JPS594291Y2 - Electricity detection device - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an electricity detection device for detecting whether an input quantity of electricity is greater than or equal to a predetermined value, and particularly relates to a detection device for an alternating current quantity of electricity.

Conventionally, a simple electric quantity detection device detects whether the input is above a predetermined value by determining, for example, whether the period during which the full-wave rectified wave of the AC input is above a predetermined value is longer than a predetermined time determined by a time constant. The common method was to

To explain this according to the block diagram in Fig. 1 and the waveform diagram in Fig. 2, ■ is the input electrical quantity that is applied to the full-wave rectifier circuit 1 from the input terminal a1, and the circuit output ■ 1o is a predetermined value ■ 0 or more. When the output V20 is taken out from the level detection circuit 2,
Timer T1 outputs V.

1 and is output to the output terminal a2 through the timer T2. At this time, the timer T□ is a timer with an operating time T1 and a return time of zero, and the timer T2 is a timer with an operating time of zero 1 and a return time T2.

The operation of FIG. 1 will be explained using the waveform diagram of FIG. 2.

A is when the input ■ is small, and an input is when the human power V is large. First, in the case of A, since the output time width tll of the level detection circuit 2 is shorter than the judgment time T1 of the timer T1, the timer T1
There is no output from the output terminal a2.

Also, in the same way, since the output time width t1□ of the level detection circuit 2 is longer than the judgment time T1 of the timer T1, the timer T
1, a pulse output with a time width of (j12 Tl) is generated once per cycle, and is made continuous by timer T2,
Continuous output is output from output terminal a2.

Therefore, it is necessary to set T2-+10α (α is the margin time), and for example, it is set to T2-1 cycle.

Furthermore, the detected values of the circuit of FIG. 1 in FIG. 3A will be explained.

In this case, if T1=2 and the detection level of the level detection circuit 2 is VL, then the following equation is obtained, and it can be seen that whether or not the effective value of the input electric quantity is larger than ■ is detected.

In this way, the conventional device shown in Fig. 1 can detect whether or not the value is above a predetermined value, but since the judgment time T1 in Fig. 1 is constant regardless of the input frequency, the detected value changes if the input frequency changes. It's going to change.

For example, if the input frequency f' changes to f' = m with respect to the rated frequency f, it was T1 - %f at the rated frequency f, but for w, it corresponds to T1 = ÷ in electrical angle. Therefore, as shown in Figure 3, the detection conditions at this time are: The detected value is .

That is, about 77% of the detected values when the rated frequency f is human, and the detected values when the force frequency f = 7, resulting in extremely poor frequency characteristics.

In consideration of the drawbacks of conventional devices in that the time constant does not change even when the input frequency changes and the frequency characteristics are poor, the present invention provides an electrical quantity detection device in which the detected value does not change in principle.

FIG. 4 is a block diagram showing the principle of this invention. As in the case of FIG. Output V30
Also, the sorting device 4 detects a period t1 of 1 or more and outputs an output V40.

Also, 5 is a pulse generation circuit that generates a pulse at the zero point of the input V, and its output is ■.

is applied to the integrator 6 through the timer 7, and directly to one input terminal of the AND circuit AN.

7 is a timer that delays the output of 5 by a minute time, and the output V60 of the integrator 6 is sent to the AND circuit A via the level detector 8.
It is applied as one input terminal of N, and its output VAN is taken out to output terminal a2 through timer T2.

FIG. 6 is a specific example of the integrator 6 shown in FIG. 4, which includes transistors Tri and Tr2, and the base of the transistor Tri has input terminals a3. Inputs V3o and V4O from a4 are applied through resistors R1 and R2.

A capacitor C is connected between the collector and base of the transistor Tri, and a DC power supply voltage E is applied to the collector of the transistor Tr□ via a resistor R3, and a DC power supply voltage -E is applied to the emitter.

The input V70 is applied to the base of the transistor Tr2 from the input terminal a5 through the resistor R4.

The collector of the transistor Tr2 is connected to the collector of the transistor Trl, and the output is taken out from the output terminal a6 as an output 6o.

Further, the emitter of the transistor Tr2 is grounded to the zero point.

FIG. 7 is an explanatory diagram using the waveforms of FIG. 6.

Thus, FIG. 6 operates as follows.

First, pulse ■7o is applied to the base of transistor Tr□, so that the reference value (OV in this case) is changed to V
2O is returned.

Next, when the input V30 is applied to the input terminal a3, the charge in the capacitor C is discharged with a constant current toward -E.

On the other hand, when the input V40 is applied to the input terminal a4, the capacitor C is charged with a constant current toward +E.

Here, transistor Tr□, capacitor C9 resistor Rt,
The circuits R2 and R3 are so-called Miller integration circuits.

Next, the operation shown in FIG. 4 will be explained in conjunction with the waveform diagram shown in FIG. 5.

First, when the input ■ is below a predetermined value, the output time width t of the sorting device 3 which detects the period when the input ■ is below the predetermined value ■1 is 21=t
Since 21+t2□8 is longer than the output time width t2□ of the dividing device 4 that detects the period of 1 or more, the output Vso of the integrator 6 becomes negative A as shown in the left half of the time axis t. There is no output from level detector 8.

Also, the output of integrator 6■.

is set by the output of the pulse generation circuit 5, and the minute timer 7
The point is returned to 0 periodically (once in +■) throughout.

Next, when the input ■ is greater than the predetermined value, the input ■ is the predetermined value VL
The period t1□ is ■, and the period t2□=t2□ is
It is longer than A0t22B, and the output of integrator 6 ■6o
becomes a positive value as shown in the right half of the time axis t.

Therefore, one pulse output is generated at the positive end of the level detector 8, as shown by 8o.

When the input V is at zero point, the pulse generation circuit 5 periodically outputs (+
A pulse (once per Hz) is generated, and when the pulse is present, an output is generated from the level detector 8, an output is output from the AND circuit AN, and the signal is made continuous by the timer T2 and output from the output terminal a.
2, the output is taken out.

The minute time timer 7 is a time coordination timer for returning the output of the integrator 6 to the reference value O after reliable detection (continuation) by the timer T2, and is set to a time of about 10 μs, for example.

Thus, the detection limit point in FIG. 5 is at the period t2 during which the input V is equal to or higher than the predetermined level or lower than the period t1, when t1=
This is when t2=7, and the detected value is the same as in the conventional device shown in FIGS. 1 and 2.

However, in the conventional device, detection is performed based on whether the period t1 during which the input ■ is equal to or higher than the predetermined level VL is greater than a certain period T1, so when the input frequency changes, the detected value changes significantly. However, in this invention, since tl and t2 are compared, the detected value does not change in principle even if the input frequency changes.

Further, in FIG. 4, charging is performed during period t1 and discharging is performed during period t2, but it is also possible to perform discharging during tl and charging during t2, depending on the application.

In addition, once the operating force is generated from the AND circuit AN, the output cloth is output to the output terminal a2, but in some cases, the AND circuit AN
It goes without saying that a more stable detector can be obtained by providing an output n times and outputting the output to the output terminal a2.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional electric quantity detection device, Figure 2 is a waveform diagram explaining Figure 1, Figure 3 is a waveform diagram explaining the detected values in Figure 1, and Figure 4 is a waveform diagram explaining the detected values in Figure 1. A block diagram showing an embodiment of this invention, FIG. 5 is a waveform diagram explaining FIG. 4, FIG. 6 is a circuit connection diagram showing an example of an integrator used in this invention, and FIG. It is a waveform diagram explaining a figure. In the figure, V is the input electricity amount, 1 is the full-wave rectifier circuit, 8 is the level detection circuit, T2.7 is the timer, a2 is the output terminal, 3,
4 is a period t1. during which the input V is greater than or equal to a predetermined value. 5 is a zero point pulse generation circuit, 6 is an integrator,
AN is an AND circuit. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] a first sorting device that rectifies the input AC quantity of electricity V and detects a first period in which the magnitude of the instantaneous value is less than or equal to a predetermined level VL; A sorting device, a pulse generation circuit that generates a pulse at the zero point of the input electric quantity (■), and outputs from the first and second sorting devices and the pulse generation circuit to the timer are applied respectively, and the second period an integrator that is charged or discharged during the first period and discharged or charged during the first period; and a level detector that determines whether the output voltage of the integrator is above or below a certain value; Quantity of electricity detection, characterized in that it detects whether the magnitude of the quantity of alternating current electricity (■) is below or above a predetermined value based on the output of the level detector at the time when the circuit has an output. Device.