In order to improve system efficiency and reduce power consumption, the power amplifier drive circuit adopts the integrated circuit L298N based on the bipolar H-bridge pulse width modulation method. 1 Introduction to P ower I ntegrated C ircuit L298N The block diagram of the speed control system is shown in Figure 2.įigure 2 Block diagram of PWM speed control systemģ. The minimum system of the single-chip microcomputer adopts the 16-bit single-chip 80C196KC external expansion interface circuit, which is mainly used to realize the functions of data acquisition and PWM signal generation.
The DC motor speed control system based on 80C196KC and L298N is composed of the smallest single-chip microcomputer system, R/D converter, PWM power amplifier circuit, A/D and D/A conversion circuit, and receiving command interface circuit. Therefore, in the control of DC motors, the PWM control method is mainly used. Because when it encounters mechanical resonance at a particular frequency, it often results in system vibration and howling. PFM means that the on-pulse width is constant and the duty cycle is changed by changing the switching frequency. PWM is by changing the width of the on-pulse, which is commonly referred to as the fixed frequency width modulation method. There are usually two ways to change the duty cycle: PWM and PFM (pulse frequency modulation). The schematic diagram of PWM control is shown in Figure 1. Therefore, it is often called a switch drive device. By changing the duty cycle of the voltage on the armature of the DC servo motor, the average voltage is changed to control the speed of the motor. PWM, or pulse width modulation, refers to the use of the switching characteristics of high-power transistors to modulate a fixed voltage DC power supply, which is turned on and off at a fixed frequency, and the length of the on and off time in a cycle is changed as needed.
Principle of PWM Speed Control Systemģ.1Introduction to Power Integrated Circuit L298Nģ.2 DC Motor Control System Hardware Circuitģ.3 Anti-interference and Electromagnetic Compatibility Design
Therefore, this paper proposes the design of a DC motor PWM control system based on 80C196KC and L298N. And with the advantages of high switching frequency, stable low-speed operation, excellent dynamic performance, and high efficiency, it is widely used in DC motor speed regulation. With computers entering the control field and the continuous emergence of new power electronic power components, PWM (pulse width modulation) speed regulation has become a new way of DC motor speed regulation. In recent years, the structure and control methods of DC motors have undergone great changes. DC motors are widely used in various fields due to their good speed regulation performance, large starting torque and strong overload capacity.
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