CA2042589A1 - Process and device for adjusting and controlling a.c. voltages from the public mains - Google Patents
Process and device for adjusting and controlling a.c. voltages from the public mainsInfo
- Publication number
- CA2042589A1 CA2042589A1 CA 2042589 CA2042589A CA2042589A1 CA 2042589 A1 CA2042589 A1 CA 2042589A1 CA 2042589 CA2042589 CA 2042589 CA 2042589 A CA2042589 A CA 2042589A CA 2042589 A1 CA2042589 A1 CA 2042589A1
- Authority
- CA
- Canada
- Prior art keywords
- voltage
- uin
- input
- circuit components
- pulse width
- 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.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
- H02M5/02—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc
- H02M5/04—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters
- H02M5/22—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M5/275—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M5/293—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Inverter Devices (AREA)
- Ac-Ac Conversion (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The process deals with the input voltage (Uin) by means of pulse width modulation followed by filtering so that it is possible to directly adjust an output voltage (Uout) lying within the envelope curve of the input a.c. voltage (Uin).
The device for implementing the process includes voltage circuit components connected between the input voltage (Uin) terminals. The output voltage (UOut) is detected between the a.c. voltage circuit components (4, 5) whereby these components are activatable alternately to modulate the pulse width.
The process deals with the input voltage (Uin) by means of pulse width modulation followed by filtering so that it is possible to directly adjust an output voltage (Uout) lying within the envelope curve of the input a.c. voltage (Uin).
The device for implementing the process includes voltage circuit components connected between the input voltage (Uin) terminals. The output voltage (UOut) is detected between the a.c. voltage circuit components (4, 5) whereby these components are activatable alternately to modulate the pulse width.
Description
Z~4Z~;89 BAC~GROVND OF THE INVENTION
~iQL~ o~_the Inventio~
The objects of the invention are a process and a device for electronically adjusting and controlling a.c.
voltages. The voltages considered correspond to those commonly encountered in public mains. The typical power supply frequency in Europe is 50 ~z. In the U.S.A. and in other countries, it is 60 Hz. Certain specialized power supplies operate at a frequency of 400 Hz. The invention is designed for adjusting and controlling power supply frequencies between zero and 10 kHz, depending on the implementation of the device. The estimated voltage in public mains lies at nominal values between zero and 500 veff .
Des~iptiQ~ Qf prior art The conventional method of a.c~ voltage adjustment for the user is by phase controI, by a current inverter, or by frequency bundling, the first being the most widely used method. With a phase control of the voltage, part of the phase is cut off. This results in discontinuities in the voltage profile which can induce many upper harmonics.
These overlaid frequencies can be calculated by Fourier transform. The hookup of phase control devices in the network can result in negative feedback effects on the whole network and a decrease in the quality of the power supply. The sinusoidal a.c. voltage of the power supply network is to some extent distorted by overlaid high-frequency harmonics. Electrical companies commonly use superimposed control signals with frequencies between 100 Hz and 2 kHz. When too many upper harmonic in this frequency range are overlaid on the sinusoidal a.c. power signal by such devices, the control signals can no longer be detected reliably. In extreme cases, this leads to a , .. .
breakdown of the control functions in the network. The overlaid upper harmonics are usually extensively reduced by means o~ absorption circuits. These are costly resonant circuits composed of serial capacitors and inductances that are placed in line with the concerned device. The overlaid upper harmonics and discontinuities in the voltage profile also create disturbances in radio transmissions. These are eliminated by the use or noise filters.
A further side effect of phase control are power losses due to idle currents resulting from the phase angle between current and voltage. Such idle currents are an unnecessary load on the power supply network, and should therefore be held within strict limits. When certain limits are exceeded, costly idle current compensation systems with frequency cutoffs must be used. These generally consist of parallel capacitors and decoupling inductances by means of which the idle current is practically eliminated. The idle power consumption, however, is registered by appropriate meters and subsequently billed.
A second known method for controlling a.c. voltages is with a so-called Variac, optionally equipped with a servomotor. This is an electro-mechanical system, allowing only a slow adjustment. It is furthermore being slowly replaced because of its cos~ and size. It now finds use mainly in laboratory situations.
A further possibility for controlling a.c. voltages is the inverted rectifier or current inverter. It is a device that first transforms the a.c into a d.c. voltage by means of a rectifier/condensator circuit, and then generates an adjustable one- or three-phase a.c. voltage with variable frequency by means of an inverter. Such inverted rectifiers also present the problem that their rectifier/condensator circuit generates upper harmonics which must then be eliminated by means of absorption circuits. They also represent relatively high material costs.
Finally to be mentioned are electronic a.c. switches.
Several types of electronic switches are available, which basically allow the switching of an a.c. voltage by means of a Gratz rectifier circuit and a transistor. Such switches have, however, only been in use as replacements for relay-actuated switches.
The load on the public electrical power-supply networ~ has steadily increased over the past few years. It has, as a result, become increasingly urgent to tighten regulations concerning the allowable upper limits for upper harmonic disturbances, induced in particular by a.c. voltage control devices. Several countries have already established commissions to fix such thresholds. In Europe, the norm developed is the European Norm EN60555 1-3. Experts from various electrical companies have repeatedly expressed concern regarding the growing number of electronically controlled appliances with phase controlled voltage adjustment. Several relevant commissions nominated by the electrical power supply authorities are currently wor~ing on the legal definition of further, more stringent regulations.
SUM~ARY OF THE INVENTION
The objects of the invention are a process and device for electronically adjusting and controlling a.c. voltages from the public mains that solves the problems described above. The process according to the invention and the device for implementing it should in particular allow an adjusting and control of a.c. voltages that eliminates idle power losses and prevents the occurrence of upper harmonics.
2042~89 The proposed object is solved, according to this invention, by a process for adjusting and controlling a.c.
voltages from the public mains in which the input voltage is directly adjusted into an output voltage lying within the envelope curve of the input a.c. voltage by pulse width modulation followed by filtering.
The device and the process operate with minimal losses in that upper harmonics and idle power losses are prevented.
In specific applications, such as fluorescent lighting systems, a partial upper harmonic compensation can be effectuated through the modulation of the input wave form.
Besides its general use for the adjustment of a.c.
voltage, the voltage control system according to the invention can be used as d.c. voltage stabilizer or as three-phase voltage regulator. Particular applications are as regulators for lighting systems, motors, and starters. Its advantages for the user are manifold. They are, in particular, energy savings, for example through a hardly noticeable decrease of the light amplitude in a lighting system. The lifetime of the lighting tubes and starters is increased thanks to a lower operation voltage.
The need for absorption circuits for the suppression of upper harmonics is eliminated. And finally, smaller idle power compensators can be used, compared to phase-controlled devices where additional idle power compensation devices are needed.
A widespread use of the voltage control system according to the invention can lead to improved energy savings, optimization of the network loads, and the elimination of upper harmonic disturbances from the power supply.
2042~89 ~ F ~c~ IQ~Q~ DRAwINGs Reference is made to the diagrams for the further description of the voltage co~trol process and device according to the invention.
Figure 1 A schematic representation of the voltage control process and device according to the invention.
Figure 2 The internal structure of the a.c. voltage switch 2 in Fig. 1.
Figure 3 An alternative construction of an a.c. voltage switch with Gratz rectifier circuits.
DESC~IPTIQN OF PREFERRE~ EMBODIM~NTS
Fig. 1 shows the basic structure of the device according to the invention. The input voltage Uin is first filtered through the input filter 1, consisting here of two parallel capacitors C connected by an inductance L. A bi-directional switch 2 set between the input terminals follows the input filter 1. The device operates on the principle of a direct pulse width modulation of the a.c.
voltage by specially switched, fast a.c. voltage circuit components in the switch 2. The whole forms a power switch suitable for the adjustment of loads between zero and about 50 kW/kVA. The fast power switch 2 following the entrance filter 1 performs the pulse width modulation of the input voltage Uin. This modulated voltage is then transformed back into the sinusoidal, practically noise-free output voltage UOut by a further, output filter 3.
The value of the output voltage Uout can be adjusted to lie ; between zero and 100 % of the original input voltage Uin.
The heart of the device is the switch 2, which can process positive as well as negative input Uin voltages, i.e. a.c.
as well as d.c. voltages of any polarity.
An enlarged and more detailed view of the power switch 2 in Fig. 1 is given in Fig. 2. It comprises two a.c.
voltage circuit components 4, 5 , between which the output terminals (voltage Uout) are connected. These components 4, 5 are activatable alternately to modulate the pulse width. The a.c. voltage circuit components 4, 5 each consist of two antiserial power semiconductors T1, T2 and T3, T4, each in antiparallel with diodes D1, D2, and D3, D~. The operation of the circuit is illustrated with the example of the upper half 4 of the switch 2. With the first power semiconductor T1 switched on and a positive input voltage Uin, the current flows through this power semiconductor T1, while the parallel diode D1 experiences no current flow, and on through the diode D2 paralle to the power semiconductor T2, provided the voltage lies over the threshold of the diode D2. With a negative input voltage Uin, the functions of the power semiconductors T1, T2 are inverted. ~hen the power semiconductor Tl is switched off, there is no current flow for positive input voltages Uin, and the diode D2 is also idle. The power semiconductors take on opposite functions here as well, when the input voltage Uin is negative. The two identical circuits 4, 5 are activated alternately, with a small lag time. Their control is effectuated by means of the control voltages UCon and UCon~ between the power semiconductors T1, T2 and their counterparts T3, T4. They thus operate as a switch. The diodes D1-D4 can be part of the power semiconductors Tl-T4 (Power MOS Fet or IGBT) or discrete, external elements. The modulated a.c. voltage UmOd is shown schematically in Fig. 1. A proportional output voltage Uout with the same wave form and lying within the envelope of the input voltage Uin can be generated by an appropriate choice of the pulse~pause ratio. The output voltage Uout can be given any desired wave form by modulating the input over only half a period and by varying the pulse width. This application is desirable for the compensation of possible upper harmonics, i.e. for loads with a non-linear profile.
An alterna~ive implementation of the device is shown Fig.
3. The Gratz rectifier circuits Ds, D6 ensure that the voltages processed by the power semiconductors T5, T5 are always d.c. voltages, whether the input voltages are positive or negati.ve. The a.c. voltage circuit components 4, 5 therefore each comprise one Gratz rectifier circuits Ds, D6, whose a.c. inputs form the terminals of the a.c.
voltage circuit components 4, 5 and whose d.c. outputs are connected by a power semiconductor Ts, T6.
For the circuit in Fig.2 as well as the one in Fig. 3, the two a.c. voltage circuit components 4, 5 are most advantageously implemented as factory-assembled hybrid modules.
The invention allows the generation of a nearly ideal sinusoidal power signal through the pulse width modulation of the a.c. voltage. The process and device can be used for adjusting and controlling power supplies in the frequency range between zero and 10 kHz, while the voltage wave form can be adapted as desired by a variation of the pulse width and the pulse/pause ratio within the envelope of the input voltage Uin-
~iQL~ o~_the Inventio~
The objects of the invention are a process and a device for electronically adjusting and controlling a.c.
voltages. The voltages considered correspond to those commonly encountered in public mains. The typical power supply frequency in Europe is 50 ~z. In the U.S.A. and in other countries, it is 60 Hz. Certain specialized power supplies operate at a frequency of 400 Hz. The invention is designed for adjusting and controlling power supply frequencies between zero and 10 kHz, depending on the implementation of the device. The estimated voltage in public mains lies at nominal values between zero and 500 veff .
Des~iptiQ~ Qf prior art The conventional method of a.c~ voltage adjustment for the user is by phase controI, by a current inverter, or by frequency bundling, the first being the most widely used method. With a phase control of the voltage, part of the phase is cut off. This results in discontinuities in the voltage profile which can induce many upper harmonics.
These overlaid frequencies can be calculated by Fourier transform. The hookup of phase control devices in the network can result in negative feedback effects on the whole network and a decrease in the quality of the power supply. The sinusoidal a.c. voltage of the power supply network is to some extent distorted by overlaid high-frequency harmonics. Electrical companies commonly use superimposed control signals with frequencies between 100 Hz and 2 kHz. When too many upper harmonic in this frequency range are overlaid on the sinusoidal a.c. power signal by such devices, the control signals can no longer be detected reliably. In extreme cases, this leads to a , .. .
breakdown of the control functions in the network. The overlaid upper harmonics are usually extensively reduced by means o~ absorption circuits. These are costly resonant circuits composed of serial capacitors and inductances that are placed in line with the concerned device. The overlaid upper harmonics and discontinuities in the voltage profile also create disturbances in radio transmissions. These are eliminated by the use or noise filters.
A further side effect of phase control are power losses due to idle currents resulting from the phase angle between current and voltage. Such idle currents are an unnecessary load on the power supply network, and should therefore be held within strict limits. When certain limits are exceeded, costly idle current compensation systems with frequency cutoffs must be used. These generally consist of parallel capacitors and decoupling inductances by means of which the idle current is practically eliminated. The idle power consumption, however, is registered by appropriate meters and subsequently billed.
A second known method for controlling a.c. voltages is with a so-called Variac, optionally equipped with a servomotor. This is an electro-mechanical system, allowing only a slow adjustment. It is furthermore being slowly replaced because of its cos~ and size. It now finds use mainly in laboratory situations.
A further possibility for controlling a.c. voltages is the inverted rectifier or current inverter. It is a device that first transforms the a.c into a d.c. voltage by means of a rectifier/condensator circuit, and then generates an adjustable one- or three-phase a.c. voltage with variable frequency by means of an inverter. Such inverted rectifiers also present the problem that their rectifier/condensator circuit generates upper harmonics which must then be eliminated by means of absorption circuits. They also represent relatively high material costs.
Finally to be mentioned are electronic a.c. switches.
Several types of electronic switches are available, which basically allow the switching of an a.c. voltage by means of a Gratz rectifier circuit and a transistor. Such switches have, however, only been in use as replacements for relay-actuated switches.
The load on the public electrical power-supply networ~ has steadily increased over the past few years. It has, as a result, become increasingly urgent to tighten regulations concerning the allowable upper limits for upper harmonic disturbances, induced in particular by a.c. voltage control devices. Several countries have already established commissions to fix such thresholds. In Europe, the norm developed is the European Norm EN60555 1-3. Experts from various electrical companies have repeatedly expressed concern regarding the growing number of electronically controlled appliances with phase controlled voltage adjustment. Several relevant commissions nominated by the electrical power supply authorities are currently wor~ing on the legal definition of further, more stringent regulations.
SUM~ARY OF THE INVENTION
The objects of the invention are a process and device for electronically adjusting and controlling a.c. voltages from the public mains that solves the problems described above. The process according to the invention and the device for implementing it should in particular allow an adjusting and control of a.c. voltages that eliminates idle power losses and prevents the occurrence of upper harmonics.
2042~89 The proposed object is solved, according to this invention, by a process for adjusting and controlling a.c.
voltages from the public mains in which the input voltage is directly adjusted into an output voltage lying within the envelope curve of the input a.c. voltage by pulse width modulation followed by filtering.
The device and the process operate with minimal losses in that upper harmonics and idle power losses are prevented.
In specific applications, such as fluorescent lighting systems, a partial upper harmonic compensation can be effectuated through the modulation of the input wave form.
Besides its general use for the adjustment of a.c.
voltage, the voltage control system according to the invention can be used as d.c. voltage stabilizer or as three-phase voltage regulator. Particular applications are as regulators for lighting systems, motors, and starters. Its advantages for the user are manifold. They are, in particular, energy savings, for example through a hardly noticeable decrease of the light amplitude in a lighting system. The lifetime of the lighting tubes and starters is increased thanks to a lower operation voltage.
The need for absorption circuits for the suppression of upper harmonics is eliminated. And finally, smaller idle power compensators can be used, compared to phase-controlled devices where additional idle power compensation devices are needed.
A widespread use of the voltage control system according to the invention can lead to improved energy savings, optimization of the network loads, and the elimination of upper harmonic disturbances from the power supply.
2042~89 ~ F ~c~ IQ~Q~ DRAwINGs Reference is made to the diagrams for the further description of the voltage co~trol process and device according to the invention.
Figure 1 A schematic representation of the voltage control process and device according to the invention.
Figure 2 The internal structure of the a.c. voltage switch 2 in Fig. 1.
Figure 3 An alternative construction of an a.c. voltage switch with Gratz rectifier circuits.
DESC~IPTIQN OF PREFERRE~ EMBODIM~NTS
Fig. 1 shows the basic structure of the device according to the invention. The input voltage Uin is first filtered through the input filter 1, consisting here of two parallel capacitors C connected by an inductance L. A bi-directional switch 2 set between the input terminals follows the input filter 1. The device operates on the principle of a direct pulse width modulation of the a.c.
voltage by specially switched, fast a.c. voltage circuit components in the switch 2. The whole forms a power switch suitable for the adjustment of loads between zero and about 50 kW/kVA. The fast power switch 2 following the entrance filter 1 performs the pulse width modulation of the input voltage Uin. This modulated voltage is then transformed back into the sinusoidal, practically noise-free output voltage UOut by a further, output filter 3.
The value of the output voltage Uout can be adjusted to lie ; between zero and 100 % of the original input voltage Uin.
The heart of the device is the switch 2, which can process positive as well as negative input Uin voltages, i.e. a.c.
as well as d.c. voltages of any polarity.
An enlarged and more detailed view of the power switch 2 in Fig. 1 is given in Fig. 2. It comprises two a.c.
voltage circuit components 4, 5 , between which the output terminals (voltage Uout) are connected. These components 4, 5 are activatable alternately to modulate the pulse width. The a.c. voltage circuit components 4, 5 each consist of two antiserial power semiconductors T1, T2 and T3, T4, each in antiparallel with diodes D1, D2, and D3, D~. The operation of the circuit is illustrated with the example of the upper half 4 of the switch 2. With the first power semiconductor T1 switched on and a positive input voltage Uin, the current flows through this power semiconductor T1, while the parallel diode D1 experiences no current flow, and on through the diode D2 paralle to the power semiconductor T2, provided the voltage lies over the threshold of the diode D2. With a negative input voltage Uin, the functions of the power semiconductors T1, T2 are inverted. ~hen the power semiconductor Tl is switched off, there is no current flow for positive input voltages Uin, and the diode D2 is also idle. The power semiconductors take on opposite functions here as well, when the input voltage Uin is negative. The two identical circuits 4, 5 are activated alternately, with a small lag time. Their control is effectuated by means of the control voltages UCon and UCon~ between the power semiconductors T1, T2 and their counterparts T3, T4. They thus operate as a switch. The diodes D1-D4 can be part of the power semiconductors Tl-T4 (Power MOS Fet or IGBT) or discrete, external elements. The modulated a.c. voltage UmOd is shown schematically in Fig. 1. A proportional output voltage Uout with the same wave form and lying within the envelope of the input voltage Uin can be generated by an appropriate choice of the pulse~pause ratio. The output voltage Uout can be given any desired wave form by modulating the input over only half a period and by varying the pulse width. This application is desirable for the compensation of possible upper harmonics, i.e. for loads with a non-linear profile.
An alterna~ive implementation of the device is shown Fig.
3. The Gratz rectifier circuits Ds, D6 ensure that the voltages processed by the power semiconductors T5, T5 are always d.c. voltages, whether the input voltages are positive or negati.ve. The a.c. voltage circuit components 4, 5 therefore each comprise one Gratz rectifier circuits Ds, D6, whose a.c. inputs form the terminals of the a.c.
voltage circuit components 4, 5 and whose d.c. outputs are connected by a power semiconductor Ts, T6.
For the circuit in Fig.2 as well as the one in Fig. 3, the two a.c. voltage circuit components 4, 5 are most advantageously implemented as factory-assembled hybrid modules.
The invention allows the generation of a nearly ideal sinusoidal power signal through the pulse width modulation of the a.c. voltage. The process and device can be used for adjusting and controlling power supplies in the frequency range between zero and 10 kHz, while the voltage wave form can be adapted as desired by a variation of the pulse width and the pulse/pause ratio within the envelope of the input voltage Uin-
Claims (7)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Process for adjusting and controlling a.c. voltages from the public mains in which the input voltage (Uin) is directly adjusted into an output voltage (Uout) lying within the envelope curve of the input a.c.
voltage (Uin) by pulse width modulation followed by filtering.
voltage (Uin) by pulse width modulation followed by filtering.
2. Process according to claim 1, wherein the input voltage (Uin) is adjusted by a defined pulse/pause ratio, so as to generate a proportional output voltage with the same wave form.
3. Process according to claim 1, wherein the input voltage (Uin) is adjusted by a pulse width modulation over half a period so as to impart the desired wave form to the output voltage (Uout).
4. Device for implementing one of the aforementioned processes, wherein at least two a.c. voltage circuit components (4, 5), between which the output voltage (Uout) is taken, are connected between the input voltage (Uin) terminals, which circuits (4, 5) can be activated alternately for the purpose of pulse width modulation.
5. Device according to claim 4, wherein each of the a.c.
voltage circuit components (4, 5) consists of two antiserial power semiconductors (T1, T2; T3, T4), each in antiparallel with a diode (D1, D2; D3, D4).
voltage circuit components (4, 5) consists of two antiserial power semiconductors (T1, T2; T3, T4), each in antiparallel with a diode (D1, D2; D3, D4).
6. Device according to claim 4, wherein the a.c. voltage circuit components (4, 5) each comprise one Gr?tz rectifier circuit (D5; D6) whose a.c. input terminals form the connectors of the a.c. voltage circuit components (4, 5), and whose d.c. outputs are connected by a power semiconductor (T5; T6).
7. Device according to one of claims 4 to 6, wherein the two a.c. voltage circuit components (4, 5) form a factory-assembled hybrid module.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH3634/89-3 | 1989-10-04 | ||
| CH3634/89A CH679704A5 (en) | 1989-10-04 | 1989-10-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2042589A1 true CA2042589A1 (en) | 1991-04-05 |
Family
ID=4260200
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2042589 Abandoned CA2042589A1 (en) | 1989-10-04 | 1990-10-01 | Process and device for adjusting and controlling a.c. voltages from the public mains |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0452431A1 (en) |
| AU (1) | AU6433590A (en) |
| CA (1) | CA2042589A1 (en) |
| CH (1) | CH679704A5 (en) |
| WO (1) | WO1991005401A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2267788B (en) * | 1992-06-04 | 1997-01-29 | Strand Lighting Ltd | Dimming system, and dimmer therefor |
| DE4428682C2 (en) * | 1994-08-12 | 1997-01-23 | Robert Seuffer Gmbh & Co | Process for supplying an inductive load with sinusoidal alternating current and alternating current regulator therefor |
| EP1067671B1 (en) * | 1999-07-02 | 2003-02-19 | MAGNETEK S.p.A. | Power supply circuit of an electric motor and corresponding control method |
| EP1604440B1 (en) | 2003-03-14 | 2016-06-15 | ABB Technology AG | Electronic circuit breaker |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3354350A (en) * | 1964-10-27 | 1967-11-21 | Ohio Crankshaft Co | Two alternate conducting multivibrators powered by ac source |
| US4742441A (en) * | 1986-11-21 | 1988-05-03 | Heart Interface Corporation | High frequency switching power converter |
| US5455491A (en) * | 1987-10-14 | 1995-10-03 | Patricia Bailey | Power saving circuitry |
-
1989
- 1989-10-04 CH CH3634/89A patent/CH679704A5/de not_active IP Right Cessation
-
1990
- 1990-10-01 CA CA 2042589 patent/CA2042589A1/en not_active Abandoned
- 1990-10-01 AU AU64335/90A patent/AU6433590A/en not_active Abandoned
- 1990-10-01 EP EP19900914048 patent/EP0452431A1/en not_active Withdrawn
- 1990-10-01 WO PCT/CH1990/000232 patent/WO1991005401A1/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| AU6433590A (en) | 1991-04-28 |
| CH679704A5 (en) | 1992-03-31 |
| WO1991005401A1 (en) | 1991-04-18 |
| EP0452431A1 (en) | 1991-10-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |