Electric power conversion systems – Current conversion – With auxiliary bucking or boosting emf
Patent
1994-04-11
1996-03-26
Wong, Peter S.
Electric power conversion systems
Current conversion
With auxiliary bucking or boosting emf
307 44, 307 82, H02M 753
Patent
active
055026346
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a regulated auxiliary power supply for use with personal computers and similar electronic equipment.
A personal computer includes a regulated power supply which produces the required supply voltage, normally 5 Volts, for the various loads within the computer. Such power supplies generally provide a 12 Volt output in addition. The power supply is regulated to maintain a constant voltage as the current requirements vary. A problem arises when it is desired to drive a remote terminal from the same power supply or to include circuitry in the computer that must be powered redundantly from two separate systems. If the supply is regulated according to the requirements of the main computer components, in the first case the voltage drop along the supply lead reduces the voltage at the auxiliary output, and in the second case the voltage at the auxiliary output is reduced by the series isolation diodes required to separate the two systems.
An object of the invention is to provide a regulated power supply capable of overcoming the aforementioned disadvantages.
According to the present invention there is provided in a system comprising a main load directly connected to a main regulated power supply and an auxiliary load connected to said main regulated power supply by a line in which a voltage drop occurs, said main regulated supply being connected at a near end of said line, and an auxiliary regulated power supply being connected at a far end of said line, said auxiliary regulated power supply comprising a pair of input terminals connected to said far end of said line and receiving an input voltage therefrom; a secondary voltage source; a pair of secondary terminals connected to said secondary voltage source; a pair of output terminals connected to said auxiliary load and supplying an output voltage; means for adding voltage from said secondary voltage source to said input voltage to provide said output voltage; means for applying said output voltage to said output terminals; and control means for sensing the voltage at said output terminals, said control means being operative to control said adding means in a feedback arrangement to maintain said output voltage at a constant level appropriate for said auxiliary load.
Preferably, the means for adding the voltage from the secondary source is a forward converter. At higher currents a push-pull converter may advantageously be employed.
By controlling voltage at the output terminals in this manner, a stable five volt with minimum current ripple can be readily maintained at the auxiliary output. Each ampere of current drawn from the main power supply generates one ampere of output current at the auxiliary output at the desired voltage, normally five volts.
The invention will now be described in more detail, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 shows a personal computer connected to a remote terminal running off a common power supply;
FIG. 2 shows an alternative arrangement where a circuit is powered redundantly from two separate systems;
FIG. 3 shows a known boost converter circuit;
FIG. 4 shows an arrangement in accordance with the invention for providing an auxiliary regulated power supply employing a forward converter; and
FIG. 5 shows an arrangement in accordance with the invention for providing an auxiliary regulated power supply employing a push-pull converter.
Referring now to FIG. 1, personal computer 1 comprises an internal regulated power supply 2, which drives a CPU 3 and other standard components (not shown). The computer 1 is connected to a remote terminal 4, which is driven by the same power supply 2 as the computer 1 over a lossy line 5, which causes a voltage drop across it.
A problem is that if the power supply is properly regulated for the CPU of the computer 1, the voltage drop across line 5 connecting the computer 1 to the terminal 4 causes the voltage applied to the remote terminal to become too low and consequently no longer regulated.
FIG. 2 shows an alternative situation where a
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Mitel Corporation
Riley Shawn
Wong Peter S.
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