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Adjustable Underfrequency Overfrequency Limiting Circuit

IP.com Disclosure Number: IPCOM000078154D
Original Publication Date: 1972-Nov-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 3 page(s) / 59K

Publishing Venue

IBM

Related People

Nunnery, WB: AUTHOR

Abstract

Referring to Fig. 1, there is shown a D/C to A/C voltage regulator having a frequency responsive ferroresonant transformer as the output voltage element. A D/C source 2 is applied to the input of an inverter 3. The inverter in effect chops up the D/C level at a frequency f , determined by the output of a voltage-controlled oscillator 29 coupling the inverter over a common path 31. The pulse train of magnitude V is applied to the over a common path 31. The pulse train of magnitude V is applied to input of 5 of the transformer 7. In Fig. 2, There is shown a typical inverted n-shaped characteristic of a ferroresonant transformer. It is desired to have the operating point of the transformer within the broad linear portion of that characteristic.

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Adjustable Underfrequency Overfrequency Limiting Circuit

Referring to Fig. 1, there is shown a D/C to A/C voltage regulator having a frequency responsive ferroresonant transformer as the output voltage element.

A D/C source 2 is applied to the input of an inverter 3. The inverter in effect chops up the D/C level at a frequency f , determined by the output of a voltage- controlled oscillator 29 coupling the inverter over a common path 31. The pulse train of magnitude V is applied to the over a common path 31. The pulse train of magnitude V is applied to input of 5 of the transformer 7. In Fig. 2, There is shown a typical inverted n-shaped characteristic of a ferroresonant transformer. It is desired to have the operating point of the transformer within the broad linear portion of that characteristic. It is observed that the output voltage V at 9 varies as the input frequency f in the linear region, by the relation V(0)9= k(1) f(S) + k(2) in the region f(L)< f(S)< f(H) where f(L) and f(H) are the low and high- frequency limits of the linear characteristic. Consequently, the output voltage can be increased or decreased by changing the pulse repetition frequency applied to its input, the supposition being that the ferroresonant transformer input is "tuned" to pass low-frequency components of which the pulse repetition frequency is the fundamental (lowest frequency component in the wave train).

It must be remembered that the D/C voltage source may have slowly or rapidly changing fluctuations. This is also true with the output load current I(L) . When viewed in the context of the inverted n-shaped characteristic, it has been observed that the characteristic may translate as a function of the line and load variations. The technical advance embodied in Fig. 1 is most specifically related to the use of limiting circuits in stabilizing a voltage regulator, having frequency dependent elements in its control loop, so that the regulator can maintain itself within a linear operating region. To accomplish this, the output voltage V(0) is sensed and applied as one input to a voltage amplifier 19. The output of the voltage amplifier is, in turn, applied to the voltage control oscillator 29 over a connecting path 21. The feedback path incorporates the necessary 180 Degrees phase shift through the action of the voltage amplifier 19. The gain of the voltage amplifier is varied as a function of the output of a voltage comparison amplifier 35, which comparison amplifier output drives the voltage amplifier gain control element. The voltage comparison amplifier output is formed from the difference between the output voltage change, as scaled down and applied to one input 33 of the comparison amplifier 35 and the magnitude of a reference voltage 37 applied as a second input. It will be observed that a resistive divider network is formed from the resistors R...