Modular dc power supply battery performance on-line evaluation device and method

Abstract

The application discloses a device and a method for on-line evaluation of performance of a modularized direct-current power supply battery. The modularized direct-current power supply comprises a direct-current bus, a direct-current power supply monitor, power supply modules and alternating current input. A plurality of power supply modules M1-Mn are connected in parallel on the direct-current bus. Each power supply module comprises a charger BC, a battery pack BAT, contactors KM (2n-1) and KM2n, a direct-current circuit breaker QFn capable of being operated under voltage, diodes Dn and a battery evaluation control contactor Kn. n is the number of the power supply module. The direct-current power supply monitor controls cooperation between the direct-current circuit breaker QFn capable of being operated under voltage, the contactors KM (2n-1) and KM2n and the battery evaluation control contactor Kn of each power supply module, and changes the conversion of the charger BC between an AC / DC rectification mode and a DC / DC boost mode. When the charger BC is in the DC / DC boost mode, the battery is evaluated on-line by monitoring the discharge current curve of the battery pack BAT in the current power supply module. Based on the DC / DC boost mode of the series-connected charger, the on-line evaluation of performance of the modularized intelligent direct-current power supply battery is realized, and the method is simple, fast, energy-saving and environment-friendly.

Description

Technical Field

[0001] This invention relates to the field of DC system battery technology, specifically to an online performance evaluation device and method for modular DC power supply batteries. Background Technology

[0002] In a conventional DC power supply system, the charger and battery are connected in parallel to the DC bus. When the AC power is normal, the charger rectifies the AC power into DC power to supply DC loads. Once the AC power fails, the battery bank provides working power to the DC loads. Therefore, ensuring the good performance of the battery is crucial for the safe and reliable power supply of the DC power supply. Currently, the main method for testing the battery performance and remaining capacity of DC power supply systems is to use periodic verification capacity tests. This method is accurate and reliable, but its disadvantages are also obvious: it requires manual on-site operation, a lot of manpower and resources, and there is also a downtime.

[0003] Furthermore, in DC systems where batteries are connected in series as backup power, if the charger loses power or malfunctions and cannot supply power to the DC bus, an open circuit in any one battery could cause the entire DC bus to lose voltage. To overcome the inherent defects of conventional DC power supply batteries operating in series, a parallel DC power supply system with "DC / DC boost" is proposed. Due to the current-limiting characteristics of the boost module, a short-circuit fault can prevent the DC circuit breaker from instantly clearing the fault, leading to a significant drop in DC bus voltage or even a loss of voltage.

[0004] Therefore, how to overcome the shortcomings of conventional DC power supply battery performance monitoring methods, the impact of a single open circuit on the power supply of the entire battery pack in series operation mode, and the low impact capability of parallel DC power supplies, and how to improve the testing efficiency of battery performance are technical problems that urgently need to be solved by those skilled in the art. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a device and method for online evaluation of the performance of modular DC power supply batteries, and to provide a highly safe modular DC power supply and its battery performance online evaluation method.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] The modular DC power supply battery performance online evaluation device includes a DC bus, a DC power supply monitor, power modules and an AC input. Power modules M1 to Mn are connected in parallel on the DC bus. The AC input terminals of all power modules are connected in parallel to the AC input. The DC output terminals of all power modules are connected in parallel on the DC bus. The DC power supply monitor is communicatively connected to all power modules.

[0008] Each power module includes a charger BC, a battery pack BAT, contactors KM(2n-1) and KM2n, a energized DC circuit breaker QFn, a diode Dn, and a battery evaluation control contactor Kn, where n is the power module number. Each power module controls the coordination between the energized DC circuit breaker QFn, contactors KM(2n-1), KM2n, and battery evaluation control contactor Kn through a DC power monitor, changing the charger BC between AC / DC rectification mode and DC / DC boost mode. When the charger BC is in DC / DC boost mode, the battery is evaluated online by monitoring the discharge current curve of the battery pack BAT in the current power module.

[0009] The aforementioned charger BC has two operating modes, specifically:

[0010] In AC / DC rectification mode, the AC input terminal receives AC power and outputs constant voltage DC power to the DC bus.

[0011] In DC / DC boost mode, the DC input terminal receives the DC power from the battery pack BAT, boosts it, and then outputs a constant voltage and constant current DC power to the DC bus.

[0012] The internal structure of the power module described above is as follows:

[0013] The AC input is connected to the normally closed input terminal of KM2n, and the normally closed output terminal of KM2n is connected to the AC input terminal of the charger BC. The DC output terminal of the charger BC is connected to the positive and negative terminals of the battery pack BAT via the normally open contact of contactor KM(2n-1), and to the lower end of the energized DC circuit breaker QFn. The upper end of the energized DC circuit breaker QFn is connected to the DC bus. The positive and negative terminals of the battery pack BAT are connected to the lower end of the energized DC circuit breaker QF1 via the battery evaluation control contactor Kn and diode Dn, and to the normally open input terminal of contactor KM2. The normally open output terminal of contactor KM2 is connected to the DC input terminal of the charger BC.

[0014] The aforementioned diode Dn utilizes its unidirectional conductivity to ensure that the battery pack BAT can only supply power to the DC bus, while the DC bus cannot charge the battery BAT.

[0015] The aforementioned DC power supply monitor communicates with all power modules via an RS485 communication bus.

[0016] The online evaluation method using the above-mentioned modular DC power supply and its battery performance online evaluation device includes the following steps:

[0017] Step 1: When the modular DC power supply is running normally, all contactors KM2n of all power modules M1 to Mn are switched to AC 220V input. That is, the normally closed switch of KM2n remains closed, the normally open switch of KM2n remains open, the internal energized DC circuit breaker QFn is in the closed state, the battery evaluation control contactor Kn is in the closed state, the charger BC converts AC power to DC power in AC / DC rectification mode to supply power to the DC bus, the contactor KM(2n-1) is in the open state, and the battery pack BAT provides hot standby to the DC bus through diode Dn. When the AC input is lost, the battery pack BAT provides uninterrupted power to the DC bus through diode Dn to ensure the reliability of DC power supply.

[0018] Step 2: When it is necessary to evaluate the battery performance of any power module online, assuming that the battery performance of the power module numbered Mn is evaluated online, the DC power monitor controls the contactor KM(2n-1) in the power module to be in the open state, controls the battery evaluation control contactor Kn to be open, and controls contactor KM2n to switch the input of the charger BC from AC input to the input of the battery pack BAT. The battery pack BAT supplies power to the DC bus through the charger BC of this power module in DC / DC boost mode. The charger BC is controlled to adjust the discharge current of the battery pack BAT. By comparing the discharge curve of the normal battery, the performance and load capacity of the battery BAT are evaluated online. The part of insufficient power supply is converted from AC to DC by the charger BC of other power modules in the rectification mode and supplied to the DC bus in a balanced manner.

[0019] Step 3: After the battery pack completes its performance evaluation, the DC power monitor switches the contactor KM2n from the battery pack BAT input to the AC input, controls the energized DC circuit breaker QFn to be in the open state, disconnecting this module from the DC bus. At the same time, it controls the contactor KM(2n-1) to close, and keeps the battery evaluation control contactor Kn open. The charger BC uses AC / DC rectification to convert AC power to DC power to charge the battery pack BAT. The energized DC circuit breakers QFx inside other power modules are in the closed state to supply power to the DC bus, so as to ensure constant current and voltage limiting charging of the battery pack BAT and constant DC bus voltage.

[0020] Step 4: After the battery pack is fully charged, the DC power monitor controls the contactor KM1 (2n-1) in the power module to open, the live DC circuit breaker QFn to close, and the battery evaluation control contactor Kn to close, restoring the power module to normal operation.

[0021] Step 5: Following the steps from Step 1 to Step 4, after completing the online evaluation of the battery pack BAT performance in the power module, the entire modular DC power supply system returns to normal operation.

[0022] The present invention provides a modular DC power supply battery performance online evaluation device and method, which has the following beneficial effects:

[0023] (1) The new modular intelligent DC power supply system adopts a multi-power module bridging power supply method, which completely innovates the DC power supply system structure mode and completely eliminates the serious hidden danger of DC bus voltage loss caused by the entire group of batteries being disconnected from the bus or individual lagging batteries being open-circuited or failing.

[0024] (2) It solves the inherent design defect that the feeder short circuit fault of the "DC / DC boost mode" parallel DC power supply system cannot be automatically cleared, and significantly improves the operational safety of the DC power supply system.

[0025] (3) Based on the DC / DC boost mode of the series charger, the performance of modular intelligent DC power supply batteries can be evaluated online, which is simple, fast, energy-saving and environmentally friendly. Attached Figure Description

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0027] Figure 1 This is a simplified electrical schematic diagram of the modular DC power supply of the present invention;

[0028] Figure 2 Flowchart for online performance evaluation of modular DC power supply batteries.

[0029] In the diagram: DC bus 1, DC power supply monitor 2, power supply module 3, AC input 4. Detailed Implementation

[0030] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0031] A modular DC power supply battery performance online evaluation device, the modular DC power supply includes a DC bus 1, a DC power supply monitor 2, power modules 3 and an AC input 4, power modules 3M1 to 3Mn are connected in parallel on the DC bus 1, the AC input terminals of all power modules 3 are connected in parallel to the AC input 4, the DC output terminals of all power modules 3 are connected in parallel to the DC bus 1, and the DC power supply monitor 2 is communicatively connected to all power modules 3.

[0032] Each power module 3 includes a charger BC, a battery pack BAT, contactors KM(2n-1) and KM2n, a energized DC circuit breaker QFn, a diode Dn, and a battery evaluation control contactor Kn, where n is the number of the power module 3. Each power module 3 controls the coordination between the energized DC circuit breaker QFn, contactors KM(2n-1), KM2n, and battery evaluation control contactor Kn through a DC power monitor 2, changing the switching of the charger BC between AC / DC rectification mode and DC / DC boost mode. When the charger BC is in DC / DC boost mode, the battery is evaluated online by monitoring the discharge current curve of the battery pack BAT in the current power module 3.

[0033] The aforementioned charger BC has two operating modes, specifically:

[0034] In AC / DC rectification mode, the AC input terminal receives the AC power from AC input 4 and outputs a constant voltage DC power to DC bus 1.

[0035] In DC / DC boost mode, the DC input terminal receives the DC power from the battery pack BAT, boosts it, and then outputs a constant voltage and constant current DC power to DC bus 1.

[0036] The internal structure of the power module 3 described above is as follows:

[0037] AC input 4 is connected to the normally closed input terminal of KM2n. The normally closed output terminal of KM2n is connected to the AC input terminal of charger BC. The DC output terminal of charger BC is connected to the positive and negative terminals of battery pack BAT via the normally open contact of contactor KM(2n-1) on one hand, and to the lower end of energized DC circuit breaker QFn on the other hand. The upper end of energized DC circuit breaker QFn is connected to DC bus 1. The positive and negative terminals of battery pack BAT are connected to the lower end of energized DC circuit breaker QF1 via battery evaluation control contactor Kn and diode Dn on one hand, and to the normally open input terminal of contactor KM2 on the other hand. The normally open output terminal of contactor KM2 is connected to the DC input terminal of charger BC.

[0038] The aforementioned diode Dn utilizes its unidirectional conductivity to ensure that the battery pack BAT can only supply power to DC bus 1, while DC bus 1 cannot charge the battery BAT.

[0039] The aforementioned DC power supply monitor 2 is connected to all power supply modules 3 via an RS485 communication bus.

[0040] The online evaluation method using the above-mentioned modular DC power supply and its battery performance online evaluation device includes the following steps:

[0041] Step 1: When the modular DC power supply is running normally, all contactors KM2n of all power modules M1 to Mn are switched to AC 220V input. That is, the normally closed switch of KM2n remains closed, the normally open switch of KM2n remains open, the internal energized DC circuit breaker QFn is in the closed state, the battery evaluation control contactor Kn is in the closed state, the charger BC converts AC power to DC power in AC / DC rectification mode to supply DC bus 1, the contactor KM(2n-1) is in the open state, and the battery pack BAT provides hot standby to DC bus 1 through diode Dn. When AC input 4 loses power, the battery pack BAT provides uninterrupted power supply to DC bus 1 through diode Dn to ensure the reliability of DC power supply.

[0042] Step 2: When it is necessary to evaluate the battery performance of any power module 3 online, assuming that the battery performance of power module 3 numbered Mn is evaluated online, the DC power monitor 2 controls the contactor KM(2n-1) in the power module 3 to be in the open state, controls the battery evaluation control contactor Kn to be open, and controls contactor KM2n to switch the input of the charger BC from AC input 4 to battery pack BAT input. The battery pack BAT supplies power to the DC bus 1 through the charger BC of this power module 3 using DC / DC boost mode. The charger BC is controlled to adjust the discharge current of the battery pack BAT. By comparing the discharge curve of the normal battery, the performance and load capacity of the battery BAT are evaluated online. The part of insufficient power supply is rectified by the charger BC of other power modules 3 to convert AC power into DC power and supply power to the DC bus 1.

[0043] Step 3: After the battery pack completes the performance evaluation, the DC power monitor 2 controls the contactor KM2n to switch from the battery pack BAT input to the AC input 4 input, controls the energized DC circuit breaker QFn to be in the open state, so that this module is disconnected from the DC bus, and at the same time controls the contactor KM(2n-1) to close, the battery evaluation control contactor Kn to remain open, the charger BC uses AC / DC rectification to convert AC power to DC power to charge the battery pack BAT, the energized DC circuit breaker QFx inside other power modules 3 is in the closed state to supply power to the DC bus 1, so as to ensure constant current and voltage limiting charging of the battery pack BAT and constant voltage of the DC bus 1;

[0044] Step 4: After the battery pack is fully charged, the DC power monitor 2 controls the contactor KM1 (2n-1) in the power module 3 to open, the live DC circuit breaker QFn to close, and the battery evaluation control contactor Kn to close, restoring the power module 3 to normal operation.

[0045] Step 5: Following the steps from Step 1 to Step 4, after completing the online evaluation of the battery pack BAT performance in power module 3, the entire modular DC power supply system returns to normal operation.

[0046] Example:

[0047] A modular DC power supply, such as Figure 1 As shown, the modular DC power supply includes a DC bus 1, a DC power supply monitor 2, power modules M1 to Mn 3, and an AC input 4. The connection relationship is as follows: the AC input terminals of all power modules 3 are connected in parallel to the AC input 4, the DC output terminals of all power modules 3 are connected in parallel to the DC bus 1, and the DC power supply monitor 2 is connected to all power modules 3 via an RS485 bus.

[0048] DC bus 1 has a voltage of DC 220V; DC power monitor 2 is the monitoring center of the entire modular DC power supply, and can communicate with each power module 3 via RS485 bus to monitor and control the working status of the module power supply; power modules M1 to Mn 3 are the power supply units of the entire modular DC power supply. Each power module is a miniature DC power supply, including charger BC, battery pack BAT, contactors KM1 and KM2, electrically operated DC circuit breaker QF1, diodes, etc., with the following connection relationship: The AC input is connected to the normally closed input terminal of contactor KM2, and the output terminal of contactor KM2 is connected to the input terminal of the charger. The DC output terminal of the charger is connected to the positive and negative terminals of the battery pack BAT via contactor KM1, and to the lower end of the energized DC circuit breaker QF1. The upper end of the energized DC circuit breaker QF1 is used to connect to the DC bus. The positive and negative terminals of the battery pack BAT are connected to the lower end of the energized DC circuit breaker QF1 via diodes, and to the normally open input terminal of contactor KM2.

[0049] The electrically operated DC circuit breaker QF1 controls the on / off switching of the power module and the DC bus. Contactor KM1 controls the charger to charge the battery. Contactor KM2 controls the switching between AC and DC inputs of the charger. Diodes utilize their unidirectional conductivity to ensure that the battery can supply power to the DC bus while the DC bus cannot charge the battery. The charger has two operating modes: AC / DC rectification and DC / DC boost. In AC / DC rectification mode, it can convert AC power into DC power to supply power to the DC bus or charge the battery pack. When in DC / DC boost mode, the battery DC power can be boosted to supply power to the DC bus for online battery performance evaluation. The battery pack serves as the energy storage unit of the power module, providing backup power to ensure the modular DC power supply. AC input 4 provides AC power to the entire modular DC power supply at a voltage of AC220V. When AC input 4 is powered normally, the charging module in power module 3 rectifies the AC power into DC power to supply power to DC bus 1. When AC input 4 loses power, the battery pack in power module 3 supplies power to DC bus 1.

[0050] Modular DC power supplies use multiple power modules connected in parallel for output. If the battery in any power module experiences an open circuit or other fault, the batteries in other power modules can still supply power normally, improving the reliability of DC power supply. At the same time, there are no current-limiting components between the batteries in each power module and the DC bus, resulting in strong load-bearing capacity for impact loads and ensuring that the feeder switch can reliably trip and isolate faults.

[0051] A method for online performance evaluation of modular DC power supply batteries is provided. The performance evaluation of modular DC power supply batteries adopts an online multi-module automatic sequential execution mode. Only one power module battery is evaluated online at a time, while other power modules provide normal power supply to the DC bus. Then, they are rotated sequentially to achieve online performance evaluation of all power module batteries.

[0052] like Figure 2 As shown, the steps of the online performance evaluation process for batteries are as follows:

[0053] STEP 1: When the modular DC power supply is running normally, all power modules M1 to Mn terminal contactors KM2 switch to AC220V input, the internal energized DC circuit breaker QF1 is in the closed state, the charger converts AC power to DC power in rectification mode to supply power to the DC bus, contactor KM1 is in the open state, the battery pack provides hot standby to the DC bus through diodes, when the AC input power fails, the battery pack provides uninterrupted power supply to the DC bus through diodes to ensure the reliability of DC power supply;

[0054] STEP2: When online evaluation of the battery performance of any power module is required, the DC power monitor 2 controls the contactor KM1 in the power module to be in the open state via RS485 communication, and controls the contactor KM2 to switch the charger input from AC220V to the battery pack. The battery pack supplies power to the DC bus through the charger of this power module in DC / DC boost mode. The charger can be controlled to adjust the discharge current of the battery pack. By comparing the discharge curve of a normal battery, the battery performance and load capacity can be evaluated online. For the part with insufficient power supply, the AC power is converted to DC power by other power module chargers in the rectification mode and supplied to the DC bus for equal distribution.

[0055] STEP 3: After the battery pack completes its performance evaluation, the DC power monitor 2 controls the contactor KM2 via RS485 communication to switch the input from the battery pack to AC220V input. It controls the energized DC circuit breaker QF1 to be in the open state, so that this module is disconnected from the DC bus. At the same time, it controls the contactor KM1 to close, and the charger uses rectification to convert the AC power to DC power to charge the battery pack. The energized DC circuit breaker QF1 inside other power modules is in the closed state to supply power to the DC bus, so as to ensure constant current and voltage limiting charging of the battery pack and constant DC bus voltage.

[0056] STEP4: After the battery pack is fully charged, the DC power monitor 2 controls the contactor KM1 in the power module to open and the energized DC circuit breaker QF1 to close via RS485 communication, restoring the power module to normal operation.

[0057] STEP 5: Following this process, after completing the online performance evaluation of the battery packs in all power modules, the entire modular DC power supply system returns to normal operation.

Claims

1. A modular DC power supply battery performance online evaluation device, characterized in that, The modular DC power supply includes a DC bus (1), a DC power supply monitor (2), power modules (3) and an AC input (4). Power modules (3) M1 to Mn are connected in parallel on the DC bus (1). The AC input terminals of all power modules (3) are connected in parallel to the AC input (4). The DC output terminals of all power modules (3) are connected in parallel to the DC bus (1). The DC power supply monitor (2) is connected in communication with all power modules (3). Each power module (3) includes a charger BC, a battery pack BAT, contactors KM(2n-1) and KM2n, a energized DC circuit breaker QFn, a diode Dn, and a battery evaluation control contactor Kn, where n is the number of the power module (3). Each power module (3) controls the coordination between the energized DC circuit breaker QFn, contactors KM(2n-1), KM2n, and battery evaluation control contactor Kn through a DC power monitor (2), changing the charger BC between AC / DC rectification mode and DC / DC boost mode. When the charger BC is in DC / DC boost mode, the battery is evaluated online by monitoring the discharge current curve of the battery pack BAT in the current power module (3).

2. The modular DC power supply and its battery performance online evaluation device according to claim 1, characterized in that, The charger BC has two working modes, specifically: In AC / DC rectification mode, the AC input terminal receives the AC power from the AC input (4) and outputs a constant voltage DC power to the DC bus (1). In DC / DC boost mode, the DC input terminal receives the DC power from the battery pack BAT, boosts it, and then outputs a constant voltage and constant current DC power to the DC bus (1).

3. The modular DC power supply and its battery performance online evaluation device according to claim 2, characterized in that, The internal structure of the power module (3) is as follows: The AC input (4) is connected to the normally closed input terminal of KM2n. The normally closed output terminal of KM2n is connected to the AC input terminal of the charger BC. The DC output terminal of the charger BC is connected to the positive and negative terminals of the battery pack BAT via the normally open contact of the contactor KM (2n-1) on one hand, and to the lower end of the energized DC circuit breaker QFn on the other hand. The upper end of the energized DC circuit breaker QFn is connected to the DC bus (1). The positive and negative terminals of the battery pack BAT are connected to the lower end of the energized DC circuit breaker QF1 via the battery evaluation control contactor Kn and diode Dn on one hand, and to the normally open input terminal of the contactor KM2 on the other hand. The normally open output terminal of the contactor KM2 is connected to the DC input terminal of the charger BC.

4. The modular DC power supply and its battery performance online evaluation device according to claim 3, characterized in that, The diode Dn utilizes its unidirectional conductivity to ensure that the battery pack BAT can only supply power to the DC bus (1), while the DC bus (1) cannot charge the battery BAT.

5. The modular DC power supply and its battery performance online evaluation device according to claim 4, characterized in that, The DC power supply monitor (2) is connected to all power modules (3) via an RS485 communication bus.

6. The online evaluation method using the modular DC power supply and its battery performance online evaluation device as described in claim 3, characterized in that, The steps for online evaluation are as follows: Step 1: When the modular DC power supply is running normally, all contactors KM2n of the power modules M1 to Mn are switched to AC220V input. That is, the normally closed switch of KM2n is kept closed, the normally open switch of KM2n is kept open, the internal energized DC circuit breaker QFn is in the closed state, the battery evaluation control contactor Kn is in the closed state, the charger BC converts the AC power to DC power in AC / DC rectification mode to supply power to the DC bus (1), the contactor KM (2n-1) is in the open state, the battery pack BAT provides hot standby to the DC bus (1) through diode Dn. When the AC input (4) loses power, the battery pack BAT provides uninterrupted power to the DC bus (1) through diode Dn to ensure the reliability of DC power supply. Step 2: When it is necessary to evaluate the battery performance of any power module (3) online, assuming that the battery performance of the power module (3) numbered Mn is evaluated online, the DC power monitor (2) controls the contactor KM (2n-1) in the power module (3) to be in the open state, controls the battery evaluation control contactor Kn to be open, controls the contactor KM2n to switch the input of the charger BC from AC input (4) to the input of the battery pack BAT, the battery pack BAT supplies power to the DC bus (1) through the charger BC of this power module (3) using DC / DC boost mode, controls the charger BC to adjust the discharge current of the battery pack BAT, and achieves online evaluation of the performance and load capacity of the battery BAT by comparing the normal battery discharge curve. The insufficient power supply is converted from AC to DC by the charger BC of other power modules (3) in the rectification mode and supplied to the DC bus (1) in a shared manner. Step 3: After the battery pack completes the performance evaluation, the DC power monitor (2) controls the contactor KM2n to switch from the battery pack BAT input to the AC input (4) input, controls the energized DC circuit breaker QFn to be in the open state, so that this module is disconnected from the DC bus, and at the same time controls the contactor KM (2n-1) to close, the battery evaluation control contactor Kn remains open, the charger BC uses AC / DC rectification to convert AC power to DC power to charge the battery pack BAT, and the energized DC circuit breaker QFx inside other power modules (3) is in the closed state to supply power to the DC bus (1) to ensure that the battery pack BAT is charged with constant current and limited voltage and the DC bus (1) voltage is constant. Step 4: After the battery pack is fully charged, the DC power monitor (2) controls the contactor KM1 (2n-1) in the power module (3) to open, the live DC circuit breaker QFn to close, and the battery evaluation control contactor Kn to close, restoring the power module (3) to normal operation. Step 5: After completing the online evaluation of the battery pack BAT performance in the power module (3) according to the steps of Step 1-Step 4, the entire modular DC power system is restored to normal operation.

Images