be opened.

[0043] In one embodiment, if the rectifier unit is an uncontrolled rectifier circuit, the control method includes:

[0044] In N modules, for the k-th module, after the start of its control cycle, check whether the k-th module itself has a fault;

[0045] If there is no fault, the kth module will enter modulation mode;

[0046] If there is a fault and the fault type is an open circuit fault of the first switching unit, and the number of modules in the N modules that are already in uncontrolled rectification mode is less than M2, then the kth module is put into uncontrolled rectification mode; otherwise, the system is shut down.

[0047] If there is a fault and the fault type is not an open circuit fault of the first switch unit, and the number of modules in the N modules that are already in bypass mode is less than M1, then the kth module is put into bypass mode; otherwise, the system is shut down.

[0048] In one embodiment, if the rectifier unit is a controllable rectifier circuit, the control method includes:

[0049] In N modules, for the k-th module, after the start of its control cycle, check whether the k-th module itself has a fault;

[0050] If there is no fault, the kth module will enter modulation mode;

[0051] If there is a fault and the fault type is an open circuit fault of the first switching unit, the rectifier unit of the kth module is used for modulation to make the kth module enter the modulation mode.

[0052] If there is a fault and the fault type is not an open circuit fault of the first switch unit, and the number of modules in the N modules that are already in bypass mode is less than M1, then the kth module is put into bypass mode; otherwise, the system is shut down.

[0053] In one embodiment, carrier phase-shift modulation is used to control m3 modules operating in modulation mode.

[0054] In one embodiment, the carrier phases of the m3 modules operating in modulation mode are successively differed by 2π / m3.

[0055] In one embodiment, the primary windings of N transformer modules are connected in series to a power grid. The m3 modules operating in modulation mode all employ current closed-loop and voltage feedforward control, with a feedforward voltage V. ff The calculation formula is:

[0056]

[0057] Among them, V gA Let i be the voltage of the power grid. g Let V be the current flowing through the power grid, sign be the sign function, and V be the current. dch This represents the DC-side voltage of the rectifier unit of the h-th module in uncontrolled rectification mode.

[0058] In one embodiment, if the rectifier unit is a full-bridge controllable rectifier circuit, when the first switching unit of a certain module is in modulation mode, if the first switching unit of the module receives a turn-on signal, the rectifier unit of the module will operate in uncontrolled rectification mode; if the first switching unit of the module receives a turn-off signal, the rectifier unit of the module will operate in synchronous rectification mode.

[0059] This application provides a power supply device, a three-phase power supply system, and a control method. The power supply device includes N modules, and each module is equipped with a transformer and a first switching unit. The output of each module is controlled by the first switching unit so that the power supply device can provide voltages of different amplitudes according to power demand. Moreover, through modular design, there is no need to use large-volume and heavy transformers such as centralized power frequency transformers or multi-winding transformers, which facilitates the transportation and maintenance of the power supply device. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of a medium-voltage isolation AC / DC converter system based on a centralized power frequency transformer.

[0061] Figure 2 This is a schematic diagram of an isolation rectifier system based on a multi-winding transformer.

[0062] Figure 3This is a schematic diagram of a first structure of a power supply device provided in an embodiment of this application;

[0063] Figure 4 This is a schematic diagram of a second structure of a power supply device provided in an embodiment of this application;

[0064] Figure 5 This is a schematic diagram of a third structure of a power supply device provided in an embodiment of this application;

[0065] Figure 6 This is a schematic diagram of a fourth structure of a power supply device provided in an embodiment of this application;

[0066] Figure 7 A control principle diagram of the first switching unit in modulation mode provided in an embodiment of this application;

[0067] Figure 8 This is a fifth structural schematic diagram of a power supply device provided in an embodiment of this application;

[0068] Figure 9 This is a sixth structural schematic diagram of a power supply device provided in an embodiment of this application;

[0069] Figure 10 This is a seventh structural schematic diagram of a power supply device provided in an embodiment of this application;

[0070] Figure 11 A schematic diagram of a three-phase power supply system provided in one embodiment of this application;

[0071] Figure 12 A flowchart illustrating a control method for a power supply device provided in one embodiment of this application;

[0072] Figure 13 A flowchart illustrating another control method for a power supply device provided in an embodiment of this application;

[0073] Figure 14 A flowchart illustrating another control method for a power supply device provided in an embodiment of this application;

[0074] Figure 15 A flowchart of another control method for a power supply device provided in an embodiment of this application. Detailed Implementation

[0075] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0076] like Figure 3 This is a schematic diagram of the structure of a power supply device provided in an embodiment of this application, as shown below. Figure 3 As shown, the power supply device includes N modules 10, where N is a positive integer greater than or equal to 2. Each module 10 includes a transformer 11 and a first switching unit 12. The transformer 11 includes a primary winding 111 and a first secondary winding 112. Within each module 10, the first switching unit 12 and the first secondary winding 112 of the transformer 11 are connected. The primary windings 111 of the transformers 11 in the N modules 10 are connected in series, and the primary windings 111 of the transformers 11 in the N modules 10 are connected in series to a power grid V. gA .

[0077] The N modules 10 are labeled as Module 1, Module 2, ..., Module N. Within each module 10, the connection between the first switching unit 12 and the first secondary winding 112 of the transformer 11 means that the first switching unit 12 of the first module is connected to the first secondary winding 112 of the transformer 11 of the first module, the first switching unit 12 of the second module is connected to the first secondary winding 112 of the transformer 11 of the second module, and so on, until the first switching unit 12 of the Nth module is connected to the first secondary winding 112 of the transformer 11 of the Nth module.

[0078] The series connection of the primary windings 111 of N modules 10 transformers 11 means that the second end of the primary winding 111 of the first module transformer 11 is connected to the first end of the primary winding 111 of the second module transformer 11, the second end of the primary winding 111 of the second module transformer 11 is connected to the first end of the primary winding 111 of the third module transformer 11, and so on, until the second end of the primary winding 111 of the (N-1)th module transformer 11 is connected to the first end of the primary winding 111 of the Nth module transformer 11. The first end of the primary winding 111 of the first module transformer 11 and the second end of the primary winding 111 of the Nth module transformer 11 are connected to the power grid.

[0079] The first switching unit 12 operates in one of the following modes: bypass mode, open-circuit mode, and modulation mode. Operating in bypass mode means that the first switching unit 12 is on for an extended period, preventing the corresponding module from operating. Operating in open-circuit mode means that the first switching unit 12 is off. Operating in modulation mode means that the first switching unit 12 is turned on and off at a certain frequency.

[0080] By switching the operating mode of the first switching unit 12, the output of each module 10 can be controlled, as well as the magnitude of the output voltage, thereby controlling the output of the power supply device.

[0081] In the above technical solution, the power supply device includes N modules 10, and each module 10 is equipped with a transformer 11 and a first switching unit 12. The output of each module 10 is controlled by the first switching unit 12 so that the power supply device can provide voltages of different amplitudes according to power demand. Moreover, through modular design, there is no need to use large-volume and heavy transformers 11 such as centralized power frequency transformers 11 or multi-winding transformers 11, which facilitates the transportation and maintenance of the power supply device.

[0082] In one embodiment, the first switching unit 12 includes a first switch T1 and a second switch T2. The second end of the first switch T1 is connected to the second end of the second switch T2, the first end of the first switch T1 is connected to one end of the first secondary winding 112, and the first end of the second switch T2 is connected to the other end of the first secondary winding 112. The first switch T1 and the second switch T2 can be IGBTs with anti-parallel diodes or MOSFETs.

[0083] When the first switch T1 and the second switch T2 are off, the first switching unit 12 operates in open-circuit mode. When the first switch T1 and the second switch T2 are turned on at a certain frequency and with a varying duty cycle, the first switching unit 12 operates in modulation mode. When the first switch T1 and the second switch T2 are turned on for an extended period of time, the first switching unit 12 operates in bypass mode.

[0084] In one embodiment, reference continues Figure 3 Each module 10 also includes a rectifier unit 13, which has an AC side and a DC side. The AC side of the rectifier unit 13 is connected to the first secondary winding 112 of the transformer 11.

[0085] The rectifier unit 13 is a full-bridge uncontrolled rectifier circuit, which includes a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, and a first capacitor C1. The anode of the first diode D1 is connected to the cathode of the second diode D2, and the anode of the third diode D3 is connected to the cathode of the fourth diode D4. The first terminal of the first capacitor C1 is connected to the cathode of the first diode D1, and the second terminal of the first capacitor C1 is connected to the anode of the second diode D2. The anode of the first diode D1 is connected to one end of the first secondary winding 112, and the anode of the third diode D3 is connected to the other end of the first secondary winding 112. The cathode of the first diode D1 is connected to the cathode of the third diode D3, serving as one output terminal of module 10. The anode of the second diode D2 is connected to the anode of the fourth diode D4, serving as the other output terminal of module 10.

[0086] Among them, reference Figure 4The rectifier unit 13 is a half-bridge uncontrolled rectifier circuit, which includes a fifth diode D5, a sixth diode D6, a third capacitor C3, and a fourth capacitor C4. The anode of the fifth diode D5 is connected to the cathode of the sixth diode D6, and the second terminal of the third capacitor C3 is connected to the first terminal of the fourth capacitor C4. The anode of the fifth diode D5 is connected to one end of the first secondary winding 112, and the first terminal of the fourth capacitor C4 is connected to the other end of the first secondary winding 112. The cathode of the fifth diode D5, after being connected to the first terminal of the third capacitor C3, serves as one output terminal of module 10, and the anode of the sixth diode D6, after being connected to the second terminal of the fourth capacitor C4, serves as the other output terminal of module 10.

[0087] When the rectifier unit 13 is a full-bridge uncontrolled rectifier circuit or a half-bridge uncontrolled rectifier circuit, when the first switching unit 12 of a certain module 10 is in open-circuit mode, the module 10 is in uncontrolled rectification mode. When the first switching unit 12 of a certain module 10 is in bypass mode, the module 10 is in bypass mode. When the first switching unit 12 of a certain module 10 is in modulation mode, the module 10 is in modulation mode.

[0088] Among them, reference Figure 5 The rectifier unit 13 is a full-bridge controllable rectifier circuit, which includes a first rectifier switch M1, a second rectifier switch M2, a third rectifier switch M3, and a fourth rectifier switch M4. The second terminal of the first rectifier switch M1 is connected to the first terminal of the second rectifier switch M2, and the second terminal of the third rectifier switch M3 is connected to the first terminal of the fourth rectifier switch M4. The first terminal of the second capacitor C2 is connected to the first terminal of the first rectifier switch M1, and the second terminal of the second capacitor C2 is connected to the second terminal of the second rectifier switch M2. The second terminal of the first rectifier switch M1 is connected to one end of the first secondary winding 112, and the second terminal of the third rectifier switch M3 is connected to the other end of the first secondary winding 112. The connection between the first terminal of the first rectifier switch M1 and the first terminal of the third rectifier switch M3 serves as one output terminal of module 10, and the connection between the second terminal of the second rectifier switch M2 and the second terminal of the fourth rectifier switch M4 serves as the other output terminal of module 10. The rectifier switches can be IGBTs or MOSFETs.

[0089] Among them, reference Figure 6The rectifier unit 13 is a half-bridge controlled rectifier circuit, which includes a fifth rectifier switch M5, a sixth rectifier switch M6, a seventh capacitor C7, and an eighth capacitor C8. The second terminal of the fifth rectifier switch M5 is connected to the first terminal of the sixth rectifier switch M6, and the second terminal of the seventh capacitor C7 is connected to the first terminal of the eighth capacitor C8. The second terminal of the fifth rectifier switch M5 is connected to one end of the first secondary winding 112, and the first terminal of the eighth capacitor C8 is connected to the other end of the first secondary winding 112. The connection between the first terminal of the fifth rectifier switch M5 and the first terminal of the seventh capacitor C7 serves as one output terminal of module 10, and the connection between the second terminal of the sixth rectifier switch M6 and the second terminal of the eighth capacitor C8 serves as the other output terminal of module 10.

[0090] Full-bridge controlled rectifier circuits or half-bridge controlled rectifier circuits have two operating modes. The first is the modulation rectification mode, which means that the rectifier switch is turned on or off at a certain frequency. The second is the uncontrolled rectification mode, which means that the rectifier switch is turned on all the time.

[0091] When the rectifier unit 13 is a full-bridge controllable rectifier circuit or a half-bridge controllable rectifier circuit, when the first switching unit 12 of a certain module 10 is in bypass mode, then the module 10 is in bypass mode.

[0092] When the rectifier unit 13 is a full-bridge controlled rectifier circuit or a half-bridge controlled rectifier circuit, if the first switching unit 12 of a certain module 10 is in open-circuit mode, the rectifier unit 13 of that module 10 operates in uncontrolled rectification mode, and thus the module 10 is in uncontrolled rectification mode. If the first switching unit 12 of a certain module 10 is in open-circuit mode, the rectifier unit 13 of that module 10 operates in modulated rectification mode, and thus the module 10 is in modulated mode.

[0093] When the rectifier unit 13 is a full-bridge controlled rectifier circuit or a half-bridge controlled rectifier circuit, when the first switching unit 12 of a certain module 10 is in modulation mode, that module 10 is also in modulation mode. More specifically, if the first switching unit 12 of the module 10 receives a conduction signal, the rectifier unit 13 of the module 10 operates in uncontrolled rectification mode, that is, no drive signal is provided to the rectifier switch. If the first switching unit 12 of the module 10 receives a turn-off signal, the rectifier unit 13 of the module 10 operates in synchronous rectification mode, that is, a drive signal is provided to the rectifier switch when the freewheeling diode of the rectifier switch is about to conduct.

[0094] In one embodiment, m1 modules 10 operate in the bypass mode, where 0 ≤ m1 ≤ M1. m2 modules 10 operate in the uncontrolled rectification mode, where 0 ≤ m2 ≤ M2. m3 modules 10 operate in the modulation mode, and the modules 10 operating in the modulation mode can achieve power factor correction, where 0 < m3. Here, m1 + m2 + m3 = N, M1 is the maximum number of modules that can be bypassed, M2 is the maximum number of modules that can operate in the uncontrolled rectification mode, and N is the total number of modules in the power supply device.

[0095] Here, M1 is determined by the ratio of the voltage of the power grid to the voltage that the primary winding 111 of the transformer 11 of a single module can withstand, M2 is determined by the degree of current distortion allowed by the power grid, and M2 does not exceed N / 2. For example: Suppose in a 10 kV power supply device, the voltage that each module 10 can withstand is 1 kV, and N = 12, that is, there are 12 modules in the power supply device, then 2 modules are allowed to be in the bypass mode, that is, M1 = 2.

[0096] In the above technical solution, by adopting the first switching unit, both the bypass function and the power factor correction can be achieved, which can simplify the internal circuit structure of the module and also reduce the cost of the power supply device. And the ratio of the voltage of the power grid to the voltage that the primary winding 111 of the transformer 11 of a single module can withstand determines the maximum number M1 of modules allowed to be in the bypass mode, which can avoid burning out the modules in the modulation mode or the uncontrolled rectification mode due to excessive modules in the bypass mode causing too much voltage on them. Setting M2 not to exceed N / 2 can ensure the quality of the electric energy output by the power supply device.

[0097] In one embodiment, the m3 modules 10 operating in the modulation mode adopt the carrier phase-shifted modulation method, that is, m3 modules 10 are selected from N modules 10, and the first switching unit 12 in the m3 modules 10 is controlled by the carrier phase-shifted modulation method. When the rectification unit 13 in each module 10 is a full-bridge controlled rectifier circuit and a half-bridge controlled rectifier circuit, the first switching unit 12 and the rectification unit 13 in each module 10 can adopt the carrier synchronization mode.

[0098] In one embodiment, the carrier phases of the m3 modules 10 operating in the modulation mode differ by 2π / m3 in sequence.

[0099] In the above technical solution, by connecting the primary windings 111 of the converters in each module 10 in series, carrier phase-shifted modulation can be performed on the modules 10 in the modulation mode, reducing the AC filter and DC capacitor in the module 10 and simplifying the internal circuit structure of the module 10.

[0100] In one embodiment, the m3 modules 10 operating in the modulation mode all adopt current closed-loop and voltage feed-forward control. Figure 7A schematic diagram of current closed-loop control and voltage feedforward control provided in an embodiment of this application is shown below. Figure 7 As shown, I dref For active current reference, I qref For reactive current reference, cosθ A sinθ is the cosine function of the grid voltage angle. A I is a sinusoidal function of the grid voltage angle. gref As an AC current reference, it is synchronized with the grid voltage, i g For grid current feedback, V bkref V is the modulation voltage reference value for the kth module 10 in modulation mode. ff It is a voltage feedforward.

[0101] Active current reference I dref cosθ, the cosine function of the grid voltage angle A The first current reference value is obtained after processing by the first multiplier; the reactive current reference I is... qref sinθ, the sinusoidal function of the grid voltage angle A The second current reference value is obtained after processing by the second multiplier. The first current reference value and the second current reference value are then processed by the first subtractor to obtain the AC current reference I. gref AC current reference I gref and grid current feedback i g After processing by the second subtractor, the first intermediate variable is obtained. This first intermediate variable is then processed by the current proportional controller P to output the second intermediate variable. The second intermediate variable and the feedforward voltage V... ff After processing by the third subtractor, the output is the modulation voltage reference value V of the kth module 10 in modulation mode. bkref Where k = 1, 2, ..., m3.

[0102] In one embodiment, the feedforward voltage V ff The calculation formula is:

[0103]

[0104] Among them, V gA Let i be the voltage of the power grid. g Let V be the current flowing through the power grid, sign be the sign function, and V be the current. dch The value represents the DC side voltage of the rectifier unit 13 of the h-th module 10 in uncontrolled rectification mode, where h = 1, 2, ..., m2.

[0105] In the above formula, the numerator represents the difference between the grid voltage and the total voltage at the output terminals of the m2 modules 10 operating in uncontrolled rectification mode, and the denominator represents the number of modules in modulation mode. In other words, the feedforward voltage is the difference in the numerator that is evenly distributed among the modules in modulation mode.

[0106] The modulation voltage reference value V of the kth module 10 in modulation mode is obtained. bkref Then, the modulation voltage reference value V bkref Compared with the carrier wave, drive signals for the first switch T1 and the second switch T2 in the first switching unit 12 are generated.

[0107] By introducing voltage feedforward control, for Figure 3 and Figure 4 The power supply device shown, namely the rectifier unit 13, is a power supply device for an uncontrolled rectifier circuit. The module with the bidirectional switch in modulation mode eliminates the influence of the module with the bidirectional switch in open circuit through feedforward control, thereby realizing the fault-tolerant control function.

[0108] In some embodiments, the DC sides of the rectifier units 13 of the N modules 10 are connected in parallel, such as... Figures 3 to 6 As shown. In other embodiments, the DC sides of the rectifier units 13 of the N modules 10 are connected in series, such as... Figure 8 As shown. By connecting the DC side of rectifier unit 13 in series, a higher voltage can be output from the power supply system.

[0109] In one embodiment, such as Figure 9 As shown, the transformer 11 of each module 10 is a multi-winding transformer, and each transformer 11 of each module 10 also includes a second secondary winding 113. The second secondary windings 113 of the transformers 11 of N modules 10 are connected in series to form an AC power supply port. This AC power supply port can provide power to AC loads and can also serve as an interface for new energy sources or energy storage.

[0110] In one embodiment, such as Figure 10Each module 10 has a multi-winding transformer 11, and each module 10 also includes a third secondary winding 114. Each module 10 also includes a second switching unit 14. Within the same module 10, the third secondary winding 114 and the second switching unit 14 are connected. The first switching unit 12 of the first module is connected to the first secondary winding 112 of the transformer 11 of the first module, and the second switching unit 14 of the first module is connected to the third secondary winding 114 of the transformer 11 of the first module. Similarly, the first switching unit 12 of the second module is connected to the first secondary winding 112 of the transformer 11 of the second module, and the second switching unit 14 of the second module is connected to the third secondary winding 114 of the transformer 11 of the second module. And so on, the first switching unit 12 of the Nth module is connected to the first secondary winding 112 of the transformer 11 of the Nth module, and the second switching unit 14 of the Nth module is connected to the third secondary winding 114 of the transformer 11 of the Nth module.

[0111] Each module 10 also includes a rectifier unit 15, which is connected to the third secondary winding 114. The structure of the rectifier unit 15 is the same as that of the rectifier unit 14, and will not be described again here.

[0112] exist Figure 10 In the power supply device shown, each module 10 corresponding to each transformer 11 adopts a carrier phase-shifting mode. Multiple secondary sides of the same transformer 11 within the same module 10 can adopt either a carrier synchronization mode or a carrier phase-shifting mode, meaning the carrier phases of each module 10 are different. The carrier phases of the first switching unit 12 and the second switching unit 14 within each module 10 can be the same or different. In this scheme, by using multi-winding transformers 11 in the module 10, the number of transformers 11 can be reduced.

[0113] Figure 11 This is a schematic diagram of a three-phase power supply system provided in an embodiment of this application, as shown below. Figure 11 As shown, the three-phase power supply system includes three power supply devices, which are connected to the three phases of a three-phase power supply via a Y-connection or a delta connection. A module 10 is taken from each of the three power supply devices to form a three-phase module 20.

[0114] When module 10 in the power supply device is Figures 3 to 6In the structure shown, where each module 10 includes a transformer 11 with a first secondary winding 112 and each module 10 includes a first switching unit 12, each three-phase module 20 contains three single-phase transformers 11 and three first switching units 12. Because the double-frequency power of each phase cancels each other out, the requirement for DC-Link capacitors is reduced. The three-phase modules 20 can share control signals, and zero-sequence components can be injected into the three-phase modules 20 to improve waveform and increase DC voltage utilization.

[0115] Figure 12 A control method for a power supply device provided in an embodiment of this application includes the following steps:

[0116] S301 provides N modules.

[0117] Where N is a positive integer greater than or equal to 2, each module 10 includes a transformer and a first switching unit, the transformer includes a primary winding and a first secondary winding, the first switching unit is connected to the first secondary winding of the transformer, and the primary windings of the transformers of N modules 10 are connected in series.

[0118] In one embodiment, each module 10 further includes a rectifier unit having an AC side and a DC side, the AC side of the rectifier unit being connected to the first secondary winding of the transformer.

[0119] S302, Control the first switching unit to operate in one of the following modes: bypass mode, open circuit mode, and modulation mode.

[0120] In this context, the first switching unit operating in bypass mode means that the first switching unit is on for an extended period of time; operating in open-circuit mode means that the first switching unit is off; and operating in modulation mode means that the first switching unit is on and off at a certain frequency. By switching the operating mode of the first switching unit, the system controls whether each module 10 outputs data or the magnitude of the output voltage.

[0121] In the above technical solution, the power supply device includes N modules 10, and each module 10 contains a transformer and a first switching unit. The first switching unit controls the output of each module 10, so that the power supply device can provide voltages of different amplitudes according to power demand. Moreover, through modular design, there is no need to use large and heavy transformers such as centralized power frequency transformers or multi-winding transformers, which facilitates the transportation and maintenance of the power supply device.

[0122] Figure 13 A control method for a power supply device provided in an embodiment of this application includes the following steps:

[0123] S401 provides N modules.

[0124] Where N is a positive integer greater than or equal to 2, each module 10 includes a transformer, a first switching unit and a rectifier unit, the transformer includes a primary winding and a first secondary winding, the first switching unit is connected to the first secondary winding of the transformer, the primary windings of the transformers of N modules 10 are connected in series, the rectifier unit has an AC side and a DC side, and the AC side of the rectifier unit is connected to the first secondary winding of the transformer.

[0125] S402, Control the first switching unit to operate in one of the following modes: bypass mode, open circuit mode, and modulation mode.

[0126] This step has already been described in detail in section 302, and will not be repeated here.

[0127] S403 controls m1 modules to operate in bypass mode, controls m2 modules to operate in uncontrolled rectification mode, and controls m3 modules to operate in modulation mode to achieve power factor correction.

[0128] Where 0≤m1≤M1, 0≤m2≤M2, 0≤m3, m1+m2+m3=N, M1 is the maximum number of modules that can be bypassed, and M2 is the maximum number of modules that can be opened.

[0129] Specifically, when the rectifier unit is a full-bridge uncontrolled rectifier circuit or a half-bridge uncontrolled rectifier circuit, controlling the first switching unit of m1 modules 10 to be in bypass mode controls m1 modules 10 to be in bypass mode. Controlling the first switching unit of m2 modules 10 to be in open-circuit mode controls m2 modules 10 to be in uncontrolled rectification mode. Controlling the first switching unit of m3 modules 10 to be in modulation mode controls m3 modules 10 to be in modulation mode.

[0130] When the rectifier unit is a full-bridge controlled rectifier circuit or a half-bridge controlled rectifier circuit, if the first switching unit of each of the m1 modules 10 is in bypass mode, then module 10 is in bypass mode. If the first switching unit of each of the m2 modules 10 is in open-circuit mode, then the rectifier unit of each of the m2 modules 10 is in uncontrolled rectification mode, thus controlling each of the m2 modules 10 to be in uncontrolled rectification mode. If the first switching unit of each of the m3 modules 10 is in open-circuit mode, then the rectifier unit of each of the m3 modules 10 is in modulated rectification mode, thus controlling each of the m3 modules 10 to be in modulated mode.

[0131] In one embodiment, when the rectifier unit is a full-bridge controlled rectifier circuit or a half-bridge controlled rectifier circuit, controlling the first switching unit of each of the m3 modules 10 to be in modulation mode also controls the m3 modules 10 to be in modulation mode. More specifically, for a certain module 10 among the m3 modules 10, when the first switching unit of module 10 is in modulation mode and receives a turn-on signal, the rectifier unit of module 10 is controlled to operate in uncontrolled rectification mode, that is, no drive signal is provided to the rectifier switch. If the first switching unit of module 10 receives a turn-off signal, the rectifier unit of module 10 is controlled to operate in synchronous rectification mode, that is, a drive signal is provided to the rectifier switch when the freewheeling diode of the rectifier switch is about to be turned on.

[0132] In one embodiment, the m3 modules 10 operating in the modulation mode are controlled by carrier phase-shift modulation. The first switching unit in the m3 modules 10 is controlled by carrier phase-shift modulation. When the rectifier unit in each module 10 is a full-bridge controllable rectifier circuit and a half-bridge controllable rectifier circuit, the first switching unit and rectifier unit in each module 10 can adopt carrier synchronization mode.

[0133] In one embodiment, the carrier phases of the m3 modules 10 operating in modulation mode are sequentially differed by 2π / m3.

[0134] In one embodiment, the primary windings of the transformers of N modules 10 are connected in series to a power grid. All m3 modules 10 operating in modulation mode employ current closed-loop and voltage feedforward control, with a feedforward voltage V. ff The calculation formula is:

[0135]

[0136] Among them, V gA Let i be the voltage of the power grid. g Let V be the current flowing through the power grid, sign be the sign function, and V be the current. dch This represents the DC-side voltage of the rectifier unit of the h-th module 10 in uncontrolled rectification mode.

[0137] like Figure 14 As shown, if the rectifier unit is an uncontrolled rectifier circuit, the control methods include:

[0138] S501. In N modules, the control cycle of the kth module begins.

[0139] S502. Check if the k-th module itself is faulty. If so, proceed to S504; otherwise, proceed to S503.

[0140] Common faults in module 10 include malfunctions in the first switching unit and the rectifier unit. Malfunctions in the first switching unit include open or short circuits in the switches within the unit. Malfunctions in the rectifier unit include short circuits or open circuits in the diodes.

[0141] S503, put the kth module into modulation mode.

[0142] Specifically, the first switching unit within the k-th module is controlled to operate in modulation mode, so that the k-th module operates in modulation mode.

[0143] S504. Continue to determine whether the fault type is an open circuit fault of the first switch unit. If yes, proceed to S505; otherwise, proceed to S507.

[0144] S505. Continue to determine whether the number of modules in the N modules that are already in uncontrolled rectification mode is less than M2. If yes, proceed to S506; otherwise, proceed to S509.

[0145] S506. If there is a fault and the fault type is an open circuit fault of the first switching unit, when the number of modules in the N modules that are already in uncontrolled rectification mode is less than M2, the kth module is made to enter uncontrolled rectification mode.

[0146] Specifically, when the fault type of the module is a fault in the first switching unit (meaning the rectifier unit is not faulty), the module can operate in uncontrolled rectification mode but cannot operate in modulation mode or bypass mode. If the number of modules already in uncontrolled rectification mode out of N modules is less than M2, then the kth module is controlled to enter uncontrolled rectification mode, increasing the number of modules in uncontrolled rectification mode by one.

[0147] S507. Continue to determine whether the number of modules in bypass mode among the N modules is less than M1. If yes, proceed to S508; otherwise, proceed to S509.

[0148] S508. If there is a fault and the fault type is not an open circuit fault of the first switch unit, and the number of modules in the N modules that are already in bypass mode is less than M1, then the kth module shall enter bypass mode.

[0149] Specifically, when the fault type of a module is not a fault of the first switching unit (i.e., a fault of the rectifier unit), the module can operate in bypass mode but cannot operate in modulation mode or uncontrolled rectification mode. If the number of modules already in bypass mode out of N modules is less than M1, then the kth module is controlled to enter bypass mode, increasing the number of modules in bypass mode by one.

[0150] S509, System shutdown.

[0151] If there is a fault and the fault type is an open circuit fault of the first switching unit, and the number of modules in the N modules that are already in uncontrolled rectification mode is equal to M2, if the kth module is controlled to enter uncontrolled rectification mode, the number of modules that are already in uncontrolled rectification mode will be greater than M2. Therefore, the control system will shut down in this case.

[0152] If there is a fault and the fault type is not an open circuit fault of the first switch unit, and the number of modules in the N modules that are already in bypass mode is equal to M1, if the kth module is controlled to enter bypass mode, the number of modules that are already in bypass mode will be greater than M1. Therefore, the control system will shut down in this case.

[0153] like Figure 15 As shown, if the rectifier unit is a controllable rectifier circuit, the control method includes:

[0154] S601. In N modules, the control cycle begins for the kth module.

[0155] S602. Check if the k-th module itself is faulty. If so, proceed to S604; otherwise, proceed to S603.

[0156] Common faults in module 10 include malfunctions in the first switching unit and malfunctions in the rectifier unit. Malfunctions in the first switching unit include open circuits or short circuits in the switches within the unit. Malfunctions in the rectifier unit include open circuits or short circuits in the rectifier switches.

[0157] S603. If there is no fault, put the kth module into modulation mode.

[0158] In one implementation, the first switching unit within the k-th module is controlled to operate in modulation mode, thereby enabling the k-th module to operate in modulation mode. In another implementation, the first switching unit within the k-th module is controlled to operate in open-circuit mode, and the rectifier unit is controlled to operate in modulation-rectification mode, thereby enabling the k-th module to operate in modulation mode.

[0159] S604. Continue to determine whether the fault type is an open circuit fault of the first switch unit. If yes, proceed to S605; otherwise, proceed to S606.

[0160] S605. If there is a fault and the fault type is an open circuit fault of the first switching unit, the rectifier unit of the kth module is used for modulation so that the kth module enters the modulation mode.

[0161] When the first switching unit is in an open-circuit fault, the rectifier unit can be controlled to be in modulation rectification mode, so that the module is in modulation mode, thereby increasing the number of modules in modulation mode by one.

[0162] S606. Continue to determine whether the number of modules in bypass mode among the N modules is less than M1. If yes, proceed to S607; otherwise, proceed to S608.

[0163] S607. If there is a fault and the fault type is not an open circuit fault of the first switch unit, and the number of modules in the N modules that are already in bypass mode is less than M1, then the kth module shall enter bypass mode.

[0164] If there is a fault and the fault type is not an open circuit fault of the first switching unit, that is, if the module fault is a rectifier unit fault, then the module can only operate in bypass mode and cannot operate in modulation mode or uncontrolled rectification mode. If the number of modules already in bypass mode among the N modules is less than M1, then the kth module is controlled to enter bypass mode, thereby increasing the number of modules in bypass mode by one.

[0165] S608, System shutdown.

[0166] If the number of modules already in bypass mode out of N modules is equal to M1, and if the kth module is further controlled to enter bypass mode, the number of modules already in bypass mode will be greater than M1. Therefore, in this case, the control system will shut down.

[0167] The above technical solution provides a fault-tolerant method after a module fails, so that the power supply device can continue to operate and improve the reliability of the power supply device.

[0168] Finally, it should be noted that 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 skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A power supply device, characterized in that, Comprising: N modules, where N is a positive integer greater than or equal to 2, and each of the said modules comprises: A transformer, comprising a primary winding and a first secondary winding; and A first switching unit, connected to the first secondary winding of the said transformer, wherein, the primary windings of the transformers of the N modules are connected in series, and the first switching unit operates in one of a bypass mode, an open-circuit mode, and a modulation mode; Each of the said modules further comprises: a rectification unit, having an AC side and a DC side, the AC side of the rectification unit being connected to the first secondary winding of the transformer; wherein, the rectification unit is a full-bridge controllable rectification circuit, a full-bridge uncontrolled rectification circuit, a half-bridge controllable rectification circuit, or a half-bridge uncontrolled rectification circuit; if the rectification unit is a full-bridge controllable rectification circuit, when the first switching unit of a certain module is in the modulation mode, if the first switching unit of this module receives a conduction signal, then the rectification unit of this module operates in an uncontrolled rectification mode, if the first switching unit of this module receives a cut-off signal, then the rectification unit of this module operates in a synchronous rectification mode.

2. The power supply device according to claim 1, characterized in that, m1 of the said modules operate in the bypass mode, 0 ≤ m1 ≤ M1; m2 of the said modules operate in the uncontrolled rectification mode, 0 ≤ m2 ≤ M2; m3 of the said modules operate in the modulation mode and can achieve power factor correction, 0 < m3; where m1 + m2 + m3 = N, M1 is the maximum number of modules that can be bypassed, and M2 is the maximum number of modules that can operate in the uncontrolled rectification mode.

3. The power supply device according to claim 2, characterized in that, The m3 modules operating in the modulation mode adopt a carrier phase-shifted modulation method.

4. The power supply device according to claim 3, characterized in that, The carrier phases of the m3 modules operating in the modulation mode differ by 2π / m3 in sequence.

5. The power supply device according to claim 2, characterized in that, The primary windings of the transformers of the N modules are connected in series to a power grid.

6. The power supply device according to claim 5, characterized in that, The M1 is determined by the ratio of the voltage of the power grid to the voltage that the primary winding of the transformer of a single module can withstand, the M2 is determined by the degree of current distortion allowed by the power grid, and the M2 does not exceed N / 2.

7. The power supply device according to claim 5, characterized in that, All m3 modules operating in modulation mode employ current closed-loop and voltage feedforward control, wherein the feedforward voltage V ff The calculation formula is: Among them, V gA Let i be the voltage of the power grid. g Let V be the current flowing through the power grid, sign be the sign function, and V be the current. dch This represents the DC-side voltage of the rectifier unit in the h-th module, which is in uncontrolled rectification mode.

8. The power supply device according to claim 1, characterized in that, The DC sides of the rectification units of the N modules are connected in series or in parallel.

9. The power supply device according to claim 1, characterized in that, The transformer of each of the said modules further comprises a second secondary winding, and the second secondary windings of the transformers of the N modules are connected in series to form an AC power supply port.

10. The power supply device according to claim 1, characterized in that, The transformer of each of the said modules further comprises a third secondary winding, and each of the said modules further comprises a second switching unit, and the third secondary winding and the second switching unit within the same module are connected.

11. A three-phase power supply system, characterized in that, Comprising: Three power supply devices as claimed in claim 1, connected to the three phases of a three-phase power supply in a Y-connection or delta-connection manner.

12. The power supply system according to claim 11, characterized in that, One module is taken out from each of the three power supply devices respectively to form a three-phase module.

13. A control method for a power supply device, characterized in that N modules are provided, where N is a positive integer greater than or equal to 2, and each of the said modules comprises: A transformer, comprising a primary winding and a first secondary winding; and A first switching unit, connected to the first secondary winding of the said transformer, wherein, the primary windings of the transformers of the N modules are connected in series; and The first switching unit is controlled to operate in one of the following modes: bypass mode, open-circuit mode, and modulation mode. Each module further includes: a rectifier unit having an AC side and a DC side, wherein the AC side of the rectifier unit is connected to the first secondary winding of the transformer; wherein the rectifier unit is a full-bridge controlled rectifier circuit, a full-bridge uncontrolled rectifier circuit, a half-bridge controlled rectifier circuit, or a half-bridge uncontrolled rectifier circuit; if the rectifier unit is a full-bridge controlled rectifier circuit, when the first switching unit of a certain module is in modulation mode, if the first switching unit of the module receives a conduction signal, the rectifier unit of the module operates in uncontrolled rectification mode; if the first switching unit of the module receives a turn-off signal, the rectifier unit of the module operates in synchronous rectification mode.

14. The control method according to claim 13, characterized in that, include: Control m1 modules to operate in bypass mode, where 0 ≤ m1 ≤ M1; Control m2 modules to operate in uncontrolled rectification mode, where 0 ≤ m2 ≤ M2; as well as Controlling m3 of the aforementioned modules to operate in modulation mode enables power factor correction, where 0 ≤ m3. Where m1+m2+m3=N, M1 is the maximum number of modules that can be bypassed, and M2 is the maximum number of modules that can operate in uncontrolled rectification mode.

15. The control method according to claim 14, characterized in that, If the rectifier unit is an uncontrolled rectifier circuit, the control method includes: In the N modules, for the kth module, after the start of its control cycle, it is checked whether the kth module itself has a fault; If there is no fault, the kth module will enter modulation mode; If there is a fault and the fault type is an open circuit fault of the first switching unit, and the number of modules in the N modules that are already in uncontrolled rectification mode is less than M2, then the kth module is made to enter uncontrolled rectification mode; otherwise, the system is shut down. If there is a fault and the fault type is not an open circuit fault of the first switch unit, and the number of modules in the N modules that are already in bypass mode is less than M1, then the kth module is put into bypass mode; otherwise, the system is shut down.

16. The control method according to claim 14, characterized in that, If the rectifier unit is a controllable rectifier circuit, the control method includes: In the N modules, for the kth module, after the start of its control cycle, it is checked whether the kth module itself has a fault; If there is no fault, the k-th module will enter modulation mode; If there is a fault and the fault type is an open circuit fault of the first switching unit, the rectifier unit of the kth module is used for modulation to make the kth module enter the modulation mode. If there is a fault and the fault type is not an open circuit fault of the first switch unit, and the number of modules in the N modules that are already in bypass mode is less than M1, then the kth module is put into bypass mode; otherwise, the system is shut down.

17. The control method according to claim 14, characterized in that, The m3 modules operating in modulation mode are controlled using carrier phase-shift modulation.

18. The control method according to claim 17, characterized in that, The carrier phases of the m3 modules operating in modulation mode are successively 2π / m3 apart.

19. The control method according to claim 14, characterized in that, The primary windings of the transformers in the N modules are connected in series to a power grid. All m3 modules operating in modulation mode employ current closed-loop and voltage feedforward control, with a feedforward voltage V. ff The calculation formula is: Among them, V gA Let i be the voltage of the power grid. g Let V be the current flowing through the power grid, sign be the sign function, and V be the current. dch This represents the DC-side voltage of the rectifier unit in the h-th module, which is in uncontrolled rectification mode.

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