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Temperature Compensation for Transformer-type Transducer
(2021-01-01)
Songsuwankit, Kanoknuch
;
Riewruja, Vanchai
;
Watanachaturaporn, Pakorn
;
Rerkratn, Apinai
;
Petchmaneelumka, Wandee
A novel technique to compensate the temperature effect of a transformer-type transducer is proposed in this paper. The effect of the ambient temperature on the transformer-type transducer is investigated from a primary-winding current. The advantage of the proposed technique is that the temperature effect is compensated without requiring a temperature sensor, making it suitable for applications in robotic and automation systems operated in harsh environments. The primary-winding current of the transducer is generated using a second-generation current conveyor (CCII). The excitation signal of the transformer-type transducer is driven by the CCII and the current flowing through the primary winding is transferred to an output signal of the CCII. The deviation of the primary-winding current due to the temperature effect is evaluated from the output signal of the CCII. The temperature effect on the transducer is manipulated by a closed-loop principle using a subtract-and-sum action instead of a traditional proportional-plusintegral action to eliminate the deviation of the primary-winding current. Therefore, the temperature effect on the transducer is compensated. A linear variable differential transformer (LVDT) is used to demonstrate the proposed technique, whose performance is discussed in detail and confirmed experimentally. All devices used in this experiment are commercially available. Experimental results show that the measured error of the output signal from the LVDT at 70 C can be reduced from 6.2% without temperature compensation to 0.06% by using the proposed technique, which has the advantages of a low cost, simple configuration, and high performance.
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Simple and low-cost readout circuit for differential resistive sensors
(2018-09-01)
Katman, Ratchanoo
;
Rerkratn, Apinai
;
Kaewpoonsuk, Anucha
In this paper, a simple and low-cost readout circuit for differential resistive sensors is presented. The realization method is based on the relaxation oscillation technique, which utilizes the operational amplifiers (op-amps) with a single supply voltage. The oscillating output Duty-Cycle is proportional to the difference of two sensing resistances. In comparison with the traditional voltage divider circuit or the Wheatstone bridge circuit or the previously reported readout circuit based on CCIIs, the proposed circuit can be interfaced with microcontroller without using an analog-to-digital converter. Theoretical predictions are supported by the PSPICE simulation results and the experimental data. In applying a slide potentiometer with changes of slider positions of ±15 mm, it is found that the maximum error of the proposed circuit is approximately-2.90% of full-scale. Copyright © 2018 Praise Worthy Prize S.r.l.-All rights reserved.
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Simple DC-excited resistance-to-period converter using CFOAS
(2018-05-01)
Kaewpoonsuk, Anucha
;
Katman, Ratchanoo
;
Rerkratn, Apinai
This paper presents a new method to implement a resistance-to-period converter for DC-excited resistive sensor. The proposed technique makes use of the characteristic of a controllable unity-gain inverting/non-inverting amplifier formed by current feedback operational amplifiers (CFOAs). Experimental results that verify the performance of the proposed circuit are also included.

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