Power converter and optical storage and charging system

Abstract

The invention discloses a power converter and an optical storage and charging system. In the power converter, one end of a direct-current bus capacitor is connected with the direct-current end of the power converter used for being connected with a direct-current power supply, the other end of the direct-current bus capacitor is connected with the direct-current end of an inverter circuit, and the alternating-current end of the inverter circuit is connected with an alternating-current circuit through an alternating-current relay; the input end and the output end of the auxiliary power supply circuit are respectively connected with the direct-current bus capacitor and the power supply end of the first control circuit so as to provide target direct current for the first control circuit by utilizing direct current of the direct-current bus capacitor; and in response to the electrical signal of the direct-current end of the power converter being smaller than the preset threshold value and the alternating-current circuit being electrified, closing the alternating-current relay to take power from the alternating-current circuit through the alternating-current relay to supply power to the direct-current bus capacitor. According to the mode, the number of devices of the power converter is effectively reduced, so that the cost is reduced, the layout space of a PCB is saved, and meanwhile, the charging power of the direct-current bus capacitor and the power of the auxiliary power supply circuit are improved.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and more specifically, to a power converter and a photovoltaic energy storage and charging system. Background Technology

[0002] Power converters, as key devices capable of converting power between direct current (DC) and alternating current (AC), are widely used in new energy, electric vehicles, and industrial power supplies. To ensure the normal operation of the power converter, an auxiliary power supply circuit is typically included in the control circuit. This auxiliary power supply circuit, specifically the DC auxiliary power supply circuit, provides the target DC power to the control circuit based on the DC power supplied by the DC bus capacitor connected to the DC terminal of the power converter.

[0003] To prevent the DC power output from the DC power supply from failing to power the DC bus capacitor, thus causing the control circuit to malfunction, related technologies may include an AC auxiliary power supply circuit within the auxiliary power supply circuit. This AC auxiliary power supply circuit draws power from the AC circuit to power the control circuit. However, the AC auxiliary power supply circuit has more components and lower power, which not only increases the overall cost of the auxiliary power supply circuit and the PCB layout space, but also limits the charging power of the DC bus capacitor connected to the downstream circuit and the overall power of the auxiliary power supply circuit. Summary of the Invention

[0004] This application provides a power converter and an optical energy storage and charging system. The various aspects involved in this application embodiment are described below.

[0005] In a first aspect, a power converter is provided, comprising: a DC bus capacitor, an auxiliary power supply circuit, an inverter circuit, an AC relay, and a first control circuit, wherein: one end of the DC bus capacitor is connected to the DC terminal of the power converter, the DC terminal of the power converter is used to connect to a DC power supply, the other end of the DC bus capacitor is connected to the DC terminal of the inverter circuit, the AC terminal of the inverter circuit is connected to one end of the AC relay, and the other end of the AC relay is used to connect to an AC circuit; the input terminal of the auxiliary power supply circuit is connected to the DC bus capacitor, the output terminal of the auxiliary power supply circuit is connected to the power supply terminal of the first control circuit, and the auxiliary power supply circuit uses the DC current of the DC bus capacitor to provide a target DC current to the first control circuit; in response to the electrical signal at the DC terminal of the power converter being less than a preset threshold and the AC circuit being energized, the AC relay is closed to draw power from the AC circuit through the AC relay to supply power to the DC bus capacitor.

[0006] As one possible implementation, the power converter further includes: a rectifier circuit, the input terminal of which is connected to one end of the AC relay, and the output terminal of which is connected to one end of the DC bus capacitor. In response to the closing of the AC relay, the rectifier circuit converts the AC power obtained by the AC relay from the AC circuit into DC power to supply power to the DC bus capacitor.

[0007] As one possible implementation, the rectifier circuit is a rectifier bridge.

[0008] As one possible implementation, the rectifier circuit is formed by the body diode of the switching transistor of the inverter circuit.

[0009] As one possible implementation, the AC relay includes a primary AC relay, which includes a primary AC control coil and a primary controllable contact. Both ends of the primary AC control coil are connected to the AC circuit. One end of the primary controllable contact is connected to the input terminal of the rectifier circuit, and the other end is used to connect to the AC circuit.

[0010] As one possible implementation, the power converter further includes: a DC relay, comprising a DC control coil and a normally closed contact, wherein the DC control coil is connected to a second control circuit, and the normally closed contact is connected in series between the primary AC control coil and the AC circuit, wherein the second control circuit is used to provide DC power to the DC control coil when the electrical signal at the DC terminal of the power converter is greater than or equal to the preset threshold, so as to disconnect the normally closed contact and the primary controllable contact.

[0011] As one possible implementation, the primary AC relay includes: a first primary AC relay, comprising a first primary AC control coil and a first primary controllable contact, one end of the first primary AC control coil being connected to a first phase circuit in the AC circuit, and the other end of the first primary AC control coil being connected to a second phase circuit in the AC circuit via the normally closed contact; one end of the first primary controllable contact being connected to the input terminal of the rectifier circuit, and the other end of the first primary controllable contact being connected to the first phase circuit; and a second primary AC relay, comprising a second primary AC control coil and a second primary controllable contact, one end of the second primary AC control coil being connected to the first phase circuit in the AC circuit, and the other end of the second primary AC control coil being connected to a second phase circuit in the AC circuit via the normally closed contact; one end of the second primary controllable contact being connected to the input terminal of the rectifier circuit, and the other end of the second primary controllable contact being connected to the second phase circuit.

[0012] As one possible implementation, the AC relay further includes a secondary AC relay, wherein one end of the primary controllable contact is connected to the input terminal of the rectifier circuit through the secondary controllable contact of the secondary AC relay.

[0013] As one possible implementation, the power converter also includes a soft-start circuit connected to the AC relay.

[0014] As one possible implementation, the soft-start circuit includes a soft-start relay and a soft-start resistor, wherein the soft-start relay and the soft-start resistor are connected in series.

[0015] As one possible implementation, in response to the AC circuit drawing power from the AC circuit to supply power to the DC bus capacitor via the AC relay and the power converter malfunctioning, the first control circuit sends an abnormality warning signal to the central control unit and controls the AC relay to turn off.

[0016] As one possible implementation, in response to a power converter malfunction and power being drawn from the AC circuit via the AC relay to supply power to the DC bus capacitor, the first control circuit controls the secondary AC relay to turn off and controls the primary AC relay to close, so as to utilize the primary AC relay to draw power from the AC circuit to supply power to the DC bus capacitor.

[0017] In a second aspect, a photovoltaic-storage-charging system is provided, comprising: a DC power supply, including a photovoltaic panel and / or a photovoltaic storage battery, for providing DC power; and a power converter as described in the first aspect, connected to the DC power supply and an AC circuit respectively, the power converter being used to perform power conversion between the DC power supply and the AC circuit.

[0018] The power converter provided in this application embodiment can close an AC relay originally used to control the connection and disconnection between the inverter circuit and the AC circuit when the electrical signal at the DC terminal of the power converter is less than a preset threshold and the AC circuit is energized. This allows power to be drawn from the AC circuit through the closed AC relay to supply power to the DC bus capacitor in the power converter, thereby powering the auxiliary power supply circuit connected to the downstream of the DC bus capacitor. This method is equivalent to using the characteristics of the AC relay to draw power from the AC circuit to supply power to the DC bus capacitor. It not only utilizes the characteristics of the AC relay to achieve isolation but also helps to eliminate the DC-DC converter circuit in the AC auxiliary power supply circuit of related technologies, and even eliminates the entire AC auxiliary power supply circuit, effectively reducing the number of components in the power converter, thereby reducing costs and saving PCB layout space. Furthermore, since the charging power of the DC bus capacitor and the power of the auxiliary power supply circuit are no longer limited by the power of the AC auxiliary power supply circuit, it is beneficial to improve the charging power of the DC bus capacitor and the power of the auxiliary power supply circuit. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a power converter in related technologies.

[0020] Figure 2 This is a schematic diagram of the power converter provided in one embodiment of this application.

[0021] Figure 3 This is a schematic diagram of the power converter provided in another embodiment of this application.

[0022] Figure 4 This is a schematic diagram of the power converter provided in another embodiment of this application.

[0023] Figure 5 This is a schematic diagram of the power converter provided in another embodiment of this application.

[0024] Figure 6 This is a schematic diagram of the power converter provided in another embodiment of this application.

[0025] Figure 7 This is a schematic diagram of the power converter provided in another embodiment of this application.

[0026] Figure 8 This is a schematic diagram of the power converter provided in another embodiment of this application.

[0027] Figure 9 This is a schematic diagram of the power converter provided in another embodiment of this application.

[0028] Figure 10 This is a schematic diagram of the power converter provided in another embodiment of this application.

[0029] Figure 11 This is a schematic diagram of the power converter provided in another embodiment of this application.

[0030] Figure 12 This is a schematic diagram of the power converter provided in another embodiment of this application.

[0031] Figure 13 This is a schematic diagram of the power converter provided in another embodiment of this application.

[0032] Figure 14 This is a schematic diagram of the power converter provided in another embodiment of this application.

[0033] Figure 15 yes Figures 12-14 A schematic diagram of the inverter circuit. Detailed Implementation

[0034] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present application should fall within the scope of protection of the present application.

[0035] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0036] Power converters, as key devices capable of converting power between direct current and alternating current, are widely used in new energy, electric vehicles, industrial power supplies, and other fields.

[0037] For example, power converters are widely used in photovoltaic energy storage and charging systems. A power converter includes a DC terminal and an AC terminal. The DC terminal of the power converter is used to connect to a DC power supply, and the DC terminal of the power converter is connected to the DC bus capacitor (e.g., ...). Figure 1 One side of C1) is connected to power the DC bus capacitor using DC power supplied by a DC power source. The DC power source is, for example, a photovoltaic energy storage module, and the photovoltaic energy storage module may include, for example, a... Figure 1 The diagram shows a photovoltaic (PV) panel and / or a photovoltaic storage battery. The AC terminal of the power converter is equipped with an inverter circuit for connection to an AC circuit (e.g., the power grid) and / or an AC load.

[0038] To ensure the normal operation of the power converter, an auxiliary power supply circuit (or simply auxiliary power source) is typically provided for the control circuit in the power converter to supply power to the control circuit. The control circuit can be understood as the control center in the power converter used to specify or execute control logic for controlling the power converter. For example, the control circuit may include a controller. For example, the control circuit is used to determine whether to connect to the grid or disconnect from the grid based on preset control logic. For another example, the control circuit is used to determine whether the power converter has successfully started up based on preset control logic. For yet another example, the control circuit is also used to control fans, displays, etc., to perform related operations. It should be noted that, to distinguish it from some embodiments described later in this application, the control circuit described here may be referred to as the first control circuit in the following text.

[0039] The auxiliary power source usually includes a DC auxiliary power supply circuit (referred to as DC auxiliary power source or DC auxiliary power source). The input terminal of the DC auxiliary power source is connected to the DC bus capacitor, and the output terminal of the DC auxiliary power source is connected to the power supply terminal of the first control circuit. Based on this, the DC auxiliary power source can draw DC power from the DC bus capacitor to provide the target DC power to the first control circuit, and the DC power in the DC bus capacitor mainly comes from the DC power supply.

[0040] However, in some scenarios, the electrical signal at the DC end of the power converter cannot charge the DC bus capacitor, or in other words, the electrical signal output by the DC power supply may not be sufficient to charge the DC bus capacitor. For example, if the DC power supply only includes a photovoltaic storage battery, and the battery is low on charge or even depleted, the output signal will be less than a preset threshold. Similarly, if the DC power supply includes a photovoltaic panel and a photovoltaic storage battery, and the battery is depleted and it is nighttime (or during prolonged cloudy or rainy weather), the output signals from both the photovoltaic panel and the storage battery will be less than a preset threshold. This preset threshold could be, for example, the minimum voltage or current required to charge the DC bus capacitor. Because the DC bus capacitor cannot be charged, it will prevent power from being supplied to the DC auxiliary power source and the first control circuit at the downstream end of the DC power supply.

[0041] To prevent the DC bus capacitor, DC auxiliary power source, and first control circuit from malfunctioning due to the DC terminal electrical signal of the power converter being less than a preset threshold, in related technologies, an AC auxiliary power supply circuit (referred to as AC auxiliary power source or (Alternating Current, AC) auxiliary power source) can be provided in the auxiliary power source to draw power from the AC circuit to supply power to the DC bus capacitor, so that the DC bus capacitor can supply power to the downstream DC auxiliary power source and the first control circuit.

[0042] However, AC auxiliary power sources not only have more components, leading to higher costs and increased PCB layout space, but most AC auxiliary power sources also have relatively low power, which limits the charging power of the DC bus capacitor connected to the back end and the overall power of the auxiliary power source.

[0043] To make it easier to understand, the following will be combined with... Figure 1 An exemplary description is provided for a power converter 100 in the related art and an auxiliary source 110 applied in the power converter 100.

[0044] like Figure 1 As shown, the power converter 100 includes a DC bus capacitor C1, an auxiliary power source 110, and a first control circuit 120.

[0045] DC bus capacitor C1 and used to connect DC power supply ( Figure 1 The DC terminal of the power converter (containing PV and battery) is connected to obtain the DC power output from the DC power supply of the power converter.

[0046] The auxiliary power source 110 includes an AC auxiliary power source 111 and a DC auxiliary power source 112. The AC auxiliary power source 111 includes a rectifier circuit 113 and a DC-DC (DCDC) converter circuit 114 (abbreviated as DCDC114).

[0047] The input terminal of rectifier circuit 113 is connected to the AC circuit, and the output terminal of rectifier circuit 113 is connected to the input terminal of DC-DC converter 114. Rectifier circuit 113 is used to convert AC power in AC circuit into DC power. For example, rectifier circuit 113 is a rectifier bridge.

[0048] The output terminal of DCDC114 is connected to the DC terminal of the power converter. DCDC114 provides isolation for the AC auxiliary power source 111 to meet safety requirements. Secondly, DCDC114 also converts the DC voltage output from the rectifier circuit 113 from a first voltage to a second voltage. In this embodiment, since DCDC114 is located at the AC terminal of the power converter and provides isolation, DCDC114 is an isolated DCDC converter circuit.

[0049] This application does not specifically limit the type of DC-DC114, as long as DC-DC114 is an isolated DC-DC. For example, DC-DC114 can be one of the following circuits: an isolated boost DC-DC, an isolated buck DC-DC, and an isolated buck-boost DC-DC.

[0050] As an example, see [link / details]. Figure 1 The DC-DC converter 114 may include an isolation transformer T2. The primary side of T2 includes a primary winding and an input capacitor C11, with both ends of the primary winding and the input capacitor C11 connected to the output of a rectifier circuit 113 to obtain the input voltage from the rectifier circuit 113. The secondary side of T2 includes a secondary winding, a rectifier diode D11, and an output capacitor C12. The secondary side has an output terminal used to provide the output voltage V to the DC terminal of the power converter. out_AC-DC .

[0051] The DC-DC114 may further include a controllable switch Q11 and a voltage regulation circuit 115 connected to the primary side. The controllable switch Q11 controls the primary side's on / off state. The voltage regulation circuit 115 is connected to both the output terminal of the secondary side and the control terminal of the controllable switch Q11. The voltage regulation circuit 115 can be used to monitor the output voltage V. out_AC And based on the detected output voltage V out_AC Controlling the on and off times of the controllable switch Q11 to make the output voltage V out_ACThe voltage is stabilized at a preset value. For example, the voltage regulation circuit 115 may include a PWM controller 116, a reference voltage supply circuit, an optocoupler 117, etc. The isolation transformer T2 and the optocoupler 117 together enable the AC auxiliary power supply 111 to have isolation function.

[0052] The PWM controller 116 can be connected to one end of the input capacitor C11, the output terminal of the optocoupler 117, and the control terminal of the controllable switch Q11 to control the output voltage V. out_AC-DC The PWM controller 116 controls the on and off times of the controllable switch Q11. In some embodiments, the PWM controller 116 can be connected to one end of the input capacitor C11 via a resistor R11.

[0053] The reference voltage supply circuit consists of resistors R14, R15, and R13, as well as a voltage reference V. REF composition.

[0054] The power inverter has three input terminals and one output terminal on its DC side. These three input terminals are connected to the output terminals of the PV panel, the photovoltaic storage battery, and the AC auxiliary power source 111 (i.e., the output terminal of DC-DC converter 114), respectively. The output terminal is connected to the DC bus capacitor C1, which is also connected to the input terminal of the DC auxiliary power source 112 to supply power to it. The output terminal of the powered DC auxiliary power source 112 is connected to the first control circuit to provide the target DC power to the first control circuit. This application does not specifically limit the circuit structure of the DC auxiliary power source 112; for ease of understanding, please refer to the auxiliary power supply circuit structure described later.

[0055] From the above, it can be seen that: First, the AC auxiliary power source 111 in the related technology includes both a rectifier circuit 113 and a DC-DC converter circuit 114, and the DC-DC converter circuit 114 is relatively complex. Therefore, the AC auxiliary power source 111 has many components, which leads to a higher overall cost of the power converter 100 and increases the layout space of the PCB board where the power converter 100 is located. Second, although the AC auxiliary power source 111 in the related technology can provide power to the first control circuit of the power converter when the DC power supply is not outputting power, due to the large number of components in the AC auxiliary power source 111... Due to cost and other constraints, the power of the DC-DC converter circuit 114 is relatively small, resulting in a small overall power of the AC auxiliary power source 111. This limits the charging power of the DC bus capacitor connected to the downstream side and the power of the DC auxiliary power source 112. Even when the existing AC auxiliary power source 111 is used to directly power the DC bus capacitor C1, the power consumption is large, causing the DC bus to collapse during the startup of the power converter. Therefore, due to the small power of the AC auxiliary power source 111 in the relevant technology, it is difficult to effectively establish the DC bus voltage until the photovoltaic inverter is started up.

[0056] In summary, in related technologies, AC auxiliary power supplies have many components and relatively low power, which not only leads to high costs and increased PCB layout space, but also limits the charging power of the DC bus capacitor connected to the back end and the overall power of the auxiliary power supply circuit.

[0057] In view of this, the power converter provided in this application can control the AC relay originally used to control the on / off connection between the inverter circuit and the AC circuit to close when the electrical signal at the DC terminal of the power converter is less than a preset threshold and the AC circuit is energized. This allows power to be drawn from the AC circuit through the closed AC relay to supply power to the DC bus capacitor in the power converter, thereby supplying power to the auxiliary power supply circuit connected to the downstream of the DC bus capacitor. This method is equivalent to using the characteristics of the AC relay to draw power from the AC circuit to supply power to the DC bus capacitor. It not only utilizes the characteristics of the AC relay to achieve isolation, but also helps to eliminate the DC-DC converter circuit in the AC auxiliary power supply circuit of related technologies, and even eliminates the entire AC auxiliary power supply circuit, effectively reducing the number of components in the overall auxiliary power supply circuit, thereby reducing costs and saving PCB layout space. Simultaneously, since the charging power of the DC bus capacitor and the power of the auxiliary power supply circuit are no longer limited by the power of the AC auxiliary power supply circuit, it is beneficial to improve the charging power of the DC bus capacitor and the power of the auxiliary power supply circuit.

[0058] The following is combined Figure 2 The power converter 200 provided in the embodiments of this application will be described in more detail.

[0059] like Figure 2 As shown, the power converter 200 includes a main power circuit and an auxiliary circuit. The main power circuit includes a DC bus capacitor C1, an inverter circuit 220, and an AC relay 230. The auxiliary circuit includes an auxiliary power supply circuit 240 and a first control circuit 241.

[0060] As previously described, the power converter 200 may include a DC terminal for connection to a DC power supply, and the DC terminal of the power converter is connected to one end of the DC bus capacitor C1 to power the DC bus capacitor C1 using the DC power supplied by the DC power supply. The DC power supply may include a PV and / or an energy storage battery. Specifically, the DC terminal of the power converter 200 may include, for example, a DC terminal for connection to a DC power supply. Figure 11 The PV DC terminal and the battery DC terminal shown are used to connect to the PV panel and the battery DC terminal is used to connect to the energy storage battery.

[0061] Optionally, such as Figure 2 As shown, the DC terminal of the power converter 200 can be equipped with a DC-DC conversion circuit 210, which is connected to the DC bus capacitor C1. Specifically, as shown... Figure 2As shown, the input terminal of the DC-DC converter circuit 210 is connected to the DC power supply, and the output terminal of the DC-DC converter circuit 210 is connected to one end of the DC bus capacitor C1.

[0062] See details Figure 2 The power converter may also include an AC terminal, which is equipped with an inverter circuit 220 for connection to an AC circuit (e.g., the power grid) and / or an AC load. Specifically, the inverter circuit 220 also includes a DC terminal and an AC terminal. The other end of the DC bus capacitor C1 is connected to the DC terminal of the inverter circuit 220, and the AC terminal of the inverter circuit 220 is connected to the AC circuit via an AC relay 230. That is, the AC terminal of the inverter circuit 220 is connected to one end of the AC relay 230, and the other end of the AC relay 230 is used to connect to the AC circuit. The on / off state of the AC relay 230 is used to control the connection state between the inverter circuit 220 and the AC circuit. For example, when the AC relay 230 is closed, the inverter circuit 220 is connected to the AC circuit, which can also be considered a grid-connected state; when the AC relay 230 is open, the inverter circuit 220 is disconnected from the AC circuit, which can also be considered an off-grid state. In some embodiments, the AC relay 230 may also be referred to as a relay for main power control.

[0063] In this embodiment, the AC relay 230 can be understood as a relay used in an alternating current (AC) circuit, or, in other words, a relay controlled based on AC power. In this embodiment, the AC relay 230 is connected to an AC circuit and can close in response to the AC circuit being energized. Therefore, the AC relay 230 in this embodiment can be understood as a relay that closes (or is activated) when AC power is applied. In some embodiments, the AC relay 230 consists of an AC control coil and controllable contacts; or, the AC relay 230 includes an AC control coil and controllable contacts. The AC control coil is connected to the AC circuit to allow AC power to flow, thereby changing the state of the controllable contacts. The AC circuit is, for example, a power grid. One end of the controllable contact is connected to a DC bus capacitor C1, and the other end of the controllable contact can be connected to the AC circuit.

[0064] It should be noted that, in this embodiment, the so-called AC-energized relay is an AC relay where the controllable contacts will be in a closed state as long as AC current flows through the AC control coil. The presence of AC current in the AC control coil is achieved autonomously by the relay itself, without the need for control from other energized devices. In other words, in this embodiment, the controllable contacts are open when the AC control coil is not energized. When AC current flows through the AC control coil, the relay, according to its own control logic, closes the controllable contacts to connect the rectifier circuit 250 to the AC circuit.

[0065] The auxiliary power supply circuit 240 can be understood as a DC auxiliary power source in related technologies. The input terminal of the auxiliary power supply circuit 240 is connected to the DC bus capacitor C1, and the output terminal of the auxiliary power supply circuit 240 is connected to the power supply terminal of the first control circuit 241. Based on this, the auxiliary power supply circuit 240 can draw DC power from the DC bus capacitor C1 to provide the target DC power to the first control circuit 241.

[0066] Based on the characteristic that the AC relay 230 activates when AC power is applied, in this embodiment, the power converter 200 can close the AC relay 230 when the electrical signal at the DC terminal of the power converter 200 is less than a preset threshold and the AC circuit is energized. This allows the AC relay 230 to draw power from the AC circuit to supply power to the DC bus capacitor, thereby enabling the use of the DC bus capacitor to power the auxiliary power supply circuit 240 and the first control circuit 241. In other words, in this embodiment, when the electrical signal provided by the DC power supply to the DC terminal of the power converter 200 is less than a preset threshold, the characteristic that the AC relay 230 connected to the inverter circuit 220 activates when AC power is applied allows the AC relay 230 to automatically activate. This allows the AC current in the AC circuit to be transmitted to the DC bus capacitor C1 via the AC relay 230, thus enabling the use of the DC power in the DC bus capacitor C1 to power the auxiliary power supply circuit 240, and then using the auxiliary power supply circuit 240 to provide the target DC power to the first control circuit 241.

[0067] Since the embodiments of this application are equivalent to reusing the AC relay in the main power circuit to power the auxiliary circuit, and due to the characteristics of the AC relay 230 in the embodiments of this application, it can provide isolation. Therefore, the AC relay can be used to replace the DC-DC converter circuit in the AC auxiliary power circuit of the related technology, which is equivalent to eliminating the DC-DC converter circuit in the AC auxiliary power circuit of the related technology. This is even beneficial to eliminate the entire AC auxiliary power circuit, effectively reducing the number of components in the overall auxiliary power circuit, thereby reducing costs and saving PCB layout space. At the same time, since the charging power of the DC bus capacitor and the power of the auxiliary power circuit are no longer limited by the power of the AC auxiliary power circuit, it is beneficial to improve the charging power of the DC bus capacitor and the power of the auxiliary power circuit.

[0068] To further convert the AC power obtained from the AC circuit by the AC relay 230 into DC power capable of charging the DC bus capacitor, in some embodiments, such as Figure 3 As shown, the power converter 200 may also include a rectifier circuit 250. The rectifier circuit 250 is used to convert the alternating current flowing through the alternating current relay 230 into direct current when the alternating current relay 230 is closed.

[0069] Specifically, the rectifier circuit 250 includes an input terminal and an output terminal. The input terminal of the rectifier circuit 250 is connected to one end of the AC relay 230, and the output terminal of the rectifier circuit 250 is connected to one end of the DC bus capacitor C1. In some embodiments, the output terminal of the rectifier circuit 250 includes a first output terminal and a second output terminal, which are connected in parallel with the DC bus capacitor C1. In response to the closure of the AC relay 230, the rectifier circuit 250 converts the AC power obtained by the AC relay 230 from the AC circuit into DC power to supply power to the DC bus capacitor C1.

[0070] As mentioned above, the AC relay 230 can be composed of an AC control coil and controllable contacts. Based on this, one end of the controllable contact can be connected to the input terminal of the rectifier circuit 250, so as to be connected to the DC bus capacitor C1 through the rectifier circuit 250, and the other end of the controllable contact of the rectifier circuit 250 is connected to the AC circuit.

[0071] In this embodiment, the AC auxiliary power source in the related technology can be replaced by an AC relay 230 and a rectifier circuit 250 to enable power to be drawn from the AC circuit to supply power to the DC bus capacitor C1 when the AC circuit is energized. In addition, since the DC-DC converter circuit in the related technology is eliminated, the power of the rectifier circuit 250 is no longer limited by the power of the DC-DC converter circuit. The power supply circuit formed by the AC relay 230 and the rectifier circuit 250 is sufficient to establish the DC bus voltage using AC power when the AC circuit is energized. This not only reduces the number of components to reduce costs and saves PCB layout space, but also avoids the problem of the DC bus voltage not being able to be established due to the absence or depletion of DC power supply.

[0072] This application does not impose specific limitations on the rectifier circuit 250. It is sufficient that the rectifier circuit 250 can convert AC power to DC power.

[0073] As one implementation method, such as Figure 11 As shown, the rectifier circuit 250 is a rectifier bridge. The rectifier bridge can be, for example, similar to the rectifier bridge in the AC auxiliary power source described above. The rectifier bridge can consist of two pairs of electronic components, each pair forming a "bridge" connection. During rectification, one pair of electronic components is in a conducting state, while the other pair is in a cut-off state. This application does not specifically limit the type of rectifier bridge. For example, the rectifier bridge can be a full-bridge rectifier bridge. Alternatively, it can be a half-bridge rectifier bridge. By retaining only the rectifier bridge in the AC auxiliary power source as the rectifier circuit 250, the number of components can be reduced while ensuring the function of converting AC to DC. Furthermore, since this application eliminates the DC-DC conversion circuit in the AC auxiliary power source of related technologies, the power of the rectifier bridge selected in this application embodiment can be much greater than the power of the rectifier bridge in the AC auxiliary power source of related technologies, thereby improving the charging power of the DC bus capacitor C1 and the power of the auxiliary power supply circuit.

[0074] As another implementation, the rectifier circuit 250 is formed by the inverter circuit 220, based on which, Figures 4-10 In this circuit, rectifier circuit 250 is the same as inverter circuit 220. Specifically, as shown in... Figures 12-14As shown, the rectifier circuit 250 is formed by the body diode of the switching transistor in the inverter circuit 220. That is, the body diode of the switching transistor in the inverter circuit 220 can be used to construct a rectifier circuit 250 for converting AC to DC. In the power converter 200, the inverter circuit 220 can be used to convert DC to AC to enable grid-connected operation of the energy storage module or to supply the energy of the energy storage module to an AC load. The switching transistor in the inverter circuit 220 can be a semiconductor device. For example, the switching transistor in the inverter circuit 220 can be a MOSFET or an IGBT. The body diode is an anti-parallel diode inside the switching transistor in the inverter circuit 220. The structural characteristics of the body diode determine that when the switching transistor is off, the body diode can conduct current unidirectionally. For example, when the switching transistor in the inverter circuit 220 is a MOSFET, the body diode is located between the source and drain of the MOSFET, and when the MOSFET is off, the body diode allows current to flow from the source to the drain.

[0075] This application does not specifically limit the structure of the inverter circuit 220 in the embodiments. As an example, such as Figure 15 As shown, inverter circuit 220 is a full-bridge inverter circuit. Inverter circuit 220 includes six switching transistors (Q21, Q22, Q23, Q24, Q25, and Q26) and their respective body diodes (D21, D22, D23, D24, D25, and D26). Under normal operating conditions, i.e., when the energy storage module has a DC output and the inverter circuit 220 is used to convert the DC output from the energy storage module into AC, inverter circuit 220 generates AC output voltage by controlling the on / off state of switching transistors Q21, Q22, Q23, Q24, Q25, and Q26. Specifically, when Q21 and Q24 are turned on, current flows from the positive terminal of the power supply through Q21 to the load, and then returns to the negative terminal of the power supply through Q24, forming a current path in one direction. When Q22 and Q23 are turned on, current flows from the positive terminal of the power supply through Q23 to the load, and then back to the negative terminal of the power supply through Q22, forming a current path in the opposite direction. By alternately controlling the on and off of these two sets of switches, an alternating voltage waveform can be generated across the load, thereby achieving DC to AC conversion. Q25 and Q26 are connected in series, and the two ends of the series circuit are connected to the first and second phase circuits respectively, so that current can flow through the protection circuit in the event of a load short circuit.

[0076] By reusing the body diode of the switching transistor in the inverter circuit 220 to form the rectifier circuit 250, the inverter circuit 220 and the AC relay 230 can be fully reused to draw power from the AC circuit to supply power to the DC bus capacitor C1. This is equivalent to completely eliminating the AC auxiliary power source in the related technology, which is conducive to further reducing the number of components in the power converter, thereby further reducing costs and PCB area.

[0077] This application does not impose specific limitations on the number of stages (or structural form) of the AC relay 230.

[0078] In some embodiments, such as Figure 4 As shown, AC relay 230 is a single-stage (or single-level) AC relay. That is, AC relay 230 includes a primary AC relay 231. Primary AC relay 231 includes a primary AC control coil and a primary controllable contact. In this embodiment, the primary AC relay 231 is a relay that closes when AC power is applied. Both ends of the primary AC control coil are connected to the AC circuit. The specific connection method depends on the structure of the AC circuit, as detailed below. One end of the primary controllable contact is connected to the input terminal of the rectifier circuit 250, and the other end is connected to the AC circuit.

[0079] In some embodiments, the AC circuit may be a single-phase AC circuit, and the primary AC relay 231 is connected to both the single-phase AC circuit and the rectifier circuit 250, so that when the primary AC relay 231 is closed, the AC power in the single-phase AC circuit is transmitted to the rectifier circuit 250.

[0080] Specifically, the primary AC relay 231 includes a primary AC control coil and a primary controllable contact. Both ends of the primary AC control coil are connected to a single-phase AC circuit to obtain AC power. The two ends of the primary controllable contact are connected to both the single-phase AC circuit and the rectifier circuit 250. When the single-phase AC circuit is energized, the primary AC control coil controls the primary controllable contact to close, so that the AC power in the single-phase AC circuit is transmitted to the rectifier circuit 250 through the closed primary controllable contact.

[0081] In other embodiments, such as Figure 5 As shown, the AC circuit can be a multi-phase AC circuit. For example, the AC circuit includes a first-phase circuit and a second-phase circuit. In some embodiments, the first-phase circuit is an L-phase circuit, and the second-phase circuit is an N-phase circuit. Based on this, the primary AC relay 231 may include a first primary AC relay 232 and a second primary AC relay 234. The input terminals of the rectifier circuit 250 include a first input terminal and a second input terminal. The first primary AC relay 232 is connected to both the first-phase circuit and the first input terminal of the rectifier circuit 250, so that when the first primary AC relay 232 is closed, it transmits the AC current in the first-phase circuit to the first input terminal of the rectifier circuit 250. The second primary AC relay 234 is connected to both the second-phase circuit and the second input terminal of the rectifier circuit 250, so that when the second primary AC relay 234 is closed, it transmits the AC current in the second-phase circuit to the second input terminal of the rectifier circuit 250.

[0082] Specifically, such as Figures 11-14 As shown, the first primary AC relay 232 includes a first primary AC control coil 233 and a first primary controllable contact K1. The two ends of the first primary AC control coil 233 are connected to the first phase circuit and the second phase circuit, respectively, to obtain AC power. The two ends of the first primary controllable contact K1 are connected to the first phase circuit and the first input terminal of the rectifier circuit 250, respectively. When the AC circuit (i.e., the first phase circuit and the second phase circuit) is energized, the first primary AC control coil 233 controls the first primary controllable contact K1 to close, so that the AC power in the first phase circuit is transmitted to the first input terminal of the rectifier circuit 250 through the closed first primary controllable contact K1. The second primary AC relay 234 includes a second primary AC control coil 235 and a second primary controllable contact K2. The two ends of the second primary AC control coil 235 are connected to the first phase circuit and the second phase circuit, respectively, to obtain AC power. The two ends of the second primary controllable contact K2 are connected to the second phase circuit and the second input terminal of the rectifier circuit 250, respectively. When the AC circuit is energized, the second primary AC control coil 235 controls the second primary controllable contact K2 to close, so that the AC current in the second phase circuit is transmitted to the second input terminal of the rectifier circuit 250 through the closed second primary controllable contact K2.

[0083] By setting the AC relay 230 as a single-stage AC relay 230, the number of components can be reduced while meeting safety constraints as much as possible, thereby helping to reduce the overall cost of the power converter 200.

[0084] Considering the safety regulations in different countries and regions, some regions may face more stringent safety regulations. Therefore, in some embodiments, the AC relay 230 can be a multi-stage AC relay. For example, as... Figure 6 As shown, the AC relay 230, in addition to the primary AC relay 231 described above, may also include a secondary AC relay 236. The secondary AC relay 236 is also a relay controlled by AC power. The secondary AC relay 236 is an AC relay connected between the primary AC relay 231 and the rectifier circuit 250. In some embodiments, the secondary AC relay 236 may also be referred to as a second-stage AC relay. The secondary AC relay 236 may include a secondary AC control coil and a secondary controllable contact. One end of the secondary controllable contact is connected to one end of the primary controllable contact, and the other end of the secondary controllable contact is connected to the input terminal of the rectifier circuit 250. By connecting the secondary AC relay 236 to the rear end of the primary AC relay 231, stricter safety regulations, contact gap, and power circuit electrical clearance requirements can be met.

[0085] This application does not specifically limit the type of the secondary AC relay 236; its specific selection is related to the safety architecture and safety requirements. For example, the secondary AC relay 236 can be an AC-energized type, a normally closed type, or other types of relays, depending on the safety architecture and the overall inverter topology design.

[0086] As mentioned above, an AC circuit may include a first-phase circuit and a second-phase circuit. Based on this, in some embodiments, such as... Figure 7 As shown, when the AC relay 230 includes a secondary AC relay 236, the secondary AC relay 236 includes a primary AC relay 237 connected to the first phase circuit and a secondary AC relay 238 connected to the second phase circuit. That is, the two ends of the primary AC relay 237 are respectively connected to the first primary AC relay 232 and the first input terminal of the rectifier circuit 250, and the two ends of the secondary AC relay 238 are respectively connected to the second primary AC relay 234 and the second input terminal of the rectifier circuit 250.

[0087] As mentioned earlier, the primary AC relay 231 is a relay that activates when AC power is available. That is, as long as the AC circuit is energized, the primary controllable contact in the primary AC relay 231 will be closed, at which point the rectifier circuit 250 will supply power to the DC bus capacitor C1 of the power converter 200. However, in some scenarios, for example, after the primary AC relay 231 and rectifier circuit 250 have been activated for a period of time following a situation where the electrical signal output from the DC power supply to the DC terminal of the power converter is less than a preset threshold, the electrical signal output from the DC power supply to the DC terminal of the power converter may then exceed or surpass the preset threshold. For example, after a period of cloudy or rainy weather or nighttime, the photovoltaic panel regains its ability to convert solar energy into DC power. Another example is when a depleted photovoltaic storage battery is recharged, or when a depleted photovoltaic storage battery is replaced with a charged one.

[0088] In this scenario, a DC power supply can continue to be used to power the DC bus capacitor C1. The next step is to control the primary AC relay 231 to promptly cut off the power supply to the DC terminal of the power converter 200 via the primary AC relay 231, thereby ensuring electrical safety.

[0089] In view of this, in some embodiments, such as Figure 5 , Figure 7 and Figures 9-10 As shown, the power converter 200 may also include a DC relay 260. As the name suggests, the DC relay 260 is a relay used in a DC circuit, or in other words, a relay controlled based on DC power. For example... Figure 11As shown, the DC relay 260 may include a DC control coil 261 and a normally closed contact K3.

[0090] The DC control coil 261 can be understood as a coil controlled by direct current, meaning that when current flows through the DC control coil 261, that current is direct current. Based on this, the DC control coil 261 can be used with... Figure 5 , Figure 7 and Figures 9-10 The second control circuit 270 shown is connected to provide DC power to the DC control coil 261, enabling the DC control coil 261 to generate an electromagnetic field that can change the state of the normally closed contact K3. Specifically, the second control circuit 270 can provide DC power to the DC control coil 261 when the electrical signal provided by the DC power supply to the power converter is greater than or equal to a preset threshold, thereby opening the normally closed contact K3. The normally closed contact K3 can be understood as a contact that is closed under normal conditions (i.e., when the DC control coil 261 is not energized). The normally closed contact K3 can be connected in series between the primary AC control coil and the AC circuit. Based on this connection, when the normally closed contact K3 is opened, the connection between the primary AC control coil and the AC circuit is broken, and no current flows through the primary AC control coil. Therefore, the primary controllable contact, which is in a closed state, can be switched to an open state. In other words, when the electrical signal at the DC terminal of the power converter is greater than or equal to a preset threshold (i.e., when the electrical signal provided by the DC power supply to the DC terminal of the power converter is greater than or equal to the preset threshold), the second control circuit 270 provides DC power to the DC control coil 261 to disconnect the normally closed contact K3, thereby disconnecting the primary controllable contact (i.e., disconnecting the primary AC relay 231).

[0091] The second control circuit 270 can not only control the state of the normally closed contact K3, but also control the state of the primary controllable contact by controlling the state of the normally closed contact K3. Based on this, in some embodiments, the second control circuit 270 can also be called the control circuit of the contact switch.

[0092] The embodiments of this application do not impose specific limitations on the second control circuit 270, as long as it can provide DC power to the DC control coil 261 when the DC power supply is available.

[0093] For example, the second control circuit 270 can be a controller capable of sensing whether a DC power supply is providing power. As an example, this controller can be connected to a DC power supply to sense whether the DC power supply is energized. When the DC power supply is energized, the second control circuit 270 is powered, thereby controlling the supply of power to the DC control coil 261. When the DC power supply is de-energized, the second control circuit 270 is de-energized, therefore, there is no power in the DC control coil 261. This application does not specifically limit the type of the second control circuit 270; for example, the second control circuit 270 can be an ARM, DSP, FPGA, etc., and the specific control method depends on the control logic and requirements.

[0094] In some embodiments, such as Figure 7 and Figures 9-10 As shown, the second control circuit 270 can be powered by the power supply circuit 280. In some cases, the power supply circuit 280 may be coupled to AC; therefore, the power supply circuit 280 can be an isolated power supply circuit or a high-impedance power supply circuit. An isolated power supply circuit can be, for example, a magnetically isolated power supply circuit, a capacitively isolated power supply circuit, or an optically isolated power supply circuit. By setting the power supply circuit 280 as an isolated power supply circuit or a high-impedance power supply circuit, the safety clearance requirements under different safety regulations can be met.

[0095] As mentioned earlier, when the AC circuit is a multi-phase AC circuit, the primary AC relay 231 may include a first primary AC relay 232 and a second primary AC relay 234. Therefore, how to configure the DC relay 260 becomes a problem that urgently needs to be solved.

[0096] In one implementation, the first primary AC relay 232 and the second primary AC relay 234 can each use different DC relays 260. That is, the DC relay 260 includes both a first DC relay 260 and a second DC relay 260. The first DC relay 260 controls the state of the first primary controllable contact K1 of the first primary AC relay 232, and the second DC relay 260 controls the state of the second primary controllable contact K2 of the second primary AC relay 234. The first DC relay 260 includes a first DC control coil 261 and a first normally closed contact K3. The second DC relay 260 includes a second DC control coil 261 and a second normally closed contact K3.

[0097] Specifically, one end of the first primary AC control coil 233 is connected to the first phase circuit in the AC circuit, and the other end of the first primary AC control coil 233 is connected to the second phase circuit in the AC circuit through the first normally closed contact K3 in the first DC relay 260. One end of the first primary controllable contact K1 is connected to the first phase circuit, and the other end of the first primary controllable contact K1 is connected to the first input terminal of the rectifier circuit 250. One end of the second primary AC control coil 235 is connected to the first phase circuit in the AC circuit, and the other end of the second primary AC control coil 235 is connected to the second phase circuit in the AC circuit through the second normally closed contact K3 in the second DC relay 260. One end of the second primary controllable contact K2 is connected to the second phase circuit, and the other end of the second primary controllable contact K2 is connected to the second input terminal of the rectifier circuit 250.

[0098] This configuration allows the normally closed contacts K3 of different DC relays 260 to control the energizing states of the first primary AC control coil 233 and the second primary AC control coil 235. When it is necessary to turn off the first primary controllable contact K1 and the second primary controllable contact K2, the second control circuit 270 controls DC power to supply power to the first and second DC control coils 261, causing the normally closed contacts K3 and K2 to open. This de-energizes the first primary AC control coil 233 and the second primary AC control coil 235, thus opening the normally closed primary controllable contacts K1 and K2. This configuration also allows disconnection of the AC circuit from the DC terminal of the power converter 200 when DC power is available.

[0099] As another implementation method, such as Figure 5 and Figure 7 As shown, the first primary AC relay 232 and the second primary AC relay 234 share the same DC relay 260. That is, the DC relay 260 is used to simultaneously control the state of the first primary controllable contact K1 of the first primary AC relay 232 and the state of the second primary controllable contact K2 of the second primary AC relay 234.

[0100] Specifically, such as Figures 11-14As shown, one end of the first primary AC control coil 233 is connected to the first phase circuit in the AC circuit, and the other end of the first primary AC control coil 233 is connected to the second phase circuit in the AC circuit through the normally closed contact K3 in the DC relay 260. One end of the first primary controllable contact K1 is connected to the first input terminal of the rectifier circuit 250, and the other end of the first primary controllable contact K1 is connected to the first phase circuit. One end of the second primary AC control coil 235 is connected to the first phase circuit in the AC circuit, and the other end of the second primary AC control coil 235 is connected to the second phase circuit in the AC circuit through the normally closed contact K3 in the DC relay 260. One end of the second primary controllable contact K2 is connected to the second input terminal of the rectifier circuit 250, and the other end of the second primary controllable contact K2 is connected to the second phase circuit. Optionally, the normally closed contact K3 can be connected to the second phase circuit in the AC circuit through a resistor R21.

[0101] This configuration allows the normally closed contact K3 of the same DC relay 260 to control the energizing state of the first primary AC control coil 233 and the second primary AC control coil 235. When it is necessary to turn off the first primary controllable contact K1 and the second primary controllable contact K2, the second control circuit 270 controls the DC power supply to the DC control coil 261 in the DC relay 260, causing the normally closed contact K3 to open. This de-energizes the first primary AC control coil 233 and the second primary AC control coil 235, thus opening the previously closed first primary controllable contact K1 and the second primary controllable contact K2. This configuration not only disconnects the AC circuit from the DC terminal of the power converter 200 when the DC power supply is available, but also further reduces the number of components, thereby reducing costs and saving PCB layout space.

[0102] Considering the large capacitance of the DC bus capacitor C1 in the power converter 200, if the DC bus capacitor C1 is directly charged at the moment the AC relay 230 (such as the primary AC relay 231 and / or the secondary AC relay 236) is energized, the large instantaneous current may damage the AC relay 230 due to the low impedance of the charging circuit. How can this problem be avoided?

[0103] As one possible implementation, such as Figures 8-10As shown, a soft-start circuit 290 can be used to avoid damage caused by the instantaneous large current charging the DC bus capacitor C1 when the AC relay 230 is energized. That is, the power converter 200 may also include a soft-start circuit 290 connected to the AC relay 230. This application embodiment does not specifically limit the connection method between the AC relay 230 and the soft-start circuit 290. For example, the soft-start circuit 290 can be connected in parallel with the AC relay 230. Alternatively, the soft-start circuit 290 can be connected in series with the AC relay 230.

[0104] This application does not specifically limit the structure of the soft-start circuit 290 in the embodiments. As an example, such as Figure 13 and Figure 14 As shown, the slow-start circuit 290 may include a slow-start relay K6 and a slow-start resistor R22. The working principle of the slow-start circuit 290 is as follows: First, the slow-start relay K6 is closed, and the DC bus capacitor C1 is powered through the slow-start circuit 290. When the voltage of the DC bus capacitor C1 is charged to near the rated voltage, the AC relay 230 is closed, and then the slow-start relay K6 is opened. This can reduce the inrush current when the AC relay 230 is closed, so as to avoid the risk of failure of the AC relay 230.

[0105] As mentioned above, AC relay 230 may include only primary AC relay 231. Alternatively, AC relay 230 may include primary AC relay 231 and secondary AC relay 236. Furthermore, when the AC circuit is a multi-phase AC circuit, there may be multiple primary AC relay 231 or secondary AC relay 236. In other words, there are many types and configurations of AC relay 230. Therefore, this application embodiment does not specifically limit which AC relay 230 the soft-start circuit 290 is connected to.

[0106] As an example, such as Figure 9 and Figure 10 As shown, the soft-start circuit 290 is connected to the primary AC relay 231. For example, the first primary AC relay 232 and the second primary AC relay 234 can be connected to different soft-start circuits 290 respectively. Figure 9 and Figure 10 (Not shown). For example, the first primary AC relay 232 and the second primary AC relay 234 can be connected to the same soft-start circuit 290 (e.g., Figure 10 As shown in the diagram. For example, one of the first primary AC relay 232 and the second primary AC relay 234 is connected to the soft-start circuit 290, while the other is not connected to the soft-start circuit 290 (as shown in the diagram). Figure 9 (As shown).

[0107] As yet another example, such as Figure 13 and Figure 14As shown, the soft-start circuit 290 is connected to the secondary AC relay 236. For example, the primary AC relay 237 and the secondary AC relay 238 can be connected to different soft-start circuits 290 respectively. Figure 12 and Figure 13 (Not shown). For example, the primary AC relay 237 and the secondary AC relay 238 can be connected to the same soft-start circuit 290 (…). Figure 13 and Figure 14 (Not shown). For example, one of the primary AC relay 237 and the secondary AC relay 238 is connected to the soft-start circuit 290, while the other is not connected to the soft-start circuit 290 (e.g., ...). Figure 13 (As shown). For example, the primary AC relay 237 is connected to the soft-start circuit 290, and the secondary AC relay 238 does not exist (as shown). Figure 14 (As shown).

[0108] Regarding the power converter 200 mentioned earlier, when the DC bus capacitor C1 in the power converter 200 is powered by the electricity flowing through the AC relay 230, the auxiliary power supply circuit 240 and the first control circuit 241 can be continuously powered. Based on this, the first control circuit 241 can maintain its ability to monitor the power converter 200. In some scenarios, the first control circuit 241 may detect an anomaly in the power converter 200. If an anomaly occurs, continuing to use AC power to charge the DC bus capacitor may pose a safety hazard to the power converter or cause it to shut down directly.

[0109] To address the aforementioned issues, as one implementation, the power converter 200 can respond to a situation where it draws power from the AC circuit via the AC relay 230 to supply power to the DC bus capacitor C1, and an abnormality occurs in the power converter 200. In this case, the first control circuit 241 sends an abnormality alert signal to the central control unit and controls the AC relay 230 to shut down. The central control unit can be understood as a control system for facilitating user operation or monitoring of the power converter. The central control unit may be equipped with a display. When the first control circuit 241 sends an abnormality alert signal to the central control unit, the central control unit can display the alert signal, allowing the user to be aware of the power converter malfunction and to troubleshoot the problem as quickly as possible.

[0110] As another implementation method, for example Figure 6 and Figure 7 With respect to the AC relay 230 shown, the power converter 200 can respond to the fact that it draws power from the AC circuit through the AC relay 230 to supply power to the DC bus capacitor C1 and the power converter 200 malfunctions, by using the first control circuit 241 to control the secondary AC relay 236 to turn off and control the primary AC relay 231 to close, so as to draw power from the AC circuit through the primary AC relay 231 to supply power to the DC bus capacitor C1.

[0111] This application does not impose specific limitations on the circuit structure of the auxiliary power supply circuit 240. As an example, the circuit structure of the auxiliary power supply circuit 240 is similar to that of the DC-DC114 described above.

[0112] For example, such as Figures 11-14 As shown, the auxiliary power supply circuit 240 may include an isolation transformer T1. The primary side of T1 includes a primary winding, the two ends of which are connected to the output terminal of the rectifier circuit 250 to obtain the input voltage from the rectifier circuit 250. The secondary side of T1 includes a secondary winding, a rectifier diode D4, and an output capacitor C2. The secondary side has an output terminal, which is used to provide an output voltage V to the first control circuit 241 of the power converter 200. out .

[0113] The auxiliary power supply circuit 240 may further include a controllable switch Q1 and a voltage regulation circuit connected to the primary side. The controllable switch Q1 is used to control the on / off state of the primary side. The two ends of the controllable switch Q1 are connected to the primary winding and the other end of the DC bus capacitor C1, respectively. Optionally, the controllable switch can be connected to the other end of the DC bus capacitor C1 via a resistor R2. The voltage regulation circuit is connected to the output terminal of the secondary side and the control terminal of the controllable switch Q1, respectively. The voltage regulation circuit can be used to monitor the output voltage V. out And based on the detected output voltage V out Controlling the on and off times of the controllable switch Q1 to make the output voltage V out The voltage is stabilized at a preset value. For example, the voltage regulation circuit may include a PWM controller 242, a reference voltage supply circuit, and so on.

[0114] The PWM controller 242 can be connected to one end of the DC bus capacitor C1, the output terminal of the optocoupler 243, and the control terminal of the controllable switch Q1 to control the output voltage V. out The PWM controller 242 controls the on and off times of the controllable switch Q1. In some embodiments, the PWM controller 242 can be connected to one end of the input capacitor DC bus capacitor C1 via resistor R1.

[0115] The reference voltage supply circuit consists of resistors R3, R4, and R5, as well as a voltage reference V. REF Together they form a voltage reference V. REF The value is determined by V out The values ​​of resistors R4 and R5 are determined together.

[0116] The input terminals of the optocoupler 243 are respectively connected to the voltage reference V REF Connected to R3, the output of optocoupler 243 is connected to PWM controller 242 to output a feedback signal to PWM controller 242.

[0117] It should be noted that, Figures 11-14 The power converter described is an exemplary structure, provided only to facilitate understanding of the solution presented in this application, and should not be construed as limiting the scope of this application. This application can also reasonably recombine the solutions described above, and such recombination should also be included within the protection scope of this application. Furthermore, for ease of understanding, Figures 11-14 The focus is on showcasing the power supply circuit of the auxiliary circuit in the power converter; therefore, in Figures 11-14 In the illustrated embodiment, the structure of part of the main power circuit is omitted, for example, Figure 11 The DC-DC converter circuit and inverter circuit in the main power circuit are omitted. Figures 12-14 The DC-DC converter circuit in the main power circuit is omitted, which does not mean that... Figures 11-14 The power converter shown does not have a main power circuit; its structure, which includes the main power circuit, should be referenced from [reference needed]. Figures 2-10 As shown.

[0118] In addition, this application embodiment also provides a photovoltaic-storage-charging system. The photovoltaic-storage-charging system may include a DC power supply and a power converter 200. The DC power supply includes a photovoltaic panel and / or a photovoltaic storage battery, used to provide DC power. The power converter 200 is the power converter 200 described above, connected to both the DC power supply and an AC circuit, and used to perform power conversion between the DC power supply and the AC circuit.

[0119] In the embodiments provided in this disclosure, it should be understood that the disclosed systems and apparatuses can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, or indirect coupling or communication connection between devices or units, and may be electrical, mechanical, or other forms.

[0120] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0121] In addition, the functional units in the various embodiments of this disclosure can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0122] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A power converter, characterized in that, include: The circuit includes a DC bus capacitor, an auxiliary power supply circuit, an inverter circuit, an AC relay, and a first control circuit, among which: One end of the DC bus capacitor is connected to the DC terminal of the power converter, which is used to connect to a DC power supply. The other end of the DC bus capacitor is connected to the DC terminal of the inverter circuit. The AC terminal of the inverter circuit is connected to one end of the AC relay, which is used to connect to an AC circuit. The input terminal of the auxiliary power supply circuit is connected to the DC bus capacitor, and the output terminal of the auxiliary power supply circuit is connected to the power supply terminal of the first control circuit. The auxiliary power supply circuit uses the DC power of the DC bus capacitor to provide the target DC power to the first control circuit. In response to the electrical signal at the DC terminal of the power converter being less than a preset threshold and the AC circuit being energized, the AC relay is closed to draw power from the AC circuit through the AC relay to supply power to the DC bus capacitor.

2. The power converter according to claim 1, characterized in that, Also includes: A rectifier circuit is provided, wherein the input terminal of the rectifier circuit is connected to one end of the AC relay, and the output terminal of the rectifier circuit is connected to one end of the DC bus capacitor. In response to the closure of the AC relay, the rectifier circuit converts the AC power obtained by the AC relay from the AC circuit into DC power to supply power to the DC bus capacitor.

3. The power converter according to claim 2, characterized in that, The rectifier circuit is a rectifier bridge.

4. The power converter according to claim 2, characterized in that, The rectifier circuit is formed by the body diode of the switching transistor in the inverter circuit.

5. The power converter according to claim 2, characterized in that, The AC relay includes a primary AC relay, which includes a primary AC control coil and a primary controllable contact. Both ends of the primary AC control coil are connected to the AC circuit. One end of the primary controllable contact is connected to the input terminal of the rectifier circuit, and the other end is used to connect to the AC circuit.

6. The power converter according to claim 5, characterized in that, Also includes: A DC relay includes a DC control coil and a normally closed contact. The DC control coil is connected to a second control circuit. The normally closed contact is connected in series between the primary AC control coil and the AC circuit. The second control circuit is used to provide DC power to the DC control coil when the electrical signal at the DC terminal of the power converter is greater than or equal to a preset threshold, so as to disconnect the normally closed contact and the primary controllable contact.

7. The power converter according to claim 6, characterized in that, The primary AC relay includes: The first primary AC relay includes a first primary AC control coil and a first primary controllable contact. One end of the first primary AC control coil is connected to the first phase circuit in the AC circuit, and the other end of the first primary AC control coil is connected to the second phase circuit in the AC circuit through the normally closed contact. One end of the first primary controllable contact is connected to the input terminal of the rectifier circuit, and the other end of the first primary controllable contact is connected to the first phase circuit. The second primary AC relay includes a second primary AC control coil and a second primary controllable contact. One end of the second primary AC control coil is connected to the first phase circuit in the AC circuit, and the other end of the second primary AC control coil is connected to the second phase circuit in the AC circuit through the normally closed contact. One end of the second primary controllable contact is connected to the input terminal of the rectifier circuit, and the other end of the second primary controllable contact is connected to the second phase circuit.

8. The power converter according to claim 5, characterized in that, The AC relay further includes a secondary AC relay, wherein one end of the primary controllable contact is connected to the input terminal of the rectifier circuit through the secondary controllable contact of the secondary AC relay.

9. The power converter according to claim 1, characterized in that, Also includes: The soft-start circuit is connected to the AC relay.

10. The power converter according to claim 9, characterized in that, The soft-start circuit includes: A slow-start relay and a slow-start resistor are connected in series.

11. The power converter according to claim 1, characterized in that, In response to the AC circuit drawing power from the AC circuit to supply power to the DC bus capacitor via the AC relay and the power converter malfunctioning, the first control circuit sends an abnormality warning signal to the central control unit and controls the AC relay to turn off.

12. The power converter according to claim 8, characterized in that, In response to a power converter malfunction and the AC circuit draws power from the AC circuit to supply power to the DC bus capacitor, the first control circuit controls the secondary AC relay to turn off and controls the primary AC relay to close, so as to draw power from the AC circuit using the primary AC relay to supply power to the DC bus capacitor.

13. A photovoltaic energy storage and charging system, characterized in that, include: DC power supply, including photovoltaic panels and / or photovoltaic storage batteries, for providing DC power; The power converter as described in any one of claims 1-12 is connected to the DC power supply and the AC circuit respectively, and the power converter is used to perform power conversion between the DC power supply and the AC circuit.

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