Sensor excitation circuit based on D-type power amplifier

Abstract

The invention discloses a sensor exciting circuit based on a D-type power amplifier, and the D-type power amplifier is applied to an inductive displacement sensor exciting circuit, so that the circuit loss is greatly reduced, and the efficiency is improved. Through the design of the amplitude stabilizing circuit with closed-loop control, the problem of voltage fluctuation after the D power amplifier is loaded is solved. And self-excitation generated by the circuit after closed-loop control is introduced into the amplitude stabilizing circuit is eliminated through a phase-leading correction link. For an inductive sensor system which has a high-power requirement or is sensitive to power consumption, the inductive sensor excitation circuit based on the D-type power amplifier can greatly reduce the measurement loss of the inductive sensor and improve the working performance of the inductive sensor.

Description

technical field [0001] The invention relates to the technical field of electric displacement sensors, in particular to a sensor excitation circuit based on a Class D power amplifier. Background technique [0002] At present, in the excitation circuit for electric displacement sensor measurement, the main types of power amplifiers used are: A / B / AB class power amplifiers; all are linear power amplifiers, the signal always works in the linear region of the triode, and the output transistor (device) acts as a linear regulator. to adjust the output voltage. There is a large voltage drop on the output transistor, the efficiency is reduced, and the heat is obvious. Studies have shown that in general, the efficiency of class A / B / AB power amplifiers is only 40%-60%, while the efficiency of inductive sensor excitation circuits based on class D power amplifiers can reach more than 90%. [0003] When the class D power amplifier is used in the measurement of the electric displacement s...

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Problems solved by technology

[0004] (1) The class D power amplifier itself has a large output impedance, generally 2-8Ω, which is in the same order of magnitude as the impedance value of most measurement circuits. Large fluctuations affect the final measurement accuracy

[0005] (2) The amplitude fluctuation of the output voltage is solved by the closed-loop stabilization circuit, but the output part of the class D power amplifier circuit has its own LC filter, which is used to filter out high-order harmonics. After adding the stabilization circuit, the existence of the closed-loop feedback circuit is easy. Make the circuit self-excited, thereby affecting the stability of the excitation circuit

[0006] (3) The self-excited frequency of the circuit is related to the LC parameter. The specific value is: the smaller the LC product value, the larger the frequency, and the easier it is to eliminate, but at the same time, the larger the cutoff frequency of the LC filter, the worse the filtering effect will be.

[0007] (4) There are distributed capacitances and inductances on the amplitude-stabilizing circuit board. If they cannot be matched reasonably, the phase angle displacement will be caused on the feedback circuit. After the displacement is amplified step by step, it will greatly affect the adjustment accuracy, and even make the The entire closed-loop control system is unstable

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