Common ground voltage boosting module, y-type inverter and control method

Abstract

This invention discloses a common-ground boost module, a Y-type inverter, and a control method, belonging to the field of power electronics technology. It includes: inductors L1 and L2, capacitors C1, C2, and C3, and switching transistors S1, S2, and S3. One end of inductor L1 is connected to the positive terminal of the input voltage, and the other end is connected to the drain of switching transistor S1. The source of S1 is connected to the negative terminal of the input voltage. The drain of S1 is also connected to the source of S2. The drain of S2 is connected to one end of capacitor C1, and the other end of capacitor C1 is connected to the negative terminal of the input voltage. One end of inductor L2 is connected to the drain of S2. The other end of inductor L2, one end of capacitor C2, and the source of S3 form a Y-type connection. The other end of capacitor C2 is connected to the drain of S1, and the drain of S3 is connected to one end of capacitor C3. The other end of capacitor C3 is connected to the negative terminal of the input voltage, and capacitor C3 is connected in parallel with the output side to achieve a common ground for input and output. Compared with traditional boost circuits, this invention can achieve a higher boost ratio.

Description

Technical Field

[0001] This invention belongs to the field of power electronics technology, and more specifically, relates to a common-ground boost module, a Y-type inverter, and a control method. Background Technology

[0002] In renewable energy grid-connected systems, the inverter, as the connection between renewable energy and the grid, has a topology that determines the overall system cost and efficiency. Traditional inverter topologies often require a high DC-side voltage during grid-connected operation, needing the DC-side voltage to be greater than or equal to the AC-side line voltage amplitude. Simultaneously, due to the inherent characteristics of renewable energy generation and the need to achieve maximum power point tracking, a boost converter topology is often added before the inverter; however, this reduces the inverter's efficiency and power density. Therefore, a boost inverter structure combining a boost converter topology with the inverter structure can be adopted, such as a differential boost inverter.

[0003] However, due to its inherent nonlinearity, the differential boost inverter has limitations on the range of duty cycle variation and the magnitude of inductor current, which limits the boost ratio and consequently restricts the output voltage range of the differential boost inverter.

[0004] A double-dual structure refers to a structure where the inputs are connected in reverse parallel and the outputs are connected in forward series. It has advantages such as low input current ripple, modular structure, and high boost ratio. However, since the input and output of a double-dual structure are not grounded, the double-dual boost circuit only has the advantage of a high boost ratio in a single-phase structure. When directly combined with a multi-phase inverter structure, it cannot improve the boost ratio compared with Y-type inverters such as differential boost inverters. Summary of the Invention

[0005] To address the shortcomings and improvement needs of existing technologies, this invention provides a common-ground boost module, a Y-type inverter, and a control method. The purpose is to provide a common-ground boost module with a high boost ratio, which, when applied to a multiphase inverter, can improve the inverter's boost ratio and thus increase the inverter's output voltage range.

[0006] To achieve the above objectives, according to a first aspect of the present invention, a common-ground boost module is provided, comprising: inductor L1, inductor L2, capacitor C1, capacitor C2, capacitor C3, switching transistor S1, switching transistor S2, and switching transistor S3;

[0007] One end of the inductor L1 is connected to the positive terminal of the input voltage, and the other end is connected to the drain of the switching transistor S1. The source of the switching transistor S1 is connected to the negative terminal of the input voltage. The drain of the switching transistor S1 is also connected to the source of the switching transistor S2. The drain of the switching transistor S2 is connected to one end of the capacitor C1, and the other end of the capacitor C1 is connected to the negative terminal of the input voltage.

[0008] One end of the inductor L2 is connected to the drain of the switching transistor S2, and the other end of the inductor L2, one end of the capacitor C2, and the source of the switching transistor S3 form a Y-connection; the other end of the capacitor C2 is connected to the drain of the switching transistor S1, and the drain of the switching transistor S3 is connected to one end of the capacitor C3; the other end of the capacitor C3 is used to connect to the negative terminal of the input voltage, and the capacitor C3 is connected in parallel with the output side to achieve a common ground for the input and output.

[0009] Furthermore, the switching transistors S1, S2, and S3 are IGBTs, MOSFETs, or GaN.

[0010] According to a second aspect of the present invention, a single-phase inverter is provided, comprising two converters, the output of each converter being connected to both ends of a load, wherein the converter is the common-ground boost module described in the first aspect.

[0011] According to a third aspect of the present invention, a Y-type inverter is provided, comprising a three-phase structure, wherein the output of each phase structure is connected to a corresponding load, and the phase structures are connected in a Y-shape to each other, wherein each phase structure is a common-ground boost module as described in the first aspect.

[0012] According to a fourth aspect of the present invention, a dual-loop control method for an inverter as described in the second or third aspect is provided, comprising:

[0013] Duty cycle D of switch S1 is obtained using dual-loop control;

[0014] The output voltage of the inverter is controlled by the duty cycle D.

[0015] Furthermore, the duty cycle D of the switching transistor S1 is obtained using dual-loop control, including:

[0016] The command value V of the output voltage o_REF With the actual output voltage V o The difference is used for voltage loop control to obtain the current command value i of capacitor C3 within one cycle. C3_REF ;

[0017] According to the current command value i of capacitor C3 C3_REF Based on the principle of power conservation, the current command value i of inductor L1 within one cycle is obtained. L1_REF;

[0018] The current command value i of inductor L1 L1_REF The actual value of the current i in inductor L1 L1 The difference is used for inductor current loop control to obtain the voltage command value V of inductor L1 within one cycle. L1_REF Thus, the duty cycle D of the switching transistor S1 can be obtained.

[0019] Furthermore, the duty cycles of the switching transistors S2 and S3 are 1-D, and both are complementary to the switching transistor S1 in conducting.

[0020] Furthermore, the voltage command value V of inductor L1 within one cycle L1_REF The duty cycle D of the switching transistor S1 satisfies the following:

[0021]

[0022] Among them, V in The input voltage for a single-phase structure or a single converter; V C1 The voltage across capacitor C1 is given.

[0023] Furthermore, based on the current command value i of capacitor C3 C3_REF Based on the principle of power conservation, the current command value i of inductor L1 within one cycle is obtained. L1_REF for:

[0024]

[0025] Among them, i o V represents the output current value of a single-phase structure or a single converter. in The input voltage, V, is for a single-phase structure or a single converter. o This refers to the output voltage of a single-phase structure or a single converter.

[0026] Furthermore, the voltage loop control is either PI control or PIR control;

[0027] The inductor current loop control is either PI control or PIR control.

[0028] In summary, the above-described technical solutions conceived in this invention can achieve the following beneficial effects:

[0029] (1) This invention constructs a novel common-ground boost module topology using inductors, capacitors, and switching transistors. Based on this topology, and according to the volt-second balance principle of inductors and the relationship between input and output, the boost ratio of this common-ground boost module can be obtained as follows: (D is the duty cycle), achieving the same boost ratio as the dual-dual boost circuit; compared to the boost ratio of traditional technology, which is... This invention achieves a higher boost ratio and enables bidirectional power flow. Furthermore, since the boost module of this invention shares a common ground for both input and output, it can still achieve the same high boost ratio when applied to multiphase inverters. Attached Figure Description

[0030] Figure 1 This is a topology diagram of the common-ground boost module of the present invention.

[0031] Figure 2 This is a topology diagram of the Y-type inverter of the present invention.

[0032] Figure 3 This is a first switching state topology diagram of the single-phase topology of the Y-type inverter of the present invention.

[0033] Figure 4 This is a second switching state topology diagram of the single-phase topology of the Y-type inverter of the present invention.

[0034] Figure 5 This is the topology diagram of an existing dual-dual boost circuit.

[0035] Figure 6 This is a diagram of the inductor current loop control structure of the single-phase Y-type inverter of the present invention.

[0036] Figure 7 This is a diagram of the output voltage loop control structure of the single-phase Y-type inverter of the present invention.

[0037] Figure 8 The output phase voltage simulation diagram of the three-phase structure of the Y-type inverter of the present invention under dual closed-loop control is shown.

[0038] Figure 9 The output phase current simulation diagram of the three-phase structure of the Y-type inverter of the present invention under dual closed-loop control is shown. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0040] like Figure 1 As shown, the common-ground boost module provided by the present invention mainly includes: inductor L1, inductor L2, capacitor C1, capacitor C2, capacitor C3, switching transistor S1, switching transistor S2 and switching transistor S3.

[0041] One end of inductor L1 is connected to the positive terminal of the input voltage, and the other end of inductor L1 is connected to the drain of switch S1. The source of switch S1 is connected to the negative terminal of the input voltage. The drain of switch S1 is also connected to the source of switch S2. The drain of switch S2 is connected to one end of capacitor C1, and the other end of capacitor C1 is connected to the negative terminal of the input voltage.

[0042] One end of inductor L2 is connected to the drain of switching transistor S2, and the other end of inductor L2, one end of capacitor C2, and the source of switching transistor S3 form a Y-connection; the other end of capacitor C2 is connected to the drain of switching transistor S1, and the drain of switching transistor S3 is connected to one end of capacitor C3; the other end of capacitor C3 is used to connect to the negative terminal of the input voltage, and capacitor C3 is connected in parallel with the output side to achieve a common ground for input and output.

[0043] Preferably, switching transistors S1, S2, and S3 can be any suitable semiconductor switching device as needed, including but not limited to IGBT, MOSFET, GaN, etc.

[0044] Based on the aforementioned common-ground boost module, the present invention also provides a single-phase inverter, comprising two identical converters, each converter being the aforementioned common-ground boost module; the output of each converter is connected to both ends of the load.

[0045] Furthermore, such as Figure 2 As shown, based on the above-mentioned common-ground boost module, the present invention also provides a Y-type inverter, including a three-phase structure, each phase structure being the above-mentioned common-ground boost module, the output of each phase structure being connected to the load corresponding to each phase structure, and the three phase structures being connected in a Y-shape.

[0046] Specifically, the common-ground boost module provided by this invention has a high boost ratio, and the two switching states of the common-ground boost module of this invention are as follows: Figure 3 and Figure 4 As shown (taking positive power flow as an example), where, Figure 3 This is the first switching state; Figure 4 This is the second switching state. In the first switching state, switch S1 is turned on, while switches S2 and S3 are turned off. In this state, inductors L1 and L2 and capacitor C2 are charged, while capacitors C1 and C3 are discharged. In this state, the voltages across inductors L1 and L2 satisfy the following equation:

[0047] V L1 =V in (1)

[0048] V L2 =V C1 -V C2 (2)

[0049] Among them, V L1 and V L2 These are the voltages across inductors L1 and L2 in a single-phase structure, respectively; V in The input voltage of the common-ground boost module, in the inverter structure of this invention, represents the input voltage of a single-phase structure or a single converter; V C1 and V C2 These are the voltages of capacitors C1 and C2 in a single-phase structure, respectively.

[0050] In the first switching state, switch S1 is off, and switches S2 and S3 are on. Inductors L1 and L2 and capacitor C2 discharge, while capacitors C1 and C3 charge. In this state, the inductor voltage satisfies the following equation:

[0051] V L1 =V in -V C1 =V in +V C2 -V o (3)

[0052] V L2 =-V C2 (4)

[0053] Among them, V o The output voltage of the common-ground boost module is indicated. In the inverter structure of this invention, the output voltage of a single-phase structure or a single converter is indicated.

[0054] Assuming D is the duty cycle of switch S1, then the duty cycles of switches S2 and S3 are 1-D, and both are complementary to switch S1 in conduction. Applying the volt-second balance principle of inductors to inductors L1 and L2, and neglecting the fluctuation of capacitor voltage within one cycle, we can obtain the following equation:

[0055] V C1 +V C2 =V o (5)

[0056] DV in +(1-D)(V in +V C2 -V o )=0 (6)

[0057] D(V C1 -V C2 )+(1-D)V C2 =0 (7)

[0058] The boost ratio M(D) of this common-ground boost module is shown in the following formula:

[0059]

[0060] As can be seen, this invention constructs a novel common-ground boost module topology using two inductors, three capacitors, and three switching transistors. Based on this topology, and according to the volt-second balance principle of inductors and the relationship between input and output, the boost ratio of this common-ground boost module can be obtained as follows: It achieved the same boost ratio as the dual-dual boost circuit; compared to traditional technology This invention achieves a higher boost ratio and enables bidirectional power flow. Furthermore, since the boost module of this invention shares a common ground for both input and output, it can still achieve the same high boost ratio when applied to multiphase inverters. The topology of the dual-dual boost circuit is shown below. Figure 5 As shown.

[0061] like Figure 6 and Figure 7 As shown, by performing output voltage loop control and inductor current loop control on the inverter of the present invention, and by changing the duty cycle D of the switching transistor S1 in each phase structure of the inverter or each converter, the output voltage range can be changed. Specifically, the dual-loop control method of the inverter of the present invention within one cycle includes:

[0062] The command value V of the output voltage o_REF With the actual output voltage V o The difference is input to the capacitor voltage controller for voltage loop control, obtaining the current command value i of capacitor C3 within one cycle. C3_REF ;

[0063] According to the current command value i of capacitor C3 C3_REF Based on the principle of power conservation, the current command value i of inductor L1 within one cycle is obtained. L1_REF ;

[0064] The current command value i of inductor L1 L1_REF The actual value of the current i in inductor L1 L1 The difference is input to the inductor current controller for inductor current loop control, obtaining the voltage command value V of inductor L1 within one cycle. L1_REF Thus, the duty cycle D of switch S1 is obtained; wherein, the duty cycles of switch S2 and switch S3 are 1-D, and both are complementary to switch S1 in conduction.

[0065] The duty cycle D is used to control the output voltage of the inverter; wherein the inverter is the single-phase inverter or the Y-type inverter mentioned above.

[0066] Preferably, the capacitor voltage controller is a PI controller or a PIR controller; the inductor current controller is a PI controller or a PIR controller.

[0067] Specifically, the average voltage of inductor L1 over one cycle can be obtained from (1) and (3). <V L1 >For:

[0068]

[0069] Among them, i L1 R represents the equivalent current of inductor L1 within one cycle, that is, the actual value of the current in inductor L1 within one cycle. L1 This represents the resistance of inductor L1.

[0070] After sorting, we can obtain:

[0071]

[0072] Therefore, in the control method of the present invention, the voltage command value V of inductor L1 within one cycle is... L1_REF The duty cycle D of the switching transistor S1 satisfies the following:

[0073] Similarly, based on the topology of this invention, and according to the principle of power conservation, the following equation can be obtained:

[0074]

[0075] Among them, i o This refers to the output current value of a single-phase structure or a single converter.

[0076] Therefore, based on the current command value i of capacitor C3 C3_REF Based on the principle of power conservation, the current command value i of inductor L1 within one cycle is obtained. L1_REF for:

[0077] The output phase voltage of the three-phase structure of the Y-type inverter of this invention under dual closed-loop control is as follows: Figure 8 As shown, the output phase current under dual closed-loop control is as follows: Figure 9 As shown in Table 1, the simulation parameters are R... L1 and R L2 The resistors for inductors L1 and L2 are shown below. It can be seen that this invention can directly output sinusoidal voltage and current with high waveform quality, achieve boost inverter operation, and obtain a wide output voltage range.

[0078] Table 1 Simulation Parameters

[0079]

[0080] This invention achieves the same high boost ratio using the same number of inductors as a dual-dual boost circuit and fewer switching transistors, without increasing the amount of new inductor cores or reducing the overall power density of the circuit. Furthermore, since the input and output share a common ground, it can still achieve the same high boost ratio and enable bidirectional power flow when applied to multiphase inverters.

[0081] It should be noted that the common-ground high boost ratio Y-type inverter topology provided by this invention is not only applicable to the scenario of new energy boost grid connection, but also applicable to any application scenario with requirements for boost ratio and power density.

[0082] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dual-loop control method for a single-phase inverter or a Y-type inverter, characterized in that, The single-phase inverter includes two converters, the outputs of which are respectively connected to the two ends of the load. The converter is a common-ground boost module. The Y-type inverter includes a three-phase structure, the output of each phase is respectively connected to the corresponding load, and the phases are connected in a Y-shape. Each phase is a common-ground boost module. The common-ground boost module includes: an inductor L 1. Inductor L 2. Capacitor C 1. Capacitor C 2. Capacitor C 3. Switching transistor S 1. Switching transistor S 2 and switching transistors S 3; The inductor L One end of 1 is used to connect to the positive terminal of the input voltage, and the other end is connected to the switching transistor. S 1. Drain connection, the switching transistor S The source of transistor 1 is connected to the negative terminal of the input voltage; the switching transistor S The drain of 1 is also connected to the switching transistor. S 2. Source connection, the switching transistor S The drain of 2 and the capacitor C One end of 1 is connected, the capacitor C The other end of 1 is used to connect to the negative terminal of the input voltage; The inductor L One end of 2 is connected to the switching transistor S The drain connection of 2, the inductor L The other end of 2, the capacitor C 2 and the switching transistor S The source of capacitor 3 forms a Y-type connection; C The other end of 2 is connected to the switching transistor. S The drain connection of 1, the switching transistor S The drain of 3 and the capacitor C One end of 3 is connected; the capacitor C The other end of 3 is used to connect to the negative terminal of the input voltage, and the capacitor C 3. Connect in parallel with the output side to achieve a common ground for input and output; The dual-loop control method includes: Dual-loop control is used to obtain the switching transistor. S Duty cycle D of 1; The output voltage of the inverter is controlled by the duty cycle D; The boost ratio M(D) of the common-ground boost module is: ; This indicates the output voltage of the common-ground boost module; D is the input voltage of the common-ground boost module; D is the switching transistor. S A duty cycle of 1.

2. The dual-loop control method according to claim 1, characterized in that, The switching transistor S 1. Switching transistor S 2 and switching transistors S 3 represents IGBT, MOSFET, or GaN.

3. The dual-loop control method according to claim 1, characterized in that, Dual-loop control is used to obtain the switching transistor. S The duty cycle D of 1 includes: The command value of the output voltage With actual output voltage The difference is used for voltage loop control to obtain the capacitance within one cycle. C 3 current command value ; According to capacitance C 3 current command value Based on the principle of power conservation, the inductance within one cycle is obtained. L 1 current command value ; inductor L 1 current command value With inductance L Actual current value of 1 The difference is used for inductor current loop control to obtain the inductance within one cycle. L Voltage command value of 1 Thus, the switching transistor is obtained. S The duty cycle D is 1.

4. The dual-loop control method according to claim 1, characterized in that, The switching transistor S 2 and the aforementioned switching transistor S The duty cycle of 3 is 1-D, and both are related to the switching transistor. S 1. Complementary conduction.

5. The dual-loop control method according to claim 3, characterized in that, Inductance within one cycle L Voltage command value of 1 With switching transistor S The duty cycle D of 1 satisfies the following: in, The input voltage for a single-phase structure or a single converter; For capacitor C 1. Voltage.

6. The dual-loop control method according to claim 3, characterized in that, According to capacitance C 3 current command value Based on the principle of power conservation, the inductance within one cycle is obtained. L 1 current command value for: in, This refers to the output current value of a single-phase structure or a single converter. This refers to the input voltage of a single-phase structure or a single converter. This refers to the output voltage of a single-phase structure or a single converter.

7. The dual-loop control method according to claim 3, characterized in that, The voltage loop control is either PI control or PIR control; The inductor current loop control is either PI control or PIR control.

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