JPS64613Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an effective value conversion device capable of converting an input signal into a true effective value signal.

Conventional effective value converters have unstable operation with respect to input signals of zero or near zero.
The present invention provides an effective value conversion device that operates stably even when the input signal is zero.

FIG. 1 is a diagram showing an embodiment of the effective value conversion device of the present invention. In Figure 1, R ₁ to _{R 14} are resistors, C ₁ and C ₂ are capacitors, U ₁ to _{U 4} are amplifiers,
SW ₁ to _{SW 3} are analog switches (hereinafter simply referred to as switches) that are turned on when the signal applied to the on/off control terminal is at the HI level of “1” and turned off when the signal is at the LO level of “0”. It has the following functions. G ₁ and G ₂ are gates that invert the polarity of input signals, and D ₁ and D ₂ are diodes. IG is an integrator consisting of an input resistor R ₁ and an amplifier U ₁ having an integrating capacitor C ₁ , COM is a comparator with hysteresis characteristics consisting of resistors R ₂ and R ₃ and gates G ₁ and G ₂ , and F is a filter with low frequency passing characteristics, consisting of resistor R ₉ , capacitor C ₂ and amplifier U ₃
Consists of. A is resistance R ₁₀ to R ₁₄ and diode
D ₁ , D ₂ , nonlinear circuit consisting of amplifier U ₄ , B
is a feedback circuit that feeds back the signal at the output terminal 2 to the integrator IG via the nonlinear circuit A, and is composed of resistors R ₅ to R ₈ , switches SW ₂ and SW ₃ , and an amplifier U ₂ .

Input terminal 1 to which the input signal e _x is applied is a resistor
Amplifier U ₁ with integrating capacitor C ₁ through R ₁
connected to the switch via resistor _R4
Connected to the input terminal of SW ₁ . The output of the integrator IG is connected via a resistor R ₂ to a circuit in which gates G ₁ and G ₂ are connected in series. The output of gate _G2 is connected to the on/off control terminal of switch _SW1 , and is also connected to the input terminal of gate _G1 via resistor _R3 . Output terminal of switch SW ₁ (Figure 1 SW
The terminal (blacked out) is connected to the amplifier U ₃ that constitutes the filter F. A parallel circuit of a resistor R ₉ and a capacitor C ₂ is connected between the input and output of the amplifier U ₃ . The output of amplifier U ₃ is connected to output terminal 2 and to nonlinear circuit A. That is, output terminal 2 is connected to amplifier U ₄ via resistor R ₁₀ . Between the input and output of the amplifier U ₄ there is a resistor R ₁₁
A series circuit consisting of a resistor R 14 and a diode D ₁ is connected, and a series circuit consisting of a resistor R ₁₄ and a diode D ₂ is further connected to form a half-wave rectifier circuit. The polarity of the connection between diodes D ₁ and D ₂ is such that a negative signal is taken out from the connection point between resistor R ₁₁ and diode D ₁ , and a positive signal is taken out from the connection point between resistor R ₁₄ and diode D ₂ . It will be done.
If the connection point of resistor R ₁₁ and diode D ₁ is P, then P
The point is connected to circuit ground via a resistor R ₁₃ and to the negative voltage -V _E via a resistor R ₁₂ . Furthermore, point P is connected to the amplifier via feedback circuit B.
Connected to the input terminal of U ₁ . That is, the point P is connected to the amplifier U ₁ through a series circuit of the resistor R ₅ and the switch SW ₂ , and the polarity inverting amplifier U ₂
is connected to the amplifier U ₁ through a series circuit of resistor R ₈ and switch SW ₃ . Note that the switch SW ₂ is controlled on and off by the gate G ₁ , and the switch SW ₃ is controlled by the gate G ₂ .

The operation of the apparatus shown in FIG. 1 configured and connected in this manner will be described below.

A DC signal voltage _Ex is applied to input terminal 1,
A current _Ex /R ₁ is applied to the amplifier U ₁ via the resistor R ₁ . If the voltage at point P is -E _s , resistor R ₅ and switch SW ₂
The feedback current flowing through is equal to the value _-Es / _R5 , which is the voltage _-Es divided by the resistance _R5 . Further, resistors R ₆ and R ₇ are set to the same value, and constitute a polarity inverting circuit with amplifier U ₂ . Since resistor _R8 and resistor _R5 are set to equal values, the feedback current flowing through switch _SW3 is +
E _s /R ₅ . Amplifier U ₁ has an integration function by capacitor C ₁ , and the current E _x /R ₁ from input terminal 1 inputted to the summing point of U ₁ and +E _s /R 1 applied by switching switches SW ₂ and SW ₃ alternately. The apparatus shown in FIG. 1 operates so that the feedback currents of R ₅ and -E _s /R ₅ become zero in one period of integration. That is, the output voltage e ₁ of the amplifier U ₁ , the input voltage e ₂ of the gate G ₁ , and the output voltage e ₄ of the gate G ₂ are as shown in A, B, and C in FIG.
When a positive input current E _x /R ₁ and a negative feedback current −E _s /R ₅ (set to E _x /R ₁ −E _s /R ₅ <0) are applied to the amplifier U _1. , the output voltage e ₃ of the gate G ₁ is at HI level and the switch SW ₂ is turned on, and the output voltage e ₄ of the gate G ₂ is at the LO level and the switch SW ₃ is turned off. Since _the negative input of E _x /R ₁ −E _s /R ₅ is applied to the amplifier U ₁ , its output voltage e ₁ increases as shown in FIG. It increases as shown in Figure B. If the threshold voltage of gate G ₁ is V _s , the output voltage e ₃ of gate G ₁ is reversed from positive to negative voltage at voltage e ₂ = V _s , and therefore the output voltage e ₄ of gate G ₂ is negative. Positively reversed from . As a result, switch SW ₂ is turned off and SW ₃ is turned on, and a positive signal of E _x /R ₁ + E _s /R ₅ is applied to the summing point of amplifier U ₁ , so that voltage e ₁ decreases to a negative value. start. The voltage e ₂ shifts to a certain positive potential in synchronization with the change in the voltage e ₄ , but decreases as the voltage e ₁ decreases, and at the potential of e ₂ = V _s , the output voltage of the gate G ₁ e ₃ again flips from negative to positive, thus gate
The output voltage e ₄ of G ₂ flips from positive to negative. This kind of operation is repeated by the integrator IG and the comparator COM with hysteresis characteristics.As shown in Figure 2, if the period when the voltage _e4 is negative is _T1 , and the period when it is positive is _T2 . As mentioned above, in the device shown in FIG. 1, the average value of the input signal current E _x /R ₁ at the summing point of the amplifier U ₁ and the feedback current applied via the switches SW ₂ and SW ₃ ±E _s /R ₅ The following equation (1) holds true because it operates so that the value becomes zero.

E _x /R ₁・(T ₁ +T ₂ )＋E _s /R ₅・(T ₂ −T ₁ )=0 (1) If the resistances R ₁ and R ₅ are equal, then rearrange equation (1). can be rewritten as equation (2).

E _x /E _s = T ₁ - T ₂ / T ₁ + T ₂ (2) In other words, the average value of the pulse voltage of the output voltage e ₄ of gate G ₂ indicates E _x /E _s , but in this case, As is clear from FIG. 2C, since T ₁ >T ₂ , the actual average value of the output voltage e ₄ of the gate G ₂ shows a negative value of −E _x /E _s .

Further, the gate _G2 and the switch _SW1 constitute a multiplier M. That is, the output current I ₁ of switch SW ₁
is, the amplitude of the pulse is proportional to the input signal voltage _Ex ,
The pulse width is represented by a signal proportional to E _x /E _s , and formula (3) holds true.

I ₁ = −E _x ² /R ₄・E _s (3) The current I ₁ shown by equation (3) is input to filter F,
As a result, an output signal e _p expressed by equation (4) is obtained from the output end of the filter F.

e _p =K ₁ /E _s ∫E _x ² dt (4) K ₁ : Constant The output signal e _p is input to the nonlinear circuit A, and the voltage E _s shown by equation (5) is taken out from point P.

E _s =K ₂ ·e _p (5) K ₂ : Constant From equations (4) and (5), the output signal e _p is expressed by equation (6).

In this way, the output signal e _p is the input DC signal voltage E _x
shows the effective value corresponding to When an alternating current signal e _x is input instead of the direct current signal voltage E _x , if the frequency of the integral shown in Figure 2 is higher than the frequency of the alternating current signal e _x , the input voltage is instantaneously regarded as direct current as described above. Therefore, the output signal e _p shows an effective value even for the alternating current signal e _x .

In the device of FIG. 1 operating in this manner, when the input signal e _x decreases, the output signal e _p also decreases, and therefore the voltage E _s at point P also decreases. For example, when the value of the input signal e _x is e ₅ , the value of the output signal e _p is e ₆ , then,
When the voltage E _s reaches the value shown by equation (7), the diode D ₁ is turned off.

E _s =−V _E ·R ₁₃ /R ₁₂ +R ₁₃ (7) On the other hand, since the output signal e _p is the effective value shown by equation (6), it is at a positive potential and the diode D ₂ is also off. In this way, since diodes D ₁ and D ₂ are off, the potential at point P is the voltage −V _E expressed by equation (7),
It is clamped by the values of resistors R ₁₂ and R ₁₃ . Therefore P
The relationship between the voltage E _s at the point and the output signal e _p is as shown in FIG. From the above, when the value of the input signal e _x is smaller than e ₅ , regardless of the value of the output signal e _p , (7)
A constant voltage given by the equation is applied to amplifier U ₁ via switches SW ₂ and SW ₃ . Therefore the input signal e _x
is zero, the integrator IG is connected to switch SW ₂ and
The feedback current due to the voltage shown in equation (7), which is applied alternately by SW ₃ , is integrated, and the average value of the positive and negative feedback currents input to the summing point of amplifier U ₁ becomes zero in one cycle of integration. switch to become
Drive SW ₂ and SW ₃ . That is, T ₁ and T ₂ shown in FIG. 2C become equal, and the output signal e _p becomes zero. Furthermore, when the absolute value of the input signal e _x is smaller than e ₅ , E _s on the right side of equation (4) becomes a constant, and therefore the output signal e _p at this time changes according to the relationship expressed by equation (8). do.

e _p = K ₃・∫e _x ² dt (8) K ₃ : Constant Figure 4 shows the relationship between the input signal e _x and the output signal e ₀ in the device shown in Figure 1, but as mentioned above, When the input signal e _x is larger than e ₅ (normal input voltage level), the relationship is expressed by equation (6), and when the input signal e _x is smaller than e ₅ (the input signal e _x is near 0 V) ) shows that the relationship is as shown in equation (8).

In this way, according to the present invention, when the input signal e _x becomes a small input below a certain level, a preset constant voltage is applied to the integrator IG, so stable operation is achieved at any input voltage. It is possible to realize an effective value conversion device of
The effect is extremely large. In addition, the fourth
In the figure, the error in effective value conversion increases when the value of the input signal e _x is smaller than _e5 , but generally when the input signal e _x is near 0V, which is much smaller than the rated input value, Since there are very few cases where the accuracy of effective value conversion becomes a problem, there is no problem even if it is put into practical use.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the effective value conversion device according to the present invention, FIG. 2 is a diagram showing waveforms of various parts of the device in FIG. 1, and FIG. 3 is an output signal e _p of the device in FIG. 1.
Figure 4 shows the relationship between the voltage E _{s at point P and the voltage E s} at point P.
FIG. 3 is a diagram showing the relationship between an input signal e _x and an output signal e _p in the device shown in FIG. R ₁ ~ R ₁₄ ... Resistor, C ₁ , C ₂ ... Capacitor, U ₁
~ _U4 ...Amplifier, _SW1 ~ _SW3 ...Switch, _G1 ,
G ₂ ... Gate, D ₁ , D ₂ ... Diode, IG ...
Integrator, COM...Hysteresis comparator,
F...filter, M...multiplier, B...feedback circuit, A...nonlinear circuit.

Claims (1)

[Scope of utility model registration request] an integrator that integrates an input signal and a signal fed back from an output signal; a comparator that has hysteresis characteristics that is driven by the output of the integrator; and a multiplier that multiplies the output of the comparator that has hysteresis characteristics and the input signal. In the device, the apparatus includes a filter that converts the output of the multiplier into a DC current, and a feedback circuit that feeds back the output signal to the integrator, when the output signal is at a predetermined level or higher, the magnitude of the output signal is A non-linear circuit that outputs a proportional signal and outputs a signal at a constant level when the output signal is below the predetermined level is connected between the filter and the feedback circuit. Value conversion device.