RU214610U1 - ACTIVE POWER TO DC VOLTAGE CONVERTER - Google Patents

Abstract

The utility model relates to electrical measuring technology and can be used to measure active power in AC circuits. The converter contains an amplitude detector, a quadrature phase shifter, a comparator, a single vibrator, an integrator with a reset, a frequency-voltage converter, a reference voltage source, an adder, a controlled phase shifter and a multiplier. The input of a signal proportional to the voltage of the circuit under study is connected through a quadrature phase shifter to the input of a controlled phase shifter, the output of which is connected to the first input of the multiplier, the second input of which is connected to the output of an amplitude detector, the input of which is connected to the input of a signal proportional to the current of the circuit under study, and to the input of the comparator, the output of which is connected to the input of the one-shot and the input of the frequency-voltage converter, the output of which is connected to the input of the integrator with reset, the reset input of which is connected to the output of the one-shot, the output of the integrator with reset is connected to the first input of the adder, the second input of which is connected to the source of the setting signal, the output The adder is connected to the control input of the controlled phase shifter, and the output of the controlled phase shifter is the output of the device. The technical result of the claimed utility model is to increase the speed of the converter. 2 ill.

Description

The utility model relates to electrical measuring technology and can be used to measure active power in AC circuits.

Known active power meter [USSR Author's certificate No. 951167, IPC G01R 21/06, publ. 08/15/1982], containing a voltage converter, a current converter, a measuring signal converter, a recorder, a measuring converter including a field-effect transistor, an analog adder, a corrector, a voltage divider, a voltage-to-current converter, a low-frequency filter.

This device has low speed due to the presence of a low-frequency filter and low accuracy due to the non-linearity of the characteristics of the field-effect transistor.

The closest analogue to the proposed utility model is a converter of active power to DC voltage [USSR Author's certificate No. 1076840, IPC G01R 21/00, publ. February 28, 1984], containing a control unit, an integrator, a switch, a reference voltage source, an adder, a low-pass filter and a comparator, the switch inputs being connected to the input buses of the converter and the outputs of the reference voltage source, the control inputs to the outputs of the control unit, and the first output - to the input of the integrator, the first input of the comparator through the adder is connected to the outputs of the switch, the output - to the input of the control unit, and the second input - to the output of the integrator and through a low-pass filter - to the output bus of the converter.

This technical solution was chosen as a prototype.

The disadvantage of this converter is the low speed due to the large time constant of the low-pass filter. The time constant of the low-pass filter is chosen sufficiently large based on the provision of specified voltage ripples at the lowest frequency of the operating range, which predetermines the low speed of the converter over the entire operating frequency range.

The technical result of the claimed utility model is to increase the speed of the converter.

The specified technical result is achieved by the fact that in the known active power to DC voltage converter containing a reference voltage source, an integrator, a comparator and an adder, an amplitude detector, a quadrature phase shifter, a single vibrator, a controlled phase shifter, a frequency-voltage converter and a multiplier are additionally introduced, and the integrator performed with a reset, and the input of the signal proportional to the voltage of the circuit under study, through a quadrature phase shifter, is connected to the input of the controlled phase shifter, the output of which is connected to the first input of the multiplier, the second input of which is connected to the output of the amplitude detector, the input of which is connected to the input of the signal proportional to the current of the circuit under study , and the input of the comparator, the output of which is connected to the input of the one-shot and the input of the frequency-voltage converter, the output of which is connected to the input of the integrator with reset, the reset input of which is connected to the output of the one-shot, the output of the integrator with reset connected to the first input of the adder, the second input of which is connected to the source of the setting signal, the output of the adder is connected to the control input of the controlled phase shifter, and the output of the controlled phase shifter is the output of the device.

The essential differences of the proposed converter are the introduction of an amplitude detector, a quadrature phase shifter, a single vibrator, a controlled phase shifter, a frequency-voltage converter, a multiplier, an integrator with a reset, as well as the organization of new connections between the device elements. The combination of elements and connections between them provide a positive effect - an increase in the performance of the converter.

The essence of the utility model is illustrated by drawings. In FIG. 1 shows a functional diagram of the active power converter, Fig. 2 - time diagrams of voltages u _u , u _i , u ₁ -u ₃ , u ₅ , u ₇ and u ₈ .

The converter (Fig. 1) contains an amplitude detector 1, a quadrature phase shifter 2, a comparator 3, a single vibrator 4, an integrator with a reset 5, a frequency-voltage converter 6, a reference voltage source 7, an adder 8, a controlled phase shifter 9 and a multiplier 10.

The meter works as follows.

The signal u _u \u003d U _mu sinωt, proportional to the voltage of the circuit under study, is fed to the input of the quadrature phase shifter 2, and at its output a voltage u ₁ is formed, phase-shifted by 90 ° relative to u _u in the lagging side (Fig. 2):

u ₁ \u003d U _mu sin (ωt-90 °),

where ω=2πf is the circular frequency of the mains voltage.

In this case, the signal u _i \u003d U _mi sin (ωt-ϕ) (where ϕ is the phase angle between the voltage and current of the circuit under study), proportional to the current of the circuit under study, is fed to the input of the comparator 3, which converts this voltage into a voltage u _{2 of} a rectangular shape (Fig. 2), which is fed to the inputs of the frequency-voltage converter 6 and single vibrator 4.

On the fronts of the voltage pulses u ₂ , a single vibrator 4 is launched and narrow pulses u _{3 of} a fixed duration with a frequency ω are formed at its output, which are fed to the reset input of the integrator with reset 5. At the same time, the frequency-voltage converter 6 converts the frequency of these pulses into a DC voltage U ₄ positive polarity value:

where K _PCHN - the transfer coefficient of the converter frequency-voltage 6;

ƒ - voltage frequency of the circuit under study;

ƒ _max - maximum operating frequency of the converter;

In this case, the value of K _PSN is selected from the condition for obtaining the maximum output voltage U ₄ =10 V at ƒ _max , i.e. K _PCHN \u003d 10 / ƒ _max .

The output voltage U ₄ of the frequency-voltage converter 6 is fed to the input of the integrator with reset 5.

At the output of the integrator with reset 5, a sawtooth voltage u _{5 of} negative polarity is formed with a frequency ƒ of the voltage of the converter circuit under study, the amplitude of which is determined by the formula:

where U _5m - the amplitude of the output voltage of the integrator with reset 5;

T - voltage period of the investigated circuit u _u ;

f - voltage frequency of the investigated circuit u _u ;

R is the resistance of the integrator resistor with reset 5;

C - integrator capacitor capacitance with reset 5.

Thus, when choosing the integration constant RC of the integrator with reset 5 equal to RC=1/ƒ _max , the amplitude of its output voltage U _5m does not depend on the voltage frequency u _u in the entire operating frequency range of the converter.

The output voltage u _{5 of} the integrator with reset 5 is added in the adder 8 with the bias voltage u ₆ \u003d U _cm \u003d 5 V from the reference voltage source 7, as a result of which an alternating sawtooth voltage u ₇ with an amplitude of 5 V is formed at the output of the adder 8. This voltage is applied to control input of controlled phase shifter 9.

The device uses a controlled phase shifter 9, which allows you to linearly change the phase ψ of the input signal from -180° to +180° when the control voltage changes from -5 V to +5 V (Fig. 2). This sawtooth control voltage u ₇ acting on the controlled phase shifter 9 changes the phase ψ of its input signal from -180° to +180° with frequency ω voltage u _u (Fig. 2).

Given that the voltage u _i of the circuit under study is in phase with the output voltage u _{5 of} the integrator with reset 5, a voltage u ₈ is formed at the output of the controlled phase shifter 9:

u ₈ =U _mu sin(ωt+ψ)=U _mu sin{ωt-90°+[180°-(ωt-ϕ)]}=U _mu sin(90°+ϕ)=U _mu cosϕ.

At the same time, the signal u _i =U _mi sin(ωt-ϕ), proportional to the current of the circuit under study, is fed to the input of the amplitude detector 1, at the output of which a voltage u ₉ =U _mi is formed.

The voltages u ₈ and u ₉ are multiplied in the multiplier 10, at the output of which and at the output of the converter, the output voltage u _out is formed:

where U, I are the effective values of the voltage and current of the circuit under study;

S is the total power of the circuit under study;

P is the active power of the circuit under study;

K _U - transmission coefficient of the voltage sensor;

K _I - current sensor transfer coefficient;

K _p is the transfer coefficient of the converter.

As a result, a constant voltage u _out is formed at the output of the converter, which is proportional to the active power of the circuit under study.

Thus, the use of an amplitude detector 1, a quadrature phase shifter 2, a single vibrator 4, a controlled phase shifter 9, a frequency-voltage converter 6, a multiplier 10 in the converter and the implementation of the integrator 5 with a reset allows achieving the required technical result - increasing the speed of the converter.

With the practical implementation of the proposed meter, the amplitude detector 1 can be performed according to one of the known schemes (A.J. Peyton, V. Volsh. Analog electronics on operational amplifiers. - M .: BINOM, 1994, p. 292, Fig. 11.17; p. 304, Fig. 11.29). The quadrature phase shifter 2 can be made according to the scheme (RF Patent No. 127554, H03V 27/00. Quadrature signal shaper, publ. 27.04.2013). Comparator 3 can be performed on the K554CA3 chip. Single vibrator 4 can be performed on the K561AG1 chip. An integrator with reset 5 can be performed on an operational amplifier (op-amp) according to the scheme (V.G. Gusev, Yu.M. Gusev. Electronics and microprocessor technology. - M .: Higher school, 2005. - p. 459, fig. 6.18, c). As a frequency-voltage converter 6, you can use a converter on the KR1108PP1 chip. The reference voltage source 7 is a conventional stable voltage source. Adder 8 is a non-inverting adder on the op-amp. The controlled phase shifter 9 can be made according to the scheme (Patent for PM No. 206198 of the Russian Federation, G01R 19/22. Controlled phase shifter, publ. 08/30/2021). The multiplier 10 can be performed on the KR525PS3 chip.

Claims (1)

Active power to DC voltage converter, containing a reference voltage source, an integrator, a comparator and an adder, characterized in that it additionally includes an amplitude detector, a quadrature phase shifter, a single vibrator, a controlled phase shifter, a frequency-voltage converter and a multiplier, and the integrator is made with a reset , moreover, the input of the signal proportional to the voltage of the circuit under study is connected through a quadrature phase shifter to the input of the controlled phase shifter, the output of which is connected to the first input of the multiplier, the second input of which is connected to the output of the amplitude detector, the input of which is connected to the input of the signal proportional to the current of the circuit under study, and the input comparator, the output of which is connected to the input of the one-shot and the input of the frequency-voltage converter, the output of which is connected to the input of the integrator with reset, the reset input of which is connected to the output of the one-shot, the output of the integrator with reset is connected to the first input of the sum mator, the second input of which is connected to the source of the driving signal, the output of the adder is connected to the control input of the controlled phase shifter, and the output of the controlled phase shifter is the output of the device.

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