Power conversion device

Abstract

An auxiliary power source device according to one embodiment of the present invention generates an auxiliary power source of a power conversion device, and comprises: a first input unit into which DC power is input; a second input unit into which AC power is input; a rectification unit for converting, into DC power, the AC power input into the second input unit; and a power conversion unit connected to the first input unit and the rectification unit so as to convert the power input from the first input unit or the rectification unit and generate an auxiliary power source.

Description

power conversion device

[0001] The present invention relates to a power conversion device, and more specifically, to an auxiliary power device that efficiently generates auxiliary power for a power conversion device, and a power conversion device including the same.

[0002] Solar power generation is becoming widely adopted as an eco-friendly energy source, replacing conventional chemical and nuclear power generation. Solar power generation can be either standalone, with a battery connected to a converter, or grid-connected. Standalone systems typically consist of solar cells, storage batteries, and power conversion equipment, while grid-connected systems are connected to commercial power sources, enabling the exchange of power with load grid lines.

[0003] In grid-connected systems, power generated by solar panels is supplied to the grid via an inverter, which converts the power. This inverter requires an auxiliary power source to power it. This auxiliary power source must be supplied regardless of whether the solar panels are generating power. Therefore, technology is needed to efficiently generate this auxiliary power during times when solar power generation is not available, such as at night.

[0004] The technical problem to be solved by the present invention is to provide an auxiliary power device that efficiently generates auxiliary power for a power conversion device and a power conversion device including the same.

[0005] In order to solve the above technical problem, an auxiliary power supply device according to one embodiment of the present invention is an auxiliary power supply device that generates auxiliary power for a power conversion device, the auxiliary power supply device including: a first input unit into which DC power is input; a second input unit into which AC power is input; a rectifier unit that converts AC power input to the second input unit into DC power; and a power conversion unit connected to the first input unit and the rectifier unit, and converts power input from the first input unit or the rectifier unit to generate auxiliary power.

[0006] In addition, the power conversion unit can convert the power input from the first input unit to generate auxiliary power if the first voltage of the power input from the first input unit is higher than the second voltage of the power input from the rectifier unit.

[0007] In addition, the power conversion unit can convert the power input from the rectifier to generate auxiliary power if the first voltage of the power input from the first input unit is lower than or equal to the second voltage of the power input from the rectifier.

[0008] Additionally, the first input unit can receive power from a PV module or a battery, and the second input unit can receive power from a grid.

[0009] Additionally, the first input unit can receive power from the PV module via a DC link.

[0010] Additionally, the first input unit can receive power by being connected to the battery without going through a DC link.

[0011] In addition, it may include a first diode disposed between the first input unit and the power conversion unit, and a second diode disposed between the rectifier unit and the power conversion unit.

[0012] Additionally, the second voltage input from the rectifier to the power converter may be included within the range of the first voltage input from the first input unit.

[0013] Additionally, the power conversion unit may include a switching mode power supply (SMPS).

[0014] Additionally, the power conversion unit may include a flyback converter.

[0015] In order to solve the above technical problem, according to another embodiment of the present invention, an auxiliary power device is an auxiliary power device that generates auxiliary power for a power conversion device, the auxiliary power device including: a first input unit into which DC power is input; a second input unit into which AC power is input; a first power conversion unit that converts AC power input to the second input unit into DC power; and a second power conversion unit that is connected to the first input unit and the first power conversion unit and converts power input from the first input unit or the power conversion unit to generate auxiliary power.

[0016] In addition, the second power conversion unit can convert the power input from the first input unit to generate auxiliary power if the first voltage of the power input from the first input unit is higher than the second voltage of the power input from the first power conversion unit.

[0017] In addition, the power conversion unit can convert the power input from the first power conversion unit to generate auxiliary power if the first voltage of the power input from the first input unit is lower than or equal to the second voltage of the power input from the first power conversion unit.

[0018] In addition, it may include a sensing unit that senses the voltage of the first input unit; and a control unit that operates the first power conversion unit when the sensed voltage of the first input unit is lower than or equal to a third voltage.

[0019] In addition, the control unit can stop the operation of the first power conversion unit when the voltage of the first input unit sensed by the sensing unit is equal to or higher than the fourth voltage while the first power conversion unit is operating.

[0020] Additionally, the third voltage may be lower than the fourth voltage.

[0021] In addition, it may include a driving signal output unit that outputs a driving signal to the first power conversion unit according to an operation signal for the first power conversion unit output from the control unit.

[0022] In addition, the driving signal output unit includes a first photo coupler, and when the operating signal for the first power conversion unit is a first signal, the first photo coupler does not operate so that the first driving signal can be input to the first power conversion unit, and when the operating signal for the first power conversion unit is a second signal, the first photo coupler operates so that the second driving signal can be input to the first power conversion unit.

[0023] Additionally, the first input unit can receive power from a PV module or a battery, and the second input unit can receive power from a grid.

[0024] Additionally, the first input unit can receive power from the PV module via a DC link.

[0025] In addition, it may include a first diode disposed between the first input unit and the second power conversion unit, and a second diode disposed between the first power conversion unit and the second power conversion unit.

[0026] Additionally, the second voltage input from the first power conversion unit to the second power conversion unit may be included within the range of the first voltage input from the first input unit.

[0027] According to embodiments of the present invention, when using DC power and AC power, auxiliary power can be generated with a single SMPS. The SMPS can be operated regardless of the type of input power (AC, DC), and since operation is possible with a single SMPS, EMI noise can be reduced compared to when using multiple SMPSs. In addition, a circuit for controlling the on / off of the SMPS is not required to operate the SMPS, and thus the circuit design can be simplified. Since the SMPS is operated using high-voltage power according to the size of each input voltage (AC, DC), the switching time can be eliminated.

[0028] In addition, when AC_SMPS and DC_SMPS are included, the AC_SMPS can be turned on and off according to the DC link voltage, and when the AC_SMPS is turned on, the auxiliary power load is required only to a minimum, which has the effect of reducing the size and material cost. The output voltage of the AC_SMPS is increased and the output current is reduced, so there is the effect of reducing the component size and reducing heat generation by reducing the rated current specifications of diodes, switching elements, and filters. In addition, the auxiliary power can be stably supplied without the switching time according to the AC_SMPS on and off within the DC_SMPS operating voltage range.

[0029] Figure 1 is a block diagram of an auxiliary power supply device according to one embodiment of the present invention.

[0030] Figure 2 is a block diagram of an auxiliary power supply device according to an embodiment of the present invention.

[0031] Figures 3 and 4 are drawings for explaining an auxiliary power supply device according to an embodiment of the present invention.

[0032] Figure 5 is a block diagram of a power conversion device according to one embodiment of the present invention.

[0033] Figure 6 is a block diagram of an auxiliary power supply device according to another embodiment of the present invention.

[0034] Figure 7 is a block diagram of an auxiliary power supply device according to another embodiment of the present invention.

[0035] FIGS. 8 to 11 are drawings for explaining an auxiliary power supply device according to another embodiment of the present invention.

[0036] Figure 12 is a block diagram of a power conversion device according to another embodiment of the present invention.

[0037] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0038] However, the technical idea of ​​the present invention is not limited to some of the embodiments described, but can be implemented in various different forms, and within the scope of the technical idea of ​​the present invention, one or more of the components between the embodiments can be selectively combined or substituted for use.

[0039] In addition, terms (including technical and scientific terms) used in the embodiments of the present invention may be interpreted as having a meaning that can be generally understood by a person of ordinary skill in the technical field to which the present invention belongs, unless explicitly and specifically defined and described, and terms that are commonly used, such as terms defined in a dictionary, may be interpreted in consideration of the contextual meaning of the relevant technology.

[0040] Additionally, the terms used in the embodiments of the present invention are intended to describe the embodiments and are not intended to limit the present invention.

[0041] In this specification, the singular may also include the plural unless specifically stated otherwise in the phrase, and when it is described as “A and / or at least one (or more) of B, C”, it may include one or more of all combinations that can be combined with A, B, C.

[0042] Additionally, in describing components of embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only intended to distinguish the components from other components, and are not intended to limit the nature, order, or sequence of the components.

[0043] And, when a component is described as being 'connected', 'coupled', or 'connected' to another component, it may include not only cases where the component is 'connected', 'coupled', or 'connected' directly to the other component, but also cases where the component is 'connected', 'coupled', or 'connected' by another component between the component and the other component.

[0044] Additionally, when described as being formed or arranged "above" or "below" each component, "above" or "below" includes not only cases where the two components are in direct contact with each other, but also cases where one or more other components are formed or arranged between the two components. Furthermore, when expressed as "above" or "below," the meaning may include not only the upward direction but also the downward direction based on one component.

[0045] Variations according to the present embodiment may include some components of each embodiment and some components of other embodiments. That is, a variation may include one embodiment among various embodiments, but may omit some components and include some components of the corresponding other embodiment. Or, the opposite may be true. The features, structures, effects, etc. described in the embodiments are included in at least one embodiment and are not necessarily limited to just one embodiment. Furthermore, the features, structures, effects, etc. exemplified in each embodiment may be combined or modified in other embodiments by a person having ordinary skill in the art to which the embodiments pertain. Therefore, the contents related to such combinations and modifications should be construed as being included within the scope of the embodiments.

[0046] FIG. 1 is a block diagram of an auxiliary power supply device according to an embodiment of the present invention. FIG. 2 is a block diagram of an auxiliary power supply device according to an embodiment of the present invention. FIGS. 3 and 4 are drawings for explaining an auxiliary power supply device according to an embodiment of the present invention. FIG. 5 is a block diagram of a power conversion device according to an embodiment of the present invention.

[0047] An auxiliary power supply device (100) according to an embodiment of the present invention is composed of a first input unit (110), a second input unit (120), a rectifier unit (130), and a power conversion unit (140), and may include a first diode (141) and a second diode (142).

[0048] Solar panels generate electricity by utilizing the photovoltaic effect (PV). The photovoltaic effect occurs when light above a certain frequency strikes a metal, causing electrons to be emitted. A pn ​​junction is formed using a p-type and n-type semiconductor, and the electrons generated by the photovoltaic effect generate current, generating electricity. A solar panel comprises multiple solar cells, which are formed using materials such as silicon and can be formed in wafer form. Solar panels are located in areas with good sunlight, such as fields or on the exterior walls or rooftops of buildings, and utilize sunlight to generate electricity. In this case, solar panels can be integrated into buildings, known as building-integrated photovoltaics (BIPV).

[0049] Power generated from solar panels is converted into power suitable for the power grid and transmitted to the grid. This is done using a power conversion device. For the power conversion device to perform its power conversion function, an auxiliary power source must be supplied. For example, a power conversion device may include one or more switching elements, and for the switching elements to operate, an auxiliary power source, different from the main power source from which the power is converted, must be supplied. Additionally, auxiliary power must be supplied to the control unit, communication unit, fan, and other components.

[0050] An auxiliary power supply device according to an embodiment of the present invention includes a power conversion unit (140) for generating auxiliary power. The power conversion unit (140) generates auxiliary power using DC power or AC power.

[0051] The first input unit (110) receives DC power, and the second input unit (120) receives AC power. The first input unit (110) can receive DC power from a PV module (210) or a battery (230). The PV module (210) can include a PV panel, a converter that converts power generated by the PV panel, an optimizer that performs maximum power point tracking (MPPT), or an MLPE. The first input unit (110) can receive DC power from the PV module (210) through a DC link (240). Alternatively, the DC power can be received from the battery (230) without going through the DC link (240).

[0052] The second input unit (120) can receive AC power from the grid (220). In addition to the DC power received by the first input unit (110), the second input unit (120) can receive AC power from the grid (220) and use it to generate auxiliary power.

[0053] The rectifier (130) converts AC power input to the second input (120) into DC power.

[0054] In generating auxiliary power, the auxiliary power can be generated using one power conversion unit, and the power conversion unit (140) can be a power conversion unit that converts DC power and outputs DC power. The rectifier (130) can convert AC power input to the second input unit (120) into DC power, thereby allowing DC power to be input to the power conversion unit (140). The rectifier (130) can include one or more diodes and one or more capacitors. The rectifier (130) can include a rectifier, and the rectifier can convert AC power into DC power and input it to the power conversion unit (140).

[0055] The power conversion unit (140) is connected to the first input unit (110) and the rectifier unit (130), and converts the power input from the first input unit (110) or the rectifier unit (130) to generate auxiliary power. The first input unit (110) and the rectifier unit (130) may be connected in parallel to the power conversion unit (140), and the power conversion unit (140) may convert the power input from the first input unit (110) or the rectifier unit (130) to generate auxiliary power.

[0056] The power conversion unit (140) can generate auxiliary power using the higher voltage of the first voltage of the power input from the first input unit (110) and the second voltage of the power input from the rectifier (130).

[0057] The power conversion unit (140) can generate auxiliary power by converting the power input from the first input unit if the first voltage of the power input from the first input unit (110) is higher than the second voltage of the power input from the rectifier (130), and can generate auxiliary power by converting the power input from the rectifier if the first voltage of the power input from the first input unit is lower than the second voltage of the power input from the rectifier.

[0058] A first diode (141) may be arranged between the first input unit (110) and the power conversion unit (140), and a second diode (142) may be arranged between the rectifier (130) and the power conversion unit (140). The anode of the first diode (141) may be connected to the first input unit (110), and the cathode may be connected to the power conversion unit (140). The first diode (141) may be connected in a direction from the first input unit (110) to the power conversion unit (140), so as to allow current to flow from the first input unit (110) to the power conversion unit (140), thereby allowing power to be input, and conversely, preventing current from flowing from the power conversion unit (140) to the first input unit (110). The anode of the second diode (142) may be connected to the rectifier (130), and the cathode may be connected to the power converter (140). The second diode (142) is connected in a direction from the rectifier (130) to the power converter (140), so that current may flow from the rectifier (130) to the power converter (140), thereby allowing power to be input, and conversely, current may be prevented from flowing from the power converter (140) to the rectifier (130).

[0059] In this way, by connecting the first diode (141) and the second diode (142), the power with a higher voltage among the first voltage of the power input from the first input unit (110) and the second voltage of the power input from the rectifier (130) can be input to the power conversion unit (140), and the other power can be blocked from being input to the power conversion unit (140). For example, when the first voltage is higher than the second voltage, a voltage is applied in the forward direction to the first diode (141), and a voltage is applied in the reverse direction to the second diode (142), so that the first diode (141) can be conducted, and the second diode (142) can not allow current to flow. Through this, the output of the first input unit (110) can be input to the power conversion unit (140), and the output of the rectifier (130) can be blocked.

[0060] The PV module (210) generates power during the day, and during the day, the first voltage increases, so that the first voltage is higher than the second voltage, and at night, the first voltage decreases, so that the first voltage is lower than the second voltage. That is, during the day, the DC power, which is the power of the PV module (210), is input to the power conversion unit (140) through the first input unit (110) to generate auxiliary power, and at night, the AC power, which is the power of the grid (220), is input to the power conversion unit (140) through the second input unit (120) and the rectifier (130) to generate auxiliary power.

[0061] The second voltage input from the rectifier (130) to the power converter (140) may be included within the range of the first voltage input from the first input unit. The first voltage, which is the voltage of the power input from the PV module (210), may vary depending on the power generation amount or maximum power point tracking control of the PV module (210). Even when the first input unit (110) receives power from the battery (230), the first voltage may vary depending on the charge or discharge amount of the battery (230). In contrast, the second voltage, which is the voltage of the power input from the grid (220), may also be maintained constant since the voltage of the grid (220) is constant. Here, the second voltage may be included within the range of the first voltage. For example, the first voltage may be 100 to 600 V, and the second voltage may be approximately 311 V, which is obtained by rectifying the 220 V AC voltage of the grid. The voltage of the auxiliary power output from the power conversion unit (140) may be 15 V. Alternatively, it may vary depending on the load requiring the auxiliary power.

[0062] When the first voltage is 311 V or higher, the power conversion unit (140) generates auxiliary power using the power input from the first input unit (110), and when the first voltage is lower than 311 V, the power conversion unit (140) can generate auxiliary power using the power input from the rectifier unit (130).

[0063] The power conversion unit (140) may include a SMPS (Switching Mode Power Supply). As shown in FIG. 3, the power conversion unit (140) is implemented as an SMPS and may receive DC power from a PV module (210) via a DC link or from a battery (230). Alternatively, AC power input from a grid (220) may be converted into DC power via a rectifier to receive DC power. An SMPS (Switching Mode Power Supply) is a device that supplies power by a switching operation, and includes one or more switching elements. The SMPS may convert the voltage of the input power by PWM control of the switching elements and output power having a required voltage. The SMPS, which is the power conversion unit (140), may generate auxiliary power by converting the input DC power and supply auxiliary power required for the control unit, I / O, communication, gate driving, and fan driving.

[0064] The power conversion unit (140) may include a flyback converter. As shown in FIG. 4, it may be implemented as a flyback converter including an input capacitor (C1), a transformer (T1), a switching element (Q1), a diode (D1), and an output capacitor (C2) to generate auxiliary power. The power conversion unit (140) may include a buck converter, a boost converter, a buck-boost converter, or the like, and may include a half bridge or full bridge switching circuit.

[0065] As described above, the auxiliary power supply device (100) according to the embodiment of the present invention can generate auxiliary power with one SMPS, which is a power conversion unit (140), when using DC power and AC power. During the day, the SMPS operates with DC power generated from the PV module (210), and at night, the SMPS operates with AC power from the grid (220) or DC power from the battery (230) to generate auxiliary power. The SMPS can be operated regardless of the type of input power (AC, DC), and since operation is possible with one SMPS, EMI noise can be reduced compared to when using multiple SMPSs. In addition, by using the first diode (141) and the second diode (142), one of the two inputs is input and the other input is blocked, so that a circuit for controlling the on / off of the SMPS to operate the SMPS is not required, and through this, the circuit can be designed simply. Since the SMPS is operated using high voltage power depending on the size of each input voltage (AC, DC), the switching time can be eliminated.

[0066] A power conversion device according to an embodiment of the present invention may include, as shown in FIG. 5, a DC-DC converter for converting power from a PV module, an inverter for converting the output of the DC-DC converter input to a DC link into AC power and outputting it to a grid, and an energy storage system may be connected to the DC link. The energy storage system (ESS) may include a DC-DC converter for converting power from a battery and a DC link to charge the battery. The PV module may be connected via an MLPE, a relay as a circuit breaker may be connected between the inverter and the grid, and backup loads may be connected. The power conversion device may include an auxiliary power unit for performing power conversion and operating components. A detailed description of the auxiliary power unit corresponds to the description of the auxiliary power unit of FIGS. 1 to 4, and thus, redundant descriptions will be omitted. The auxiliary power unit may include an SMPS that is connected to the DC link, connected to the grid via a rectifier, and generates auxiliary power using DC power or AC power that is input and converted into DC power via the rectifier. The auxiliary power generated by the auxiliary power unit can supply auxiliary power required for the control unit, I / O, communications, gate drive, and fan drive. The control unit can control DC-DC converters, inverters, relays, etc., and the communications unit can communicate with MLPE or energy storage systems.

[0067] Fig. 6 is a block diagram of an auxiliary power supply device according to another embodiment of the present invention. Fig. 7 is a block diagram of an auxiliary power supply device according to another embodiment of the present invention. Figs. 8 to 11 are drawings for explaining an auxiliary power supply device according to another embodiment of the present invention. Fig. 12 is a block diagram of a power conversion device according to another embodiment of the present invention.

[0068] Among the detailed descriptions of the configuration of the auxiliary power supply according to another embodiment of the present invention, the detailed descriptions of the configuration corresponding to the auxiliary power supply of FIGS. 1 to 6 correspond to the detailed descriptions of the auxiliary power supply of FIGS. 1 to 6, and thus, any overlapping descriptions will be briefly explained below.

[0069] An auxiliary power device (300) according to another embodiment of the present invention is composed of a first input unit (110), a second input unit (120), a first power conversion unit (310), and a second power conversion unit (320), and may include a first diode (141), a second diode (142), a sensing unit (330), a control unit (340), and a driving signal output unit (not shown).

[0070] The first input unit (110) receives DC power, and the second input unit (120) receives AC power. The first input unit (110) can receive DC power from a PV module (210) or a battery (230). The PV module (210) can include a PV panel, a converter that converts power generated by the PV panel, an optimizer that performs maximum power point tracking (MPPT), or an MLPE. The first input unit (110) can receive DC power from the PV module (210) through a DC link (240). Alternatively, the DC power can be received from the battery (230) without going through the DC link (240).

[0071] The second input unit (120) can receive AC power from the grid (220). In addition to the DC power received by the first input unit (110), the second input unit (120) can receive AC power from the grid (220) and use it to generate auxiliary power.

[0072] The first power conversion unit (310) can convert AC power input to the second input unit (120) into DC power.

[0073] In generating auxiliary power, the auxiliary power can be generated using the second power conversion unit (320), and the second power conversion unit (320) can be a power conversion unit that converts DC power and outputs DC power. The first power conversion unit (310) can convert AC power input to the second input unit (120) into DC power, thereby allowing DC power to be input to the second power conversion unit (320). The first power conversion unit (310) can include a power conversion circuit that converts AC power into DC power. The first power conversion unit (310) can include a bootstrap circuit. Alternatively, it can include a buck converter, a boost converter, a buck-boost converter, etc. It can include a control unit (340) that controls the first power conversion unit (310).

[0074] The second power conversion unit (320) is connected to the first input unit (110) and the first power conversion unit (310), and converts the power input from the first input unit (110) or the first power conversion unit (310) to generate auxiliary power. The first input unit (110) and the first power conversion unit (310) may be connected in parallel to the second power conversion unit (320), and the second power conversion unit (320) may convert the power input from the first input unit (110) or the first power conversion unit (310) to generate auxiliary power.

[0075] The second power conversion unit (320) can generate auxiliary power using power having a higher voltage between the first voltage of the power input from the first input unit (110) and the second voltage of the power input from the first power conversion unit (310).

[0076] The second power conversion unit (320) can generate auxiliary power by converting the power input from the first input unit (110) if the first voltage of the power input from the first input unit (110) is higher than the second voltage of the power input from the first power conversion unit (310), and can generate auxiliary power by converting the power input from the first power conversion unit (310) if the first voltage of the power input from the first input unit (110) is lower than the second voltage of the power input from the first power conversion unit (310).

[0077] A first diode (141) may be arranged between the first input unit (110) and the second power conversion unit (320), and a second diode (142) may be arranged between the first power conversion unit (310) and the second power conversion unit (320). The anode of the first diode (141) may be connected to the first input unit (110), and the cathode may be connected to the second power conversion unit (320). The first diode (141) may be connected in a direction from the first input unit (110) to the second power conversion unit (320), so as to allow current to flow from the first input unit (110) to the second power conversion unit (320), thereby allowing power to be input, and conversely, preventing current from flowing from the second power conversion unit (320) to the first input unit (110). The anode of the second diode (142) may be connected to the first power conversion unit (310), and the cathode may be connected to the second power conversion unit (320). The second diode (142) may be connected in a direction from the first power conversion unit (310) to the second power conversion unit (320), so as to allow current to flow from the first power conversion unit (310) to the second power conversion unit (320) and input power, and conversely, may prevent current from flowing from the second power conversion unit (320) to the first power conversion unit (310).

[0078] In this way, by connecting the first diode (141) and the second diode (142), the power with the higher voltage among the first voltage of the power input from the first input unit (110) and the second voltage of the power input from the first power conversion unit (310) can be input to the second power conversion unit (320), and the other power can be blocked from being input to the second power conversion unit (320). For example, when the first voltage is higher than the second voltage, a voltage may be applied in the forward direction to the first diode (141) and a voltage may be applied in the reverse direction to the second diode (142), so that the first diode (141) may be conducted and the second diode (142) may not allow current to flow. Through this, the output of the first input unit (110) may be input to the second power conversion unit (320), and the output of the first power conversion unit (310) may be blocked.

[0079] The first power conversion unit (310) can operate as needed. When auxiliary power is generated using DC power input to the second power conversion unit (320) through the first input unit (110), the first power conversion unit (310) does not operate, thereby reducing unnecessary power consumption. To this end, the control unit (340) can control the first power conversion unit (310). The control unit (340) can operate or stop the first power conversion unit (310) depending on the magnitude of the voltage input to the first input unit (110). Under conditions where the first power conversion unit (310) does not need to operate, the operation of the first power conversion unit (310) can be stopped. The control unit (340) can use the voltage of the first input unit (110) into which power is input from the PV module (210) as a condition for determining whether to operate the first power conversion unit (310). Here, the voltage of the first input unit (110) is equal to the voltage of the DC link (240), and the control unit (340) can use the voltage of the DC link (240) to determine whether the first power conversion unit (310) operates.

[0080] Hereinafter, the control unit (340) can correspond to the case where the voltage of the DC link (240) is used when the voltage of the first input unit (110) is used, and the following description will be made based on the case where the voltage of the first input unit (110) is used.

[0081] The control unit (340) can operate the first power conversion unit (310) when the voltage of the first input unit (110) is lower than or equal to a third voltage, and can stop the operation of the first power conversion unit (310) when the voltage of the first input unit (110) is higher than or equal to a fourth voltage. The third voltage is a reference voltage at which the first power conversion unit (310) operates, and the fourth voltage is a reference voltage at which the first power conversion unit (310) stops operating. The third voltage may be lower than the fourth voltage. That is, in a situation where the second power conversion unit (320) generates auxiliary power using the power input from the first input unit (110), and the power generation of the PV module (210) is reduced due to an obstacle such as sunset or shade, the second power conversion unit (320) can generate auxiliary power using the power output from the first power conversion unit (310) rather than the first input unit (110). The reference voltage at which the first power conversion unit (310) operates can be set to the third voltage. The third voltage can be the output voltage of the first power conversion unit (310) and can be set by the user.

[0082] In a situation where the second power conversion unit (320) generates auxiliary power using the power output from the first power conversion unit (310), and the amount of power generated by the PV module (210) increases due to sunrise or the like, the auxiliary power can be generated using the power input from the first input unit (110) rather than the power output from the first power conversion unit (310). At this time, since the first power conversion unit (310) does not need to operate, the first power conversion unit (310) can stop operating and be turned off. The reference voltage at which the first power conversion unit (310) is turned off can be set to the fourth voltage. The fourth voltage can be set by the user.

[0083] At this time, the third voltage can be set lower than the fourth voltage to have a hysteresis characteristic as in Fig. 10. If the operation of the first power conversion unit (310) is determined by only one voltage, a problem may occur in which the first power conversion unit (310) is repeatedly turned on and off depending on the voltage fluctuation around the voltage, which may increase loss. By making the third voltage and the fourth voltage different so as to have a hysteresis characteristic as in Fig. 10, the repeated on and off with a small difference in voltage can be prevented. For example, the third voltage can be 150 V, and the fourth voltage can be 160 V. By making a gap of 10 V, the hysteresis characteristic can be achieved.

[0084] The control unit (340) may include a sensing unit (330), as shown in Fig. 7, to output a driving signal to the first power conversion unit (310) according to the magnitude of the voltage of the first input unit (110). In addition, the control unit (340) may include a comparator and a driving signal output unit.

[0085] The sensing unit (330) can sense the voltage of the first input unit (110). The sensing unit (330) can sense the voltage of the DC link (240) corresponding to the first input unit (110). That is, the sensing unit (330) can sense the DC voltage applied to the power conversion device.

[0086] The comparator of the control unit (340) can compare the sensed voltage of the first input unit (110) with a reference voltage. The comparator can be included in the MCU (ADC, analog to digital converter) of FIG. 8. At this time, the comparator can compare the voltage of the first input unit (110) with a third voltage or a fourth voltage. Here, the reference voltage can include the third voltage and the fourth voltage that is higher than the third voltage so as to have a hysteresis characteristic. That is, the comparator can compare whether the sensed voltage of the first input unit (110) becomes lower than the third voltage when it is higher than the fourth voltage, or becomes higher than the fourth voltage when it is lower than the third voltage.

[0087] The comparator can output a first signal when the voltage of the first input unit (110) is lower than or equal to a third voltage, and can output a second signal when the voltage of the first input unit (110) is higher than or equal to a fourth voltage. Here, the first signal can be low or 0, and the second signal can be high or 1. Alternatively, the first signal can be high, and the second signal can be low.

[0088] The driving signal output unit of the control unit (340) can output a driving signal to the first power conversion unit (310) according to the output of the comparator. The driving signal output unit can be configured as the AC_SMPS control circuit of Fig. 8. If the voltage of the first input unit (110) is lower than the third voltage, which is a reference voltage for generating auxiliary power using the output power of the first power conversion unit (310), according to the comparison result of the comparator, the driving signal output unit can output a driving signal to the first power conversion unit (310) to turn on the first power conversion unit (310).

[0089] In addition, in a situation where auxiliary power is generated with the output power of the first power conversion unit (310), if the voltage of the first input unit (110) is higher than the fourth voltage, which is the reference voltage for generating auxiliary power with the power of the first input unit (110), according to the comparison result of the comparator, the driving signal output unit can output a driving signal to the first power conversion unit (310) to turn off the first power conversion unit (310). Alternatively, the driving signal output to the first power conversion unit (310) can be blocked.

[0090] The drive signal output unit can output a first drive signal for driving the first power conversion unit (310) and a second drive signal for stopping the driving of the first power conversion unit (310). The drive signal output unit can include an Enable / Disable circuit. The first drive signal can be an enable signal and the second drive signal can be a disable signal, or conversely, the first drive signal can be a disable signal and the second drive signal can be an enable signal.

[0091] The driving signal output unit may include a first photo coupler (PC1). The photo coupler is an optical composite element including a light-emitting element and a light-receiving element, in which the light-emitting element operates to generate light and the light-receiving element operates by receiving the light generated from the light-emitting element, and may include a light-emitting diode as the light-emitting element and a transistor as the light-receiving element. The driving signal output unit may be implemented as shown in Fig. 11. When the signal of AUX_EN1, which is an output of the comparator, is a first signal, the switch Q3 is turned off, so that the first photo coupler (PC1) does not operate, and the first driving signal is input to the first power conversion unit (310), so that the first power conversion unit (310) can operate. When the output of the comparator is the second signal, the first photo coupler (820) operates to turn on the switch Q3, the first photo coupler (PC1) operates, and is connected to the ground so that the second driving signal is input to the first power conversion unit (310), thereby causing the first power conversion unit (310) to stop operating.

[0092] The drive signal output section may include a relay other than a photocoupler and may include an insulated drive signal transmission circuit.

[0093] The PV module (210) generates power during the day, and during the day, the first voltage increases, so that the first voltage is higher than the second voltage, and at night, the first voltage decreases, so that the first voltage is lower than the second voltage. That is, during the day, the DC power, which is the power of the PV module (210), is input to the second power conversion unit (320) through the first input unit (110) to generate auxiliary power, and at night, the AC power, which is the power of the grid (220), is input to the second power conversion unit (320) through the second input unit (120) and the first power conversion unit (310) to generate auxiliary power.

[0094] The second voltage output from the first power conversion unit (310) and input to the second power conversion unit (320) may be included within the range of the first voltage input from the first input unit (110). The first voltage, which is the voltage of the power input from the PV module (210), may vary depending on the power generation amount or maximum power point tracking control of the PV module (210). Even when the first input unit (110) receives power from the battery (230), the first voltage may vary depending on the charge or discharge amount of the battery (230). The second voltage, which is the voltage of the power input from the grid (220) and converted and output from the first power conversion unit (310), may be included within the range of the first voltage. For example, the first voltage may be 100 to 600 V, and the second voltage may be 150 V. When AC power from the grid is converted to DC power using only a rectifier, the second voltage is approximately 311 V. However, when using the first power conversion unit (310), the magnitude of the second voltage can be set or adjusted in various ways. This can be set by the user. The voltage of the auxiliary power output from the second power conversion unit (320) can be 15 V. Alternatively, it can vary depending on the load requiring the auxiliary power.

[0095] If the first voltage is 160 V or higher, the second power conversion unit (320) can generate auxiliary power using the power input from the first input unit (110), and if the first voltage is 150 V or lower, the second power conversion unit (320) can generate auxiliary power using the power output from the first power conversion unit (310).

[0096] The first power conversion unit (310) and the second power conversion unit (320) may include a switching mode power supply (SMPS). As shown in FIG. 8, the second power conversion unit (320) is implemented as a DC_SMPS, and may receive DC power from a PV module (210) via a DC link or receive DC power from a battery (230). In addition, the first power conversion unit (310) is implemented as an AC_SMPS, and AC power input from the grid (220) may be converted into DC power via the AC_SMPS and applied as DC power to the second power conversion unit. An SMPS (Switching Mode Power Supply) is a device that supplies power by a switching operation, and includes one or more switching elements, and may convert the voltage of the input power by PWM controlling the switching elements, and output power having a required voltage. The second power conversion unit (320), DC_SMPS, converts input DC power to generate auxiliary power, and can supply auxiliary power required for the control unit, I / O, communication, gate driving, and fan driving.

[0097] The first power conversion unit (310) may include a flyback converter including a rectifier. As shown in Fig. 9, the flyback converter may be implemented to output DC power by including a rectifier including a plurality of diodes (D2, D3, D4, D5), an input capacitor (C3), a transformer (T2), a switching element (Q2), an output-side diode (D6), and an output capacitor (C4) constituting the rectifier. The first power conversion unit (310) may include a buck converter, a boost converter, a buck-boost converter, or the like, and may include a half bridge or full bridge switching circuit.

[0098] The second power conversion unit (320) may include a flyback converter. As shown in FIG. 4, it may be implemented as a flyback converter including an input capacitor (C1), a transformer (T1), a switching element (Q1), a diode (D1), and an output capacitor (C2) to generate auxiliary power. The second power conversion unit (320) may include a buck converter, a boost converter, a buck-boost converter, or the like, and may include a half bridge or full bridge switching circuit.

[0099] As described above, the auxiliary power supply device (300) according to the embodiment of the present invention can supply auxiliary power by operating the DC_SMPS with the DC power generated from the PV module (210) during the day. At this time, the AC_SMPS can be turned off through the AC_SMPS control circuit that senses the voltage of the DC link (240) and turns off the AC_SMPS, which is the first power conversion unit (310), when the voltage of the first input unit (110) is 160 V or higher, which is the fourth threshold voltage. At night (Night mode), the AC_SMPS, which is the first power conversion unit (310) that inputs grid AC power, operates and supplies its output as input to the DC_SMPS, which is the second power conversion unit (320), and the DC_SMPS supplies auxiliary power. If the voltage of the first input unit (110) supplied from the battery (230) is 160 V or higher, which is the fourth voltage, only the DC_SMPS operates, and when the voltage is 150 V or lower, which is the third voltage, the AC_SMPS, which is the first power conversion unit (310), operates to supply the input voltage of the DC_SMPS, which is the second power conversion unit (320). The AC_SMPS can be turned on and off according to the DC link voltage supplied from the PV module (210) and the battery (230), and when the AC_SMPS is turned on, since there is no voltage from the PV module (210) or the battery (230), the load of the auxiliary power source is required only to a minimum, which has the effect of reducing the size and material cost. Since the output voltage of the AC_SMPS is increased and the output current is reduced, there is the effect of reducing the size of components and reducing heat generation by reducing the rated current specifications of diodes, switching elements, and filters. In addition, it is possible to stably supply auxiliary power without switching time due to AC_SMPS on / off within the DC_SMPS operating voltage range of 100 to 600 V.

[0100] According to another embodiment of the present invention, a power conversion device may include, as shown in FIG. 12, a DC-DC converter for converting power from a PV module, an inverter for converting the output of the DC-DC converter input to a DC link into AC power and outputting it to a grid, and an energy storage system may be connected to the DC link. The energy storage system (ESS) may include a DC-DC converter for converting power from a battery and a DC link to charge the battery. The PV module may be connected via an MLPE, a relay, which is a circuit breaker, may be connected between the inverter and the grid, and backup loads may be connected. The power conversion device may include an auxiliary power unit for performing power conversion and operating components. A detailed description of the auxiliary power unit corresponds to the description of the auxiliary power unit of FIGS. 6 to 11, and thus, redundant descriptions will be omitted. The auxiliary power supply unit may include a DC_SMPS that is connected to a DC link, connected to a grid through a first power conversion unit, an AC_SMPS, and generates auxiliary power using DC power or AC power converted into DC power through the AC_SMPS and input. The auxiliary power generated by the auxiliary power supply unit may supply auxiliary power required for a control unit, I / O, communication, gate driving, and fan driving. The control unit may control a DC-DC converter, an inverter, a relay, etc., and the communication unit may communicate with an MLPE or an energy storage system.

[0101] Those skilled in the art will appreciate that the present invention can be implemented in modified forms without departing from the essential characteristics of the above-described description. Therefore, the disclosed methods should be considered illustrative rather than restrictive. The scope of the present invention is set forth in the claims, not the foregoing description, and all differences within the scope equivalent thereto should be construed as being encompassed by the present invention.

Claims

1. In an auxiliary power device that generates auxiliary power for a power conversion device, A first input terminal into which DC power is input; A second input terminal into which AC power is input; A rectifier that converts AC power input to the second input unit into DC power; and An auxiliary power device including a power conversion unit that is connected to the first input unit and the rectifier and converts power input from the first input unit or the rectifier to generate auxiliary power.

2. In paragraph 1, The above power conversion unit, An auxiliary power device that converts power input from the first input unit to generate auxiliary power when the first voltage of the power input from the first input unit is higher than the second voltage of the power input from the rectifier.

3. In paragraph 1, The above power conversion unit, An auxiliary power device that converts power input from the rectifier to generate auxiliary power when the first voltage of the power input from the first input unit is lower than or equal to the second voltage of the power input from the rectifier.

4. In paragraph 1, The above first input section receives power from a PV module or a battery, The above second input unit is an auxiliary power supply device that receives power from the grid.

5. In paragraph 4, The above first input section, An auxiliary power supply that receives power from the PV module via a DC link.

6. In paragraph 4, The above first input section, An auxiliary power supply that receives power from the battery without going through a DC link.

7. In paragraph 1, Including a first diode arranged between the first input unit and the power conversion unit, An auxiliary power supply device including a second diode arranged between the rectifier and the power converter.

8. In paragraph 1, An auxiliary power device in which the second voltage input from the rectifier to the power converter is within the range of the first voltage input from the first input unit.

9. In paragraph 1, The above power conversion unit is an auxiliary power device including a SMPS (Switching Mode Power Supply).

10. In paragraph 1, The above power conversion unit is an auxiliary power supply device including a flyback converter.

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