Patent ID: 12224140

DETAILED DESCRIPTION

In the following description of various aspects of the disclosure, reference is made to the accompanying drawings, which form a part hereof, and in which is shown, by way of illustration, various embodiments in which aspects of the disclosure may be practiced. It is to be understood that other embodiments may be utilized and structural and functional modifications may be made, without departing from the scope of the present disclosure.

To reduce power consumption in electrical/power circuits, a latching relay (e.g., a relay that may maintain either ON or OFF contact configuration/position indefinitely without power applied to the coil) may be used. For example, a latching relay may be used to connect an electrical device (e.g., inverter) to a second electrical device/system/network, such as an electrical grid. In such case, the latching relay may be used as a circuit breaker that automatically operates as an electrical switch designed to protect the electrical device (e.g., an inverter, a power converter) from damage (e.g., caused by excess current from an overload or short circuit), or to prevent a converter from supplying power to a malfunctioning utility grid, where the switch may have a feature for electronically connecting and/or disconnecting the electrical device to/from the grid.

Aspects of the disclosure provided herein include electrical devices that comprise a relay array comprising one or more latching relays. The one or more latching relays may be an effective solution to the problem of power consumption of an automatic switching circuit coupled or incorporated into an electrical device, when the device is connected to a second electrical device/system/network. Using the one or more latching relays may provide benefits of decreased amount of dissipated energy and decreased device size due to the relatively small size of the latching relays. Furthermore, latching relays are comparatively cost-effective solution for high current relays, such that using one or more latching relays may provide benefits of reduced manufacturing costs.

A latching relay may use a power pulse, e.g., an amount of power supplied to the latching relay temporarily (e.g., 100-1000 ms). The power pulse may generate a magnetic field at the control coil of the latching relay and activate an electromechanical mechanism that may change the switching contact configuration (e.g., conducting/connected/ON or non-conducting/disconnected/OFF). After the changing of the switching contact configuration, the latching relay may maintain the switching contact configuration (e.g., connected/ON or disconnected/OFF), even when the power pulse may be removed, potentially reducing the dissipated power during steady-state operation. The switching contact configuration may be maintained until a subsequent power pulse is applied, at which time the switching contact configuration changes/toggles back to the other configuration (e.g., disconnected/OFF or connected/ON). According to some aspects, the energy for generating the power pulse may be provided by the grid or a local power supply that is internal or external to the electrical device (e.g., inverter).

The use of one or more latching relays in a relay array and the need for a power pulse to change the switching contact configuration may require a distributed and/or redundant control system. The distributed control system may detect a fault or an interruption (e.g., overload, short-circuits) and may create one or more control signals. One or more control coil driver circuits may receive the one or more control signals and may generate an electric current passing through the control coil(s). The electric current may induce a magnetic field to activate the electromechanical mechanism of the relay and to change the switching contact configuration.

According to some aspects, the control circuit and system may support scenarios where an immediate disconnection from the grid or a malfunction of the local power supply occurs, such that the power source/energy required to generate the power pulse may be unavailable. Therefore, the control circuit may comprise or be coupled to a power bank (e.g., one or more capacitive elements (e.g., capacitors), a battery, or both) that may store enough energy to generate the power pulse to change the switching contact configuration.

According to some aspects, the latching relay may be a single-coil latching relay, a dual-coil latching relay or a multi-coil latching relay. A single-coil latching relay may use only one coil to set or reset the switch position, such that both positive and negative voltages may be applied across the single-coil. For example, when a positive voltage is applied, a current may flow in one direction and enter the relay into the set-state (e.g., relay switch closed). A negative voltage may reverse the current direction, placing the relay into the reset-state (e.g., switch opened).

A dual-coil latching relay may have a set-coil and a reset-coil. For example, when the set-coil is energized, the relay may enter the set-state (e.g., switch closed). Conversely, when the reset coil is energized, the relay may enter the reset-state (e.g., switch opened). The set-coil and the reset-coil might not be energized at the same time, but each of them may require its own power source or driver.

In aspects of the disclosure herein, two or more relay contacts of a relay array may be provided using a multi-pole relay module. A multi-pole relay module incorporates a plurality of relays in a single package. A multi-pole relay module may enable the use of a common control coil for more than one relay contact, thereby reducing the size and the costs of the system. For example, a dual-pole relay module may have two contacts controlled by a single control coil, making a second control coil surplus to requirements, thereby reducing the relay array size, the dissipated energy during operation, the manufacturing costs, and/or the like.

In aspects of the disclosure herein, the relays of the relay array may use a different electrical contact configuration (e.g., single-pole single-throw [SPST], single-pole double-throw [SPDT], double-pole single-throw [DPST]). For example, when the relay array comprises two or more relays, using a DPST relay (e.g., a pair of switches or relays actuated by a single coil) may reduce the consumed energy for driving the control coils of the relay.

In aspects of the disclosure herein, the control circuit and system may comprise a monitoring circuit that is used to detect and recover from controller malfunctions. The control circuit and system may include one or more hardware processors, digital signal processing [DSP] circuits, field programmable gate array [FPGA] devices, and/or the like. The monitoring circuit may provide redundancy for malfunctioning elements and circuits of the control system. For example, the monitoring circuit may receive a timer reset (e.g., a pulse width modulation [PWM] signal) from the controller at predetermined intervals (e.g., every 50 s). In case the timer reset was changed or has not arrived, the monitoring circuit may generate a signal to start a process (e.g., of driving the control coil to change the switching contact state/position and disconnect the electrical device from the grid). For example, a case where the timer reset was changed may be when the controller makes a decision to change the switching contact state/position to nonconducting/OFF and disconnect the electrical device. Another example for a case where timer reset was changed or has not arrived may be when the controller is malfunctioning and the monitoring circuit may function as a back-up and redundant element for the controller and may generate a signal for changing the switching contact configuration/position to nonconducting/OFF in order to disconnect the electrical device from the grid.

Reference is now made toFIG.1, which illustrates a diagram of an electrical circuit comprising a relay array according to aspects of the disclosure herein. System100includes a direct current (DC) power source (e.g., a photovoltaic [PV] solar panel, PV module, PV array/string, a DC-DC converter), a single-phase alternating current (AC) grid (e.g., one phase of a multiphase (e.g., three-phase) AC grid), and an inverter circuit11. The inverter circuit11may comprise a DC-AC converter1, inductive elements L1and L2, control circuit10, and a relay array13comprising relays RE1-RE4. Each of relays RE1-RE4comprises a corresponding switching contact SC1-SC4and a corresponding control coil CC1-CC4respectively.

According to some aspects, at least one of relays RE1-RE4may be a latching relay (e.g., a relay that may maintain either contact configuration/position indefinitely without power applied to the coil). For example, relays RE1and RE3may be latching relays, and relays RE2and RE4may be non-latching relays, such that each inverter output is connected to a relay leg featuring one latching relay and one non-latching relay. Connecting each inverter output to a relay leg featuring one latching relay and one non-latching relay may reduce the size, cost and losses of converter1compared to a design including two non-latching relay contacts to each output, and may be configured to operate in a reliable and safe manner.

The current path comprising relays RE1-RE2may be collectively referred to as a first relay leg (e.g., a bus, a phase). The first relay leg may further comprise inductive element L1. The current path comprising relays RE3-RE4and may be collectively referred to as a second relay leg. The second relay leg may further comprise inductive element L2. Each of the first relay leg and the second relay leg (e.g., a bus, a phase) may be connected between an output terminal of converter1to a corresponding grid connection terminal.

Each of the switching contacts SC1-SC4may be controlled by a corresponding control coil CC1-CC4respectively. Each of the control coils CC1-CC4may be driven by control signals C1-C4generated by control circuit10. Control circuit10may generate control signals C1-C4according to a logic system and input data received by control circuit10. For example, the input data may include a measurement of one or more electrical parameters of system100, an enable signal generated by a FPGA or controller, or an interruption detected (e.g., high voltage/current measurement) in one of the components of system100. The input data may be measured by one or more sensors (e.g., voltage/current sensor) incorporated into or coupled with inverter circuit11. The input data may also be or include measurements on one or more parameters of a grid (e.g., a single phase grid, or one phase of a multiphase grid) connected to the inverter output.

Inductive elements L1and L2may represent the inductance of various inductive elements coupled to the first and second relay legs, such as, for example, a filter inductor, differential inductor, common-mode-choke inductor, etc. The various inductive elements represented in L1and L2may be coupled with different elements along the relay leg. According to some aspects, some of the inductive elements may be coupled: (i) between an output terminal of converter1and a first switching contact (e.g., relay RE1, relay RE3); (ii) between a first switching contact and a second switching contact (e.g., between relays RE1and RE2, between relays RE3and RE4); and/or (iii) between a second switching contact (e.g., relay RE2, relay RE4) and the connection to the (e.g., single-phase) AC grid.

The input terminals of converter1may be coupled across a DC power source, and may input power to converter1during operation of converter1. Converter1may convert the DC power to an AC power, which depending on the state of the switching contacts SC1-SC4may enable electrical current flow through the first relay leg and second relay led to feed power to the AC grid. Electrical current may flow from the DC power source to the AC grid when all switching contacts are connected (ON) and conduct electricity.

Reference is now made toFIG.2, which illustrates a diagram of an electrical circuit according to aspects of the disclosure herein. System200includes a direct current (DC) power source (e.g., a photovoltaic [PV] solar panel, PV module, PV array/string, a DC-DC converter), a three-phase alternating current (AC) grid and inverter circuit21comprising DC-AC converter2, inductive elements L3-L5, control circuit20and a relay array23comprising relays RE5-RE10. Each of relays RE5-RE10comprises a corresponding switching contact SC5-SC10and a corresponding control coil CC5-CC10respectively.

According to some aspects, at least one of relays RE5-RE10may be a latching relay (a relay that may maintain either conducting/ON or non-conducting/OFF contact configuration/position indefinitely without power applied to the coil).

The current path comprising relays RE5-RE6may be collectively referred to as a first relay leg (e.g., a bus, a phase). The current path comprising relays RE7-RE8may be collectively referred to as a second relay leg. The current path comprising relays RE9-RE10may be collectively referred to as a third relay leg. Each of the first relay leg, the second relay leg, and the third relay leg may connect between an output terminal of converter2to a corresponding grid connection terminal and represent one of the three phases of the grid. The first, second, and third relay legs may include, or be connected in series to, inductive elements L3, L4and L5, respectively.

Each of the switching contacts SC5-SC10may be controlled by a corresponding control coil CC5-CC10. Each of the control coils CC5-CC10may be driven by a corresponding control signal C5-C10generated by control circuit20. Control circuit20may generate control signals C5-C10according to a logic system and input data received by control circuit20. For example, the input data may be a measurement of one or more electrical parameters of system200, an enable signal generated by a controller (e.g., FPGA, DSP), or an interruption detected in one of the components of system200. The input data may be measured by one or more sensors (e.g., voltage/current sensor) incorporated into or coupled with inverter circuit21.

Inductive elements L3-L5may represent the inductance of various inductive elements coupled across the corresponding relay leg, such as, for example, a filter inductor, differential inductor, common-mode-choke inductor, etc. The various inductive elements represented in L3-L5may be coupled with different elements along the relay leg (e.g., phase, bus). For example, according to some aspects, some of the inductive elements may be coupled: (i) between an output terminal of converter2and a first switching contact (e.g., relay RE5, relay RE7, relay RE9); (ii) between a first switching contact and a second switching contact (e.g., between relays RE5and RE6, between relays RE7and RE8, between relays RE9and RE10); and/or (iii) between a second switching contact (e.g., relay RE6, relay RE8, relay RE10) and the connection to the three-phase AC grid.

The input terminals of converter2may be coupled across a DC power source, which may input power to converter2during operation of converter2. Converter2may convert the DC power to an AC power, which depending on the state of the switching contacts SC5-SC10and the control signals C5-C10generated by control circuit20, may flow through the relay paths (e.g., first, second, and third relay legs) to feed power to the AC grid. Power may flow from the DC power source to the AC grid when all switching contacts are connected and conducting electricity.

Reference is now made toFIG.3, which illustrates a diagram of an electrical system300, an example of system100ofFIG.1, according to aspects of the disclosure. According to some aspects, a single relay contact in each relay leg may be a latching relay. For example, inFIG.3, relays RE1and RE3ofFIG.1are implemented with latching relays LRE1and LRE3comprising switching contacts SC1and SC3respectively and control coils CC1and CC3respectively.

According to some aspects, a plurality of relays (two or more) of the relay array may be implemented with a multi-pole relay module. For example, dual-pole relay35may comprise relays RE2and RE4that may share a common control coil CC5(elements denoted CC5in the figure may be the same element) driven by control signal C5which may be generated by control circuit10. For example, using a dual-pole relay module35may provide the benefits of reduced size of electrical system300, reduced dissipated energy during operation of electrical system300, and/or reduced manufacturing costs.

In this example, the current path comprising latching relay LRE1and relay RE2may be collectively referred to as a first relay leg. The current path comprising latching relay LRE3and relay RE4may be collectively referred to as a second relay leg. Each of the first relay leg and the second relay leg may be connected between an output terminal of converter1to a corresponding grid connection terminal.

In this example, DC-AC converter1, inductive elements L1and L2, control circuit10, and a relay array33comprising relays RE2, RE4and latching LRE1and LRE3may be collectively referred to as inverter circuit31.

Reference is now made toFIG.4, which illustrates a diagram of an electrical system400, an example of system100ofFIG.1, according to aspects of the disclosure. According to some aspects, each relay leg may comprise at least two latching relays. For example, inFIG.4, relays RE1-RE4ofFIG.1are implemented with latching relays LRE1-LRE4respectively, which comprise switching contacts SC1-SC4respectively and control coils CC1-CC4respectively.

In this example, the current path comprising latching relays LRE1-LRE2may be collectively referred to as a first relay leg. The current path comprising latching relays LRE3-LRE4may be collectively referred to as a second relay leg. Each of the first relay leg and the second relay leg may be connected between an output terminal of converter1to a corresponding grid connection terminal.

According to some aspects, a plurality of relays (two or more) of different relay legs (e.g., first relay leg and second relay leg) of the relay array may be implemented with a multi-pole relay module. For example, according to some aspects, latching relays LRE2and LRE4may share a first common control coil driven by a first common control signal generated by control circuit10, and latching relays LRE1and LRE3may share a second common control coil driven by a second common control signal. Using a dual relay module may provide the benefits of reduced size of electrical system400, reduced dissipated energy during operation of electrical system400, and reduced manufacturing costs.

According to some aspects, latching relays LRE1-LRE4may be incorporated into a single module having one or more control coils. The digital logic of control circuit10may be used to generate control signals C1-C4. Where regulations might not require more than one control coil for each relay leg, a single control coil may control all of latching relays LRE1-LRE4. Where regulations require control coil redundancy, more than one control coil may be used, as described above.

In this example, DC-AC converter1, inductive elements L1and L2, control circuit10, and a relay array43comprising latching relays LRE1-LRE4may be collectively referred to as inverter circuit41.

Reference is now made toFIG.5, which illustrates a diagram of an electrical system500, an example of system200ofFIG.2, according to aspects of the disclosure.

According to some aspects, at least one of the relays or relay contacts of at least one relay leg may be a latching relay. For example, inFIG.4, relays RE5and RE10ofFIG.1are implemented with latching relays LRE5and LRE10respectively comprising switching contacts SC5and SC10respectively and control coils CC5and CC10respectively.

In this example, the first current path that connects converter2and the three-phase grid and comprises latching relay LRE5, relay RE6, may be collectively referred to as a first relay leg. The second current path that connects converter2and the three-phase grid and comprises relays RE7-RE8may be collectively referred to as a second relay leg. The third current path that connects converter2and the three-phase grid and comprises latching relay LRE10, relay RE9may be collectively referred to as a third relay leg.

According to some aspects, a plurality of relays (two or more) of the relay array may be implemented with a multi-pole relay module. For example, dual-pole relay55may comprise relays RE6and RE8that may share a common control coil CC4(elements denoted CC4in the figure may be the same element) driven by control signal C4, which may be generated by control circuit20. Dual-pole relay65may comprise relays RE7and RE9that may share a common control coil CC3(elements denoted CC3in the figure may be the same element) driven by control signal C3, which may be generated by control circuit20. Using dual-pole relay modules55and65may provide benefits of reduced size of electrical system500, reduced dissipated energy during operation of electrical system500, and reduced manufacturing costs.

In this example, DC-AC converter2, inductive elements L3-L5, control circuit20and a relay array53comprising relays RE6, RE7-RE9, and latching relays LRE5and LRE10may be collectively referred to as inverter circuit51.

According to some aspects, latching relays LRE5and LRE10may be incorporated into a single module (e.g., dual-pole relay) having one or more control coils. The digital logic of control circuit20may be used to generate control signals C1and C2.

According to some aspects, the relay array53may be controlled by only two control signals generated by control circuit20, where latching relay LRE5and dual-pole relay65may share a common control coil driven by a common control signal, and latching relay LRE10and dual-pole relay55may share a common control coil driven by a common control signal.

Reference is now made toFIG.6, which illustrates a diagram of an electrical system600, an example of system200ofFIG.2, according to aspects of the disclosure. According to some aspects, each relay leg may comprise at least two latching relays. For example, inFIG.6, relays RE5-RE10ofFIG.2are implemented with latching relays LRE5-LRE10respectively, which comprise switching contacts SC5-SC10respectively and control coils CC5-CC10respectively.

According to some aspects, relay array63may be controlled by only two control signals generated by the control circuit. For example, latching relays LRE5, LRE7and LRE9may be controlled by a first common control signal C1generated by control circuit20and latching relays LRE6, LRE8and LRE10may be controlled by a second common control signal C2.

According to some aspects, the relay array63may be controlled by a separate control signal, generated by the control circuit, for each of the latching relays. For example, each latching relays LRE5, LRE7, LRE9, LRE6, LRE8and LRE10may be controlled by a different control signal generated by control circuit20.

According to some aspects, a plurality of relays of different relay legs/paths (e.g., the first relay leg, second relay leg and third relay leg) of the relay array may be implemented with a multi-pole relay module. For example, latching relays LRE5, LRE7and LRE9may share a common control coil. Using a multi-pole relay module may provide benefits of reduced size of electrical system600, reduced dissipated energy during operation of electrical system600, and reduced manufacturing costs.

According to some aspects, latching relays LRE5-LRE10may be incorporated into a single module having one or more control coils. The digital logic of control circuit20may be used to generate control signals C1-C2.

In this example, DC-AC converter2, inductive elements L3-L5, control circuit20and relay array63comprising latching relays LRE5-LRE10may be collectively referred to as inverter circuit61.

Reference is now made toFIG.7, which illustrates a diagram of an electrical system700, an example of system200ofFIG.2, according to aspects of the disclosure. According to some aspects, at least one single relay in each relay leg of the relay array may be a latching relay. For example, inFIG.7, relays RE5, RE7, and RE9ofFIG.2are implemented with latching relays LRE5, LRE7, and LRE9respectively, which comprise switching contacts SC5, SC7, and SC9respectively and control coils CC5, CC7, and CC9respectively. Relays RE6, RE8, and RE10may be single pole relays.

According to some aspects, the relay array may be controlled by only two control signals generated by the control circuit. For example, in theFIG.7example, latching relays LRE5, LRE7, and LRE9may be controlled by a first common control signal C1generated by control circuit20and relays RE6, RE8, and RE10may be controlled by a second common control signal C2.

According to some aspects, a plurality of relays (two or more) of different relay legs (e.g., first relay leg, second relay leg, and third relay leg) of the relay array may be implemented with a multi-pole relay module. For example, latching relays LRE5, LRE7, and LRE9may share a common control coil. Using a multi-pole relay module may provide benefits of reduced size of electrical system700, reduced dissipated energy during operation of electrical system,700and reduced manufacturing costs.

In this example, DC-AC converter2, inductive elements L3-L5, control circuit20and a relay array comprising latching relays LRE5, LRE7, and LRE9and relays RE6, RE8, and RE10may be collectively referred to as inverter circuit71.

Reference is now made toFIG.8, which illustrates a diagram of an electrical system810according to aspects of the disclosure.

In this instance, DC-AC converter3, inductive elements L3-L6, control circuit20and a relay array comprising relays RE11-RE18(each comprising a corresponding switching contact SC11-SC18and a control coil CC11-CC18respectively) may be collectively referred to as inverter circuit81. The input terminals of inverter circuit81may be coupled across a DC power source (e.g., a photovoltaic [PV] solar panel, PV module, PV array/string, a DC-DC converter), and the output terminals of inverter circuit81may be coupled with a three-phase grid comprising phases L7, L8, and L9.

The relay array comprising one or more relay legs may connect DC-AC converter3to the three-phase grid. The current path comprising relays RE11-RE12may be collectively referred to as a first relay leg. The current path comprising relays RE13-RE14may be collectively referred to as a second relay leg. The current path comprising relays RE15-RE16may be collectively referred to as a third relay leg. Each of the first relay leg, the second relay leg and the third relay leg may connect between an output terminal of converter2to a corresponding grid connection terminal (e.g., phases L7, L8and L9).

According to some aspects, an electrical circuit (e.g., inverter) connected to a three phase grid may comprise a neutral leg, which may connect an output terminal of the electrical circuit to a neutral point of the grid (e.g., to a neutral conductor connected to a common point of a wye configuration shown inFIG.8).

For example, inFIG.8inverter81may comprise a neutral leg comprising relays RE17-RE18and inductive elements L6, which may connect between an output terminal of DC-AC converter3to a neutral point of the three-phase grid.

According to some aspects, the relay array may be controlled by only two control signals generated by the control circuit. For example, in this instance, relays RE11, RE14, RE15, and RE18may be controlled by a first common control signal C1generated by control circuit20and relays RE12, RE13, RE16, and RE17may be controlled by a second common control signal C2.

According to some aspects, each relay of the relay array may be controlled by a different control signal generated by the control circuit. For example, each one of the relays RE11-RE18may be controlled by a corresponding control signal generated by control circuit.

According to some aspects, a plurality of relays (two or more) of different relay legs (e.g., first relay leg, second relay leg, third relay leg, and neutral leg) of the relay array may be implemented with a multi-pole relay module. For example, relays RE11, RE14, RE15, and RE18may share a first common control coil and relays RE12, RE13, RE16, and RE17may share a second common control coil. Using a multi-pole relay module may provide benefits of reduced size of electrical system810, reduced dissipated energy during operation of electrical system810, and reduced manufacturing costs.

According to some aspects, at least one of the relays RE11-RE18of the relay array may be a latching relay. Using a latching relay may provide benefits of reduced size of electrical system810, reduced dissipated energy during operation of electrical system810, and reduced manufacturing costs.

Reference is now made toFIG.9, which illustrates a diagram of an electrical system900according to aspects of the disclosure.

In aspects of the disclosure herein, a connection box including one or more relay legs may connect a plurality of electrical circuits (e.g., inverters) to a grid. Each relay leg may comprise one or more relays and/or relay contacts. The use of such a connection box may enable reducing the number of relay contacts in each of the electrical circuits (e.g., inverters). For example, a circuit having five three-phase inverters coupled with a connection box may comprise a total of 18 relay contacts—one relay for each phase in each inverter (15 relays) and one relay for each phase in the connection box (three relays). If each inverter were to be compliant with a grid code requiring two contacts between each phase output of the inverter and the grid, without a connection box, the circuit would have 30 relays, two relays for each phase in each inverter.

According to some aspects, the use of a connection box may also reduce the number of control signals that control the relays. Referring to the example above, a circuit having five three-phase inverters coupled with a connection box may comprise 18 relay contacts controlled by six control signals—each inverter having a common control signal that controls all three relay contacts in that inverter (five control signals) and one control signal that controls all three relay contacts in the connection box. Without a connection box, the circuit may feature at least ten control signals—at least two control signals for each inverter—to comply with grid codes/standards requiring the two contacts for each phase to be independent controlled.

A connection box may provide, according to some features, additional benefits of reduced power consumption and reduced manufacturing costs. According to some aspects, the connection box may include additional circuits providing more features, for example, a potential-induced degradation (PID) reversal circuit, power supply, communication circuits (e.g., RS-485 communication circuit, power-line communication circuit, Wi-Fi communication circuit, Zigbee communication circuit), gate/coil driver circuits, controller (e.g., digital signal processor), etc. The communication circuit may be used to implement a maximum power point tracking (MPPT) algorithm to keep a PV system operating at, or close to, the peak power point of a PV panel under varying conditions, like changing solar irradiance, temperature, etc.

According to some aspects, a connection box comprising a first relay leg and a second relay leg may connect a plurality of electrical circuits (e.g., inverters) to a single-phase grid or one phase of a multiphase grid. The use of a connection box may reduce the number of relays required in a system and reduce the number of control signals, providing benefits of reduced power consumption and reduced manufacturing costs.

For example, three single-phase inverters101A,101B, and101C may be coupled to connection box105. The input terminals of each single-phase inverter101(e.g.,101A,101B, and101C) may be coupled across a DC power source (e.g., DC A, DC B, and DC C), and the output terminals of each single-phase inverter (e.g.,101A,101B, and101C) may be coupled to connection box105.

Each single-phase inverter (e.g.,101A,101B, and101C) may comprise a DC-AC converter1A/1B/1C, a control circuit10A/10B/10C, inductive elements L1-L2(e.g., L1A-L2A, L1B-L2B, L1C-L2C—a filter inductor, a differential inductor, a common-mode-choke inductor) and a relay array comprising relays RE1and RE3, each relay comprising a switching contact (e.g., RE1A and RE3A, RE1B and RE3B, and RE1C and RE3C having SC1A and SC3A, SC1B and SC3B, and SC1C and SC3C, respectively). Each single-phase inverter101(e.g.,101A,101B, and101C) may comprise a first relay leg and a second relay leg connecting output terminals of a DC-AC converter1(e.g., converter1A, converter1B and converter1C) to input terminals of connection box105. The first relay leg may comprise a first relay (e.g. RE1A, RE1B, RE1C) and a first inductive element (e.g., L1A, L1B, L1C) and the second relay leg may comprise a second relay (e.g., RE3A, RE3B, RE3C) and a second inductive element (e.g., L2A, L2B, L2C).

First switching contact SC1and second switching contact SC3of each single-phase inverter101may be controlled by a common control coil (e.g., elements denoted CC5in the figure may be the same element, elements denoted CC6in the figure may be the same element and elements denoted CC7in the figure may be the same element) driven by a single control signal (e.g., C5, C6and C7respectively) generated by a corresponding control circuit10A/10B/10C.

According to some aspects, first switching contact SC1and second switching contact SC3of each single-phase inverter101A/101B/101C may be controlled by different control coils driven by different control signals.

Connection box105may comprise control circuit15, a first connection terminal T1(e.g., line) connecting the first relay legs of each single-phase inverter101A/101B/101C, and a second connection terminal T2(e.g., neutral) connecting the second relay legs of each single-phase inverter101A/101B/101C.

Connection box105may further comprise a first relay leg and a second relay leg. The first relay leg may connect between first connection terminal T1to a first grid-connection of the single-phase grid or one phase of a multiphase grid (e.g., line/neutral). The second relay leg may connect between second connection terminal T2to a second grid-connection of the single-phase grid or one phase of a multiphase grid (e.g., line/neutral). Each of the first relay leg and the second relay leg may comprise one or more relays (e.g., RE2and RE4respectively) having switching contacts (e.g., SC2and SC4respectively) and inductive elements (e.g., L3and L4respectively).

Switching contact SC2and switching contact SC4of connection box105may be controlled and coupled with a common control coil (e.g., elements denoted CC4in the figure may be the same element) driven by a single control signal (e.g., C4) generated by control circuit15.

According to some aspects, each of switching contact SC2and switching contact SC4of connection box105may be controlled and coupled with a different control coil driven by a different control signal.

According to some aspects, connection box105may be a standalone box (e.g., an intermediate box separate from, but located at the same premises as, inverters101A/101B/101C) or incorporated into an electrical circuit, for example into one of single-phase inverters101A/101B/101C or into a different inverter (not shown). In some examples, the inverters101A/101B/101C may be located close to their respective DC power source (e.g., to reduce power loss), whereas the connection box105may be positioned in a more convenient location.

According to some aspects, connection box105may comprise two or more relays in each of the first relay leg and the second relay leg. For example, in addition to relays RE2and RE4, the first relay leg and the second relay leg may comprise a third and a fourth relay respectively, such that connection box105may comprise in total four relays (i.e., two relays for phase/line and two relays for neutral). In such case, inverters101A/101B/101C might not comprise relays and control circuits10A/10B/10C of inverters101A/101B/101C and control circuit15of connection box105may share control logic or communicate with each other to support proper operation of electrical system900(e.g., synchronization of waking up processes, power generation timing, etc.).

Inductive elements L1A, L2A, L1B, L2B, L1C, L2C, L3and L4may comprise inductance values of various inductive elements coupled across the relay legs, for example, a filter inductor, differential inductor, common-mode-choke inductor, etc. The various inductive elements represented in L1A, L2A, L1B, L2B, L1C, L2C, L3, and L4may be coupled with different elements along the relay leg. According to some aspects, inductive elements L1A, L2A, L1B, L2B, L1C, L2C, L3, and L4may be coupled: (i) between an output terminal of converter1A/1B/1C and a first switching contact (e.g., relay RE1A/B/C, relay RE3A/B/C), or (ii) between a first switching contact and an output terminal of single-phase inverters101A/101B/101C. According to some aspects, inductive elements L1A, L2A, L1B, L2B, L1C, L2C, L3, and L4may be coupled: (i) between first connection terminal T1or second connection terminal T2and switching contact SC2or switching contact SC4, respectively, or (ii) between switching contact SC2or switching contact SC4and a connection to the (e.g., single-phase) AC grid.

According to some aspects, a plurality of relays (two or more) of different relay legs of the relay array may be implemented with a multi-pole relay module. For example, relays RE1A/RE1B/RE1C and RE3A/RE3B/RE3C may be incorporated into a first dual-pole relay module sharing a first common control coil, and relays RE2and RE4may be incorporated into a second dual-pole relay module sharing a second common control coil. Using a dual-pole relay module may provide benefits of reduced size of single-phase inverters101A/101B/101C and connection box105, reduced dissipated energy during operation, and reduced manufacturing costs.

According to some aspects, at least one of the relays RE1A/RE1B/RE1C, RE3A/RE3B/RE3C, RE2, and RE4of the relay array may be a latching relay. Using a latching relay may provide benefits of reduced size of single-phase inverters101A/101B/101C and connection box105, reduced dissipated energy during operation, and reduced manufacturing costs.

According to some aspects, electrical system900may comprise one or more control circuits. For example, one of single-phase inverters101A/101B/101C or connection box105may comprise a control circuit similar to control circuit10ofFIG.1.

According to some aspects, connection box105may comprise additional circuits providing more features, for example potential-induced degradation (PID) circuit, power supply, communication circuits (e.g., RS-485 communication circuit, power-line communication circuit, Wi-Fi communication circuit, Zigbee communication circuit), gate/coil driver circuit, controller (e.g., digital signal processor), current/voltage sensors, etc. The communication circuit may be used to implement a maximum power point tracking (MPPT) algorithm to keep a PV system operating at, or close to, the peak power point of a PV panel under varying conditions, like changing solar irradiance, temperature, etc.

According to some aspects, control circuit15may communicate (e.g., send/receive data) with control circuits10A/10B/10C through communication circuits (e.g., RS-485 communication circuit, power-line communication circuit, Wi-Fi communication circuit, Zigbee communication circuit). For example, control circuit may send control circuits10A/10B/10C a command (e.g., PLC signal) to connect/disconnect the relays, one or more electrical parameters (e.g., voltage, current) of the AC grid. In another example, one of control circuits10A/10B/10C may send control circuit15a signal indicating that the corresponding DC power source is malfunctioning, not generating power, etc.

Reference is now made toFIG.10, which illustrates a diagram of an electrical system1000according to aspects of the disclosure.

According to some aspects, a connection box205may comprise a first relay leg, a second relay leg, and a third relay leg that may connect a plurality of electrical circuits (e.g., inverters) to a three-phase grid. The use of such a connection box may reduce the number of relays required in a system and reduce a number of control signals, thereby providing benefits of reduced power consumption and reduced manufacturing costs.

For example, in this instance, three three-phase inverters201A/201B/201C may be coupled with connection box205. The input terminals of each three-phase inverters201A/201B/201C may be coupled across a DC power source (e.g., photovoltaic [PV] solar panel, PV module, PV array/string, a DC-DC converter), and the output terminals of each of the three-phase inverters201A/201B/201C may be coupled with connection box205.

Each of the three-phase inverters201A/201B/201C may comprise a DC-AC converter2A/2B/2C, control circuit20A/20B/20C, inductive elements L3A-L5A/L3B-L5B/L3C-L5C (e.g., a filter inductor, a differential inductor, a common-mode-choke inductor), and a relay array. The relay array for inverter201A may comprise relays RE5A, RE7A, and RE9A. The relay array for inverter201B may comprise relays RE5B, RE7B, and RE9B. The relay array for inverter201C may comprise RE5C, RE7C, and RE9C. Each of these relays comprises at least one switching contact SC5A, SC7A, SC9A, SC5B, SC7B, SC9B, SC5C, SC7C, and SC9C. Each of the three-phase inverters201A/201B/201C may comprise a first relay leg, a second relay leg, and a third relay leg connecting between output terminals of DC-AC converter2A/2B/2C to input terminals of connection box205. The first relay leg may comprise a first relay (e.g. RE5A/RE5B/RE5C) and a first inductive element (e.g., L3A/L3B/L3C), the second relay leg may comprise a second relay (e.g. RE7A/RE7B/RE7C) and a second inductive element (e.g., L4A/L4B/L4C), and the third relay leg may comprise a third relay (e.g. RE9A/RE9B/RE9C) and a third inductive element (e.g., L5A/L5B/L5C).

First switching contact SC5A/SC5B/SC5C, second switching contact SC7A/SC7B/SC7C and third switching contact SC9A/SC9B/SC9C of each of the three-phase inverters201A/201B/201C may be controlled and coupled with a common control coil (e.g., elements denoted CC3in the figure may be the same element, elements denoted CC4in the figure may be the same element, and elements denoted CC5in the figure may be the same element) driven by a single control signal (e.g., C3, C4and C5respectively) generated by a corresponding control circuit20A/20B/20C.

According to some aspects, first switching contact SC5A/SC5B/SC5C, second switching contact SC7A/SC7B/SC7C, and third switching contact SC9A/SC9B/SC9C of each of the three-phase inverters201A/201B/201C may be controlled and coupled with a different control coil driven by a different control signal.

Connection box205may comprise control circuit25, a first connection terminal T1connecting the first relay legs of each three-phase inverter201A/201B/201, a second connection terminal T2connecting the second relay legs of each three-phase inverter201A/201B/201C, and a third connection terminal T3connecting the third relay legs of each three-phase inverter201A/201B/201.

Connection box205may further comprise a first relay leg, a second relay leg, and a third relay leg. The first relay leg may connect between first connection terminal T1to a first grid-connection of the three-phase grid. The second relay leg may connect between second connection terminal T2to a second grid-connection of the three-phase grid. The third relay leg may connect between third connection terminal T3to a second grid-connection of the three-phase grid. Each of the first relay leg, the second relay leg, and the third relay leg may comprise one or more relays (e.g., RE6, RE8, and RE0respectively) having switching contacts (e.g., SC6, SC8, and SC0respectively). According to some aspects, each of the first relay leg, the second relay leg, and the third relay leg may comprise inductive elements, such as a filter inductor, a differential inductor, or a common-mode-choke inductor.

Switching contact SC6, switching contact SC8, and switching contact SC0of connection box205may be controlled and coupled with a common control coil (e.g., elements denoted CC1in the figure may be the same element) driven by a single control signal (e.g., C1) generated by control circuit25.

According to some aspects, each of switching contact SC6, switching contact SC8, and switching contact SC0of connection box205may be controlled and coupled with a different control coil driven by a different control signal.

According to some aspects, connection box205may be a standalone box (e.g., an intermediate box separate from, but located at the same premises as, inverters201A/201B/201C) or incorporated into an electrical circuit, for example into one of three-phase inverters201A/201B/201C or into a different inverter (not shown).

According to some aspects, connection box205may comprise additional circuits providing more features, such as, for example, a potential-induced degradation (PID) circuit, a power supply, communication circuits (e.g., RS-485 communication circuit, power-line communication circuit, Wi-Fi communication circuit, Zigbee communication circuit), a gate/coil driver circuit, a controller (e.g., digital signal processor), a current/voltage sensor, a DC switch, a DCD (configured to switch off in the event of a drop out or a failure of one or more components of circuit1000), an AC switch, etc.

According to some aspects, connection box205may comprise a protection circuit, such as a surge protector detection circuit (or device) designed to detect and protect electrical devices from voltage spikes, an overheating detection circuit comprising thermistors (e.g., coupled to the power lines), fuse(s), etc.

According to some aspects, connection box205may comprise a pre-commissioning circuit, configured to ensure that electrical system1000is safe and performing as per its specifications prior to connecting electrical system1000to the AC three-phase grid. The connection box may comprise an inner/outer connection to a power bank circuit, configured to provide power for pre-commissioning tests (for example, relay test, isolation test, mapping, etc.). The power bank circuit may provide safe DC power to the pre-commissioning circuit, such that with/without a connection to the AC grid the pre-commissioning tests may be performed. The pre-commissioning circuit may be an important feature especially for large photovoltaic systems where a connection to the AC grid may require a significant time.

Inductive elements L3-L5(e.g., L3A, L3B, L3C, L4A, L4B, L4C, L5A, L5B, and L5C) may comprise inductance values of various inductive elements coupled across the relay legs, such as, for example, a filter inductor, differential inductor, common-mode-choke inductor, etc. The various inductive elements represented in L3-L5may be coupled with different elements along the relay leg. According to some aspects, inductive elements L3-L5may be coupled between an output terminal of converter2and a first switching contact (e.g., relay RE5A/RE5B/RE5C, relay RE7A/RE7B/RE7C, relay RE9A/RE9B/RE9C), or between a first switching contact and an output terminal of three-phase inverters201A/201B/201C.

According to some aspects, a plurality of relays (two or more) of different relay legs of the relay array may be implemented with a multi-pole relay module. For example, relay RE5A, relay RE7A and relay RE9A may be incorporated into a first three-pole relay module sharing a first common control coil, and relays RE6, RE8and RE0may be incorporated into a second three-pole relay module sharing a second common control coil. Using a multi-pole relay module may provide benefits of reduced size of three-phase inverters201A/201B/201C and connection box205, reduced dissipated energy during operation, and reduced manufacturing costs.

According to some aspects, at least one of the relays RE5-RE9and RE0of the relay array may be a latching relay. Using a latching relay may provide benefits of reduced size of three-phase inverters201and connection box205, reduced dissipated energy during operation, and reduced manufacturing costs.

According to some aspects, electrical system1000may comprise one or more control circuits. For example, one of three-phase inverters201or connection box205may comprise a control circuit similar to control circuit20ofFIG.2.

According to some aspects, a relay leg of connection box205may comprise three different relay legs of three-phase inverters201. For example, a relay leg of connection box205may comprise a first relay leg of a first inverter201, a second relay leg of a second inverter201, and a third relay leg of a third inverter201.

According to some aspects, control circuit25may communicate (e.g., send/receive data) with control circuits20A/20B/20C through communication circuits (e.g., RS-485 communication circuit, power-line communication circuit, Wi-Fi communication circuit, Zigbee communication circuit). For example, control circuit may send control circuits20A/20B/20C a command (e.g., PLC signal) to connect/disconnect the relays, one or more electrical parameters (e.g., voltage, current) of the AC grid. In another example, one of control circuits20A/20B/20C may send control circuit25a signal indicating that the corresponding DC power source is malfunctioning, not generating power, etc.

According to some aspects, connection box205may comprise two or more relays in each of the first relay leg and the second relay leg. For example, in addition to relays RE6, RE8, and RE0, the first, second, and third relay leg may comprise a fourth, a fifth, and a sixth relay respectively, such that connection box205may comprise in total six relays (i.e., two relays for each phase). In such case, inverters201A/201B/201C might not comprise relays and control circuits20A/20B/20C of inverters201A/201B/201C and control circuit25of connection box205may share control logic or communicate with each other to support proper operation of electrical system1000(e.g., synchronization of waking up processes, power generation timing, etc.).

Reference is now made toFIG.11a, which illustrates a relay array (or part thereof) with a safety catch (e.g., a pin, a toggle, an electronic safety pin).

In aspects of the disclosure herein, the relay array may comprise a safety catch, such as a disconnect lock pin, designed to prevent the latching relay from premature conduction. For example, the safety catch may prevent the latching relay from turning ON before a suitable time to begin feeding power from the device to the grid or from the grid to the device. The safety catch may prevent the electromechanical mechanism that controls the switching contact from making a connection of the switching contact, thereby ensuring that before and during the installation of the electrical device comprising the relay array to the grid, no current flows from the circuit to the grid, or vice versa. In contrast to electromagnetic relays that are in a known ON or OFF state depending on whether the coil is activated or not, latching relays may toggle/change between ON/OFF states in response to power pulses and include a mechanical latch that can change states due to mechanical forces, such as vibrations and contact with other objects that may occur during transportation of the system to the installation site. Therefore, the safety catch may ensure that an initial state of a latching relay is the OFF state. Without the safety catch, an installer of a system using latching relays might have to take additional steps to make sure the latching relays are initially set to the OFF state, which may result in higher costs of installation and reduced reliability due to human error in installing the system. Thus, the safety catch may make it practical to use latching relays in the electrical device (e.g., inverter). The safety catch may comprise a mechanical or an electrical mechanism (e.g., lever, magnet, handle) that may enable a removal of the safety catch. A removal of the safety catch may enable, with an occurrence of a power pulse, a connection of the switching contact. After the installation is completed, the safety catch may be removed by the installer, to enable turning the relay contacts ON and connecting the circuit to the grid.

InFIG.11a, relay array1100comprising a plurality of latching relays16may be incorporated into an electrical system (e.g., an inverter). Each latching relay16may comprise an electromechanical switching contact18and control pins19. The control pins19may be connected through control signal transmission lines/conductors to a component that may generate or transmit control signals (e.g., controller, digital signal processing [DSP], field programmable gate array [FPGA]). Each latching relay16may comprise terminals (not shown in the figure) connected to terminals of the corresponding bus/grid/line.

Each electromechanical switching contact18may have two states/positions. A first state/position may be when the upper horizontal surface of switching contact18may have a partial or a full contact with the surface of the body of the corresponding latching relay16. When switching contact18is at the first state/position, the switching contact18may be connected mechanically and electrically and the corresponding latching relay16may conduct. A second state/position may be when the upper horizontal surface of switching contact18may have a gap from the surface of the body of the corresponding latching relay16. When switching contact18is at the second state/position, the switching contact18may be disconnected mechanically and electrically and the corresponding latching relay16may be open-circuited.

Each latching relay16may have an electromechanical/electrical/mechanical mechanism (e.g., lever, magnet, handle) that, based on receiving a control signal through corresponding control pins19, may change the state/position of the corresponding switching contact18, from the first state/position to the second state/position and vice-versa. In the absence of receiving a control signal, latching relay16and the corresponding switching contact18may remain at the last state/position (e.g., the first state/position or the second state/position).

According to some aspects, relay array1100may be coupled to a safety catch12. Safety catch12may be held fixed by a locking mechanism14(e.g., a nut, linchpin, clasp, etc.), which may be coupled with an element of the electrical system or incorporated into the electrical system. In this instance, safety catch12may be threaded through an aperture (e.g., micro-aperture) of locking mechanism14.

Safety catch12may be located between the upper horizontal surface of switching contact18and the surface of the body of the corresponding latching relay16, thereby preventing the upper horizontal surface of switching contact18from creating a contact with the surface of the body of the corresponding latching relay16, and enforcing latching relay16and the corresponding switching contact18to be at the second state/position (e.g., disconnected and open-circuited).

In this instance, locking mechanism14may enable a removal of safety catch12only by pulling safety catch12out in the vertical axis of the surface of locking mechanism14(e.g., in the direction that the arrows indicate). When safety catch12may be pulled out of the gap between the upper horizontal surface of switching contact18and the surface of the body of the corresponding latching relay16, the electromechanical mechanism of latching relay18may be able to, based on receiving a control signal through corresponding control pins19, change the state of corresponding switching contact18to the first state/position.

In some instances, safety catch12may be a disposable safety pin, which is designed (e.g., made of plastic, rubber, or a similar cost-effective material, which may be insulating) for a single use after which it is recycled or disposed.

The safety pin of relay array1100ofFIG.11amay be incorporated into any of the relay arrays illustrated inFIGS.1-10.

Reference is now made toFIG.11b, which illustrates a safety catch incorporated into an electrical system (e.g., an inverter). As highlighted by the dashed circle inFIG.11b, safety catch26(similar to safety catch12ofFIG.11a) may be coupled with casing30of inverter1101. For example, the safety catch25may extend from the latching relay(s) inside an inverter through an aperture (e.g., hole, opening, etc.) in the casing30to an area outside the inverter. This provides a person (e.g., installer of the inverter) with a means for removing the safety catch26conveniently (e.g., without having to remove a lid or casing of the inverter). Safety catch26may be held fixed by one or more locking mechanisms (not shown in this figure), such as the example locking mechanism14ofFIG.11athat may be incorporated into casing30. As long as safety catch26may be located inside inverter1101, the latching relays18ofFIG.11amay be at the second state/position and not conduct.

In this instance, a removal of safety catch26may be possible by pulling safety catch25out in the vertical axis of the surface of casing30. Pulling the safety catch26in this manner may be the only practical way (e.g., without damaging the inverter) of removing the safety catch26. When safety catch26may be pulled out of the casing30, the electromechanical mechanism of latching relays18ofFIG.11amay be able to, based on receiving a control signal through corresponding control pins19ofFIG.11a, change the state/position of corresponding switching contact18ofFIG.11ato the first state/position and to conduct.

Reference is now made toFIG.12, which illustrates a block diagram of a control circuit (or part thereof). InFIG.12, diagram1200comprises control circuit91that, based on receiving input data97, may provide control coil driver circuits94with control signals (S3, S5). Based on control signals (S3, S5), control coil driver circuits94may drive at least two control coils of latching relays (for example, latching relays LRE1and LRE3ofFIG.3or latching relays LRE5-LRE10ofFIG.6) to supply the control coils with a power pulse that may generate a magnetic field at the control coil and activate an electromechanical mechanism that may change the switching contact state/position (e.g., conducting/ON or nonconducting/OFF).

Power digital signal processing (DSP)92, controller (e.g., field-programmable gate array (FPGA)/complex programmable logic device (CPLD)93/embedded controller, digital logic circuit, etc.), disconnection & monitoring circuit95, and power bank96may be collectively referred to as control circuit91. Control circuit91may be similar to control circuit10ofFIG.1or control circuit20ofFIG.2. Control circuit91may be incorporated into an electrical device (e.g., inverter), a relay, a connection box, a relay array, etc.

Control coil driver circuits94may receive power to drive the corresponding control coil by power supplies Vdc+ and Vdc−.

According to some aspects, based on input data97(e.g., a measurement or an estimation of electrical parameters of the electrical circuit, an enable signal, an external command) or a decision made by power DSP92, control circuit91may generate control signal S3(e.g., connection signal) that may command control coil driver circuits94to connect the switching contact(s) of the corresponding latching relay(s) and connect the electrical circuit to the corresponding grid-phase.

According to some aspects, based on input data97that may indicate one or more detected interruptions, malfunctions, and trip-zones (e.g., an occurrence of an unsought high voltage or high current) of the electrical circuit or the grid coupled to the electrical circuit, control circuit91may generate control signal S5(e.g., disconnection signal) that may command control coil driver circuits94to disconnect the switching contact(s) of the corresponding latching relay(s) and disconnect the electrical circuit from the corresponding grid-phase.

Power DSP92may receive signal S8which includes various types of input data97(e.g., current sensing, voltage sensing, temperature sensing). Based on: (i) an analysis; (ii) a programmed algorithm; and/or (iii) dynamic decision making, power DSP92may generate control signal S1to indicate FPGA/CPLD93whether to connect, disconnect, or maintain the same states of the latching relays. FPGA/CPLD93may receive signal S7which includes various types of input data97(e.g., similar or different than signal S8) and may also have the option to decide on a disconnection from the grid, generally when a hardware failure (e.g., a trip-zone) occurs. In such scenarios, FPGA/CPLD93may generate signal S2to inform power DSP of the disconnection and the cause for the disconnection. In this manner, FPGA/CPLD93may also function as a back-up and redundant element for power DSP92, in case of a malfunction of power DSP92.

With a decision of connecting the electrical circuit to the grid, FPGA/CPLD93may generate a predetermined signal S3(e.g., a pulse) to indicate control coil driver circuits94to drive the control coils of the latching relays and generate a connection of the switching contacts.

FPGA/CPLD93may also generate signal S4, thereby providing disconnection & monitoring circuit95a timer reset that indicates when to control the control coil driver circuits94to disconnect the latching relay. In some examples, signal S4may be a pulse width modulation (PWM) signal (for example, a signal having a duty-cycle of 50%) except for predetermined scenarios. For example, a scenario wherein FPGA/CPLD93may differentiate signal S4from a PWM signal may be when signal S1indicates FPGA/CPLD93to disconnect the latching relays and the electrical circuit from grid-phase or when FPGA/CPLD93makes a decision to disconnect from the grid-phase. For instance, in such a scenario FPGA/CPLD93may generate signal S4as a DC signal.

With an occurrence of signal S4that may be different than a PWM signal, disconnection & monitoring circuit95may generate signal S5to control the control coil driver circuits94to disconnect the latching relays and the electrical circuit from grid-phase.

In some instances, a signal S4that may be different than a PWM signal may occur when one of the power supplies Vdc+ and Vdc− is out of order or malfunctioning. Therefore, disconnection & monitoring circuit95may be coupled with power bank96(e.g., energy reservoir), which may store a predetermined amount of energy to drive the control coils. The predetermined amount of energy may be above a threshold, which indicates the minimum energy required to generate a power pulse that may change the state of the switching contact(s) of the latching relay(s). In such cases, power bank96may provide disconnection & monitoring circuit95with a power pulse P1.

In some instances, control circuit91may control and ensure charging of power bank96to a level above the threshold. Power bank96may be charged from one or more power sources coupled to control system91or incorporated into control system91. A plurality of power sources may provide benefits of redundancy.

In some instances, power DSP92may sense or take a measurement of some electrical parameters (e.g., voltage, current, power, temperature) of power bank96by sending or receiving signal S9.

A sub-circuit of control circuit91or a circuit coupled to control circuit91(not shown) may ensure a storage of an amount of energy above the threshold throughout the operation of the circuit.

Disconnection & monitoring circuit95may comprise a timing circuit that may control the time interval of generating signal S5. The time interval may be above a minimum time required to drive the control coils.

Monitoring circuit95may provide redundancy for scenarios where FPGA/CPLD93may be out of order or malfunctioning. For example, in a scenario where FPGA/CPLD93may be out of order or malfunctioning, FPGA/CPLD93might not generate signal S4as a PWM signal and in response monitoring circuit95may start the control process to disconnect the latching relays.

Reference is now made toFIG.13, which illustrates a block diagram of a power bank circuit (or part thereof). Power bank131(e.g., energy reservoir) may store a predetermined amount of energy to provide a disconnection & monitoring circuit135with a power pulse for driving a control coil(s) of a latching relay(s).

The predetermined amount of energy may be above a threshold, which indicates the minimum energy required to generate a power pulse that may generate a magnetic field at the control coil and activate an electromechanical mechanism that may change the switching contact(s) state/position (e.g., conducting/ON or nonconducting/OFF) of the latching relay(s).

Disconnection & monitoring circuit135may be similar to disconnection & monitoring circuit95ofFIG.12or a different one. Disconnection & monitoring circuit135may be incorporated into an electrical device (e.g., inverter).

DSP136may be similar to power DSP92ofFIG.12or a different one. DSP136may be incorporated into an electrical device (e.g., inverter).

Switching circuit133, storage134(e.g., capacitor(s), battery), and measurement circuit137may be collectively referred to as power bank131. Power bank131may be similar to power bank96ofFIG.12. Power bank131may be incorporated into an electrical device (e.g., inverter).

Power supply132may be a local power supply that is internal or external to the electrical device (e.g., inverter). Power supply132(e.g., auxiliary circuit) may provide power bank131with a DC voltage. A plurality of power supplies may provide benefits of redundancy.

Based on a decision to connect the electrical circuit to the grid, power supply132may provide power to charge storage134via switching circuit133. DSP136may generate control signal S11to control switching circuit133to connect or disconnect power supply132to storage134. Switching circuit133may, based on receiving signal(s) S11from power digital signal processing (DSP)136, conduct or not conduct power to charge or discharge, respectively, storage134.

In some instances, measurement circuit137(e.g., voltage sensor, voltmeter) may sense or take a measurement(s) of one or more electrical parameters (e.g., voltage, current, power, temperature) of storage134continuously or intermittently (e.g., periodically) to ensure that storage134stores a voltage/power level above the threshold. Measurement circuit137may send, to DSP136, an analog and/or digital signal(s) S10providing data that indicates the measurement(s) of one or more electrical parameters.

Based on a decision to disconnect the electrical circuit from the grid, DSP136might not generate signal S11(e.g., null voltage) to control switching circuit133to interrupt the power provided by power supply132to storage134, thereby causing a discharging of the power stored in storage134towards disconnection & monitoring circuit135to drive the control coil(s) of the latching relay(s) and generate a disconnection of the switching contacts.

Likewise, storage134may also provide disconnection & monitoring circuit135with an amount of energy that may be above a threshold (e.g., a predetermined amount of energy), in case of a malfunction of DSP136(or other reason that DSP136might stop sending signal S11).

Reference is now made toFIG.14, which illustrates a diagram of an electrical system1400according to aspects of the disclosure.

In aspects of the disclosure herein, an electrical circuit305may comprise a connection box320(e.g., similar to connection box205ofFIG.10a), including one or more relay legs that may connect the output of the electrical circuits (e.g., inverters) to a grid. Each relay leg may comprise one or more relays and/or relay contacts.

Electrical circuit305may connect the output of a plurality of DC power sources (e.g., photovoltaic [PV] solar panels, PV modules, PV arrays/strings, DC-DC converters) to the input of the electrical circuits (e.g., inverters). For example, as shown inFIG.14, electrical circuit305may comprise a plurality of input DC terminals DCin1, DCin2, DCin3, DCin4, DCin5, and DCin6. DC power sources DC A, DC B, and DC C may be coupled across a pair of input DC terminals DCin1-DCin2, DCin3-DCin4, and DCin5-DCin6, correspondingly.

Electrical circuit305may comprise a plurality of output DC terminals, for example output DC terminals DCout1, DCout2, DCout3, DCout4, DCout5, and DCout6ofFIG.14. A plurality of inverters (e.g., single-phase inverters, three-phase inverters) may be coupled to each pair of the output DC terminals. For example, three three-phase inverters301A,301B, and301C may be coupled to electrical circuit305. The input terminals of each three-phase inverter301(e.g.,301A,301B, and301C) may be coupled across a pair of the output DC terminals DCout1-DCout2, DCout3-DCout4, and DCout5-DCout6, correspondingly. The output terminals of each three-phase inverter301(e.g.,301A,301B, and301C) may be coupled to electrical circuit305through a plurality of input AC terminals of electrical circuit305, for example input AC terminals ACin1, ACin2, ACin3, ACin4, ACin5, ACin6, ACin7, ACin8and ACin9.

Each input AC terminal of the plurality of input AC terminals of electrical circuit305may be coupled to connection box320(optionally through additional circuit elements, such as a series resistor, a switch, an AC surge protection device (SPD), thermistor, sensor, etc.). The output of connection box320may be coupled to a plurality of output AC terminals. For example, connection box320may be coupled to a plurality of output AC terminals ACout1, ACout2and ACout3configured to provide power (e.g. an AC voltage, a sinewave voltage) to the AC grid (e.g., 3-PH AC Grid).

The use of such a connection box320may reduce the number of relay contacts in each of the electrical circuits (e.g., inverters). For example, a circuit having five three-phase inverters coupled with a connection box may comprise a total of 6 relay contacts (two relays for each phase in the connection box) or 18 relay contacts (one relay for each phase in each inverter and one relay for each phase in the connection box). If each inverter were to be compliant with a grid code requiring two contacts between each phase output of the inverter and the grid, without a connection box, the circuit would have 30 relays, two relays for each phase in each inverter.

According to some aspects, the use of a connection box may also reduce the number of control signals that control the relays. Referring to the examples above, a circuit having five three-phase inverters coupled with a connection box may comprise 6 relay contacts controlled by three control signals, and a connection box that may comprise 18 relay contacts controlled by six control signals—each inverter having a common control signal that controls all three relay contacts in that inverter (five control signals) and one control signal that controls all three relay contacts in the connection box. Without a connection box, the circuit may feature at least ten control signals—at least two control signals for each inverter—to comply with grid codes/standards requiring the two contacts for each phase to be independently controlled.

An electrical circuit, such as electrical circuit305, configured to receive DC power from a plurality of DC power sources, provide DC power to a plurality of DC/AC inverters, receive the AC power provided by the plurality of DC/AC inverters and provide AC power to the AC grid, may provide additional benefits of reduced power consumption and reduced manufacturing costs.

According to some aspects, electrical circuit, such as electrical circuit305, is configured to receive DC power from a plurality of DC power sources, provide DC power to a plurality of DC/AC inverters, receive the AC power provided by the plurality of DC/AC inverters and provide AC power to the AC grid. The electrical circuit may include optional additional circuits providing more features. By virtue of the use of some additional circuits as common circuits for the plurality of DC power sources and/or the plurality of DC/AC inverters, the electrical circuit (e.g., electrical circuit305) may provide additional benefits of reduced power consumption and reduced manufacturing costs.

For example, according to some aspects, the electrical circuit may comprise a fault or risk detection circuit, such as a surge protector detection circuit (or device) designed to detect and/or protect electrical devices from voltage spikes, an overheating detection circuit comprising thermistors (e.g., coupled to the power lines), fuse(s), etc. For example, electrical circuit305may comprise DC surge protection device (SPD)321and AC surge protection device (SPD)322. DC surge protection device (SPD)321may be coupled between the plurality of input DC terminals DCin1, DCin2, DCin3, DCin4, DCin5, and DCin6and the plurality of output DC terminals DCout1, DCout2, DCout3, DCout4, DCout5, and DCout6. AC surge protection device (SPD)322may be coupled between the plurality of output AC terminals ACout1, ACout2and ACout3and connection box320, or between connection box320and the plurality of input AC terminals ACin1, ACin2, ACin3, ACin4, ACin5, ACin6, ACin7, ACin8and ACin9. In case of an occurrence of voltage spike, overheating, etc., the DC SPD and/or AC/SPD may detect a fault. Based on the fault detection, a protection circuit (e.g., switch, relay, SPD, etc.) may disconnect electrical circuit305from the plurality of DC power sources and/or the plurality of DC/AC inverters, thereby protecting electrical circuit305. Electrical circuit305may comprise protection circuits, such as DC switch, a DCD (configured to switch off in the event of a drop out or a failure of one or more components of circuit1400), an AC switch, etc.

According to some aspects, the electrical circuit may comprise a common communication interface configured to communicate with the plurality of DC/AC inverters and/or the plurality of DC power sources (e.g., DC-DC converters). For example, connection box320may comprise communication interface323, which may be implemented as a RS-485 communication circuit, power-line communication circuit, Wi-Fi communication circuit, or Zigbee communication circuit. The communication interface may be used to implement a maximum power point tracking (MPPT) algorithm to keep a PV system operating at, or close to, the peak power point of a PV panel under varying conditions, like changing solar irradiance, temperature, etc.

According to some aspects, the electrical circuit may comprise a common potential-induced degradation (PID) circuit for the plurality of DC/AC inverters and/or the plurality of DC power sources (e.g., photovoltaic [PV] solar panels, PV modules, PV arrays/strings). For example, electrical circuit305may comprise PID circuit326and/or PID night circuit327. Using a common potential-induced degradation (PID) circuit may provide benefits of reduced size of electrical system1400, reduced dissipated energy during operation of electrical system1400, and reduced manufacturing costs.

According to some aspects, electrical circuit305may comprise a pre-commissioning circuit325, configured to ensure that electrical system1400is safe and performing as per its specifications prior to connecting electrical system1400to the AC three-phase grid. Electrical circuit305may comprise an inner/outer connection to a power bank circuit, configured to provide power for pre-commissioning tests (for example, relay test, isolation test, mapping, etc.). The power bank circuit may provide safe DC power to the pre-commissioning circuit325, such that with/without a connection to the AC grid the pre-commissioning tests may be performed. A centralized pre-commissioning circuit325for a plurality of inverters (e.g., single-phase inverters, three-phase inverters), for example three three-phase inverters301A,301B, and301C, may facilitate installation and commissioning process, thereby reducing commissioning and installation costs. The pre-commissioning circuit325may be an important feature especially for large photovoltaic systems where a connection to the AC grid may require a significant time.

According to some aspects, electrical circuit305may comprise power supply324. Power supply324may be used for initialization of system1400(for example, power generation after night time), pre-commissioning tests, power supply for control circuits30A,30B and30C of converters3A,3B and3C correspondingly, etc.

According to some aspects, electrical circuit305may comprise common rapid shut down (CRSD) circuit328. Common rapid shut down (CRSD) circuit328may be configured to discharge an electrical potential that built up due to parasitic capacitance. CRSD circuit328may be connected to one or more of the plurality of DC power sources (e.g., photovoltaic [PV] solar panels, PV modules, PV arrays/strings), e.g. input DC terminals DCin1, DCin2, DCin3, DCin4, DCin5, and DCin6. In some cases, the CRSD circuit328may be connected to a positive DC terminal (e.g., DC+ bus) and/or a negative terminal (e.g., DC− bus).

CRSD circuit328may include at least one discharge switch and at least one discharge resistor. For example, the at least one discharge resistor may be connected between a positive DC terminal (e.g., DC+ bus) and at least one discharge switch. The discharge switch may also be connected to a ground/earth potential. In other cases, discharge switch may be connected between a positive DC terminal (e.g., DC+ bus) and at least one discharge resistor, and the at least one discharge resistor may also be connected to a ground/earth potential.

As mentioned above, CRSD circuit328may be configured to perform discharge based on and/or in response to one or more indications that discharge should be performed, for example based on measurements done by sensing circuit329.

According to some aspects, electrical circuit305may comprise sensing circuit comprising one or more sensors. For example, electrical circuit305may comprise sensing circuit329comprising one or more sensors. Sensing circuit329may be used to determine one or more parameter indicative of circuit1400. Sensing circuit329may include, for example: a clock, a timer, a motion sensor, a magnetic sensor, a proximity sensor, a motion sensor, an irradiance sensor, a temperature sensor, a current sensor, a voltage sensor, a power sensor, etc. Based on the sensed parameter indicatives of circuit1400, other circuits of electrical circuit305may operate to implement its features, for example pre-commissioning circuit325, CRSD circuit328, initialization of system1400(for example, power generation after night time), etc.

Those skilled in the art will readily appreciate that various modifications and changes can be applied to the examples described without departing from the scope, defined in and by the appended claims, of the disclosure. Further, various modifications should be readily appreciated from the following paragraphs describing various combinations of features set forth in numbered clauses.

Clause 1: A circuit comprising: a relay leg configured to connect a power source to a grid via a first switching contact controlled by a first control coil and a second switching contact controlled by a second, different control coil, wherein at least one of the first switching contact or the second switching contact comprises a switching contact of an electromechanical relay (e.g., latching relay).

Clause 2: The circuit of clause 1, wherein the circuit is connected to a single phase of the grid.

Clause 3: The circuit of clause 1, wherein the circuit is connected to three phases of the grid.

Clause 4: The circuit of clause 1, wherein the circuit is connected to three phases of the grid and to a neutral conductor.

Clause 5: The circuit of any one of the preceding clauses, wherein the latching relay is configured to change a switching contact state in response to receiving power above a threshold.

Clause 6: The circuit of any one of the preceding clauses, further comprising a control circuit configured to, based on receiving input data, control the latching relay.

Clause 7: The circuit of clause 6, wherein the control circuit comprises a power bank configured to output power to change a state of the latching relay.

Clause 8: The circuit of any one of clauses 6 or 7, wherein the control circuit comprises a monitoring circuit configured to receive a signal from a controller at predetermined intervals.

Clause 9: The circuit of any one of clauses 6-8, wherein the control circuit is configured to: control, using a first control signal, the first switching contact; and control, using a second control signal, the second switching contact.

Clause 10: The circuit of any one of the preceding clauses, further comprising a safety catch configured to prevent the latching relay from conducting.

Clause 11: The circuit of clause 10, wherein the latching relay is configured to conduct based on a removal of the safety catch.

Clause 12: The circuit of any one of the preceding clauses, further comprising an inverter configured to receive electrical power from the power source and convert a direct current (DC) power into an alternating current (AC) power.

Clause 13: The circuit of any one of the preceding clauses, further comprising a second relay leg configured to connect the power source to the grid via a third switching contact and a fourth switching contact, wherein the third switching contact of the second relay leg and the first switching contact of the first relay leg are different switching contacts of a dual-pole relay module.

Clause 14: The circuit of any one of the preceding clauses, wherein the first control coil controls a third switching contact on a second relay leg different from the relay leg.

Clause 15: The circuit of any one of the preceding clauses, wherein the first switching contact is controlled by a multi-coil latching relay.

Clause 16: A system comprising: one or more electrical devices comprising: a first control circuit; a first relay leg comprising: a first switching contact connected to a first terminal and controlled by the first control circuit; and a second relay leg comprising: a second switching contact connected to a second terminal and controlled by the first control circuit; and a connection box comprising: a second control circuit; a first connection terminal connected to a grid via a third switching contact controlled by the second control circuit, wherein the first connection terminal is connected to the first terminal; and a second connection terminal connected to the grid via a fourth switching contact controlled by the second control circuit, wherein the second connection terminal is connected to the second terminal; wherein at least one of the first switching contact, the second switching contact, the third switching contact, or the fourth switching contact comprises a switching contact of an electromechanical relay (e.g., latching relay).

Clause 17: The system of clause 16, wherein the second control circuit is configured to communicate with the first control circuit.

Clause 18: The system of any one of clauses 16 or 17, wherein the first switching contact and the second switching contact are controlled by a first control coil.

Clause 19: The system of any one of clauses 16-18, wherein the first connection terminal is connected to a third terminal of a third relay leg, wherein the second connection terminal is connected to a fourth terminal of a fourth relay leg, and wherein the third relay leg and the fourth relay leg belong to a second electrical device different from a first electrical device comprising the first relay leg and the second relay leg.

Clause 20: The system of any one of clauses 16-19, wherein the one or more electrical devices comprises: a first electrical device comprising a first inverter configured to receive electrical power from a first power source and convert a first direct current (DC) power into a second alternating current (AC) power; and a second electrical device comprising a second inverter configured to receive electrical power from a second power source and convert a second direct current (DC) power into a second alternating current (AC) power.

Clause 21: The system of any one of clauses 16-20, further comprising a power bank configured to provide a power pulse sufficient to change a state of the latching relay.

Clause 22: A method, comprising: controlling, by a control circuit using at least a first power pulse, a relay leg to connect a power source to a grid, wherein the relay leg comprises a first switching contact and a second switching contact and at least one of the first switching contact or the second switching contact comprises a switching contact of a latching relay; and controlling, by the control circuit using at least a second power pulse, the relay leg to disconnect the power source from the grid.

Clause 23: The method of clause 22, wherein the using the first power pulse comprises supplying power for 100-1000 ms.

Clause 24: An apparatus comprising: a plurality of input DC terminals configured to receive DC power; a plurality of output DC terminals configured to provide DC power to a plurality of electrical circuits; a plurality of input AC terminals configured to receive AC power from the plurality of electrical circuits; a plurality of output AC terminals configured to provide AC power to a grid; and a connection box configured to connect the plurality of input AC terminals to the plurality of output AC terminals.

Clause 25: The apparatus of clause 24, wherein the plurality of output AC terminals comprise: a first connection terminal and a second connection terminal connected to the grid; wherein the connection box comprises: a control circuit; a first relay leg comprising: a first switching contact controlled by the control circuit and connected to the first connection terminal; and a second relay leg comprising: a second switching contact controlled by the control circuit and connected to the second connection terminal.

Clause 26: The apparatus of clause 25, wherein at least one of the first switching contact and the second switching contact comprises a switching contact of a latching relay.

Clause 27: The apparatus of any of claims 24-26, wherein the plurality of electrical circuits comprises a first electrical device comprising a first inverter configured to receive electrical power from a first power source and convert a first direct current (DC) power into a second alternating current (AC) power; and a second electrical device comprising a second inverter configured to receive electrical power from a second power source and convert a second direct current (DC) power into a second alternating current (AC) power.

Clause 28: The apparatus of any one of clauses 24-27, wherein each of the plurality of input DC terminals is configured to receive DC power from at least one of a photovoltaic solar panel, a PV module, a PV array/string, or a DC-DC converter.

Clause 29: The apparatus of any one of clauses 24-28, wherein the connection box comprises: a third relay leg comprising: a third switching contact controlled by the control circuit and connected to a third connection terminal connected to the grid.

Clause 30: The apparatus of any one of clauses 24-29, wherein the apparatus is connected to a single phase of the grid.

Clause 31: The apparatus of any one of clauses 24-30, wherein the apparatus is connected to three phases of the grid.

Clause 32: The apparatus of any one of clauses 24-31, wherein the apparatus is connected to three phases of the grid and to a neutral conductor.

Clause 33: The apparatus of any one of clauses 24-32, wherein the latching relay is configured to change a switching contact state in response to receiving power above a threshold.

Clause 34: The apparatus of any one of clauses 26-33, wherein the control circuit is configured to control, based on receiving input data, the latching relay.

Clause 35: The apparatus of any one of clauses 25-34, wherein the control circuit comprises a power bank configured to output power to change a state of the latching relay.

Clause 36: The apparatus of any one of clauses 25-35, wherein the control circuit comprises a monitoring circuit configured to receive a signal from a controller at predetermined intervals.

Clause 37: The apparatus of any one of clauses 25-36, wherein the first relay leg further comprises: a third switching contact controlled by the control circuit and connected to the first switching contact; and the second relay leg further comprises: a fourth switching contact controlled by the control circuit and connected to the second switching contact.

Clause 38: The apparatus of any one of clauses 25-36, wherein the control circuit is configured to: control, using a first control signal, the first switching contact; and control, using a second control signal, the third switching contact.

Clause 39: The apparatus of any one of clauses 25-38, wherein the control circuit is configured to: control, using the first control signal, the second switching contact; and control, using the second control signal, the fourth switching contact.

Clause 40: The apparatus of any one of clauses 26-39, further comprising a safety catch configured to prevent the latching relay from conducting.

Clause 41: The apparatus of clause 40, wherein the latching relay is configured to conduct based on a removal of the safety catch.

Clause 42: The apparatus of any one of clauses 24-41, further comprising a communication interface, wherein the communication interface comprises one of: a RS-485 communication circuit, a power-line communication circuit, a Wi-Fi communication circuit, or a Zigbee communication circuit.

Clause 43: The apparatus of any one of clauses 24-42, further comprising a fault detection circuit configured to detect an occurrence of fault or risk to the apparatus.

Clause 44: The apparatus of any one of clauses 24-43, further comprising one of an AC surge protector detection circuit, a DC surge protector detection circuit and an overheating detection circuit.

Clause 45: The apparatus of any one of clauses 24-44, further comprising a power supply configured to provide DC power.

Clause 46: The apparatus of any one of clauses 24-45, further comprising a pre-commissioning circuit configured to perform tests prior to connecting the apparatus to the grid.

Clause 47: The apparatus of any one of clauses 24-46, further comprising a potential-induced degradation (PID) circuit.

Clause 48: The apparatus of clause 47, wherein the potential-induced degradation (PID) circuit is configured to operate during nighttime.

Clause 49: The apparatus of any one of clauses 24-48, further comprising a sensing circuit configured to determine one or more parameters indicative of the apparatus.

Clause 50: The apparatus of any one of clauses 24-49, further comprising a common rapid shut down circuit configured to discharge an electrical potential due to parasitic capacitance.

Clause 51: The apparatus of clause 50, wherein the common rapid shut down circuit comprises a switch and at least one resistor.