JPS59180371A - Integrating ammeter - Google Patents

Abstract

PURPOSE:To widen a dynamic range by inputting the output of a constant-multiple-voltage generating circuit to a comparator through a Miller integration circuit, opening and closing a switch by an output signal of pulse-width modulation, and leading in a signal proportional to current consumption. CONSTITUTION:A current transformer 11 performs conversion to the signal proportional to the current consumption of a feeder, and a pulse-width modulation type time-series multiplying circuit 12 inputs the signal under the on/off control of a switch circuit 124 and supplies it to an LPF13 with an integration function. A voltage obtained by integration is converted by a voltage-frequency converting circuit 14 into a pulse signal, which is counted to integrate the current. The circuit 12 is equipped with the constant-multipled-voltage generating circuit 121 which generates a constant multiple voltage, Miller integration circuit 122, and comparator A4 which compares and feed the output of the circuit 122 back to the circuit 122 and imposes pulse-width modulation upon the constant multiple voltage, and the circuit 124 is turned on and off according to the output signal of the comparator and its inverted signal. Consequently, the current is integrated with high precision even at the time of less loading and against a distortion wave.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in an 8R calculation ammeter that integrates electricity a.

[Technical background of the invention and its highlights]

Conventionally, when integrating current, the input current is full-wave rectified by a full-wave rectifier circuit that is a modified time division multiplication circuit, and the rectified output is integrated to perform current integration. Figure 1 is a diagram showing the overall configuration of the integrating ammeter, in which the current transformer I converts the signal into a signal proportional to the consumption current of the power supply line, and then the time-sharing full-wave rectifier circuit 2 performs full-wave rectification. This rectified output is then integrated by a low-pass filter 3 and converted into a voltage signal proportional to the current, and then converted back into a pulse signal with a frequency proportional to the voltage by a subsequent voltage-frequency conversion circuit 4 and output.

Specifically, the current transformer 11, the full-wave rectifier circuit 2, and the low filter 3 are of the configuration shown in FIG. , comparator A2+inverter X1, and a bridge circuit 2a including four switches 81 to S4. To describe the operation of the full-wave rectifier circuit 2, the current transformer 1 supplies a signal ±eit which is proportional to the current consumption of the power supply line to the bridge circuit 2a, and also supplies a signal e to the operational amplifier 7'AZ. After configuring this operational amplifier AI as a voltage follower and converting the impedance of the signal e7,
This circuit output is converted into a t4 pulse by a comparator A2. Then, as shown in FIG. 3, when the signal 10e3i is in the positive region, the comparator A2 outputs a logic signal of "work", turns on the switches Sl and S, and the signal 10e3i is in the positive region. Output. Further, when the signal +e6 is in the negative region, the 0'' of the comparator A2 is inverted by the inverter X1 to convert it into a logic signal of 1'', and this signal is used to switch the switch S1.

Turn on S4 and output a signal in the positive region of signal -ei.

Therefore, a signal as shown in FIG. 3 is output from the full-wave rectifier circuit 2. Therefore, after integrating the output of this full-wave rectifier circuit 2 with a subsequent low-pass filter 3 and converting it into a DC voltage,
A voltage-frequency conversion circuit 4 converts the voltage into a pulse signal with a frequency proportional to the voltage and outputs the signal. Therefore, if this pulse signal is counted and integrated, the current will be integrated. However, in the case of the full-wave rectifier circuit 2 as shown in FIG. 2, the following problem exists. First, signal 10i is operational 7'AZ
, Konno9reta A, ? It is converted into an f pulse, but since there is an offset voltage in these O and A7'AI etc., it is difficult to accurately judge the input current of a light load.
Moreover, the linearity also deteriorates. In addition, since the signal 10ei is directly input to the operational amplifier A1 etc., the switches SL to S
The opening/closing control of No. 4 has the problem of being directly affected by distorted waves (harmonics). Furthermore, since the response speed of the operational amplifier A1 etc. is limited, there is a problem that the signal +〇i is always delayed and multiple outputs from the switch circuit 2a. Furthermore, if there is an offset voltage in the amplifier fA1, etc., the opening/closing time of the switches 81 to S4 will be shortened, and the output level in FIG. It has the disadvantage of being small.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and provides an integrating ammeter that can integrate current with high precision even during light loads and distorted waves, and that can have a wide range of dynamics and displacement. The purpose is to

[Summary of the invention]

The present invention has a Miller integrator circuit and a hysteresis converter R regulator, and the output of the hysteresis comparator is fed back to the Miller integrator circuit to form a self-excited oscillation circuit. Input a voltage that is a constant times the output of the regulator/? By pulse width modulation, the pulse width modulation time-division multiplication method is used to acquire and integrate a signal proportional to the current consumption of the power supply line.

[Embodiments of the invention]

FIG. 4 is a block diagram showing an embodiment of the present invention.
Reference numeral 11 designates a current transformer that converts the signal into a signal proportional to the current consumption of the power supply line, a 12μ·cis width modulation type time-division multiplication circuit, 13 a low-pass filter with an integration function, and I4 a voltage-frequency conversion circuit.

Specifically, the Cruz width modulation type time division multiplication circuit 12 is constructed as shown in FIG.

A constant voltage doubler generating circuit 121 that outputs e and a resistor R3
, a capacitor C and an operational amplifier A3, and a Miller integration circuit 1 that integrates the constant multiplied voltage with a time constant R3·C.
22 and this integral output, a logic signal "1" is generated.
A hysteresis controller y I?
- Inverter X2 that inverts the output of this controller or regulator A4, and the output of this inverter Voltage dividing circuit 123 supplied to the inverting input terminal of A4, hysteresis comparator A4 and @1'' of inverter X2
Four analog switches 81 to S4 closed by a signal
It is composed of a different switch circuit 124.

Next, the operation of the integrating ammeter configured as above will be explained. First, the current transformer 11 converts the signal e4 into a signal proportional to the current consumption of the power supply line, and then supplies the signal e() to the switch circuit 124. At this time, the pulse width modulation type time division multiplier circuit 12 In other words, the Miller integration circuit 122 converts the constant multiplied voltage generated from the constant multiplied voltage generation circuit 121 into a positive or negative direction with a time constant R3·C based on the output of the hysteresis condenser Al regulator A4. Integrate in the direction.Now, use the hysteresis condenser/lator A
The time interval when the output of 4 is logic @1# is t, logic''
If the time interval at the time of "0"' is t, then this integral output ek is sent to the Miller integration circuit in each time interval ta, tb.
is =-e.

becomes.

To this, 1a, 1. If you ask for it, you will get it. Therefore, the A pulse data cycle D output from the hysteresis comparator A 4 ybh.

D becomes . Therefore, with this pulse duty cycle D, the analog switch S! , S4 is turned on to take in the signal ei, and the ) 9 duty cycle D is input to the inverter X2.
After reversing, analog switch S! Turn on +83 and signal e
If i is taken in and integrated by the low-pass filter 13, the following outputs are obtained at both output ends of the low-pass filter 13. However, voltage signals e and e that are proportional to the current ±ei are obtained. Therefore, OP
on voltage-frequency conversion circuit 14 converts those voltage signals eo p
It converts r e on into a /Jrus signal and outputs it.

Therefore, according to the configuration of the embodiment described above, the offset of the operational amplifier A3 is canceled by the integral operation, and the offset of the operational amplifier A3 is not canceled by the voltage at the inverting input terminal, but by a constant. Since the doubled voltage is integrated while being pulse-modulated by the Miller integration circuit 122, the switching circuit 124 can be controlled to open and close regardless of the light load. Further, if the time constant of the Miller integration circuit 122 is set high, the multiplication accuracy of the time division multiplication circuit I2 is also improved, and it is possible to capture and measure the signal e4 with high precision even for distorted waves. In addition, with conventional products, the output of the full-wave rectifier circuit was lowered due to the offset voltage, making the output of the voltage-frequency conversion circuit narrower, but this device uses a constant voltage to increase the output of the multiplier circuit. Because of this, it is possible to use a wide range of Guinamik Renzo.

The above embodiment has a configuration in which the output of the hysteresis comparator A4 is fed back to the Miller integration circuit 122. For example, as shown in FIG.
Feedback to the Miller integration circuit 122 as in the figure,
The other one may be configured to feed back to the input terminal of the resistor R3 via the counter 125. The reason for passing through the counter 125 is to create a signal with a pulse width sufficiently longer than the time division frequency as an input, and as a result, e is added to the Miller integration circuit 122.

〔Effect of the invention〕

As described in detail above, according to the present invention, since the pulse width time division multiplication method is used, current can be integrated with high precision even during light loads and distorted waves, and linearity can also be improved. In addition, we can provide an integrating ammeter that can widen the magnitude range of voltage-frequency conversion circuits.

[Brief explanation of drawings]

Figure 1 is a block diagram of a conventional integrating ammeter, and Figure 2 is a block diagram of a conventional integrating ammeter.
The configuration diagram of the full-wave rectifier circuit in Figure 3 is similar to Figures 1 and 2.
4 is a block diagram of the integrating ammeter according to the present invention, and FIG. 5 is a diagram explaining the operation of FIG. A block diagram of a pulse width modulation type time division multiplication circuit. Fig. 6 is a block diagram showing other examples of a multiplication circuit. Circuit, 13...Low pass filter, I4...Voltage-frequency conversion circuit, 121...Constant double voltage generation circuit, 122...Miller integration circuit, A4...Hysteresis comparator, I24...Switch circuit , 125・
··counter.

Claims (2)

[Claims] (1) A constant that generates a constant multiplier voltage in an integrating ammeter that takes in and integrates a signal proportional to the current consumption of the power supply line by opening and closing control of a switch circuit, and converts the voltage obtained by this integration into a frequency. A double generation circuit, a Miller integrator circuit to which the constant double voltage of this circuit is input, and a converter that converts the integral output of this Miller integrator circuit and feeds the output back to the Miller integrator circuit to obtain the constant double voltage. 1. An integrating ammeter comprising: a comparator/lator for modulating pulse width and pulse width, and opening/closing of the switch circuit is controlled by an output signal of the comparator and an inverted signal of the output signal. (2) The integrating ammeter according to claim 1, wherein the constant multiplication generating circuit is not a counter, and inputs the output of the converter to the counter to obtain the constant multiplication voltage.