GB2259198A - An uninterruptable power supply - Google Patents
An uninterruptable power supply Download PDFInfo
- Publication number
- GB2259198A GB2259198A GB9118466A GB9118466A GB2259198A GB 2259198 A GB2259198 A GB 2259198A GB 9118466 A GB9118466 A GB 9118466A GB 9118466 A GB9118466 A GB 9118466A GB 2259198 A GB2259198 A GB 2259198A
- Authority
- GB
- United Kingdom
- Prior art keywords
- power supply
- supply device
- uninterruptable power
- amplifier
- converter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000012544 monitoring process Methods 0.000 claims description 7
- 230000000007 visual effect Effects 0.000 claims description 6
- 230000001629 suppression Effects 0.000 claims description 4
- 238000001914 filtration Methods 0.000 claims description 2
- 238000009499 grossing Methods 0.000 abstract description 4
- 238000001514 detection method Methods 0.000 abstract description 2
- 238000002955 isolation Methods 0.000 description 6
- 239000002253 acid Substances 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
- H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
- H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems
- H02J9/062—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems for AC powered loads
Landscapes
- Business, Economics & Management (AREA)
- Emergency Management (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Abstract
The supply has a wide input range DC-DC converter 8 energised from a rectified mains supply 6 and/or from a battery 16 when there is a mains input shortfall or failure. Converter 8 and a filter 20 produce a rectified sinewave ripple output of 300V DC peak at 100 Hz with slight smoothing in the troughs, this output being applied to an amplifier 12 which provides a sinewave A.C. output via a transformer 24. The amplifier 12 is preferably a linear, push-pull MOSFET amplifier which amplifies a reference signal provided by a master control 14. The reference signal is a rectified sinewave ripple output of 290V DC peak in phase with the supply from converter 8, so that the amplifier 12 works as if supplied by the 10V differential between its 300V power input and ifs 290v reference input. A monitor 10 turns off a battery charger 30 and turns on alarm indicators 22 on detection of a sag or failure in the mains supply. The monitor 10 measures the voltage of the trough of the rectified mains input to converter 8. <IMAGE>
Description
AN UNINTERRUPTABLE POWER SUPPLY DEVICE
This invention relates to an uninterruptable power supply device.
Uninterruptable power supply devices are known.
They usually employ relatively high output power amplifiers and relatively large heat sinks for dissipating heat generated by these amplifiers.
It is an aim of the present invention to provide an uninterruptable power supply device which allows a substantial de-rating of the output power amplifier, and a substantial reduction on the size of the heat sink required for the amplifier.
Accordingly, in one non-limiting embodiment of the invention, there is provided an uninterruptable power supply device comprising rectifier means for rectifying mains current, a DC to DC converter for receiving rectifying mains current from the rectifier means, monitor means for monitoring the rectified mains input to the DC to DC converter, an amplifier for amplifying the output from the DC to DC converter, and control means for causing current from at least one battery automatically to be provided for the DC to DC converter substantially immediately the monitoring means detects a mains input shortfall or failure.
Usually, the uninterruptable power supply device will be one in which the monitor means monitors the voltage of the trough of the rectified mains input.
Preferably, the amplifier is a linear amplifier.
However the amplifier may be any of class A, AB, B, C or D.
The uninterruptable power supply device may employ circuitry allowing the benefit of the low radio frequency interference generation of the linear amplifier to be used, without an attendant drop in efficiency of power usage usually associated with linear amplifiers.
Preferably, the linear amplifier is a linear mosfet amplifier. When the uninterruptable power supply employs a linear mosfet amplifier, then the uninterruptable power supply device may allow a substantial derating of the output power mosfet and a substantial reduction in the size of heat sinks attached to the output power mosfets on the linear amplifier.
The linear mosfet amplifier may have a 300V 100Hz ripple supply and may amplify a 290V 100Hz ripple signal in phase with this supply, and may work from a differential of approximately lOV that exists between supply and signal throughout their ripple waveforms.
The uninterruptable power supply device is such that, by careful siting of heat sinks, forced cooling by a fan on small sizes of uninterruptable power supply devices up to typically 1.0/1.5 KVA is not necessary. This removes the power drain otherwise needed to drive the fan, thereby still further improving the overall efficiency of the uninterruptable power supply device.
The uninterruptable power supply device of the present invention is able to operate in an extremely silent manner. Minimal heat, noise and radio frequency interference generation are all key requirements in modern working environments, for example in offices, where the uninterruptable power supply devices are needed to operate, for example in supplying continuous power to computers.
Usually, the uninterruptable power supply device will be manufactured and sold with the said at least one battery. If desired however, the uninterruptable power supply device may be manufactured and sold without the said at least one battery, in which case, the end user will provide the battery or batteries.
The uninterruptable power supply device may include external visual alarms and indicators. The alarms and indicators may be light emitting diode alarms and indicators.
The uninterruptable power supply device may include at least one ON/OFF switch.
The uninterruptable power supply device may include a filter for spike suppression.
The DC to DC converter may include a filter network for filtering out radio frequency interference.
The uninterruptable power supply device may be started without mains input provided the battery or batteries are charged.
An embodiment of the invention will now be described solely by way of example and with reference to the accompanying drawings in which:
Figure 1 shows the front of a typical uninterruptable power supply device;
Figure 2 shows the rear of the uninterruptable power supply device shown in Figure 1; and
Figure 3 is a block circuit diagram for the uninterruptable power supply device shown in Figure 1.
Referring to the drawings, there is shown an uninterruptable power supply device 2 which comprises the circuit shown in Figure 3 housed in a cabinet 4 as shown in Figures 1 and 2.
Referring especially to Figure 3, the device 2 comprises rectifier means 6 for rectifying mains current, a wide input range DC to DC converter 8 for receiving rectified mains current from the rectifier means 6, and monitor means 10 for monitoring the voltage of the trough of the rectified mains input to the DC to DC converter.
The device 2 further comprises a linear mosfet amplifier 12 and associated circuitry. Control means in the form of a motherboard master control 14 causes current from a 24V/48V/96V battery pack 16 automatically to be provided for the DC to DC converter 8 substantially immediately the monitoring means 10 detects a mains input shortfall or failure.
The device 2 includes an input filter 18 for suppressing mains input spikes which would otherwise reach the mains rectifier 6.
A filter network 20 is provided for suppressing any radio frequency interference generated by the DC to DC converter 8. Audio and visual alarms 22 are arranged to operate consequent upon a detected mains input shortfall or failure.
The device 2 further includes an isolation transformer 24 and a computer interface 26 as shown.
The device 2 operates as follows. Mains input via line 28 passes to the input filter 18 for spike suppression. The mains input is then rectified by the rectifier means 6 to 340V DC peak.
The rectified current then passes into the DC to
DC converter 8 which is a wide input range DC to DC converter. The DC to DC converter 8 generates a rectified sine wave ripple output of approximately 300V DC peak at 100Hz with slight smoothing in the troughs. The filter network 20 is formed as an integral part of the DC to DC converter 8 and it filters out the radio frequency interference.
The same output from the DC to DC converter 8 is generated from the 24V DC/48V DC/96V DC input supplied to it from batteries in the battery pack 16. This battery voltage is always present without any switching between this and the mains input at the input side of the DC to
DC converter 8. By using the monitor means 10 continuously to measure the voltage of the trough of the rectified means input to the DC to DC converter 8, the minimum of which is 50V when mains input Vrms drops below 15% of nominal, any sag or failure in the voltage of the mains input to the device 2 is detected.When mains input Vrms drops below 15% of nominal, some power from the batteries is taken on all 50V troughs to make up the mains input shortfall or failure, without any break or discontinuity in supply to the DC to DC converter 8 and the rest of the device 2 to the point where the mains input Vrms drops below approximately 20% of nominal when essentially all input power to the DC to DC converter 8 is taken from the batteries.
The 300V DC peak/lOOHz rectified sine wave ripple output from the filter network 20 is then fed into the linear mosfet amplifier 12. Phased with this 300V DC peak supply is a 290V DC peak supply signal of similar rectified sine wave ripple waveform generated independently by the motherboard master control 14. Thus the linearmosfet amplifier 12 works. as if supplied by the lOV approximate differential that exists between the two waveforms throughout the rectified sine wave ripple waveform cycle, as explained more fully below.
Special protection circuitry controls the mosfets in the linear amplifier 12 within their safe operating area at all times.
The resulting sine wave output from the amplifier 12 is fed into the isolating transformer 24, which can either be of toroidal or laminated construction.
Overwinds on this isolation transformer 24 generate the voltage supply for both the motherboard master control 14 and a battery charger 30. Thus the battery charger 30 is fed with clean power for better operation. When mains power fails, the battery charger 30 is switched off.
The mains output from the device 2 is fed from the isolation transformer 24 into the power output socket 32 (see Figure 2) or to a hard wired terminal.
The output from the device 2 can be set at any voltage AC or at any frequency depending upon the required operation of the device 2, by simple adjustment of potentiometers for both frequency and voltage.
The input filter 18 and the mains rectifier 6 are preferably such that the input filter 18 effects spike suppression and slight smoothing, with a low value smoothing capacitor to generate 340V peak 100Hz ripple output with the low point on the ripple trough being approximately 50V. This part of the circuit also preferably contains a small value thermistor for inrush current protection.
The DC to DC converter 8 generates the 300V DC peak 100Hz ripple output with the minimum ripple trough voltage being approximately 20V.
The filter network 20 is preferably a low-path filter, typically less than 400Hz, to filter out both radiated and conducted radio frequency interference. The filter network 20 also preferably includes a reservoir capacitor to smooth the bottom part of the ripple by increasing its minimum point, approximately 20V to approximately 30V.
The linear mosfet amplifier 12 is preferably a Class "B" push-pull amplifier running at 50Hz, 60Hz, 400Hz or any other required output frequency. Each mosfet in the amplifier 12 has its own protection circuit to ensure safe operating area ratings are not exceeded under any circumstances. As mentioned above, because the waveform generated by the motherboard master control 14 is used as an independent generated reference signal into the mosfets of the amplifier 12, and the 300V 100Hz supply to the amplifier 12 from the DC to DC converter 8 is in phase with this 290V 100Hz signal voltage, with the motherboard master control 14 being the common source for both waveforms, the amplifier 12 works with the differential voltage that exists between the two waveforms, this being approximately 10 volts throughout their cycle.Therefore the mosfets in the amplifier 12 can be de-rated by a factor of 2-4 times as the required dissipation is very considerably reduced.
The isolation transformer 24 preferably has an earth screen between primary and secondary, which effectively shorts out high voltage spikes emanating from mains anomalies on the mains input or interference being fed back into the device 2 from the output. The isolation transformer 24 has three secondaries, the first being at 240V AC output (or equivalent depending upon what VAC is required on the output),the second. being 54V AC (or equivalent) for the battery charger 30, and the third being lOV AC for output voltage regulation.
The battery charger 30 has constant current taper charge and constant voltage circuits to give the best type of charger characteristics for the batteries used, these usually being lead acid batteries.
The motherboard master control 14 comprises the following parts.
1. DC to DC power supply; generates +/- 15V DC +
12V DC and +/- 5V DC at approximately 40 watts.
2. Sine wave reference signal generator to give an
output sine waveform with minimum distortion;
phase locked to input mains.
3. Drive transformer fed from sine wave reference
signal generator rated at 290V/lOOHz for
rectified sine wave ripple reference signal for
the linear mosfet amplifier 12.
4. Pulse width modulator for the wide input range
DC to DC converter 8, phase locked looped to
input mains.
5. (a) minimum output power limit to sustain very
high inrush switch-on currents on start-up of
loads with the device 2 switched on.
(b) soft start capability to reduce inrush
currents on start-up from a re-set position.
6. Low battery voltage shut-off.
7. Output short-circuit protection.
8. Mains input voltage detection for battery
charger on/off.
9. The battery charger 30 with controlled charge
rate for optimum battery life.
10. A complete phase-lock loop system to interface
with other functions.
11. Mains change-over point at rated Vrms less 15%
for full on-line no-break continuous supply of
rated Vrms +/- 1% at device output.
12. Generation of signals for monitoring software.
The device 2 may advantageously provide the following features.
A. Very high efficiency using a linear amplifier.
B. Zero radiated and conducted radio frequency
interference on the input and output.
C. Very high load start-up capability with a current
crest factor of typically 4:1, giving compatability
between the uninterruptable power supply device 2
and its load during both start-up and running
conditions.
D. Full compatability with IEC-555.
E. True on-line performance meaning that there is
no break in the output whether that output is
supplied from the incoming mains or the self
contained batteries by way of motherboard master
control 14 and mains monitoring means 10.
F. Isolation between the input and the output.
G. Full sine wave output from the device with
minimal distortion.
H. Regulation of both input voltage and frequency
aberrations.
Generally, the uninterruptable power supply devices of the present invention may have a power output of up to lOKVA typically. Each uninterruptable power supply device is self-contained in a cabinet as shown in Figures 1 and 2 or, alternatively in a box or rack. Usually, the batteries are contained in the cabinet, box or rack, and these batteries are typically sealed lead acid batteries.
Where autonomy time on batteries is to be increased, additional batteries contained in an external enclosure or battery extension module (not shown) may be connected to the uninterruptable power supply device.
The audio and visual alarms 22 are typically external visual light emitting diode alarms and indicators.
The device 2 also has output on/off switches, together with a manual reset button to re-start the device 2 manually after a full battery discharge before input mains is restored, or shut down following prolonged short circuit or an overload etc. The external power output sockets 32 are provided such that the load to be protected by the device 2 can be plugged into these power output sockets 32 or can alternatively be hard-wired.
As shown in Figure 2, the device 2 has a battery fuse 34 and an external finned heat sink 36.
As shown in Figure 1, the audio and visual alarms 22 are provided in a control and alarm console 38.
The uninterruptable power supply device 2 may contain computer interface sockets for remote monitoring and/or interrogation and/or control of the uninterruptable power supply device.
It is to be appreciated that the embodiment of the invention described above with reference to the accompanying drawings has been given by way of example only and that modifications may be effected.
Claims (12)
1. An uninterruptable power supply device comprising rectifier means for rectifying mains current, a DC to DC converter for receiving rectified mains current from the rectifier means, monitor means for monitoring the rectified mains input to the DC to DC converter, an amplifier for amplifying the output from the DC to DC converter, and control means for causing current from at least one battery automatically to be provided for the DC to DC converter substantially immediately the monitor means detects a mains input shortfall or failure.
2. An uninterruptable power supply device according to claim 1 in which the monitor means monitors the trough of the rectified mains input.
3. An uninterruptable power supply device according to claim 1 or claim 2 in which the amplifier is a linear amplifier.
4. An uninterruptable power supply device according to claim 3 in which the linear amplifier is a linear mosfet amplifier.
5. An uninterruptable power supply device according to claim 4 in which the linear mosfet amplifier has a 300V 100Hz ripple supply and amplifies a 290V 100Hz ripple signal in phase with this supply, and works from a differential of approximately lOV that exists between supply and signal throughout their ripple waveforms.
6. An uninterruptable power supply device according to any one of the preceding claims and including the said at least one battery.
7. An uninterruptable power supply device according to any one of the preceding claims and including external visual alarms and indicators.
8. An uninterruptable power supply device according to claim 7 in which the alarms and indicators are light emitting diode alarms and indicators.
9. An uninterruptable power supply device according to any one of the preceding claims and including at least one ON/OFF switch.
10. An uninterruptable power supply device according to any one of the preceding claims and including a filter for spike suppression.
11. An uninterruptable power supply device according to any one of the preceding claims in which the DC to DC converter has a filter network for filtering out radio frequency interference.
12. An uninterruptable power supply device substantially as herein described with reference to the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9118466A GB2259198A (en) | 1991-08-29 | 1991-08-29 | An uninterruptable power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9118466A GB2259198A (en) | 1991-08-29 | 1991-08-29 | An uninterruptable power supply |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9118466D0 GB9118466D0 (en) | 1991-10-16 |
| GB2259198A true GB2259198A (en) | 1993-03-03 |
Family
ID=10700598
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9118466A Withdrawn GB2259198A (en) | 1991-08-29 | 1991-08-29 | An uninterruptable power supply |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2259198A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2318000A (en) * | 1996-09-13 | 1998-04-08 | Graham Chapman | Uninterruptible power supply |
| GB2322020A (en) * | 1997-02-05 | 1998-08-12 | Gregory Frank Smith | Emergency lighting |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1984003805A1 (en) * | 1983-03-14 | 1984-09-27 | Hindrik Stoet | Ac voltage stabilizer easily convertible into uninterruptible power supply (ups) |
| GB2137833A (en) * | 1983-04-08 | 1984-10-10 | Toshiba Kk | Uninterruptible power supply |
| EP0169756A1 (en) * | 1984-06-20 | 1986-01-29 | MOTEURS LEROY-SOMER (Société Anonyme française) | Stabilized electrical-power supply |
| WO1989001719A1 (en) * | 1987-08-21 | 1989-02-23 | Electronic Research Group, Inc. | Integrated uninterruptible power supply for personal computers |
| US4827151A (en) * | 1987-02-20 | 1989-05-02 | Kabushiki Kaisha Toshiba | Uninterruptible power supply utilizing a synchronized chopper for power factor improvement |
| US4876460A (en) * | 1989-03-27 | 1989-10-24 | Intellipower, Inc. | Uninterrupted power supply |
-
1991
- 1991-08-29 GB GB9118466A patent/GB2259198A/en not_active Withdrawn
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1984003805A1 (en) * | 1983-03-14 | 1984-09-27 | Hindrik Stoet | Ac voltage stabilizer easily convertible into uninterruptible power supply (ups) |
| GB2137833A (en) * | 1983-04-08 | 1984-10-10 | Toshiba Kk | Uninterruptible power supply |
| EP0169756A1 (en) * | 1984-06-20 | 1986-01-29 | MOTEURS LEROY-SOMER (Société Anonyme française) | Stabilized electrical-power supply |
| US4827151A (en) * | 1987-02-20 | 1989-05-02 | Kabushiki Kaisha Toshiba | Uninterruptible power supply utilizing a synchronized chopper for power factor improvement |
| WO1989001719A1 (en) * | 1987-08-21 | 1989-02-23 | Electronic Research Group, Inc. | Integrated uninterruptible power supply for personal computers |
| US4876460A (en) * | 1989-03-27 | 1989-10-24 | Intellipower, Inc. | Uninterrupted power supply |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2318000A (en) * | 1996-09-13 | 1998-04-08 | Graham Chapman | Uninterruptible power supply |
| GB2322020A (en) * | 1997-02-05 | 1998-08-12 | Gregory Frank Smith | Emergency lighting |
| GB2322020B (en) * | 1997-02-05 | 2001-04-04 | Gregory Frank Smith | Emergency lighting |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9118466D0 (en) | 1991-10-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |