KR102624204B1 - Method and Device for Controlling Solid State Transformer - Google Patents

Abstract

Disclosed is a method and device for controlling a semiconductor transformer.
According to one aspect of the present invention, in the control device of a semiconductor transformer including a plurality of modules, - the module includes an AC/DC converter and a DC/DC converter -, a switch included in the plurality of AC/DC converters Provides a control device including a plurality of module controllers that generate first switching signals to control the plurality of AC/DC converters, and a voter that controls the plurality of AC/DC converters using signals synchronized from the first switching signals. do.

Description

{Method and Device for Controlling Solid State Transformer}

Embodiments of the present invention relate to a method and device for controlling a semiconductor transformer.

The content described in this section simply provides background information about the present invention and does not constitute prior art.

In the past, the power conversion system of railway vehicles consisted of a transformer and an AC/DC converter on the secondary side of the transformer. The transformer receives a voltage of 60Hz and 25kV through the catenary and lowers it to about 1kV to 3kV. Transformers are mainly implemented as iron core winding transformers that are inexpensive and have a simple structure. The AC/DC converter connected to the secondary side of the transformer converts AC voltage of several kV to DC voltage. The AC/DC converter then transfers the power to other devices.

Conventional power conversion systems have high reliability and are used in extra-high voltage distribution networks or power supply devices for railway vehicles.

However, the conventional power conversion system has limitations in that voltage fluctuations are large depending on the load size and there is no improvement in power quality or protection functions. Specifically, recent distribution networks adopt distributed power sources and have a bidirectional power supply function. When a power conversion system is applied to such a distribution network, voltage fluctuations in the power conversion system become severe due to bidirectional currents. Meanwhile, the power conversion system includes non-linear loads such as inverters. Due to the generation of harmonics in non-linear loads, the power quality of the power conversion system deteriorates. However, conventional power conversion systems do not have a function to improve power quality.

Furthermore, conventional power conversion systems do not have means to control the direct current output voltage of the AC/DC converter. In order for an iron core wound transformer in a power conversion system to transform the input voltage at a different ratio, the turns ratio of the windings must be changed. However, after manufacturing a power conversion system, it takes a lot of money and time to change the turns ratio.

The transformer and AC/DC converter in the power conversion system are the parts that take up the most load among the components in the railway vehicle. In particular, since the transformer operates at a low frequency of 60Hz, the value of inductance required for impedance matching inevitably increases. In order to increase the inductance of the transformer, many windings of the transformer must be wound or a large number of iron cores must be used, resulting in a large weight and volume, and a relatively low power density.

In order to solve the above-mentioned problems, research has been conducted on a transformer that uses semiconductor devices to increase the operating frequency of the transformer above 60 Hz. Specifically, a device was studied that converts low-frequency high-voltage input into high-frequency output using semiconductor devices and converts the high-frequency output into the voltage required for railroad vehicles through a high-frequency transformer. This is called a solid-state transformer or intelligent transformer.

Semiconductor transformers utilize power electronics technology to use higher frequencies than transformers in the existing commercial frequency band, which is advantageous for miniaturization and weight reduction. They also enable high-quality power supply through instantaneous voltage control and input/output of direct current voltage. has.

Figure 1 is a diagram illustrating a semiconductor transformer applied to a railroad vehicle.

Referring to Figure 1, a catenary 100 and a semiconductor transformer are shown. The semiconductor transformer consists of a plurality of power conversion modules (110, 120, and 130). The plurality of power conversion modules 110, 120, and 130 include a first power conversion module 110, a second power conversion module 120, and an nth (where n is a natural number of 2 or more) power conversion module 130. do. The first power conversion module 110 includes a first AC/DC converter 112, a DC/AC inverter 114, a transformer 116, and a second AC/DC converter 118.

The electric tram line 100 supplies high voltage alternating current or alternating current. For example, the catenary 100 can supply a voltage of 60 Hz and 25 kV.

The plurality of power conversion modules 110, 120, and 130 convert the high alternating current input of 25 kV supplied from the electric tram line 100 into direct current output and output it.

The input terminals of the plurality of power conversion modules 110, 120, and 130 are connected in series to receive input by sharing the alternating current voltage supplied from the tram line 100. This is for the plurality of power conversion modules 110, 120, and 130 to reduce voltage stress caused by the electric tram line 100. In addition, the output terminals of the plurality of power conversion modules 110, 120, and 130 are connected in parallel to share the output current. This is to reduce current stress by dividing the current by 1/n when the plurality of power conversion modules 110, 120, and 130 supply the power required to drive the railway vehicle.

Meanwhile, the first AC/DC converter 112 included in the first power conversion module 110 converts the first AC input, which is the value obtained by dividing the AC input by the number of power conversion modules, into a direct current output. The DC/AC inverter 114 converts the direct current output converted by the first AC/DC converter 112 into a high frequency alternating current voltage. When the high-frequency alternating current voltage of the first AC/DC converter 112 is input to the primary side of the transformer 116, the transformer 116 steps down or boosts the voltage by the turns ratio. The second AC/DC converter 118 converts the alternating current voltage transformed by the transformer 116 into direct current voltage and outputs it.

However, voltage imbalance or current imbalance may occur between n power conversion modules connected in series or parallel within a semiconductor transformer. For example, an imbalance may occur between each power conversion module due to causes such as measurement error of the power conversion module and impedance difference between the power conversion module and the load. Voltage imbalance or current imbalance between power conversion modules causes damage to the power conversion module. Furthermore, if one power conversion module is damaged, the remaining power conversion modules must bear the power of the damaged power conversion module instead, so imbalance between power conversion modules may damage all power conversion modules.

Furthermore, while the existing winding transformer is simply composed of an iron core and windings, the semiconductor transformer is composed of a number of components such as a power conversion element and a controller, so there is a disadvantage in terms of reliability. In other words, the reliability of a semiconductor transformer may be lower than that of a winding transformer due to failure of various components within the semiconductor transformer. In particular, controller failures occur more frequently than other component failures and may affect other components.

The main purpose of embodiments of the present invention is to provide a method and device for controlling a semiconductor transformer to prevent damage to the semiconductor transformer due to voltage imbalance or current imbalance between power conversion modules.

Other embodiments of the present invention provide a control method and device for a semiconductor transformer to prevent the reliability of the semiconductor transformer from being reduced due to failure of the module controller that controls the power conversion module within the semiconductor transformer or failure of the power conversion element. There is a purpose to doing it.

According to one aspect of the present invention, in the control device of a semiconductor transformer including a plurality of modules, - the module includes an AC/DC converter, a DC link unit, and a DC/DC converter -, a plurality of AC/DC converters a plurality of module controllers that generate first switching signals to control switches included in; and a voter that controls the plurality of AC/DC converters using signals synchronized from the first switching signals. Provides a control device including.

According to another aspect of the present embodiment, in a method of controlling a semiconductor transformer including a plurality of modules, - the module includes an AC/DC converter and a DC/DC converter -, a switch included in the plurality of AC/DC converters generating first switching signals that control identifying a synchronized signal from the first switching signals; and controlling the plurality of AC/DC converters using the synchronized signal.

As described above, according to an embodiment of the present invention, damage to the semiconductor transformer due to voltage imbalance or current imbalance between power conversion modules can be prevented.

According to another embodiment of the present invention, it is possible to prevent the reliability of the semiconductor transformer from being reduced due to failure of the module controller that controls the power conversion module within the semiconductor transformer or failure of the power conversion element.

Figure 1 is a diagram illustrating a semiconductor transformer applied to a railroad vehicle.
Figure 2 is a diagram showing a power conversion module and module controller of a semiconductor transformer according to an embodiment of the present invention.
Figure 3 is a diagram illustrating a boater according to an embodiment of the present invention.
Figure 4 is a diagram illustrating a module controller that controls a first AC/DC converter according to an embodiment of the present invention.
Figure 5 is a diagram illustrating a module controller that controls a DC/DC converter according to an embodiment of the present invention.
Figure 6 is a diagram showing a process for generating a balance compensation signal according to an embodiment of the present invention.
Figure 7 is a diagram showing a process for generating a pulsation compensation signal according to an embodiment of the present invention.
Figure 8 is a configuration diagram of a control device for a semiconductor transformer according to an embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail through illustrative drawings. When adding reference numerals to components in each drawing, it should be noted that identical components are given the same reference numerals as much as possible even if they are shown in different drawings. Additionally, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description will be omitted.

Additionally, when describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only used to distinguish the component from other components, and the nature, sequence, or order of the component is not limited by the term. Throughout the specification, when a part is said to 'include' or 'have' a certain component, this means that it does not exclude other components but may further include other components, unless specifically stated to the contrary. . Additionally, terms such as 'unit' and 'module' used in the specification refer to a unit that processes at least one function or operation, and may be implemented through hardware, software, or a combination of hardware and software.

The control method and control device according to an embodiment of the present invention can be applied to a semiconductor transformer connected to a distribution network or a semiconductor transformer applied to a power supply device for a railroad vehicle.

Figure 2 is a diagram showing a power conversion module and module controller of a semiconductor transformer according to an embodiment of the present invention.

Referring to FIG. 2, the power conversion module 20 includes a bypass unit 200, a first AC/DC converter 210, a first DC link 220, a DC/DC converter 230, and a second DC link. Includes (240). The DC/DC converter 230 includes a DC/AC inverter 232, transformers 234-1 and 234-2, and a second AC/DC converter 236.

The power conversion module 20 shown in FIG. 2 illustrates one of a plurality of power conversion modules included in a semiconductor transformer. Therefore, the following description can be equally applied to a plurality of power conversion modules in a semiconductor transformer. Additionally, the circuit elements shown in FIG. 2 are merely examples and may have various modifications to provide functions described later.

The power conversion module 20 receives alternating current input from a power device such as a distribution network or electric tram line 100, converts the alternating current input into direct current output, and provides the converted direct current output to other devices.

Hereinafter, the power conversion module 20 will be described as receiving alternating current voltage, converting the alternating voltage into direct current voltage, and outputting it. At this time, the explanation implies that alternating current is also converted according to the conversion of alternating voltage.

The AC input voltage of the power conversion module 20 is the output voltage of the power supply divided by the number of power conversion modules in the semiconductor transformer. For example, when the output voltage V _s of the power device and the number n of power conversion modules are given, the alternating current input voltage of the power conversion module 20 is V _in =V _s /n.

The bypass unit 200 transfers the alternating current input voltage of the power conversion module 20 to the first AC/DC converter 210. The bypass unit 200 may block the alternating current input voltage of the power conversion module 20 as needed.

The first AC/DC converter 210 converts the alternating current input voltage of the power conversion module 20 received from the bypass unit 200 into direct current voltage using a plurality of switching elements. The converted direct current voltage is applied to the first DC link 220. However, the output voltage of the first AC/DC converter 210 is a voltage containing an alternating current component rather than a complete direct current voltage.

The first DC link 220 is connected to the output terminal of the first AC/DC converter 210 and removes the alternating current component of the output voltage converted by the first AC/DC converter 210. In other words, the first DC link 220 stores energy in the form of direct current voltage. To this end, the first DC link 220 includes at least one series capacitor.

The first AC/DC converter 210 may be formed as an integrated structure with the first DC link 220 and convert the alternating current input voltage of the power conversion module 20 into direct current voltage. That is, the output voltage of the first AC/DC converter 210 may be the input voltage of the first DC link 220.

Meanwhile, the first DC link 220 may include a plurality of resistance elements to filter the output voltage of the first AC/DC converter 210. Each resistor element is connected in parallel to a capacitor. In FIG. 2, the first DC link 220 includes four capacitors, and a resistance element may be connected in parallel for each capacitor.

The DC/DC converter 230 receives the direct current voltage of the first DC link 220, adjusts the magnitude of the direct current voltage of the first DC link 220, and outputs it.

Specifically, the DC/AC inverter 232 converts the direct current voltage of the first DC link 220 into alternating current voltage using switching elements.

Transformers 234-1 and 234-2 adjust the magnitude of the converted alternating current voltage. Here, the transformers 234-1 and 234-2 may be high-frequency transformers.

The transformers 234-1 and 234-2 may be configured as multi-winding high-frequency transformers to share magnetic circuits between power conversion modules. When the load is reduced, the control device of the semiconductor transformer can increase energy conversion efficiency by operating only some of the power conversion modules.

The second AC/DC converter 236 converts the scaled alternating current voltage into direct current voltage using switching elements.

The DC voltage whose size is adjusted by the DC/DC converter 230 is applied to the second DC link 240. However, the output voltage of the DC/DC converter 230 is a voltage containing an alternating current component rather than a complete direct current voltage. The second DC link 240 is connected to the output terminal of the DC/DC converter 230 and removes the alternating current component of the output voltage converted by the DC/DC converter 230. In other words, the second DC link 240 stores energy in the form of direct current voltage. To this end, the second DC link 240 includes at least one series capacitor.

Meanwhile, the first DC link 220, DC/DC converter 230, and second DC link 240 may be composed of a plurality of subgroups. In Figure 2, the first DC link 220, DC/DC converter 230, and second DC link 240 are composed of two subgroups. The two subgroups are divided into an upper subgroup and a lower subgroup and are connected in parallel to each other. This is called a 2-level system. The number of subgroups can be set in various ways, and devices can be configured differently depending on the number of subgroups. If it is composed of a 3-level system, it may have a 3-level NPC (Neutral-Point-Clamped) structure.

A plurality of subgroups share the output voltage of the first AC/DC converter 210 by the number of subgroups. Since a plurality of subgroups share voltage, each subgroup can use devices with low breakdown voltage. In other words, the size of the input of the semiconductor transformer is divided by the number of power conversion modules, and the size of the input of the power conversion module is divided by the number of subgroups.

The power conversion module 20 may further include a sensor unit. The sensor unit includes a sensor unit that measures the voltage of the first DC link 220 and a sensor unit that measures the voltage of the second DC link 240. The sensor unit that measures the voltage of the first DC link 220 measures the voltage at both ends of at least one capacitor in the first DC link 220. The sensor unit that measures the voltage of the second DC link 240 measures the voltage at both ends of at least one capacitor in the second DC link 240.

Components within the power conversion module 20 may be configured in a half-bridge form, as shown in FIG. 2. Components within the power conversion module 20 may transmit energy in both directions through a half-bridge structure. That is, the power conversion module 20 can receive power from a load and transmit power to an external power supply device.

Meanwhile, the module controller 30 controls switching elements included in the power conversion module 20. The module controller 30 can control the switching elements by generating switching signals that control the switching elements. The module controller 30 generates switching signals using values measured at various points within the power conversion module 20. This module controller 30 may be a digital controller.

At this time, the module controller 30 may malfunction or a failure of the module controller 30 may occur. Alternatively, the module controller 30 may not be able to generate a switching signal due to voltage and current measurement errors within the power conversion module 20. This becomes a factor that reduces the operational reliability of the semiconductor transformer.

Figure 3 is a diagram illustrating a boater according to an embodiment of the present invention.

Referring to FIG. 3, according to an embodiment of the present invention, a control device for controlling a semiconductor transformer includes a plurality of module controllers 300 and 302 and a voter 310. The plurality of module controllers 300 and 302 include a first module controller 300 and an nth (n is a natural number of 2 or more) module controller 302. In FIG. 3, the plurality of AC/DC converters 320 and 322 refer to AC/DC converters located at the input terminal of each power conversion module.

A plurality of module controllers 300 and 302 generate switching signals that control switching elements within the power conversion modules using measured values within the power conversion modules. That is, the plurality of module controllers 300 and 302 can control switching elements in the power conversion modules using switching signals.

At this time, the plurality of module controllers 300 and 302 may generate switching signals at different times. That is, the plurality of module controllers 300 and 302 may not be synchronized with each other. Additionally, if some of the plurality of module controllers 300 and 302 fail or fail to generate a switching signal, the power conversion modules controlled by some module controllers cannot perform the power conversion function. This becomes a factor that reduces the reliability of the semiconductor transformer.

The control device according to an embodiment of the present invention can solve the above-described problem by using the boater 310. The voter (310) is a component that operates as a multiplexer or synchronizer.

First, the plurality of module controllers 300 and 302 transmit switching signals to the voter 310. The plurality of module controllers 300 and 302 do not directly transmit the switching signals to the plurality of AC/DC converters 320 and 3220, but transmit them to the voter 310.

The voter 310 receives switching signals from a plurality of module controllers 300 and 302 and controls a plurality of AC/DC converters 320 and 322 using signals synchronized from the switching signals.

Specifically, the voter 310 receives switching signals from a plurality of module controllers 300 and 302. The voter 310 selects a switching signal received from one module controller among the received switching signals. The selected switching signal becomes a synchronized signal. At this time, the voter 310 can select a switching signal using the signal selection logic 312, or can randomly select a switching signal. The voter 310 controls the plurality of AC/DC converters 320 and 322 by equally transmitting the selected switching signal to the switch elements included in the plurality of AC/DC converters 320 and 322.

Due to differences between the switching signal generation times of the plurality of module controllers 300 and 302, even if the plurality of module controllers 300 and 302 are in an asynchronous state, the voter 310 is connected to the plurality of module controllers 300 and 302. Switching signals generated by can be synchronized. The boater 310 can also synchronize the operations of the plurality of AC/DC converters 320 and 322 using the synchronized signal.

Furthermore, even if one of the plurality of module controllers 300 and 302 fails, all of the plurality of AC/DC converters 320 and 322 can be operated by using the switching signal received from the remaining module controllers. . Through the multiplexer operation, the voter 310 can prevent the reliability of the semiconductor transformer from being reduced due to a failure of the module controller.

Additionally, to improve the reliability of the voter 310, the signal selection logic 312 of the voter 310 may be composed of a single device, such as an Erasable Programmable Logic Device (EPLD) or a Field-Programmable Gate Array (FPGA).

Figure 4 is a diagram illustrating a module controller that controls a first AC/DC converter according to an embodiment of the present invention.

Referring to FIG. 4, the module controller receives the input voltage value and input current value input to the power conversion module, generates a switching signal to control the first AC/DC converter, and sends the switching signal to the voter 310. send. In Figure 4, the first AC/DC converter refers to the AC/DC converter located at the input terminal of the power conversion module. For this purpose, the module controller includes an all-pass filter 400, an αβ-to-dq converter 410, a phase-locked loop 420, a voltage controller 430, a current controller 440, and a dq-to-αβ converter 450. ) can be used.

The input voltage of the power conversion module is V _ac , and the input current is I _ac . At this time, information about the input voltage and input current is measured by the sensor unit. The measured input voltage and input current are one-phase values.

The input voltage and input current of the power conversion module are filtered by an all-pass filter (400). Specifically, the input voltage and input current of the power conversion module are converted to values on the αβ coordinate system with a 90-degree phase delay from each other by the all-pass filter 400. That is, the input voltage and input current are converted into αβ signals.

The αβ signal is converted into a dq signal by the αβ-to-dq converter 410. The αβ-to-dq converter 410 converts the input voltage and input current expressed in the αβ coordinate system into the dq coordinate system. The dq signal represents the direct current component of the input voltage and input current.

Due to the nature of dq conversion, when the phases match, one of the dq axes becomes 0 and the other represents the maximum value of the input. Using the characteristics of dq conversion, the phase locked loop 420 can extract phase information of the input voltage and input current. The extracted phase information is used for conversion of the αβ-to-dq converter 410 and the dq-to-αβ converter 450.

Meanwhile, the voltage controller 430 is a controller for maintaining the output voltage of the first AC/DC converter constant. The voltage controller 430 uses the output voltage and output voltage reference of the first AC/DC converter to provide an input current command ( ) can be created. Specifically, the voltage controller 430 uses the measured output voltage (V _dc ) of the first AC/DC converter as an output voltage command ( ), calculate the voltage error. The voltage controller 430 generates an input current command of the first AC/DC converter by applying proportional integral (PI) control to the voltage error.

Meanwhile, in this specification, proportional gain control can be changed to various control methods such as differential gain control, integral gain control, proportional-integral control, proportional = derivative control, and proportional-integral-derivative control.

The current controller 440 is a controller for maintaining the input current of the first AC/DC converter constant. The current controller 440 uses the dq component of the input current of the first AC/DC converter and the input current command calculated by the voltage controller 430 to provide an input voltage command ( ) can be created.

The generated input voltage command is added to the dq component of the input voltage and then converted into an αβ signal by the dq-to-αβ converter 450. The αβ signal becomes a switching signal through pulse-width modulation (PWM). For example, a switching signal generator can generate a switching signal by applying pulse width modulation to the αβ signal and the triangle wave. The generated switching signal is transmitted to the voter 310.

Figure 5 is a diagram illustrating a module controller that controls a DC/DC converter according to an embodiment of the present invention.

Referring to FIG. 5, the module controller includes a voltage controller 500, a current controller 510, and a signal generator 520. The module controller controls the output voltage (V _out ) of the power conversion module and the output voltage command ( ), the balanced compensation signal (V _bal ), the output current (I _out ), and the pulsation compensation signal (V _comp ), to generate a switching signal for the DC/DC converter.

The module controller stabilizes the direct current output voltage of the power conversion module and maintains balance between the outputs of the plurality of power conversion modules. To this end, the module controller ensures that the load current of the semiconductor transformer is evenly distributed to the power conversion modules.

Specifically, the voltage controller 500 calculates the output voltage error by subtracting the output voltage command of the DC/DC converter by the measured output voltage. The voltage controller 500 compensates for the imbalance in the output current by adding a balance compensation signal to the output voltage error. Here, the balance compensation signal is a signal to resolve the imbalance between the output currents of the power conversion modules.

The voltage controller 500 performs PI control on the output voltage command, the balanced compensation signal, and the output voltage, that is, the compensated output voltage error, thereby controlling the output current command of the DC/DC converter ( ) is created.

The current controller 510 calculates the output current error by subtracting the output current command by the measured output current. The current controller 510 may generate a voltage command by performing PI control on the output current error. The generated voltage command is combined with the pulsation compensation signal and then becomes a switching signal by the signal generator 520. Here, the pulsation compensation signal is a signal for removing pulsations occurring in the output voltage of the first AC/DC converter and the output current of the power conversion module.

In this way, the module controller can use the balance compensation signal and the pulsation compensation signal to resolve the imbalance between the power conversion modules and remove the pulsation.

The module controller may use at least one of a balanced compensation signal or a pulsation compensation signal.

Figure 6 is a diagram showing a process for generating a balance compensation signal according to an embodiment of the present invention.

Referring to FIG. 6, the balance compensation signal (V _bal ) may be generated by a module controller.

First, the module controller passes the measured output voltage (I _out ) of the power conversion module through the first low-pass filter (600). Likewise, the module controller passes the load current (I _load ) of the semiconductor transformer through the second low-pass filter 610. The first low-pass filter 600 and the second low-pass filter 610 are used to remove noise included in the output voltage of the power conversion module and the load current of the semiconductor transformer.

The module controller uses the divider 620 to divide the filtered load current value by the number of power conversion modules. The divided load current becomes the reference output current of the power conversion module. In other words, the reference output current is the current that each power conversion module must output.

The module controller calculates the output current error based on the difference between the reference output current and the measured output current. The module controller can use the output current error to generate a balanced compensation signal.

According to one embodiment of the present invention, the module controller may use the dead zone 630 to generate a balance compensation signal only when the output current error is greater than a preset value. That is, the dead zone 630 does not output when the output current error is less than a preset value.

If the output current error is greater than the preset value, the module controller adjusts the size of the output current error by the compensation gain 640. Afterwards, the module controller converts the adjusted output current error into a balanced compensation signal.

The balanced compensation signal generated through the above-described process is used to generate the switching signal of the DC/DC converter and ensures that the current between each module is equally distributed.

Meanwhile, at least one of the low-pass filters 600 and 610, the dead zone 630, or the compensation gain 640 may be omitted.

Figure 7 is a diagram showing a process for generating a pulsation compensation signal according to an embodiment of the present invention.

Referring to FIG. 7, the balance compensation signal (V _bal ) may be generated by a module controller. Hereinafter, the balanced compensation signal will be described as being generated based on the input voltage of the DC/DC converter. The balanced compensation signal is intended to remove the pulsating voltage occurring at the output stage of the first AC/DC converter, but since the output voltage of the first AC/DC converter is the same as the input voltage of the DC/DC converter, the input voltage of the DC/DC converter The explanation is based on voltage.

First, the module controller passes the input voltage (V _dc ) of the DC/DC converter through the first low-pass filter (700). The module controller calculates the input voltage error based on the difference between the filtered input voltage and the input voltage reference. The input voltage error becomes a pulsation signal that occurs at the input terminal of the DC/DC converter. The pulsating voltage has a low frequency of 100 Hz or 120 Hz, which is twice the frequency of 50 Hz or 60 Hz.

Pulsating signals affect the output current (I _out ) of the power conversion module. That is, the pulsation signal generates pulsation in the output current of the power conversion module 20. Furthermore, the size of the pulsation signal has the characteristic of increasing as the size of the output current of the power conversion module increases.

Accordingly, the module controller may generate a pulsation compensation signal based on the input voltage error, but may also generate a pulsation compensation signal based on both the input voltage error and the output current of the power conversion module, considering the characteristics of the pulsation signal. Preferably, using both the input voltage error and the output current is advantageous to eliminate pulsations in the output current.

Below, a process for generating a pulsation compensation signal based on both the input voltage error and the output current of the power conversion module will be described.

The module controller passes the output current of the power conversion module through the second low-pass filter 710. The first low-pass filter 700 and the second low-pass filter 710 are used to remove noise.

The module controller uses the multiplier 720 to multiply the input voltage error of the DC/DC converter and the output current of the power conversion module. The module controller multiplies the multiplication result by the compensation gain (730).

The module controller can correct the phase of the multiplication result using the phase corrector 740. Referring to FIG. 5 , the phase of the voltage command output by the current controller 510 may be delayed by the voltage controller 500 and the current controller 510. To eliminate the phase difference between the delayed voltage command and the pulsation compensation signal, the module controller may use a phase corrector 740.

The module controller can generate a pulsation compensation signal through the above process. The pulsation compensation signal prevents pulsation from occurring in the output current of the power conversion module by removing the pulsation signal occurring at the input terminal of the DC/DC converter.

Figure 8 is a configuration diagram of a control device for a semiconductor transformer according to an embodiment of the present invention.

Referring to FIG. 8 , the control device 80 includes a plurality of module controllers 800, 810, and 820 and a boater 830. The number of module controllers 800, 810, and 820 can be set in various ways. The power conversion module that is subject to control includes an AC/DC converter, a DC link unit, and a DC/DC converter. Here, the DC link unit includes an input DC link and an output DC link.

The plurality of module controllers 800, 810, and 820 generate first switching signals that control switches included in the plurality of AC/DC converters.

The voter 830 controls a plurality of AC/DC converters using signals synchronized from the first switching signals.

According to one embodiment of the present invention, one of the first switching signals is selected as the synchronized signal.

According to one embodiment of the present invention, whether the plurality of module controllers are broken is determined depending on whether first switching signals are received from the plurality of module controllers. If the first switching signal is not received from some of the plurality of module controllers, the voter 830 determines that the corresponding module controller is broken.

Meanwhile, the plurality of module controllers 800, 810, and 820 may generate second switching signals that control switches included in the DC/DC converter.

Figure 9 is a configuration diagram of a module controller according to an embodiment of the present invention.

Referring to FIG. 9, the module controller 90 includes a calculation unit 900, a generation unit 910, and a control unit 920.

According to one embodiment of the present invention, the calculation unit 900 calculates the reference output current based on the load current of the semiconductor transformer and the number of modules. The generator 910 generates a balanced compensation signal based on the reference output current and the output current of one module. The generator 910 generates second switching signals that control switches included in the DC/DC converter of the module based on the balance compensation signal. The control unit 920 controls the DC/DC converter using second switching signals.

According to one embodiment of the present invention, the balance compensation signal may be generated when the difference between the reference output current and the output current of the module is greater than a preset value.

According to another embodiment of the present invention, the generator 910 generates a pulsation signal based on the input voltage and input voltage command of the DC/DC converter of one module. The generator 910 generates second switching signals that control switches included in the DC/DC converter based on the pulsation signal. The control unit 920 controls the DC/DC converter using second switching signals.

According to another embodiment of the present invention, the generator 910 may generate a pulsation compensation signal based on the pulsation signal and the output current of the module, and generate second switching signals using the pulsation compensation signal.

According to another embodiment of the present invention, the calculation unit 900 calculates the reference output current based on the load current of the semiconductor transformer and the number of modules.

The generator 910 generates a balanced compensation signal based on the reference output current and the output current of one module. The generator 910 generates a pulsation signal based on the input voltage of the DC/DC converter of the module and the input voltage command. The generator 910 generates a pulsation compensation signal based on the pulsation signal and the output current of the module. The generator 910 generates an output current command of the module by applying proportional gain control to the output voltage command, output voltage, and balance compensation signal of the module. The generator 910 generates a new voltage command by applying proportional gain control to the output current command and the output current. The generator 910 generates a second switching signal by applying pulse width modulation based on the generated voltage command and pulsation compensation signal. The control unit 920 controls the DC/DC converter using second switching signals.

According to one embodiment of the present invention, the module controller 90 may further include a correction unit (not shown) that corrects the phase of the pulsation compensation signal according to the phase of the generated voltage command.

Figure 10 is a diagram illustrating loads to which a control device for a semiconductor transformer according to an embodiment of the present invention is applied.

Referring to FIG. 10, when the AC input power 1000 is a one-phase extra high voltage supplied by the distribution network, the DC output terminal of the semiconductor transformer 1010 uses a DC distribution network (Low Voltage Direct Current, LVDC) or a common DC bus. can be formed. The output terminal of the semiconductor transformer 1010 may be connected to various devices.

The semiconductor transformer 1010 can be used as a power generation device and a load supply device. For example, when the output terminal of the semiconductor transformer 1010 is connected to a commercially available 1-phase or 3-phase uninterruptible power supply device 1020, power can be supplied to the 1-phase or 3-phase AC load 1022. The output terminal of the semiconductor transformer 1010 may be connected to a charging device 1030 that can charge the electric vehicle 1032. The output terminal of the semiconductor transformer 1010 may be connected to a power conversion device 1040 that can generate power or charge and discharge using a solar cell or storage battery 1042. The output terminal of the semiconductor transformer 1010 may be connected to an inverter device 1050 for driving an electric motor 1052 applied to general industry or railway vehicles.

In this application, the advantage of the semiconductor transformer 1010 over the existing winding transformer is that it provides a common DC bus, making it possible to eliminate the AC/DC conversion device, that is, the rectifier, that devices such as existing charging devices and inverters have in common. It is possible. Furthermore, the semiconductor transformer 1010 can transmit power generated during regenerative operation of the electric motor 1052 to other devices. In addition, since the semiconductor transformer 1010 can transmit power back, it can provide an effective conversion device configuration even in connection with renewable power sources such as solar power generation.

In the above-described drawings, each process is described as being sequentially executed, but this is merely an illustrative explanation of the technical idea of an embodiment of the present invention. In other words, a person skilled in the art to which an embodiment of the present invention pertains can change the order described in the drawings or perform one or more of the processes without departing from the essential characteristics of an embodiment of the present invention. Since various modifications and variations can be applied by executing in parallel, the drawings are not limited to a time series order.

Meanwhile, the processes shown in the drawings can be implemented as computer-readable codes on a computer-readable recording medium. Computer-readable recording media include all types of recording devices that store data that can be read by a computer system. In other words, such computer-readable recording media include non-transitory media such as ROM, RAM, CD-ROM, magnetic tape, floppy disk, and optical data storage devices. Additionally, computer-readable recording media can be distributed across networked computer systems so that computer-readable code can be stored and executed in a distributed manner.

Additionally, the components of the present invention may use integrated circuit structures such as memory, processor, logic circuit, look-up table, etc. These integrated circuit structures execute each function described herein through control of one or more microprocessors or other control devices. Additionally, the components of the present invention may be specifically implemented by a program or portion of code that includes one or more executable instructions for performing specific logical functions and is executed by one or more microprocessors or other control devices. Additionally, the components of the present invention may include or be implemented by a central processing unit (CPU), a microprocessor, etc. that perform their respective functions. Additionally, the components of the present invention may store instructions executed by one or more processors in one or more memories.

The above description is merely an illustrative explanation of the technical idea of the present embodiment, and those skilled in the art will be able to make various modifications and variations without departing from the essential characteristics of the present embodiment. Accordingly, the present embodiments are not intended to limit the technical idea of the present embodiment, but rather to explain it, and the scope of the technical idea of the present embodiment is not limited by these examples. The scope of protection of this embodiment should be interpreted in accordance with the claims below, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of rights of this embodiment.

900: Calculation unit
910: Generation unit
920: Control unit

Claims (18)

A control device for a semiconductor transformer comprising a plurality of modules, wherein the modules include an AC/DC converter, a DC link unit, and a DC/DC converter,
A plurality of module controllers that generate first switching signals at different times to control switches included in a plurality of AC/DC converters; and
a voter that controls the plurality of AC/DC converters using signals synchronized from the first switching signals;
Including,
The boater,
A control device that selects one of the first switching signals as the synchronized signal. delete According to paragraph 1,
The module controller is,
a calculation unit that calculates a reference output current based on the load current of the semiconductor transformer and the number of modules;
Generating a balanced compensation signal based on the reference output current and the output current of one module, and generating second switching signals for controlling switches included in the DC/DC converter of the module based on the balanced compensation signal. wealth; and
A control unit that controls the DC/DC converter using the second switching signals
A control device comprising a. According to paragraph 3,
The balance compensation signal is,
A control device that is generated when the difference between the reference output current and the output current of the module is greater than a preset value. According to paragraph 1,
The module controller is,
Generating a pulsation signal based on the input voltage and input voltage command of a DC/DC converter of one module, and generating second switching signals for controlling switches included in the DC/DC converter based on the pulsation signal. wealth; and
A control unit that controls the DC/DC converter using the second switching signals
A control device comprising a. According to clause 5,
The generating unit,
A control device for generating a pulsation compensation signal based on the pulsation signal and the output current of the module, and generating the second switching signals using the pulsation compensation signal. According to paragraph 1,
The boater,
A control device that determines whether the plurality of module controllers are broken depending on whether first switching signals are received from the plurality of module controllers. According to paragraph 1,
The module controller is,
a calculation unit that calculates a reference output current based on the load current of the semiconductor transformer and the number of modules; and
Generate a balanced compensation signal based on the reference output current and the output current of one module, generate a pulsation signal based on an input voltage of a DC/DC converter of the module and an input voltage command, and generate the pulsation signal and the module. Generate a pulsation compensation signal based on the output current of the module, apply proportional gain control to the output voltage command, output voltage, and the balance compensation signal of the module to generate an output current command of the module, and generate the output current command and output A generator that generates a new voltage command by applying proportional gain control to the current and generates a second switching signal by applying pulse width modulation based on the generated voltage command and the pulsation compensation signal.
A control device comprising a. According to clause 8,
The module controller is,
A correction unit that corrects the phase of the pulsation compensation signal according to the phase of the generated voltage command.
A control device further comprising: A method of controlling a semiconductor transformer including a plurality of modules, wherein the modules include an AC/DC converter and a DC/DC converter.
Generating first switching signals at different times to control switches included in a plurality of AC/DC converters;
identifying a synchronized signal from the first switching signals; and
Controlling the plurality of AC/DC converters using the synchronized signal
Including,
The step of identifying the synchronized signal is,
A control method comprising selecting one of the first switching signals as the synchronized signal. delete According to clause 10,
calculating a reference output current based on the load current of the semiconductor transformer and the number of modules;
generating a balanced compensation signal based on the reference output current and the output current of one module;
generating second switching signals to control switches included in the DC/DC converter of the module based on the balance compensation signal; and
Controlling the DC/DC converter using the second switching signals
A control method further comprising: According to clause 12,
The balance compensation signal is,
A control method that is generated when the difference between the reference output current and the output current of the module is greater than a preset value. According to clause 10,
Generating a pulsation signal based on the input voltage of the DC/DC converter of one module and the input voltage command;
generating second switching signals to control switches included in the DC/DC converter of the module based on the pulsation signal; and
Controlling the DC/DC converter using the second switching signals
A control method further comprising: According to clause 14,
Generating the second switching signals includes:
generating a pulsation compensation signal based on the pulsation signal and the output current of the module; and
A control method comprising generating the second switching signals using the pulsation compensation signal. According to clause 10,
The first switching signals are generated using a plurality of module controllers,
the synchronized signal is identified from the first switching signals using a voter,
Determining whether the plurality of module controllers are broken depending on whether the first switching signals are received from the boater
A control method further comprising: According to clause 10,
calculating a reference output current based on the load current of the semiconductor transformer and the number of modules;
generating a balanced compensation signal based on the reference output current and the output current of one module;
Generating a pulsation signal based on the input voltage of the DC/DC converter of one module and the input voltage command;
generating a pulsation compensation signal based on the pulsation signal and the output current of the module;
generating an output current command of the module by applying proportional gain control to the output voltage command, the output voltage, and the balance compensation signal of the module;
generating a new voltage command by applying proportional gain control to the output current command and the output current; and
Generating second switching signals for controlling switches included in the DC/DC converter of the module by applying pulse width modulation based on the generated voltage command and the pulsation compensation signal.
A control method further comprising: According to clause 17,
Correcting the phase of the pulsation compensation signal according to the phase of the generated voltage command.
A control method further comprising:

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