Three-phase primary energy conversion AC / AC converter and control method thereof

Abstract

The invention provides a three-phase primary energy conversion AC / AC converter and a control method thereof, and relates to the technical field of converters. According to the three-phase one-stage energy conversion AC / AC converter and the control method thereof, one-stage energy conversion is adopted by the converter to achieve AC / AC conversion, a mainstream AC / DC + DC / AC two-stage framework is replaced, fewer devices are used, and high efficiency and low cost are achieved. Meanwhile, the converter can be operated in a boost mode and can also be operated in a buck mode. And the converter is not provided with a bus capacitor, so that the problem of short service life of the bus capacitor is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of converters, and in particular to a three-phase primary energy conversion AC / AC converter and a control method thereof. Background Art

[0002] In the process of power transmission, the stability of voltage determines the quality of power. To ensure the stability and diversity of AC / AC conversion, a common solution is to use back-to-back AC / AC converters, such as Figure 1 As shown, the front stage is a rectifier circuit, which first performs AC / DC conversion, and the back stage adopts an inverter circuit to achieve DC / AC conversion.

[0003] However, the two-stage back-to-back AC / AC converter needs to undergo two-stage energy conversion, AC / DC-DC / AC, and the two-stage energy conversion results in relatively low efficiency. Summary of the invention

[0004] 1. Technical issues to be resolved In view of the deficiencies of the prior art, the present invention provides a three-phase one-stage energy conversion AC / AC converter and a control method thereof, which solves the technical problem of low efficiency of the existing two-stage AC / AC converter.

[0005] (II) Technical solution To achieve the above objectives, the present invention is implemented through the following technical solutions: In a first aspect, the present invention provides a three-phase primary energy conversion AC / AC converter, comprising a first pair of top switch groups, a second pair of top switch groups, a first intermediate inductor, a second intermediate inductor, and three A-phase circuits, B-phase circuits, and C-phase circuits with the same structure; Each phase circuit includes two connection ports, the first connection port is connected to the second connection port via an inductor, an intermediate capacitor and a top switch group, and a power carrier communication capacitor is connected between the first connection port and the second connection port; The first end of the first pair of top switch groups is connected to the common end of the inductor and the middle capacitor of the A phase circuit, and the second end of the first pair of top switch groups is connected to the common end of the inductor and the middle capacitor of the B phase circuit; the first end of the second pair of top switch groups is connected to the second end of the first pair of top switch groups, and the second end of the second pair of top switch groups is connected to the common end of the inductor and the middle capacitor of the C phase circuit; The first end of the first intermediate inductor is connected to the common end of the intermediate capacitor of the A-phase circuit and the top switch group, and the second end of the first intermediate inductor is connected to the common end of the intermediate capacitor of the B-phase circuit and the top switch group; the first end of the second intermediate inductor is connected to the second end of the first intermediate inductor, and the second end of the second intermediate inductor is connected to the common end of the intermediate capacitor of the C-phase circuit and the top switch group; By controlling the duty cycle of the five groups of top switch groups, the voltage of the input AC power supply can be increased or decreased.

[0006] Preferably, it further includes a first filter capacitor and a second filter capacitor. Wherein, the first filter capacitor is connected between the second connection port of the A-phase circuit and the B-phase circuit; The second filter capacitor is connected between the second connection ports of the B-phase circuit and the C-phase circuit.

[0007] Preferably, the first pair of top switch groups, the second pair of top switch groups and the pair of top switch groups in each phase circuit all include two IGBTs with connected emitters.

[0008] Preferably, the first connection port of each phase circuit is respectively connected to the three-phase power grid, and the second connection port of each phase circuit is respectively connected to a load common terminal via the load; or, the second connection port of each phase circuit is respectively connected to the three-phase power grid, and the first connection port of each phase circuit is respectively connected to a load common terminal via the load.

[0009] Preferably, a neutral line is connected between the common terminal of the three-phase power grid and the common terminal of the load.

[0010] In a second aspect, the present invention provides a control method for a three-phase primary energy conversion AC / AC converter, which is used to control the three-phase primary energy conversion AC / AC converter as described in the first aspect, and the control method includes: The switches in the first pair of top switch groups and the second pair of top switch groups are regarded as the first group of switches, and the on-duty ratio is D; the three pairs of top switch groups in the A phase circuit, the B phase circuit and the C phase circuit are regarded as the second group of switches, and the on-duty ratio is 1-D; The voltage at the first connection port of each phase is Vx , x = a , b , c ; The voltage of the second connection port of each phase V1x ; The relationship between the two voltages is: V1x =D / (1-D)* Vx Control the size of the on-duty cycle D to achieve voltage boost or voltage reduction.

[0011] Preferably, when the first connection port of each phase is connected to the input voltage, that is Vx is the input voltage, V1x For the output voltage, when D is set to a fixed value greater than 0.5, boost is achieved, and when D is set to a fixed value less than 0.5, buck is achieved.

[0012] In a third aspect, the present invention provides a three-phase primary energy conversion AC / AC converter, comprising a first pair of top switch groups, a second pair of top switch groups, a first intermediate inductor, a second intermediate inductor, a third intermediate inductor, and three A-phase circuits, B-phase circuits, and C-phase circuits having the same structure; Each phase circuit includes two connection ports, the first connection port is connected to the second connection port via an inductor, an intermediate capacitor and a top switch group, and a power carrier communication capacitor is connected between the first connection port and the second connection port; The first end of the first pair of top switch groups is connected to the common end of the inductor and the middle capacitor of the A phase circuit, and the second end of the first pair of top switch groups is connected to the common end of the inductor and the middle capacitor of the B phase circuit; the first end of the second pair of top switch groups is connected to the second end of the first pair of top switch groups, and the second end of the second pair of top switch groups is connected to the common end of the inductor and the middle capacitor of the C phase circuit; The first end of the first intermediate inductor is connected to the common end of the intermediate capacitor of the A-phase circuit and the top switch group; the first end of the second intermediate inductor is connected to the common end of the intermediate capacitor of the B-phase circuit and the top switch group; the first end of the third intermediate inductor is connected to the common end of the intermediate capacitor of the C-phase circuit and the top switch group; the second end of the first intermediate inductor, the second end of the second intermediate inductor, and the second end of the third intermediate inductor are connected together; By controlling the duty cycle of the five groups of top switch groups, the voltage of the input AC power supply can be increased or decreased.

[0013] In a fourth aspect, the present invention provides a control method for a three-phase primary energy conversion AC / AC converter, which is used to control the three-phase primary energy conversion AC / AC converter as described in the third aspect, and the control method includes: The switches in the first pair of top switch groups and the second pair of top switch groups are regarded as the first group of switches, and the on-duty ratio is D; the three pairs of top switch groups in the A phase circuit, the B phase circuit and the C phase circuit are regarded as the second group of switches, and the on-duty ratio is 1-D; The voltage at the first connection port of each phase is Vx , x = a , b , c ; The voltage of the second connection port of each phase V1x , the relationship between the two voltages is: V1x =D / (1-D)* Vx Control the size of the on-duty cycle D to achieve voltage boost or voltage reduction.

[0014] Preferably, when the first connection port of each phase is connected to the input voltage, that is Vx is the input voltage, V1x For the output voltage, when D is set to a fixed value greater than 0.5, boost is achieved, and when D is set to a fixed value less than 0.5, buck is achieved.

[0015] (III) Beneficial effects The present invention provides a three-phase primary energy conversion AC / AC converter and a control method thereof. Compared with the prior art, it has the following beneficial effects: The present invention proposes a three-phase one-stage energy conversion AC / AC converter and a control method thereof. The converter uses one-stage energy conversion to realize AC / AC conversion, replacing the mainstream, AC / DC+DC / AC two-stage architecture, using fewer devices, achieving high efficiency and low cost. At the same time, the converter can be operated at a boost voltage or a step-down voltage. In addition, the converter has no bus capacitor, and there will be no problem of low bus capacitor life. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A circuit diagram of an existing back-to-back AC / AC converter; Figure 2 is a circuit diagram of an existing cascade Buck-Boost converter; Figure 3 The circuit diagram of the existing phase-controllable three-phase Buck type AC / AC converter; Figure 4 This is a structural diagram of a three-phase primary energy conversion AC / AC converter in Example 1; Figure 5 for Figure 4 One of the circuit diagrams of the shown architecture diagram; Figure 6 The circuit diagram of the AC / AC converter with three-phase primary energy conversion with filter capacitor in Example 1; Figure 7 The circuit diagram of the AC / AC converter for three-phase primary energy conversion with filter capacitor and neutral line in Example 1; Figure 8 The circuit diagram of the AC / AC converter for three-phase primary energy conversion with a neutral line in Example 1; Fig. 9 for Figure 8Schematic diagram of working mode 1 and working mode 3 of the circuit diagram shown; Fig.10 for Figure 8 A schematic diagram of the working mode 2 of the circuit diagram shown; Fig.11 for Figure 8 A schematic diagram of the working mode 4 of the circuit diagram shown; Fig.12 This is a circuit diagram of the AC / AC converter for three-phase primary energy conversion in Example 2. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] It should be noted that, for the convenience of description, the switch IGBT is used to represent the controllable (on and off) switch tube in the embodiment of the present invention, but the switch tube in the present invention is not limited to IGBT. Take IGBT as an example for explanation. The first end of the IGBT refers to the collector, the second end is the emitter, and the control end refers to the gate. A driving control signal is applied to the control end of each switch tube in the embodiment of the present invention. For the sake of brevity, it will not be repeated later. The power switch tube in the embodiment of the present invention can also be implemented by other controllable switch tube devices other than IGBT, such as MOSFET. At the same time, in order to ensure the normal operation of each switch device in the embodiment of the present invention, a freewheeling diode needs to be connected in parallel to each switch device. The parallel connection direction of the freewheeling diode is related to the type of the switch device. The technician can set it according to the type of the switch device, which is not limited here. If not specified, the switch device defaults to including a freewheeling diode, which will be pointed out in this embodiment in special cases.

[0020] The embodiment of the present application solves the technical problem of low efficiency of the existing two-stage AC / AC converter by providing a three-phase one-stage energy conversion AC / AC converter and a control method thereof, and adopts one-stage energy conversion to realize AC / AC conversion and improve efficiency.

[0021] The technical solution in the embodiment of the present application is to solve the above technical problems, and the overall idea is as follows: The existing AC / AC converters mainly include back-to-back AC / AC converters, cascaded Buck-Boost converters and phase-controlled three-phase Buck AC / AC converters. Figure 1As shown, the front stage is a rectifier circuit, and the back stage uses an inverter circuit to achieve DC / AC conversion.

[0022] The cascade Buck-Boost converter takes a single-phase two-level cascade converter as an example. Figure 2 As shown in the figure, the circuit is composed of two cascaded converters, Buck type and Boost type. According to the comparison of the input voltage and output voltage amplitude, it has the functions of boosting, filtering and bucking at the same time. When the front-stage Buck circuit works and the rear-stage Boost circuit does not work, the circuit works in Buck mode; when the front-stage Buck circuit does not work and the rear-stage Boost circuit works, the circuit works in Boost mode; when the switch tubes S1 and S4 are turned on, S2 and S3 are turned off, and the input voltage fluctuates slightly, the circuit works in filtering mode.

[0023] Phase controllable three-phase Buck type AC / AC converter such as Figure 3 As shown in the figure, it is mainly composed of 3 single-phase Buck AC conversion units and a three-phase output filter, in which the filter capacitors are connected in a triangle connection. The single-phase analysis includes: four switch tubes, and the three-phase circuit is 12 switch tubes, and each circuit requires 2 capacitors and 2 inductors. The circuit is composed of 3 single-phase Buck AC units and a three-phase output filter. The filter capacitors are connected in a triangle connection, so that the 3rd harmonic voltages in the 3 single-phase Buck AC units cancel each other, and then ensure that the 3rd harmonic current does not flow through the output filter inductor, and a phase-controllable sinusoidal output line voltage is obtained at the output end.

[0024] However, if Figure 1 The two-stage back-to-back ACAC converter shown in the figure needs to undergo two-stage energy conversion, which has low efficiency and uses many components, resulting in high cost. Figure 2 The cascaded Buck-Boost converter shown in FIG. 1 has many components and high cost when used in three-phase applications. Figure 3 The phase-controllable three-phase Buck-type AC / AC converter topology shown can only achieve voltage reduction, and uses many devices and is costly.

[0025] In order to overcome the above problems, the embodiment of the present invention proposes a three-phase one-stage energy conversion AC / AC converter and a control method thereof. The converter uses one-stage energy conversion to realize AC / AC conversion, replacing the mainstream, AC / DC+DC / AC two-stage architecture, using fewer devices, achieving high efficiency and low cost. At the same time, the converter can be operated at a boost voltage or a step-down voltage. In addition, the converter uses a top switch to construct a bidirectional energy path, which can realize bidirectional operation.

[0026] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0027] Embodiment 1: This embodiment provides a three-phase primary energy conversion AC / AC converter, such as Figure 4 As shown, the converter includes a first pair of top switch groups, a second pair of top switch groups, a first intermediate inductor, a second intermediate inductor, and three A-phase circuits, B-phase circuits, and C-phase circuits with the same structure; Each phase circuit includes two connection ports, the first connection port is connected to the second connection port via an inductor, an intermediate capacitor and a top switch group, and a power carrier communication capacitor is connected between the first connection port and the second connection port; The first end of the first pair of top switch groups is connected to the common end of the inductor and the middle capacitor of the A phase circuit, and the second end of the first pair of top switch groups is connected to the common end of the inductor and the middle capacitor of the B phase circuit; the first end of the second pair of top switch groups is connected to the second end of the first pair of top switch groups, and the second end of the second pair of top switch groups is connected to the common end of the inductor and the middle capacitor of the C phase circuit; The first end of the first intermediate inductor is connected to the common end of the intermediate capacitor of the A-phase circuit and the top switch group, and the second end of the first intermediate inductor is connected to the common end of the intermediate capacitor of the B-phase circuit and the top switch group; the first end of the second intermediate inductor is connected to the second end of the first intermediate inductor, and the second end of the second intermediate inductor is connected to the common end of the intermediate capacitor of the C-phase circuit and the top switch group; By controlling the duty cycle of the five groups of top switch groups, the voltage of the input AC power supply can be increased or decreased.

[0028] It should be noted that in Figure 4 In the embodiment, the inductors in the three-phase circuits A, B, and C are La, Lb, and Lc respectively, the intermediate capacitors in the three-phase circuits A, B, and C are Ca, Cb, and Cc respectively, and the power carrier communication capacitors in the three-phase circuits A, B, and C are Ca2, Cb2, and Cc2. The first intermediate inductor Lab and the second intermediate inductor Lbc. Of course, in the specific implementation process, the intermediate inductor, the intermediate capacitor, etc. can be an inductor group, a capacitor group, etc. composed of multiple devices. Figure 4 In the embodiment of the present invention, a capacitor, an inductor, etc. are taken as an example. Meanwhile, in the embodiment of the present invention, ABC only represents the sequence number of the three-phase circuit, but does not correspond to the phase sequence of the three-phase circuit of the power grid.

[0029] It should be noted that in Figure 5 In the embodiment, the first top switch group, the second top switch group, and the top switch groups in the A, B, and C three-phase circuits all use two top-to-top IGBTs. In the specific implementation process, other forms of switch tubes, such as MOSFET, can also be used.

[0030] It should be noted that, in the embodiment of the present invention, the three-phase primary energy conversion AC / AC converter can realize bidirectional operation, that is, the objects connected to the two connection ports of each phase circuit can be swapped, and the two sides can be respectively connected to the three-phase AC power grid or the load (the load can also be replaced with a charging power supply).

[0031] like Figure 6 As shown, in the specific implementation process, in order to achieve better filtering (the capacitors Ca2, Cb2, and Cc2 of the power carrier communication also have a filtering effect), a first filter capacitor C1 is connected between the second connection ports of the A-phase circuit and the B-phase circuit, and a second filter capacitor C2 is connected between the second connection ports of the B-phase circuit and the C-phase circuit.

[0032] like Figure 7 As shown, in a specific implementation process, a neutral line is connected to the common end of the three-phase input power supply and the common end of the three-phase output, which is suitable for application in a three-phase four-wire system to provide a flow path for zero-sequence current.

[0033] It should be noted that the converter can also be connected with a neutral line but without a filter capacitor, such as Figure 8 As shown, the first connection port of the three-phase circuit A, B, C of the converter is connected to the three-phase power grid, and the second connection port of the three-phase circuit A, B, C is connected to a resistive load respectively.

[0034] Below Figure 8 The circuit shown performs modal analysis on the converter. Since the three-phase voltage is periodic, the mode of this topology also has a periodic change rule. Next, we will mainly analyze the cases where the A and B phase voltages are greater than zero, the C phase grid voltage is less than zero, and the A phase voltage is greater than zero, and the B and C phase grid voltages are less than zero (other modes can be obtained by analogy): When the voltage of phases A and B is greater than zero and the voltage of phase C is less than zero: Working mode 1: Fig. 9 As shown, the switch tubes T1, T2, T3 and T4 form the first group of switches that are turned on (switch tubes T1 and T3 are forward-conducting, and the anti-parallel diodes of T2 and T4 are turned on), and the switch tubes T5, T6, T7, T8, T9 and T10 form the second group of switches that are turned off. In this mode, the power supply voltage charges the input inductors La, Lb, and Lc, and the intermediate capacitors Ca, Cb, and Cc charge the output inductors Lab and Lbc through the switches. The current direction of the power carrier communication is related to the phase voltage difference of the connection at both ends of itself, and the switching mode will not have an impact, so it will not be repeated.

[0035] Working mode 2: Fig.10As shown, the switch tubes T1, T2, T3 and T4 form a first group of switches that are turned off, and the switch tubes T5, T6, T7, T8, T9 and T10 form a second switch that is turned on (the switch tubes T5, T7 and T10 are forward-conducted, and the anti-parallel diodes of T6, T8 and T9 are turned on). In this mode, the input inductors La, Lb, Lc and the output inductors Lab, Lbc are freewheeling through the second group of switch tubes to release the inductor energy to the load.

[0036] When the voltage of phase A is greater than zero and the voltage of phase B and phase C is less than zero: Working mode 3: The switch tubes T1, T2, T3 and T4 form the first group of switches that are turned on (switch tubes T1 and T3 are forward-conducting, and the anti-parallel diodes of T2 and T4 are turned on), and the switch tubes T5, T6, T7, T8, T9 and T10 form the second group of switches that are turned off. In this mode, the power supply voltage charges the input inductors La, Lb, and Lc, and the intermediate capacitors Ca, Cb, and Cc charge the output inductors Lab and Lbc through the switches. It should be noted that the corresponding circuit diagram of this mode is the same as the circuit diagram of working mode 1. Figure 1 To, such as Fig. 9 shown.

[0037] Working mode 4: Fig.11 As shown, the switch tubes T1, T2, T3 and T4 form a first group of switches that are turned off, and the switch tubes T5, T6, T7, T8, T9 and T10 form a second switch that is turned on (the switch tubes T5, T8 and T10 are forward-conducted, and the anti-parallel diodes of T6, T7 and T9 are turned on). In this mode, the input inductors La, Lb, Lc and the output inductors Lab, Lbc are freewheeling through the second group of switch tubes to release the inductor energy to the load.

[0038] Embodiment 2: This embodiment provides a three-phase primary energy conversion AC / AC converter, such as Fig.12 As shown (in Fig.12 In the embodiment, the top switch group uses two top IGBTs), the converter includes a first top switch group, a second top switch group, a first intermediate inductor, a second intermediate inductor, a third intermediate inductor, and three A-phase circuits, B-phase circuits, and C-phase circuits with the same structure; Each phase circuit includes two connection ports, the first connection port is connected to the second connection port via an inductor, an intermediate capacitor and a top switch group, and a power carrier communication capacitor is connected between the first connection port and the second connection port; The first end of the first pair of top switch groups is connected to the common end of the inductor and the middle capacitor of the A phase circuit, and the second end of the first pair of top switch groups is connected to the common end of the inductor and the middle capacitor of the B phase circuit; the first end of the second pair of top switch groups is connected to the second end of the first pair of top switch groups, and the second end of the second pair of top switch groups is connected to the common end of the inductor and the middle capacitor of the C phase circuit; The first end of the first intermediate inductor is connected to the common end of the intermediate capacitor of the A-phase circuit and the top switch group; the first end of the second intermediate inductor is connected to the common end of the intermediate capacitor of the B-phase circuit and the top switch group; the first end of the third intermediate inductor is connected to the common end of the intermediate capacitor of the C-phase circuit and the top switch group; the second end of the first intermediate inductor, the second end of the second intermediate inductor, and the second end of the third intermediate inductor are connected together; By controlling the duty cycle of the five groups of top switch groups, the voltage of the input AC power supply can be increased or decreased.

[0039] Embodiment 3: An embodiment of the present invention provides a control method for a three-phase primary energy conversion AC / AC converter, the method comprising: The mathematical relationship between input and output voltage is given below: If the switch tubes T1, T2, T3 and T4 form the first group of switches with a duty cycle of D, the switch tubes T5, T6, T7, T8, T9 and T10 form the second group of switches with a duty cycle of 1-D (Note: According to the partial mode given by the circuit, when each switch group is working, one switch is always forward-conducting and the other switch is anti-parallel diode-conducting, which is determined by the drive signal and the voltage of the switch group. Therefore, the duty cycle in the control method refers to the duty cycle of the switch group). The first connection port of each phase is connected to the input voltage Vx For example, the output voltage of each phase is V1x =D / (1-D)* Vx ( x = a , b , c ), it can be concluded that the output voltage of each phase is only related to the input voltage of the corresponding phase and the on-duty cycle of the switch group. When the switch tubes T1, T2, T3 and T4 form the first group of switches with an on-duty cycle D>0.5, a voltage step-up change can be achieved; when the switch tubes T1, T2, T3 and T4 form the first group of switches with an on-duty cycle D<0.5, a voltage step-down change can be achieved.

[0040] The input voltage is AC voltage, according to the output voltage V1x =D / (1-D)* Vx ( x = a , b , c), in order to achieve AC / AC conversion, only the duty cycle needs to be fixed. When the voltage is required to be increased, the duty cycle D>0.5 takes a fixed value; when the voltage is required to be reduced, the duty cycle D<0.5 takes a fixed value; Due to the on-off characteristics of the fully controllable device, the first switch group shares a drive signal, the second switch group shares a drive signal, and the duty cycle of the target output voltage is fixed, so AC / AC conversion can be achieved (since the first switch group and the second switch group are driven complementary, a switch dead zone needs to be added in actual application) In summary, compared with the prior art, the present invention has the following beneficial effects: 1. The embodiment of the present invention proposes a three-phase one-stage energy conversion AC / AC converter and a control method thereof. The converter uses one-stage energy conversion to achieve AC / AC conversion, replacing the mainstream, AC / DC+DC / AC two-stage architecture, using fewer devices, achieving high efficiency and low cost. At the same time, the converter can operate in boost or buck mode.

[0041] 2. The three-phase one-stage energy conversion AC / AC converter of the embodiment of the present invention is coupled in circuit form. After mathematical analysis, the output voltage of each phase is only related to the input voltage of the corresponding phase. Therefore, the three-phase circuit is decoupled in mathematical relationship, and therefore relatively easy to control.

[0042] 3. The embodiment of the present invention uses top switches to construct a bidirectional energy path, and the proposed three-phase one-stage energy conversion AC / AC converter can achieve bidirectional operation.

[0043] 4. The embodiment of the present invention does not use bus capacitors, thus avoiding the problem of short life of bus capacitors in the two-stage solution.

[0044] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0045] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A three-phase primary energy conversion AC / AC converter, characterized in that: It includes a first pair of top switch groups, a second pair of top switch groups, a first intermediate inductor, a second intermediate inductor, and three A-phase circuits, B-phase circuits, and C-phase circuits with the same structure; Each phase circuit includes two connection ports, the first connection port is connected to the second connection port via an inductor, an intermediate capacitor and a top switch group, and a power carrier communication capacitor is connected between the first connection port and the second connection port; The first end of the first pair of top switch groups is connected to the common end of the inductor and the middle capacitor of the A phase circuit, and the second end of the first pair of top switch groups is connected to the common end of the inductor and the middle capacitor of the B phase circuit; the first end of the second pair of top switch groups is connected to the second end of the first pair of top switch groups, and the second end of the second pair of top switch groups is connected to the common end of the inductor and the middle capacitor of the C phase circuit; The first end of the first intermediate inductor is connected to the common end of the intermediate capacitor of the A-phase circuit and the top switch group, and the second end of the first intermediate inductor is connected to the common end of the intermediate capacitor of the B-phase circuit and the top switch group; the first end of the second intermediate inductor is connected to the second end of the first intermediate inductor, and the second end of the second intermediate inductor is connected to the common end of the intermediate capacitor of the C-phase circuit and the top switch group; By controlling the duty cycle of the five groups of top switch groups, the voltage of the input AC power supply can be increased or decreased.

2. The three-phase primary energy conversion AC / AC converter according to claim 1, characterized in that: Also includes a first filter capacitor and a second filter capacitor, Wherein, the first filter capacitor is connected between the second connection port of the A-phase circuit and the B-phase circuit; The second filter capacitor is connected between the second connection ports of the B-phase circuit and the C-phase circuit.

3. The three-phase primary energy conversion AC / AC converter according to claim 1, characterized in that: The first pair of top switch groups, the second pair of top switch groups, and the pair of top switch groups in each phase circuit all include two IGBTs with connected emitters.

4. The three-phase primary energy conversion AC / AC converter according to claim 1, characterized in that: The first connection port of each phase circuit is connected to the three-phase power grid, and the second connection port of each phase circuit is connected to a load common terminal via the load; or, the second connection port of each phase circuit is connected to the three-phase power grid, and the first connection port of each phase circuit is connected to a load common terminal via the load.

5. The three-phase primary energy conversion AC / AC converter according to claim 1, characterized in that: A neutral line is connected between the common end of the three-phase power grid and the common end of the load.

6. A control method for a three-phase primary energy conversion AC / AC converter, characterized in that: Used to control the AC / AC converter for three-phase primary energy conversion as claimed in any one of claims 1 to 5, the control method comprising: The switches in the first pair of top switch groups and the second pair of top switch groups are regarded as the first group of switches, and the on-duty ratio is D; the three pairs of top switch groups in the A phase circuit, the B phase circuit and the C phase circuit are regarded as the second group of switches, and the on-duty ratio is 1-D; The voltage at the first connection port of each phase is Vx , x = a , b , c ; The voltage of the second connection port of each phase V1x ; The relationship between the two voltages is: V1x =D / (1-D)* Vx Control the size of the on-duty cycle D to achieve voltage boost or voltage reduction.

7. The control method of the AC / AC converter for three-phase primary energy conversion according to claim 6, characterized in that: When the first connection port of each phase is connected to the input voltage, that is Vx is the input voltage, V1x For the output voltage, when D is set to a fixed value greater than 0.5, boost is achieved, and when D is set to a fixed value less than 0.5, buck is achieved.

8. A three-phase primary energy conversion AC / AC converter, characterized in that: It includes a first pair of top switch groups, a second pair of top switch groups, a first intermediate inductor, a second intermediate inductor, a third intermediate inductor, and three A-phase circuits, B-phase circuits, and C-phase circuits with the same structure; Each phase circuit includes two connection ports, the first connection port is connected to the second connection port via an inductor, an intermediate capacitor and a top switch group, and a power carrier communication capacitor is connected between the first connection port and the second connection port; The first end of the first pair of top switch groups is connected to the common end of the inductor and the middle capacitor of the A phase circuit, and the second end of the first pair of top switch groups is connected to the common end of the inductor and the middle capacitor of the B phase circuit; the first end of the second pair of top switch groups is connected to the second end of the first pair of top switch groups, and the second end of the second pair of top switch groups is connected to the common end of the inductor and the middle capacitor of the C phase circuit; The first end of the first intermediate inductor is connected to the common end of the intermediate capacitor of the A-phase circuit and the top switch group; the first end of the second intermediate inductor is connected to the common end of the intermediate capacitor of the B-phase circuit and the top switch group; the first end of the third intermediate inductor is connected to the common end of the intermediate capacitor of the C-phase circuit and the top switch group; the second end of the first intermediate inductor, the second end of the second intermediate inductor, and the second end of the third intermediate inductor are connected together; By controlling the duty cycle of the five groups of top switch groups, the voltage of the input AC power supply can be increased or decreased.

9. A control method for a three-phase primary energy conversion AC / AC converter, characterized in that: For controlling the AC / AC converter for three-phase primary energy conversion as claimed in claim 8, the control method comprises: The switches in the first pair of top switch groups and the second pair of top switch groups are regarded as the first group of switches, and the on-duty ratio is D; the three pairs of top switch groups in the A phase circuit, the B phase circuit and the C phase circuit are regarded as the second group of switches, and the on-duty ratio is 1-D; The voltage at the first connection port of each phase is Vx , x = a , b , c ; The voltage of the second connection port of each phase V1x ; The relationship between the two voltages is: V1x =D / (1-D)* Vx Control the size of the on-duty cycle D to achieve voltage boost or voltage reduction.

10. The control method of the AC / AC converter for three-phase primary energy conversion according to claim 9, characterized in that: When the first connection port of each phase is connected to the input voltage, that is Vx is the input voltage, V1x For the output voltage, when D is set to a fixed value greater than 0.5, boost is achieved, and when D is set to a fixed value less than 0.5, buck is achieved.

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