Wuhan University of Technology Electronic Design Competition Second Prize Team Member: Jiang Hao, Wang Zhi, Huaxuan Yibo Instructor: Zhang Jialiang Competition Topic: DC Motor Control System

1. System design

The 12V DC regulated power supply supplies power to the boost circuit and auxiliary power supply. The boost circuit then supplies power to the motor drive. The auxiliary power supply supplies power to the STM32F407, encoder and current detection circuit. The current detection circuit and encoder measure the real-time current and speed of the motor, and transmit the data to the STM32F407 microcontroller for processing. The microcontroller compares and calculates these data with the set target data, and outputs a PWM wave with a certain duty cycle to control the motor. The speed reaches the target speed and the current reaches the target current, realizing closed-loop control of the motor. The overall block diagram of the system is shown in the figure below.

2. Hardware design

1. Boost circuit design

The XL6019 is a synchronous boost converter with an operating input voltage between 5V and 40V and a maximum output current of up to 5A. This solution can provide +15V power supply to the motor and maintain high efficiency under full load conditions.

2. Motor drive circuit design

Since this question requires forward and reverse control of the motor, we use a microcontroller to output a square wave signal through the PWM1 and PWM2 pins, and change the duty cycle of the PWM signal to achieve speed adjustment. Therefore, a motor drive circuit is needed. HIP4082 can control four pins at the same time. The switching of the circuit MOS tube reduces the number of original components used, and the built-in Schmitt trigger can be directly driven by the microcontroller pins. It consumes less energy, has higher efficiency, and has a simple circuit.

3. Current detection circuit design

The current detection circuit converts the current signal into a voltage signal and amplifies it. Then the microcontroller samples this voltage signal to calculate the current. The INA271 current detection amplifier can operate independently in the common mode voltage range of -16V to 80V. The voltage drop on the current sensing resistor is detected under the condition of the power supply voltage, and a matching resistor gain network is integrated to minimize the gain error and reduce temperature drift. The circuit is simple, stable and reliable.

4. Auxiliary power supply design

In order to meet the requirements of the topic, we need to design an auxiliary power supply to power the microcontroller and measurement system. Here we use a variety of DC-DC chips including TPS5450 to provide 5V and 3.3V power supply voltages for other circuits, and have a large number of inputs and outputs. interface, greatly reducing the difficulty of subsequent debugging.

3. Software design

In the motor control system, the microcontroller measures real-time speed and current through the encoder and current detection circuit, and feeds the results back to the microcontroller. The microcontroller compares these data with the set target data, calculates the PWM wave duty cycle, and outputs PWM Control the motor to reach the target speed and current to achieve closed-loop control of the motor.