PWM controller UC2637 working principle

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Overview:
Modern motor control technology is changing with each passing day, and it is developing rapidly. The DC electric steering gear is applied in many model projects engaged in research and development, and the core part of the DC motor control method uses pulse width adjustment mode to adjust the pulse width of the electric steering gear. Several situations in the working mode of the driver chip UC2637 are discussed, and it is hoped that it can be flexibly applied and can be extended to other use cases.

0 Overview DC motors or DC servos are widely used in many fields. In the field of modern DC motor control, pulse width modulation (PWM) is more and more widely used. In some models I am engaged in The development of human-machine servo loop adopts the switch mode DC motor control chip UC2637 introduced by Unitrode Company of the United States. The principle of the chip is simple, easy to use and high reliability. The operating frequency of PWM wave is set at around 20 kHz. This mode and linear The power amplifier circuit and the level control drive method (bang.bang) have many advantages compared to:
First of all, this control mode works in the switching state, its own efficiency is high, power consumption is small, and there is less heat during stable operation.
Secondly, this control method can be approximated as a proportional link, and the linearity is better at work.
Again, because this control mode works in the high-frequency square wave state, it contains the DC component and the harmonic components, so that the motor can do small amplitude and high-frequency vibration under the action of harmonics. It can effectively remove the dead zone of the motor and accelerate the motor start. The speed and the motor time constant are much larger than the carrier period of the pulse-width-modulated square wave, so the amplitude of the high-frequency vibration of the motor under harmonic action is approximately zero.

1 pulse width adjustment driver chip UC2637 working principle
1.1 UC2637 controller UC2637 basically consists of 4 input voltage divider resistors. 2 comparators, 1 triangle wave generator. Control logic composition. As shown in Figure 1.

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