DE3939818C1 - Electronic multiplier using TDM process - has potential dividing coupling element between pulse generator and chopper - Google Patents

Abstract

The electronic multiplier works according to the TDM method and is intended, in particular, for power measurements. It possesses a voltage input and a current input, as well as an electronic switch, e.g. a vibrator. The voltage input signal controls a pulse generator and its output signal, through the vibrator, modulates the current input signal. Between the pulse generator and the vibrator a potential-separating coupling element is installed. USE/ADVANTAGE - Smaller overall size and cost. Power measurement conversion. Expensive and fault-prone voltage converter at circuit input can be dispensed with.

Description

The invention relates to an electronic multiplier according to the generic term of claim 1.

Electronic multipliers are becoming a lot used as a power transmitter. Power transmitters have the task the two required to determine performance sizes current and voltage too multi plicate and into one of the performance pro reshaping proportional size. Furthermore should the output circuit from the two input circles are electrically isolated.

Power transmitters according to different Multiplication methods are known. So z. B. from H. Vonarburg an impulse wide-pulse-pause-pulse amplitudes -Multiplier for performance measurement (Landis & Gyr - Announcements 1969, Issue 8, pp. 14-24).

In the known power transmitters it is necessary to ensure the galvanic isolation both input sizes

• a) by transformers
• b) by other electronic switching circles (isolation amplifier) to ent from the circuit below couple.

Point b) is currently for cost reasons practically not applied at all. Furthermore isolation amplifiers are often too large. When separated by transformers a so-called Current transformers used, in voltage a so-called voltage converter. However, current transformers are almost with today arbitrary accuracy and also very small producible while the voltage converter the weak point is. The tension wall l must be tall (less stressed Transformer) is often only limited controllable (80-120% of the nominal voltage) and causes a phase shift between primary and secondary voltage. This in turn is done through RC links compensated, resulting in another disadvantage results. Conventional LMU only work within a narrow frequency range  with the defined accuracy.

These and other disadvantages have been overcome one could avoid directly over one ohmic voltage divider the input tap voltage. But that would work the required galvanic isolation ver loren. Remedy would be isolation amplifiers offer, but these are from the above often not a viable solution.

The object of the invention is therefore while maintaining the galvanic doors and to avoid the explained Disadvantages a space-saving and cost favorable principle to offer the tension input ohmic to the multiplier (or LMU) to be able to couple.

This task is characterized by the de Feature of claim 1 solved. Advantageous configurations of the Multi are plizierers according to claim 1 specified in the subclaims.

The new thing about the Multi presented here plicician is now that if one multiplier after the pulse ratio modulation principle used, these impulses already exist anyway are. You can then go into this pulse path at will optocouplers, pulse transform mators or other impulse-transmitting Interpose elements. Depending on the use The element must have the pulse output be reinforced or regenerated on the side. From there, the multiplier works like a conventional impulse ratio modulated multiplier.

The present multiplier be is made of 2 galvanically isolated Divide by two separate voltage sources must be supplied. The one output voltage modulates a pulse gene rator. The voltage can be above an ohm voltage divider immediately supplied leads. After the pulse generator a galvanically isolating component follows.

Depending on the element used comes between Impulse generator and this another Trei level. After the separation stage is the Impulse, again depending on the use  component, regenerated or reinforced. The pulse available here follows a chopper that controls the second input voltage corresponding to the Pulse train chopped up. This second one is electrically isolated by a Current transformers because, as mentioned above, do not create any significant problems. The electri emerging behind the chopper cal signal is filtered and amplified. The output signal is then the product of the two input signals.

The advantage is that the expenditure voltage with errors converters at the input of the circuit are omitted can and still a galvanic door voltage (two separate power supplies provided).

Claims (6)

1. Electronic multiplier according to the TDM method, in particular for power measurement, with a voltage input and a current input and an electronic switch, for. B. a chopper, the voltage input signal controls a pulse generator and its output signal modulates the current input signal via a chopper, marked net by a potential-separating coupling element between the pulse generator and chopper. 2. Electronic multiplier after Claim 1, thereby characterized in that as a coupling element an optocoupler is provided. 3. Electronic multiplier after Claim 1, thereby characterized in that as a coupling element a pulse transformer is provided is. 4. Electronic multiplier after Claim 1, thereby characterized in that as a coupling element other impulse-transmitting elements are provided. 5. Electronic multiplier after one of claims 1 to 4 thereby characterized that between pulse generator and coupling element a Zwi is provided. 6. Electronic multiplier after one of claims 1 to 5 thereby characterized that between coupling element and chopper an amplifier or a pulse regenerator see is.