文档介绍：Measurement 39 (2006) 73–79
ate/measurement
A simple VFC based wattmeter suitable for application
at industrial frequency
Hugo Calleja *
Cenidet—Electronics Department, . Box 5-164, Cuernavaca, Morelos 62050, Me´xico
Received 2 September 2004; received in revised form 7 July 2005; accepted 21 July 2005
Available online 19 October 2005
Abstract
In this paper, the design of a simple AC wattmeter is presented. Its main features are that it uses a multiplier built
with two voltage-to-frequency converters (VFC), and that it can be easily connected to a digital instrument, without
further analogue conditioning. The design process is described in detail, and two design approaches are presented. Tests
performed in a prototype validate the suitability of the meter. A limitation is that it can only be used with null-average
signals, such as those usually those found in AC metering applications.
Ó 2005 Elsevier Ltd. All rights reserved.
Keywords: Wattmeter; Multiplier; Voltage-to-frequency converter
1. Introduction based on the o-resistive effect [4], the elec-
tro optic crystal multiplier [5], and a technique
The measurement of power requires the multi- based on a transistor for multiplication and con-
plication of voltage and current, followed by the version to the thermal domain [6] are some exam-
averaging of the product. Several methods to per- ples of