Electricity: power supply or regulation systems – In shunt with source or load – Using a three or more terminal semiconductive device
Patent
1994-01-18
1996-10-08
Wong, Peter S.
Electricity: power supply or regulation systems
In shunt with source or load
Using a three or more terminal semiconductive device
323326, G05F 1613, G05F 316, G05F 1618
Patent
active
055634982
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to an apparatus for supplying regulated direct electrical current and a method of effecting regulation of a direct current output from a switch mode regulator.
The problem to which this invention is directed relates to the problem of losses normally occasioned when attempting to provide a direct current switch mode regulated power supply with low noise.
It is well known to use a switch mode power supply to provide a regulated output.
However, using a switch mode technique inherently provides a high noise content and it has been conventional, if lower noise characteristics are required, to have the output fed into the input of a linear regulator.
A linear regulator of current design is inherently inefficient and significant power will be conventionally lost through the linear regulator with conventional circuit layouts.
Unfortunately, such inefficiency means that more power must be provided by the switch mode regulator with resultant larger heat dissipation and sizes of components becomes more of a problem.
An object of this invention is to provide an apparatus incorporating both a switch mode regulator and a linear regulator which are coupled in such a way that these can be caused to work in a more efficient way than has hitherto been the case.
SUMMARY OF THE INVENTION
According to this invention there is provided an apparatus for supplying regulated direct electrical current including a switch mode regulator with an input adapted to receive a varying source of electrical power, the output of the switch mode regulator being directed into the input of a linear regulator, and the output of the linear regulator being available as a source of low noise output direct current electrical power, the apparatus being characterised in that the voltage between the input and the output of the linear regulator is directed into and connected to the switch mode regulator such that the said voltage will act as a reference voltage for the regulation of the output voltage of the switch mode regulator.
Preferably, the linear regulator includes a controlling servo-loop with an output which is controlled by an input comprising a voltage signal which is the difference in voltage between a selected portion of the voltage of the linear regulator output on the one hand and a selected fixed reference voltage on the other hand, and the switch mode regulator includes a controlling servo-loop the output of which is controlled by a voltage signal which is the difference in voltage between the voltage between the input and output signal of the linear regulator on the one hand and a selected fixed reference voltage on the other hand.
Preferably, the first mentioned servo-loop has a substantially higher gain than that of the second mentioned servo-loop.
The invention can also apply to a method of effecting regulation of a direct current output from a switch mode regulator the output of which is being directed through a linear regulator, the method including the steps of supplying a varying supply of electrical power to the input of the switch mode regulator, taking a resultant voltage across the input and output of the linear regulator and directing this into the switch mode regulator such that it will be used as a reference voltage for controlling the output voltage of the switch mode regulator.
For a better understanding, this invention will now be described with reference to a preferred embodiment which shall be described with the assistance of drawings in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic drawing shown in block outline the arrangement of the embodiment, the elements of which include a switch mode regulator, a linear regulator, and a servo-loop, and
FIG. 2 is a circuit schematic for a fixed voltage supply regulator incorporating the embodiment.
BRIEF DESCRIPTION OF PREFERRED EMBODIMENTS
Referring in the first instance to FIG. 1, there is an input provided by input conductors 1 and 2 to a switch mode regulator 3. The output of the switch mode regula
REFERENCES:
patent: 4459537 (1984-07-01), McWhorter
patent: 4618812 (1986-10-01), Kawakami
patent: 4812736 (1989-03-01), Albach et al.
patent: 5216351 (1993-06-01), Shimoda
BHC Consulting Pty Ltd.
Halcro Nominees Pty Ltd.
Vu Bao Q.
Wong Peter S.
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