[Nanjing Post and Telecommunications School Competition] CNC Power Supply

Question requirements: Design and produce a digitally controlled DC source (using the existing DCDC module). The input voltage ( 36V ) is provided by a DC regulated power supply. In constant voltage mode, the output DC voltage is adjustable from 1 to 33 volts. In constant current mode, The output current is adjustable from 0.02 to 2.50A , and the power remains at 10 watts in constant power mode .

Award information: Second prize in school competition

Overview of the work: The numerical control power supply implements functions around the BUCK circuit, INA282 current detection circuit and microcontroller system.

The BUCK circuit mainly implements the voltage reduction function. It uses the IR2109S to drive the MOS tube to simulate the switching action of the schematic diagram, and adds the capacitance and inductance of the subsequent stage to reduce the voltage. The formula: Vout=Vin*D (duty cycle), duty It is realized through the PWM output by the microcontroller.

INA282: INA282 mainly amplifies the voltage at both ends of the sampling resistor, and then sends it to the AD of the microcontroller for sampling. The current in the circuit passes through the sampling resistor, and uses Ohm's law: U=IR to obtain the voltage at both ends of the sampling resistor, and then amplifies it through INA282. Leave it to AD for sampling.

Microcontroller: The microcontroller monitors the data of the entire circuit by dividing the voltage of the BUCK circuit output voltage and sampling the voltage of INA282, and then dynamically approaches the target value through the PID algorithm.