Method and apparatus for measuring of electrical power and use thereof

摘要

The invention relates to a method and an apparatus for measurement of electrical power and electrical energy consumed or produced in an electric application such as a domestic appliance or a generator. This takes place by performing a measurement of an electrical power yielded in a transistor to which a current signal and a voltage signal is applied depending on a voltage (U) across and a current (I) in the electric application. The current signal and the voltage signal are proportional to the electrical energy and the electrical power consumed or produced in the electric application. The apparatus for measurement of an electrical power comprises a first circuit with a transistor and a second circuit with a transistor. The first circuit is used as a measuring circuit and the second circuit is used as a reference circuit. A current signal is applied to the first circuit, respectively the second circuit. A voltage differnce, alternatively a temperature difference, is measured as a function of the electrical power and consequently the temperature change and subsequent voltage change taking place in the transistors in the first circuit, respectively the second circuit. The current signal leads to errors caused by non-linearity and depending on the degree of load. This error is outbalanced as a current signal is applied to both the transistor in the first circuit and the transistor in the second circuit. Furthermore, a temperature impact from the surroundings will be outbalanced in the same manner.