Electrical energy measuring multimeter

Claim 2

An electrical energy measuring circuit multiplying a first and second analog input signals, comprising: first input means receiving said first analog input signal; second input means receiving said second analog input signal; analog to frequency converter means producing a train of pulse signals having a pulse repetition rate responsive to the peak values of said first analog input signal; means for sampling said second analog input signal at predetermined times, and having output means producing at least one analog output signal responsive to said second analog input signal; means producing a periodic reference signal; means for comparing the instantaneous values of said reference signal to the instantaneous values of said at least one analog output signal; totalizing means; and switching means selectively connecting said analog to frequency converter means to said totalizing means, said switching means responsive to said means for comparing such that the total of pulse signals stored in said totalizing means is related to the time integral of the product of said first and said second analog input signals.

Claim 3

The electrical energy measuring circuit of claim 1 wherein the analog to frequency converter means includes a first full wave rectifier producing a first rectified output signal in response to the first analog input signal, and includes a voltage to frequency converter producing the train of pulse signals in response to said first rectified output signal.

Claim 4

The electrical energy measuring circuit of claim 1 including a second full wave rectifier producing a second rectified output signal in response to the second analog input signal, and wherein the means for sampling includes a peak detector providing a first analog output signal responsive to the peak values of said second rectified output signal.

Claim 5

The electrical energy measuring circuit of claim 1 wherein the means for sampling includes a first zero crossing detector producing a sampling control signal in response to the first analog input signal, and includes a sample and hold circuit producing a second analog output signal responsive to both the second analog input signal and said sampling control signal.

Claim 6

The electrical energy measuring circuit of claim 1 including a second full wave rectifier producing a second rectified output signal in response to the second analog input signal, and wherein the means for sampling includes a peak detector providing a first analog output signal responsive to the peak values of said second rectified output signal, said means for sampling further includes a first zero crossing detector producing a sampling control signal in response to the first analog input signal, and includes a sample and hold circuit producing a second analog output signal responsive to both said second analog input signal and said sampling control signal.

Claim 7

The electrical energy measuring circuit of claim 1 including a second full wave rectifier producing a second rectified output signal in response to the second analog input signal and wherein the means producing the reference signal includes a counter producing a binary output signal and includes a zero crossing detector responsive to said second rectified signal for incrementing said counter, and further includes a digital to analog converter producing a train of ramp signals responsive to said binary output signal, said train of ramp signals is said periodic reference signal.

Claim 8

The electrical energy measuring circuit of claim 3 wherein the means for comparing includes a first comparator producing a first gate command signal responsive to the differences between the instantaneous values of the reference signal and the instantaneous values of the first analog output signal.

Claim 9

The electrical energy measuring circuit of claim 4 wherein the means for comparing includes a second comparator producing a second gate command signal responsive to the differences between the instantaneous values of the reference signal and the instantaneous values of the second analog output signal.

Claim 10

The electrical energy measuring circuit of claim 8 wherein the means for comparing further includes an inverter receiving the second analog output signal and producing the inverse of the second analog output signal, and includes a third comparator producing a third gate command signal responsive to the differences between the instantaneous values of the reference signal and the instantaneous values of said inverse of the second analog signal.

Claim 11

The electrical energy measuring circuit of claim 5 wherein the means for comparing includes a first comparator producing a first gate command signal responsive to the differences between the instantaneous values of the reference signal and the instantaneous values of the first analog output signal, and includes a second comparator producing a second gate command signal responsive to the differences between the instantaneous values of the reference signal and the instantaneous values of the second analog output signal.

Claim 12

The electrical energy measuring circuit of claim 10 wherein the means for comparing further includes an inverter receiving the second analog output signal and producing the inverse of the second analog output signal, and includes a third comparator producing a third gate command signal responsive to the differences between the instantaneous values of the reference signal and the instantaneous values of said inverse of the second analog signal.

Claim 13

The electrical energy measuring circuit of claim 7 wherein the switching means includes a first gate for selectively connecting the analog to frequency converter means to the totalizing means in response to the first gate command signal.

Claim 14

The electrical energy measuring circuit of claim 18 wherein the switching means includes a second gate for selectively connecting the analog to frequency converter means to the totalizing means in response to the second gate command signal.

Claim 15

The electrical energy measuring circuit of claim 9 wherein the switching means includes a second gate for selectively connecting the analog to frequency converter means to the totalizing means in response to the second gate command signal, and includes a third gate in parallel with the second gate for selectively connecting the analog to frequency converter means to the totalizing means in response to the third gate command signal.

Claim 16

The electrical energy measuring circuit of claim 10 wherein the switching means includes a first gate for selectively connecting the analog to frequency converter means to the totalizing means in response to the first gate command signal, and includes a second gate in parallel with the first gate for selectively connecting the analog to frequency converter means to the totalizing means in response to the second gate command signal.

Claim 17

The electrical energy measuring circuit of claim 11 wherein the switching means includes a first gate for selectively connecting the analog to frequency converter means to the totalizing means in response to the first gate command signal, and includes a second gate in parallel with the first gate for selectively connecting the analog to frequency converter means to the totalizing means in response to the second gate command signal, and further includes a third gate in parallel with the first and second gates for selectively connecting the analog to frequency converter means to the totalizing means in response to the third gate command signal.

Claim 18

An electrical energy measuring circuit, measuring volt-ampere-hours, responsive to a voltage and a current delivered to a load, including: first input means receiving a first analog input signal responsive to the time derivative of said current; second input means receiving a second analog input signal responsive to said voltage; analog to frequency converter means producing a train of pulse signals having a pulse repetition rate responsive to the peak values of said first analog input signal; means for sampling said second analog input signal at its peak values, and for producing a first analog output signal responsive to said peak values of said second analog input signal; means producing a train of ramp signals having an instantaneous value related to the frequency of said second analog input signal; means for comparing the instantaneous values of said first analog output signal to the instantaneous values of said train of ramp signals; totalizing means; and switching means for selectively connecting said analog to frequency converter means to said totalizing means, said switching means responsive to said means for comparing such that the total of pulse signals stored in said totalizing means is related to the time integral of the product of said voltage and said current.

Claim 19

An electrical energy measuring circuit, measuring volt-ampere-hours, responsive to a voltage and a current delivered to a load, including: first input means receiving a first analog input signal responsive to the time derivative of said current; second input means receiving a second analog input signal responsive to said voltage; analog to frequency converter means producing a train of pulse signals having a pulse repetition rate responsive to the peak values of said first analog input signal; means for sampling said second analog input signal at its peak values, and for producing a first analog output signal responsive to said peak values of said second analog input signal; means producing a train of ramp signals having an instantaneous value related to the frequency of said second analog input signal; means for comparing the instantaneous values of said first analog output signal to the instantaneous values of said train of ramp signals; totalizing means; and switching means for selectively connecting said analog to frequency converter means to said totalizing means, said switching means responsive to said means for comparing such that the total of pulse signals stored in said totalizing means is related to the time integral of the product of said voltage and said current.

Claim 20

An electrical energy measuring circuit, measuring watthours, responsive to a voltage and a current component of an AC energy delivered to a load, including: first input means receiving a first analog input signal responsive to the time derivative of said current component; second input means receiving a second analog input signal responsive to said voltage component; analog to frequency converter means producing a train of pulse signals having a pulse repetition rate responsive to the peak values of said first analog input signal; means for sampling said second analog input signal at the times when said first analog input signal has a value of zero, and for producing a second analog output signal responsive to the value of said second analog input signal when said first analog input signal has a value of zero; means producing a train of ramp signals having an instantaneous value related to the frequency of said second analog input signal; means for comparing the instantaneous values of said second analog output signal to the instantaneous values of said train of ramp signals; totalizing means; and switching means for selectively connecting said analog to frequency converter means to said totalizing means, said switching means responsive to said means for comparing such that the total of pulse signals stored in said totalizing means is related to the time integral of the produce of said voltage and current components.

Claim 21

An electrical energy measuring circuit, measuring watthours, responsive to a voltage and a current component of an AC energy delivered to a load, including: first input means receiving a first analog input signal responsive to the time derivative of said current component; second input means receiving a second analog input signal responsive to said voltage component; analog to frequency converter means producing a train of pulse signals having a pulse repetition rate responsive to the peak values of said first analog input signal; means for sampling said second analog input signal at the times when said first analog input signal has a value of zero, and for producing a second analog output signal responsive to the value of said second analog input signal when said first analog input signal has a value of zero; means producing a train of ramp signals having an instantaneous value related to the frequency of said second analog input signal; means for comparing the instantaneous values of said second analog output signal to the instantaneous values of said train of ramp signals; totalizing means; and switching means for selectively connecting said analog to frequency converter means to said totalizing means, said switching means responsive to said means for comparing such that the total of pulse signals stored in said totalizing means is related to the time integral of the produce of said voltage and current components.