Power converter, relay and optical storage system

Abstract

The invention provides a power converter, a relay and an optical storage system, and belongs to the technical field of circuits. In the scheme provided by the invention, the relay comprises the first electromagnet and the second electromagnet, and the armature is arranged between the first electromagnet and the second electromagnet. Based on the design, when the relay is controlled to be disconnected, the controller can control the driving circuit to supply power to the second electromagnet and cut off the power of the first electromagnet. Therefore, the attraction force generated by the second electromagnet can accelerate the movement of the armature, so that the movable contact and the static contact can be quickly disconnected. According to the scheme, the breaking speed of the relay can be increased without increasing the elastic force of the reverse spring (or the reset reed), so that the pull-in voltage and the operation power consumption of the relay can be effectively prevented from being increased, and the complexity of thermal design of the relay is prevented from being increased.

Description

Technical Field

[0001] The present application relates to the field of circuit technology, and in particular to a power converter, a relay and a photovoltaic storage system. Background Art

[0002] The photovoltaic storage system generally includes an energy storage battery and a power converter, and the power converter can be an energy storage converter (power conversion system, PCS). The DC end of the power converter is connected to the energy storage battery, and the AC end is connected to the power grid. The power converter can convert the direct current (DC) provided by the energy storage battery into alternating current (AC), and output the AC to the power grid. In addition, the power converter can also convert the AC power of the power grid into DC power and charge the energy storage battery.

[0003] A power converter usually includes a power conversion circuit, a relay, and a controller. The AC end of the power conversion circuit is connected to the power grid through a relay. Under normal circumstances, the relay is in the energized state, and the AC power output by the power conversion circuit can be transmitted to the power grid. In a fault scenario, the controller can disconnect the relay, thereby cutting off the path between the power conversion circuit and the power grid.

[0004] In order to ensure that the relay can be disconnected quickly in a fault scenario, it is usually necessary to increase the elastic force of the restoring reed in the relay. However, increasing the elastic force of the restoring reed will increase the pull-in voltage required for the relay to be pulled in, thereby increasing the operating power consumption of the relay. Summary of the invention

[0005] The present application provides a power converter, a relay and a photovoltaic storage system, which can realize rapid disconnection of the relay without increasing the operating power consumption of the relay.

[0006] In the first aspect, a power converter is provided, which includes: a power conversion circuit, a relay, a drive circuit and a controller. The relay includes: a moving contact, a static contact, a first electromagnet, a second electromagnet, and an armature located between the first electromagnet and the second electromagnet. The power conversion circuit is used to convert direct current from a photovoltaic component or an energy storage battery into alternating current for output, one of the moving contact and the static contact is connected to the AC end of the power conversion circuit, and the other contact is used to connect to the power grid. The armature is connected to the moving contact to ensure that the movement of the armature can drive the moving contact to move synchronously. The controller is used to: control the drive circuit to power the first electromagnet, the suction force generated by the first electromagnet on the armature causes the armature to drive the moving contact to move, and the moving contact is attracted to the static contact to close the relay; control the drive circuit to power the second electromagnet, and cut off the power to the first electromagnet, the suction force generated by the second electromagnet on the armature causes the armature to drive the moving contact to move, and the moving contact is disconnected from the static contact to disconnect the relay.

[0007] When controlling the relay to disconnect, since the controller can control the driving circuit to power the second electromagnet and disconnect the first electromagnet, the suction force generated by the second electromagnet can accelerate the movement of the armature, so that the moving contact and the static contact can be quickly disconnected. Since the solution provided by the present application can speed up the disconnection speed of the relay without increasing the elastic force of the restoring spring (or counter spring) in the relay, it can effectively avoid increasing the pull-in voltage and operating power consumption of the relay, and avoid increasing the complexity of the thermal design of the relay.

[0008] Optionally, the voltage provided by the driving circuit to the second electromagnet can be higher than the voltage provided by the driving circuit to the first electromagnet. By providing a higher power supply voltage (for example, much higher than the power supply voltage of the first electromagnet) to the second electromagnet, the second electromagnet can quickly generate a larger instantaneous magnetic field under the action of the higher power supply voltage, thereby effectively accelerating the movement of the armature and realizing the rapid disconnection of the moving contact and the static contact.

[0009] Optionally, the drive circuit may include: a first power supply, a second power supply, a first switch, and a second switch. The first electromagnet and the first switch connected in series are used to be connected to both ends of the first power supply, and the second electromagnet and the second switch connected in series are used to be connected to both ends of the second power supply. The controller is used to control the on-off of the first switch so that the first power supply supplies power to or cuts off power to the first electromagnet. The controller is also used to control the on-off of the second switch so that the second power supply supplies power to or cuts off power to the second electromagnet.

[0010] It is understandable that when the controller controls the first switch to be turned on, the first power supply can supply power to the first electromagnet. When the controller controls the first switch to be turned off and controls the second switch to be turned on, the second power supply can supply power to the second electromagnet, and the first electromagnet is powered off. Based on the above structure of the drive circuit, independent power supply to the first electromagnet and the second electromagnet can be achieved, and flexible control of the power supply and power-off state of the two electromagnets can be achieved, thereby effectively improving the flexibility of controlling the relay.

[0011] Optionally, the drive circuit may further include: a capacitor and a third switch. The capacitor and the third switch connected in series are used to be connected to both ends of the second power supply, and one end of the second electromagnet connected in series with the second switch is connected to one end of the second power supply through the third switch. The controller may also be used to: when the relay is closed, control the second switch to be disconnected, and control the third switch to be closed, so that the second power supply charges the capacitor, and after the capacitor is charged, control the third switch to be disconnected. Furthermore, the controller may also be used to: control the second switch to be closed, so that the capacitor supplies power to the second electromagnet.

[0012] Since the capacitor supplies power to the second electromagnet after the second switch is closed, the second electromagnet and the second switch only need to withstand the current converted from the amount of electricity on the capacitor. Compared with the solution of directly supplying power from the second power supply, supplying power through the capacitor can prevent the second electromagnet and the second switch from bearing continuous large current. As a result, the requirements for the current resistance characteristics and temperature rise specifications of the second electromagnet and the second switch can be effectively reduced, thereby effectively reducing the cost and design complexity of the power converter.

[0013] Optionally, the drive circuit may further include: a fourth switch. Furthermore, the first switch, the second switch and the fourth switch in the drive circuit may all be N-type transistors. Wherein, the gate of the fourth switch and the gate of the second switch are both connected to the positive electrode of the first power supply, the first electrode of the fourth switch is connected to the gate of the second switch, and the second electrode of the fourth switch is connected to the negative electrode of the first power supply. The controller may be used to provide a switch control signal to the gate of the first switch and the gate of the fourth switch to control the first switch and the fourth switch to be turned on or turned off. That is, the controller may control the first switch and the fourth switch to act synchronously, i.e., to be turned on at the same time or turned off at the same time, through one switch control signal.

[0014] When the switch control signal provided by the controller controls the first switch and the fourth switch to be turned on, the first power supply can supply power to the first electromagnet. Since the fourth switch is also turned on, the turned-on fourth switch makes the gate of the second switch connected to the negative pole of the first power supply, so the second switch remains in the off state, and the second electromagnet is not powered on. When the switch control signal provided by the controller controls the first switch and the fourth switch to be turned off, the first electromagnet is powered off. And, since the fourth switch is turned off, and the gate of the second switch is connected to the positive pole of the first power supply, the second switch can be turned on, and the second power supply can then supply power to the second electromagnet. It can be seen from this that by setting the fourth switch, the controller can realize the control of the on-off state of the first switch and the second switch through a switch control signal. And, it can be ensured that the on-off state of the first switch and the second switch is complementary, thereby ensuring that when the first electromagnet is powered on, the second electromagnet is powered off, and when the second electromagnet is powered on, the first electromagnet is powered off.

[0015] Optionally, the first electromagnet may include: a first magnetic core, and a first coil wound on the first magnetic core. The second electromagnet may include: a second magnetic core, and a second coil wound on the second magnetic core. The saturation magnetic flux density of the second magnetic core is greater than the saturation magnetic flux density of the first magnetic core.

[0016] Since the saturation magnetic flux density of the second magnetic core is relatively large, it can be ensured that after providing a higher power supply voltage to the second electromagnet, the second electromagnet can generate a larger instantaneous magnetic field. Accordingly, the second electromagnet can generate a larger suction force on the armature to ensure that the armature can move quickly, thereby enabling the moving contact and the static contact of the relay to be quickly disconnected.

[0017] Optionally, the relay may further include a moving reed, one end of which is connected to the armature, and the other end of which is connected to the moving contact. Based on this connection relationship, it can be ensured that when the armature moves under the suction of the electromagnet, the moving contact can be driven to move, thereby closing or disconnecting the moving contact and the static contact.

[0018] Optionally, the controller can be used to: control the drive circuit to provide a first voltage to the first electromagnet, so that the suction force generated by the first electromagnet on the armature causes the armature to drive the movable contact to move, so as to attract the movable contact and the stationary contact; and, after the movable contact and the stationary contact are attracted, control the drive circuit to provide a second voltage to the first electromagnet, so that the suction force generated by the first electromagnet on the armature keeps the movable contact and the stationary contact in an attracted state. The second voltage is less than the first voltage.

[0019] In the initial state, since there is a certain distance between the armature and the first electromagnet, the drive circuit needs to first provide a relatively high first voltage to the first electromagnet so that the suction force generated by the first electromagnet can move the armature in the direction close to the first electromagnet, thereby closing the moving contact and the static contact. After the moving contact and the static contact are closed, since the distance between the armature and the first electromagnet is small (for example, the two are in direct contact), the drive circuit provides a relatively low second voltage, so that the moving contact and the static contact continue to remain in the closed state. Since the above-mentioned second voltage is relatively low, the operating power consumption of the relay can be effectively reduced.

[0020] In the second aspect, a relay is provided, which can be applied to the power converter provided in the first aspect, or can be applied to other equipment that needs to achieve rapid disconnection. The relay includes: a moving contact, a static contact, a first electromagnet, a second electromagnet, and an armature located between the first electromagnet and the second electromagnet. After the first electromagnet is powered, the first electromagnet is used to generate suction on the armature, so that the armature drives the moving contact to move, so as to attract the moving contact and the static contact, thereby closing the relay. After the second electromagnet is powered and the first electromagnet is powered off, the second electromagnet is used to generate suction on the armature, so that the armature drives the moving contact to move, so as to disconnect the moving contact and the static contact, thereby disconnecting the relay.

[0021] The relay provided in the embodiment of the present application includes a first electromagnet and a second electromagnet, and the armature is arranged between the first electromagnet and the second electromagnet. Based on this design, when the control relay is disconnected, the second electromagnet can be powered and the first electromagnet can be powered off. As a result, the suction force generated by the second electromagnet can accelerate the movement of the armature, so that the moving contact and the static contact can be quickly disconnected.

[0022] In a third aspect, a photovoltaic storage system is provided, the photovoltaic storage system comprising: an energy storage battery, and a power converter as provided in the first aspect above. The energy storage battery is used to provide direct current to the power converter, the power converter is used to convert direct current into alternating current and output the alternating current to a power grid, and the power converter is also used to convert the alternating current provided by the power grid into direct current to charge the energy storage battery.

[0023] In summary, the present application provides a power converter, a relay and a photoelectric storage system. In the solution provided in the present application, the relay includes a first electromagnet and a second electromagnet, and the armature is arranged between the first electromagnet and the second electromagnet. Based on this design, when the relay is controlled to disconnect, the controller can control the drive circuit to power the second electromagnet and cut off the power to the first electromagnet. As a result, the suction force generated by the second electromagnet can accelerate the movement of the armature, so that the moving contact and the static contact can be quickly disconnected. Since the above scheme can speed up the disconnection speed of the relay without increasing the elastic force of the recovery spring (or counter spring) in the relay, it can effectively avoid increasing the pull-in voltage and operating power consumption of the relay, and avoid increasing the complexity of the thermal design of the relay. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a structural schematic diagram of a photovoltaic storage system provided in an embodiment of the present application;

[0025] Figure 2 is a structural schematic diagram of another optical storage system provided in an embodiment of the present application;

[0026] Figure 3 is a schematic diagram of the structure of a power converter provided in an embodiment of the present application;

[0027] Figure 4 is a schematic diagram of the structure of another power converter provided in an embodiment of the present application;

[0028] Figure 5 This is a schematic diagram of the structure of a relay in different states provided by an embodiment of the present application;

[0029] Figure 6 It is a structural schematic diagram of another power converter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0030] The power converter, relay and photovoltaic storage system provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0031] Figure 1 Schematic diagram of a structure of a photovoltaic storage system provided in an embodiment of the present application. Figure 1As shown, the photo-storage system may include a photovoltaic (PV) panel, an energy storage battery and a power converter. The photovoltaic panel and the energy storage battery are connected to different power converters 01. Among them, the power converter 01 connected to the photovoltaic panel may be an inverter, and the power converter 01 connected to the energy storage battery may be a PCS. The photovoltaic panel is used to provide direct current, and the inverter is used to convert the direct current into alternating current, and output it to a power grid or a load. The energy storage battery is used to provide direct current, and the PCS is used to convert the direct current into alternating current, and output it to a power grid or a load. In addition, the PCS can also charge the energy storage battery after converting the alternating current provided by the power grid or the inverter into direct current. That is, the PCS can achieve bidirectional energy conversion.

[0032] Continue to refer Figure 1 The photovoltaic storage system may include multiple photovoltaic panels, which are connected in series to the DC end of the inverter, and the AC end of the inverter is connected to the grid or load. The photovoltaic storage system may include multiple energy storage batteries, which are connected in series to the DC end of the PCS, and the AC end of the PCS is connected to the grid or load.

[0033] Figure 2 is a schematic diagram of the structure of another optical storage system provided in an embodiment of the present application, and Figure 2 The power converter 01 is taken as an inverter for example. Figure 2 As shown, the power converter 01 includes a power conversion circuit 011 and a relay 012. The power conversion circuit 011 is used to receive the direct current provided by the photovoltaic panel 00, and is used to convert the direct current into alternating current. The relay 012 is connected between the AC end of the power conversion circuit 011 and the power grid, for example, between the AC end of the power conversion circuit 011 and the input end of the transformer 02. The relay 012 is used to control the on-off between the AC end of the power conversion circuit 011 and the power grid. The relay 012 is also called a grid-connected relay.

[0034] It is understandable that the power converter 01 can be a single-phase or multi-phase power converter. The AC end of the power conversion circuit 011 of the power converter 01 is connected to at least one phase line in a one-to-one correspondence, and at least one relay 012 can be connected in series on each phase line. Figure 1 The power converter 01 is a three-phase power converter, and the AC end of the power conversion circuit 011 is connected to the three phase lines one by one, and each phase line is connected to a relay 012. It can also be understood that in order to improve reliability, each phase line is usually connected in series with multiple relays 012, for example, two relays 012 can be connected in series.

[0035] In a fault scenario, the power conversion circuit 011 will output a large fault current. For example, when the negative pole PV- of the power line of the photovoltaic panel 00 is short-circuited to the ground, since the neutral line (N line) of the transformer 02 is grounded, Figure 1 As shown by the solid arrow in , the body diode of the switch tube (such as the switch tube Q6) in the power conversion circuit 011, the relay 012 and the transformer 02 will form a fault current (also called short-circuit current) loop. At this time, the moving contact and the static contact in the relay 012 need to be disconnected in time to prevent the fault current from damaging the device.

[0036] It can also be understood that the current that the relay 012 can interrupt is limited. That is, if the fault current is too large, the relay 012 will not be able to effectively interrupt. In an AC power grid, since the magnitude of the AC current changes periodically, the relay 012 can be disconnected when the fault current is small (for example, 0).

[0037] In addition, in some fault scenarios, the fault current may be unidirectional, that is, in one cycle of AC power, there is fault current only in half of the cycle, and no fault current in the other half of the cycle. Figure 1 In the scenario shown in FIG. 1 where the negative electrode PV- is short-circuited to the ground, the switch tube (e.g., switch tube Q6) in the power conversion circuit 011 can be controlled to be turned off. Thus, based on the turned-off switch tube and the diode D0 connected to the positive electrode PV+ of the power line of the photovoltaic panel 00, the generation of a fault current in the other direction can be avoided ( Figure 1 In the fault scenario where the fault current is unidirectional, the relay 012 can be disconnected in the half cycle without the fault current.

[0038] Based on the above analysis, it can be seen that if the fault current is large, in order to ensure that the relay 012 can be disconnected in time and effectively, the relay 012 needs to be disconnected quickly in the stage where the fault current is small, or in the half cycle when there is no fault current. Therefore, the disconnection delay of the relay 012 has a great influence on the protection effect.

[0039] Relay 012 usually includes: a moving contact, a static contact, an armature, an electromagnet and a counter spring (or a restoring spring). Among them, the armature is connected to the moving contact and the counter spring respectively. When the electromagnet is powered, the suction force generated by the electromagnet can move the armature, and the armature drives the moving contact to move, and causes the moving contact to attract the static contact, thereby causing the relay to attract. When the electromagnet is powered off, the magnetic field (i.e., suction force) generated by the electromagnet disappears, and the armature is reset under the elastic force of the counter spring, and drives the moving contact to disconnect from the static contact, thereby causing the relay to disconnect. In order to reduce the disconnection delay of relay 012 and increase the disconnection speed of relay 012, the elastic force of the counter spring or the restoring spring in relay 012 is usually increased. As a result, the elastic force of the moving contact in relay 012 when released can be increased, thereby accelerating the disconnection of the moving contact and the static contact in relay 012. However, increasing the elastic force of the counter-spring or the restoring spring will increase the pull-in voltage and operating power consumption of the relay 012 , and will also affect the overall thermal design of the relay 012 .

[0040] The above is an explanation based on the application of the power converter 01 to the photovoltaic storage system. It is understandable that the power converter 01 can also be applied to other scenarios. For example, the power converter 01 can also be applied to an energy storage system, which may not include photovoltaic panels and inverters. Alternatively, the power converter 01 can also be applied to a photovoltaic power generation system, which may not include energy storage batteries and PCS.

[0041] The embodiment of the present application provides a power converter, which can realize the rapid disconnection of the relay without increasing the pull-in voltage and operating power consumption of the relay. The power converter can be an inverter or a PCS, and can be applied to Figure 1 or Figure 2 In the optical storage system shown in the figure. Figure 3 As shown, the power converter includes: a power conversion circuit 011, a relay 012, a drive circuit 013 and a controller 014. Figure 4 and Figure 5 The relay 012 includes a moving contact 0121, a stationary contact 0122, a first electromagnet 0123, a second electromagnet 0124, and an armature 0125 located between the first electromagnet 0123 and the second electromagnet 0124. The axis of the first electromagnet 0123 and the axis of the second electromagnet 0124 can be parallel or colinear, and the first electromagnet 0123, the armature 0125 and the second electromagnet 0124 are arranged along the extension direction of the axis.

[0042] The DC end of the power conversion circuit 011 is used to connect to the photovoltaic module or the energy storage battery. The power conversion circuit 011 is used to convert the DC power from the photovoltaic module or the energy storage battery into AC power for output.

[0043] One of the moving contact 0121 and the stationary contact 0122 of the relay 012 is connected to the AC end of the power conversion circuit 011 , and the other contact is used to connect to the power grid.

[0044] The armature 0125 is connected to the moving contact 0121. The connection can be a direct connection or an indirect connection. Figure 5 The relay 012 may further include a movable spring 0126, one end of which is connected to the armature 0125, and the other end of which is connected to the movable contact 0121. That is, the armature 0125 may be connected to the movable contact 0121 through the movable spring 0126. Alternatively, the movable contact 0121 may be directly disposed on the armature 0125. Alternatively, the armature 0125 may not be in direct contact with the movable contact 0121 in the initial state (i.e., in the state where it is not subjected to the suction force of any electromagnet), and after the armature 0125 moves under the action of the suction force of the electromagnet, it may be in contact with the movable contact 0121 and drive the movable contact 0121 to move. The embodiment of the present application does not limit the linkage method between the armature 0125 and the moving contact 0121. It only needs to ensure that the armature 0125 can drive the moving contact 0121 to move when it moves, that is, there is a transmission connection relationship between the armature 0125 and the moving contact 0121.

[0045] Controller 014 is used for:

[0046] The control driving circuit 013 supplies power to the first electromagnet 0123, and the suction force generated by the first electromagnet 0123 on the armature 0125 causes the armature 0125 to drive the moving contact 0121 to move, so that the moving contact 0121 and the static contact 0122 are attracted, so that the relay 012 is attracted;

[0047] The control drive circuit 013 supplies power to the second electromagnet 0124 and cuts off the power to the first electromagnet 0123. The suction force generated by the second electromagnet 0124 on the armature 0125 causes the armature 0125 to drive the moving contact 0121 to move, disconnecting the moving contact 0121 from the static contact 0122, so that the relay 012 is disconnected.

[0048] In the embodiment of the present application, when AC power needs to be transmitted between the power conversion circuit 011 and the power grid, the controller 014 may determine that the relay 012 needs to be closed. Figure 5 , the controller 014 can control the driving circuit 013 to supply power to the first electromagnet 0123, so that the moving contact 0121 and the static contact 0122 are attracted. After the moving contact 0121 and the static contact 0122 are attracted, the alternating current output by the power conversion circuit 011 can be transmitted to the power grid through the relay 012, or the alternating current provided by the power grid can be transmitted to the power conversion circuit 011.

[0049] When the relay 012 needs to be disconnected, the controller 014 can control the drive circuit 013 to supply power to the second electromagnet 0124 and cut off the power to the first electromagnet 0123. Figure 5 As shown, the second electromagnet 0124 generates suction force on the armature 0125, and the suction force of the first electromagnet 0123 on the armature 0125 disappears. The armature 0125 can then move under the combined action of the suction force generated by the second electromagnet 0124 and the elastic force of the counterspring (or the restoring spring) connected to the armature 0125 in the relay 012, thereby disconnecting the moving contact 0121 from the static contact 0122. Since after the first electromagnet 0123 is powered off, the armature 0125 is not only subjected to the elastic force of the counterspring (or the restoring spring), but also to the suction force generated by the second electromagnet 0124, and the direction of the suction force is the direction away from the first electromagnet 0123, the armature 0125 can quickly move in the direction away from the first electromagnet 0123, thereby quickly disconnecting the moving contact 0121 from the static contact 0122.

[0050] For example, Figure 5 As shown, after the drive circuit 013 supplies power to the first electromagnet 0123, the armature 0125 can move in a direction close to the first electromagnet 0123 under the suction of the first electromagnet 0123. In addition, the armature 0125 can drive the movable contact 0121 to move in a direction close to the static contact 0122, so that the movable contact 0121 and the static contact 0122 are attracted. After the drive circuit 013 supplies power to the second electromagnet 0124 and cuts off the power to the first electromagnet 0123, the armature 0125 can move in a direction away from the first electromagnet 0123 (i.e., in a direction close to the second electromagnet 0124) under the suction of the second electromagnet 0124 and the elastic force of the counter spring (or the restoring spring sheet). In addition, the armature 0125 can drive the movable contact 0121 to move in a direction away from the static contact 0122, so that the movable contact 0121 and the static contact 0122 are disconnected.

[0051] After testing, in the scenario where the negative pole PV- of the photovoltaic panel 00 is short-circuited to the ground, the solution provided in the embodiment of the present application can reduce the disconnection delay of the relay 012 from 5 milliseconds (ms) to 2.5 ms, thereby effectively reducing the risk of high current.

[0052] It is understandable that the controller 014 can determine that the relay 012 needs to be disconnected when it detects that the current of the alternating current output by the power conversion circuit 011 is greater than the current threshold, that is, when a large fault current is detected. Alternatively, the controller 014 can determine that the relay 012 needs to be disconnected when it detects that the light intensity of the ambient light of the photovoltaic panel 00 is less than the intensity threshold (such as a period without sunlight). Alternatively, the controller 014 can determine that the relay 012 needs to be disconnected when it detects that the power converter 01 is abnormal (such as when some components are about to fail).

[0053] Based on the above analysis, it can be known that in the solution provided by the embodiment of the present application, the second electromagnet in the relay can be used as an auxiliary electromagnet to assist the counter spring (or the restoring spring) in the relay to drive the armature to move. In this way, the movement speed of the armature can be effectively increased, so that the moving contact and the static contact in the relay can be quickly disconnected. Since the above solution can speed up the disconnection speed of the relay without increasing the elastic force of the counter spring (or the restoring spring), it can effectively avoid increasing the pull-in voltage and operating power consumption of the relay, and avoid increasing the complexity of the thermal design of the relay.

[0054] Optionally, when the relay 012 needs to be closed, the controller 014 can first control the drive circuit 013 to provide a first voltage to the first electromagnet 0123, so that the suction force generated by the first electromagnet 0123 on the armature 0125 causes the armature 0125 to drive the movable contact 0121 to move, so as to close the movable contact 0121 with the static contact 0122. After the movable contact 0121 and the static contact 0122 are closed, the controller 014 can control the drive circuit 013 to provide a second voltage to the first electromagnet 0123, and the suction force generated by the first electromagnet 0123 on the armature 0125 under the action of the second voltage can keep the movable contact 0121 and the static contact 0122 in the closed state. The second voltage is less than the first voltage. For example, the first voltage can be 12 volts (V), and the second voltage can be 7V.

[0055] It can be understood that, in the initial state (also called the original state), that is, in the state where neither the first electromagnet 0123 nor the second electromagnet 0124 is powered, there is a certain distance between the armature 0125 and the first electromagnet 0123. If it is necessary to attract the moving contact 0121 and the static contact 0122, the drive circuit 013 needs to first provide a relatively high first voltage to the first electromagnet 0123 so that the first electromagnet 0123 generates a larger suction force. The larger suction force can make the armature 0125 move in a direction close to the first electromagnet 0123, thereby attracting the moving contact 0121 and the static contact 0122. Since the distance between the armature 0125 and the first electromagnet 0123 is small after the moving contact 0121 and the static contact 0122 are attracted (for example, refer to Figure 5, the armature 0125 is in contact with the first electromagnet 0123), so the drive circuit 013 provides a relatively low second voltage, which can keep the moving contact 0121 and the static contact 0122 in the attracted state. Since the second voltage is relatively low, the operating power consumption of the relay 012 can be effectively reduced.

[0056] Optionally, the voltage provided by the drive circuit 013 to the second electromagnet 0124 may be higher than the voltage provided by the drive circuit 013 to the first electromagnet 0123. It is understandable that if the drive circuit 013 can provide the first voltage and the second voltage to the first electromagnet 0123, the voltage provided by the drive circuit 013 to the second electromagnet 0124 may be higher than the first voltage. For example, the voltage provided by the drive circuit 013 to the second electromagnet 0124 may be greater than 12V, such as 50V, 100V or 150V or even higher.

[0057] By providing a higher power supply voltage (e.g., much higher than the power supply voltage of the first electromagnet 0123) to the second electromagnet 0124, the current in the coil of the second electromagnet 0124 can be increased rapidly in a short time, so that the second electromagnet 0124 can quickly generate a larger instantaneous magnetic field. In this way, the movement of the armature 0125 can be accelerated, and the moving contact 0121 and the static contact 0122 can be quickly disconnected.

[0058] Alternatively, if Figure 4 As shown, the driving circuit 013 may include: a first power supply S1, a second power supply S2, a first switch M1, and a second switch M2. The first electromagnet 0123 and the first switch M1 are connected in series, and the first electromagnet 0123 and the first switch M1 connected in series are used to connect to both ends of the first power supply S1. The second electromagnet 0124 and the second switch M2 are connected in series, and the second electromagnet 0124 and the second switch M2 connected in series are used to connect to both ends of the second power supply S2.

[0059] The controller 014 is used to control the on and off of the first switch M1, so that the first power source S1 supplies power to or cuts off the first electromagnet 0123. In addition, the controller 014 is also used to control the on and off of the second switch M2, so that the second power source S2 supplies power to or cuts off the second electromagnet 0124. It can be understood that when the controller 014 controls the first switch M1 to be turned on (also called closed), the first power source S1 can supply power to the first electromagnet 0123, so that the moving contact 0121 and the static contact 0122 are attracted. When the controller 014 controls the first switch M1 to be turned off (also called disconnected), and controls the second switch M2 to be turned on, the second power source S2 can supply power to the second electromagnet 0124, and the first electromagnet 0123 is cut off, so that the moving contact 0121 and the static contact 0122 are disconnected.

[0060] Based on the above structure of the driving circuit 013, independent power supply to the first electromagnet 0123 and the second electromagnet 0124 can be achieved, and flexible control of the power supply and power-off states of the two electromagnets can be achieved, thereby effectively improving the flexibility of controlling the relay 012.

[0061] In the embodiment of the present application, the first switch M1 and the second switch M2 may both be transistors, for example, may both be metal-oxide-semiconductor field-effect transistors (MOSFET).

[0062] As described above, for the scenario where the driving circuit 013 can provide the first voltage and the second voltage to the first electromagnet 0123. As a possible example, the first power supply S1 can be a power supply circuit with adjustable output voltage. The controller 014 can control the first power supply S1 to output the first voltage or the second voltage based on the pull-in state of the relay 012.

[0063] As another possible example, the first power supply S1 may include: a first power supply circuit and a second power supply circuit, wherein the first power supply circuit is used to provide a first voltage, and the second power supply circuit is used to provide a second voltage. The controller 014 may control the first power supply circuit or the second power supply circuit to supply power to the first electromagnet 0123 based on the pull-in state of the relay 012.

[0064] Figure 6 is a schematic diagram of the structure of another power converter provided in an embodiment of the present application, such as Figure 6 As shown, the driving circuit 013 may also include: a capacitor C0 and a third switch M3. The capacitor C0 and the third switch M3 are connected in series, and the capacitor C0 and the third switch M3 connected in series are used to connect to both ends of the second power supply S2. In addition, one end of the second electromagnet 0124 connected in series with the second switch M2 is connected to one end of the second power supply S2 through the third switch M3. For example, referring to Figure 6 One end of the second electromagnet 0124 connected in series with the second switch M2 is connected to the positive electrode of the second power supply S2 through the third switch M3.

[0065] The controller 014 can also be used to: when the relay 012 is closed, control the second switch M2 to be opened, and control the third switch M3 to be closed, so that the second power source S2 charges the capacitor C0, and after the capacitor C0 is charged, control the third switch M3 to be opened;

[0066] The controller 014 may also be used to: when the relay 012 needs to be disconnected, control the second switch M2 to be closed, so that the capacitor C0 supplies power to the second electromagnet 0124 .

[0067] In the embodiment of the present application, the controller 014 can first control the second switch M2 to turn off, and control the third switch M3 to close. At this time, the second power supply S2 can charge the capacitor C0. In addition, the controller 014 can control the third switch M3 to disconnect after the charging time of the capacitor C0 reaches a preset time. Among them, the preset time can be the time required for the capacitor C0 to be fully charged. When the relay 012 needs to be disconnected, the controller 014 can control the second switch M2 to close, and the capacitor C0 can then power the second electromagnet 0124 by discharging, so that the moving contact 0121 is disconnected from the static contact 0122.

[0068] It is understandable that in Figure 4 In the structure shown, since the second power source S2 directly supplies power to the second electromagnet 0124, after the second switch M2 is turned on, a large current will continue to flow through the second electromagnet 0124 and the second switch M2. Moreover, after the second switch M2 is turned off, the second electromagnet 0124 (equivalent to the inductor) will release energy, causing the second switch M2 to continue to withstand a high voltage. Therefore, higher requirements are placed on the current resistance characteristics and temperature rise specifications of the second electromagnet 0124 and the second switch M2. However, in Figure 6 In the structure shown, after the second switch M2 is closed, the capacitor C0 supplies power to the second electromagnet 0124, so the second electromagnet 0124 and the second switch M2 only need to withstand the current converted by the amount of electricity on the capacitor C0, and do not need to withstand a continuous large current. Therefore, the requirements for the current resistance characteristics and temperature rise specifications of the second electromagnet 0124 and the second switch M2 can be effectively reduced, thereby effectively reducing the cost and design complexity of the power converter.

[0069] Optionally, continue to refer to Figure 4 and Figure 6 The driving circuit 013 may further include: a fourth switch M4. Furthermore, the first switch M1, the second switch M2 and the fourth switch M4 may all be N-type transistors, that is, the above switches may all be NMOS.

[0070] The gate of the fourth switch M4 and the gate of the second switch M2 are both connected to the positive electrode of the first power source S1, the first electrode of the fourth switch M4 is connected to the gate of the second switch M2, and the second electrode of the fourth switch M4 is connected to the negative electrode of the first power source S1. The first electrode may be one of the source and the drain, and the second electrode may be the other of the source and the drain.

[0071] Furthermore, the controller 014 can be used to provide a switch control signal to the gate of the first switch M1 and the gate of the fourth switch M4 to control the first switch M1 and the fourth switch M4 to be turned on or turned off. That is, the controller 014 can control the first switch M1 and the fourth switch M4 to act synchronously, that is, to be turned on or turned off at the same time, through one switch control signal.

[0072] It can be understood that in the initial state, the controller 014 does not provide a switch control signal, and the first switch M1 is turned off. Since the gate of the fourth switch M4 is connected to the positive electrode of the first power supply S1, the fourth switch M4 is turned on and connects the gate of the second switch M2 to the negative electrode of the first power supply S1. At this time, the second switch M2 is turned off.

[0073] When the relay 012 needs to be energized, the switch control signal provided by the controller 014 can control both the first switch M1 and the fourth switch M4 to be turned on. At this time, the first power supply S1 can supply power to the first electromagnet 0123 through the turned-on first switch M1. Since the fourth switch M4 is also turned on, the gate of the second switch M2 is still connected to the negative electrode of the first power supply S1, so the second switch M2 continues to remain in the off state, and the second electromagnet 0124 is not powered.

[0074] When the relay 012 needs to be disconnected, the switch control signal provided by the controller 014 can control the first switch M1 and the fourth switch M4 to be turned off. At this time, the first electromagnet 0123 is powered off. Since the fourth switch M4 is turned off, and the gate of the second switch M2 is connected to the positive pole of the first power supply S1, the second switch M2 can be turned on, and the second power supply S2 can then supply power to the second electromagnet 0124 through the turned-on second switch M2. When the relay 012 needs to be closed again, the switch control signal provided by the controller 014 can control the first switch M1 and the fourth switch M4 to be turned on again. Correspondingly, the second switch M2 can be turned off.

[0075] Based on the above analysis, it can be known that by setting the fourth switch M4, the controller 014 can realize the linkage control of the on-off state of the first switch M1 and the second switch M2 through a switch control signal. In addition, it can ensure that the on-off state of the first switch M1 and the second switch M2 are complementary (also called mutually exclusive), thereby ensuring that when the first electromagnet 0123 is powered, the second electromagnet 0124 is powered off, and when the second electromagnet 0124 is powered, the first electromagnet 0123 is powered off.

[0076] Optionally, continue to refer to Figure 6, the driving circuit 013 may also include a first resistor R1 and a second resistor R2. The first resistor R1 is connected between the gate of the second switch M2 and the positive electrode of the first power supply S1, and the second resistor R2 is connected between the gate of the fourth switch M4 and the positive electrode of the first power supply S1. The first resistor R1 is used to provide a conduction voltage for the second switch M2 and limit the current. The second resistor R2 is used to provide a conduction voltage for the fourth switch M4 and limit the current.

[0077] It can also be understood that the implementation of the driving circuit 013 is only an illustration, and the driving circuit 013 can also be implemented in other ways. For example, the fourth switch M4 may not be required in the driving circuit 013. Accordingly, the gate of the second switch M2 can be directly connected to the controller 014, and the controller 014 can control the on and off states of the first switch M1 and the second switch M2 respectively through two independent switch control signals.

[0078] Alternatively, if Figure 5 As shown, the first electromagnet 0123 may include: a first magnetic core 01231, and a first coil 01232 wound on the first magnetic core 01231. The second electromagnet 0124 includes: a second magnetic core 01241, and a second coil 01242 wound on the second magnetic core 01241. The saturation magnetic flux density of the second magnetic core 01241 may be greater than the saturation magnetic flux density of the first magnetic core 01231, that is, the second magnetic core 01241 may be made of a material with a larger saturation magnetic flux density.

[0079] Saturated magnetic flux density refers to the maximum value that a magnetic material can reach under the action of a magnetic field. Since the saturated magnetic flux density of the material used in the second magnetic core 01241 is relatively large, it can be ensured that after providing a higher power supply voltage to the second electromagnet 0124, the second electromagnet 0124 can generate a larger instantaneous magnetic field. Accordingly, the second electromagnet 0124 can generate a larger suction force on the armature 0125 to ensure that the armature 0125 can move quickly, thereby enabling the moving contact 0121 and the static contact 0122 of the relay 012 to be quickly disconnected.

[0080] Optionally, the magnetic permeability of the first magnetic core 01231 may be greater than a threshold value, that is, the material of the first magnetic core 01231 may be a material with high magnetic permeability. For example, the magnetic permeability of the first magnetic core 01231 may be greater than the magnetic permeability of the second magnetic core 01241. Thus, it can be ensured that after the driving circuit 013 supplies power to the first electromagnet 0123, the first electromagnet 0123 can provide a suitable attracting magnetic field to attract the armature 0125.

[0081] In summary, an embodiment of the present application provides a power converter. The relay in the power converter includes a first electromagnet and a second electromagnet, and the armature is arranged between the first electromagnet and the second electromagnet. Based on this design, when the control is to disconnect the relay, the controller in the power converter can control the drive circuit to power the second electromagnet and disconnect the first electromagnet. As a result, the suction force generated by the second electromagnet can accelerate the movement of the armature, so that the moving contact and the static contact can be quickly disconnected. Since the above scheme can speed up the disconnection speed of the relay without increasing the elastic force of the restoring reed (or counter spring) in the relay, it can effectively avoid increasing the pull-in voltage and operating power consumption of the relay, and avoid increasing the complexity of the thermal design of the relay.

[0082] The present application also provides a relay, which can be applied to the power converter provided in the above embodiment. Figure 5 As shown, the relay includes: a moving contact 0121, a stationary contact 0122, a first electromagnet 0123, a second electromagnet 0124, and an armature 0125 located between the first electromagnet 0123 and the second electromagnet 0124.

[0083] The armature 0125 is connected to the moving contact 0121. The connection can be a direct connection or an indirect connection. Figure 5 The relay 012 may further include a moving reed 0126, and the armature 0125 may be connected to the moving contact 0121 via the moving reed 0126. Alternatively, the moving contact 0121 may be directly disposed on the armature 0125. Alternatively, the armature 0125 may not be in direct contact with the moving contact 0121 in the initial state, and after the armature 0125 moves under the suction force of the electromagnet, it may be in contact with the moving contact 0121 and drive the moving contact 0121 to move.

[0084] After the first electromagnet 0123 is powered, the first electromagnet 0123 is used to generate suction force on the armature 0125, so that the armature 0125 drives the moving contact 0121 to move, so that the moving contact 0121 and the static contact 0122 are attracted, so that the relay 012 is attracted. After the second electromagnet 0124 is powered and the first electromagnet 0123 is powered off, the second electromagnet 0124 is used to generate suction force on the armature 0125, so that the armature 0125 drives the moving contact 0121 to move, so that the moving contact 0121 and the static contact 0122 are disconnected, so that the relay 012 is disconnected.

[0085] The relay provided in the embodiment of the present application includes a first electromagnet and a second electromagnet, and the armature is arranged between the first electromagnet and the second electromagnet. Based on this design, when the control relay is disconnected, the second electromagnet can be powered and the first electromagnet can be powered off. As a result, the suction force generated by the second electromagnet can accelerate the movement of the armature, so that the moving contact and the static contact can be quickly disconnected.

[0086] It is understandable that the relay further includes an elastic connector connected to the armature, and the elastic connector may be a counterspring or a restoring spring. After the first electromagnet 0123 is powered, the suction force generated by the first electromagnet 0123 on the armature 0125 causes the armature 0125 to move in a direction close to the first electromagnet 0123, and accordingly, the elastic connector is deformed and stores elastic potential energy. After the first electromagnet 0123 is powered off, the magnetic field generated by the first electromagnet 0123 disappears, and the elastic connector can release the elastic potential energy, thereby driving the armature 0125 to move in a direction away from the first electromagnet 0123.

[0087] Optionally, the relay may further include a switch for controlling the on / off of the power supply loop of the first electromagnet, and / or a switch for controlling the on / off of the power supply loop of the second electromagnet. Figure 4 and Figure 6 , the relay may further include a first switch M1 and a second switch M2, or may further include a first switch M1, a second switch M2 and a fourth switch M4. Alternatively, in addition to the above switches, the relay may further include a capacitor C0 and a third switch M3. That is, all components except the first power supply S1 and the second power supply S2 in the drive circuit 013 may be integrated in the relay 012.

[0088] It is understandable that the relay provided in the embodiment of the present application can be applied to other devices that need to increase the disconnection speed of AC power in addition to being applied to power converters. For example, the relay can also be applied to a household photovoltaic power generation system, which includes an inverter and a backup power box, and the backup power box is connected between the inverter and the power grid. The relay provided in the embodiment of the present application can also be used in the backup power box.

[0089] In the embodiments of the present application, the terms "first", "second" and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. The term "at least one" means one or more, and "plurality" means two or more.

[0090] In the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0091] The above is only an optional implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A power converter, characterized in that: The power converter comprises: a power conversion circuit, a relay, a drive circuit and a controller; the relay comprises: a moving contact, a stationary contact, a first electromagnet, a second electromagnet, and an armature located between the first electromagnet and the second electromagnet; The power conversion circuit is used to convert direct current from the photovoltaic module or the energy storage battery into alternating current for output; One of the moving contact and the static contact is connected to the AC end of the power conversion circuit, and the other contact is used to connect to the power grid; The armature is connected to the moving contact; The controller is used to: Controlling the driving circuit to supply power to the first electromagnet, the first electromagnet generates a suction force on the armature so that the armature drives the moving contact to move, and the moving contact is attracted to the static contact, so that the relay is attracted; The driving circuit is controlled to supply power to the second electromagnet and to cut off power to the first electromagnet. The suction force generated by the second electromagnet on the armature causes the armature to drive the moving contact to move, disconnecting the moving contact from the static contact, so that the relay is disconnected.

2. The power converter according to claim 1, characterized in that: The voltage provided by the driving circuit to the second electromagnet is higher than the voltage provided by the driving circuit to the first electromagnet.

3. The power converter according to claim 1 or 2, characterized in that: The driving circuit includes: a first power supply, a second power supply, a first switch and a second switch; The first electromagnet and the first switch connected in series are used to be connected to two ends of the first power supply, and the second electromagnet and the second switch connected in series are used to be connected to two ends of the second power supply; The controller is used to control the on and off of the first switch so that the first power supply supplies power to or cuts off power to the first electromagnet; The controller is also used to control the on and off of the second switch so that the second power supply supplies power to or cuts off power to the second electromagnet.

4. The power converter according to claim 3, characterized in that: The driving circuit further includes: a capacitor and a third switch; The capacitor and the third switch connected in series are used to be connected to two ends of the second power supply; One end of the second electromagnet connected in series with the second switch is connected to one end of the second power supply through the third switch; The controller is used to control the second switch to be opened when the relay is closed, and control the third switch to be closed, so that the second power supply charges the capacitor, and control the third switch to be opened after the capacitor is charged; The controller is further used to control the second switch to close so that the capacitor supplies power to the second electromagnet.

5. The power converter according to claim 3 or 4, characterized in that: The driving circuit further includes: a fourth switch; The first switch, the second switch and the fourth switch are all N-type transistors; The gate of the fourth switch and the gate of the second switch are both connected to the positive electrode of the first power supply, the first electrode of the fourth switch is connected to the gate of the second switch, and the second electrode of the fourth switch is connected to the negative electrode of the first power supply; The controller is used to provide a switch control signal to the gate of the first switch and the gate of the fourth switch to control the first switch and the fourth switch to be turned on or turned off.

6. The power converter according to any one of claims 1 to 5, characterized in that: The first electromagnet comprises: a first magnetic core and a first coil wound on the first magnetic core; the second electromagnet comprises: a second magnetic core and a second coil wound on the second magnetic core; The saturation magnetic flux density of the second magnetic core is greater than the saturation magnetic flux density of the first magnetic core.

7. The power converter according to any one of claims 1 to 6, characterized in that: The relay further comprises a moving reed, one end of which is connected to the armature, and the other end of which is connected to the moving contact.

8. The power converter according to any one of claims 1 to 7, characterized in that: The controller is used to: Controlling the driving circuit to provide a first voltage to the first electromagnet, so that the first electromagnet generates a suction force on the armature so that the armature drives the movable contact to move, so as to attract the movable contact to the static contact; After the movable contact and the stationary contact are attracted, controlling the driving circuit to provide a second voltage to the first electromagnet, so that the first electromagnet generates a suction force on the armature to keep the movable contact and the stationary contact in an attracted state; The second voltage is smaller than the first voltage.

9. A relay, characterized in that: The relay comprises: a moving contact, a stationary contact, a first electromagnet, a second electromagnet, and an armature located between the first electromagnet and the second electromagnet; The armature is connected to the moving contact; Wherein, after the first electromagnet is powered, the first electromagnet is used to generate suction force on the armature, so that the armature drives the moving contact to move, so as to attract the moving contact and the static contact, so as to attract the relay; After the second electromagnet is powered on and the first electromagnet is powered off, the second electromagnet is used to generate suction force on the armature, so that the armature drives the moving contact to move, thereby disconnecting the moving contact from the static contact, so as to disconnect the relay.

10. A solar energy storage system, characterized in that: The photovoltaic storage system comprises: an energy storage battery, and a power converter as claimed in any one of claims 1 to 8; The energy storage battery is used to provide direct current to the power converter; The power converter is used to convert the direct current into alternating current and output the alternating current to a power grid; The power converter is also used to convert the alternating current provided by the power grid into direct current for charging the energy storage battery.

Images