US 3,947,763 A · C-MOS electronic kWh meter and method for metering electrical energy

Abstract

Metering kWh in an electrical system is accomplished by generating pairs of analog signals, representing current and voltage variables. Each pair of analog signals is multiplied together in a direct pulse-width conversion in a time-division multiplier network. A constant amplitude triangular generator is associated with the multiplier and the multiplier is implemented using C-MOS technology. A separate direct pulse-width multiplier network is provided for multiplying without introducing any phase shift each of the pairs of analog signals to form a series of width and amplitude-modulated pulse signals. The series of modulated pulse signals is converted in, for example, a low-pass filter to a signal having an amplitude representative of average power. For polyphase systems, the signals delivered from each of the multiplier channels are summed at the low-pass filter. An analog-to-pulse rate converter is used for converting the signal representing average power to another series of output pulse signals having a variable signal repetition rate proportional to average power, each output pulse signal representing a quantized amount of electrical energy. A stepping switch and register perform conventional accumulation, storage and display functions in response to the series of output pulse signals delivered thereto.

Claims14

Dependent claims

A method for metering electrical energy in a system comprising the steps of generating a first and a second analog signal, one of the first and second signals being proportional to a voltage and the other of the first and second analog signals being proportional to a current, generating a cyclically varying reference signal, comparing one of the first and second analog signals to the cyclically varying reference signal to generate a pulse train which is width-modulated in accordance with the comparison, coupling the other of the analog signals through a bipolar switch with the actuation of the bipolar switch being controlled by the width-modulated pulse train so that an output pulse train is formed at the bipolar switch output which is width-modulated in accordance with one of the analog signals and amplitude-modulated in accordance with the other of the analog signals.

An electronic kWh meter for metering electrical energy in a system comprising means for generating at least a first analog signal representative of a voltage or current in said system and at least a second analog signal representative of a current or voltage in the system;

at least one multiplier for producing an output signal representative of the product of said at least first and second analog signals, said multiplier comprising means for generating a cyclically varying reference signal, comparator means for linearly superimposing said reference signal and said first analog signal to form a pulse train which is width-modulated in accordance with the comparison of said reference signal with said first analog signal, a selectively actuated bipolar switch continuously coupling the second analog signal to the multiplier output, said switch being actuated by the width-modulated pulse train to form at the multiplier output an output pulse train representative of instantaneous power which is width-modulated in accordance with the first analog signal and amplitude modulated in accordance with the second analog signal;
summing low-pass filter means to which the outputs of said at least one multiplier are connected for forming a pulse train output representative of average total system power;
and an analog-to-pulse rate converter for converting said average total system power pulse train into a series of output pulse signals wherein each pulse is representative of a quantized amount of electrical energy, and means for accumulating said pulses representative of quantized amounts of electrical energy and generating a display proportional to the accumulated quantized amounts of electrical energy.

Dependencies are inferred from the claim text.

C-MOS electronic kWh meter and method for metering electrical energy

Life of this patent

C-MOS electronic kWh meter and method for metering electrical energy

Life of this patent

Abstract

Claims14