A Modular String Inverter Online Program Upgrade Architecture and Method

Abstract

This application discloses an online program upgrade architecture and method for modular string inverters. The architecture includes a relay control logic unit and multiple controller DSPs. Each string module controls a relay group through at least one controller DSP. The relay control logic unit controls the relay groups connected to the grid and the load. When at least one controller DSP is being upgraded, the controller DSP controls the corresponding string module's relay group to disconnect. The relay logic control unit continues to maintain the relay group closed through communication with the other controller DSPs. The method is implemented using the above architecture. The beneficial effects of this application are: for string module inverter systems, an online program upgrade scheme and an upgrade preparation power redistribution control method are proposed, which can ensure that the grid-side relays remain in the conducting state during the program upgrade process, ensuring the reliability of the load power supply; at the same time, the entire upgrade process can be smoothly switched to minimize AC side power changes.

Description

Technical Field

[0001] This application relates to the field of new energy power generation technology, and in particular to an online program upgrade architecture and method for modular string inverters. Background Technology

[0002] Modular string photovoltaic-storage inverter systems offer advantages such as high flexibility and easy capacity expansion. For example... Figure 1 and Figure 2 As shown, a traditional modular string photovoltaic-storage inverter system mainly consists of multiple string modules connected in parallel to the bus. These modules are connected in parallel and then connected to the grid and load via relay groups relay-G and relay groups relay-L, thus enabling system expansion. Each PV unit of each string module is connected to the DC bus via its own DC / DC unit; the battery is connected to the DC bus via a bidirectional DC / DC unit; and the DC bus outputs power via relay groups after passing through a DC / AC unit. However, existing technologies do not disclose a solution for online program upgrades of modular string photovoltaic-storage inverters that do not result in load power loss. Summary of the Invention

[0003] One objective of this application is to provide an architecture for implementing an online program upgrade method for modular string inverters, which can solve at least one of the deficiencies in the aforementioned background technology.

[0004] To achieve the aforementioned objective, the technical solution adopted in this application is as follows: an online program upgrade architecture for a modular string inverter, the modular string inverter including relay groups connected to each string module, and relay groups relay-G and relay-L connected to the AC side of the bus; the architecture includes a relay control logic unit, multiple controller DSPs, and a host computer ARM; each string module controls the relay groups through at least one of the controller DSPs, and the controller DSPs corresponding to each string module communicate with each other through a communication bus; the relay control logic unit is communicatively connected to each of the controller DSPs, and the relay control logic unit controls the relay groups relay-G and relay-L connected to the power grid and the load; the host computer ARM is adapted to issue upgrade commands to the controller DSPs via communication; when at least one controller DSP is upgraded, the controller DSP controls the corresponding string module to be blocked; the relay control logic unit continues to maintain the closure of relay groups relay-G and relay-L through communication with the other controller DSPs.

[0005] Preferably, each of the serial modules corresponds to multiple controllers (DSPs), and the controllers (DSPs) communicate with each other; all the controllers (DSPs) simultaneously control the relay group of the serial module, so that when one or more of the controllers (DSPs) are upgraded, the relay group of the serial module is disconnected; one of the controllers (DSPs) corresponding to the serial module is connected to the communication bus to receive program upgrade instructions from all the controllers (DSPs) corresponding to the serial module.

[0006] Preferably, the modular string inverter online program upgrade architecture further includes multiple first AND gate units, each corresponding to a string module; the input of the first AND gate unit is communicatively connected to multiple controllers (DSPs) corresponding to the string module, and the output of the first AND gate unit is driven and controlled by the relay group of the string module; when one or more of the controllers (DSPs) corresponding to the string module are upgraded, the first AND gate unit is adapted to output a low-level drive signal to drive the corresponding relay group to disconnect.

[0007] Preferably, the serial module corresponds to two controllers DSPs that communicate with each other, namely DSP#_1 and DSP#_2. DSP#_1 communicates with the communication bus. DSP#_1 is used to control the DC / DC unit and the bidirectional DC / DC unit of the serial module, and DSP#_2 is used to control the DC / AC unit of the serial module. DSP#_1 and DSP#_2 simultaneously control the relay group of the serial module.

[0008] Preferably, the relay control logic unit includes a first OR gate unit, a second OR gate unit, a second AND gate unit, and a third AND gate unit; the first OR gate unit is adapted to receive the control signal relay-G-ctrl issued by DSP#_1 corresponding to each of the serial modules; the second OR gate unit is adapted to receive the control signal relay-L-ctrl issued by DSP#_1 corresponding to each of the serial modules; the second AND gate unit is adapted to receive the output signal of the first OR gate unit and the blocking signal relay_block issued by DSP#_2 corresponding to each of the serial modules; the second AND gate unit is adapted to output the drive signal relay-G_drv for controlling the relay group relay-G; the third AND gate unit is adapted to receive the output signal of the second OR gate unit and the blocking signal relay_block issued by DSP#_2 corresponding to each of the serial modules; the third AND gate unit is adapted to output the drive signal relay-L_drv for controlling the relay group relay-L.

[0009] Preferably, when the controller corresponding to one or more of the string modules is upgraded, the remaining string modules are redistributed through the corresponding controller DSP, so that the output power allocation of the string module corresponding to the controller to be upgraded is 0.

[0010] A method for online program upgrade of a modular string inverter utilizing the above-mentioned modular string inverter online program upgrade architecture includes the following steps: A host computer ARM sends a program upgrade preparation command to the controller DSP to be upgraded; the host computer ARM performs overall power reallocation based on feedback information from the controller DSP to be upgraded, so that the output power of the string module corresponding to the controller DSP to be upgraded is 0; after completing power control, the host computer ARM sends an upgrade program package to the controller DSP to be upgraded; the controller DSP to be upgraded receives the upgrade program package and completes the upgrade after controlling the corresponding relay group to disconnect; after completing the upgrade, the controller DSP reconnects to the grid and feeds back information to the host computer ARM; the host computer ARM issues power allocation values ​​to the corresponding string module based on the information fed back by the controller DSP.

[0011] Preferably, the process of the host computer ARM redistributing the overall power based on the feedback information from the controller DSP to be upgraded is as follows: For the string module to be upgraded, the DC / DC unit limits the power through the MPPT control loop so that the target value of the load power corresponding to the PV unit is reduced to 0; the bidirectional DC / DC unit adopts dual-loop control of power loop and current loop so that the target value of the power loop corresponding to the battery is reduced to 0; the DC / AC unit adopts dual-loop control of voltage loop and current loop to balance the power of the bus voltage.

[0012] Preferably, the information fed back from the controller DSP to the host ARM includes the output power P of the serial module to be upgraded. AC1 and battery power P B1 And the MPPT power P of the non-upgraded string module MPPT2 Output power P AC2 and battery power P B2 Thus, the corresponding load power P is obtained. L When the controller DSP is upgraded, the control logic of the host computer ARM for the non-upgraded serial modules is as follows:

[0013] P B2_ref =P B2_max1 (P) L -P PV1 -P B1 -P MPPT2 >P B2_max1 );

[0014] P B2_ref = P L -P PV1_ref -P B1_ref -P MPPT2 , (-P B2_max2 <P L -P PV1 -P B1 -P MPPT2 <P B2_max1 );

[0015] P B2_ref =P B2_max2 , (P L -P PV1 -P B1 -P MPPT2 <-P B2_max2 );

[0016] Among them, P B2_ref P represents the target power loop value corresponding to the battery in the non-upgraded string module. B2_max1 and P B2_max2P represents the maximum discharge power and maximum charging power of the battery in the non-upgraded string module, respectively. PV1_ref P represents the target load power of the string module to be upgraded. PV1 This indicates the PV unit output power of the string module to be upgraded.

[0017] Preferably, after the controller DSP completes the upgrade, the host computer ARM performs power allocation for the string modules as follows: the DC / AC unit performs dual-loop control of the bus voltage for the upgraded string modules through voltage and current loops; when the bus voltage stabilizes at the target value, the DC / DC unit executes MPPT control to track the maximum power point; when the maximum power point is tracked, the host computer ARM sends the battery power target value to all the string modules according to the current working mode, power information, and battery status, and then controls the battery power through power and current loops.

[0018] Compared with the prior art, the beneficial effects of this application are as follows:

[0019] For string module inverter systems, this application proposes an online program upgrade scheme and an upgrade preparation power redistribution control method. This ensures that the grid-side relays remain on during the program upgrade process, guaranteeing the reliability of the load power supply. Simultaneously, the entire upgrade process features a smooth switching mechanism, minimizing AC side power fluctuations. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall architecture of a modular string photovoltaic-storage inverter according to this application.

[0021] Figure 2 This is a schematic diagram of the topology of a modular string photovoltaic-storage inverter according to this application.

[0022] Figure 3 This is a schematic diagram of the online program upgrade architecture for the modular string inverter in this application.

[0023] Figure 4 This is a schematic diagram of the online program upgrade architecture for a single-module, multi-DSP scenario in this application.

[0024] Figure 5 This is a schematic diagram of the circuit topology of the relay control logic unit in this application.

[0025] Figure 6 This is a schematic diagram of the control loop of each converter in this application.

[0026] Figure 7 This is a schematic diagram illustrating the online upgrade process for DSP#1_1 in this application.

[0027] Figure 8 This is a timing diagram illustrating the online upgrade of DSP#1_1 in this application.

[0028] Figure 9 This is a schematic diagram of the online upgrade process for DSP#1_2 in this application.

[0029] Figure 10 This is a timing diagram illustrating the online upgrade of DSP#1_2 in this application. Detailed Implementation

[0030] The present application will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0031] In the description of this application, it should be noted that the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., which indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and should not be construed as limiting the specific protection scope of this application.

[0032] It should be noted that the terms "first," "second," etc., in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0033] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0034] One aspect of this application provides a modular string inverter online program upgrade architecture, such as Figure 3As shown, one preferred embodiment includes a relay control logic unit and multiple controller DSPs. The modular string inverter includes at least one string module, each string module controlling a relay group via at least one controller DSP. The controller DSPs corresponding to each string module can communicate with each other via a communication bus. The relay control logic unit communicates with all the controller DSPs, and its output can be connected to relay groups relay-G and relay-L connected to the power grid and load. Relay groups relay-G and relay-L are then comprehensively controlled by the controller DSPs corresponding to all string modules.

[0035] When the controller DSP is operating normally, it can output a high-level enable control signal to the corresponding relay group, causing the relay group to close and conduct, thus enabling the string module to connect to the bus. At this time, the relay control logic unit, based on the output signal from the controller DSP, can output high-level enable signals to relay groups relay-G and relay-L, causing both relay groups relay-G and relay-L to close and conduct, thereby achieving grid connection of the string module and normal power supply to the load.

[0036] When one or more controller DSPs are upgraded, these controller DSPs can output control signals to control the corresponding string module to lock down. There are several ways to lock down the module, such as directly disconnecting the relay group to reduce the output power of the string module to 0; or locking down the DC / AC unit of the string module to reduce the output power of the string module to 0, while the relay group remains open. Meanwhile, the relay control logic unit can continue to maintain the closure of relay-G and relay-L through communication with the other controller DSPs, thus ensuring uninterrupted operation of the load.

[0037] It should be understood that the specific structure and working principle of the DSP controller are well-known to those skilled in the art, and therefore will not be described in detail here. Upgrade instructions for the DSP controller can be implemented through a host ARM processor. The host ARM processor communicates with the DSP controller via signal lines, commonly including BOOT, RESET, and communication buses such as CAN. The specific structure and working principle of the host ARM processor are well-known to those skilled in the art, and therefore will not be described in detail here. During normal operation of the DSP controller, the host ARM processor can send high-level signals to the DSP controller via the BOOT and RESET signal lines, causing the DSP controller to output corresponding high-level control signals to control the corresponding relay group to enter a high-level enabled closed state.

[0038] It should also be noted that when the controller DSP is upgraded, its corresponding string module is blocked and unable to output power, which may lead to bus voltage fluctuations. Therefore, during the upgrade of the controller DSP, the output power of the entire modular string inverter can be redistributed through the communication bus interconnecting the various controller DSPs. This allows the output power of the string module corresponding to the controller DSP to be upgraded to be reduced to 0 first, thus ensuring a smooth switching of the controller DSP during the upgrade process and minimizing the impact of AC power changes on the bus voltage.

[0039] It is understandable that a modular string inverter can include N string modules, labeled string module #1 to #N; each string module can correspond to M PV units and DC / DC units. Taking any string module #i as an example, each PV unit and DC / DC unit can be labeled PV#i_1 to PV#i_M, and DC / DC#i_1 to DC / DC#i_M, respectively. The values ​​of N and M can be set according to actual needs, and the values ​​of N and M are generally greater than 1. There are multiple control methods for each string module, which will be analyzed through two specific examples below.

[0040] Specific Example 1: A string module can be controlled by a single DSP controller to manage the corresponding DC / DC unit, bidirectional DC / DC unit, DC / AC unit, and relay group. If the DSP controller needs upgrading, it can first limit the output power of the string module to 0 by controlling each converter, and then output a low-level control signal to the corresponding relay group to disconnect the relay group.

[0041] Specific Example 2: Each string module can control the aforementioned converters through multiple controller DSPs, and these controller DSPs can simultaneously control the relay group. The controller DSPs can communicate with each other via signal lines, such as I2C. One controller DSP communicates with the communication bus, allowing it to receive upgrade commands and upgrade packages from all controller DSPs and transmit them to the other controller DSPs via I2C. Alternatively, all controller DSPs can communicate with the communication bus, allowing them to receive corresponding upgrade commands and upgrade packages. When one or more controller DSPs need upgrading, each controller DSP can first control its corresponding converter to limit the output power of the string module to 0. Then, the controller DSP requiring upgrade, or all controller DSPs, outputs a low-level control signal to the corresponding relay group, disconnecting the relay group.

[0042] It should be noted that both of the above specific examples can meet the needs of this application, and those skilled in the art can choose according to actual needs. In this embodiment, the control of the serial module preferably adopts the above specific example two; and for ease of description, the following content will be described using the example of multiple controller DSPs communicating with the communication bus through only one controller DSP, and the upgraded controller DSP sending a low-level control signal to the relay group.

[0043] In this embodiment, there are multiple control scenarios for the multiple controllers (DSPs) corresponding to the serial module. Each controller (DSP) can control one converter individually, or the controller (DSP) can control multiple converters simultaneously. To improve resource utilization, this embodiment preferably adopts a combination of both methods. For ease of understanding, a specific example will be used to illustrate this in detail below.

[0044] Specifically, such as Figure 4As shown, each string module corresponds to two DSP controllers, which can be labeled DSP#_1 and DSP#_2 respectively. DSP#_1 can communicate with the communication bus, while DSP#_2 communicates with DSP#_1 via signal lines. DSP#_1 controls all DC / DC units and bidirectional DC / DC units of the string module, while DSP#_2 controls the DC / AC units. Both DSP#_1 and DSP#_2 simultaneously control the relay group of the string module. It should be noted that the DC / AC units need to process data from multiple DC / DC units and bidirectional DC / AC units simultaneously, therefore a separate DSP controller can be used for control. Since the data processing volume of a single DC / DC unit is relatively small, a separate DSP controller can be used to simultaneously control all DC / DC units and bidirectional DC / DC units.

[0045] In this embodiment, there are various specific structures for the multiple controllers (DSPs) corresponding to the serial module to control the relay group. For ease of understanding, one of these structures will be described in detail below. Figure 4 As shown, the modular string inverter online program upgrade architecture also includes multiple first AND gate units, each corresponding to a string module. The input of the first AND gate unit can communicate with multiple DSP controllers corresponding to the string module, and the output of the first AND gate unit drives and controls the relay group of the string module. When one or more DSP controllers corresponding to the string module are being upgraded, a low-level control signal can be sent to the first AND gate unit; thus, the first AND gate unit can output a low-level drive signal relay_drv according to its own working logic to drive the corresponding relay group to disconnect.

[0046] It should be noted that the specific structure and working principle of the first AND gate unit are well-known to those skilled in the art, and therefore will not be described in detail here; the working logic of the AND gate unit is that it only outputs a high level when all input terminals are high level.

[0047] In this embodiment, there are various specific structures for the relay control logic unit that can ensure uninterrupted power supply to the output relay groups relay-G and relay-L during DSP controller upgrades. For ease of understanding, one such structure will be described in detail below. Figure 4 and Figure 5 As shown, the relay control logic unit includes a first OR gate unit, a second OR gate unit, a second AND gate unit, and a third AND gate unit.

[0048] The input terminal of the first OR gate unit is connected to the DSP#_1 corresponding to each group of serial modules, and the output terminal of the first OR gate unit is connected to one of the input terminals of the second AND gate unit. Thus, the first OR gate unit can receive the control signal relay-G-ctrl sent by the DSP#_1 corresponding to each group of serial modules and send the corresponding level signal to the second AND gate unit.

[0049] The input terminal of the second OR gate unit is connected to the DSP#_1 corresponding to each group of serial modules, and the output terminal of the first OR gate unit is connected to one of the input terminals of the third AND gate unit. Thus, the first OR gate unit can receive the control signal relay-L-ctrl sent by the DSP#_1 corresponding to each group of serial modules and send the corresponding level signal to the third AND gate unit.

[0050] The remaining inputs of the second AND gate unit are connected to the controller DSP#2 corresponding to each group of serial modules for communication. The output of the second AND gate unit is connected to the relay group relay-G for control. Thus, the second AND gate unit can output the drive signal relay-G_drv to control the relay group relay-G based on the level signal received from the first OR gate unit and the blocking signal relay_block issued by the DSP#_2 corresponding to each group of serial modules.

[0051] The remaining inputs of the third AND gate unit are connected to the controller DSP#2 corresponding to each of the serial modules, and the output of the third AND gate unit is connected to the relay group relay-L for control. Therefore, the third AND gate unit can output a drive signal relay-L_drv to control the relay group relay-L based on the level signal received from the second OR gate unit and the blocking signal relay_block issued by the DSP#_2 corresponding to each serial module.

[0052] It should be understood that the specific structure and working principle of the first OR gate, the second OR gate, the third AND gate, and the fourth AND gate are well-known technologies to those skilled in the art, and therefore will not be described in detail here; the working logic of the OR gate is that it outputs a low level only when all inputs are low level, and the working logic of the AND gate is that it outputs a high level only when all inputs are high level.

[0053] For ease of understanding, the following will describe in detail the specific working process of the modular string inverter online upgrade architecture of this application, taking an example where both N and M are 2.

[0054] like Figure 4 and Figure 5As shown, the two DSP controllers corresponding to string module #1 can be labeled as DSP#1_1 and DSP#1_2, respectively, and the two DSP controllers corresponding to string module #2 can be labeled as DSP#2_1 and DSP#2_2, respectively. The communication buses include CANH and CANL. The host computer ARM communicates with the CANH and CANL communication buses via communication lines CAN_RX and CAN_TX, respectively. DSP#1_1 communicates with the CANH and CANL communication buses via communication lines CAN_RX_1 and CAN_TX_1, respectively, and DSP#2_1 communicates with the CANH and CANL communication buses via communication lines CAN_RX_2 and CAN_TX_2, respectively. The host computer ARM communicates with DSP#1_1 and DSP#2_1 via upgrade signal lines RESET1 and RESET2, respectively, and also communicates with DSP#1_1 and DSP#2_1 simultaneously via the upgrade signal line BOOT. DSP#1_1 communicates with DSP#1_2 via communication lines SCL_1 and SLA_1, and also via upgrade signal lines BOOT1_2 and RESET1_2. DSP#2_1 communicates with DSP#2_2 via communication lines SCL_2 and SLA_2, and also via upgrade signal lines BOOT2_2 and RESET2_2.

[0055] It is important to note that the program upgrade signal lines for DSP#1_1 and DSP#2_1 share a single BOOT line. Reset is performed by the RESET1 and RESET2 lines respectively, determining whether DSP#1_1 or DSP#1_2 will execute the upgrade bootloader based on the BOOT state. The RESET1 and RESET2 lines must not output a low level simultaneously.

[0056] The first AND gate unit corresponding to the serial module #1 can be labeled as AND gate unit #1, and the first AND gate unit corresponding to the serial module #2 can be labeled as AND gate unit #2; the first OR gate unit and the second OR gate unit of the relay control logic unit can be labeled as OR gate unit #1 and OR gate unit #2 respectively; the second AND gate unit and the third AND gate unit of the relay control logic unit can be labeled as AND gate unit #G and AND gate unit #L respectively. AND gate unit #1 sends a drive signal relay1_drv to the relay group relay1 corresponding to the serial module #1 based on the control signal relay1_ctrl received from DSP #1_1 and the blocking signal relay_block_1 received from DSP #1_2. AND gate unit #2 sends a drive signal relay2_drv to the relay group relay2 corresponding to the serial module #2 based on the control signal relay2_ctrl received from DSP #2_1 and the blocking signal relay_block_2 received from DSP #2_2. OR gate unit #1 outputs the corresponding level signal G based on the control signals relay-G_ctrl_1 and relay-G_ctrl_2 received from DSP #1_1 and DSP #2_1, respectively. OR gate unit #2 outputs the corresponding level signal L based on the control signals relay-L_ctrl_1 and relay-L_ctrl_2 received from DSP #1_1 and DSP #2_1, respectively. AND gate unit #G sends a drive signal relay-G_drv to relay group relay-G based on the received level signal G, the blocking signal relay_block_1 sent by DSP #2_1, and the blocking signal relay_block_2 sent by DSP #2_2, respectively. AND gate unit #L sends a drive signal relay-L_drv to relay group relay-L based on the received level signal L, the blocking signal relay_block_1 sent by DSP #2_1, and the blocking signal relay_block_2 sent by DSP #2_2, respectively.

[0057] Based on the example structure above, the working logic relationship of each driving signal can be summarized as follows:

[0058] relay1_drv=relay1_ctrl&relay_block_1.

[0059] relay2_drv=relay2_ctrl&relay_block_2.

[0060] relay-G_drv=(relay-G_ctrl_1|relay-G_ctrl_2)&relay_block_1&relay_block_2.

[0061] relay-L_drv=(relay-L_ctrl_1|relay-L_ctrl_2)&relay_block_1&relay_block_2.

[0062] Another aspect of this application provides a method for online program upgrade of a modular string inverter utilizing the above-described modular string inverter online program upgrade architecture, such as... Figures 7 to 10 As shown, one preferred embodiment includes the following steps: The host computer ARM sends a program upgrade preparation command to the controller DSP to be upgraded. The host computer ARM performs overall power redistribution based on feedback information from the controller DSP to be upgraded, so that the output power of the string module corresponding to the controller DSP to be upgraded is 0. After completing power control, the host computer ARM sends an upgrade program package to the controller DSP to be upgraded. The controller DSP to be upgraded receives the upgrade program package and completes the upgrade after controlling the corresponding relay group to disconnect. After completing the upgrade, the controller DSP reconnects to the grid and feeds back information to the host computer ARM. The host computer ARM then issues power allocation values ​​to the corresponding string module based on the information fed back by the controller DSP.

[0063] It is understandable that the DSP controller program upgrade process can be divided into a preparation phase, an upgrade phase, and an upgrade completion phase. For ease of understanding, the upgrade process can be described in detail below using the aforementioned architecture topology where both N and M are 2. Since the upgrade process for DSP#2_1 is the same as that for DSP#1_1, and the upgrade process for DSP#2_2 is the same as that for DSP#1_2, the following content only describes the upgrade process for DSP#1_1 and DSP#1_2. For ease of description, the string module corresponding to the DSP controller to be upgraded can be defined as the string module to be upgraded, and the remaining string modules can be defined as non-upgraded string modules.

[0064] I. The upgrade process of DSP#1_1, as follows: Figure 3 , Figure 4 , Figure 7 and Figure 8 As shown.

[0065] Preparation Phase: First, the host computer ARM sends program upgrade preparation instructions for DSP#1_1 to DSP#1_1 and DSP#2_1, corresponding to... Figure 8When positions a1 and a2 are reached, the modular string inverter enters the preparation stage. After receiving the program upgrade command, DSP#1_1 and DSP#2_1 send the output power P of the string module #1 to be upgraded to the host ARM computer. AC1 and battery power P B1 And the MPPT power P of the non-upgraded string module #2 MPPT2 Output power P AC2 and battery power P B2 ,correspond Figure 8 Positions b1 and b2 are used to obtain the load power P from the host ARM processor. L .

[0066] Then, the modular string inverter enters the power redistribution control phase of the upgrade preparation stage. The host ARM processor performs power allocation based on the overall power information of the current modular string inverter, corresponding to... Figure 8 Positions a3 and a4 are adjusted to ensure that the output power P of the string module #1 to be upgraded is... AC1 The value is 0. The specific control process is as follows:

[0067] like Figure 6 As shown, for the string module #1 to be upgraded, its DC / DC unit can be power limited by the MPPT control loop so that the target load power P corresponding to the PV unit can be limited. PV1_ref The voltage is reduced to 0 at a certain slope. The bidirectional DC / DC unit uses a power loop and a current loop to perform dual-loop control of the battery power, so that the target value P of the power loop corresponding to the battery is achieved. B1_ref The absolute value is reduced to 0 with a certain slope. The DC / AC unit uses a voltage loop and a current loop to perform dual-loop control of the bus voltage, thereby achieving power balance.

[0068] For the non-upgraded string module #2, its DC / DC unit uses MPPT control; the bidirectional DC / DC unit uses dual-loop control of power loop and current loop, with a target power loop value P. B2_ref The host ARM processor sets the target battery power value based on the current operating mode, power information, and battery status information of the modular string inverter. The DC / AC unit uses a dual-loop control system (voltage loop and current loop) to manage the bus voltage, thereby achieving power balance. For ease of understanding, the following section will explain in detail the logic for setting the target battery power value of the non-upgraded string module #2, taking the modular string inverter operating in self-consumption mode as an example. The logic for other modes can be adjusted accordingly.

[0069] P B2_ref =P B2_max1 , (P L -P PV1 -PB1 -P MPPT2 >P B2_max1 ).

[0070] P B2_ref = P L -P PV1_ref -P B1_ref -P MPPT2 , (-P B2_max2 <P L -P PV1 -P B1 -P MPPT2 <P B2_max1 ).

[0071] P B2_ref =P B2_max2 , (P L -P PV1 -P B1 -P MPPT2 <-P B2_max2 ).

[0072] Among them, P B2_max1 and P B2_max2 These represent the maximum discharge power and maximum charging power of the battery in a non-upgraded string module, respectively; P PV1 This indicates the PV unit output power of the string module to be upgraded. When P L -P PV1 -P B1 -P MPPT2 >P B2_max1 When P..., it indicates a heavy load, requiring the modular string inverter to output at maximum power, with any shortfall requiring grid power. L -P PV1 -P B1 -P MPPT2 <-P B2_max2 When -P indicates a very light load, the PV unit can fully charge the battery, with the excess power fed into the grid. B2_max2 <P L -P PV1 -P B1 -P MPPT2 <P B2_max1 This indicates that the modular string inverter can meet the self-generation and self-consumption requirements, and the power fed into the grid is 0.

[0073] It should be noted that if the above scheme is extended to two or more string module schemes, the power control loop is the same, and the host computer ARM only needs to adjust the target battery power value of each string module according to the system power information and battery status information.

[0074] After the system loop control of the modular string inverter, if the output power of the string module #1 to be upgraded is adjusted to 0, the drive signals of each converter in the string module #1 to be upgraded are blocked. Then, DSP #1_1 sends power control completion information to the ARM, corresponding to... Figure 8 Position b3; then DSP#1_1 begins the upgrade phase. If the output power of the string module #1 to be upgraded is not adjusted to 0, power control continues.

[0075] Upgrade Phase: The host ARM processor first sets the BOOT and RESET1 lines to low level. Specifically, the RESET1 line can be set to low level 10ms later than the BOOT line. That is, the host ARM processor sets the BOOT line to low level first, and then sets the RESET1 line to low level 10ms later. This pulls the control signals relay1_ctrl, relay-G_ctrl_1, and relay-L_ctrl_1 down to low level. At this time, the RESET2 line remains high, and the control signals relay2_ctrl, relay-G_ctrl_2, and relay-L_ctrl_2 remain high. After the logic unit operates, the output drive signal relay1_drv is low, while drive signals relay2_drv, relay-G_drv, and relay-L_drv are high. This disconnects relay group relay1 corresponding to the upgraded string module #1, while relays relay2, relay-G, and relay-L remain on, ensuring the load continues to operate without power loss. After the RESET1 line resets, DSP#1_1 executes the bootloader, begins receiving the upgrade package, and performs the upgrade. Figure 8 Position a5. After the upgrade package is received, the upgrade completion phase begins. It should be noted that during the upgrade phase, DSP#1_2 maintains normal operation and communication; simultaneously, the non-upgraded string module #2 continues to maintain the power redistribution control from the upgrade preparation phase. Specifically, during the DSP#1_1 upgrade process, DSP#2_1 communicates normally with the host ARM, and DSP#2_1 operates normally. The relay groups relay2, relay-G, and relay-L are maintained and controlled by DSP#2_1. Furthermore, when DSP#1_1 is reset, the signal on the RESET1_2 line needs to be pulled up to ensure DSP#1_2 operates normally and guarantees the normal output of the blocking signal relay_block_1.

[0076] Upgrade Completion Phase: The host ARM processor sets the BOOT line, control signals relay-G_ctrl_1, and relay-L_ctrl_1 to high level to restore communication between DSP#1_1 and the host ARM processor. Simultaneously, the upgraded string module #1 is connected to the grid. After string module #1 is connected to the grid, the control signal relay1_ctrl is set to high level, causing the DC / AC and DC / DC units of string module #1 to resume power control. Then, DSP#1_1 and DSP#1_2 respectively send the current power and battery status information of string modules #1 and #2 to the host ARM processor. Figure 8 Positions b4 and b5 are specified. Then, the host ARM computer sends power control commands, i.e., the target battery power values, to DSP#1_1 and DSP#1_2 respectively for serial module #1 and serial module #2. Figure 8 Positions a6 and a7 are then selected; subsequently, the modular string inverter begins normal operation. The target battery power value is given by the host computer ARM based on the set operating mode, the overall power of the modular string inverter, and the battery status.

[0077] The specific power control of the string module by the host computer ARM includes the following process: First, for the upgraded string module #1, the DC / AC unit performs dual-loop control of the bus voltage through voltage and current loops. Once the bus voltage stabilizes at the target value, the DC / DC unit executes MPPT control to track the maximum power point. At this time, the PV unit of string module #1 feeds energy into the grid. After tracking the maximum power point, the host computer ARM, based on the current operating mode (e.g., self-consumption mode), power information, and battery status information, sends the battery power target value to the upgraded string module #1 and the non-upgraded string module #2, controlling the battery power through dual-loop control of the power and current loops. During this stage, the DC / DC unit of the non-upgraded string module #2 executes MPPT control, and the DC / AC unit controls the bus voltage and achieves power balance through dual-loop control of the voltage and current loops.

[0078] I. The upgrade process of DSP#1_2, as follows: Figure 3 , Figure 4 , Figure 9 and Figure 10 As shown.

[0079] The upgrade of DSP#1_2, controlled by DSP#1_1, can be divided into a preparation phase, an upgrade phase, and an upgrade completion phase. The upgrade preparation phase is the same as that of DSP#1_1, and therefore will not be repeated here. The upgrade and completion phases of the DSP#1_2 upgrade process will be described in detail below. Figure 10The positions corresponding to c1 to c4 in the middle Figure 8 Positions a1 to a4 in the text, Figure 10 The positions d1 to d3 in the middle correspond to Figure 8 Positions b1 to b3 in the diagram.

[0080] Upgrade Phase: The host ARM computer sends the upgrade package for DSP#1_2 to DSP#1_1 via the CAN bus. Figure 10 In position c5; after receiving and storing the upgrade package, DSP#1_1 first sets the BOOT1_2 line to low level, and then sets the RESET1_2 line to low level after 10ms. Then, DSP#1_2 receives the upgrade package via I2C communication. Figure 10 Position e5. During the upgrade process, the blocking signal relay_block_1 output by DSP#1_2 is reset and pulled up to a high level, losing its blocking function; it should be noted that the blocking signal relay_block_1 is reset and pulled up through external hardware. At this time, the control signals relay1_ctrl, relay-G_ctrl_1, and relay-L_ctrl_1 output by DSP#1_1 remain at a high level; the control signals relay2_ctrl, relay-G_ctrl_2, and relay-L_ctrl_2 output by DSP#2_1 also remain at a high level. Therefore, after each logic unit performs its logic operation, the output drive signals relay1_drv, relay2_drv, relay-G_drv, and relay-L_drv are all at a high level, and the relay groups relay1, relay2, relay-G, and relay-L all remain in the on state. It should be noted that during the program upgrade phase, although relay group relay1 remains on, the DC / AC circuit controlled by DSP#1_2 stops working. Therefore, the string module #1 still cannot output power, i.e., the output power is 0.

[0081] Upgrade Completion Phase: After DSP#1_2 completes the upgrade, the host ARM can set the BOOT line, control signals relay-G_ctrl_1, and relay-L_ctrl_1 to high level. DSP#1_1 resumes communication with the host ARM. Once the string module #1 is reconnected to the grid, the control signal relay1_ctrl is set to high level, and the DC / AC and DC / DC units of the string module #1 begin to resume power control; at this time, the output power P of the string module #1... AC1 This refers to the MPPT power tracked by the DC / DC unit. Once the DC / DC unit tracks the maximum power, DSP#1_1 resumes communication with the host ARM and sends the current power and battery status information of the string module #1 to the host ARM. Figure 10 At position d4; DSP#2_1 sends the current power and battery status information of the serial module #2 to the host ARM, corresponding to... Figure 10 The middle d5 position. Then the host computer ARM sends the target battery power values ​​of string module #1 and string module #2 to DSP#1_1 and DSP#2_1 respectively, corresponding to... Figure 10 Positions C6 and C7 are specified. Subsequently, the modular string inverter begins normal operation, with the battery power target value determined by the host ARM based on the set operating mode, the overall power of the modular string inverter, and the battery status. The power recovery process and control loop at this stage are the same as those at the DSP#1_1 upgrade completion stage, and therefore will not be repeated here.

[0082] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

1. An online program upgrade architecture for a modular string inverter, the modular string inverter comprising a relay set relay connected to each string module, and a relay set relay-G and relay-L connected to an AC side of a bus; characterized by, Comprise: a plurality of controller DSPs; each group string module is controlled by at least one of the controller DSPs, and each of the controller DSPs corresponding to the group string module communicates with each other through a communication bus; a relay control logic unit, which is in communication connection with each of the controller DSPs, and controls the relay group relay-G and relay-L; and a host computer ARM, which is adapted to issue an upgrade instruction to the controller DSP through communication; when at least one of the controller DSPs is upgraded, the controller DSP controls the corresponding group string module to be locked; the relay control logic unit continues to maintain the closure of the relay group relay-G and relay-L through the communication of the remaining controller DSPs; the group string module corresponds to two controller DSPs in communication with each other, namely DSP#_1 and DSP#_2; DSP#_1 is used to control the DC / DC unit and the bidirectional DC / DC unit of the group string module, and DSP#_2 is used to control the DC / AC unit of the group string module; DSP#_1 communicates with the communication bus to receive the program upgrade instruction of all the controller DSPs corresponding to the group string module; DSP#_1 and DSP#_2 simultaneously control the relay group relay of the group string module, so that when one or both of the controller DSPs are upgraded, the relay group relay corresponding to the group string module is disconnected.

2. The modular string inverter online program upgrade architecture of claim 1, wherein, The online program upgrade architecture of the modular group string inverter further comprises a plurality of first AND gate units corresponding to each of the group string modules; the input end of the first AND gate unit is in communication connection with a plurality of the controller DSPs corresponding to the group string module, and the output end of the first AND gate unit drives and controls the relay group relay of the group string module; when one or more of the controller DSPs corresponding to the group string module are upgraded, the first AND gate unit is adapted to output a low-level drive signal to drive the corresponding relay group relay to be disconnected.

3. The modular string inverter online program upgrade architecture of claim 1, wherein, The relay control logic unit comprises: a first OR gate unit, which is adapted to receive the control signal relay-G-ctrl sent by DSP#_1 corresponding to each of the group string modules; a second OR gate unit, which is adapted to receive the control signal relay-L-ctrl sent by DSP#_1 corresponding to each of the group string modules; a second AND gate unit, which is adapted to receive the output signal of the first OR gate unit and the lock signal relay_block sent by DSP#_2 corresponding to each of the group string modules, and is adapted to output the drive signal relay-G_drv for controlling the relay group relay-G; and A third AND gate unit is adapted to receive the output signal of the second OR gate unit and the blocking signal relay_block sent by the corresponding DSP#_2 of each string module, and the second AND gate unit is adapted to output a driving signal relay-L_drv for controlling the relay group relay-L.

4. The modular string inverter online program upgrade architecture of any of claims 1-3, wherein, When one or more of the controllers corresponding to the string modules are upgraded, the remaining string modules perform power redistribution to the corresponding controllers DSP, so that the output power of the string modules corresponding to the controller to be upgraded is 0.

5. A method for online upgrading of the program of a modular string inverter using the online program upgrade architecture of the modular string inverter according to any one of claims 1-4, characterized in that, The method comprises the following steps: The host computer ARM sends a program upgrade preparation instruction to the controller DSP to be upgraded; The host computer ARM performs overall power redistribution according to the feedback information of the controller DSP to be upgraded, so that the output power of the string module corresponding to the controller DSP to be upgraded is 0; After completing the power control, the host computer ARM sends an upgrade program package to the controller DSP to be upgraded, and the controller DSP to be upgraded receives the upgrade program package and completes the upgrade after controlling the corresponding relay group relay to be disconnected; After completing the upgrade, the controller DSP re-connects to the grid and feeds back information to the host computer ARM, and the host computer ARM sends a power distribution value to the corresponding string module according to the feedback information of the controller DSP.

6. The method of claim 5, wherein the module string inverter program is upgraded online. The process of the host computer ARM performing overall power redistribution according to the feedback information of the controller DSP to be upgraded is as follows: For the string module to be upgraded, the DC / DC unit performs power limitation through the MPPT control loop, so that the output power of the PV unit is reduced to 0; The bidirectional DC / DC unit adopts double-loop control of power loop and current loop to reduce the output power of the battery to 0; The DC / AC unit adopts double-loop control of voltage loop and current loop for power balance of the bus voltage.

7. The method of claim 6, wherein the module string inverter program is upgraded online. The information fed back by the controller DSP to be upgraded to the host computer ARM includes output power P of the group string module to be upgraded AC1 and battery power P B1 , and MPPT power P MPPT2 , output power P AC2 and battery power P B2 of the non-upgraded group string module, so as to obtain corresponding load power P L ; When the controller DSP is upgraded, the control logic of the host computer ARM for the non-upgraded string module is as follows: P B2_ref =P B2_max1 , (P L -P PV1 -P B1 -P MPPT2 > P B2_max1 ); P B2_ref = P L -P PV1_ref -P B1_ref -P MPPT2 , (-P B2_max2 <P L -P PV1 -P B1 -P MPPT2 <P B2_max1 ) P B2_ref =P B2_max2 , (P L -P PV1 -P B1 -P MPPT2 <-P B2_max2 ); wherein P B2_ref represents the power loop target value corresponding to the battery in the non-upgraded group string module, P B2_max1 and P B2_max2 respectively represent the maximum discharging power and the maximum charging power of the battery in the non-upgraded group string module, P PV1_ref represents the load limiting power target value of the group string module to be upgraded, P PV1 represents the output power of the PV unit of the group string module to be upgraded.

8. The method of claim 5, wherein the module string inverter program is upgraded online. After the controller DSP completes the upgrade, the host computer ARM performs power distribution for the string module as follows: The completed string module is controlled by the DC / AC unit through the voltage loop and the current loop for the bus voltage; When the bus voltage stabilizes at the target value, the DC / DC unit performs MPPT control to track the maximum power point; When the maximum power point is tracked, the host computer ARM sends a battery power target value to all string modules according to the current working mode, power information and battery state, and then controls the battery power through the power loop and the current loop.

Images