KR102638961B1 - Inverter apparatus capable of high speed operation mode switching and high speed start-up and control method thereof - Google Patents

Abstract

The present invention relates to an inverter device and control method capable of high-speed operation mode switching and high-speed start-up, which can reduce installation costs and improve management convenience by implementing the functions of an uninterruptible power supply device and an energy storage device simultaneously. This relates to an inverter device and control method that enables high-speed operation mode switching and high-speed start-up.

Description

Inverter device and control method capable of high-speed operation mode switching and high-speed start-up {INVERTER APPARATUS CAPABLE OF HIGH SPEED OPERATION MODE SWITCHING AND HIGH SPEED START-UP AND CONTROL METHOD THEREOF}

The present invention relates to an inverter device and control method capable of high-speed operation mode switching and high-speed start-up. More specifically, it is implemented to simultaneously perform the functions of an uninterruptible power supply device and an energy storage device, thereby reducing installation costs and improving management convenience. This relates to an inverter device and control method that enables improved high-speed operation mode switching and high-speed start-up.

An inverter device is a power conversion device that converts direct current (DC) power into alternating current (AC) power. It periodically cuts off and connects direct current power through a switching element, and adjusts the periodic cutting and connecting cycle to adjust the desired voltage and frequency. It is used to generate alternating current power and supply power to load devices.

Inverter devices are being used in a wide variety of fields due to the advancement of power conversion technology, and representative examples include uninterruptible power devices and energy storage devices.

An uninterruptible power supply is a device that stores power in a battery during normal times and converts the DC power of the battery into AC power when an abnormality occurs in the AC power such as a power outage, low voltage, overvoltage, low frequency, or overfrequency, and supplies uninterruptible power to load devices. am.

The inverter applied to the uninterruptible power supply device operates in voltage control mode and converts direct current power into stable alternating current power of constant voltage and constant frequency to supply power to load devices.

Energy storage devices have recently been attracting attention as an issue of reducing peak power and stabilizing renewable energy power. They are devices that store power in a battery at normal times and then convert the battery's DC power to AC power when necessary to supply power to load devices.

The inverter applied to the energy storage device operates in a current control mode. When charging, it converts AC power to DC power and stores power in the battery. When discharging, it converts DC power to AC power to supply power to the load device. supply.

However, in the past, uninterruptible power supplies and energy storage devices were installed and operated separately, so installation costs were high and management was difficult.

In addition, in the existing uninterruptible power supply system with priority supply of commercial power, in order to quickly transfer to the inverter power source and supply uninterruptible power to the load when a power failure occurs, the inverter's power circuit must be switched after waiting in a no-load operation state, so the inverter's power circuit must be switched on. There was a problem of no-load loss occurring.

Therefore, the present invention seeks to propose a method that can simultaneously perform the functions of an uninterruptible power supply device and an energy storage device.

In particular, the present invention isolates the system power from the load when an abnormality in the supply power is detected while performing the function of an energy storage device in a normal state, then quickly switches the currently operating current control mode to the power control mode, and reduces no-load loss. To minimize this, the inverter power circuit is left on standby in an off state and can be started at high speed when a power failure occurs.

Next, we will briefly describe the prior inventions existing in the technical field of the present invention, and then describe the technical details that the present invention seeks to achieve differently compared to the prior inventions.

Korean Patent Publication No. 10-2018-0078562 (2022.08.29.) provides an additional current control switch and an uninterruptible control switch in the uninterruptible power supply device, allowing it to be operated by a current-type control method during regular operation, and during uninterruptible operation. In the case of operation, it is operated by a voltage-type control method. In particular, the distortion is controlled to within 3% by the voltage-type control method, and at the same time, the voltage drop phenomenon is prevented to increase a series of performance efficiency. This is a prior invention regarding an uninterruptible power supply that also serves as a power regulator for energy storage devices with improved voltage efficiency.

However, the present invention converts the currently operating current control mode to the power control mode at high speed when a power abnormality is detected, and performs high-speed startup when a power abnormality occurs in the standby state to minimize no-load loss, and is a voltage-type control method. Compared to Korea Patent Publication No. 10-2018-0078562, which describes controlling distortion to within 3% and preventing voltage drop, there is a significant difference in composition.

The present invention was created to solve the above problems, and its purpose is to provide an inverter device and control method that can simultaneously perform the functions of an uninterruptible power supply device and an energy storage device.

In addition, the present invention is capable of disconnecting the system power from the load and switching the currently operating operation mode from the current control mode to the power control mode at high speed when an abnormality in the supply power is detected while performing the function of the energy storage device in normal times. Another purpose is to provide an inverter device and control method.

Another object of the present invention is to provide an inverter device and control method that can minimize no-load loss by keeping the inverter power circuit in an off state and then starting it at high speed when a power failure occurs.

However, the technical challenges that this embodiment aims to achieve are not limited to the technical challenges described above, and other technical challenges may exist.

An inverter device capable of high-speed operation mode switching and high-speed start-up according to an embodiment of the present invention includes a switch that connects or blocks system power to a load device; A bi-directional inverter that converts the system power supplied to the load device through the switch into direct current power and outputs it to a battery, or converts the direct current power stored in the battery into alternating current power and outputs it to the load device or system power; A DC-DC converter that steps down or boosts direct current power supplied from the bidirectional inverter or the battery and outputs it; A power abnormality detection unit that detects the presence or absence of an abnormality in the system power supply; and an inverter control unit that controls the bi-directional inverter to operate in any one of charging mode, discharging mode, standby mode, and uninterruptible power supply mode depending on the detected abnormality in the system power supply.

In addition, the DC-DC converter is used when the minimum operating voltage of the battery is lower than the minimum operating DC voltage of the bidirectional inverter, and charges the battery by stepping down the DC power output from the bidirectional inverter. The DC power of the battery is boosted and supplied to the bidirectional inverter, and is not used when the minimum operating voltage of the battery is equal to or higher than the minimum operable DC voltage of the bidirectional inverter.

In addition, when an abnormality occurs in the grid power, the inverter control unit controls the operation of the bidirectional inverter to quickly switch the current current control mode to the voltage control mode, or to quickly start the inverter from the off state to the voltage control mode. It is characterized in that it controls the operation of the bidirectional inverter.

In addition, the current control mode is a mode in which the charging power or discharging power of the battery is controlled to be equal to the power value commanded from the inverter control unit according to the charging mode or discharging mode operation, and the voltage control mode is a mode in which the uninterruptible power The mode is characterized in that the alternating current output voltage and frequency output from the bidirectional inverter are controlled to be constant according to the power supply mode operation.

In addition, in the charging mode, in a state where system power is supplied to the load device through the switch, the system power is converted into DC power through the bi-directional inverter, and the converted DC power is converted into DC power through the DC-DC converter. It is characterized in that it is a mode in which pressure is forced and stored in the battery.

In addition, in the discharge mode, the DC power of the battery is boosted through the DC-DC converter and supplied to the bi-directional inverter, the DC power is converted into AC power through the bi-directional inverter, and then the converted AC power is used. It is characterized in that the mode is supplied simultaneously with the system power or supplied independently depending on the discharge capacity and load capacity of the load-side device.

In addition, the standby mode is a mode in which there is no need to charge or discharge the battery, and the system power is supplied from the load device through the switch, and the two-way inverter is turned off to minimize loss of the inverter device. The DC-DC converter is placed on standby in an off state or in an operating state to maintain the DC link voltage above a certain value when the voltage of the battery does not meet a preset standard, and the off state is in the standby state. , The gate signal of the semiconductor device that performs power conversion, including the IGBT (Insulated Gate Bipolar Transistor), is maintained in an off state and does not perform power conversion operation.

In addition, in the uninterruptible power supply mode, when an abnormality in the grid power is detected through the power abnormality detection unit, the switch is turned off to cut off the grid power supplied to the load device, and the charging mode of the currently running bidirectional inverter is activated. Alternatively, the current control mode according to the discharge mode is quickly switched to the voltage control mode, or the bidirectional inverter in standby mode is started at high speed in the voltage control mode, and then the DC-DC converter boosts the DC-DC converter through the bidirectional inverter. This mode is characterized by converting power into alternating current power and supplying it to the load-side device, thereby receiving inverter power from the load-side device in an uninterrupted manner.

Additionally, the inverter control unit may include a switching unit that turns the switch on or off; an operation mode confirmation unit that checks the operation mode of the bidirectional converter currently in operation; A current control mode driver that generates a PWM control signal for driving the current control mode and outputs it to the bidirectional inverter if the currently operating mode is a charging mode or a discharging mode as a result of the confirmation; A voltage control mode driver that generates a PWM control signal for driving a voltage control mode and outputs it to the bidirectional inverter if the currently operating mode is an uninterruptible power supply mode or a standby mode as a result of the confirmation. And controlling the switch operation through the switching unit according to the presence or absence of an abnormality in the system power supply, checking the operation mode of the bidirectional converter, driving the current control mode according to the currently operating operation mode, high-speed switching to the voltage control mode, and high-speed starting of the voltage control mode. Characterized in that it includes a controller that controls.

In addition, the current control mode driver converts the three-phase AC input current measurement values (Ia/Ib/Ic) and AC input voltage measurement values (Va/Vb/Vc) of R, S, and T to the input current measurement value of the DQ0 axis ( Id/Iq/I0) and first and second ABC/DQ0 conversion units for converting the input voltage measurement value (Vq); A first PLL unit that determines the phase value (θ) of the rotating DQ0 axis using the R-phase AC input voltage measurement value (Va); A DC voltage PI control unit that outputs a command value (Iq*) of the alternating current active current by proportional integral control of the result of comparing the DC voltage command value (Vdc*) and the actual DC voltage measurement value (Vdc); DC voltage balance PI control unit that outputs the command value (I0*) of 0-phase alternating current so that the voltage difference (Vdc(+)-Vdc(-)) between the (+) and (-) terminals of the DC voltage measurement value is 0. ; The D-axis determines the D-axis control value by proportional integral control of the result of comparing the command value (Id*) of the AC reactive current and the input current measurement value (Id) converted to the DQ0 axis through the first ABC/DQ0 converter. Current PI control unit; Q determines the Q-axis control value by proportional integral control of the result of comparing the command value (Iq*) of the alternating current active current and the input current measurement value (Iq) converted to the DQ0 axis through the first ABC/DQ0 converter. Axial current PI control unit; The result of comparing the command value (I0*) of the 0-phase alternating current and the input current measurement value (I0) converted to the DQ0 axis through the first ABC/DQ0 converter is controlled by proportional integral control to obtain ( A 0-phase current PI control unit that determines a 0-phase current control value so that the voltage difference (Vdc(+)-Vdc(-)) between the +) terminal and the (-) terminal is 0; And outputting control signals (PWM-A/PWM-B/PWM-C) generated by converting the determined D-axis control value, Q-axis control value, and 0-phase current control value from the DQ0 axis to the ABC coordinate axis to the bidirectional inverter. It is characterized in that it includes a first DQ0/ABC conversion unit.

At this time, the DC voltage PI control unit is a proportional integral controller with an upper/lower limit variable structure, and refers to a preset charging/discharging amount calculation algorithm, takes into account the grid power, and determines that the AC side power of the bidirectional inverter is equal to the commanded charging/discharging power. After calculating the Q-axis current value, referring to the preset upper and lower limit value conversion algorithm, in the case of charging mode, the command value (Iq*) of the alternating current active current corresponds to the charging amount calculated through the charging and discharging amount calculation algorithm. The upper limit value is gradually changed to change to the Q-axis current value, and in the case of discharge mode, the command value (Iq*) of the AC effective current is the Q-axis current value corresponding to the discharge amount calculated through the charge/discharge amount calculation algorithm. It is characterized by gradually changing the lower limit so that it changes to .

In addition, the voltage control mode driver converts the three-phase AC input current measurement values (-Ia/-Ib/-Ic) of R, S, and T and the AC input voltage measurement values (Va/Vb/Vc) into the input current of the DQ0 axis. Third and fourth ABC/DQ0 conversion units for converting measured values (Id/Iq/I0) and input voltage measured values (Vd/Vq/V0); a second PLL unit that determines the phase value (θ) of the rotating DQ0 axis using the R-phase AC input voltage measurement value (Va); A D-axis voltage PI control unit that performs proportional integral control and outputs the result of comparing the command value 0 and the input voltage measurement value (Vd) converted to the DQ0 axis through the fourth ABC/DQ0 converter; Q-axis voltage PI control unit that performs proportional integral control and outputs the result of comparing the AC voltage value (Vq*) to be output, which is a command value, and the input voltage measurement value (Vq) converted to the DQ0 axis through the fourth ABC/DQ0 converter. ; A 0-phase voltage PI control unit that performs proportional integral control and outputs the result of comparing the command value 0 and the input voltage measurement value (V0) converted to the DQ0 axis through the fourth ABC/DQ0 conversion unit; A D-axis current P control unit that proportionally controls and outputs the result of comparing the output value of the D-axis voltage PI control unit and the input current measurement value (Id) converted to the DQ0 axis through the third ABC/DQ0 converter; A Q-axis current P control unit that proportionally controls and outputs the result of comparing the output value of the Q-axis voltage PI control unit and the input current measurement value (Iq) converted to the DQ0 axis through the third ABC/DQ0 converter; A 0-phase current P control unit that proportionally controls and outputs the result of comparing the output value of the 0-phase voltage PI control unit and the input current measurement value (I0) converted to the DQ0 axis through the third ABC/DQ0 converter; And control signals (PWM-A/PWM-B/PWM-C) generated by converting the output values of the D-axis current P control unit, Q-axis current P control unit, and 0-phase current P control unit from the DQ0 axis to the ABC coordinate axis are transmitted in the bidirectional direction. It is characterized in that it includes a second DQ0/ABC conversion unit that outputs to an inverter.

At this time, the Q-axis voltage PI control unit applies a value corresponding to an AC output voltage other than 0 as the initial value of the integral term, so that the output value starts from a value corresponding to an AC output voltage other than 0, and changes from standby mode to voltage control mode. It is characterized by high-speed startup or high-speed switching from current control mode to voltage control mode.

In addition, the second DQ0/ABC conversion unit converts the output values of the D-axis current P control unit, Q-axis current P control unit, and 0-phase current P control unit from the DQ0 axis to the ABC coordinate axis, and converts the instantaneous value of the load current and a constant The control signal (PWM-A/PWM-B/PWM-C) reflected by adding the value multiplied by the coefficient value is output to the bidirectional inverter, thereby improving transient characteristics due to rapid load changes.

In addition, the method of controlling an inverter device capable of high-speed operation mode switching and high-speed startup according to an embodiment of the present invention detects whether an abnormality has occurred in the system power supplied to the load device in an inverter device capable of high-speed operation mode switching and high-speed startup. judging step; If an abnormality occurs in the system power as a result of the above determination, it is checked whether it is in voltage control mode. If it is in voltage control mode as a result of the above determination, it is started in uninterruptible power supply mode. If it is not in voltage control mode as a result of the above confirmation, it is started in voltage control mode. Converting and then starting into the uninterruptible power supply mode; If there is no problem with the system power as a result of the determination, determining whether it is in a charging or discharging command state; As a result of the above determination, if it is in the charging or discharging command state, it is checked whether it is in the current control mode. If it is in the current control mode as a result of the above determination, it is started in the charging mode or discharging mode. If it is not in the current control mode as a result of the above confirmation, it is switched to the current control mode. and then starting into charge mode or discharge mode; And if it is not in the charging or discharging command state as a result of the determination, starting in standby mode; high-speed starting from standby mode to voltage control mode or from current control mode to voltage control mode depending on an abnormality in the system power supply. It is characterized by supporting high-speed switching.

As described above, according to the inverter device and control method capable of high-speed operation mode switching and high-speed start-up of the present invention, when a power abnormality is detected while performing the energy storage function, the system power and load are separated and then the currently operating operation is performed. By changing the mode from current control mode to power control mode at high speed and starting at high speed when a power failure occurs in standby mode to minimize no-load loss, installation costs can be reduced and inverter device management can be conveniently performed. There is a possible effect.

However, the effects of the present invention are not limited to the effects described above, and effects not mentioned can be clearly understood by those skilled in the art from this specification and the attached drawings.

Figure 1 is a diagram schematically showing the overall configuration of an inverter device capable of high-speed operation mode switching and high-speed start-up according to an embodiment of the present invention.
Figure 2 is a block diagram showing the configuration of the inverter control unit of the inverter device according to an embodiment of the present invention in more detail.
Figure 3 is a diagram for explaining charging mode driving of an inverter device according to an embodiment of the present invention.
Figure 4 is a diagram for explaining discharge mode driving of an inverter device according to an embodiment of the present invention.
Figure 5 is a diagram for explaining standby mode operation of an inverter device according to an embodiment of the present invention.
Figure 6 is a diagram for explaining the uninterruptible power supply mode operation of the inverter device according to an embodiment of the present invention.
FIG. 7 is a diagram showing the configuration of the current control mode driver of the inverter control unit of FIG. 2 in more detail.
FIG. 8 is a diagram showing the configuration of the voltage control mode driver of the inverter control unit of FIG. 2 in more detail.
Figure 9 is a flowchart showing in more detail the operation mode switching process of the inverter device according to an embodiment of the present invention.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. However, the spirit of the present invention is not limited to the presented embodiments, and those skilled in the art who understand the spirit of the present invention may add, change, or delete other components within the scope of the same spirit, or create other degenerative inventions or this invention. Other embodiments that are included within the scope of the invention can be easily proposed, but this will also be said to be included within the scope of the invention of the present application.

In addition, components having the same function within the scope of the same idea shown in the drawings of each embodiment will be described using the same reference numerals.

Figure 1 is a diagram schematically showing the entire configuration including an inverter device capable of high-speed operation mode switching and high-speed start-up according to an embodiment of the present invention.

As shown in FIG. 1, the inverter device 100 (hereinafter referred to as the inverter device) capable of high-speed operation mode switching and high-speed startup of the present invention includes a switch 110, a power abnormality detection unit 120, an inverter control unit 130, It is composed of a DC-DC converter control unit 140, a DC-DC converter 150, a bidirectional inverter 160, and a battery 170.

The switch 110 performs the function of connecting or blocking system power to load devices.

At this time, the switch 110 may use a static switch, which is an electric switch without mechanical contact that can operate at high speed and without power failure.

The power abnormality detection unit 120 measures the voltage and frequency of the system power supply, checks whether an abnormality such as low voltage, overvoltage, low frequency, or overfrequency occurs, and provides the confirmed result to the inverter control unit 130. do.

The inverter control unit 130 operates the bidirectional inverter 160 in any one of charging mode, discharging mode, standby mode, and uninterruptible power supply mode depending on whether there is an abnormality in the system power input from the power abnormality detection unit 120. Control it to run.

As an example, when an abnormality occurs in the system power as a result of detection by the power abnormality detection unit 120, the inverter control unit 130 turns off the switch 110 and changes the currently operating current control mode to the voltage control mode. The operation of the bidirectional inverter 160 is controlled to achieve high-speed switching.

In addition, the inverter control unit 130 operates at high speed in voltage control mode when an abnormality occurs in the system power as a result of detection by the power abnormality detection unit 120 and when the power circuit of the bidirectional inverter 160 is in an off state. The operation of the bidirectional inverter 160 is controlled so that the uninterruptible power supply function is immediately performed.

At this time, the current control mode is controlled so that when the inverter device 100 is driven in the charging mode or discharging mode, the charging power or discharging power of the battery 170 is equal to the power value commanded from the inverter control unit 130. It's a mode.

Additionally, the voltage control mode is a mode in which the alternating current output voltage and frequency output from the bidirectional inverter 160 are controlled to be constant when the inverter device 100 is driven in the uninterruptible power supply mode.

The DC-DC converter control unit 140 controls step-down or step-up operation of the DC-DC converter 150 based on the control of the inverter control unit 130.

The DC-DC converter 150 steps down or boosts the direct current power supplied from the bidirectional inverter 160 or the battery 170 and outputs it.

That is, the DC-DC converter 150 is used when the minimum operating voltage of the battery 170 is lower than the minimum operating DC voltage of the bi-directional inverter 160, and the DC-DC converter control unit 140 According to control, the DC power supplied from the bidirectional inverter 160 is stepped down to charge the battery 170.

In addition, the DC-DC converter 150 boosts the DC power supplied from the battery 170 under the control of the DC-DC converter control unit 140 and outputs it to the bidirectional inverter 160.

Meanwhile, the DC-DC converter 150 is not used when the minimum operating voltage of the battery 170 is equal to or higher than the minimum operating DC voltage of the bidirectional inverter 160.

The bidirectional inverter 160 converts system power (i.e., AC power) supplied to the load-side device through the switch 110 into DC power and outputs it to the DC-DC converter 150 to charge the battery 170. Let them do it.

In addition, the bidirectional inverter 160 receives the direct current power stored in the battery 170 through the DC-DC converter 150, converts the direct current power into alternating current power, and outputs it to the load device or system power.

The battery 170 charges the power supplied through the bidirectional inverter 160 and the DC-DC converter 150 when grid power is normally supplied to the inverter device 100, and when an abnormality occurs in the grid power The charged power is supplied to the load device through the DC-DC converter 150 and the bi-directional inverter 160.

Figure 2 is a block diagram showing the configuration of the inverter control unit of the inverter device according to an embodiment of the present invention in more detail.

As shown in FIG. 2, the inverter control unit 130 includes a switching unit 131, an operation mode confirmation unit 132, a current control mode driver 133, a voltage control mode driver 134, a controller 135, etc. It is composed including.

The switching unit 131 turns the switch 110 on or off under the control of the controller 135.

The operation mode confirmation unit 132 checks the currently operating operation mode and provides information about the confirmed operation mode to the controller 135.

As a result of checking through the operation mode confirmation unit 132, the current control mode driver 133 operates a PWM for current control mode driving under the control of the controller 135 if the currently operating mode is a charging mode or a discharging mode. A control signal is generated and output to the bidirectional inverter 160.

As a result of checking through the operation mode confirmation unit 132, the voltage control mode driver 134 operates the voltage control mode under the control of the controller 135 if the currently operating mode is the uninterruptible power supply mode or standby mode. A PWM control signal is generated and output to the bidirectional inverter 160.

Here, the specific driving of the current control mode driver 133 and the voltage control mode driver 134 is described in more detail in FIGS. 7 and 8.

The controller 135 controls switch driving through the switching unit 131 according to the presence or absence of an abnormality in the system power source confirmed through the detection result by the power abnormality detection unit 120.

In addition, the controller 135 checks the operation mode of the bidirectional converter 160 through the operation mode confirmation unit 132, and operates the current control mode driver 133 and the voltage control mode driver according to the currently operating operation mode ( 134) controls current control mode operation, voltage control mode high-speed switching, and voltage control mode high-speed startup.

Next, charging mode, discharging mode, standby mode, and uninterruptible power supply mode will be described in detail with reference to FIGS. 3 to 6.

3 to 6 are diagrams for explaining the operation of the inverter device in charging mode, discharging mode, standby mode, and uninterruptible power supply mode, respectively, according to an embodiment of the present invention.

As shown in FIG. 3, the charging mode converts the system power to direct current power through the bidirectional inverter 160, and then steps down the converted direct current power through the DC-DC converter 150 to supply the battery to the battery. This mode saves to (170).

That is, the charging mode is a mode in which the battery 170 is charged using the grid power while the grid power is supplied to the load device through the switch 110.

In addition, as shown in FIG. 4, in the discharge mode, the DC power charged in the battery 170 is boosted through the DC-DC converter 150 and supplied to the bidirectional inverter 160, and the bidirectional inverter ( 160), this is a mode in which DC power is converted into AC power and supplied to the load device.

At this time, depending on the discharge capacity and load capacity of the load-side device, the AC power and system power converted by the bi-directional inverter 160 are simultaneously supplied to the load-side device as shown in (a) of FIG. 4, or (b) of FIG. 4 ) can be supplied alone as in.

Additionally, as shown in FIG. 5, the standby mode is a mode in which there is no need to charge or discharge the battery 170 and the system power is supplied from the load device through the switch 110.

At this time, in order to minimize the loss of the inverter device 100, the power circuit of the bidirectional inverter 160 is placed in an off state and the DC-DC converter 150 is placed in an off state. If the voltage does not meet the preset standard, the DC link voltage is put on standby in an operating state to maintain it above a certain value.

Here, the off state of the power circuit refers to a state in which the gate signal of a semiconductor device that performs power conversion, including an IGBT (Insulated Gate Bipolar Transistor), is maintained in an off state and does not perform a power conversion operation.

In addition, as shown in FIG. 6, in the uninterruptible power supply mode, when an abnormality in the system power is detected through the power abnormality detection unit 120, the switch 110 is turned off to turn off the system power supplied to the load device. Block.

Subsequently, the current control mode according to the charging mode or discharging mode of the currently operating bidirectional inverter 160 is quickly switched to voltage control mode, or the bidirectional inverter 160 in standby mode is rapidly started in voltage control mode.

Then, the DC power of the battery 170 boosted by the DC-DC converter 150 is converted into AC power through the bi-directional inverter 160, and then supplied to the load device, which inverts the load device without interruption. It receives power so that it can operate without power outage.

Next, with reference to FIGS. 7 and 8, the operation of the current control mode and voltage control mode applied to the inverter device 100 of the present invention will be described in detail.

FIG. 7 is a diagram showing the configuration of the current control mode driver 133 of the inverter control unit 130 of FIG. 2 in more detail.

As shown in FIG. 7, the current control mode driver 133 is configured to ensure that the charging power or discharging power of the battery 170 is equal to the commanded power value when the inverter device 100 is in charging mode or discharging mode. For controlling, a first ABC/DQ0 conversion unit, a second ABC/DQ0 conversion unit, a first PLL unit, DC voltage PI control unit, DC voltage balance PI control unit, D-axis current PI control unit, Q-axis current PI control unit, 0 It is composed of a phase current PI control unit, a first DQ0/ABC conversion unit, etc.

The first ABC/DQ0 conversion unit converts the three-phase AC input current measurement values (Ia/Ib/Ic) of R, S, and T into the input current measurement values (Id/Iq/I0) of the DQ0 axis.

The second ABC/DQ0 conversion unit converts the three-phase AC input voltage measurement values (Va/Vb/Vc) of R, S, and T into the input voltage measurement values (Vq) of the DQ0 axis.

The first PLL unit determines the phase value (θ) of the rotating DQ0 axis using the R-phase AC input voltage measurement value (Va).

The DC voltage PI controller is a proportional integral controller with an upper/lower limit variable structure and is used to control the DC voltage of the external loop. In other words, the result of comparing the DC voltage command value (Vdc*) and the actual DC voltage measurement value (Vdc) is controlled by proportional integral control to output the command value (Iq*) of the alternating current active current.

To be more specific, the DC voltage PI control unit generates an output value by comparing the DC voltage command value (Vdc*) and the actual DC voltage measurement value (Vdc). In this case, the output value refers to the alternating current active current, and the Q axis It becomes the command value of the current PI control unit.

Here, the DC voltage PI control unit refers to a preset charging/discharging amount calculation algorithm and an upper/lower limit switching algorithm when generating an output value that is the AC effective current.

As an example, the charging/discharging amount calculation algorithm considers the grid power and calculates a Q-axis current value at which the alternating current power of the bidirectional inverter 160 is equal to the commanded charging/discharging power.

Subsequently, the upper and lower limit value switching algorithm gradually changes the upper limit value so that in the charging mode, the command value (Iq*) of the alternating current effective current is changed to the Q-axis current value corresponding to the charging amount calculated through the charging and discharging amount calculation algorithm. .

In addition, the upper and lower limit value switching algorithm gradually changes the lower limit value so that when in discharge mode, the command value (Iq*) of the alternating current effective current is changed to the Q-axis current value corresponding to the discharge amount calculated through the charge and discharge amount calculation algorithm. do.

The DC voltage balance PI control unit is an additional component when using a 3-phase 4-wire power supply, and is configured to control the balance between the (+) and (-) terminals of the external loop, and the 0-phase component of the 3-phase alternating current and The result of comparing the voltage difference (Vdc(+)-Vdc(-)) between the (+) and (-) terminals of the DC voltage measurement value is proportionally integrated to output the command value (I0*) of the 0-phase alternating current.

In other words, the command value (I0*) of the 0-phase alternating current is output so that the voltage difference (Vdc(+)-Vdc(-)) between the (+) and (-) terminals of the DC voltage measurement value is 0. An output value is generated so that the voltage difference between the (+) terminal and the (-) terminal is 0, and the output value becomes the command value of the 0-phase current PI controller.

The D-axis current PI control unit is a component for controlling the alternating current at the input terminal of the inner loop together with the Q-axis current PI control unit, and the DQ0 axis through the command value (Id*) of the alternating reactive current and the first ABC/DQ0 converter. The D-axis control value is determined by proportional integral control of the result of comparing the converted input current measurement value (Id).

At this time, the command value (Id*), which means the AC reactive current input to the D-axis current PI control unit, is normally applied as 0, and can be applied as a value corresponding to the required AC reactive current when necessary.

The Q-axis current PI control unit performs proportional integral control on the result of comparing the command value (Iq*) of the alternating current active current and the input current measurement value (Iq) converted to the DQ0 axis through the first ABC/DQ0 converter to control Q Determine the axis control value.

The 0-phase current PI control unit is a component for controlling the 0-phase current of the inner loop, and measures the command value (I0*) of the 0-phase alternating current and the input current converted to the DQ0 axis through the first ABC/DQ0 conversion unit. By proportional integral control of the result compared with the value (I0), the 0-phase current control value is set so that the voltage difference (Vdc(+)-Vdc(-)) between the (+) and (-) terminals of the DC voltage measurement value is 0. decide.

That is, the 0-phase current is controlled according to the output value of the DC voltage balance PI controller so that the voltage difference between the DC (+) terminal and (-) terminal is 0.

The first DQ0/ABC conversion unit converts the D-axis control value, Q-axis control value, and 0-phase current control value determined by the D-axis current PI control unit, Q-axis current PI control unit, and 0-phase current PI control unit, respectively, from the DQ0 axis to the ABC coordinate axis. The control signals (PWM-A/PWM-B/PWM-C) generated by converting are output to the bidirectional inverter 160.

FIG. 8 is a diagram showing the configuration of the voltage control mode driver 134 of the inverter control unit 130 of FIG. 2 in more detail.

As shown in FIG. 8, the voltage control mode driver 134 is for controlling the alternating current output voltage and frequency to be constant when the inverter device 100 is in the uninterruptible power supply mode, and the third ABC/DQ0 converter , fourth ABC/DQ0 conversion unit, second PLL unit, D-axis voltage PI control unit, Q-axis voltage PI control unit, 0-phase voltage PI control unit, D-axis current P control unit, Q-axis current P control unit, 0-phase current P control unit, It is configured to include a second DQ0/ABC conversion unit, etc. And the three-phase AC voltage value is converted from the ABC coordinate axis to the DQ0 coordinate axis and control is performed on the DQ0 axis.

The third ABC/DQ0 conversion unit converts the three-phase AC input current measurement values (-Ia/-Ib/-Ic) of R, S, and T into input current measurement values (Id/Iq/I0) of the DQ0 axis.

The fourth ABC/DQ0 conversion unit converts the three-phase AC input voltage measurement values (Va/Vb/Vc) of R, S, and T into the input voltage measurement values (Vd/Vq/V0) of the DQ0 axis.

The second PLL unit determines the phase value (θ) of the rotating DQ0 axis using the R-phase AC input voltage measurement value (Va).

The D-axis voltage PI control unit is a component for controlling the alternating current voltage of the external loop together with the Q-axis voltage PI control unit and the 0-phase voltage PI control unit, and is converted to the DQ0 axis through the command value 0 and the fourth ABC/DQ0 conversion unit. The result of comparing the input voltage measurement value (Vd) is output through proportional integral control.

In other words, an output value is generated by comparing the command value with the measured value. This is the same for the Q-axis voltage PI control unit and the 0-phase voltage PI control unit, and the output value of the D-axis/Q-axis/0-phase voltage PI control unit becomes the command value of the D-axis/Q-axis/0-phase current P controller, respectively.

The Q-axis voltage PI control unit performs proportional integral control on the result of comparing the AC voltage value (Vq*) to be output, which is a command value, with the input voltage measurement value (Vq) converted to the DQ0 axis through the fourth ABC/DQ0 converter. Print out.

At this time, the Q-axis voltage PI control unit may apply a value corresponding to the AC output voltage rather than 0 as the initial value of the integral term.

Here, the value corresponding to the AC output voltage is affected by the DC link voltage, the voltage drop of the inverter circuit, the controller design value, etc., and can be selected in the range of 2000 to 4000.

Accordingly, the output value of the Q-axis voltage PI control unit starts from a value corresponding to the AC output voltage rather than 0, making it possible to quickly start from standby mode to voltage control mode or quickly switch from current control mode to voltage control mode.

The 0-phase voltage PI control unit performs proportional integral control and outputs the result of comparing the command value 0 and the input voltage measurement value (V0) converted to the DQ0 axis through the fourth ABC/DQ0 converter.

The D-axis current P control unit is a component for controlling the alternating current of the inner loop together with the Q-axis current P control unit and the 0-phase current P control unit, and the output value of the D-axis voltage PI control unit and the third ABC/DQ0 converter The result of comparing the input current measurement value (Id) converted to the DQ0 axis is output under proportional control.

The Q-axis current P control unit proportionally controls and outputs the result of comparing the output value of the Q-axis voltage PI control unit and the input current measurement value (Iq) converted to the DQ0 axis through the third ABC/DQ0 converter.

The 0-phase current P control unit proportionally controls and outputs the result of comparing the output value of the 0-phase voltage PI control unit and the input current measurement value (I0) converted to the DQ0 axis through the third ABC/DQ0 converter.

The second DQ0/ABC conversion unit converts the output values of the D-axis current P control unit, Q-axis current P control unit, and 0-phase current P control unit from the DQ0 axis to the ABC coordinate axis to generate control signals (PWM-A/PWM-B/ PWM-C) is output to the bidirectional inverter (160).

In other words, the output value of the D-axis/Q-axis/0-phase current P controller is converted from the DQ0 coordinate axis to the ABC coordinate axis to generate a PWM signal.

Here, the voltage control mode driver 134 converts the output values of the D-axis current P control unit, Q-axis current P control unit, and 0-phase current P control unit to DQ0 in order to improve transient characteristics due to rapid load changes according to the voltage control mode. To output a control signal (PWM-A/PWM-B/PWM-C) reflected by adding the value converted from the axis to the ABC coordinate axis by multiplying the instantaneous value of the load current and a certain coefficient value to the bidirectional inverter 160. do.

Here, the coefficient value multiplied by the instantaneous value of the load current is affected by the voltage drop of the inverter circuit, the controller design value, etc., and can be selected in the range of 1 to 2.

Next, an embodiment of the inverter device control method configured as described above capable of high-speed operation mode switching and high-speed start-up according to the present invention will be described in detail with reference to FIG. 9. At this time, the order of each step according to the method of the present invention may be changed depending on the usage environment or a person skilled in the art.

Figure 9 is a flowchart showing in more detail the operation mode switching process of the inverter device according to an embodiment of the present invention.

As shown in FIG. 9, the inverter device 100 determines whether an abnormality has occurred in the system power supplied to the load device (S100).

If an abnormality occurs in the system power as determined through step S100, the inverter device 100 determines whether it is currently operating in the voltage control mode (S200).

If the determination in step S200 is in the voltage control mode, the inverter device 100 starts in the uninterruptible power supply mode driven in the voltage control mode and supplies the power charged in the battery 170 to the load device (S300) ).

However, if it is not in the voltage control mode as determined in step S200, the inverter device 100 switches to the voltage control mode (S400) and then starts in the uninterruptible power supply mode in step S300.

In addition, if there is no problem with the system power as determined through step S100, the inverter device 100 determines whether it is in a charging or discharging command state (S500).

If the charge or discharge command state is determined as a result of step S500, the inverter device 100 determines whether it is currently operating in the current control mode (S600).

If the inverter device 100 is in the current control mode as determined through step S600, the inverter device 100 is driven in a charging mode or a discharging mode driven in the current control mode to charge the system power to the battery 170, or the battery 170 ) to supply the power charged to the load device (S700).

However, if it is not in the current control mode as determined in step S600, the inverter device 100 switches to the current control mode (S800) and then starts in the charging mode or discharging mode in step S700.

In addition, if it is determined in step S500 that the charge or discharge command is not in the state, the inverter device 100 starts in standby mode with the inverter power circuit turned off (S900).

In other words, the inverter device 100 supports high-speed startup from standby mode to voltage control mode or high-speed switching from current control mode to voltage control mode depending on an abnormality in the system power.

In this way, in the present invention, when a power abnormality is detected while performing the energy storage device function, the system power source and the load are separated, and then the currently operating operation mode is switched from the current control mode to the power control mode at high speed, and the power supply is switched in the standby state. When an abnormality occurs, the no-load loss can be minimized by starting at high speed, which not only reduces installation costs but also allows convenient management of the inverter device.

In the attached drawings, in order to more clearly express the technical idea of the present invention, components that are unrelated or less relevant to the technical idea of the present invention are briefly expressed or omitted.

In the above, the configuration and features of the present invention have been described based on the embodiments according to the present invention, but the present invention is not limited thereto, and various changes or modifications may be made within the spirit and scope of the present invention. It is obvious to those skilled in the art, and therefore, it is stated that such changes or modifications fall within the scope of the appended patent claims.

100: Inverter device capable of high-speed operation mode switching and high-speed start-up
110: switch
120: Power failure detection unit
130: Inverter control unit
131: switching unit
132: Operation mode confirmation unit
133: Current control mode driver
134 ; Voltage control mode driver
135: controller
140: DC-DC converter control unit
150: DC-DC converter
160: Two-way inverter
170: battery

Claims (15)

A switch that connects or disconnects grid power to load devices;
A bi-directional inverter that converts the system power supplied to the load device through the switch into direct current power and outputs it to a battery, or converts the direct current power stored in the battery into alternating current power and outputs it to the load device or system power;
A DC-DC converter that steps down or boosts direct current power supplied from the bidirectional inverter or the battery and outputs it;
A power abnormality detection unit that detects the presence or absence of an abnormality in the system power supply; and
It includes an inverter control unit that controls the bidirectional inverter to operate in any one of charging mode, discharging mode, standby mode, and uninterruptible power supply mode according to the detected abnormality in the system power supply,
In the charging mode, in a state where system power is supplied to the load device through the switch, the system power is converted to DC power through the bi-directional inverter, and the converted DC power is stepped down through the DC-DC converter. This is a mode for storing in the battery,
In the discharge mode, the DC power of the battery is boosted through the DC-DC converter and supplied to the bidirectional inverter, the DC power is converted into AC power through the bidirectional inverter, and then the converted AC power is applied to the load. As a mode of supplying to devices, the converted AC power is supplied simultaneously with the system power according to the discharge capacity and load capacity of the load-side device,
In the standby mode, there is no need to charge or discharge the battery, and in a state where the system power is supplied through the switch from the load side device, the bidirectional inverter is turned off to standby to minimize no-load loss, and the The DC-DC converter is in an off state or in an operating state to maintain the DC link voltage above a certain value when the battery voltage does not meet a preset standard, and the bidirectional inverter is in the off state. is a state in which the gate signal of a semiconductor device that performs power conversion, including an IGBT (Insulated Gate Bipolar Transistor), is maintained in an off state and no power conversion operation is performed,
In the uninterruptible power supply mode, when an abnormality in the system power is detected through the power abnormality detection unit, the switch is turned off to cut off the system power supplied to the load device, and the system power supply to the load device is switched off according to the charging mode or discharging mode of the bidirectional inverter. Switch the current control mode to voltage control mode, or start the bidirectional inverter in standby mode in voltage control mode, and then convert the DC power of the battery boosted by the DC-DC converter into AC power through the bidirectional inverter. This is a mode in which inverter power is supplied uninterruptedly from the load-side device by supplying it to the load-side device,
The inverter control unit controls the operation of the bidirectional inverter to switch to voltage control mode when an abnormality occurs in the grid power while driving in the current control mode, and when an abnormality occurs in the grid power in the standby mode, Controlling the operation of the bidirectional inverter to start the bidirectional inverter in an off state in voltage control mode to minimize no-load loss,
The current control mode is a mode in which the charging current or discharging current of the battery is controlled to be equal to the current value commanded from the inverter control unit when driving in the charging mode or discharging mode,
The voltage control mode is a mode in which the alternating current output voltage and frequency output from the bidirectional inverter are controlled to be constant when operating in the uninterruptible power supply mode.
In claim 1,
The DC-DC converter is,
It is used when the minimum operating voltage of the battery is lower than the minimum operating DC voltage of the bidirectional inverter, to charge the battery by stepping down the DC power output from the bidirectional inverter, or to charge the battery by boosting the DC power of the battery. Supply to the inverter,
An inverter device characterized in that it is not used when the minimum operating voltage of the battery is equal to or higher than the minimum operable direct current voltage of the bidirectional inverter.
delete delete delete delete delete delete In claim 1,
The inverter control unit,
a switching unit that turns the switch on or off;
An operation mode confirmation unit that checks the operation mode of the bidirectional inverter currently in operation;
A current control mode driver that generates a PWM control signal for driving the current control mode and outputs it to the bidirectional inverter if the currently operating mode is a charging mode or a discharging mode as a result of the confirmation;
A voltage control mode driver that generates a PWM control signal for driving a voltage control mode and outputs it to the bidirectional inverter if the currently operating mode is an uninterruptible power supply mode or a standby mode as a result of the confirmation. and
Controls switch operation through the switching unit according to the presence or absence of an abnormality in the system power supply, checks the operation mode of the bidirectional inverter, controls current control mode operation according to the currently operating operation mode, voltage control mode switching, and voltage control mode start. An inverter device comprising a controller.
In claim 9,
The current control mode driver,
The three-phase AC input current measurements (Ia/Ib/Ic) and AC input voltage measurements (Va/Vb/Vc) of R, S, and T are converted to the input current measurements (Id/Iq/I0) and input voltage of the DQ0 axis. First and second ABC/DQ0 conversion units for converting to measured value (Vq);
A first PLL unit that determines the phase value (θ) of the rotating DQ0 axis using the R-phase AC input voltage measurement value (Va);
A DC voltage PI control unit that outputs a command value (Iq*) of the alternating current active current by proportional integral control of the result of comparing the DC voltage command value (Vdc*) and the actual DC voltage measurement value (Vdc);
DC voltage balance PI control unit that outputs the command value (I0*) of 0-phase alternating current so that the voltage difference (Vdc(+)-Vdc(-)) between the (+) and (-) terminals of the DC voltage measurement value is 0. ;
The D-axis determines the D-axis control value by proportional integral control of the result of comparing the command value (Id*) of the AC reactive current and the input current measurement value (Id) converted to the DQ0 axis through the first ABC/DQ0 converter. Current PI control unit;
Q determines the Q-axis control value by proportional integral control of the result of comparing the command value (Iq*) of the alternating current active current and the input current measurement value (Iq) converted to the DQ0 axis through the first ABC/DQ0 converter. Axial current PI control unit;
The result of comparing the command value (I0*) of the 0-phase alternating current and the input current measurement value (I0) converted to the DQ0 axis through the first ABC/DQ0 converter is controlled by proportional integral control to obtain ( A 0-phase current PI control unit that determines a 0-phase current control value so that the voltage difference (Vdc(+)-Vdc(-)) between the +) terminal and the (-) terminal is 0; and
The control signals (PWM-A/PWM-B/PWM-C) generated by converting the determined D-axis control value, Q-axis control value, and 0-phase current control value from the DQ0 axis to the ABC coordinate axis are output to the bidirectional inverter. An inverter device comprising a first DQ0/ABC conversion unit.
In claim 10,
The DC voltage PI control unit,
A proportional integral controller with a variable upper/lower limit structure,
With reference to the preset charge/discharge amount calculation algorithm, calculate the Q-axis current value at which the alternating current power of the bidirectional inverter is equal to the commanded charge/discharge power, taking into account the grid power,
Referring to the preset upper and lower limit value switching algorithm, in the case of charging mode, the upper limit value is gradually changed so that the command value (Iq*) of the AC active current is changed to the Q-axis current value corresponding to the charging amount calculated through the charging and discharging amount calculation algorithm. In the case of discharge mode, the lower limit value is gradually changed so that the command value (Iq*) of the alternating current active current is changed to the Q-axis current value corresponding to the discharge amount calculated through the charge/discharge amount calculation algorithm. inverter device.
In claim 9,
The voltage control mode driver,
Three-phase AC input current measurements (-Ia/-Ib/-Ic) and AC input voltage measurements (Va/Vb/Vc) of R, S, and T are converted to input current measurements (Id/Iq/I0) on the DQ0 axis. and third and fourth ABC/DQ0 conversion units for converting input voltage measurements (Vd/Vq/V0);
a second PLL unit that determines the phase value (θ) of the rotating DQ0 axis using the R-phase AC input voltage measurement value (Va);
A D-axis voltage PI control unit that performs proportional integral control and outputs the result of comparing the command value 0 and the input voltage measurement value (Vd) converted to the DQ0 axis through the fourth ABC/DQ0 converter;
Q-axis voltage PI control unit that performs proportional integral control and outputs the result of comparing the AC voltage value (Vq*) to be output, which is a command value, and the input voltage measurement value (Vq) converted to the DQ0 axis through the fourth ABC/DQ0 converter. ;
A 0-phase voltage PI control unit that performs proportional integral control and outputs the result of comparing the command value 0 and the input voltage measurement value (V0) converted to the DQ0 axis through the fourth ABC/DQ0 conversion unit;
A D-axis current P control unit that proportionally controls and outputs the result of comparing the output value of the D-axis voltage PI control unit and the input current measurement value (Id) converted to the DQ0 axis through the third ABC/DQ0 converter;
A Q-axis current P control unit that proportionally controls and outputs the result of comparing the output value of the Q-axis voltage PI control unit and the input current measurement value (Iq) converted to the DQ0 axis through the third ABC/DQ0 converter;
A 0-phase current P control unit that proportionally controls and outputs the result of comparing the output value of the 0-phase voltage PI control unit and the input current measurement value (I0) converted to the DQ0 axis through the third ABC/DQ0 converter; and
The control signals (PWM-A/PWM-B/PWM-C) generated by converting the output values of the D-axis current P control unit, Q-axis current P control unit, and 0-phase current P control unit from the DQ0 axis to the ABC coordinate axis are sent to the bidirectional inverter. An inverter device comprising a second DQ0/ABC converter that outputs .
In claim 12,
The Q-axis voltage PI control unit,
By applying the value corresponding to the AC output voltage other than 0 as the initial value of the integral term, the output value starts from the value corresponding to the AC output voltage other than 0, and can be started at high speed from standby mode to voltage control mode or from voltage control mode to current control mode. An inverter device that allows high-speed switching to control mode.
In claim 12,
The second DQ0/ABC conversion unit,
A control signal ( An inverter device characterized by improving transient characteristics due to rapid load changes by outputting (PWM-A/PWM-B/PWM-C) to the bidirectional inverter.
As performed in the inverter device described in claim 1,
Determining whether an abnormality has occurred in the system power supplied to the load-side device;
If an abnormality occurs in the system power as a result of the above determination, it is checked whether it is in voltage control mode. If it is in voltage control mode as a result of the above determination, it is started in uninterruptible power supply mode. If it is not in voltage control mode as a result of the above confirmation, it is started in voltage control mode. Converting and then starting into the uninterruptible power supply mode;
If there is no problem with the system power as a result of the determination, determining whether it is in a charging or discharging command state;
As a result of the above determination, if it is in the charging or discharging command state, it is checked whether it is in the current control mode. If it is in the current control mode as a result of the above determination, it is started in the charging mode or discharging mode. If it is not in the current control mode as a result of the above confirmation, it is switched to the current control mode. and then starting into charge mode or discharge mode; and
As a result of the determination, if it is not in a charging or discharging command state, starting in standby mode.