GB2540787A

GB2540787A - Universal switched mode power supply

Info

Publication number: GB2540787A
Application number: GB1513250.9A
Authority: GB
Inventors: Harding Moller Christopher
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-07-28
Filing date: 2015-07-28
Publication date: 2017-02-01
Also published as: GB201513250D0

Abstract

A switched mode power supply (SMPS) system with circuitry for high voltage inputs 1 and for low voltage inputs 2, and having regulatory means to provide the required power to a load 8 regardless of the electrical voltage supplied. A switch 3 is incorporated in the circuitry which disconnects the low voltage module to avoid damage from a high voltage input, when a high voltage is detected by a detection circuit 4. In a first embodiment, when a high voltage is supplied, the low voltage output is in a serial configuration with the high voltage output. In a second embodiment, the two regulators are connected in parallel configuration. There may be diodes to protect against reverse current flow. The output from the high voltage circuitry may be connected to the input for the low voltage circuitry.

Description

DESCRIPTION

Universal Switched Mode Power Supply

This invention relates to a system for converting any kind of electrical supply of sufficient power to supply a load that has specific voltage and current requirements. A switched-mode power supply (SMPS) typically comprises a bridge rectifier to ensure that the electricity supply is of the correct polarity, followed by circuitry to condition the electrical supply to suit the load to be supplied. This circuitry may be designed to convert a high voltage at low current into a lower voltage at a higher current, or vice-versa, or it may be designed to provide specific voltage/current characteristics to suit the load. Whilst the load is likely to have very specific requirements, the regulating effect of the circuitry means that the input voltage may vary over a wide range, typically with a max/min voltage ratio up to about 3:1.

In situations where there is great uncertainty about the voltage or nature of the electricity supply, it will be advantageous to have an SMPS that is truly universal, accepting inputs ranging from a few volts DC to 250VAC or more, and providing power to the load that meets the load’s requirements, regardless of the electricity supplied (provided of course that the electricity supply has sufficient power).

Developing switched mode regulator circuitry to operate over input voltage ranges of greater than 3:1 has proved challenging. Therefore, according to the present invention, and referring to Fig.l or Fig.2, an SMPS operates in two distinct modes, according to whether high or low voltage is supplied. It comprises two regulator modules, one designed for high voltage inputs (1), and one for low (2). In order that a high supplied voltage should not damage the low voltage module, a high-speed switch is incorporated (3) which disconnects the low voltage module when this occurs, as detected by a high voltage detection circuit (4). The high voltage circuit typically shuts down of its own accord, when a low voltage is applied, and so it does not need to be disconnected in low-voltage mode.

The load (8) needs to be supplied, regardless of whether the electricity supplied is of high or low voltage. This may be achieved in two ways. In a first embodiment shown in Fig.l, when high voltage is supplied, the low voltage output of the high voltage regulator module is fed into the input of the low voltage regulator (“serial configuration”).

In a second embodiment shown in Fig.2, the outputs of the two regulators are connected together (“parallel configuration”).

In either configuration, the regulator that is not providing the power in this mode may experience power coming into its output from the other regulator. If the circuitry of the regulator is such that this would cause a problem, an additional diode can be added (5) or (6).

The bridge rectifier (7) is present in both configurations, to ensure the correct polarity of the supply, regardless of whether AC or either polarity of DC is provided.

Claims

1. A switched mode power supply system comprising circuitry for high voltage inputs and circuitry for low voltage inputs, and an electronic switch to protect the low voltage circuitry from damage by high voltages.

2. A switched mode power supply as in 1, in which the outputs from the circuitry for the two operating modes are simply connected together, if necessary with one or two protection diodes against reverse current flow into the output

3. A switched mode power supply as in 1, in which the output from the high voltage circuitry is connected to the input for the low voltage circuitry, if necessary with a protection diode against reverse current flow into the output of the high voltage circuitry in low voltage mode.

4. A system essentially as described above.