KR20230059514A - Device for lmplementation of Parallel Converter System for Parameter Estimation and Continuous Operation - Google Patents

Abstract

The present invention relates to a device for estimating an internal parameter of a capacitor connected to an electrical device while the electrical device is operating, and more particularly, after constructing a parallel connection by connecting inputs and outputs of three or more electrical devices, a diagnostic device, The present invention relates to a method of estimating a capacitor internal parameter while maintaining a constant load current by setting a canceling device and a general device so that the canceling device compensates for the distortion of the load current generated when the diagnostic device estimates the internal parameter of the capacitor.

Description

Parallel converter system implementation device for converter parameter estimation and continuous operation {Device for lmplementation of Parallel Converter System for Parameter Estimation and Continuous Operation}

The present embodiment relates to a method for estimating an internal parameter of a capacitor, which is a key factor in aging of a power converter, by injecting a disturbance signal into a power converter connected in parallel. In particular, unlike the existing method, it relates to a method for accurately measuring capacitor internal parameters without affecting the load by injecting a cancellation signal into another power converter connected in parallel so that the load voltage or current is not distorted by the disturbance signal. .

A DC-DC (direct current-to-direct current) converter is a power conversion device that converts direct current into direct current, and serves to increase or decrease the output voltage from the input voltage. DC-DC converters have recently been used in various applications such as electric vehicles, solar power generation, mobile devices, and home appliances, and the DC-DC converter market is expected to reach $22.4 billion worldwide in 2025.

As DC-DC (direct current-to-direct current) converters are used in various fields, safety-related restrictions are becoming stricter. -Many studies are being conducted to improve the reliability of DC converters. In particular, the demand for technology related to the status monitoring of DC-DC converters, which can prevent accidents in advance, is explosively increasing.

A DC-DC (DC-DC) converter converts a direct current input voltage into a high frequency using a power semiconductor switch element, and then generates a direct current output voltage using a filter composed of an inductor and a capacitor. In particular, the capacitor has a DC-DC converter. While the DC converter is operating, the high-frequency voltage generated by the power semiconductor switch is continuously applied. Therefore, the capacitor is vulnerable to deterioration among DC-DC converter elements and has a short lifespan, and deterioration causes large fluctuations in ESR (Equivalent Series Resistor, Equivalent Series Resistance) and capacitance values, which are internal parameters. About 30% of DC-DC converter failures are caused by capacitor aging, and when a capacitor fails due to aging, the corresponding capacitor is often short-circuited. If the capacitor is short-circuited, the DC-DC converter is short-circuited, resulting in a short circuit or fire, or the accident may spread to external systems connected to the DC-DC converter. To prevent accidents in advance, technology for estimating capacitor aging is required. .

There are offline measurement and online measurement methods for estimating capacitor aging. Offline measurement is a method of measuring a capacitor when a power conversion device such as a DC-DC (direct current-to-direct current) converter is not operating, and is effective in the field where the power conversion device periodically stops operating. Online measurement is a method of measuring without separating a capacitor from the power converter while the power converter is operating, and has the advantage of not having to stop the power converter during measurement. The method of estimating the aging of a capacitor by estimating the ESR (Equivalent Series Resistor) value and the capacitance value, which are internal parameters of the capacitor, is suitable for online measurement methods, and many studies have been conducted.

“Application No. 10-2001-0011750, Method for Monitoring DC Capacitor Aging of Inverters”, filed in Korea on March 7, 2001 and announced on March 9, 2004, and filed in Korea on July 17, 2015 The patent “Application No. 10-2015-0101494, Apparatus for Diagnosing Aging of DC Link Capacitors in Bidirectional Hybrid Solar PCS” published on February 1, 2016 is an online measurement method that measures capacitor ripple during inverter or solar PCS operation. ) The voltage is measured to calculate the ESR (Equivalent Series Resistor) value, which is an internal parameter of the capacitor. The disadvantage is that it is difficult to accurately measure the ripple voltage due to the increase in ESR value by distinguishing it from noise. In order to overcome this problem, in previous studies, a disturbance signal was injected into the control signal that controls the power converter, and the voltage or current of the capacitor reacting to the disturbance signal was measured to obtain a transfer function, and based on the obtained transfer function, the ESR value and capacitance The internal parameters of the capacitor, such as the value, were estimated, and aging was estimated based on this. There is also a limitation in these existing studies. The method of injecting a perturbation signal as a disturbance signal causes vibration in the output voltage or output current of the power converter due to the injected perturbation signal, resulting in power loss and power quality degradation. There is a problem with falling. In addition, when the load current or voltage demand value fluctuates while injecting the perturbation signal, the power converter changes the voltage or current operating point of the power converter to satisfy the changed load demand value. In this case, the capacitor internal parameter using the perturbation signal There is a problem with poor estimation accuracy. In the method of injecting a step function signal as a disturbance signal, the output voltage and output current of the power converter are changed due to the injected step function signal, so that the output required by the load cannot be accurately produced, so the precise output of the power converter It is virtually impossible to apply in this demanding field.

Against this background, the purpose of this embodiment is to inject a disturbance signal into the power conversion device in order to estimate the internal parameters of the capacitor of the power conversion device, and then to measure the response of the capacitor due to the disturbance signal, while measuring the response of the capacitor due to the disturbance signal. It is to provide a method for the power conversion device to supply the voltage or current required by the load and maintain operation without receiving the load.

In order to achieve the above object, one embodiment configures the parallel connection for three or more electric devices (110, 120, 130) that operate and configure the parallel connection by connecting the input terminals and the output terminals respectively. a measurement unit 140 for obtaining time-series data for the currents 112, 122, and 132 of the capacitors connected to the output terminals of individual electrical devices that a control unit 150 controlling individual electrical devices constituting the parallel connection; an estimator 160 estimating an aging degree by estimating an internal parameter of the capacitor; It provides a parallel converter system implementation device for converter parameter estimation and continuous operation including a.

The measurement unit 140 includes a measurement circuit 141 installed in the capacitors 111, 121, and 131 to amplify or reduce the currents 112, 122, and 132 of the capacitors and convert them into voltage signals; a filter 142 for filtering a noise signal of an unnecessary frequency band with respect to the signal output from the measuring circuit; and an ADC (Analog-Digital-Converter) 143 for obtaining time-series data by converting the signal output from the filter into a digital signal. may further include.

The control unit 150 controls the electrical devices 110, 120, and 130 to supply voltage and current required by a load connected to the output terminal of the electrical device operated in parallel, or controls the capacitors 111 and 121. , 131), a disturbance signal may be injected into the electrical devices 110, 120, and 130 constituting the parallel connection.

The estimator 160, when the estimation of the internal parameters of the capacitor starts, uses the disturbance signal output from the control unit 150 and the time-series data obtained by the measurement unit 140 corresponding to the same time point as the disturbance signal. Transfer functions of the capacitors 111, 121, and 131 may be estimated, internal parameters may be estimated through the estimated transfer functions, and aging levels may be estimated through the estimated internal parameters. Operation clocks of the measurement unit 140, the control unit 150, and the estimation unit 160 may be synchronized to match the timing of the time series data and the disturbance signal.

Another embodiment is a method for estimating an internal parameter of a capacitor by a device, wherein an individual electric device constituting a parallel connection for three or more electric devices having an input terminal connected to each other and an output terminal connected to each other to configure a parallel connection is a diagnostic device. , offset device, setting step of setting to a general device; a control step of injecting a diagnosis signal as the disturbance signal into the diagnosis device, injecting a cancellation signal as the disturbance signal into the canceling device, and injecting a general signal into the general device; a measurement step of acquiring first time-series data for the capacitor current of the diagnosis device and obtaining second time-series data for the capacitor current of the canceling device; an estimation step of estimating the degree of aging of the capacitor of the diagnostic device by estimating an internal parameter of the capacitor of the diagnostic device, and estimating the degree of aging of the capacitor of the canceller by estimating an internal parameter of the capacitor of the canceller; It provides a capacitor internal parameter estimation method including. Estimating the internal parameters of the capacitor may be initiated by a timer or by an external signal.

In the setting step, an electric device connected to a capacitor whose internal parameter is to be estimated is set as a diagnostic device, and the internal parameter of the capacitor is estimated by compensating for distortion of the load voltage or current due to the diagnostic signal injected into the diagnostic device. setting the canceling device that serves to prevent the load voltage or current from being distorted, and setting the rest of the electric devices except for the diagnosis device and the canceling device as the general devices; may further include.

The controlling step may include injecting a perturbation signal or a step function signal as the diagnostic signal into the diagnostic device, and when the diagnostic signal is injected into the diagnostic device, the load voltage or current is distorted. generating the canceling signal through calculation and injecting the canceling signal into the canceling device so that the canceling device compensates and maintains the load voltage or current; may further include.

The control step may include supplying voltage or current to the load by the electric device set as the general device when the voltage or current required by the load is changed while estimating the internal parameter of the capacitor; may further include.

In the measuring step, the capacitor current is measured from the moment the diagnostic signal is injected into the diagnostic device until the capacitor current connected to the diagnostic device passes through a transient response and stabilizes in a steady state. measuring the capacitor current from the moment the cancellation signal is injected into the cancellation device until the capacitor current connected to the cancellation device passes through a transient response and stabilizes in a steady state; may further include.

The measuring step may include obtaining the first time series data and the second time series data by amplifying or reducing the capacitor current and converting it into a voltage signal, filtering a noise signal of an unnecessary frequency band, and converting it into a digital signal; may further include.

The measuring step may include ADCs (Analog-Digital-Converters) for acquiring the first time-series data and the second time-series data.

The estimating step may include estimating a transfer function of the capacitor of the diagnostic device using the diagnostic signal and the first time series data, estimating an internal parameter of the capacitor based on the transfer function, and estimating a degree of aging of the capacitor based on the internal parameter. estimating; Estimating a transfer function of the cancellation device capacitor with the cancellation signal and the second time series data, estimating an internal parameter of a diagnostic device capacitor based on the transfer function, and estimating a degree of aging of the capacitor based on the internal parameter step; It can be further included.

In the estimating step, the diagnosis signal and the first time-series data are obtained at the same time to obtain a transfer function of the diagnosis device capacitor, and the cancellation signal and the second time-series data are obtained at the same time to obtain the cancellation device capacitor obtaining a transfer function; may further include.

If there is an aged electrical device, the step of estimating the capacitor parameters may be repeated with the remaining electrical devices without operating the aged electrical device.

As described above, according to the present embodiment, there is an effect of estimating the aging of the capacitor by measuring internal parameters of the capacitor without affecting the load of the power converter while the power converter is operating. In addition, according to this embodiment, by estimating capacitor aging, it is possible to know when to repair or replace the power conversion device in which the corresponding capacitor is used, and accidents caused by aging of the capacitor can be prevented in advance.

1 is a block diagram of an apparatus for estimating internal parameters of a capacitor according to an exemplary embodiment.
2 is a flowchart of a method for estimating internal parameters of a capacitor according to an exemplary embodiment.
3 is a diagram showing an example of estimating internal parameters of a capacitor by injecting a perturbation signal as a disturbance signal into an electric device in a previous study.
4 is a diagram illustrating an example of estimating internal parameters of a capacitor by injecting a perturbation signal into an electric device as a disturbance signal according to an exemplary embodiment.
5 is a diagram showing an example in which a load current is changed when a perturbation signal as a disturbance signal is injected into an electric device in an existing study to estimate an internal parameter of a capacitor.
6 is a diagram illustrating an example in which a load current is changed when a perturbation signal as a disturbance signal is injected into an electric device to estimate an internal parameter of a capacitor according to an embodiment.
7 is a diagram showing an example of estimating internal parameters of a capacitor by injecting a step function signal as a disturbance signal into an electric device in a previous study.
8 is a diagram illustrating an example of estimating an internal parameter of a capacitor by injecting a step function signal into an electric device as a disturbance signal according to an embodiment.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In adding reference numerals to components of each drawing, it should be noted that the same components have the same numerals as much as possible even if they are displayed on different drawings. In addition, 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.

Also, terms such as first, second, A, B, (a), and (b) may be used in describing the components of the present invention. These terms are only used to distinguish the component from other components, and the nature, order, or order of the corresponding component is not limited by the term. When an element is described as being “connected,” “coupled to,” or “connected” to another element, that element is directly connected or connectable to the other element, but there is another element between the elements. It will be understood that elements may be “connected”, “coupled” or “connected”.

1 is a block diagram of an apparatus for estimating internal parameters of a capacitor according to an exemplary embodiment.

Referring to FIG. 1, in the capacitor internal parameter estimating device, input terminals of n (three or more) first electric devices 110, second electric devices 120, and n electric devices 130 are connected to one, A first electric device capacitor 111 is connected to an output terminal of the first electric device 110, a second electric device capacitor 121 is connected to an output terminal of the second electric device 120, and the nth electric device An n-th electric device capacitor 131 is connected to the output terminal of the device 130, and the output terminals of the first electric device 110, the second electric device 120, and the n-th electric device 130 are all one. can be connected to form a parallel connection.

The capacitor internal parameter estimating device includes a measuring unit 140 that obtains time-series data for the n (three or more) capacitor currents 112, 122, and 132; In order to control the n (three or more) electrical devices 110, 120, 130, n (three or more) control signals are transmitted to the n (three or more) electrical devices (110, 120, 130). ) The control unit 150 that transmits to; an estimator 160 for estimating a degree of aging by estimating internal parameters of the n (three or more) capacitors 111, 121, and 131; may further include.

The measuring unit 140 is installed in the n capacitors 111, 121, 131 to amplify or reduce the currents 112, 122, 132 of the n capacitors and convert them into voltage signals; a measuring circuit 141; a filter 142 for filtering noise signals of an unnecessary frequency band with respect to the signal output from the measuring circuit 141; and an ADC 143 converting the signal output from the filter 142 into a digital signal to obtain time-series data. may further include.

The n electric devices including the first electric device 110 , the second electric device 120 , and the n electric device 130 may include a power conversion device. As an example, the electric device may include a photovoltaic device as a power generation device and a power conversion device that converts power generated by the photovoltaic device and supplies it to a load. As another example, the electrical devices may include an energy storage device and a power conversion device that converts power stored in the energy storage device and supplies it to a load.

The n electrical devices including the first electrical device 110, the second electrical device 120, and the n-th electrical device 130 include a switch and chop electric power using the switch. power can be converted in this way. For example, the electrical device may be a buck converter, a boost converter, a flyback converter, a 2-phase or 3-phase inverter, and the like. The n electric devices including the first electric device 110, the second electric device 120, and the n electric device 130 may have a constant control frequency or a control frequency within a certain range. . Here, the control frequency may determine a cycle of chopping power.

The measuring unit 140 may measure the n capacitor currents 112 , 122 , and 132 and store the measured values in a memory as time-series data in a time sequence. The measuring unit 140 may generate time-series data by storing measured values of the n capacitor currents 112, 122, and 132 as they are, or may generate time-series data by filtering or scaling the measured values. there is. The number of n capacitor currents 112 , 122 , and 132 measured by the measurer 140 may be n or more depending on the configuration of the electric device 110 , 120 , and 130 .

The measuring circuit 141 can convert the n capacitor currents 112, 122, and 132 into a voltage form and obtain it, and can amplify or reduce the voltage to an appropriate level as needed.

The filter 142 may filter a noise signal of an unnecessary frequency band with respect to the signal output from the measurement circuit 141 . The signal output by the measurement circuit 141 is first converted into a digital signal through the ADC 143 to obtain time-series data, and then the noise signal of the unnecessary frequency band of the time-series data is removed through the filter 142 implemented in software. can also be filtered.

The ADC 143 converts the signal output from the filter 142 into a digital signal to obtain time-series data. In addition, time-series data may be obtained repeatedly several times during a predetermined time period.

The controller 150 is composed of a digital processor and outputs n number of control signals to control the operation of the n number of electrical devices 110, 120 and 130 through the control signals. When the n electrical devices 110, 120, and 130 are power conversion devices controlled by PWM (Pulse Width Modulation), the control signal output by the control unit 150 may be a PWM signal, and the n electrical devices When 110, 120, and 130 are power conversion devices controlled according to a specific voltage level, the control signal output by the controller 150 may be a voltage signal having a specific value. The control unit 150 controls the n electrical devices 110, 120, and 130 through control signals so that the n electrical devices 110, 120, and 130 can supply the voltage or current required by the load. When estimating internal parameters of the capacitors 111, 121, and 131, the control unit 150 may add a disturbance signal to the control signal and transmit the control signal to the n electrical devices 110, 120, and 130.

The estimator 160 is composed of a digital processor, and when estimating the internal parameters of the n capacitors 111, 121, and 131, the control signal output by the control unit 150 and the measurement unit 140 obtain The transfer function of the capacitor is obtained using the time series data, and the internal parameters of the capacitor and the degree of aging can be estimated using the acquired transfer function.

In order for the estimator 160 to obtain the transfer function of the capacitor, the output time of the control signal output from the control unit 150 may coincide with the acquisition time of the time-series data acquired by the measurement unit 140, For this purpose, operation clocks of the measurement unit 140, the control unit 150, and the estimation unit 160 may be synchronized.

2 is a flowchart of a method for estimating internal parameters of a capacitor according to an exemplary embodiment.

Referring to FIG. 2, the method for estimating internal parameters of a capacitor is a diagnosis device, a canceling device, Setting step of setting as a general device (S210); a control step (S220) of injecting a diagnosis signal as a disturbance signal into the diagnosis device, injecting a cancellation signal as a disturbance signal into the canceling device, and injecting a general signal into the general device; a measuring step (S230) of acquiring time-series data for the capacitor current of the diagnostic device and the capacitor current of the canceling device; An estimation step of estimating internal parameters and aging degree of the capacitor of the diagnostic device using the diagnosis signal and the time-series data and estimating internal parameters and aging degree of the capacitor of the cancellation device using the cancellation signal and the time-series data (S240). ); can include

The capacitor internal parameter estimating method may be started internally, for example, may be periodically generated by a timer, or may be generated by the capacitor internal parameter estimating device when a specific condition is satisfied. The specific condition may be a condition related to capacitor current. As an example, the capacitor internal parameter estimating apparatus may start an internal parameter estimation method when the capacitor current exceeds or falls below a reference value. As another example, the capacitor internal parameter estimating apparatus may calculate a standard deviation of a variation over time from the obtained time-series data of the capacitor current, and start an internal parameter estimation method when the standard deviation is out of a reference range.

The setting step (S210) is a step of classifying and setting the n (three or more) electrical devices constituting the parallel connection into a diagnosis device, a canceling device, and a general device, including a capacitor for which internal parameters are to be estimated. Electrical devices can be set as diagnostic devices. When the diagnosis signal is injected into the diagnosis device as a disturbance signal to estimate the internal parameters of the capacitor, an electrical device that operates to cancel distortion appearing in the load current may be set as the canceling device. In addition, when estimating internal parameters, the electric device that is not set as the diagnosis device or the canceling device may be set as the general device. One or more diagnosis devices may be set according to the configuration of the electrical device, and one or more canceling devices may be set according to the configuration of the electrical device. The general device may not be set according to the configuration of the electric device, or may be set to one or more.

In the control step (S220), a diagnosis signal is sent to the diagnosis device as a disturbance signal, and the diagnosis signal may be a perturbation signal or a step function signal according to a method for estimating a capacitor internal parameter. When the perturbation signal is injected as the diagnosis signal, the current of the capacitor of the diagnostic device may be measured while changing the frequency of the perturbation signal. When the frequency of the perturbation signal is changed, the frequency of the cancellation signal injected into the cancellation device may also be changed, and at this time, the capacitor current of the cancellation device may also be measured. When injecting the step function as the diagnostic signal, the step function may be a unit step function that changes from 0 to 1, a step function that changes from 0 to a specific value other than 1, or a step function that changes to several values It can be a general step function. The canceling signal may be generated and outputted to the canceling device so that the canceling device may compensate for distortion of the load current by the diagnosis device due to the diagnosis signal. The general signal for controlling the general device may maintain the same signal as before the implementation of the internal parameter estimation method. When the load current is changed while estimating the internal parameter of the capacitor, the general signal can be changed and output to the general device so that the general device can supply the changed load current, and the diagnosis signal and the offset signal can be output to the load current and the normal device. Regardless, the same signal can be maintained.

In the measuring step (S230), first time-series data may be obtained by measuring the capacitor current of the diagnostic device, and second time-series data may be obtained by measuring the capacitor current of the canceling device. The diagnostic device current may be measured from the moment the diagnostic signal is injected into the diagnostic device until the capacitor current of the diagnostic device passes through a transient response and is stabilized in a steady state, and the offset signal is The cancellation device capacitor current may be measured from the moment it is injected into the cancellation device until the cancellation device capacitor current passes through a transient response and stabilizes in a steady state. In the measuring step, the diagnostic device and the canceling device capacitor currents are amplified or reduced to convert them into voltage signals, filter noise signals in unnecessary frequency bands, and then convert them into digital signals to obtain time-series data. An ADC (Analog-Digital-Converter) may be further included to obtain .

In the estimating step (S240), transfer functions of the diagnostic device capacitor and the canceling device capacitor are estimated. Internal parameters can be calculated based on the estimated transfer function, and the degree of aging can be estimated based on the calculated internal parameters. A transfer function may be obtained and an internal parameter may be estimated based on first time-series data of a diagnostic signal injected into the diagnostic device and a capacitor current of the diagnostic device. In addition, a transfer function may be obtained and an internal parameter may be estimated based on the second time-series data of the cancellation signal versus the current of the capacitor of the cancellation device. To obtain the transfer function, the diagnosis signal and the first time-series data acquired at the same time point may be used, and the offset signal and the second time-series data obtained at the same time point may be used. To this end, the estimation step (S240), the measurement step (S230), and the control step (S220) may operate in synchronization. In the estimating step (S240), if there is an aged capacitor among the n capacitors connected to the n electrical devices, the electrical devices including the aged capacitors are not operated, and the remaining (n-1) electrical devices The capacitor internal parameter estimation method can be repeated.

The present invention is explained in more detail in contrast to previous studies with the following examples, which are not intended to limit the present invention.

3 is a diagram showing an example of estimating internal parameters of a capacitor by injecting a perturbation signal as a disturbance signal into an electric device in a previous study.

Referring to FIG. 3 , a control signal having a magnitude of c1 is output to the electric device 310 to supply a constant current having a magnitude of c4 to a load connected to an output terminal of the electric device 310 . In order to estimate the internal parameter of the capacitor 320 connected to the output terminal of the electric device 310, when a perturbation signal having a magnitude of c2 is injected into the control signal maintaining the magnitude of c1, the current of the capacitor is the perturbation In response to signal c2, it may vibrate with a magnitude of c3. A transfer function may be obtained using the perturbation signal c2 value and the capacitor current c3 value, an internal parameter of the capacitor may be estimated using the transfer function, and aging of the capacitor may be estimated using the estimated internal parameter. there is. However, due to the value of the perturbation signal c2 injected for estimating the internal parameter of the capacitor, the load current may not maintain a constant value of c4 and may vibrate at a magnitude of c5. Therefore, the power quality of the load is degraded and power loss occurs due to vibration, so that it is practically impossible to apply in fields requiring precise power quality or small power loss. An embodiment for solving this problem is shown in FIG. 4 .

4 is a diagram illustrating an example of estimating internal parameters of a capacitor by injecting a perturbation signal into an electric device as a disturbance signal according to an exemplary embodiment.

Referring to FIG. 4 , the electrical devices 410, 420, and 430 may form a parallel connection. That is, the input terminals of the first electric device 410, the second electric device 420, and the third electric device 430 are all connected to one, and the first electric device capacitor 411 and the second electric device capacitor 421 , The third electric device capacitor 431 is connected to the output terminals of the first electric device 410, the second electric device 420, and the third electric device 430, respectively, and the first electric device 410 After the output terminal of the second electric device 420 and the output terminal of the third electric device 430 are all connected to one another, they can be connected to a load. In one embodiment, for convenience, the electric device and the electric device capacitor are composed of three, but it is preferable to consider that it can be divided into n (n is 3 or more) electric devices and capacitors. Before estimating the internal parameter of the capacitor, the first electric device 410, the second electric device 420, and the third electric device 430 are supplied with a current having a magnitude of d8 to the load connected to the output terminal. A control signal having a magnitude of d1 is transmitted to the device 410, a signal having a magnitude of d4 is transmitted to the second electric device 420, and a control signal having a magnitude of d7 is transmitted to the third electric device 430. signal can be transmitted. When estimating internal parameters of the capacitor starts, an electrical device connected to the capacitor whose internal parameters are to be estimated may be set as a diagnostic device. In one embodiment, the first electric device 410 may be set as a diagnosis device, the second electric device 420 may be set as a canceling device, and the third electric device 430 may be set as a general device. Settings of the diagnosis device, the canceling device, and the general device corresponding to each electric device may be changed. To the first electric device 410 set as a diagnosis device, a perturbation signal having a magnitude of d2 is injected to estimate the internal parameter of the first electric device capacitor 411, and the second electric device set as an offset device A perturbation signal having a magnitude of d5 may be injected into 420. The control signal of the third electric device 430 set as a general device may maintain the size of d7. of the first electric device capacitor 411 by using the perturbation signal having the magnitude of d2 among the control signals of the first electric device 410 set as the diagnostic device and the value d3 of the current 412 of the first electric device capacitor Internal parameters can be estimated. In addition, the internal parameter of the canceller capacitor 421 can be estimated using a perturbation signal having a magnitude of d5 among the control signals of the second electric device 420 and a signal d6 of the current 422 of the second electric device capacitor. there is. Since the second electric device 420 set as a canceling device compensates for the load current distorted by the first electric device 410 set as a diagnosis device, the load current is not distorted while estimating the internal parameter and the internal parameter It can be kept constant as before estimation. Therefore, power loss due to vibration of the load current is prevented, and it can be applied to fields requiring precise power quality or small power loss.

5 is a diagram showing an example in which a load current is changed when a perturbation signal as a disturbance signal is injected into an electric device in an existing study to estimate an internal parameter of a capacitor.

Referring to FIG. 5 , the control signal may maintain the level of e1 in order to supply a current having a constant level of e5 to the load connected to the electric device 510 . Also, in order to estimate an internal parameter of the capacitor 511 connected to the electrical device 510, a perturbation signal having a magnitude of e2 may be injected into the control signal. At this time, when the magnitude of the load current increases from e5 to e7, the operating point of the control signal may increase from e1 to e3 so that the electric device 510 supplies the increased current. Accordingly, the voltage and current of each part of the electric device 510 may vary greatly. The perturbation signal is an interaction from the outside to the extent that the state of the system does not change significantly, and when the voltage and current of each part of the electrical device change significantly, that is, when the state of the system changes significantly, the perturbation signal e2 is meaningful as a perturbation signal It is impossible to estimate the transfer function using the perturbation signal e2 and the current e4 of the capacitor 511. An embodiment for solving this problem is shown in FIG. 6 .

6 is a diagram illustrating an example in which a load current is changed when a perturbation signal as a disturbance signal is injected into an electric device to estimate an internal parameter of a capacitor according to an embodiment.

Referring to FIG. 6, the electrical devices 610, 620, and 630 may be connected in parallel. That is, the input terminals of the first electric device 610, the second electric device 620, and the third electric device 630 are all connected to one, and the first electric device capacitor 611 and the second electric device capacitor 621 , The third electric device capacitor 631 is connected to the output terminals of the first electric device 610, the second electric device 620, and the third electric device 630, respectively, and the first electric device 610 After the output terminal of the second electric device 620 and the output terminal of the third electric device 630 are all connected to one another, they can be connected to a load. In one embodiment, for convenience, the electric device and the electric device capacitor are composed of three, but it is preferable to consider that it can be divided into n (n is 3 or more) electric devices and capacitors. The first electric device 610 is set as a diagnosis device and a perturbation signal having a magnitude of f1 is injected as a disturbance signal, and the second electric device 620 is set as a canceling device and has a magnitude of f3. A signal can be injected. The third electric device may be set as a general device. Settings of the diagnosis device, the canceling device, and the general device corresponding to each electric device may be changed. The first electric device 610, the second electric device 620, and the third electric device 630 properly distribute the load current having the magnitude of f7 and supply it to the load. At this time, when the magnitude of the load current increases to f8, only the control signal of the third electric device 630 set as a general device increases from f5 to f6, and the increased load current is supplied. Therefore, the voltage and current operating points of each part of the first electric device 610 set as a diagnosis device and the second electric device 620 set as an offset device are maintained, and the perturbation signal having the magnitude of f1 and the f3 A perturbation signal having a magnitude is also effective. Therefore, the internal parameter of the first electric device capacitor 611 set by the diagnostic device can be estimated using the perturbation signal having the magnitude of f1 and the current 612 of the first electric device capacitor having the magnitude of f2. The internal parameter of the capacitor 621 of the second electric device can be estimated using the perturbation signal having the magnitude of f3 and the current 622 of the capacitor 622 of the second electric device having the magnitude of f4.

7 is a diagram showing an example of estimating internal parameters of a capacitor by injecting a step function signal as a disturbance signal into an electric device in a previous study.

Referring to FIG. 7 , a control signal connected to the electric device 710 may maintain a level of g1 in order to supply a constant current having a level of g5 to a load connected to the electric device 710 . In order to estimate the internal parameters of the capacitor 711 connected to the electric device 710, when a step function signal having a magnitude of g2 is injected into the control signal, the current of the capacitor 711 is converted to the step function signal g2. As a result, it may increase momentarily to the size of g4 and then decrease. A transfer function can be obtained by measuring the step function signal g2 and the current of the capacitor 711, the internal parameter of the capacitor can be estimated using the transfer function, and the aging of the capacitor can be estimated using the estimated internal parameter. there is. However, due to the step function signal having a magnitude of g2 injected to estimate the internal parameter of the capacitor 711, the load current may increase to a magnitude of g6 without maintaining a constant level of g5. Therefore, since the load current is changed while estimating the internal parameters, this method is practically inapplicable. An embodiment for solving this problem is shown in FIG. 8 .

8 is a diagram illustrating an example of estimating an internal parameter of a capacitor by injecting a step function signal into an electric device as a disturbance signal according to an embodiment.

Referring to FIG. 8 , the electrical devices 810, 820, and 830 may be connected in parallel. That is, the input terminals of the first electric device 810, the second electric device 820, and the third electric device 830 are all connected to one, and the first electric device capacitor 811 and the second electric device capacitor 821 , The third electric device capacitor 831 is connected to the output terminals of the first electric device 810, the second electric device 820, and the third electric device 830, respectively, and the first electric device 810 After the output terminal of the second electric device 820 and the output terminal of the third electric device 830 are all connected to one another, they can be connected to a load. In one embodiment, for convenience, the electric device and the electric device capacitor are composed of three, but it is preferable to consider that it can be divided into n (n is 3 or more) electric devices and capacitors. When estimation of internal parameters of the capacitor starts, an electrical device connected to the capacitor whose internal parameters are to be measured may be set as a diagnostic device. In one embodiment, the first electric device 810 may be set as a diagnosis device, the second electric device 820 may be set as a canceling device, and the third electric device 830 may be set as a general device. Diagnosis device, offset device, and general device settings corresponding to each electric device can be changed. In the first electric device 810 set as a diagnostic device, a step function having a size of h1 is applied to the control signal of the first electric device 810 to estimate the internal parameter of the first electric device capacitor 811. ) signal, and a step function signal having a magnitude of h3 may be injected into the control signal of the second electric device 820 set as an offset device. The control signal of the third electric device 830 set as a general device may maintain the size of h5. The internal parameter of the first electric device capacitor 811 is estimated using the step function signal h1 signal of the control signal of the first electric device 810 set as a diagnosis device and the value h2 of the current 812 of the first electric device capacitor. and the internal parameter of the second electric device capacitor 821 using the step function signal h3 signal of the control signal of the second electric device 820 set as an offset device and the h4 value of the current 822 of the second electric device capacitor. can be estimated. Due to the second electrical device 820 set as a canceling device, the load current is maintained constant without distortion before and during the estimation of the internal parameters. Therefore, power loss due to vibration can be prevented and power quality can be maintained.

Terms such as "comprise", "comprise" or "having" described above mean that the corresponding component may be inherent unless otherwise stated, and therefore do not exclude other components. It should be construed that it may further include other components. All terms, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs, unless defined otherwise. Commonly used terms, such as terms defined in a dictionary, should be interpreted as consistent with the meaning in the context of the related art, and unless explicitly defined in the present invention, they are not interpreted in an ideal or excessively formal meaning.

The above description is merely an example of the technical idea of the present invention, and various modifications and variations can be made to those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but to explain, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed according to the claims below, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

Claims (15)

For three or more electrical devices constituting a parallel connection,
a measurement unit that obtains time-series data on currents of capacitors connected to output terminals of individual electrical devices constituting the parallel connection;
a control unit controlling individual electric devices constituting the parallel connection;
an estimator estimating an aging degree by estimating an internal parameter of the capacitor;
Parallel converter system implementation device for converter parameter estimation and continuous operation comprising a. According to claim 1,
The measuring unit,
a measurement circuit that amplifies or reduces the current of the capacitor and converts it into a voltage signal;
a filter for filtering a noise signal of a specific frequency band with respect to the signal output from the measuring circuit; and
an ADC (Analog-Digital-Converter) converting the signal output from the filter into a digital signal to obtain the time-series data;
Parallel converter system implementation device for converter parameter estimation and continuous operation comprising a. According to claim 1,
The control unit,
Control the electrical devices to supply the voltage and current required by the load connected to the output terminal of the electrical devices,
An apparatus for implementing a parallel converter system for estimating converter parameters and continuous operation for injecting a disturbance signal into individual electrical devices constituting the parallel connection to estimate internal parameters of the capacitor. According to claim 3,
The estimator,
When the estimation of the internal parameter of the capacitor starts, the transfer function of the capacitor is estimated through the disturbance signal output by the control unit and the time-series data corresponding to the same time point as the disturbance signal, and the internal parameter is estimated through the estimated transfer function. , Converter parameter estimation that estimates the degree of aging through the estimated internal parameters and a parallel converter system implementation device for continuous operation. According to claim 1,
The controller, the estimator, and the measurement unit implement a parallel converter system for estimating converter parameters and continuous operation in which operation clocks are synchronized. A method for estimating a capacitor internal parameter by a device,
For three or more electrical devices with inputs connected to each other and outputs connected to each other to form a parallel connection
a setting step of setting the individual electrical devices constituting the parallel connection as a diagnosis device, a canceling device, and a general device;
a control step of injecting a diagnosis signal as a disturbance signal into the diagnosis device, injecting a cancellation signal corresponding to the disturbance signal into the canceling device, and injecting a general signal into the general device;
a measurement step of acquiring first time-series data for the capacitor current of the diagnosis device and obtaining second time-series data for the capacitor current of the canceling device;
an estimation step of estimating the degree of aging of the capacitor of the diagnostic device by estimating an internal parameter of the capacitor of the diagnostic device, and estimating the degree of aging of the capacitor of the canceller by estimating an internal parameter of the capacitor of the canceller;
Capacitor internal parameter estimation method comprising a. According to claim 6,
A method for estimating a capacitor internal parameter is started by a timer or by an external signal. According to claim 6,
The setting step is
An electric device connected to a capacitor whose internal parameters are to be estimated is set as the diagnostic device,
Setting the canceling device that serves to prevent the load voltage or current from being distorted while estimating the internal parameter of the capacitor by compensating for the load voltage or current distortion due to the diagnostic signal injected into the diagnostic device;
setting the rest of the electric devices other than the diagnosis device and the canceling device as the general devices;
Capacitor internal parameter estimation method further comprising. According to claim 6,
The control step is
Injecting a perturbation signal or a step function signal as the diagnosis signal into the diagnosis device,
Generating the cancellation signal through calculation and injecting it into the cancellation device so that the cancellation device compensates for the distortion of the load voltage or current when the diagnosis signal is injected into the diagnosis device so that the load voltage or current can be maintained. ;
Capacitor internal parameter estimation method further comprising. According to claim 9,
The control step is
supplying voltage or current to the load by the electric device set as the general device when the voltage or current required by the load is changed while estimating the internal parameter of the capacitor;
Capacitor internal parameter estimation method further comprising. According to claim 6,
In the measuring step,
Measuring the capacitor current from the moment the diagnostic signal is injected into the diagnostic device until the capacitor current connected to the diagnostic device passes through a transient response and stabilizes in a steady state;
measuring the capacitor current from the moment the cancellation signal is injected into the cancellation device until the capacitor current connected to the cancellation device passes through a transient response and stabilizes in a steady state;
Capacitor internal parameter estimation method further comprising. According to claim 11,
In the measuring step,
acquiring the first time-series data and the second time-series data by amplifying or reducing the capacitor current and converting it into a voltage signal, filtering a noise signal of an unnecessary frequency band, and converting it into a digital signal;
Capacitor internal parameter estimation method further comprising. According to claim 11,
In the measuring step,
ADCs (Analog-Digital-Converters) for acquiring the first time-series data and the second time-series data
A method for estimating internal parameters of a capacitor comprising: According to claim 6,
The estimation step is
estimating a transfer function of the capacitor of the diagnostic device using the diagnostic signal and the first time-series data, estimating an internal parameter of the capacitor based on the transfer function, and estimating a degree of aging of the capacitor based on the internal parameter;
Estimating a transfer function of the cancellation device capacitor with the cancellation signal and the second time series data, estimating an internal parameter of a diagnostic device capacitor based on the transfer function, and estimating a degree of aging of the capacitor based on the internal parameter step;
Capacitor internal parameter estimation method further comprising. According to claim 14,
The estimation step is
Obtaining the diagnostic signal and the first time-series data at the same time to obtain a transfer function of the capacitor of the diagnostic device;
acquiring the cancellation signal and the second time-series data at the same point in time to obtain a transfer function of the cancellation device capacitor;
Capacitor internal parameter estimation method further comprising.

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