The intelligent information age greatly increases electricity demand, which, in return, pressures people into seeking for green power generation due to the severe environmental pollution and energy consumption. Solar PV power generation is expected to alleviate the pressure. With government’s policy support and less cost of power generation, energy storage systems are brought in tens of thousands of households. For the entire household energy storage system, MORNSUN provides a complete power solution to simplify customer’s design and increase system’s reliability.
Structure and components of a household energy storage system
A household energy storage system is currently divided into two kinds, grid-connected and off-grid. A grid-connected household energy storage system is mixed-powered by solar and the energy storage system, including five parts:
- 1.Solar array
- 2.Grid-connected inverter
- 3.BMS (battery management system)
- 4.Battery pack
- 5.AC load
When the utility works normally, the solar grid-connected system and the utility together power the load. When the utility powers off, the energy storage system and the solar grid-connected system together power the load. The grid-connected household energy storage system is divided into three working modes.
- 1.solar provides energy storage and powers the utility.
- 2.solar provides energy storage and powers part of residential electricity.
- 3.solar only provides energy storage.
An off-grid household energy storage system is independent, without any electrical connection to the grid. Therefore the whole system does not need grid-connected inverter except PV inverter. The off-grid household energy storage system is also divided into three working modes.
- 1.solar provides energy storage and powers residential electricity on sunny days
- 2.solar and energy storage battery power residential electricity in cloudy days
- 3.energy storage battery powers residential electricity at dusk and on rainy days
In summary, current demands for energy storage equipment mainly are BMS management system, PV grid-connected inverter and energy storage inverter. Combined the demands with the safety isolation requirement of the PV system’s unit circuits, MORNSUN puts forward a complete power solution of a control unit.
Power Solution for BMS management system
The battery is the core energy storage device of the system and needs to be monitored online status in real time, so the importance of BMS is self-evident. In the BMS management system, BCU real-time communicates with
- 1.CAN bus and BMU to get monomer voltages, cabinet temperature, insulation resistance and others
- 2.current sensor to collect charge and discharge current and dynamic calculation SOC
- 3.touch screen to display relevant data
The BCU calculates and analyzes all the information of the battery pack and then intelligently manages the system, communicating with the independent CAN bus and achieving the secondary protection of charge and discharge through a relay. The latter ensures an effective isolation for strong electricity and weak electricity, meets customer’s demand for diverse security control and guarantees a stable and efficient operation of the system.
Practical example diagram 3:
Isolation voltage conversion is the main core of a power solution for BMS management system in the energy storage system. The main control unit is mainly based on a 24VDC system, and the power of the whole main control unit is less than 5W. Therefore, URB2405YMD-10WR3 offering 5VDC output voltage is recommended to power F0505XT-1WR2 and LDO. The LDO converts 5VDC into a 3.3V output voltage to power MCU. 6 pieces F0505XT-1WR2 in the system is used to power four CAN modules, voltage detection circuit, insulation detection circuit and a current detection circuit, and isolate power circuit, signal circuit and communication module at the same time to reduce interference and improve the stability and reliability. In addition, MORNSUN automotive-grade power supply CF0505XT-1WR2 is widely used in automotive BMS system.
Power Solution for solar PV inverter monitoring unit
Solar PV components converge energy and inverter converts DC into AC. The process of the inverter needs to be monitored, controlled and communicated so as to ensure its voltage to meet the requirement. This monitoring unit can directly get power from the utility.
As shown in Diagram 4, LH series directly gets power from the utility and converts it into 24V output voltage, which is converted into a 5VDC output voltage by non-isolated switching regulator K7805-500R3. B0503XT-2WR2 outputs 3.3V to power the MCU with isolation function. Isolated high-speed TD501D485H can inhibit electromagnetic interference and rise the ground loop’s resistance to protect the system circuit from an external network. In addition, MORNSUN developed an isolated driver QP12W08S-37 integrating DC/DC power supply, specialized for full-bridge IGBT, to simplify the design of the customer’s driven-control circuit and improve the reliability.
Power Solution for solar PV grid-connected inverter monitoring unit
Een aan het net geconnecteerde zonnepaneel omvormer (ook Bi-directionele omvormer genoemd) bestaat uit een AC/DC unit, DC/DC unit, controle unit en transfer relais unit. Deze energieopslag omvormer wordt vanuit twee soorten voedingsapparatuur gevoed. De ene is het elektriciteitsnet en de andere de zonnepanelen.
Practical example diagram 5:
As shown in Diagram 5, the power selection of AC/DC Converter should mainly take the power of the main control board and fan into account. The equipment power in the above system is 15KW. AC/DC Converter LH40-10B24 offering 24V output voltage is recommended to power the fan and the main control board. For the main control board, it’s recommended to use R3 DC/DC Converters URB2415YMD-10WR3 to power IGBT driver and URB2405YMD-6WR3 to power MCU and communication module. URB_YMD-6/10WR3 series apply fully automated production process, greatly reducing the labour costs. With superior performance ahead of the peer level and highly cost-effective, they fully meet the overall cost demand of solar PV industry.
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