CN202794317U - Zero cross detection circuit structure - Google Patents

Abstract

The utility model relates to a zero cross detection circuit structure, belonging to the circuit structure technology field. The circuit structure comprises a current bias circuit module and a three-stage grounded emitter-stage amplification circuit module which are both connected with a power supply, and a zero cross detection input end and a zero cross detection output end are both connected with the three-stage grounded emitter-stage amplification circuit module. Compared with a single-stage grounded emitter amplifier in the conventional technology, the input voltage of the three-stage grounded emitter-stage amplification circuit module is reduced substantially, thereby improving the zero cross detection accuracy and effectively shortening the rising and falling times of a zero cross detection output signal. Meanwhile, the zero cross detection circuit structure also comprises a protection circuit module connected between the three-stage grounded emitter-stage amplification circuit module and the zero cross detection input end, thereby effectively reducing the voltage of a zero cross detection input signal. Moreover, the zero cross detection circuit structure of the utility model is simple in structure, low in cost, simple and convenient in installation and debugging and wider in application range, and needs fewer peripheral elements.

Description

The zero cross detection circuit structure

Technical field

The utility model relates to the circuit structure technical field, and particularly the testing circuit technical field specifically refers to a kind of zero cross detection circuit structure.

Background technology

In the existing household electrical appliance, automatically controlled part has the components and parts such as relay, controllable silicon basically.Under high pressure repeatedly adhesive, disconnection or controllable silicon repeatedly conducting, cut-off under high pressure of relay can produce a large amount of electromagnetic interference signals, can greatly reduce simultaneously relay, silicon controlled serviceable life.Need a kind of testing circuit to control the current potential of its adhesive, disconnection for this reason, its handoff procedure is carried out near zero-point voltage, with the minimizing electromagnetic interference (EMI), and the serviceable life of improving components and parts.

Chinese patent 201020625970.8 has been announced a kind of zero cross detection circuit.Its equivalent circuit diagram as shown in Figure 1.By the sample current potential of electrical network of diode rectifier bridge and divider resistance, triode is connected into the grounded emitter amplifier form, the base stage of sampled signal input triode, and the collector of triode connects and draws resistance, and transistor collector is as the output of zero cross detection circuit.When sampled signal is lower than 0.7V, transistor collector output high level signal.

Above-mentioned patent adopts discrete device to realize zero crossing detection function, has following shortcoming:

1, affected by the parameter discrete of discrete device, such as the difference of the forward conduction voltage of the error of resistance value, triode BE knot, it is very accurate that zero crossing can not be done.

2, owing to adopt a plurality of discrete devices, this zero cross detection circuit can take certain pcb board area, the inconvenience of bringing also for the Installation and Debugging of circuit.

3, adopt a triode single-stage to amplify, open-loop gain is lower, and the zero passage detection output signal rises, fall time can be long, is not suitable for frequency applications.

4, do not have holding circuit, when line voltage was higher, the transistor base electric current can be excessive.

The utility model content

The purpose of this utility model is to have overcome above-mentioned shortcoming of the prior art; provide that a kind of can effectively to solve in the prior art zero crossing out of true, rise time long and do not have a problem such as holding circuit; and circuit structure is simple; with low cost; the circuit peripheral cell of required employing is less; Installation and Debugging are easy, the zero cross detection circuit structure that has wide range of applications.

In order to realize above-mentioned purpose, zero cross detection circuit structure of the present utility model has following formation:

This circuit structure comprises current biasing circuit module and three grades of cascode level amplifying circuit modules, described current biasing circuit module with are connected a grade cascode level amplifying circuit module and all connect power supply VCC, the zero passage detection input end of this zero cross detection circuit structure is connected with the zero passage detection output terminal and is connected described three grades of cascode level amplifying circuit modules.

In this zero cross detection circuit structure, described current biasing circuit module comprises a NPN triode N1, the first resistance R 1, the second resistance R 2, the 3rd resistance R 3 and a PNP triode P1; Described the first resistance R 1 and the second resistance R 2 are series between described power supply VCC and the ground, the tie point of the first resistance R 1 and 2 of the second resistance R links to each other with the base stage of a described NPN triode N1, one end of described the 3rd resistance R 3 connects the emitter of a described NPN triode N1, the 3rd resistance R 3 other end ground connection, the collector of a described PNP triode P1 and base stage short circuit, and connect the collector of a described NPN triode N1; The emitter of a described PNP triode P1 connects power supply VCC, and the base stage of a PNP triode P1 also connects described three grades of cascode level amplifying circuit modules.

In this zero cross detection circuit structure, described three grades of cascode level amplifying circuit modules comprise the 2nd NPN triode N2, the 3rd NPN triode N3, the 4th NPN triode N4, the 4th resistance R 4, the 2nd PNP triode P2 and the 3rd PNP triode P3; The emitter of described the 2nd PNP triode P2 and the 3rd PNP triode P3 all connects described power supply VCC, and the 2nd PNP triode P2 and the base stage of the 3rd PNP triode P3 all connect the base stage of a described PNP triode P1; One end of described the 4th resistance R 4 also connects described connection power supply VCC, and its other end connects the collector of described the 2nd NPN triode N2, and the collector of described the 2nd NPN triode N2 also connects described zero passage detection output terminal; The collector of the base stage of described the 2nd NPN triode N2, described the 3rd NPN triode N3 collector and described the 2nd PNP triode P2 interconnects; The base stage of the collector of the collector of described the 4th NPN triode N4, described the 3rd PNP triode P3 and described the 3rd NPN triode N3 interconnects; The equal ground connection of emitter of described the 2nd NPN triode N2, the 3rd NPN triode N3 and the 4th NPN triode N4; The base stage of described the 4th NPN triode N4 connects described zero passage detection input end.

In this zero cross detection circuit structure, described circuit structure also comprises the holding circuit module, and described holding circuit module is connected between described three grades of cascode level amplifying circuit modules and the described zero passage detection input end.

In this zero cross detection circuit structure, described holding circuit module comprises the 5th NPN triode N5, diode D1 and the 5th resistance R 5; The collector of described the 5th NPN triode N5 is connected with the anode of described diode D1, and connects described zero passage detection input end; The base stage of the base stage of the 5th NPN triode N5, the negative electrode of described diode D1, described the 4th NPN triode N4 and an end of described the 5th resistance R 5 interconnect; The equal ground connection of emitter of the other end of the 5th resistance R 5 and described the 5th NPN triode N5.

In this zero cross detection circuit structure, described circuit structure also comprises current-limiting resistance R6 and commutation diode D2, described zero passage detection input end connects the negative electrode of described commutation diode D2, the anodic bonding external electrical network voltage of described commutation diode D2 by described current-limiting resistance R6.

Adopted the zero cross detection circuit structure of this utility model, it comprises current biasing circuit module and the three grades of cascode level amplifying circuit modules that all connect power supply, and the zero passage detection input end of this zero cross detection circuit structure is connected with the zero passage detection output terminal and is connected described three grades of cascode level amplifying circuit modules.The input voltage of three grades of cascode level amplifying circuit modules changes single-stage grounded emitter amplifier more of the prior art and significantly reduces, thereby can improve the accuracy that zero crossing detects, and effectively shortens the rising and falling time of zero passage detection output signal.Further the zero cross detection circuit structure of this utility model also comprises the holding circuit module that is connected between three grades of cascode level amplifying circuit modules and the zero passage detection input end; thereby effectively reduce the voltage that zero crossing detects input signal, provide protection to zero cross detection circuit.And zero cross detection circuit structure of the present utility model, it is simple in structure, and is with low cost, and the circuit peripheral cell of required employing is less, and Installation and Debugging are easy, and range of application is also comparatively extensive.

Description of drawings

Fig. 1 is the equivalent circuit diagram of a kind of zero cross detection circuit of the prior art.

Fig. 2 is the circuit diagram of zero cross detection circuit structure of the present utility model.

Fig. 3 is that the small-signal of three grades of cascode amplifier sections in the zero cross detection circuit structure of the present utility model exchanges isoboles.

Fig. 4 is zero passage detection input signal and the signal output waveform figure of zero cross detection circuit structure of the present utility model.

Fig. 5 is that zero cross detection circuit structure of the present utility model connects the peripheral applications synoptic diagram.

Embodiment

In order more clearly to understand the technology page of the present utility model, describe in detail especially exemplified by following examples.

See also shown in Figure 2ly, be the circuit diagram of zero cross detection circuit structure of the present utility model.

In one embodiment, this circuit structure comprises current biasing circuit module and three grades of cascode level amplifying circuit modules, described current biasing circuit module with are connected a grade cascode level amplifying circuit module and all connect power supply VCC, the zero passage detection input end of this zero cross detection circuit structure is connected with the zero passage detection output terminal and is connected described three grades of cascode level amplifying circuit modules.

In a kind of more preferably embodiment, described current biasing circuit module comprises a NPN triode N1, the first resistance R 1, the second resistance R 2, the 3rd resistance R 3 and a PNP triode P1; Described the first resistance R 1 and the second resistance R 2 are series between described power supply VCC and the ground, the tie point of the first resistance R 1 and 2 of the second resistance R links to each other with the base stage of a described NPN triode N1, one end of described the 3rd resistance R 3 connects the emitter of a described NPN triode N1, the 3rd resistance R 3 other end ground connection, the collector of a described PNP triode P1 and base stage short circuit, and connect the collector of a described NPN triode N1; The emitter of a described PNP triode P1 connects power supply VCC, and the base stage of a PNP triode P1 also connects described three grades of cascode level amplifying circuit modules.

In a kind of further preferred embodiment, described three grades of cascode level amplifying circuit modules comprise the 2nd NPN triode N2, the 3rd NPN triode N3, the 4th NPN triode N4, the 4th resistance R 4, the 2nd PNP triode P2 and the 3rd PNP triode P3; The emitter of described the 2nd PNP triode P2 and the 3rd PNP triode P3 all connects described power supply VCC, and the 2nd PNP triode P2 and the base stage of the 3rd PNP triode P3 all connect the base stage of a described PNP triode P1; One end of described the 4th resistance R 4 also connects described connection power supply VCC, and its other end connects the collector of described the 2nd NPN triode N2, and the collector of described the 2nd NPN triode N2 also connects described zero passage detection output terminal; The collector of the base stage of described the 2nd NPN triode N2, described the 3rd NPN triode N3 collector and described the 2nd PNP triode P2 interconnects; The base stage of the collector of the collector of described the 4th NPN triode N4, described the 3rd PNP triode P3 and described the 3rd NPN triode N3 interconnects; The equal ground connection of emitter of described the 2nd NPN triode N2, the 3rd NPN triode N3 and the 4th NPN triode N4; The base stage of described the 4th NPN triode N4 connects described zero passage detection input end.

A kind of further preferred embodiment in, described circuit structure also comprises the holding circuit module, described holding circuit module is connected between described three grades of cascode level amplifying circuit modules and the described zero passage detection input end.Described holding circuit module comprises the 5th NPN triode N5, diode D1 and the 5th resistance R 5; The collector of described the 5th NPN triode N5 is connected with the anode of described diode D1, and connects described zero passage detection input end; The base stage of the base stage of the 5th NPN triode N5, the negative electrode of described diode D1, described the 4th NPN triode N4 and an end of described the 5th resistance R 5 interconnect; The equal ground connection of emitter of the other end of the 5th resistance R 5 and described the 5th NPN triode N5.

In a kind of preferred embodiment, described circuit structure also comprises current-limiting resistance R6 and commutation diode D2, described zero passage detection input end connects the negative electrode of described commutation diode D2, the anodic bonding external electrical network voltage of described commutation diode D2 by described current-limiting resistance R6.

In the application of reality, zero cross detection circuit structure of the present utility model comprises voltage gain part, protection part, the zero crossing determining section of current offset part, three grades of grounded emitter amplifiers, 4 parts.

One, the generating portion of current offset.

The current offset part is in order to produce the PNP mirror currents, and the PNP current mirror is as the active load of cascode amplifier stage.Supply voltage VCC is after resistance R 1, R2 dividing potential drop, as the base bias voltage of NPN triode N1.This voltage deducts the pressure drop that namely obtains after the N1 pipe BE knot forward voltage drop (about 0.7V) on the resistance R 3.Voltage drop on the resistance R 3 can be tried to achieve the emitter current of N1 pipe divided by the resistance of resistance R 3, is designated as I1.The computing formula of I1 is:

$I1=\frac{R2}{R3(R1+R2)}\mathrm{VCC}-\frac{0.7}{R3}$

Because the current amplification factor of N1 is larger, the emitter current of N1 and collector current can be thought approximately equal.Then the collector current of P1 just equals I1.Because P1, P2, P3 form the image current mirror, then collector current I2, the I3 of P2, P3 can try to achieve by the launch site Area Ratio that calculates P1, P2, P3.

$I2=\frac{A2}{A1}I1;$ $I3=\frac{A3}{A1}I1$

Wherein, A1 is the launch site area of P1, and A2 is the launch site area of P2, and A3 is the launch site area of P3.I2, I3 also are the collector currents of N3, N4 simultaneously.

Two, the voltage gain part of three grades of grounded emitter amplifiers.

The small-signal of three grades of cascode amplifier sections exchanges isoboles as shown in Figure 3.

The grounded emitter amplifier gain that N4 forms is: $\frac{v1}{\mathrm{vin}}=-\mathrm{gm}4\×\frac{1}{\mathrm{gc}4+\mathrm{gce}4+\mathrm{gbe}3}.$

The grounded emitter amplifier gain that N3 forms is: $\frac{v2}{v1}=-\mathrm{gm}3\×\frac{1}{\mathrm{gc}3+\mathrm{gce}3+\mathrm{gbe}2}.$

The grounded emitter amplifier gain that N2 forms is: $\frac{\mathrm{vout}}{v2}=-{\mathrm{\β}}_2\frac{1}{\mathrm{rbe}2(g4+\mathrm{gce}2)}.$

In the following formula, gm4, gm3 are the mutual conductances of N4, N3,

K is Boltzmann constant, and T is kelvin degree, and q is elementary charge.V _TValue (300k) about 25.9mV when normal temperature.

Gc4 is that N4 collector series electrical is led,

V _P3It is the vertical magnitude of voltage of strategic point of P3.Gce4 is N4 pipe collector-emitter equivalent conductance, V _N4It is the vertical magnitude of voltage of strategic point of N4.Gbe3 is N3 base-emitter equivalent conductance,

β ₃It is the current amplification factor of N3 pipe.

Same, gc3 is that N3 collector series electrical is led,

V _P2It is the vertical magnitude of voltage of strategic point of P2.Gce3 is N3 pipe collector-emitter equivalent conductance,

V _N3It is the vertical magnitude of voltage of strategic point of N3.Gbe2 is N2 base-emitter equivalent conductance,

β ₂The current amplification factor of N2 pipe, I _CIt is N2 pipe collector electric current.

G4 is that the electricity of R4 is led.Gce2 is the collector-emitter equivalent conductance of N2 pipe.

V _N2It is the vertical magnitude of voltage of strategic point of N2.

The full gain of three grades of cascode amplifier sections is products of N2, N3, N4 gain, is shown below:

$\frac{\mathrm{vout}}{\mathrm{vin}}=-{\mathrm{\β}}_3{\mathrm{\β}}_4\frac{I_{C}R4V_{N2}}{V_T{V}_{N2}+I_C{V}_T}\·\frac{V_{P2}{V}_{N3}}{V_{N3}{\mathrm{\β}}_3{V}_T+V_{P2}{\mathrm{\β}}_3{V}_T+V_{P2}{V}_{N3}}\·\frac{V_{P3}{V}_{N4}}{V_{N4}{\mathrm{\β}}_4{V}_T+V_{P3}{\mathrm{\β}}_4{V}_T+V_{P3}{V}_{N4}}$

And adopt the zero passage holding circuit voltage gain of single-stage grounded emitter amplifier to be:

Be equivalent to the gain of N2 pipe, much smaller than the voltage gain of three grades of cascodes amplifications.

Therefore, the meaning of increase voltage gain is.When zero passage detects the same magnitude of voltage of exporting change.The input voltage that three grades of cascodes amplify changes can be little more a lot of than single-stage grounded emitter amplifier, the rising of zero passage detection output signal, can do fall time very little.The zero passage detection input signal of zero cross detection circuit structure of the present utility model and signal output waveform figure such as Fig. 4 are.

Three, protection part.

Act on the base stage of N5 behind the zero passage detection input signal process diode D1.N5 is connected into negative feedback mode.When zero passage detected the input signal increase, the N5 base input signal increased, and the N5 collector voltage reduces, thereby reduced the zero passage detection input signal.The zero passage detection input end generally is stabilized in 1.4V.

Four, zero crossing determining section.

As shown in Figure 5, zero cross detection circuit of the present utility model only needs an external current-limiting resistance R6 and commutation diode D2, can directly get access to grid.When line voltage is higher, the zero cross detection circuit output low level.When line voltage is reduced to zero crossing, zero passage detection output high level.Select different R6 resistance values, can change the size of zero crossing.The computing formula of zero crossing voltage is:

V _ZERO＝V _D1+V _R5+V _D2+V _R6，

The about 0.7V of the voltage of D1, R5, D2, the voltage V on the R6 _R6For:

$V_{R6}=R6(I_{R5}+I5)=R6(\frac{0.7}{R5}+\frac{A5}{A4}I3).$

Wherein, I _R5Be the electric current on the resistance R 5, because R5 is connected between N5 base stage, the emitter, about 0.7V falls in its both end voltage; I5 is the collector current of N5, because N4 links to each other with the N5 base stage, the collector current I5 of N5 and the collector current I3 of N4 are proportional,

A5, A4 are the launch site area of N5, N4.

Adopted the zero cross detection circuit structure of this utility model, it comprises current biasing circuit module and the three grades of cascode level amplifying circuit modules that all connect power supply, and the zero passage detection input end of this zero cross detection circuit structure is connected with the zero passage detection output terminal and is connected described three grades of cascode level amplifying circuit modules.The input voltage of three grades of cascode level amplifying circuit modules changes single-stage grounded emitter amplifier more of the prior art and significantly reduces, thereby can improve the accuracy that zero crossing detects, and effectively shortens the rising and falling time of zero passage detection output signal.Further the zero cross detection circuit structure of this utility model also comprises the holding circuit module that is connected between three grades of cascode level amplifying circuit modules and the zero passage detection input end; thereby effectively reduce the voltage that zero crossing detects input signal, provide protection to zero cross detection circuit.And zero cross detection circuit structure of the present utility model, it is simple in structure, and is with low cost, and the circuit peripheral cell of required employing is less, and Installation and Debugging are easy, and range of application is also comparatively extensive.

In this instructions, the utility model is described with reference to its specific embodiment.But, still can make various modifications and conversion obviously and not deviate from spirit and scope of the present utility model.Therefore, instructions and accompanying drawing are regarded in an illustrative, rather than a restrictive.

Claims (6)

1. zero cross detection circuit structure, it is characterized in that, described circuit structure comprises current biasing circuit module and three grades of cascode level amplifying circuit modules, described current biasing circuit module with are connected a grade cascode level amplifying circuit module and all connect power supply (VCC), the zero passage detection input end of this zero cross detection circuit structure is connected with the zero passage detection output terminal and is connected described three grades of cascode level amplifying circuit modules.

2. zero cross detection circuit structure according to claim 1, it is characterized in that described current biasing circuit module comprises a NPN triode (N1), the first resistance (R1), the second resistance (R2), the 3rd resistance (R3) and a PNP triode (P1); Described the first resistance (R1) and the second resistance (R2) are series between described power supply (VCC) and the ground, the first resistance (R1) links to each other with the base stage of a described NPN triode (N1) with tie point between the second resistance (R2), one end of described the 3rd resistance (R3) connects the emitter of a described NPN triode (N1), the 3rd resistance (R3) other end ground connection, the collector of a described PNP triode (P1) and base stage short circuit, and connect the collector of a described NPN triode (N1); The emitter of a described PNP triode (P1) connects power supply (VCC), and the base stage of a PNP triode (P1) also connects described three grades of cascode level amplifying circuit modules.

3. zero cross detection circuit structure according to claim 2, it is characterized in that described three grades of cascode level amplifying circuit modules comprise the 2nd NPN triode (N2), the 3rd NPN triode (N3), the 4th NPN triode (N4), the 4th resistance (R4), the 2nd PNP triode (P2) and the 3rd PNP triode (P3); The emitter of described the 2nd PNP triode (P2) and the 3rd PNP triode (P3) all connects described power supply (VCC), and the 2nd PNP triode (P2) and the base stage of the 3rd PNP triode (P3) all connect the base stage of a described PNP triode (P1); One end of described the 4th resistance (R4) also connects described connection power supply (VCC), its other end connects the collector of described the 2nd NPN triode (N2), and the collector of described the 2nd NPN triode (N2) also connects described zero passage detection output terminal; The collector of the base stage of described the 2nd NPN triode (N2), described the 3rd NPN triode (N3) collector and described the 2nd PNP triode (P2) interconnects; The base stage of the collector of the collector of described the 4th NPN triode (N4), described the 3rd PNP triode (P3) and described the 3rd NPN triode (N3) interconnects; The equal ground connection of emitter of described the 2nd NPN triode (N2), the 3rd NPN triode (N3) and the 4th NPN triode (N4); The base stage of described the 4th NPN triode (N4) connects described zero passage detection input end.

4. zero cross detection circuit structure according to claim 3; it is characterized in that; described circuit structure also comprises the holding circuit module, and described holding circuit module is connected between described three grades of cascode level amplifying circuit modules and the described zero passage detection input end.

5. zero cross detection circuit structure according to claim 4 is characterized in that, described holding circuit module comprises the 5th NPN triode (N5), diode (D1) and the 5th resistance (R5); The collector of described the 5th NPN triode (N5) is connected with the anode of described diode (D1), and connects described zero passage detection input end; One end of the base stage of the negative electrode of the base stage of the 5th NPN triode (N5), described diode (D1), described the 4th NPN triode (N4) and described the 5th resistance (R5) interconnects; The equal ground connection of emitter of the other end of the 5th resistance (R5) and described the 5th NPN triode (N5).

6. each described zero cross detection circuit structure in 5 according to claim 1, it is characterized in that, described circuit structure also comprises current-limiting resistance (R6) and commutation diode (D2), described zero passage detection input end connects the negative electrode of described commutation diode (D2), the anodic bonding external electrical network voltage of described commutation diode (D2) by described current-limiting resistance (R6).

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