Alternating current to alternating current conversion circuit and motor device

Abstract

The invention discloses an AC-to-AC conversion circuit and a motor device, the AC-to-AC conversion circuit comprises a current source input module and a conversion module, the current source input module is connected with the conversion module and is used for providing an inductive current, and the conversion module is used for providing an output current for a load based on the inductive current; the current source input module comprises a bidirectional switch and an output inductor, and the bidirectional switch is used for controlling the magnitude of inductive current output by the output inductor; the conversion module comprises three phases of bridge arms which are respectively a first phase bridge arm, a second phase bridge arm and a third phase bridge arm, and each phase bridge arm comprises two bidirectional switches which are connected in series; and the current source input module and the conversion module are respectively configured to be connected with the control module, so that the control module controls the on and off of all the bidirectional switches, thereby realizing the voltage transformation and frequency conversion control of the AC-to-AC conversion circuit. According to the AC-to-AC conversion circuit, intermediate links of DC conversion are reduced, and the efficiency of the conversion circuit can be effectively improved.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, specifically to an AC-to-AC conversion circuit and motor device. Background Technology

[0002] With the booming development of the power electronics industry, power electronic devices are constantly being updated and upgraded, making it possible to improve the efficiency and power density of converter circuits. Single-phase / three-phase AC-to-AC converters, as bridges for AC-AC power conversion, are widely used in household appliances and industrial production. Traditional single-phase / three-phase AC-to-AC converters mostly adopt a two-stage structure, requiring power to undergo two stages of conversion: AC to DC and DC to AC, resulting in low efficiency. Therefore, research on single-phase / three-phase AC-to-AC converter circuits is of great significance.

[0003] Furthermore, due to the limitations of the number and size of components in traditional circuits, the size of traditional topology circuits is difficult to further reduce, thus limiting the improvement of power density. How to improve power density and save space occupied by the converter is a technical problem that urgently needs to be solved. Summary of the Invention

[0004] This application proposes an AC-to-AC converter circuit and motor device, which aims to solve the above-mentioned problems.

[0005] To solve the above-mentioned technical problems, one technical solution adopted in this application is: providing an AC-to-AC conversion circuit, which includes a current source input module and a conversion module. The current source input module is connected to the conversion module and is used to provide inductor current. The conversion module is used to provide output current to the load based on the inductor current. The current source input module includes a bidirectional switch and an output inductor. The bidirectional switch is used to control the magnitude of the inductor current output by the output inductor. The conversion module includes three phase arms, namely a first phase arm, a second phase arm, and a third phase arm. Each phase arm includes two bidirectional switches connected in series. The current source input module and the conversion module are respectively configured to be connected to a control module so that the control module controls the on and off of all bidirectional switches, thereby realizing the voltage and frequency conversion control of the AC-to-AC conversion circuit.

[0006] The current source input module includes an AC power supply, a seventh bidirectional switch, and an output inductor. The first end of the AC power supply is connected to the first path end of the seventh bidirectional switch, the second path end of the seventh bidirectional switch is connected to the first end of the output inductor, the second end of the output inductor is connected to the second end of the AC power supply, and the connection point between the second path end of the seventh bidirectional switch and the first end of the output inductor serves as the output end.

[0007] The current source input module also includes a filter capacitor and a filter inductor. The first end of the filter inductor is connected to the first end of the AC power supply. The second end of the filter inductor is connected to the first end of the seventh bidirectional switch and the first end of the filter capacitor. The second end of the filter capacitor is connected to the second end of the AC power supply.

[0008] When the seventh bidirectional switch is in the ON state, and the converter module outputs a zero vector current, the AC power supply charges the output inductor, and the inductor current increases. When the seventh bidirectional switch is in the OFF state, and the converter module outputs a zero vector current, the output inductor freewheels through the bridge arm of the converter module, and the inductor current remains unchanged. When the seventh bidirectional switch is in the OFF state, and the converter module outputs a valid vector current, the output inductor discharges to the load, and the inductor current decreases.

[0009] The output current includes a first output current, a second output current, and a third output current. The first phase bridge arm includes a first bidirectional switch and a second bidirectional switch connected in series. The second phase bridge arm includes a third bidirectional switch and a fourth bidirectional switch connected in series. The third phase bridge arm includes a fifth bidirectional switch and a sixth bidirectional switch connected in series. The first path terminal of the first bidirectional switch, the first path terminal of the third bidirectional switch, and the first path terminal of the fifth bidirectional switch are all connected to the second terminal of the output inductor. The second path terminals of the second bidirectional switch, the second path terminals of the fourth bidirectional switch, and the second path terminals of the sixth bidirectional switch are all connected to the second terminal of the AC power supply. The connection points of the second path terminals of the first, third, and sixth bidirectional switches serve as the output terminals of the first, second, and third phase bridge arms, respectively, to output the first, second, and third output currents. At any given time, only one of the first, third, and fifth bidirectional switches, and only one of the second, fourth, and sixth bidirectional switches is conducting, forming a unique current path for the conversion module.

[0010] Specifically, when the first and second bidirectional switches are in the ON state, the third and fourth bidirectional switches are in the ON state, or the fifth and sixth bidirectional switches are in the ON state, the conversion module outputs a zero current vector; when the first and sixth bidirectional switches are in the ON state, the third and sixth bidirectional switches are in the ON state, the third and second bidirectional switches are in the ON state, the fifth and second bidirectional switches are in the ON state, the fifth and fourth bidirectional switches are in the ON state, or the first and fourth bidirectional switches are in the ON state, the conversion module outputs a valid current vector.

[0011] The AC-to-AC converter circuit also includes a filter and freewheeling module, which is connected to the connection between the converter module and the load and is used to filter and freewheel the output current.

[0012] The filter freewheeling module includes a first capacitor, a second capacitor, and a third capacitor. The first terminal of the first capacitor, the first terminal of the second capacitor, and the first terminal of the third capacitor are respectively connected to the output terminals of the first phase bridge arm, the second phase bridge arm, and the third phase bridge arm. The second terminals of the first capacitor, the second terminal of the second capacitor, and the second terminal of the third capacitor are connected together.

[0013] The inductor current of the output inductor, the input current of the AC power supply, and the voltage of the AC power supply are configured as in-phase sine waves.

[0014] Among them, bidirectional switches include bidirectional gallium nitride switches, bidirectional insulated gate bipolar transistor switches, or bidirectional metal-oxide-semiconductor field-effect transistor switches.

[0015] The bidirectional switch can be configured as two unidirectional switches connected in series. When two unidirectional switches are connected in series, their drains or sources are connected.

[0016] To solve the above-mentioned technical problems, another technical solution adopted in this application is: to provide a motor device, which includes an AC to AC conversion circuit and a control module as described above. The control module is connected to the current source input module and the conversion module respectively, and is used to control the on and off of all bidirectional switches so that the AC to AC conversion circuit can realize voltage and frequency conversion control.

[0017] The control module is also used to sample the input current of the current source input module and the output current of the conversion module, and to perform closed-loop control on the input current and output current based on the output requirements to obtain the instantaneous modulation ratio of each phase arm. The instantaneous modulation ratio is used to adjust the amplitude and frequency of the output current of each phase arm so that the AC to AC conversion circuit can achieve variable voltage and variable frequency control.

[0018] The beneficial effects of this application are as follows: Unlike existing technologies, the current source input module and conversion module of this application are connected to provide inductor current. The current source input module is used to provide inductor current, and the conversion module is used to provide output current to the load based on the inductor current. The current source input module includes a bidirectional switch and an output inductor. The bidirectional switch is used to control the magnitude of the inductor current output by the output inductor. The conversion module includes three phase arms: a first phase arm, a second phase arm, and a third phase arm. Each phase arm includes two bidirectional switches connected in series. The current source input module and conversion module are respectively configured to be connected to a control module, so that the control module controls the on and off states of all bidirectional switches, thereby realizing the voltage and frequency conversion control of the AC-to-AC conversion circuit. Through the above method, the AC-to-AC conversion circuit of this application reduces intermediate steps in DC-DC conversion, effectively improving the efficiency of the converter circuit, while reducing the converter circuit's dependence on capacitor capacity and inductor inductance, thereby reducing the size of the converter circuit and improving its power density and reliability. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with this application and, together with the specification, serve to explain the technical solutions of this application.

[0020] Figure 1 This is a schematic diagram of the circuit structure of an embodiment of the AC-to-AC converter circuit provided in this application;

[0021] Figure 2 This is a schematic diagram of the circuit structure of another embodiment of the AC-to-AC converter circuit provided in this application;

[0022] Figure 3 This is a schematic diagram of an embodiment of the current space vector provided in this application;

[0023] Figure 4 This is a schematic diagram of the structure of an embodiment of the motor device provided in this application;

[0024] Figure 5 This is a schematic diagram of the algorithm flow of an embodiment of the control module of this application. Detailed Implementation

[0025] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0027] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0028] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0029] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0030] With the booming development of the power electronics industry, power electronic devices are constantly being updated and upgraded, making it possible to improve the efficiency and power density of converter circuits. Single-phase / three-phase AC-to-AC converters, as bridges for AC-AC power conversion, are widely used in household appliances and industrial production. Traditional single-phase / three-phase AC-to-AC converters mostly adopt a two-stage structure, requiring power to undergo two stages of conversion: AC to DC and DC to AC, resulting in low efficiency. Therefore, research on single-phase / three-phase AC-to-AC converter circuits is of great significance.

[0031] Furthermore, due to the limitations of the number and size of components in traditional circuits, the size of traditional topology circuits is difficult to further reduce, thus limiting the improvement of power density. How to improve power density and save space occupied by the converter is a technical problem that urgently needs to be solved.

[0032] To address the aforementioned problems, this application first proposes an AC-to-AC conversion circuit, please refer to [link to relevant documentation]. Figure 1 , Figure 1 This is a schematic diagram of the circuit structure of an embodiment of the AC-to-AC converter circuit provided in this application. Figure 1 As shown, the AC to AC conversion circuit 100 of this embodiment includes a current source input module 10 and a conversion module 20.

[0033] The current source input module 10 is connected to the conversion module 20 and is used to provide the inductor current i. ac The conversion module 20 is used for conversion based on inductor current i ac Provides output current to the load; the current source input module 10 includes a bidirectional switch and an output inductor L. ac A two-way switch is used to control the output inductor L. ac Output inductor current i ac The size; the conversion module 20 includes three phase bridge arms, namely the first phase bridge arm, the second phase bridge arm and the third phase bridge arm, each phase bridge arm includes two bidirectional switches connected in series; the current source input module 10 and the conversion module 20 are respectively configured to be connected to the control module so that the control module controls the conduction and cutoff of all bidirectional switches, thereby realizing the voltage and frequency conversion control of the AC to AC conversion circuit 100.

[0034] In this embodiment, the current source input module 10 includes only one bidirectional switch, which is connected to the output inductor L. ac Series configuration, and output inductor L ac Output inductor current i ac The conversion module 20 is directly connected to the current source input module 10, based on the inductor current i. ac The AC-to-AC converter 100 provides output current to the load. During operation, the control module can sample the signals on the input and output sides of the AC-to-AC converter 100, and perform closed-loop control based on the input and output signals and output requirements to generate corresponding modulation signals. It also generates drive signals based on PWM modulation, hysteresis control, and other methods to control the conduction and cutoff of all bidirectional switches in the current source input module 10 and the conversion module 20, thereby enabling the AC-to-AC converter 100 to achieve the purpose of voltage and frequency conversion.

[0035] In this embodiment, all switches in the current source input module 10 and the conversion module 20 are bidirectional switches. The bidirectional switches can conduct positive and negative bidirectional currents in the on state and block bidirectional currents in the off state.

[0036] Unlike existing technologies, the AC-to-AC converter circuit 100 of this application includes a current source input module 10 and a conversion module 20. The current source input module 10 is connected to the conversion module 20 and is used to provide inductor current i. ac The conversion module 20 is used for conversion based on inductor current i ac Provides output current to the load; the current source input module 10 includes a bidirectional switch and an output inductor L. ac A two-way switch is used to control the output inductor L. ac Output inductor current i ac The size of the converter module 20 is as follows: The converter module 20 includes three phase arms, namely the first phase arm, the second phase arm, and the third phase arm. Each phase arm includes two bidirectional switches connected in series. The current source input module 10 and the converter module 20 are respectively configured to be connected to the control module, so that the control module controls the on and off of all bidirectional switches, thereby realizing the voltage and frequency conversion control of the AC-to-AC converter circuit 100. Through the above method, the AC-to-AC converter circuit 100 of this application reduces the intermediate links in DC-DC conversion, effectively improving the efficiency of the converter circuit, while reducing the dependence of the converter circuit on capacitor capacity and inductor inductance, thereby reducing the size of the converter circuit and improving the power density and reliability of the converter circuit.

[0037] Optionally, such as Figure 1 As shown, in this embodiment, the current source input module 10 includes an AC power supply e in The seventh bidirectional switch S7 and output inductor L ac AC power e in The first terminal a is connected to the first pass terminal of the seventh bidirectional switch S7, and the second pass terminal of the seventh bidirectional switch S7 is connected to the output inductor L. ac The first terminal is connected to the output inductor L. ac The second terminal is connected to the AC power supply e in The second terminal b is connected, and the second path terminal of the seventh bidirectional switch S7 is connected to the output inductor L. ac The connection point at the first end serves as the output end.

[0038] In this embodiment, the current source input module 10 is equipped with only one bidirectional switch. Compared to using multiple switches, this embodiment uses one bidirectional switch to control the inductor current i. ac It can reduce costs.

[0039] Furthermore, aside from filtering factors, in this embodiment, the current source input module 10 does not require a capacitor; only the output inductor L needs to be configured. ac Therefore, the current source input module 10 in this embodiment can guarantee the inductor current i ac No sudden change, output inductance L acEnergy storage suppresses current fluctuations.

[0040] Optionally, please refer to Figure 2 , Figure 2 This is a schematic diagram of the circuit structure of another embodiment of the AC-to-AC converter circuit provided in this application. Figure 2 As shown, the current source input module 10 in this embodiment also includes a filter capacitor C. EMI Filter inductor L EMI Filter inductor L EMI The first terminal is connected to the AC power source e in The first terminal a is connected to the filter inductor L. EMI The second terminal is respectively the first terminal of the seventh bidirectional switch S7 and the filter capacitor C. EMI The first terminal is connected to the filter capacitor C. EMI The second terminal is connected to the AC power supply e in The second end b is connected.

[0041] In this embodiment, the filter capacitor C EMI and filter inductor L EMI Used to filter out electromagnetic interference in the current source input module 10.

[0042] Optionally, based on the above embodiments, in this embodiment, when the seventh bidirectional switch S7 is in the ON state, and the conversion module 20 outputs a zero vector current, the AC power supply e in For output inductor L ac Charging, inductor current i ac Rise; when the seventh bidirectional switch S7 is in the off state, and the conversion module 20 outputs a zero vector current, the output inductor L ac Through the bridge arm freewheeling of the conversion module 20, the inductor current i ac Unchanged; when the seventh bidirectional switch S7 is in the off state, and the conversion module 20 outputs the effective vector of the current, the output inductor L ac Discharging the load, the inductor current i ac reduce.

[0043] In this embodiment, when the seventh bidirectional switch S7 is in the ON state and the conversion module 20 outputs a zero current vector, the AC power supply e in The current flows through the filter inductor L EMI The seventh bidirectional switch S7 leads to the output inductor L. ac For output inductance L ac Charging is initiated. When the seventh bidirectional switch S7 is in the off state, and the conversion module 20 outputs a zero vector current, the output inductor L... ac Inductor current i ac The inductor current i flows through a loop formed by itself and the bridge arm directly connected to the conversion module 20.ac The value remains unchanged for the time being. When the seventh bidirectional switch S7 is in the off state, and the conversion module 20 outputs the effective vector of the current, the output inductance L... ac Inductor current i ac The converter module 20 then provides output current to the load, discharging the load. Therefore, the inductor current i ac It gets smaller.

[0044] Optionally, based on the above embodiments, such as Figure 1 and Figure 2 As shown, in this embodiment, the output current includes the first output current i U Second output current i V and the third output current i W The first phase bridge arm includes a first bidirectional switch S1 and a second bidirectional switch S2 connected in series; the second phase bridge arm includes a third bidirectional switch S3 and a fourth bidirectional switch S4 connected in series; and the third phase bridge arm includes a fifth bidirectional switch S5 and a sixth bidirectional switch S6 connected in series. The first pass terminal of the first bidirectional switch S1, the first pass terminal of the third bidirectional switch S3, and the first pass terminal of the fifth bidirectional switch S5 are all connected to the output inductor L. ac The second terminal is connected to the AC power source e. The second terminal of the second bidirectional switch S2, the second terminal of the fourth bidirectional switch S4, and the second terminal of the sixth bidirectional switch S6 are all connected to the AC power source e. in The second terminal b is connected, wherein the connection between the second path terminal of the first bidirectional switch S1 and the first path terminal of the second bidirectional switch S2, the connection between the second path terminal of the third bidirectional switch S3 and the first path terminal of the fourth bidirectional switch S4, and the connection between the second path terminal of the fifth bidirectional switch S5 and the first path terminal of the sixth bidirectional switch S6 serve as the output terminals of the first phase bridge arm, the second phase bridge arm, and the third phase bridge arm, respectively, to output the first output current i. U Second output current i V and the third output current i W At the same time, only one of the first bidirectional switch S1, the third bidirectional switch S3 and the fifth bidirectional switch S5 is turned on, and only one of the second bidirectional switch S2, the fourth bidirectional switch S4 and the sixth bidirectional switch S6 is turned on, so as to form a unique current path for the conversion module 20.

[0045] That is, in this embodiment, at any given time, only one upper bridge arm of all bridge arms in the conversion module 20 can be turned on, and only one lower bridge arm of all bridge arms can be turned on. At any given time, there is only one current path in the conversion module 20.

[0046] Optionally, based on the above embodiments, in this embodiment, when the first bidirectional switch S1 and the second bidirectional switch S2 are in the on state, the third bidirectional switch S3 and the fourth bidirectional switch S4 are in the on state, or the fifth bidirectional switch S5 and the sixth bidirectional switch S6 are in the on state, the conversion module 20 outputs a zero current vector; when the first bidirectional switch S1 and the sixth bidirectional switch S6 are in the on state, the third bidirectional switch S3 and the sixth bidirectional switch S6 are in the on state, the third bidirectional switch S3 and the second bidirectional switch S2 are in the on state, the fifth bidirectional switch S5 and the second bidirectional switch S2 are in the on state, the fifth bidirectional switch S5 and the fourth bidirectional switch S4 are in the on state, or the first bidirectional switch S1 and the fourth bidirectional switch S4 are in the on state, the conversion module 20 outputs a valid current vector.

[0047] In this embodiment, please refer to Figure 3 , Figure 3 This is a schematic diagram of an embodiment of the current space vector provided in this application. Figure 3 As shown, I7 to I9 represent zero current vectors; I1 to I6 represent effective current vectors. As previously mentioned, in this embodiment, depending on the different bidirectional switches that are turned on, the conversion module 20 can output six effective current vectors (I1 to I6) and three zero current vectors (I7 to I9). Specifically, when the first bidirectional switch S1 and the second bidirectional switch S2 are in the on state, the third bidirectional switch S3 and the fourth bidirectional switch S4 are in the on state, or the fifth bidirectional switch S5 and the sixth bidirectional switch S6 are in the on state, the conversion module 20 can output as follows: Figure 3 The zero current vectors shown are I7, I8, or I9; when the first bidirectional switch S1 and the sixth bidirectional switch S6 are in the on state, the conversion module 20 can output as shown in the figure. Figure 3 The effective current vector I1 shown indicates that when the third bidirectional switch S3 and the sixth bidirectional switch S6 are in the on state, the conversion module 20 can output as follows: Figure 3 The effective current vector I2 shown indicates that when the second bidirectional switch S2 and the third bidirectional switch S3 are in the on state, the conversion module 20 can output as follows: Figure 3 The effective current vector I3 shown indicates that when the second bidirectional switch S2 and the fifth bidirectional switch S5 are in the on state, the conversion module 20 can output as follows: Figure 3 The effective current vector I4 shown indicates that when the fourth bidirectional switch S4 and the fifth bidirectional switch S5 are in the on state, the conversion module 20 can output as follows: Figure 3 The effective current vector I5 shown indicates that when the first bidirectional switch S1 and the fourth bidirectional switch S4 are in the on state, the conversion module 20 can output as follows: Figure 3 The effective current vector I6 is shown.

[0048] Optionally, such as Figure 1and Figure 2 As shown, in this embodiment, the AC to AC converter circuit 100 further includes a filter and freewheeling module 30. The filter and freewheeling module 30 is connected to the connection between the converter module 20 and the load, and is used to filter and freewheel the output current.

[0049] In this embodiment, since the output current may be zero, a filter freewheeling module 30 is provided to avoid the load being without power. The filter freewheeling module 30 can not only filter the output current, but also provide freewheeling power to the load when the output current is zero.

[0050] Optionally, such as Figure 1 and Figure 2 As shown, in this embodiment, the filter freewheeling module 30 includes a first capacitor C. u Second capacitor C v Third capacitor C w The first capacitor C u First terminal, second capacitor C v The first terminal and the third capacitor C w The first terminal is connected to the output terminals of the first phase bridge arm, the second phase bridge arm, and the third phase bridge arm, respectively; the first capacitor C u The second terminal, the second capacitor C v The second terminal and the third capacitor C w The second end is connected together.

[0051] In this embodiment, the filter freewheeling module 30 can be configured as a capacitor. When the output current is output, the high-frequency components in the output current flow to the first capacitor C. u Second capacitor C v and the third capacitor C w The low-frequency component of the output current flows to the load. When the output current is zero, the first capacitor C... u Second capacitor C v and the third capacitor C w It can supply power to the load, thereby achieving current freewheeling and avoiding sudden changes in current. In other embodiments, the filter freewheeling module 30 can also be configured with other circuit structures, as long as it meets the freewheeling filtering function, which is not limited here.

[0052] Furthermore, in this embodiment, the first capacitor C u Second capacitor C v and the third capacitor C w Ceramic capacitors, film capacitors, and other types of capacitors can be used. In this embodiment, different filtering effects can also be achieved by adjusting the capacitance parameters.

[0053] Optionally, based on the above embodiments, in this embodiment, the output inductor L ac Inductor current i ac AC power supply e in Input current i in With AC power e in The voltage is configured as a sine wave in phase.

[0054] In this embodiment, the output inductor L can be... ac Inductor current i ac AC power supply e in Input current i in With AC power e in The voltage is configured as a sine wave in phase, which ensures a high power factor and low current harmonics at the input.

[0055] Optionally, based on the above embodiments, in this embodiment, the bidirectional switch includes a bidirectional gallium nitride switch, a bidirectional insulated gate bipolar transistor switch, or a bidirectional metal-oxide-semiconductor field-effect transistor switch.

[0056] In this embodiment, the bidirectional switch is preferably configured as a bidirectional gallium nitride (GaN) switch. Using a bidirectional GaN switch can improve switching speed, reduce switching losses, and increase efficiency. In other embodiments, the bidirectional switch can also be configured as a bidirectional insulated-gate bipolar transistor (IGBT) switch or a bidirectional metal-oxide-semiconductor (MOSFET) field-effect transistor (MOSFET) switch, wherein the bidirectional IGBT switch needs to be connected in reverse series.

[0057] Optionally, based on the above embodiments, in this embodiment, the bidirectional switch can be configured as two unidirectional switches connected in series, wherein when the two unidirectional switches are connected in series, the drains or sources of the two unidirectional switches are connected.

[0058] In this embodiment, the bidirectional switch can also be configured as two unidirectional switches connected in series. If it is a unidirectional insulated-gate bipolar transistor switch or a metal-oxide-semiconductor field-effect transistor switch, this application requires 14 unidirectional switches. In addition, if it is configured as two unidirectional switches, the two unidirectional switches need to be connected in series back to back, that is, the drains or sources of the two unidirectional switches are connected.

[0059] Optionally, please refer to Figure 4 , Figure 4 This is a schematic diagram of the structure of an embodiment of the motor device provided in this application. Figure 4 As shown, the motor device in this embodiment includes the AC to AC conversion circuit 100 and the control module 110 of any of the above embodiments.

[0060] The control module 110 is connected to the current source input module 10 and the conversion module 20 respectively, and is used to control the conduction and cutoff of all bidirectional switches so that the AC to AC conversion circuit 100 can realize voltage and frequency conversion control.

[0061] That is, as mentioned above, in this embodiment, the control module 110 can control the output current by reasonably combining the switching sequence of the above seven bidirectional switches, thereby achieving the purpose of variable voltage and variable frequency control.

[0062] In other embodiments, the AC to AC converter circuit 100 of this embodiment can also be applied to other electronic devices that require AC conversion, and is not limited to the motor device 200.

[0063] Optionally, based on the above embodiments, in this embodiment, the control module 110 is further configured to sample the input current i of the current source input module 10. in and the output current of the conversion module 20, and based on the output requirements, the input current i in The output current is controlled in a closed loop to obtain the instantaneous modulation ratio of each phase arm. The instantaneous modulation ratio is used to adjust the amplitude and frequency of the output current of each phase arm so that the AC to AC converter circuit 100 can achieve variable voltage and variable frequency control.

[0064] In this embodiment, the first output current i of the conversion module 20 U Second output current i V and the third output current i W With inductor current i ac The relationship is shown in formula (1):

[0065]

[0066] Among them, i U Represented as the first output current, i V Represented as the second output current, i W Represented as the third output current, m a m b m c i represents the instantaneous modulation ratio of each phase arm. ac This is expressed as inductor current. Taking a permanent magnet synchronous motor as an example, in the control of a permanent magnet synchronous motor, its outer loop is the speed loop, and its inner loop is the current loop. The current loop output can be obtained by coordinate transformation and modulation, which yields m. a m b m c In this embodiment, by changing m a m b m c By adjusting the frequency and amplitude, the purpose of variable frequency control can be achieved.

[0067] Please see Figure 5 , Figure 5 This is a schematic diagram of the algorithm flow of one embodiment of the control module of this application. Figure 5 As shown, the control module 110 in this embodiment can sample the input side to obtain the input current i of the current source input module 10. in The output side is sampled to obtain the load current of the load. Based on the output power, voltage, and other requirements, the input current i is adjusted according to the output requirements. in The load current is controlled in a closed loop to generate the corresponding modulation ratio signal as described above. Then, based on the modulation ratio signal, a drive signal is generated through PWM modulation, hysteresis control and other methods. The drive signal controls the conduction and cutoff of the seven bidirectional switches mentioned above, so that the AC to AC converter circuit 100 can realize voltage and frequency conversion control.

[0068] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. An AC-to-AC converter circuit, characterized in that, It includes a current source input module and a conversion module. The current source input module is connected to the conversion module and is used to provide inductor current. The conversion module is used to provide output current to the load based on the inductor current. The current source input module includes a bidirectional switch and an output inductor. The bidirectional switch controls the magnitude of the inductor current output by the output inductor. The conversion module includes three phase arms: a first phase arm, a second phase arm, and a third phase arm. Each phase arm includes two bidirectional switches connected in series. The current source input module and the conversion module are configured to be connected to a control module so that the control module controls the on / off state of all the bidirectional switches, thereby realizing the voltage and frequency conversion control of the AC-to-AC conversion circuit.

2. The AC-to-AC converter circuit according to claim 1, characterized in that, The current source input module includes an AC power supply, a seventh bidirectional switch, and the output inductor. The first end of the AC power supply is connected to the first path end of the seventh bidirectional switch, the second path end of the seventh bidirectional switch is connected to the first end of the output inductor, the second end of the output inductor is connected to the second end of the AC power supply, and the connection between the second path end of the seventh bidirectional switch and the first end of the output inductor serves as the output terminal.

3. The AC-to-AC converter circuit according to claim 1, characterized in that, The current source input module also includes a filter capacitor and a filter inductor. The first end of the filter inductor is connected to the first end of the AC power supply. The second end of the filter inductor is connected to the first end of the seventh bidirectional switch and the first end of the filter capacitor. The second end of the filter capacitor is connected to the second end of the AC power supply.

4. The AC-to-AC converter circuit according to claim 2 or claim 3, characterized in that, When the seventh bidirectional switch is in the ON state, and the conversion module outputs a zero vector current, the AC power supply charges the output inductor, causing the inductor current to rise. When the seventh bidirectional switch is in the off state, and the conversion module outputs the zero current vector, the output inductor continues to flow through the bridge arm directly connected to the conversion module, and the inductor current remains unchanged. When the seventh bidirectional switch is in the off state, and the conversion module outputs an effective current vector in coordination, the output inductor discharges to the load, and the inductor current decreases.

5. The AC-to-AC converter circuit according to claim 2 or claim 3, characterized in that, The output current includes a first output current, a second output current, and a third output current. The first phase bridge arm includes a first bidirectional switch and a second bidirectional switch connected in series. The second phase bridge arm includes a third bidirectional switch and a fourth bidirectional switch connected in series. The third phase bridge arm includes a fifth bidirectional switch and a sixth bidirectional switch connected in series. The first path terminal of the first bidirectional switch, the first path terminal of the third bidirectional switch, and the first path terminal of the fifth bidirectional switch are all connected to the second terminal of the output inductor. The second path terminals of the second bidirectional switch, the second path terminals of the fourth bidirectional switch, and the second path terminals of the sixth bidirectional switch are all connected to the second terminal of the AC power supply. The connection points between the second path terminals of the first bidirectional switch and the first path terminals of the second bidirectional switch, the connection points between the second path terminals of the third bidirectional switch and the first path terminals of the fourth bidirectional switch, and the connection points between the second path terminals of the fifth bidirectional switch and the first path terminals of the sixth bidirectional switch serve as the output terminals of the first phase bridge arm, the second phase bridge arm, and the third phase bridge arm, respectively, to output the first output current, the second output current, and the third output current. At any given time, only one of the first, third, and fifth bidirectional switches is conducting, and only one of the second, fourth, and sixth bidirectional switches is conducting, thus forming a unique current path for the conversion module.

6. The AC-to-AC converter circuit according to claim 5, characterized in that, When the first and second bidirectional switches are in the ON state, the third and fourth bidirectional switches are in the ON state, or the fifth and sixth bidirectional switches are in the ON state, the conversion module outputs a zero current vector; when the first and sixth bidirectional switches are in the ON state, the third and sixth bidirectional switches are in the ON state, the third and second bidirectional switches are in the ON state, the fifth and second bidirectional switches are in the ON state, the fifth and fourth bidirectional switches are in the ON state, or the first and fourth bidirectional switches are in the ON state, the conversion module outputs a valid current vector.

7. The AC-to-AC converter circuit according to claim 1, characterized in that, It also includes a filter and freewheeling module, which is connected at the connection between the conversion module and the load, and is used to filter and freewheel the output current.

8. The AC-to-AC converter circuit according to claim 7, characterized in that, The filter freewheeling module includes a first capacitor, a second capacitor, and a third capacitor. The first end of the first capacitor, the first end of the second capacitor, and the first end of the third capacitor are respectively connected to the output end of the first phase bridge arm, the output end of the second phase bridge arm, and the output end of the third phase bridge arm. The second ends of the first capacitor, the second end of the second capacitor, and the second end of the third capacitor are connected together.

9. The AC-to-AC converter circuit according to claim 2 or claim 3, characterized in that, The inductor current of the output inductor, the input current of the AC power supply, and the voltage of the AC power supply are configured as in-phase sine waves.

10. The AC-to-AC converter circuit according to claim 1, characterized in that, The bidirectional switch includes a bidirectional gallium nitride switch, a bidirectional insulated gate bipolar transistor switch, or a bidirectional metal-oxide-semiconductor field-effect transistor switch.

11. The AC-to-AC converter circuit according to claim 1, characterized in that, The bidirectional switch can be configured as two unidirectional switches connected in series, wherein when the two unidirectional switches are connected in series, the drains or sources of the two unidirectional switches are connected.

12. A motor device, characterized in that, The AC-to-AC conversion circuit and control module according to any one of claims 1-11 are included. The control module is connected to the current source input module and the conversion module respectively, and is used to control the on and off of all the bidirectional switches so that the AC-to-AC conversion circuit can realize voltage and frequency conversion control.

13. The motor device according to claim 12, characterized in that, The control module is also used to sample the input current of the current source input module and the output current of the conversion module, and to perform closed-loop control on the input current and output current based on the output requirements to obtain the instantaneous modulation ratio of each phase arm. The instantaneous modulation ratio is used to adjust the amplitude and frequency of the output current of each phase arm so that the AC to AC conversion circuit can achieve variable voltage and variable frequency control.

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