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
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
  • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
  • G05F1/10—Regulating voltage or current
  • G05F1/625—Regulating voltage or current wherein it is irrelevant whether the variable actually regulated is ac or dc
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P13/00—Arrangements for controlling transformers, reactors or choke coils, for the purpose of obtaining a desired output
  • H02P13/06—Arrangements for controlling transformers, reactors or choke coils, for the purpose of obtaining a desired output by tap-changing; by rearranging interconnections of windings
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
  • H05B41/14—Circuit arrangements
  • H05B41/36—Controlling
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
  • H05B41/14—Circuit arrangements
  • H05B41/36—Controlling
  • H05B41/38—Controlling the intensity of light
  • H05B41/40—Controlling the intensity of light discontinuously
  • H05B41/42—Controlling the intensity of light discontinuously in two steps only

Definitions

• the present invention relates to switching circuitry which permits the gradual, smooth progressive change up or down of the voltage output of a switching circuit. This prevents any sudden alteration in the voltage output of control circuitry for electrical and/or electronic equipment.
• the problem of smooth switching is particularly relevant when related to the economic use of fluorescent lights. On start up, for example, it is important that such lights or lighting systems be at full voltage. Afterwards however the voltage can be reduced to reduce power consumption.
• Prior art voltage controllers using a single autotransformer for each phase of a.c. power are known. Examples are shown in WO88/03353 (Econolight Ltd) for non-fluorescent lights; US Patent No 4219759 (Hirschfeld) for fluorescent lights on three phase power; US Patent No 4189664 (Hirschfeld) for fluorescent power on single phase power; and US Patent No 4513224 (Thomas) for fluorescent lights in which contacts are used to select the tappings of an autotransformer to reduce the voltage applied to the lighting load. In DE 3736324 voltage reduction is achieved by switching a choke in series with the lighting load.
• An object of the present invention is to provide a switching circuit which permits a ramp transition between a higher and a lower voltage level (ramping up and down) of a current, while the circuit is in operation,which circuits also overcome the disadvantages of the above prior art circuits.
• a further object of the invention is the provision of such circuitry for use with either a.c. or d.c. currents.
• the present invention provides an electrical switching circuit for ramp transition of the voltage output of said circuit between a higher and a lower voltage (or vice versa) , said circuit including: at least one variable resistor comprising a first solid state switch, an inductor and a resistor; and one or more second solid state switches; wherein one said variable resistor is connected to the conductance side of one said second switch; and wherein said circuit is connected to the voltage output of an autotransformer.
• each said first solid state switch is a field effect transistor ("FET") .
• FET field effect transistor
• the circuit includes at least one diode bridge rectifier of known type. The bridge rectifier is not necessary if the circuit includes two systems of switching circuitry in back to back configuration. However more complex control circuitry than would otherwise be used is then required.
• variable resistors are incorporated in said circuit.
• Each said second solid state switch may be of any known type, for example, a TRIAC switch.
• a capacitor is placed in parallel with the or each variable resistor to increasing the smoothing ability of said circuit.
• a.c. circuit includes three phase power, a circuit as described above and an autotransformer can be used on each phase.
• Fig. 1 is a circuit according to a first preferred embodiment of the present invention
• Fig. 2 is a circuit according to a second preferred embodiment of the present invention.
• FIG. 1 a first preferred embodiment of the present invention is thereshown.
• a voltage divider network maintains the secondary winding of the autotransformer (not shown) between the high and the low output modes.
• the circuit of Fig. 1 includes a FET 10, an inductor 11 and a resistor 12, which in series form a variable resistor 13.
• a capacitor 14 is arrayed in parallel with the variable resistor 13.
• Four diodes (D2-D5) form a bridge rectifier for a.c. current.
• Fig. 1 works as follows: the FET 10 is turned on, and the current through the inductor 11 and resistor 12 slowly builds up. If the FET 10 is then turned off the current will continue to flow through the inductor 11 and resistor 12 via a diode Dl. By adjusting the duty cycle of the FET 10 the current through the resistor 12 can be controlled. This variable current creates the same effect as a variable resistor.
• the capacitor 14 and resistor 12 also assist in damping out any harmonics generated within the circuit.
• the FET 10 can be switched on and off at a high frequency with the current smoothed by the operation of the inductor 11 and capacitor 14.
• a FET 10 is used in preference to a TRIAC switch (or other solid state switch) as it can be switched on and off at much higher frequencies.
• TRIAC switch or other solid state switch
• Other types of solid state switches may also be used, for example insulated gate bipolar transistors (IGBTs) .
• IGBTs insulated gate bipolar transistors
• a second preferred embodiment of the present invention is thereshown.
• the circuit contains two variable resistors (as described above) 23, 33 with FETS 20, 30 (and possible alternatives, as described above), resistors 22, 32 and inductors 21, 31, respectively) .
• Two bridge rectifiers with four diodes (D2-D5) are used in connection with each variable resistor (23, 33).
• Capacitors 24, 34 are also used in the manner described above with reference to capacitor 14. At point A the current must be controlled, it cannot float. The current must also be able to flow in both directions.
• variable resistor 23 is switched to the shorted mode (FET 20 is closed and FET 30 is open) .
• the TRIAC switch 25 is switched off.
• Variable resistor 23 ramps down to an off position.
• variable resistor 33 is ramped on and the TRIAC switch 35 is operated, shorting A to ⁇ .
• variable resistors 23, 33 can be turned off. This leaves the voltage output at the lower voltage level.
• the TRIAC switches 25, 35 then carry the permanent condition of the circuitry. If it is desired to raise the voltage to the higher level, the above described operations are reversed.
• the TRIAC switches 25, 35 may each or both be replaced with FETs (not shown) . These must be placed within the bridge rectifier for each variable resistor (23, 33) and connected between the positive and negative terminals of the respective bridge rectifier.
• the point E part way along the autotransformer can be moved to the end of the transformer, at point F.
• the TRIAC switches described above can be replaced with any other suitable switch.
• the inductors 14, 24, 34 may be any appropriate type (high impedance for a.c. current, low impedance for d.c. current).
• the size of resistors (12, 22, 32) used will depend on the power and voltage levels. For example, with moderate kilowatt power levels and mains voltage of 240 volts, 100 ohm resistors are appropriate. If so desired, any other resistor capable of handling the power and voltage in the circuit may be used.
• a suitable transition time for the movement of the voltage from one level to the other (in either direction) is approximately one second. If so desired, this time can be shorter or longer, depending on the capabilities of the resistors used.
• the order of the positioning of the inductors (11, 21, 31) and resistors (12, 22, 32) can be reversed.
• Other variants of the circuit arrangement are possible. Equally, the circuit can be configured in manners other than those shown in Figs. 1 and 2, and still obtain the same functional output from the circuit.
• the first preferred embodiment of the present invention can be used for control of a d.c. motor.
• the second preferred embodiment of the present invention can be used to control any electrical or electronic devices using a.c. current which, once switched on, can also operate at a lower voltage.
• An example of such devices is lights, especially fluorescent lights.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Automation & Control Theory (AREA)
• Electromagnetism (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Physics & Mathematics (AREA)
• Dc-Dc Converters (AREA)
• Rectifiers (AREA)
• Ac-Ac Conversion (AREA)
• Amplifiers (AREA)
• Noise Elimination (AREA)
• Oscillators With Electromechanical Resonators (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=19924387

Family Applications (1)

Country Status (10)

Cited By (1)

Citations (4)

Family Cites Families (5)

• 1993
  • 1993-06-17 NZ NZ247913A patent/NZ247913A/en unknown
• 1994
  • 1994-06-10 IL IL10998694A patent/IL109986A/xx not_active IP Right Cessation
  • 1994-06-14 CA CA002164819A patent/CA2164819C/en not_active Expired - Fee Related
  • 1994-06-14 EP EP94919015A patent/EP0704144A4/en not_active Withdrawn
  • 1994-06-14 IN IN506MA1994 patent/IN184266B/en unknown
  • 1994-06-14 AU AU70097/94A patent/AU673612B2/en not_active Ceased
  • 1994-06-14 WO PCT/NZ1994/000060 patent/WO1995001084A1/en not_active Application Discontinuation
  • 1994-06-16 ZA ZA944282A patent/ZA944282B/xx unknown
• 1995
  • 1995-12-11 NO NO955012A patent/NO955012D0/no unknown
  • 1995-12-14 FI FI956017A patent/FI956017A/fi not_active Application Discontinuation

Patent Citations (4)

Non-Patent Citations (1)

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