DC72V Smps With Low-voltage Auxiliary Power Supply 450W

Core Functionality Explained

1,72V 450W Main Power Supply:

72V Output Voltage: This is a relatively high voltage, ideal for charging multi-cell lithium-ion/polymer battery packs. For example, it can charge an 18S (18-cell) lithium battery (nominal voltage 3.7V * 18 = 66.6V, charging cutoff voltage is typically 4.2V * 18 = 75.6V). High voltage transmission effectively reduces current during charging, thus reducing line loss and heat generation, which is especially important for high-power charging.

450W Output Power: This determines the charging speed. For a large industrial drone or surveying drone, its battery capacity may reach 10000mAh or even higher. 450W power can significantly shorten charging time and improve operational efficiency.

2,Low-voltage auxiliary power supply controls high-voltage output:

This is a key feature of this power supply used in smart chargers. It means that the power supply has two relatively independent power supply sections:

Main power circuit: Responsible for providing a high-power output of 72V/450W.

Low-voltage auxiliary power supply: A low-power power supply 12V,that is always in standby mode, powering the power supply's own control circuitry and the external charging controller.

"Controlling high-voltage output" means that external devices (such as the main control board of a drone's smart charger) can safely start or stop the 450W 72V main output using a low-voltage, low-current signal (such as an ON/OFF switch signal, PWM signal, or CAN bus command).

Application Analysis in Drone Chargers:

System Connection and Workflow

1,System Composition

This switching power supply serves as the system's "energy source."

External charging controller: An independent intelligent control board containing an MCU (microcontroller), voltage/current detection circuitry, and communication modules (such as CAN or UART). This control board is powered by the low-voltage auxiliary power supply of the switching power supply.

Connection: The charging controller connects to the "enable" or "remote control" terminal of the switching power supply via signal lines.

2,Workflow:

Standby: After the entire system is connected to mains power, the 72V main output is off, with no high-voltage output, ensuring safety. At this time, the low-voltage auxiliary power supply is operational, powering the charging controller, which is in standby mode.

Charging Initiation: The user connects the drone battery to the charger. The charging controller identifies the battery via a communication port (such as a CAN bus) and completes a "handshake" protocol. Then, the controller sends a low-voltage enable signal to the switching power supply.

Power Output: Upon receiving the enable signal, the switching power supply's internal main circuit starts, outputting 72V DC. Note: At this stage, the 72V is "coarse" and not yet precisely regulated.

Intelligent Charging: The charging controller begins operation, using its DC-DC circuit (such as a Buck converter) to chop and regulate the 72V, generating precise charging voltage and current according to a preset charging algorithm (such as CC/CV, constant current/constant voltage) for safe and rapid battery charging.

End of charging: When the battery is fully charged or the user stops charging, the charging controller first stops power regulation, then removes the enable signal sent to the switching power supply.

Shutdown: The main output of the switching power supply immediately shuts down, and the system returns to a safe standby state.