AC-DC-AC converter and control system

Abstract

The application provides an AC-DC converter and a control system, wherein the AC-DC converter comprises three AC-DC conversion sub-modules, each of which comprises a filter unit, a switching and capacitor unit and a voltage transformation and rectification unit; the input end of the filter unit is used for being connected with any two phases of a three-phase power supply; the output end of the filter unit is connected with the input end of the switching and capacitor unit; the output end of the switching and capacitor unit is connected with the input end of the voltage transformation and rectification unit; the positive output end of the voltage transformation and rectification unit is connected with the positive output terminal of the AC-DC converter; and the negative output end of the voltage transformation and rectification unit is connected with the negative output terminal of the AC-DC converter, so that DC and AC isolation can be realized while current shaping is taken into account.

Description

Technical Field

[0001] This application relates to the field of AC-DC converter technology, and particularly to an AC-DC converter and control system. Background Technology

[0002] AC-DC converters are widely used in industrial fields such as rail transportation to convert AC to DC to power DC-powered equipment. To ensure compatibility between AC-DC converters and other AC-powered equipment and to improve the capacity utilization of the AC power supply, filtering is typically used to make the input current of the AC-DC converter sinusoidal. For the safety of equipment and personnel, electrical isolation is usually required between different voltage levels of the AC-DC converter.

[0003] Figure 1 This is a schematic diagram of the structure of an AC-DC converter provided in related technologies, such as... Figure 1 As shown, in related technologies, the front-end AC / DC converter uses a large-capacity low-pass filter to improve the input current, and the rear-end DC / DC converter uses a DC / DC converter for isolation. However, the AC / DC converters provided by related technologies have the following drawbacks: the two-stage conversion results in a large number of conversion stages in existing AC / DC isolation converters, poor front-end filtering effect, and bulky AC / DC converters. Summary of the Invention

[0004] In view of the problems in the above-mentioned related technologies, this application provides an AC-DC converter and control system.

[0005] This application provides a control method comprising: three AC-DC conversion submodules, each comprising: a filtering unit, a switching and capacitor unit, and a transformer and rectifier unit; wherein the input terminal of the filtering unit is connected to any two phases of the three-phase power supply, the output terminal of the filtering unit is connected to the input terminal of the switching and capacitor unit, the output terminal of the switching and capacitor unit is connected to the input terminal of the transformer and rectifier unit, the positive output terminal of the transformer and rectifier unit is connected to the positive output terminal of the AC-DC converter, and the negative output terminal of the transformer and rectifier unit is connected to the negative output terminal of the AC-DC converter.

[0006] In some embodiments, the input terminals of the switch and capacitor unit include a first input terminal and a second input terminal, and the filter unit includes a first AC inductor, a second AC inductor, and an AC capacitor. The input terminal of the first AC inductor is connected to one of any two phases, the output terminal of the first AC inductor is connected to the input terminal of the second AC inductor and one end of the AC capacitor, the output terminal of the second AC inductor is connected to the first input terminal, and the other end of the AC capacitor is connected to the other of the any two phases and the second input terminal.

[0007] In some embodiments, the input terminals of the switch and capacitor unit include a first input terminal and a second input terminal, and the filter unit includes a first AC inductor, a second AC inductor, and an AC capacitor. The input terminal of the first AC inductor is connected to one of any two phases, the output terminal of the first AC inductor is connected to the input terminal of the second AC inductor and one end of the AC capacitor, the output terminal of the second AC inductor is connected to the second input terminal, and the other end of the AC capacitor is connected to the other of any two phases and the first input terminal.

[0008] In some embodiments, the transformer and rectifier unit includes a third input terminal and a fourth input terminal, and the switch and capacitor unit includes a first rectifier diode, a second rectifier diode, a first fully controlled semiconductor switch, a second fully controlled semiconductor switch, a first switched capacitor, and a second switched capacitor. The anode of the first rectifier diode is connected to the cathode of the second diode switch and the second input terminal. The cathode of the first rectifier diode is connected to one end of the first fully controlled semiconductor switch and one end of the first switched capacitor. The anode of the second rectifier diode is connected to one end of the second fully controlled semiconductor switch and one end of the second switched capacitor. The other end of the first fully controlled semiconductor switch is connected to the first input terminal, the other end of the second fully controlled semiconductor switch, and the third input terminal. The other end of the first switched capacitor is connected to the other end of the second switched capacitor and the fourth input terminal.

[0009] In some embodiments, the transformer and rectifier unit includes a third input terminal and a fourth input terminal, and the switch and capacitor unit includes a first rectifier diode, a second rectifier diode, a first fully controlled semiconductor switch, a second fully controlled semiconductor switch, a first switched capacitor, and a second switched capacitor. The anode of the first rectifier diode is connected to the cathode of the second rectifier diode and the first input terminal. The cathode of the first rectifier diode is connected to one end of the first fully controlled semiconductor switch and one end of the first switched capacitor. The anode of the second rectifier diode is connected to one end of the second fully controlled semiconductor switch and one end of the second switched capacitor. The other end of the first fully controlled semiconductor switch is connected to the second input terminal, the other end of the second fully controlled semiconductor switch, and the third input terminal. The other end of the first switched capacitor is connected to the other end of the second switched capacitor and the fourth input terminal.

[0010] In some embodiments, the transformer and rectifier unit further includes: a high-frequency transformer, a third rectifier diode, a fourth rectifier diode, and a DC capacitor. The high-frequency transformer includes: a first coil, a second coil, and a third coil. The two pins of the first coil are respectively connected to the third input terminal and the fourth input terminal. The second coil and the third coil share a second pin. The first pin of the second coil is connected to the positive terminal of the third rectifier diode. The negative terminal of the third rectifier diode is connected to one end of the DC capacitor, the negative terminal of the fourth rectifier diode, and the positive output terminal. The third pin of the third coil is connected to the positive terminal of the fourth rectifier diode. The second pin is connected to the other end of the DC capacitor and the negative output terminal.

[0011] In some embodiments, the transformer and rectifier unit further includes: a high-frequency transformer, a third rectifier diode, a fourth rectifier diode, a fifth rectifier diode, a sixth rectifier diode, and a DC capacitor. The high-frequency transformer includes: a first coil and a second coil. The two pins of the first coil are respectively connected to the third input terminal and the fourth input terminal. The anode of the third rectifier diode is connected to the first pin of the second coil and the cathode of the fourth rectifier diode. The cathode of the third rectifier diode is connected to the cathode of the fifth rectifier diode, one end of the DC capacitor, and the positive output terminal. The anode of the fourth rectifier diode is connected to the anode of the sixth rectifier diode, the other end of the DC capacitor, and the negative output terminal. The anode of the fifth rectifier diode is connected to the cathode of the sixth rectifier diode and the second pin of the second coil.

[0012] This application provides a control system, including: an AC-DC converter as described in any of the above claims, and a control unit, wherein the control unit is configured to acquire electrical signals from each AC-DC conversion submodule and the output terminal of the AC-DC converter, generate driving signals corresponding to each AC-DC conversion submodule based on the electrical signals, and drive each AC-DC conversion submodule to send the driving signals corresponding to each AC-DC conversion submodule to each AC-DC conversion submodule, wherein the driving signals corresponding to any two AC-DC conversion submodules have a 120° phase difference and equal frequencies.

[0013] In some embodiments, the electrical signal includes a voltage signal and a current signal, and the control unit includes:

[0014] The system includes three pulse generation circuits and a proportional-integral (PI) operation circuit. The PI operation circuit is connected to the output of the AC-DC converter. It acquires a first voltage signal output by the AC-DC converter, performs analog-to-digital conversion on the first piezoelectric signal to obtain a second voltage signal, adds the second voltage signal to a set value to obtain a first calculation result, and performs a proportional-integral operation on the first calculation result to obtain a second calculation result. Each pulse generation circuit is connected to a corresponding AC-DC conversion submodule. Each pulse generation circuit acquires a second voltage signal and a first current signal from each AC-DC conversion submodule, performs analog-to-digital conversion on the second voltage signal to obtain a third voltage signal, performs analog-to-digital conversion on the first current signal to obtain a second current signal, multiplies the third voltage signal with the second calculation result to obtain a third calculation result, adds the third calculation result to the second current signal, and then performs a proportional-integral operation to obtain a fourth calculation result. A pulse signal is generated based on the fourth calculation result, and the drive signal for each AC-DC conversion submodule is obtained based on the pulse signal.

[0015] In some embodiments, the proportional-integral (PI) operation circuit includes: a first sensor, a first analog-to-digital converter, a first multiplier, and a first proportional-integral (PI) operator. The first sensor is connected to the output terminal of the AC-DC converter. The first sensor is connected in series with the first analog-to-digital converter, the first multiplier, and the first PI operator. The first PI operator is connected to each pulse generation circuit.

[0016] In some embodiments, the pulse generation circuit includes: a second sensor, a second analog-to-digital converter (ADC), a second multiplier, a third ADC, a first adder, a second proportional-integral (PI) arithmetic unit, a pulse generator, and a driver. The second sensor is connected to an AC-DC conversion submodule. The second sensor is used to acquire a second voltage signal from each AC-DC conversion submodule. The second sensor is connected in series with the second ADC, the second multiplier, the first adder, the second PI arithmetic unit, the pulse generator, and the driver. The third ADC is used to acquire a first current signal from the corresponding AC-DC conversion submodule and perform analog-to-digital conversion on the first current signal to obtain a second current signal. The third ADC inputs the second current signal to the first adder. The pulse generator generates a pulse, and the driver isolates and amplifies the pulse to obtain a drive signal.

[0017] This application provides an AC-DC converter and control system, which sets up three AC-DC conversion sub-modules. Each AC-DC conversion sub-module includes: a filtering unit, a switching and capacitor unit, and a transformer and rectifier unit. The input terminal of the filtering unit is connected to any two of the three phases, the output terminal of the filtering unit is connected to the input terminal of the switching and capacitor unit, the output terminal of the switching and capacitor unit is connected to the input terminal of the transformer and rectifier unit, the positive output terminal of the transformer and rectifier unit is connected to the positive output terminal of the AC-DC converter, and the negative output terminal of the transformer and rectifier unit is connected to the negative output terminal of the AC-DC converter. This system can achieve DC and AC isolation while also providing current shaping. Attached Figure Description

[0018] The present application will be described in more detail below based on embodiments and with reference to the accompanying drawings.

[0019] Figure 1 This is a schematic diagram of the structure of an AC-DC converter provided in related technologies;

[0020] Figure 2 A schematic diagram of the connection structure of an AC-DC converter provided in an embodiment of this application;

[0021] Figure 3 This is a schematic diagram of the structure of an AC-DC conversion submodule provided in an embodiment of this application;

[0022] Figure 4 This is a schematic diagram of the structure of a filtering unit provided in an embodiment of this application;

[0023] Figure 5 This is a schematic diagram of the connection structure of another filtering unit provided in an embodiment of this application;

[0024] Figure 6 This is a schematic diagram of the structure of a switch and capacitor unit provided in an embodiment of this application;

[0025] Figure 7 This is a schematic diagram of another switch and capacitor unit provided in an embodiment of this application;

[0026] Figure 8 This is a schematic diagram of the structure of a transformer and rectifier unit provided in an embodiment of this application;

[0027] Figure 9 This is a schematic diagram of the structure of a transformer and rectifier unit provided in an embodiment of this application;

[0028] Figure 10 This is a schematic diagram of the structure of an AC-DC conversion submodule provided in an embodiment of this application;

[0029] Figure 11 To adopt Figure 10 A schematic diagram of the AC-DC converter constructed from the provided AC-DC conversion submodules;

[0030] Figure 12 This is a schematic diagram of another AC-DC converter provided in an embodiment of this application;

[0031] Figure 13 A schematic diagram of another AC-DC converter provided in the embodiments of this application;

[0032] Figure 14 A schematic diagram of the structure of a control system provided in an embodiment of this application;

[0033] Figure 15 A schematic diagram of a driving signal provided in an embodiment of this application;

[0034] Figure 16 A schematic diagram of the current in an AC-DC conversion submodule provided in an embodiment of this application;

[0035] Figure 17 This is a schematic diagram of an input voltage, input current, and output voltage provided for an embodiment of this application.

[0036] In the accompanying drawings, the same parts are referred to by the same reference numerals, and the drawings are not drawn to scale. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The described embodiments should not be regarded as limitations on this application. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0039] If the application documents contain similar descriptions such as "first, second, third", the following explanation shall be added: In the following description, the terms "first, second, third" are used only to distinguish similar objects and do not represent a specific order of objects. It is understood that "first, second, third" may be interchanged in a specific order or sequence where permitted, so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein.

[0040] 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 belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0041] Based on the problems existing in related technologies, this application provides an AC-DC converter, including: three AC-DC conversion submodules, each submodule's input terminal connected to any two phases of a three-phase AC power supply, each submodule's positive output terminal connected to the positive output terminal of the AC-DC converter, and each submodule's negative output terminal connected to the negative output terminal of the AC-DC converter. Exemplarily, in this application embodiment, the AC-DC converter's input terminals can be configured to be connected to the three-phase power supply. Figure 2 This is a schematic diagram of the connection structure of an AC-DC converter provided in an embodiment of this application, as shown below. Figure 2 As shown, the input terminals U and V of the AC-DC converter are connected to the input terminals X and Y of the first AC-DC converter submodule; the input terminals V and W of the AC-DC converter are connected to the input terminals X and Y of the second AC-DC converter submodule; the input terminals W and U of the AC-DC converter are connected to the input terminals X and Y of the third AC-DC converter submodule; the positive output terminal + of the AC-DC converter is connected to the output terminals P of the first AC-DC converter submodule, the second AC-DC converter submodule, and the third AC-DC converter submodule; the negative output terminal - of the AC-DC converter is connected to the output terminals N of the first AC-DC converter submodule, the second AC-DC converter submodule, and the third AC-DC converter submodule.

[0042] In some embodiments, each AC-DC converter submodule includes: a filtering unit, a switching and capacitor unit, and a transformer and rectifier unit. The input terminal of the filtering unit is connected to any two of the three phases; the output terminal of the filtering unit is connected to the input terminal of the switching and capacitor unit; the output terminal of the switching and capacitor unit is connected to the input terminal of the transformer and rectifier unit; the positive output terminal of the transformer and rectifier unit is connected to the positive output terminal of the AC-DC converter; and the negative output terminal of the transformer and rectifier unit is connected to the negative output terminal of the AC-DC converter.

[0043] Following the example above, Figure 3 This is a schematic diagram of the structure of an AC-DC conversion submodule provided in an embodiment of this application, as shown below. Figure 3 As shown, the input terminals X and Y of the filter unit; the output terminals A and B of the filter unit (110) serve as the inputs of the switch and capacitor unit (120); the output terminals C and D of the switch and capacitor unit (120) serve as the inputs of the transformer and rectifier unit (130); and the output of the transformer and rectifier unit (130) is the output terminals P and N of the AC-DC converter submodule (100).

[0044] In some embodiments, the input terminals of the switch and capacitor unit include a first input terminal and a second input terminal, and the filter unit includes a first AC inductor, a second AC inductor, and an AC capacitor. The input terminal of the first AC inductor is connected to one of any two phases, the output terminal of the first AC inductor is connected to the input terminal of the second AC inductor and one end of the AC capacitor, the output terminal of the second AC inductor is connected to the first input terminal, and the other end of the AC capacitor is connected to the other of any two phases and the second input terminal.

[0045] Following the example above, Figure 4 This is a schematic diagram of the structure of a filtering unit provided in an embodiment of this application, such as... Figure 4 As shown, the input terminals of the switch and capacitor unit include: a first input terminal A and a second input terminal B. The filter unit 110 includes: a first AC inductor Lf1, a second AC inductor Lf2 and an AC capacitor Cf1. The input terminal (X) of the first AC inductor Lf1 is connected to one of any two phases. The output terminal of the first AC inductor Lf1 is connected to the input terminal of the second AC inductor Lf2 and one end of the AC capacitor Cf1. The output terminal of the second AC inductor Lf2 is connected to the first input terminal A. The other end of the AC capacitor Cf1 is connected to the other phase (Y) of any two phases and the second input terminal A.

[0046] In some embodiments, the input terminals of the switch and capacitor unit include a first input terminal and a second input terminal, and the filter unit includes a first AC inductor, a second AC inductor, and an AC capacitor. The input terminal of the first AC inductor is connected to one of any two phases, the output terminal of the first AC inductor is connected to the input terminal of the second AC inductor and one end of the AC capacitor, the output terminal of the second AC inductor is connected to the second input terminal, and the other end of the AC capacitor is connected to the other of any two phases and the first input terminal.

[0047] Following the example above, Figure 5 This is a schematic diagram of the connection structure of another filtering unit provided in an embodiment of this application, as shown below. Figure 5As shown, the input terminals of the switch and capacitor unit include: a first input terminal A and a second input terminal B. The filter unit 110 includes: a first AC inductor Lf1, a second AC inductor Lf2 and an AC capacitor Cf1. The input terminal (X) of the first AC inductor Lf1 is connected to one of any two phases. The output terminal of the first AC inductor Lf1 is connected to the input terminal of the second AC inductor Lf2 and one end of the AC capacitor Cf1. The output terminal of the second AC inductor Lf2 is connected to the second input terminal B. The other end (X) of the AC capacitor Cf1 is connected to the other of any two phases and the first input terminal A.

[0048] In some embodiments, the transformer and rectifier unit includes a third input terminal and a fourth input terminal, and the switch and capacitor unit includes a first rectifier diode, a second rectifier diode, a first fully controlled semiconductor switch, a second fully controlled semiconductor switch, a first switched capacitor, and a second switched capacitor. The anode of the first rectifier diode is connected to the cathode of the second diode switch and the second input terminal. The cathode of the first rectifier diode is connected to one end of the first fully controlled semiconductor switch and one end of the first switched capacitor. The anode of the second rectifier diode is connected to one end of the second fully controlled semiconductor switch and one end of the second switched capacitor. The other end of the first fully controlled semiconductor switch is connected to the first input terminal, the other end of the second fully controlled semiconductor switch, and the third input terminal. The other end of the first switched capacitor is connected to the other end of the second switched capacitor and the fourth input terminal.

[0049] Following the example above, Figure 6 This is a schematic diagram of the structure of a switch and capacitor unit provided in an embodiment of this application, as shown below. Figure 6 As shown, the transformer and rectifier unit includes a third input terminal C and a fourth input terminal D. The switch and capacitor unit 120 includes a first rectifier diode D1, a second rectifier diode D2, a first fully controlled semiconductor switch Q1, a second fully controlled semiconductor switch Q2, a first switched capacitor C1, and a second switched capacitor C2. The positive terminal of the first rectifier diode D1 is connected to the negative terminal of the second diode switch D2 and the second input terminal B. The negative terminal of the first rectifier diode D1 is connected to one end of the first fully controlled semiconductor switch Q1 and one end of the first switched capacitor C1. The positive terminal of the second rectifier diode D2 is connected to one end of the second fully controlled semiconductor switch Q2 and one end of the second switched capacitor C2. The other end of the first fully controlled semiconductor switch Q1 is connected to the first input terminal A, the other end of the second fully controlled semiconductor switch Q2, and the third input terminal C. The other end of the first switched capacitor C1 is connected to the other end of the second switched capacitor C2 and the fourth input terminal D.

[0050] In some embodiments, the transformer and rectifier unit includes a third input terminal and a fourth input terminal, and the switch and capacitor unit includes a first rectifier diode, a second rectifier diode, a first fully controlled semiconductor switch, a second fully controlled semiconductor switch, a first switched capacitor, and a second switched capacitor. The anode of the first rectifier diode is connected to the cathode of the second rectifier diode and the first input terminal. The cathode of the first rectifier diode is connected to one end of the first fully controlled semiconductor switch and one end of the first switched capacitor. The anode of the second rectifier diode is connected to one end of the second fully controlled semiconductor switch and one end of the second switched capacitor. The other end of the first fully controlled semiconductor switch is connected to the second input terminal, the other end of the second fully controlled semiconductor switch, and the third input terminal. The other end of the first switched capacitor is connected to the other end of the second switched capacitor and the fourth input terminal.

[0051] Following the example above, Figure 7 This is a schematic diagram of another switch and capacitor unit provided in an embodiment of this application, as shown below. Figure 7 As shown, the transformer and rectifier unit includes a third input terminal C and a fourth input terminal D. The switch and capacitor unit 120 includes a first rectifier diode D1, a second rectifier diode D2, a first fully controlled semiconductor switch Q1, a second fully controlled semiconductor switch Q2, a first switched capacitor C1, and a second switched capacitor C2. The positive terminal of the first rectifier diode D1 is connected to the negative terminal of the second rectifier diode D2 and the first input terminal A. The negative terminal of the first rectifier diode D1 is connected to one end of the first fully controlled semiconductor switch Q1 and one end of the first switched capacitor C1. The positive terminal of the second rectifier diode D2 is connected to one end of the second fully controlled semiconductor switch Q2 and one end of the second switched capacitor C2. The other end of the first fully controlled semiconductor switch Q1 is connected to the second input terminal B, the other end of the second fully controlled semiconductor switch Q2, and the third input terminal C. The other end of the first switched capacitor C1 is connected to the other end of the second switched capacitor C2 and the fourth input terminal D.

[0052] In some embodiments, the transformer and rectifier unit further includes: a high-frequency transformer, a third rectifier diode, a fourth rectifier diode, and a DC capacitor. The high-frequency transformer includes: a first coil, a second coil, and a third coil. The two pins of the first coil are respectively connected to the third input terminal and the fourth input terminal. The second coil and the third coil share a second pin. The first pin of the second coil is connected to the positive terminal of the third rectifier diode. The negative terminal of the third rectifier diode is connected to one end of the DC capacitor, the negative terminal of the fourth rectifier diode, and the positive output terminal. The third pin of the third coil is connected to the positive terminal of the fourth rectifier diode. The second pin is connected to the other end of the DC capacitor and the negative output terminal.

[0053] Following the example above, Figure 8 This is a schematic diagram of the structure of a transformer and rectifier unit provided in an embodiment of this application, as shown below. Figure 8 As shown, the transformer and rectifier unit 130 further includes: a high-frequency transformer T1, a third rectifier diode Do1, a fourth rectifier diode Do2, and a DC capacitor Co. The high-frequency transformer T1 includes: a first coil, a second coil, and a third coil. The two pins of the first coil are respectively connected to the third input terminal C and the fourth input terminal D. The second coil and the third coil share a second pin. The first pin of the second coil is connected to the positive terminal of the third rectifier diode Do1. The negative terminal of the third rectifier diode Do1 is connected to one end of the DC capacitor Co, the negative terminal of the fourth rectifier diode Do2, and the positive output terminal P. The third pin of the third coil is connected to the positive terminal of the fourth rectifier diode Do2. The second pin is connected to the other end of the DC capacitor Co and the negative output terminal N.

[0054] In some embodiments, the transformer and rectifier unit further includes: a high-frequency transformer, a third rectifier diode, a fourth rectifier diode, a fifth rectifier diode, a sixth rectifier diode, and a DC capacitor. The high-frequency transformer includes: a first coil and a second coil. The two pins of the first coil are respectively connected to the third input terminal and the fourth input terminal. The anode of the third rectifier diode is connected to the first pin of the second coil and the cathode of the fourth rectifier diode. The cathode of the third rectifier diode is connected to the cathode of the fifth rectifier diode, one end of the DC capacitor, and the positive output terminal. The anode of the fourth rectifier diode is connected to the anode of the sixth rectifier diode, the other end of the DC capacitor, and the negative output terminal. The anode of the fifth rectifier diode is connected to the cathode of the sixth rectifier diode and the second pin of the second coil.

[0055] Following the example above, Figure 9This is a schematic diagram of the structure of a transformer and rectifier unit provided in an embodiment of this application, as shown below. Figure 9 As shown,

[0056] The transformer and rectifier unit 130 further includes: a high-frequency transformer T1, a third rectifier diode Do1, a fourth rectifier diode Do2, a fifth rectifier diode Do3, a sixth rectifier diode Do4, and a DC capacitor Co. The high-frequency transformer T1 includes: a first coil and a second coil. The two pins of the first coil are respectively connected to the third input terminal C and the fourth input terminal D. The positive terminal of the third rectifier diode Do1 is connected to the first pin of the second coil and the negative terminal of the fourth rectifier diode Do2. The negative terminal of the third rectifier diode Do1 is connected to the negative terminal of the fifth rectifier diode Do3, one end of the DC capacitor Co, and the positive output terminal P. The positive terminal of the fourth rectifier diode Do2 is connected to the positive terminal of the sixth rectifier diode Do4, the other end of the DC capacitor Co, and the negative output terminal N. The positive terminal of the fifth rectifier diode Do3 is connected to the negative terminal of the sixth rectifier diode Do4 and the second pin of the second coil.

[0057] For example, Figure 10 This is a schematic diagram of the structure of an AC-DC conversion submodule provided in an embodiment of this application, such as... Figure 10 As shown.

[0058] For example, Figure 11 To adopt Figure 10 A schematic diagram of the AC-DC converter constructed from the provided AC-DC conversion submodules.

[0059] By combining the above-mentioned filter unit, switch and capacitor unit, transformer and rectifier unit, the following AC-DC converters can also be obtained. Figure 12 This is a schematic diagram of another AC-DC converter provided in an embodiment of this application. Figure 13 This is a schematic diagram of another AC-DC converter provided in an embodiment of this application.

[0060] In the above embodiments, the phase difference between U, V, and W is 120°, and the fully controllable semiconductor switch can be Si-MOSFET, SiC-MOSFET, etc.

[0061] The embodiments of this application provide an isolated AC / DC converter with a single-stage converter, which has fewer conversion stages, simpler circuitry, higher efficiency, and lighter weight compared to traditional two-stage converters.

[0062] The AC-DC converter provided in this application embodiment achieves isolation conversion while also shaping the input current. It has better input current sinusoidality than traditional AC-DC converters and lower harmonic injection from AC input sources.

[0063] Based on the foregoing embodiments, this application further provides a control system, which includes: an AC-DC converter and a control unit provided in any of the above embodiments. The control unit is used to acquire electrical signals from the output terminals of each AC-DC conversion submodule and the AC-DC converter, generate driving signals corresponding to each AC-DC conversion submodule based on the electrical signals, and drive each AC-DC conversion submodule with the driving signals corresponding to each AC-DC conversion submodule. The driving signals corresponding to any two AC-DC conversion submodules have a 120° phase difference and equal frequencies.

[0064] In this embodiment of the application, the control unit includes:

[0065] The system includes three pulse generation circuits and a proportional-integral (PI) operation circuit. The PI operation circuit is connected to the output of the AC-DC converter. It acquires a first voltage signal output by the AC-DC converter, performs analog-to-digital conversion on the first piezoelectric signal to obtain a second voltage signal, adds the second voltage signal to a set value to obtain a first calculation result, and performs a proportional-integral operation on the first calculation result to obtain a second calculation result. Each pulse generation circuit is connected to a corresponding AC-DC conversion submodule. Each pulse generation circuit acquires a second voltage signal and a first current signal from each AC-DC conversion submodule, performs analog-to-digital conversion on the second voltage signal to obtain a third voltage signal, performs analog-to-digital conversion on the first current signal to obtain a second current signal, multiplies the third voltage signal with the second calculation result to obtain a third calculation result, adds the third calculation result to the second current signal, and then performs a proportional-integral operation to obtain a fourth calculation result. A pulse signal is generated based on the fourth calculation result, and the drive signal for each AC-DC conversion submodule is obtained based on the pulse signal.

[0066] Figure 14 A schematic diagram of the structure of a control system provided in an embodiment of this application is shown below. Figure 14 As shown,

[0067] The proportional-integral (PI) operation circuit includes: a first sensor 101, a first analog-to-digital converter 102, a first multiplier 103, and a first proportional-integral (PI) operator 104. The first sensor 101 is connected to the output terminal of the AC-DC converter. The first sensor 101 is connected in series with the first analog-to-digital converter 102, the first multiplier 103, and the first PI operator 104. The first PI operator 104 is connected to each pulse generation circuit.

[0068] In some embodiments, the pulse generation circuit includes: a second sensor 201, a second analog-to-digital converter 202, a second multiplier 203, a third analog-to-digital converter 204, a first adder 205, a second proportional-integral (PI) arithmetic unit 206, a pulse generator 207, and a driver 208. The second sensor 201 is connected to a corresponding AC / DC conversion submodule. The second sensor 201 is used to acquire a second voltage signal from each AC / DC conversion submodule. The second sensor 201 is connected in series with the second analog-to-digital converter 202, the second multiplier 203, the first adder 205, the second PI arithmetic unit 206, the pulse generator 207, and the driver 208. The third analog-to-digital converter 204 is used to convert the first current signal acquired from the corresponding AC / DC conversion submodule into a second current signal. The third analog-to-digital converter 204 inputs the second current signal to the first adder 205. The pulse generator 207 generates a pulse. The driver 208 isolates and amplifies the pulse to obtain a drive signal. The drive signal is sent to the corresponding fully controllable semiconductor switch.

[0069] In this embodiment, the Q1-Q6 drive signals are as follows: Figure 15 As shown. Figure 15 A schematic diagram of a driving signal provided in an embodiment of this application, such as... Figure 15 As shown, all AC / DC submodules operate at the same frequency, and the phase-to-phase drive signals have a 120° phase difference. The turn-on time ton and turn-off time toff are determined by the pulse generation operation method, and are usually taken as ton = toff. Under the action of the drive signal, the current of each AC / DC conversion submodule has a fundamental frequency component and a high-frequency component. Figure 16 A schematic diagram of the current in an AC-DC conversion submodule provided in an embodiment of this application is shown below. Figure 16 As shown, Id1 is the current of the first AC-DC converter sub-module, Id2 is the current of the second AC-DC converter sub-module, and Id3 is the current of the third AC-DC converter sub-module. The currents Id1, Id2, and Id3 contain power frequency fundamental wave components and high-frequency components. Figure 17 A schematic diagram of input voltage, input current, and output voltage provided for an embodiment of this application is shown below. Figure 17 As shown, under the action of the filter unit, the input current Ii waveform is sinusoidal and in phase with the input voltage Vi, thus having the characteristics of high power factor, low input harmonics, straight output voltage Vo, stable output voltage Vo waveform, and low ripple.

[0070] This application proposes a single-stage isolated AC / DC converter, which has fewer conversion stages, a simpler circuit, higher efficiency, and lighter weight compared to traditional two-stage converters. While achieving isolation conversion, it also provides input current shaping, resulting in better input current sinusoidality and lower harmonic injection from the AC input source compared to traditional AC / DC converters. The drive signals between the various AC / DC conversion submodules within this invention are 120° out of phase, and the output filtering is easier to design than that of traditional AC / DC converters.

[0071] It should be understood that the phrase "one embodiment" or "an embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of this application. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. It should be understood that in the various embodiments of this application, the sequence numbers of the above-described processes do not imply a sequential order of execution; the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application. The sequence numbers of the above-described embodiments are merely descriptive and do not represent the superiority or inferiority of the embodiments.

[0072] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0073] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods, such as: multiple units or components can be combined, or integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the various components shown or discussed can be through some interfaces, and the indirect coupling or communication connection between devices or units can be electrical, mechanical, or other forms.

[0074] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units. They may be located in one place or distributed across multiple network units. Some or all of the units may be selected to achieve the purpose of this embodiment according to actual needs.

[0075] In addition, each functional unit in the various embodiments of this application can be integrated into one processing unit, or each unit can be a separate unit, or two or more units can be integrated into one unit; the integrated unit can be implemented in hardware or in the form of hardware plus software functional units.

[0076] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various media that can store program code, such as mobile storage devices, read-only memory (ROM), magnetic disks, or optical disks.

[0077] Alternatively, if the integrated units described above are implemented as software functional modules and sold or used as independent products, they can also be stored in a computer-readable storage medium. Based on this understanding, the technical solutions of the embodiments of this application, or the parts that contribute to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a controller to execute all or part of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, ROMs, magnetic disks, or optical disks.

[0078] The above description is merely an embodiment of this application, but the scope of protection of this application is not limited thereto. Any modifications or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An AC-DC-AC converter, characterized in that include: The system comprises three AC-DC conversion submodules, each including a filter unit, a switch and capacitor unit, and a transformer and rectifier unit. The input terminal of the filter unit is connected to any two phases of the three-phase power supply. The output terminal of the filter unit is connected to the input terminal of the switch and capacitor unit, and the output terminal of the switch and capacitor unit is connected to the input terminal of the transformer and rectifier unit. The positive output terminal of the transformer and rectifier unit is connected to the positive output terminal of the AC-DC converter, and the negative output terminal of the transformer and rectifier unit is connected to the negative output terminal of the AC-DC converter. This system achieves DC and AC isolation while also providing current shaping. The input terminals of the switch and capacitor unit include: a first input terminal and a second input terminal; The transformer and rectifier unit includes: a third input terminal and a fourth input terminal; The switch and capacitor unit includes: a first rectifier diode, a second rectifier diode, a first fully controllable semiconductor switch, a second fully controllable semiconductor switch, a first switched capacitor, and a second switched capacitor. The anode of the first rectifier diode is connected to the cathode of the second diode switch and the second input terminal. The cathode of the first rectifier diode is connected to one end of the first fully controllable semiconductor switch and one end of the first switched capacitor. The anode of the second rectifier diode is connected to one end of the second fully controllable semiconductor switch and one end of the second switched capacitor. The other end of the first fully controllable semiconductor switch is connected to the first input terminal, the other end of the second fully controllable semiconductor switch, and the third input terminal. The other end of the first switched capacitor is connected to the other end of the second switched capacitor and the fourth input terminal. Alternatively, The switch and capacitor unit includes: a first rectifier diode, a second rectifier diode, a first fully controllable semiconductor switch, a second fully controllable semiconductor switch, a first switched capacitor, and a second switched capacitor. The anode of the first rectifier diode is connected to the cathode of the second rectifier diode and the first input terminal. The cathode of the first rectifier diode is connected to one end of the first fully controllable semiconductor switch and one end of the first switched capacitor. The anode of the second rectifier diode is connected to one end of the second fully controllable semiconductor switch and one end of the second switched capacitor. The other end of the first fully controllable semiconductor switch is connected to the second input terminal, the other end of the second fully controllable semiconductor switch, and the third input terminal. The other end of the first switched capacitor is connected to the other end of the second switched capacitor and the fourth input terminal.

2. The AC-DC converter according to claim 1, characterized in that, The filtering unit includes: a first AC inductor, a second AC inductor, and an AC capacitor. The input terminal of the first AC inductor is connected to one of any two phases. The output terminal of the first AC inductor is connected to the input terminal of the second AC inductor and one end of the AC capacitor. The output terminal of the second AC inductor is connected to the first input terminal. The other end of the AC capacitor is connected to the other of any two phases and the second input terminal.

3. The AC-DC converter according to claim 1, characterized in that, The filtering unit includes: a first AC inductor, a second AC inductor, and an AC capacitor. The input terminal of the first AC inductor is connected to one of any two phases. The output terminal of the first AC inductor is connected to the input terminal of the second AC inductor and one end of the AC capacitor. The output terminal of the second AC inductor is connected to the second input terminal. The other end of the AC capacitor is connected to the other of any two phases and the first input terminal.

4. The AC-DC converter according to claim 1, characterized in that, The transformer and rectifier unit further includes: a high-frequency transformer, a third rectifier diode, a fourth rectifier diode, and a DC capacitor. The high-frequency transformer includes: a first coil, a second coil, and a third coil. The two pins of the first coil are respectively connected to the third input terminal and the fourth input terminal. The second coil and the third coil share a second pin. The first pin of the second coil is connected to the positive terminal of the third rectifier diode. The negative terminal of the third rectifier diode is connected to one end of the DC capacitor, the negative terminal of the fourth rectifier diode, and the positive output terminal. The third pin of the third coil is connected to the positive terminal of the fourth rectifier diode. The second pin is connected to the other end of the DC capacitor and the negative output terminal.

5. The AC-DC converter according to claim 1, characterized in that, The transformer and rectifier unit further includes: a high-frequency transformer, a third rectifier diode, a fourth rectifier diode, a fifth rectifier diode, a sixth rectifier diode, and a DC capacitor. The high-frequency transformer includes: a first coil and a second coil. The two pins of the first coil are respectively connected to the third input terminal and the fourth input terminal. The positive terminal of the third rectifier diode is connected to the first pin of the second coil and the negative terminal of the fourth rectifier diode. The negative terminal of the third rectifier diode is connected to the negative terminal of the fifth rectifier diode, one end of the DC capacitor, and the positive output terminal. The positive terminal of the fourth rectifier diode is connected to the positive terminal of the sixth rectifier diode, the other end of the DC capacitor, and the negative output terminal. The positive terminal of the fifth rectifier diode is connected to the negative terminal of the sixth rectifier diode and the second pin of the second coil.

6. A control system, characterized in that, include: The AC-DC converter and control unit according to any one of claims 1-5, wherein the control unit is used to acquire electrical signals from the output terminals of each AC-DC conversion submodule and the AC-DC converter, generate driving signals corresponding to each AC-DC conversion submodule based on the electrical signals, and drive each AC-DC conversion submodule to send the driving signals corresponding to each AC-DC conversion submodule to each AC-DC conversion submodule, wherein the driving signals corresponding to any two AC-DC conversion submodules have a 120° phase difference and equal frequencies.

7. The control system according to claim 6, characterized in that, The electrical signals include: voltage signals and current signals, and the control unit includes: The system includes three pulse generation circuits and a proportional-integral (PI) operation circuit. The PI operation circuit is connected to the output terminal of the AC-DC converter. The PI operation circuit is used to acquire a first voltage signal output by the AC-DC converter, perform analog-to-digital conversion on the first voltage signal to obtain a second voltage signal, perform addition operation on the second voltage signal and a set value to obtain a first operation result, and perform proportional-integral operation on the first operation result to obtain a second operation result. Each pulse generation circuit is connected to a corresponding AC / DC conversion submodule. Each pulse generation circuit is used to acquire a second voltage signal and a first current signal from each AC / DC conversion submodule, perform analog-to-digital conversion on the second voltage signal to obtain a third voltage signal, perform analog-to-digital conversion on the first current signal to obtain a second current signal, multiply the third voltage signal with the second calculation result to obtain a third calculation result, add the third calculation result with the second current signal and then perform proportional-integral calculation to obtain a fourth calculation result, generate a pulse signal based on the fourth calculation result, and obtain the drive signal for each AC / DC conversion submodule based on the pulse signal.

8. The control system according to claim 7, characterized in that, The proportional-integral (PI) operation circuit includes: a first sensor, a first analog-to-digital converter, a first multiplier, and a first PI operator. The first sensor is connected to the output terminal of the AC-DC converter. The first sensor is connected in series with the first analog-to-digital converter, the first multiplier, and the first PI operator. The first PI operator is connected to each pulse generation circuit.

9. The control system according to claim 8, characterized in that, The pulse generation circuit includes: a second sensor, a second analog-to-digital converter (ADC), a second multiplier, a third ADC, a first adder, a second proportional-integral (PI) arithmetic unit, a pulse generator, and a driver. The second sensor is connected to a corresponding AC-DC conversion submodule. The second sensor is used to acquire a second voltage signal from each AC-DC conversion submodule. The second sensor is connected in series with the second ADC, the second multiplier, the first adder, the second PI arithmetic unit, the pulse generator, and the driver. The third ADC is used to acquire a first current signal from the corresponding AC-DC conversion submodule and perform analog-to-digital conversion on the first current signal to obtain a second current signal. The third ADC inputs the second current signal to the first adder. The pulse generator generates a pulse, and the driver isolates and amplifies the pulse to obtain a drive signal.

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