Symmetric PWM control signal generator

Abstract

In the symmetrical PWM control signal generator of the present invention, an external voltage-controlled oscillator transmits a frequency modulation signal to it, wherein the signal generator includes an N+1-bit counter whose input terminal receives the output pulse of the VCO, and counts from 0 to The state of all 1s is a cycle, and the lower N bits of the processed signal are sent to one input terminal of the N-bit comparator A, and the other input terminal of the comparator A receives the N-bit comparison value output by the controller for comparison, and outputs the corresponding processing signal , and then output the pulse signal to one input terminal of the frequency division circuit A by two, and the other input terminal of the frequency division circuit A receives the highest bit of the output count value of the N+1 bit counter, and realizes frequency division by two after logical operation; In the B-phase circuit, the input of the N-bit comparator B comes from the N+1-bit adder, and the two input terminals of the N+1-bit adder respectively receive the output signal of the N+1-bit counter and the N+1 Bit offset, which enables phase modulation.

Description

technical field [0001] The invention relates to the technical field of PWM (Pulse Width Modulation), in particular to a symmetrical PWM control signal generator applied to an ultrasonic motor drive control system. Background technique [0002] Ultrasonic motor drive circuits have many different structural forms, and the push-pull drive circuit is one of them. Due to its low cost and high reliability, this drive circuit structure has broad application prospects. [0003] The basic structure of the ultrasonic motor push-pull drive circuit is as follows: figure 1 As shown, the push-pull circuit is directly connected to the ultrasonic motor to achieve voltage amplitude amplification, and the secondary winding of the transformer is used to form a resonance with the capacitive piezoelectric ceramic sheet of the ultrasonic motor to filter out the harmonic components in the square wave driving voltage to realize Approximate sine wave drive. The ultrasonic motor in the figure is a ...

AI Technical Summary

Problems solved by technology

Existing functional modules that can provide symmetrical PWM control signals are usually independent chips, which are difficult to integrate; and there is no symmetrical PWM control signal generator functional module that directly meets the requirements of ultrasonic motor push-pull drive, so it is difficult to generate adjustable frequency and amplitude modulation. , phase-modulated two-phase four-way PWM signal

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