Mornsun Power Solution for 1500VDC PV Power System

MORNSUN is proud to introduce a new DC/DC converter, PVxx-29Bxx series, to address the needs of 1500VDC Photovoltaic systems. This series of DC/DC converters accept a wide input from 200-1500VDC providing a standard output voltage of 24V, 12V, and 5V to power monitoring and control circuits in the system. The PVxx-29Bxx simplifies the wiring design reducing the cost of system manufacturing and maintenance when compared with AC power or battery power. This converter also features multiple protection functions that improve system safety when a breakdown occurs.

Paris 2015 Global Climate conference achieved a carbon emission agreement that is legally binding and practical to all parties, which further propel the development and popularity of the new green energy technology, e.g photovoltaic industry, wind power. In 2015, China has passed the Economic and Social Development 13th Five-Year Plan, which includes the continuous development plan for the PV power and it aims to build more PV power facilities to offer 150GW. With the support of domestic and abroad policy, the request of the market, as well as the development of Energy Internet, PV power will grow in scale will offer more intelligent control, which is beneficial to reduce the cost of photovoltaic, promote technological innovation and update the industry.

The common goal of the global PV power industry is to create a type of clean energy with lower costs and higher efficiency. Currently, the PV power system is built on the design of 1000Vdc input. However, the line loss can be reduced if the system can accept higher voltage input, which can have an extra efficiency increment of 1.5%-2.0%. The market research report by GTM estimated that the 1500Vdc PV power system would account for 9% of the global demand in 2016, which is equal to 4.6GW. Therefore, the 1500Vdc PV power system will inevitably be a growing trend in the power industry.

PV power generation system contains solar panel, combiner box, DC power cabinet, inverter and boosting transformer (Diagram 1:PV Power generation System). In this system, in order to reduce the wiring between solar panel arrays and the inverters, the arrays are built by group and connected in parallel to get electric combination into the solar combiner, and then the DC will be provided through DC cabinet to the solar inverter and then into the power grid.

The output of solar panel arrays varies significantly for sunlight from different regions, seasons, and times. And the solar combiner needs to detect every group of the solar array's voltage, current, power, and anti-thunder condition, and realize the functions of failure warning, locating, and communication. The solar inverter needs to detect the voltage, current and drive the control board while converting the DC to AC. Because the solar panel arrays output is normally higher than 1kv, the conventional power module cannot accept the voltage from the high-voltage line as input, if adopting the solution of external power for driving multiple detection units for the solar combiners and inverters, unstable operating voltage, wiring and single shorted circuit problems may occur and cause power failure of the whole detection system.

To meet the PV power generation application requirement, MORNSUN released a series of DC-DC converters with 200-1500VDC input 4000VAC isolation. Additionally. MORNSUN has a pack of DC-DC solutions which can ensure safety isolation in different units of the circuit.

In order to enhance the reliability and practicality, the PV combiner box is equipped with a DC Anti-thunder protection module, DC fuse, circuit breaker, and some functional circuits, such as Control and Processing, Working State Monitoring and Communication Circuit, etc.

Diagram 2 shows a typical monitoring unit solar combiner box. With the feature of 200-1500VDC input, 4000VAC isolation of PVxx-29B24, it becomes much simpler to get power source from the solar panel array and convert it to 24VDC for the monitoring unit. DC-DC converter f0505s-1WR2 is used to drive the hall sensor with isolation between high and low voltage. DC-DC converter B0503XT-2WR2 provides the 3.3V isolated DC for MCU. The transceiver TD501D48H integrates the isolated serial communication signal and isolated power, which can impede electromagnetic interference and avoid ground loop interference. This solution functionally meets the requirements and also provides safety isolation, which is simple and reliable.

In the front end, the combiner box is used to combine the current, and after the DC cabinet monitoring, the DC voltage will be converted into AC through the inverter. The converting process of the inverter is also needed to be monitored, controlled, and communicated to ensure the inverted voltage can meet the requirement. This monitoring unit can accept the wide input range of 200-1500VDC from the bus.

As Diagram 3 shows, PVxx-29B24 gets the power source from a high-voltage bus and step down to 24VDC, and low-drop regulator k7805-500R3 and K7815-500R3 can provide the right voltage with high efficiency for the circuit behind it. B0503XT-2WR2 provides the 3.3V isolated DC for MCU. The transceiver TD501D485H integrates the isolated serial communication signal and isolated power, which can impede electromagnetic interference and avoid ground loop interference. QP12W08S-37 is an isolation DC-DC integrated IGBT driver, which can simplify the design and improve reliability.

PVxx-29Bxx is a high reliability DC-DC converter with 200-1500VDC input, 4000VAC isolation and built-in-multi-prote

The block diagram of PVxx-29Bxx is shown on diagram 5. it uses fly-back topology, using a mature and reliable PWM control IC, and adopting the design of high protection circuit, such as input under-voltage, output over current, and short-circuit protection to achieve high reliability.

In summary, PV energy is a promising market and MORNSUN is to developing the right product for the right application of the industry for cleaner power. Targeting the specific requirement of 1500VDC solar PV system monitoring, MORNSUN offers the PVxx-29Bxx which can accept 1500Vdc input along with offering a full suite of power solutions, to simplify customer design save cost, and ensure system reliability.