D. Pulse width modulation.
Answer analysis: PWM speed regulation is called pulse width modulation.
PWM speed regulation method explanation
PWM (Pulse Width Modulation), that is, pulse width modulation, is a modulation technology that controls the average power of the signal by adjusting the width of the pulse signal. In the field of motor speed regulation, PWM speed regulation is to control the speed and torque of the motor by changing the duty cycle of the motor input voltage. Specifically, PWM speed regulation is to switch the DC power supply through a switching device (such as a transistor or IGBT), and control the average value of the motor input voltage by changing the on-off time of the switch, that is, the width of the pulse, so as to achieve precise control of the motor speed.
PWM speed regulation working principle
1. Signal sampling and conversion: The controller will first sample the input signal (such as voltage or current) and convert it into a digital signal.
2. PWM signal generation: The controller generates a PWM signal according to the set control signal. In this process, the controller sets a fixed frequency (such as 10kHz) and adjusts the width of each pulse as needed.
3. Pulse width modulation: Pulse width is regulated by comparing the input signal with a reference signal (usually a variable voltage). The controller determines the high-level time length of each pulse by continuously comparing the input signal with the reference signal. If the input signal is large, the high-level time of the pulse will increase; if the input signal is small, the high-level time of the pulse will decrease.
4. Motor speed control: During the entire PWM cycle, the motor speed can be regulated by changing the high-level time length of the pulse width. When the pulse width is widened, the motor speed increases; when the pulse width is narrowed, the motor speed decreases.
5. Precise speed regulation: Through the continuous adjustment of the controller, the average voltage of the PWM signal matches the required motor speed, thereby achieving precise speed regulation.
Advantages of PWM speed regulation
* High precision: PWM speed regulation can achieve high-precision speed and torque control, and is suitable for various occasions requiring precise control.
* Wide applicability: PWM speed regulation is suitable for various types of motors, including DC motors, induction motors, and permanent magnet synchronous motors.
* Easy to use: The PWM speed control system is relatively simple, does not require complex circuits and control algorithms, and has low cost.
In summary, the PWM speed control method has been widely used in the field of motor control due to its high precision, wide applicability and ease of use.