CN113630108A - Triangular wave signal parameter measurement circuit - Google Patents

Abstract

The invention discloses a triangular wave signal parameter measuring circuit, which comprises a voltage reference V_ref1And V_ref2A circuit, a comparison circuit and a capture circuit; the voltage reference V_ref1And V_ref2A circuit for generating a voltage reference with high precision and high stability, the comparison circuit realizes the triangular wave signal v to be measured_tri(t) and V_ref1And V_ref2Comparing to obtain PWM signals

And

the capture circuit is to

And

are respectively connected to the controlThe invention discloses a Capture port Capture1 and Capture2 for manufacturing a chip, which have the characteristics of simple hardware structure, low cost and strong anti-interference capability.

Description

Triangular wave signal parameter measurement circuit

Technical Field

The invention relates to the field of signal measurement, in particular to a triangular wave signal parameter measuring circuit.

Background

The triangular wave signal is widely applied to occasions such as instruments and meters, digital audio systems, power electronics, radars, communication and the like, plays an important role in signal modulation application, and the performance of the triangular wave signal is a key index of a modulator.

The main parameter indexes of the triangular wave signal comprise amplitude, period, symmetry and the like. Where symmetry refers to the percentage of time that the triangular wave rise time occupies in the entire signal period. The existing triangular wave signal generation has three types: the first is to adopt discrete components to generate a mode based on waveform transformation, namely, triangular waves are generated by charging and discharging rectangular waves; the second is based on DDS technology mode, namely direct frequency synthesis mode generation; the third is based on a program control mode, namely, a step signal is generated through the DA of the control chip, and then a high-frequency signal is filtered to obtain a triangular wave. No matter which implementation method is adopted, in order to obtain the triangular wave with high precision, closed-loop control needs to be carried out on the triangular wave generator, and then the parameter value of the output triangular wave needs to be obtained in real time. However, the existing acquisition of the triangular wave parameter value either adopts a complex hardware circuit or requires a complex software algorithm, and the complexity and cost of the triangular wave generator are increased.

Disclosure of Invention

The invention aims to provide a triangular wave signal parameter measuring circuit. The invention has the characteristics of simple hardware structure, low cost and strong anti-interference capability.

The technical scheme of the invention is as follows: a triangular wave signal parameter measurement circuit is characterized in that: comprising a voltage reference V_ref1And V_ref2A circuit, a comparison circuit and a capture circuit;

the voltage reference V_ref1And V_ref2Circuit for generating a voltage reference with high precision and high stability, and satisfying V_min＜V_ref2＜V_ref1＜V_max(ii) a Wherein: v_min、V_maxAre respectively triangular wave signals v_tri(t) minimum and maximum values;

the comparison circuit realizes the triangular wave signal v to be measured_tri(t) and V_ref1And V_ref2Comparing to obtain PWM signals

And

wherein: v. of_tri(t) is connected to the non-inverting input of the comparator 1, V_ref1Is connected with the inverting input end of the comparator 1; v. of_tri(t) is connected to the non-inverting input of the comparator 2, V_ref2Is connected with the inverting input end of the comparator 2; the output terminal of the comparator 1 is

The output terminal of the comparator 2 is

The capture circuit is to

And

the Capture ports of the Capture1 and the Capture2 which are respectively connected to the control chip respectively acquire

On-time of

On-time of

Rising edge and

time interval T between rising edges₂、

Falling edge and

time interval T between falling edges₅；

According to the obtained

T₂And T₅And V given above_ref1And V_ref2To give v_triMinimum value V of (t)_minMaximum value V_maxPeriod T, rise phase time T_upAnd a falling phase time T_down。

Compared with the prior art, the method has the following advantages:

the invention reduces the cost of the circuit through a simple hardware structure;

secondly, the system has relatively simple structure and low realization difficulty;

and thirdly, parameters are calculated by adopting a time capturing method, so that the precision is high and the anti-interference capability is strong.

Drawings

FIG. 1 is a schematic diagram of a triangular wave signal parameter measurement;

FIG. 2 is a schematic diagram of a circuit for measuring parameters of a triangular wave signal;

FIG. 3 is a flow chart of a time capture algorithm;

fig. 4 is a flowchart of the triangular wave parameter calculation.

Detailed Description

The invention is further illustrated by the following figures and examples, which are not to be construed as limiting the invention.

Examples are given. A triangular wave signal parameter measuring circuit mainly applies the geometric relationship of triangular waves, and the relationship is shown in figure 1. The variables are described as follows: v_ref1And V_ref2Respectively comparing voltage reference values; v_minAnd V_maxAre respectively triangular wave signals v_triMinimum and maximum values of (t), V_dcIs v is_triPeak to peak value of (t), i.e. V_dc＝V_max-V_min；T_upIs v is_tri(t) rise phase time; t is_downIs v is_tri(t) a fall phase time; t is v_tri(t) a period satisfying: t ═ T_up+T_down；

Is v is_tri(t) and a reference value V_ref1The logic relationship of the PWM signals obtained after comparison is as follows:

is v is_tri(t) and a reference value V_ref2The logic relationship of the PWM signals obtained after comparison is as follows:

is composed of

On-time of (d);

is composed of

On-time of (d); t is₂Is composed of

Rising edge and

the time interval between rising edges; t is₅Is composed of

Falling edge and

the time interval between falling edges. From the geometry of fig. 1, it can be seen that:

the simultaneous (2) and (3) can obtain:

obtaining T by the capturing unit₂And T₅On the basis of (a), calculating λ:

and obtained by the capture unit

On the basis of (A), and comprises:

combining (4), (5) and (6), and finishing to obtain T₃And T₄Comprises the following steps:

further, from (2), it is possible to obtain:

therefore:

due to the fact that

T₂、T₅Can be acquired by a capture unit, V_ref1、V_ref2Setting a reference value for the circuit, the value being known, so V_maxCan be calculated by equation (9).

And because:

because:

therefore:

because:

T_up+T_down＝T (12)

and because of the triangular wave v_tri(T) period T and

are identical and thus can be captured by

I.e. the period T may be obtained by the capturing unit. Therefore:

simultaneous (5) and (13) gives:

due to T, T₂、T₅Can be acquired by the capturing unit, so T can be calculated_up、T_down。

And because:

therefore, the simultaneous (14) and (16) can obtain:

the triangular wave v can be solved by the formula (17)_tri(t) peak-to-peak value V_dc。

Because:

V_dc＝V_max-V_min (18)

simultaneous (9), (18), solved to:

the triangular wave v can be obtained by solving (9), (17) and (19)_triMaximum value V of (t)_maxPeak to peak value V_dcAnd a minimum value V_minBy capture of

Can obtain a triangular wave v_triThe period T of (T), the triangular wave v can be obtained from (14) and (15)_tri(T) rise time T_upAnd a fall time T_downThe triangular wave v can be obtained by the above formula_tri(t) related parameters.

Triangular wave signal parameter measurementThe schematic diagram of the volume circuit is shown in FIG. 2, and mainly comprises a linear voltage regulator circuit and a voltage reference V_ref1And V_ref2Circuit, comparator circuit 1, comparator circuit 2 and MUC circuit. The linear voltage stabilizing circuit mainly realizes the input voltage V_inPerforming voltage stabilization treatment to obtain output voltage V meeting the requirement_o(ii) a Voltage reference V_ref1And V_ref2The circuit can be generated by a precision voltage chip and a precision voltage division circuit. The embodiment of the invention provides a method for realizing a reference V by adopting a commonly-used precise voltage stabilizing chip TL431_ref1And V_ref2Generation of (1); in the circuit, R1 is used for adjusting the current flowing through the TL431, so that the TL431 works in a reasonable working range and the precision of the TL431 is ensured; the R2, R3 and R4 form a precise voltage division circuit by using high-precision resistors to realize the reference V_refAnd V_ref2Generation of (1); the capacitors C1 and C2 play a role in resisting interference and stabilizing the reference voltage V_ref1And V_ref2(ii) a Non-inverting input terminal v of comparator 1_tri(t), the inverting input terminal V_ref1The output terminal is a signal

Non-inverting input terminal v of comparator 2_tri(t), the inverting input terminal V_ref2The output terminal is a signal

The MCU has two roles: the first and second Capture ports Capture1 and Capture2 are respectively connected

And

for obtaining

And

a time parameter of (d); II, obtaining

And

after the time parameter is obtained, the measuring algorithm provided by the invention is executed to obtain the triangular wave v_tri(t) related parameters.

FIG. 3 is a flow chart of a time capture algorithm, comprising:

(1) the initialization module is used for initializing the Capture1 and the Capture2 modules;

(2) starting a Capture1 and Capture2 module;

(3) is the Capture2 judged to have a rising edge? If yes, entering the step (4); otherwise, waiting;

(4) starting a timer and entering the step (5);

(5) is the Capture1 judged to have a rising edge? If yes, entering the step (6); otherwise, waiting;

(6) saving the current value of the timer to T₂Entering the step (7);

(7) is it judged whether a falling edge occurred in Capture 1? If yes, entering the step (8); otherwise, waiting;

(8) current value of timer minus T₂And the result is saved to

Entering the step (9);

(9) is it judged whether a falling edge occurred in Capture 2? If yes, entering the step (10); otherwise, waiting;

(10) current value of timer minus T₂And

saving the result to T₅Entering the step (11);

(11) is the Capture2 judged to have a rising edge? If yes, entering the step (12); otherwise, waiting;

(12) saving the current value of the timer to T, clearing the current value of the timer and stopping the timer, and entering the step (13);

(13) enabling the software to interrupt, and returning to the step (4);

fig. 4 is a flowchart of the triangular wave parameter calculation, including:

(1) entering a software interrupt program, and entering the step (2);

(2) get T, T₂、T₅、

And V_ref1、V_ref2Entering the step (3);

(3) computing

Entering the step (4);

(4) computing

Entering the step (5);

(5) computing

Entering the step (6);

(6) computing

Entering the step (7);

(7) exiting the software interrupt program;

the examples should not be construed as limiting the present invention and any modifications made based on the spirit of the present invention should be covered within the scope of protection of the present invention.

Claims (1)

1. A triangular wave signal parameter measurement circuit is characterized in that: comprising a voltage reference V_ref1And V_ref2A circuit, a comparison circuit and a capture circuit;

the voltage reference V_ref1And V_ref2Circuit for generating a voltage reference with high precision and high stability, and satisfying V_min＜V_ref2＜V_ref1＜V_max(ii) a Wherein: v_min、V_maxAre respectively triangular wavesSignal v_tri(t) minimum and maximum values;

the comparison circuit realizes the triangular wave signal v to be measured_tri(t) and V_ref1And V_ref2Comparing to obtain PWM signals

And

wherein: v. of_tri(t) is connected to the non-inverting input of the comparator 1, V_ref1Is connected with the inverting input end of the comparator 1; v. of_tri(t) is connected to the non-inverting input of the comparator 2, V_ref2Is connected with the inverting input end of the comparator 2; the output terminal of the comparator 1 is

The output terminal of the comparator 2 is

The capture circuit is to

And

the Capture ports of the Capture1 and the Capture2 which are respectively connected to the control chip respectively acquire

On-time of

On-time of

Rising edge and

time interval T between rising edges₂、

Falling edge and

time interval T between falling edges₅；

According to the obtained

T₂And T₅And V given above_ref1And V_ref2To give v_triMinimum value V of (t)_minMaximum value V_maxPeriod T, rise phase time T_upAnd a falling phase time T_down。

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