KR20120134085A - Power generator module connectivity control - Google Patents

Abstract

PURPOSE: A power generator module connection control is provided to prevent damage caused by lightning by using a lightning rod for separating overvoltage from a ground. CONSTITUTION: A sensing element detects a control signal(240-S) from a generator module. The generator module which is serially connected is selectively connected to a switch. A controller controls the switch based on the control signal from a power line(250). The generator module in a string includes an anode and a cathode. [Reference numerals] (220-1,220-2,220-N) Power generator module; (220-P) Power; (230) Load; (240) Control signal generator; (240-S) Control signal; (250) Power line; (260) Voltage; (280) Output power

Description

Generator module connection control {POWER GENERATOR MODULE CONNECTIVITY CONTROL}

Related application

This application is related to and claims priority to US Provisional Patent Application No. 61 / 491,359, filed March 31, 2011, entitled “Photovoltaic Module Latch.” The entire contents are incorporated herein by reference.

This application is related to and claims priority in US Patent Application No. 61 / 579,437, filed December 22, 2011, entitled "Photovoltaic Module Level Disconnect." The entire contents of the application are incorporated herein by reference.

Conventional PhotoVoltaic (PV) power systems generate power used in many types of applications. For example, in one conventional application, the power generated by a solar cell array can be used to charge a battery that makes power available during non-daylight times.

1 illustrates a typical PV array 105 (eg, a plurality of PV elements 135 connected in series) that drives an inverter or charger load 110. Each photovoltaic module 135 may generate up to 10 amps at direct current 50 volts.

As shown, the PV module 135 may raise a direct current voltage generated by being connected in series. In some cases, if the string of PV modules contains a sufficient number of modules connected in series, the voltage generated by the string of PV modules may be about 1000 Vdc or more.

Parallel strings in PV modules can increase the total DC current beyond 200 amps. Thus, remote disconnection and reconnection of power provided by a photovoltaic power system may be desirable as a safety feature that typically enables manual or automatic system suspend near the load.

In some cases, a defect in one string can cause excessive reverse current from the other string. Therefore, each string may need its own fuse or breaker.

1 also includes a capacitor 114 representing the input capacitance typically found in a load such as an inverter or a charger. A fuse 115 (or breaker) between the negative (-) terminal of the PV module array 105 and each ground 116 helps to cancel current between the PV array 105 and each ground 116. . The arrester element 118 helps protect the PV array 105 from damage due to lightning strikes by branching excess voltage to ground 116.

The power system may include a DC switch 120 that provides the ability to disconnect the load (eg, inverter / charger 110) from the PV array 105. However, disconnection and reconnection of photovoltaic power near the load 110 does not guarantee that the current and voltage levels are secured between the PV module system and the DC switch 120, which is why, for example, firefighters and PV system management personnel, etc. Potential risks to emergency handling personnel.

The present invention seeks to provide a generator module connection control.

In contrast to conventional applications, embodiments of the present invention allow a user to solely control the connection of the power system. For example, each generator module (eg, power supply, photovoltaic power generation resource, etc.) in a corresponding string of a plurality of generator modules connected in series has a respective control circuit. The control circuit may have a controller for driving a switch in the generator module. The individual generator module has an output terminal, and voltage is generated across the output terminal when the generator resource of the generator module (eg, a power source such as a plurality of PV cells) is exposed to sunlight. The generator module can be selectively activated in series connection to generate a voltage that is used to power external loads such as inverters, optimizers, chargers, and the like.

According to another embodiment, the remote resource may be configured to control the connection of the generator module in the string. For example, each generator module may include a current sensing circuit that monitors for the presence of a communication signal from the control signal generator. More specifically, each PV module monitors for remotely generated keep-alive signals (ie activation signals) transmitted over the power lines used by each generator module to deliver power to external loads. can do. If a sustain signal is present on the power line as generated by the remote resource, the control circuit of the individual generator module activates the switch on (or keeps each PV module active) so that each activated generator module To be connected in series with one or more other activated generator modules in the serial string. In one embodiment, if no sustain signal is detected within the timeout period, each generator module deactivates each generator module.

Each generator module in the string may include a bypass capacitor disposed substantially between its output terminals. Control signals for controlling one or more generator modules in the string are AC-type signals (e.g., sine wave, quasi-sine wave, sawtooth wave, etc.) that are transmitted through the power line to each generator module in the string to turn on. Square wave pulses). The bypass capacitor of the generator module provides a low impedance path that enables the transfer of communication signals to other generator modules downstream of the series connection, since the capacitor passes the AC control signal and blocks the DC signal. Thus, the plurality of generator modules in each string can each receive a communication signal.

Embodiments of the present invention provide a diode disposed between terminals of a generator module to enable use of a relay of a low voltage FET (field effect transistor) or a series control switch (e.g., a low cost switch) disposed in each generator module ( For example, circulating diodes, reflux diodes, module level bypass diodes). In one exemplary embodiment, the intrinsic diode of the field effect transistor also functions as a bypass diode that conducts string current when the series switch is disconnected to enable the use of low voltage diodes between the terminals of the generator module. The over temperature and / or under voltage protections implemented herein may also reduce excessive power dissipation caused by high FET on resistance or relay contact resistance. For example, in one embodiment, the undervoltage protection of each generator module includes an undervoltage protection on each generator module of the string when there is a transient condition such as an arc fault or ground fault that shorts the array or string power lines together. Turning off each switch provides the additional system benefit of reducing the available power supplying transient conditions.

According to another embodiment, switching noise generated by an external load (e.g., power converter, charger, etc.) is accompanied by the removal of the power line signal, since the noise can be interpreted as a simple, continuous "continuous" signal. Can be reduced or eliminated. The simple continuous "continuous" signal generator described herein allows the use of low cost control circuits in each generator module that do not need to demodulate or decode the signal.

In a further embodiment, the module level control device responds to manual or automatic activation of the remote disconnect switch by the emergency handling staff or the administrative staff, or by an arc fault or ground fault detector or by load (inverter, optimizer, Means for disconnecting each individual power source from the string or generator module by turning off the power line signal generator in response to automatic activation in cooperation with control of the charger. In addition, the sustain control signal may terminate when power supply to the sustain signal generator is interrupted, when the PV power line connection is opened, and / or when there is a short circuit between the power lines.

Modifications of the above and other embodiments are described in further detail below.

As noted above, various embodiments of the present invention may include configurations of one or more computerized devices, hardware processor devices, assemblers, etc. to implement and / or support some or all of the method operations described herein. Pay attention to In other words, one or more computerized devices, processors, digital signal processors, assemblers, and the like may be programmed and / or configured to perform the methods described herein.

In addition, although each of the different features, techniques, configurations, etc. described herein may be described elsewhere in this specification, it is intended that each concept may be executed independently of one another or in cooperation with each other. Accordingly, one or more of the inventions, embodiments, and the like described herein may be embodied and viewed in many different ways.

It is also noted that the above preliminary description of embodiments of the invention does not specify various embodiments and / or incrementally novel aspects of the invention or claimed invention herein. Instead, this brief description presents only general embodiments and / or corresponding novelty parts over the prior art. For further details and / or possible correlations (substitutions) of the present invention, reference may be made to the 'details for carrying out the invention' section of the present specification and corresponding drawings, which are described in more detail below.

According to the present invention it is possible to provide a generator module connection control.

1 shows an exemplary PV array according to the prior art.
2 shows an exemplary power system including a plurality of generator modules connected in series, according to an embodiment of the invention.
3 shows an exemplary generator module according to an embodiment of the invention.
4-6 illustrate exemplary locations where a power system may experience transients, in accordance with embodiments of the present invention.
7 illustrates an exemplary sustain circuit in accordance with an embodiment of the present invention.
8 shows an exemplary generator module according to an embodiment of the invention.
9 shows additional details of a series switch and control circuit in accordance with an embodiment of the present invention.
10 illustrates an example of generator module current vs. generator module voltage for a plurality of uniform radiation levels, in accordance with an embodiment of the present invention.
11 to 14 show a latch generator module according to an embodiment of the present invention.

The foregoing and other objects, features and advantages of the present invention will become apparent from the following more detailed description of the preferred embodiments of the present invention, as indicated by the accompanying drawings wherein like reference numerals designate like parts throughout the figures thereof. will be. The drawings are not necessarily to scale, focusing instead on describing embodiments, principles, concepts, and the like.

As mentioned above, embodiments of the present invention differ from conventional power generation systems.

More specifically, FIG. 2 illustrates exemplary control of series connection of a selectively activated generator module, in accordance with an embodiment of the present invention.

As shown, the power system 100 includes a plurality of generator modules 220 (eg, generator module 220-1, generator module 220-2, ..., generator module 220-N). At least one string consisting of, the control signal generator 240, and the load 230.

Note that power system 100 may include any suitable number of generator module 220 strings connected in parallel to generate voltage 260.

As its name suggests, control signal generator 240 generates one or more control signals 240-S for controlling generator module 220.

More specifically, in one embodiment, the control signal generator 240 generates a control signal 240-S that controls the functions associated with the generator module 220. For example, the control signal generator 240 transmits the control signal 240 -S to the generator module 220 through the power line 250. Each generator module 220 in the string receives a control signal 240-S. The generator module 220 receives the control signal 240 -S and performs each function according to the received control signal 240 -S.

In one embodiment, control signal generator 240 generates one or more control signals 240-S that activate each generator module 220 in the string. In one embodiment, the series connection of the activated generator module 220 generates a voltage 260 that is used to power the load 230.

Each generator module 220 in the string includes an anode (+) and a cathode (−) connected in series to the power line 250 as shown. When activated, each generator module 220 generates a respective voltage between each anode terminal (+) and cathode terminal (−). Since the generator modules 220 in the string are connected in series as shown at activation, assuming there are no defects and each generator module generates a voltage, the output voltage 260 generated by the string of the generator modules 220 Is the sum of the individual output voltages produced by each generator module. The string of generator modules produces a string current at output voltage 260.

Thus, in accordance with the control signal generator 240, the string of the generator module 220 is controllable to deliver the generated power 220 -P to the load 230 through each power line 250 passing through the generator module. Can be connected in series.

The control signal generator 240 may interrupt the generation of control signals 240 -S (which may include one or more control signals) or send communications to the generator module 220 to deactivate them. In such a situation, the generator module 220 is turned off and no longer generates the voltage 260 used to drive the load 230.

As a non-limiting example, the voltage 260 generated in the string of the activated generator module 220 may be a substantially DC voltage.

Control signal 240-S may be any suitable type of signal. For example, in one embodiment, the control signal 240-S may be an AC signal that overlaps the voltage 260. In such a situation, generator module 220 uses an AC signal (eg, control signal 240-S) as a basis for determining whether each generator module should be activated to generate an output voltage between its terminals.

In this exemplary embodiment, the load 230 may be any suitable type of resource (eg, converting, regulating, or the like, the power 220 -P generated by the generator module 220 to the output power 280). For example, it may be an inverter, a charger, and the like.

The output power 280 can be used to power the load, and the load then consumes the output power 280 to perform certain functions. The load 230 can be configured to convert the voltage 260 into a 120 volt AC signal.

3 is an exemplary diagram illustrating more specific functionality associated with one or more generator modules in accordance with an embodiment of the present invention. Note that each generator module 220 may operate in a similar manner as described later.

As described herein, activating the switch 350 in the on state drives the switch 350 with a suitable signal to establish a low impedance path between each power source 340 and each cathode power terminal 360-2. It means to create. In this case, the switch 350 is closed.

Deactivating the switch 350 off means driving the switch 350 with a suitable signal to create a high impedance path between the power supply 340 and the cathode power terminal 360-2. In this case, the switch 350 is open.

As shown, generator module 220-2 includes controller 320, sensor element 330, power supply 340, switch 350, capacitor 371, bypass diode 372, and bleed resistor 373. ).

The power source 340 may be any suitable type of resource, such as a PV panel including a plurality of solar cells that collectively generate output currents at respective DC voltages. The PV panel may be configured to convert solar energy (ie, light energy) received from the sun into electrical energy. In one exemplary embodiment, the generator module 220 is a so-called photovoltaic (PV) type module that converts solar energy into electrical energy.

The switch 350 disposed in each generator module 220 may be any suitable type of resource, such as a field effect transistor, an electromechanical relay, or the like.

In one embodiment, controller 320 monitors for the presence of control signal 240-S generated by remotely located control signal generator 240 and received over power line 250. The controller 320 detects such a condition by receiving an input from the sensor element 330. Based on the input from the sensor element 330, the controller 320 receives communication from the control signal generator 240 indicating how to control the generator module 220-2.

Therefore, based on the control signal 240 -S received by the controller 320, the controller 320 controls the state of the switch 350. For example, the switch 350 selectively activates each generator module 220-2 of the generator module 220 connected in series.

More specifically, in a non-limiting example embodiment, if sensor element 330 receives a control signal 240-S indicative of the activation of each switch 350, controller 320 is sensor element 330. ) And generates an internal control signal for turning on the switch 350 in accordance with the detected control signal 240-S. In one exemplary embodiment, if the sensor element 330 does not detect the presence of the control signal 240-S indicative of the activation of each switch 350, the previous received from the control signal generator 240 After a predetermined timeout period has elapsed after receiving the activation control signal of, the controller 320 initiates deactivation to turn the switch 350 off.

Thus, according to one exemplary embodiment, the control signal 240-S may be a sustain signal. As long as the generator module 220-2 periodically or continuously detects the sustain signal generated by the control signal generator 240, the controller 320 activates the switch in the on state. The controller 320 deactivates the switch 350 in the OFF state after failing to detect the presence of the control signal 240 -S.

Note that sensor element 330 may be any suitable type of resource, such as a low impedance sensing element. For example, the low impedance element is placed in series in an electrical path extending between the anode power terminal 360-1 and the power supply 340 to be generated by the power supply 340 by causing current to flow along the low impedance path of the power line. The impact on the output voltage can be reduced.

The sensor element 330 may be any suitable type of resource, such as a current or voltage sensor element that detects the presence of the control signal 240 -S.

In one non-limiting example embodiment, the sensor element 330 is a transformer element in which the primary winding of the transformer is connected in series between the anode power terminal 360-1 and the power source 340. The controller 320 monitors the secondary winding of the transformer. In this example, the secondary winding of the transformer transmits the AC signal generated by the control signal generator 240 to the controller 320. The controller 320 may process this signal to determine whether the received signal is a valid sustained signal or noise. The power supply 340 may generate a DC current or voltage. The DC current flowing through the primary winding of the transformer does not generate a voltage across the secondary winding. Thus, sensor element 330 may be an AC sensing element that allows a DC element of a power signal to be delivered to load 230 via power line 250.

Note that as an alternative to being disposed in series in the path, the sensor element 330 may be a capacitor. The anode power terminal 360-1 may be directly coupled to the power source 340. One end of the sensor element 330 is coupled to the anode power terminal node 360-1, and the other end of the capacitor detects the presence (or absence) of at least the occasional AC signal generated by the control signal generator 240. It can be coupled to the sensing circuit of the controller 320. Thus, sensor element 330 may provide a voltage sensing capability to detect the presence of control signal 240 -S.

By installing a bypass capacitor 371 in each generator module of the series configuration or string, it is ensured that each generator module of the string receives at least a portion of the control signal 240-S generated by the control signal generator 240. can do. For example, each capacitor 371 installed in each individual generator module of the string forms part of a series connection of the plurality of generator modules 220. The capacitor 371 of the generator module acts as a voltage divider (so that AC current flows through the string) such that each generator module 220 receives at least a portion of the control signal 240-S substantially simultaneously. Accordingly, each generator module 220 includes a respective capacitor 371 disposed between the output terminals (eg, 360-1 and 360-2) of each generator module 220 to control signals 240-. S) may be transmitted through the power line 250.

Assuming all of the generator modules 220 in the string are initially disabled, or deactivated, each controller 320 transmits a control signal 240-S over the power line 250 to allow each controller 320 to substantially control the generator module 220. May initiate simultaneous activation (eg, turning on each switch 350) to generate an output voltage 260. In other words, the control signal 240 or the absence of the control signal enables simultaneous control of the generator module 220-2 since each generator module receives such signals substantially simultaneously.

Accordingly, the control signal generator 240 may be configured to generate the control signal 240 -S. The control signal generator 240 transmits the control signal 240 -S through the power line 250 to activate each of the plurality of generator modules 220 connected in series. The load 230 receives power via the power line 250 from the activating generator module 220 connected in series. As mentioned above, the control signal may be an AC signal. The power received via power line 250 may be substantially a DC voltage and / or a DC current generated by a series connection of a plurality of generator modules 220 simultaneously activated.

In one embodiment, the control signal generator 240 suspends transmission of the control signal 240-S via the power line 250 to deactivate each individual generator module of the plurality of generator modules 220 connected in series. May also be configured.

As already described, sensor element 320 may be configured to detect current. The control signal generator 240 generates the control signal 240-S as a pulse of current. As already explained, the controller 320 in each individual generator module 220 receives the signal and controls the switch 350 accordingly. According to another embodiment, the controller 320 compares the input received from the sensor element 330 with one or more thresholds (eg, first threshold, second threshold, etc.). The controller 320 activates the switch 350 in the on state in response to detecting that the current sensed by the sensor element 330 is greater than the first threshold. The controller 320 deactivates the switch 350 in an off state in response to detecting that the current sensed by the sensor element 330 is less than the second threshold. According to an embodiment, the magnitude of the first threshold may be greater than the second threshold. Alternatively, the first threshold and the second threshold may be substantially the same value.

The power line 250 may be sensitive to noise. For example, load 230 may perform a transition to convert voltage 260 to output power 280. In this embodiment, the operation of the control signal generator 240 and the load may be controlled and / or synchronized so that noise imposed on the power line 250 does not affect the control of the generator module 220.

As a more specific example, control signal generator 240 (ie, a remote signal generator) may be configured to generate control signal 240 -S as a sustain signal as described above. The control signal generator 240 can also provide a signal to stop the load, thereby blocking the load 230 related switching noise that the controller 320 in each generator module can interpret as a sustain signal.

Diode 372 in each individual generator module 220 causes each generator module to operate in bias mode if each switch 350 is not activated. The bias mode (eg, during deactivation of switch 350) allows each generator module 220 to pass current and / or voltage signals even when the generator module is in the off state.

For example, for some reason, the controller 320 of the generator module 220-2 failed to turn on the switch 350 in response to receiving the control signal 240-S, but other upstream and downstream connected in series. It is assumed that the generator module is activated upon receipt of the control signal 240 -S. In this case, since the switch 350 of the generator module 220-2 is inactive (off), the generator module 220-2 does not contribute to generating the output voltage 260. However, other activated generator modules each contribute to the generation of output voltage 260 due to the series connection configuration. The magnitude of the output voltage 260 is lower than in other cases in which the generator module 220-2 is active. That is, as a non-limiting example, if each active generator module contributes to the generation of X volts and only (N-1) possible generator modules in the string are activated, then the output voltage 260 of the string is substantially (N -1) X If all generator modules, including generator module 220-2, are active, output voltage 260 will have a magnitude of (N) X substantially.

In one embodiment, when control signal generator 240 stops generating control signal 240-S, controller 320 may operate each generator module 220-2 to operate in bypass mode. The switch 350 may be set to the off state. In other words, when no presence of the control signal 240-S is detected, each generator module may operate in bypass mode.

According to another embodiment, the diode 372 disposed between the output terminals 360-1 and 360-2 of each generator module 220-2 prevents the switch from being damaged by an overvoltage condition and thus switches 350. Note that it limits the bypass diode power dissipation in. Thus, the switch 350 is less likely to be damaged.

In addition, a diode 372 disposed between the terminals of the generator module 220 may have a respective angle, such as a low voltage FET (field effect transistor) or relay, for the series control switch (e.g., low cost switch) disposed in each generator module. Enable the use of the switch 350. If the switch 350 is a field effect transistor, the intrinsic diode of the field effect transistor may also act as a bypass diode. That is, the intrinsic diode of switch 350 conducts string current when the series switch is disconnected to enable overvoltage protection of diode 372.

As will be discussed in detail later, an over temperature and under voltage protection (eg, controller 320 monitors the regulated voltage generated by power supply 340, generating power to control circuitry or related circuitry). Turning the switch 350 off if the voltage is too low) may also reduce excess power dissipation resulting from high FET on resistance or relay contact resistance. This undervoltage protector opens an individual fault switch 350 in each generator module of the parallel string when there is a transient current such as an arc fault or ground fault that shorts the array or string power lines together. Provides additional system benefit of reducing available power supplying ground faults.

Accordingly, another embodiment of the present invention includes a generator module arranged in series connection of a plurality of generator modules. Each individual generator module disposed in series connection of the generator modules includes an anode power terminal 360-1; Cathode power terminal 360-2; And a diode 372 (that is, a diode element). The anode (+) end of diode 372 is coupled to the cathode power terminal 360-2 of each generator module via a low impedance electrical path.

As mentioned above, the switch 350 is disposed in series with a power source 340 that generates respective power. The switch 350 controls the application of the power generated by the power source 340 between the anode power terminal 360-1 and the cathode power terminal 360-2 of each generator module 220-2.

Switch 350 may be a field effect transistor with an intrinsic diode; The forward bias of the intrinsic diode supports current flow from the anode power terminal 360-1 through the power supply 340 to the cathode power terminal 360-2.

As shown, the combination of switch 350 in series with power source 340 may be disposed substantially in parallel with diode 372. The sensor element 330 of each generator module monitors for the presence of a communication signal received via power line 250 to which anode power terminal 360-1 and cathode power terminal 360-2 are connected in series. As already described, the controller 320 (ie, the control circuit) controls the state of the switch 350 in accordance with the control signal (ie, the communication signal).

Note that the control signal 240 -S generated by the control signal generator 240 need not be a continuous signal. Instead, the control signal generated by the control signal generator 240 may be encrypted such that the generator module receiving the control signal performs each function. For example, one type of control signal (eg, first encrypted communication) may be sent to the generator module to activate each switch 350. Another type of control signal (eg, second encrypted communication) may be sent to deactivate each switch 350.

Another embodiment may include targeting instructions to different generator modules. For example, each command may be encrypted with a target address value indicating whether the command should be directed to a string of generator modules or to a specific generator module in the string. The controller 320 may have suitable generator capability to decode the received signal and determine whether the received signal was directed to the receiving generator module. If so, the controller 320 can decode the command intended by the communication received from the control signal generator 240 to determine what function to perform.

Thus, generator module 220 may be controlled through the generation of other types of commands. The commands generated by the control signal generator 240 may be specifically targeted to different generator modules.

In reverse, another embodiment of the present invention may include communicating from each generator module 220 through a power line 250 to a control signal generator (or other suitable message processing resource). Each generator module 220 may be assigned a unique address. The generator module may include the address of the generator module in the message to allow the control signal generator that receives the message to identify which generator module 220 generated the message. Messages from the generator module may include status information such as the health of the power source 340 and the ability to generate power, voltages generated by the power source of the generator module, and the like. The generator module 220 may transmit a message for the control signal generator as an AC signal. The control signal generator 240 may include suitable circuitry to monitor for the presence of messages received from the generator module via the power line.

According to another embodiment, the generator module includes in the message a destination address (eg, the address of the generator module to which the communication is directed) and a source address (eg, the address of the generator module sending the communication). Can be configured to communicate with each other based on the.

According to another embodiment of the invention, FIG. 7 shows a parallel string of PV modules each having a switch and a control circuit. More specifically, a plurality of PV module strings with respective switches may be connected in parallel to generate a voltage 260.

In one particular embodiment, the "persistent" signal generator 740 is coupled with an optional arc fault detector (AFD) 741 and I / O to a load 230 such as an inverter, optimizer, charger, or the like. And a power line 750 through a current transformer 755.

Note that the current and / or voltage superimposed on power line 750 can be sensed with any suitable technique, including shunts, Hall effect sensors, flux gate magnetic sensors, and the like.

The "persistent" signal generator 740 may be a conventional narrowband unidirectional powerline communication generator that operates at a single frequency, for example, a single frequency typically between 9 kHz and 148 kHz, or at other frequencies allowed by international standards. . This signal generated by generator 740 may be amplitude modulated, frequency modulated, or phase modulated or encrypted to improve noise rejection. However, module-level-separation (MLD) circuits can be more complex and expensive because of the demodulation or decoding functionality required.

7 also shows the input 760 from the load 230 as PV module-level-separation (MLD) control means. Output 761 is also provided to block or reduce switching noise from load 230. The switching noise may in other cases generate a false "persistent" signal when it is desirable to deactivate the generator module as already described. In addition, the output signal from the load 230 to the controller 740 can be used to terminate the " persistent " signal.

Although FIG. 7 shows that the AFD 741 is located near the load 230, the AFD 741 may be located at a string level in or near the combiner box. In addition, a current transformer 755 for signal injection may be used for AFD 741 arc signal detection.

Although the current transformer 755 is shown in series connection with the positive end of the power line 750, the current transformer 755 may be connected in series with the negative end of the power line 750 or between the positive power line and the negative power line 750. Capacitors may be coupled. In the latter case, inductive chokes may be used in the positive and / or negative power lines to reduce the shorting effect of the input capacitance on the load 230.

If the AFD 741 detects a series or parallel transient as shown in FIGS. 4-6, the AFD may remotely isolate each module by deactivating the sustain signal generator 740. The AFD 741 may also send an output to the load 230 to block switching at its input, thus eliminating a potential source of false sustained signals.

The series connection of the generator modules can be separated by the opening of the string or array connection, the opening of the fuse or breaker in the string or array, and the short between the power lines.

8 shows that a series switch and a control circuit are attached to each individual PV module according to an embodiment of the invention.

In this exemplary embodiment, the series switch 350-1 and the power supply 340 are between terminals 360-1 and 360-2 supplying an output current (“Io”) and an output voltage (“Vo”). Form the output. Control circuit 320-1 includes an input from current sensing element 330-1 that monitors for the presence of a " persistent " signal. The overvoltage clamp element 810 prevents damage to the control circuit 320-1, and the load resistor 812 converts the primary winding current from the current sensing element 330-1 into a secondary voltage. As mentioned, field effect transistor (FET) 350-1 can be replaced with any suitable resource, such as an electromechanical relay, in which case the relay coil replaces the FET gate and the relay contacts replace the FET drain and source. do.

There are some known problems when using physical relays. The lifetime of a contact is in particular limited by the contact corrosion caused by switching at high voltages or high currents. Power dissipation resulting from the contacts can increase over time if the contact resistance increases due to contamination. Contacts may cause closure failures if insulating particles or films are formed between the contacts, and opening failures if the contacts are welded together. The coil can dissipate power when excited and a significant portion of power dissipate when the contacts are closed, thereby raising the temperature of the device and reducing the energy efficiency of the PV system. In addition, the size and cost of such relays can outperform semiconductor relays, and the electrical and mechanical lifetimes can be much lower than for semiconductor switches.

As shown in FIG. 10, other components persist through the PV string because the absolute or parallel impedance of the individual generator modules can attenuate the signal and the FET 350-1 in the off state will also attenuate the signal. And a bypass capacitor 371 for conducting the signal. Overvoltage protection (OVP) diode 372 enables the use of low voltage FET 350-1. The bleed resistor 373 discharges the power line voltage remaining in the capacitor 371.

The OVP diode 372 works with the PV module to limit the maximum voltage across the FET 350-1, and the FET 350-1 substrate diode (ie the intrinsic diode) works with the PV module to produce the OVP diode ( 372) Limit the reverse voltage at both ends. In this way, the module-level-separation (MLD) FET 350-1 and OVP diode 372 provide much higher string and array voltages (which increase the price of the FET 350-1 and OVP diode 372). For example, it is only necessary to withstand the continuous voltage associated with each power source 340 (ie, PV module), rather than the output voltage 260. The OVP diode 372 may also be a "active" diode with a low voltage drop and thus lower power dissipation when forward biased. The active diode may be a FET based device having a lower voltage drop than the forward biased FET substrate diode (eg, the intrinsic diode of FET 350-1).

Also shown in FIG. 8 is a PV power module (ie, power supply 340) and a plurality of bypass diodes 865. The bypass diode 865 bypasses any compartment of the power source 340 (eg, a plurality of PV solar cells) if the current in the compartment resulting from the radiation falls far below the other modules in the string. Function. Power dissipation in the PV module junction box 820 will increase as more of the bypass diodes 865 are forward biased.

If the temperature of the junction box or internal components becomes too high, the series FET 350-1 may be configured to be off so that each power source 340 is part of a series connection of the generator module. In other words, the control circuit 320-1 may be configured to shut off the switch 350-1 when it is detected that the temperature of the connection box 820 or a portion thereof is above the threshold. Thus, the control circuit 320-1 may ignore the command from the control signal generator 240 to deactivate the switch 350-1 in the off state. As mentioned, even when a single generator module 220 is operating in bypass mode, other serially connected generator modules may be activated to generate respective output voltages 260, although at low voltages. By shutting off each switch 350-1 in the generator module, it lowers its power dissipation and helps prevent damage caused by excessive heat.

9 shows a series switch and a control circuit attached to each PV module. Control circuit 320-1 includes an input from current sensor element 330-1. The control circuit 320-1 may include any of one or more components, such as a band pass filter, an amplifier, a peak detector, a comparator, a voltage regulator, and the like.

In one embodiment, the control circuit 320-1 includes an associated band pass filter and time constant (eg, between 1 millisecond and 100 milliseconds) for controlling changes in the open and closed states of the switch 350-1. ) To reduce the possibility of false turn-on due to noise.

As shown, each generator module may include a voltage regulator 816. The voltage regulator 816 can receive power from the power source 340. The output of the voltage regulator 816 powers the control circuit 320-1 and other related circuits in the generator module.

In one embodiment, when the sustain signal received from the control signal generator 240 falls below the threshold, the control circuit 320-1 controls the series FET 350-1 to be turned off to supply power 340. (E.g. PV modules) are separated from the string.

As described above, even when the generator module receives a command to turn on the switch 350-1, the other control circuit block in each generator module may be connected to a connection box (such as a bypass diode, control circuit 320-1, etc.). When the temperature of the monitored portion of 820 exceeds the safe operating temperature threshold Tth and the PV module voltage is reduced below the voltage threshold Vth, the regulated voltage is configured to isolate the power supply 340 from the string. Operate circuit 320-1 and make sure that FET 350-1 does not provide enough voltage to turn on with a low switch resistance.

For example, control circuit 320-1 may be configured to turn off switch 350-1 if switch 350-1 cannot be turned on using a sufficiently high gate voltage. If the gate voltage is too low, the on resistance of the switch 350-1 will be high, causing excessive heat dissipation and damage in the switch 350-1. When the FET switch 350-1 is turned off by the control of the control circuit 320-1, the terminal current Io flows through the OVP diode 372.

Each individual generator module may include a temperature sensor circuit. The control circuit 320-1 ignores the command to activate the switch 350-1 in response to detecting that the temperature associated with the individual generator module is above a threshold (ie, the control circuit 320-1 switches the switch 350). Turn -1) off).

The control circuit 320-1 may generate a power supply when the temperature drops below a predetermined threshold or when the module voltage Vpv (for example, the output voltage supplied by each power supply 340) rises above the predetermined threshold again. 340 is reconnected in series to the string (by reactivating switch 350-1). Reconnecting or reactivating the individual generator modules in series may be further controlled by time delay and some nominal threshold hysteresis to prevent rapid FET switch 350-1 or relay switch oscillation. Thus, each individual generator module controls the switch 350-1 to be in an off state in response to detecting that the voltage generated by the voltage regulator circuit has fallen below an undervoltage threshold to power the individual generator module. Level sensor circuitry.

According to the embodiment described herein, the magnitude of the current passing through each generator module string is determined by the following conditions: short circuit of the output voltage 260 of the string; Termination of control signal 240-S generation; Stopping the operation of the remote signal generator (eg, the control signal generator 240) according to the error condition; Opening of switch 350; Physical separation of the generator module from the string; And opening of a fuse element or circuit breaker disposed between the generator module and the load 230.

In case each string is isolated by a separate inverter, optimizer or charger, a separate signal generator can be attached to each string to separate the individual strings. In addition, a field effect transistor (FET) such as an N-type field effect transistor or the switch 350-1 shown in FIGS. 8 and 9 may be another type of transistor, for example, a bipolar junction transistor (BJT) or an insulated gate bipolar transistor. It is well known that it can be replaced with (IGBT) and can be in incremental mode or depletion mode.

Furthermore, any apparatus or method described in connection with FIGS. 7-9 may be, for example, an optimizer that adjusts the DC-DC conversion such that each string operates at its maximum power point, or each module is at its maximum power point. It is also possible to combine it with other functions such as a micro inverter that adjusts the DC-AC conversion to operate. The apparatus may also be combined with an arc fault detector attached to each photovoltaic module. In addition, a remote arc fault or ground fault detector coupled to a remote power line that disconnects or shorts the switch can be used with the apparatus or method described herein. Furthermore, simple analog circuit hardware is preferred, but other hardware, such as microcontrollers or ASICs (special purpose integrated circuits), can be used instead to implement the basic control described herein, which is enhanced by more complex signal processing.

FIG. 10 shows an exemplary graph 1000 of PV module current versus module voltage for three levels of uniform emissivity. The absolute module impedance (| Z |) changes as a function of the operating point, where Z is the incremental impedance at the operating point.

Optional Latch Type  Embodiment

According to a further possible embodiment, a control device attached to each photovoltaic power module is provided, which device comprises a switch connected in series with each module, an output terminal for interconnecting a string of power modules and an array of such strings. It includes a control circuit having a. External loads, such as inverters or chargers, are connected to the output of the string or array. Disconnecting each module by shorting the output of the string or array and reconnecting by externally raising the DC voltage of the output are made possible by the series switch and control circuit. This embodiment defines a method of latching the series switch and the internal load resistor in the required state using the output terminal voltage.

In another aspect of the invention, there is provided an apparatus attached to each photovoltaic power module, the apparatus comprising a series switch and a control circuit, and an output terminal for interconnecting a string of power modules and an array of such strings. External loads, such as inverters or chargers, are connected to the output of the string or array. Separation of each module by opening the output of the string or array and reconnection by externally raising the DC voltage of the output are made possible by the series switch and control circuit. This embodiment defines a method of latching the series switch and the internal load resistor in the required state using output terminal current and voltage.

As described later, latched PV modules may be pulsed by a current to latch each PV module in an on state. The PV module described below can be used as a replacement for the generator module described above. The PV module described below is a special type of generator module that latches upon receiving a current pulse signal from a remote source, such as control signal generator 240.

Now, in particular, FIG. 11 shows an exemplary state in which a PV module is coupled with a FET switch and control circuit electrically connected to an output terminal in accordance with an embodiment of the present invention.

The control circuit 1100 provides flexibility to predetermine terminal voltage thresholds for closing and opening the switch 1150. The control circuit 1100 latches the FET switch 1150 to closed and open. If output terminal 1170 is electrically isolated from an external power source or load, the state of FET switch 1150 does not change its state.

For example, if FET switch 1150 is closed, each PV module voltage maintains FET switch 1150 closed (ie, on) when output terminal 1170 is electrically isolated from an external power source. And if the FET switch 1150 is open (i.e., off), the predetermined internal load is opened (i.e., off), for example, if the output terminal 1170 is electrically disconnected from the external load. Or when the power line is disconnected between the short switch and the output terminal, the voltage across the output terminal is kept at a low voltage to open the FET switch 1150.

More specifically, capacitor C4 helps protect FET switch 1150 and control circuit 1100 against ESD (electrostatic discharge) and filters high frequency noise between positive and negative output terminals 1170. To help. When the FET (i.e., switch 1150) is open, the FET substrate diode (i.e., the intrinsic diode of the FET) and the PV module are connected to the bypass diode (D1) when an external power source, e.g. another PV string, increases the voltage across the output terminal. Limiting the voltage between the control circuit and the bypass diode (D1) and the PV module, the bypass diode (D1) and the PV module reduce the voltage between the bypass FET and the control circuit when an external power source, such as another PV module in the same string, reduces the voltage across the output terminal. Restrict. Capacitor C2, resistor R2 and zener diode Z2 are attached to the gate of the FET switch to control the switch response time, turn off the FET when there is no external gate drive, and protect the gate from overvoltage.

Power to the control circuit is provided by the PV module via a voltage regulator consisting of capacitor C1, zener diode Z1, diode D2 and resistor R1; Diode D2 prevents discharge of capacitor C1 through resistor R1 when the output terminals are shorted together and the FET switch is closed. The voltage across the output terminal is sensed by the comparator (CMP) and components R4, R3, C3, together with R5, R6, and R7, the components determine two voltage thresholds that determine when the comparator is switched , C3 provides the time delay between when the terminal voltage crosses one of the thresholds and when the comparator output is switched. Diode D4 prevents the input voltage of the comparator from reversing from being below the diode drop lower than the low power supply rail of the comparator. Components R8, T1, and D3 include a gate drive circuit connecting the comparator output and the FET gate; T1 converts the CMP output voltage into FET gate drive current and serves as a level shifter between the CMP circuit referenced in the positive PV module connection and the FET circuit referenced in the negative PV module connection; D3 prevents the voltage across the voltage regulator capacitor C1 from discharging through the base-collector junction of T1 and the zener diode Z2 when the output terminal voltage drops below the voltage across C1.

Components R11, T2, R9 and R10 provide special features not found in semiconductor relays. That is, an internal load is applied between output terminals when the voltage across the terminals is below a first predetermined threshold and the load is removed when the voltage is above a second predetermined threshold. This function maintains the FET open by keeping the output terminal voltage below the first predetermined threshold if the output terminal is electrically isolated from the external load, and internal if the output terminal voltage is above the second predetermined threshold. It is used to reduce internal power dissipation by removing the load.

12 illustrates a state in which a PV module is coupled with a FET switch and control circuit electrically connected to an output terminal according to an embodiment of the present invention.

As shown in Fig. 12, the control circuit provides an S-R latch function with an output Q. If the output current Iout falls below the predetermined first threshold current while the time-averaged output voltage is above the predetermined first threshold voltage (ie, the terminals are electrically disconnected from the external load), the control circuit 1200 latches (ie, turns off) the FET switch 1250 in an open state and reconnects the internal load. If the output voltage Vout rises above the predetermined second threshold voltage while the time averaged output current is below the predetermined second threshold current (ie by an external power supply), the control circuit 1200 closes the FET switch. Latch (ie, turn on) and disconnect the internal load.

The use of time-averaged current and voltage parameters is due, for example, to a reason why the SR latch is wrong, for example, when Iout is below a predetermined threshold because Vout is low, or when Vout is above a certain threshold in normal operation when Iout is high. Prevents it from being set or reset.

13 shows an exemplary state in which a PV module and a FET switch and control circuit electrically connected to an output terminal are coupled in accordance with an embodiment of the present invention.

As shown in FIG. 13, the control circuit 1300 provides an S-R latch function with an output Q, combining two remote disconnect methods (remote switch short or remote DC disconnect). 13 shows control logic in the control circuit 1300. The control circuit 1300 may include a current Iout and a voltage Vout sensing circuit for monitoring Iout and Vout, respectively.

In this exemplary embodiment, the control logic separates the module from the output terminal 1370 if the remote switch shorts the power line together or blocks the power line current. Reconnection may be inhibited by an internal load until the remote power source increases the power line voltage. Note that the control logic references the instantaneous values of these variables as well as the time averages of Iout and Vout to implement the detach and reconnect methods described herein.

Embodiments of the present invention provide a circuit known as an optimizer that adjusts the DC-DC conversion so that each module operates at its maximum power point, or more specifically, such that each module operates at its maximum power point. Note that it may also include a circuit known as a micro inverter that regulates the DC-AC conversion.

Embodiments of the present invention may also be combined with a transient fault detector attached to each photovoltaic module. Remote arc fault or ground fault detectors can be used with the devices or methods described herein in combination with remote disconnect or shorting switches and remote reconnect power supplies.

In addition, although simple control logic hardware can be used, other hardware, such as a microcontroller or ASIC (special purpose integrated circuit), can be used instead to implement the basic control logic described herein, which is augmented by more complex signal processing.

14 shows an exemplary state in which a normally open relay switch 1450 and control circuit 1410 and a PV module are coupled to an output terminal in accordance with an embodiment of the present invention.

The control circuit 1410 provides flexibility to predetermine terminal voltage thresholds for closing and opening the switch 1450. The control circuit 1410 latches the relays in the closed and open. If the output terminal is electrically disconnected from an external power source or load, the state of the switch 1450 does not change because the switch is latched.

For example, as shown, an electromechanical relay version of the device with relay switch 1450 that is normally open replaces the FET as described above. Transistor T3 drives the relay coil. Diode D6 prevents the overvoltage from appearing across T3, and diode D5 prevents the excess voltage from appearing between the positive and negative output terminals with the PV panel.

Again, note that the technique described herein is well suited for use in any type of power system. However, it should be understood that embodiments of the present invention are not limited to use in such an application and the techniques described herein are well suited for other applications as well.

While the invention has been shown and described with reference to preferred embodiments, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. will be. Such modifications are intended to be included within the scope of this invention. Accordingly, the foregoing description of the embodiments of the invention is not intended to be limiting. Rather, any limitations to the invention are provided in the claims.

Claims (26)

In the power system,
A string of generator modules connected in series controllably to deliver power generated in the generator module to a load via a power line passing through the generator module, each individual generator module comprising:
A sensing element for monitoring the presence of a control signal received by the individual generator modules via a power line from the remote signal generator;
A switch for selectively connecting the individual generator modules connected in series;
A controller for controlling the state of the switch based on a control signal received through a power line
That includes a power system. The photovoltaic (PV) module of claim 1, wherein the generator module converts solar energy into electrical energy.
Wherein each generator module in the string includes an anode and a cathode connected in series to a power line. The method of claim 1, wherein the control signal is an AC signal generated by the remote signal generator,
Each generator module comprising a capacitor disposed between the output terminals of the individual generator modules to transmit control signals over the power line. The power system of claim 1 wherein the controller sets the switch to the OFF state to operate the individual generator modules in bypass mode when no controller signal is present. The method of claim 1, wherein the sensing element is a current sensing element for detecting a control signal;
The controller activates the switch in an ON state in response to detecting that the current sensed by the current sensing element is greater than a first threshold,
The controller deactivates the switch to an off state in response to detecting that the current sensed by the current sensing element is less than a second threshold. 6. The power system of claim 5, wherein the first threshold and the second threshold are substantially the same value. The power system of claim 1 further comprising a diode disposed between the output terminals of the individual generator modules to protect the switch from damage due to overvoltage conditions. 8. The diode of claim 7, wherein the diode acts as a bypass diode when the switch is set to the off state such that an over-temperature and under-voltage control does not block the string current. The power system to limit the power dissipation of the control circuit in the module. The power system of claim 1 wherein the sensing element is a transformer element that detects the presence of current injected into a power line by the remote signal generator. The method of claim 1 wherein the current through the string is
Short circuit of the output voltage of the string;
Termination of control signal generation;
Disabling the remote signal generator according to a fault condition;
Opening of power line disconnect switch; Physical separation of the generator module from the string; And
Opening of fuse elements or circuit breakers placed between the generator module and the load
And decrease in response to at least one condition from the group consisting of: a. The power system of claim 1, wherein the controller and associated control circuitry in the individual generator module are powered by power generated by a power source in the individual generator module. The power system of claim 1 wherein the switch is a transistor. The power system of claim 1 wherein the switch is an electromechanical relay element. 3. The power system of claim 2, wherein the individual generator module includes a temperature sensor circuit and the controller turns off the switch in response to detecting that the temperature associated with the individual generator module is above a threshold. 3. The power system of claim 2, wherein the individual generator module includes a voltage level sensor that controls the switch to an off state in response to detecting that the voltage generated by the individual generator module is below an undervoltage threshold. The power system of claim 10, wherein the generation of parallel arcs across the array of individual generator modules reduces the array voltage, thereby reducing power that can separate the module from the output array and propagate to a fault. The power system of claim 1 wherein the remote signal generator generates a control signal as a keep-alive signal. Generating a control signal;
Transmitting the control signal via a power line to activate each of a plurality of generator modules having a plurality of generator modules connected in series;
Receiving power over a power line from an activated generator module of a serial connection. 19. The method of claim 18, wherein generating the control signal comprises generating the control signal as an AC signal over a power line,
Receiving power over the power line includes receiving substantially a DC voltage generated by an activated generator module in series connection to power a load. 19. The method of claim 18, further comprising stopping transmission of control signals over a power line to deactivate each individual generator module to which the plurality of generator modules are connected in series. 19. The method of claim 18, wherein the transmission of the control signal over the power line causes substantially simultaneous activation of the generator module to produce an output voltage. In the generator module arranged in series connection of a plurality of generator modules, the individual generator module connected in series,
An anode power terminal;
A cathode power terminal;
A diode element, wherein an anode of the diode element is coupled via an electrical path to a cathode power terminal of an individual generator module and a cathode of the diode element is coupled via an electrical path to an anode power terminal of a generator module. . 23. The apparatus of claim 22, further comprising a switch disposed in series with the power source in the individual generator module that generates power, wherein the switch applies power generated by the power source between the anode power terminal and the cathode power terminal of the individual generator module. Generator module to control the thing. 24. The generator module of claim 23, wherein the switch is a field effect transistor having an inherent diode, and the forward bias of the intrinsic diode supports current flow through the power supply from the anode power terminal to the cathode power terminal. . 25. The generator module of claim 24 wherein the combination of switches arranged in series with the power source is disposed substantially in parallel with the diode element. 24. The method of claim 23,
A sensor element for monitoring a communication signal received via a power line to which the anode power terminal and the cathode power terminal are connected;
Generator module further comprising a control circuit for controlling the state of the switch in accordance with the communication signal.

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