SU1492303A1 - Measuring ac power converter - Google Patents

Abstract

This invention relates to electrical measuring technology. The purpose of the invention is to improve the accuracy of measuring AC power. The introduction of the null comparator 5 and the splitter 6 frequency provides switching of the switch 3 at times corresponding to the value of the instantaneous power close to zero. The frequency divider 6 ensures the equality of the half-cycles of conversion and the required switching frequency of the switch 3. The measuring converter of the AC power also contains input converters 1 and 2 of the current and voltage, respectively, and a multiplier 4. 1 Il.

Description

and

 with to

with

about

with

Inventing (vriuicHTc to electrical measuring equipment and M (it can be used in devices for measuring power and energy of alternating current).

The purpose of the invention is to improve the accuracy of measuring AC power.

The drawing shows a structural diagram of an AC power meter.

The ac power transducer includes an input current transducer 1 and an input voltage transducer 2, a switch 3, a multiplier 4,, a null comparator 5, and a frequency divider 6, the inputs of the current transducer 1 and voltage 2, and the outputs are connected to the first and second inputs of switch 3, respectively, the output of multiplier 4 is the output of the transmitter, and the first and second inputs are connected to the first and second outputs, respectively. m switch 3, the converter comprises in series a zero-comparator 5 and the frequency divider 6, a zero-input comparator 5 klux sub-ene to the output of the input voltage of the inverter 2 and output from the frequency divider 6 - vho- to the third row of the switch.

The measuring AC power converter operates as follows.

Input current transducers 1 and voltage 2 convert the current and voltage input signals into homogeneous, normalized signals proportional to them. The multiplier 4 multiplies the 3 output signals of the input current transducers 1 and the voltage supplied to its inputs through the switch 3. The switch 3 makes periodic switching of the inputs of the multiplier 4. In order to reduce the error due to the final switching time of the switch 3, the switching is performed at times corresponding to a value close to zero of the instantaneous power. The value of the instantaneous power is zero when the value of one of the input signals. Therefore, switch 3

Switch 3 is produced at times of zero crossing of the output signal of the input converter 2 voltage, fixed by the zero1-compressor 5. Connection of the zero comparator to the output of the input voltage converter 2 is due to the fact that the voltage varies within narrower limits than Current, and the accuracy of determining the moment of a signal crossing zero is significantly dependent on its amplitude.

With periodic signals at the inputs of the measuring converter, at the output of the null comparator 5, a sequence of rectangular pulses is generated, which follow the frequency of the input signals f, which is fed to frequency divider 6.

At the output of the frequency divider 6, a sequence of square-wave pulses is formed with a duty cycle equal to two and a frequency F f / nj where n is the division factor.

The output signal of the frequency divider 6 is fed to the third (control) input of the switch 3, which switches at the time of zero crossing voltage at the input of the device with frequency F. The frequency divider 6 ensures equal conversion half-periods and the required switching frequency of switch 3. I

The division factor n is selected taking into account the frequency of the input signals, the response time of the switch 3 and the required accuracy and speed of the converter. The informative parameter of the output signal of the AC power converter is its average value over the period of the output signal of frequency divider 6.

Since when switching switch 3 the value of the instantaneous power is close to zero, the distortion of the measurement information is minimal.

Claims (1)

Invention Formula An ac power transducer containing input current and voltage transducers whose inputs are the transducer inputs and the output terminals 4en respectively to the first and second inputs of the 5I 4 923О-j the torus, and forward, + ml |., a game and a second one, in succession, in series, the SERDIRON inputs of which are connected to the corresponding ilulcompltortor divider It depends on the first and second heights, the null-comportorl approach The switches are switched (5p, l output is connected to the output of the input converter by the output of the measuring transducer voltage, and the output of the divider, in that the frequency bodies to the third input of the terminal.