Classifications

• • 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
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F29/00—Variable transformers or inductances not covered by group H01F21/00
  • H01F29/02—Variable transformers or inductances not covered by group H01F21/00 with tappings on coil or winding; with provision for rearrangement or interconnection of windings
  • H01F29/04—Variable transformers or inductances not covered by group H01F21/00 with tappings on coil or winding; with provision for rearrangement or interconnection of windings having provision for tap-changing without interrupting the load current

Definitions

• the present invention regards a programmable system for stabilising and regulating voltage, in particular for the improved management of lighting units using fluorescent bulbs and more generally those of the gas discharge type .
• this type of bulb to be switched on, requires a predetermined ignition voltage and that, when it has been switched on, after a period of heating which depends, amongst other things, upon the environment temperature, the supply voltage can be substantially reduced, still being kept above a predetermined minimum, which is necessary to avoid the light turn off.
• the light flow can be regulated, by varying the supply voltage, to adapt it to the user's requirements .
• management systems have been designed which take care of supplying such types of bulb with a regulated voltage, obtained from the mains, modulated to carry out the switching on and the heating of the bulbs in optimal conditions, then reduced and kept constant, independently from variations in the mains voltage, to obtain a predetermined light flow (also variable in time according to suitable programs) in conditions of optimal efficiency.
• the regulated supply voltage of the lighting unit is obtained with an autotransformer with many taps, selectively connected to the output one at a time, through switches controlled from a control and supervision station. Even if the use of solid state switches has been proposed, for reasons of cost and of safety the use of electromagnetic relays is generally preferred.
• the fine regulation of the output voltage requires, also by exploiting the known expedient of the reversing device, a high number of taps and of corresponding connection relays which it is desirable to reduce to the minimum.
• the by-pass circuits must dissipate the minimum power possible and at the same time ensure a voltage near to and preferably within the voltages which are switched, without for this reason requiring the use of a number of by-pass relays equal to the number of tap switching relays .
• figure 1 is a block diagram of the whole of a system for the optimised management of a lighting unit and of equipment comprising many systems
• figure 2 is a power module circuit diagram for the system of figure 1
• figure 3 is a circuit diagram of the detector devices of the state of the electromagnetic switches of the power module
• figure 4 is an exemplifying diagram of voltage/lighting which represents a preferred management method of the lighting in a tunnel with the equipment of figure 1
• figure 5 is an electrical diagram of a preferred embodiment of a photoresistor based brightness sensor and an auxiliary A/D conversion module for the system and equipment of figure 1.
• the system essentially comprises a control unit 1, with a microprocessor, a power module 2, with power section 2A and control section 2B, and a visualisation and command module 3 , with luminous indicators, display and keyboard.
• a control unit 1 with a microprocessor, a power module 2, with power section 2A and control section 2B, and a visualisation and command module 3 , with luminous indicators, display and keyboard.
• a manual or remote control switch 4 and a magnetothermic protection switch 5 the alternating voltage of the mains, in the figures nominally 225 V, is applied to the system.
• an AC/DC power supply feeder 7 connected to the mains through a transformer 6, supplies the control unit 1 and the control section 2B (through feed wires 80) with the required stabilised continuous service voltages (+5V, +12V) .
• the feeding of the control section is thus subordinated to the prior feeding of the control unit 1 which can verify the presence of the correct service voltage value applied to section 2B before controlling its intervention.
• the mains voltage, input to the power section 2A, is regulated so as to obtain in output a predetermined voltage value which is applied to a load Z, consisting of a bulb set, with the closing of an electromagnetic switch 18, controlled by the control unit 1.
• the control unit 1 and the control section 2B communicate through a channel 8, with serial or parallel interface .
• the control unit 1 instructs the control section 2B so that the voltage to be applied to the load takes on an appropriate value, for switching on, heating and maintaining such as to ensure a predetermined level of lighting, detected by a sensor 11.
• the different sensors and the possible auxiliary module are electrically decoupled from the control unit, both in terms of the power supply and in terms of the output signal, transmitted to the control unit 1 through optoelectronic devices 12 , 13 , 14.
• the control section 2B commands the power section to regulate the output voltage to the desired value and it controls it by means of a measuring transformer 16 which ensures the necessary feedback.
• An inner overheating protector can also be foreseen.
• section 2B operates as a slave to the commands of the control unit 1, to which all the necessary information is transferred.
• control unit 1 can be, and in general is, also equipped with communication interfaces (modem and/or serial ports) to receive commands or transmit data to a remote supervision centre.
• Figure 2 represents the structure of the power module 2A, 2B of figure 1 in greater detail, wherein the main (even if not exclusive) innovative aspects of the present invention are actually to be found.
• the power module comprises an inlet autotransformer 19 with inlet terminals N (neutral) and F (phase) to which the mains voltage, for example with a nominal value of 225 V, is applied.
• the autotransformer is equipped with an output terminal U to supply a load with a somewhat reduced nominal voltage equal to about 200 V which defines the average value of the regulation range in which the output voltage can be varied.
• the autotransformer is further equipped with a second group of N taps referenced in order as 24,25,26,27 (four in the preferred embodiment) upon which is available a nominal voltage, referred to the neutral potential, equal to 105,165,225,285V, respectively.
• the voltage between adjacent taps of the first group is nominally equal to 15V whereas the voltage between adjacent taps of the second group, as well as between the tap of the second group adjacent to the tap of the first group, is equal to M • 15V, that is 60 nominal volts.
• the taps of the first group are electrically spaced out on the winding of the autotransformer by K turns
• the taps of the second group are electrically spaced out by M • K turns, as are the electrically adjacent taps 24 and 23 of the first and of the second group respectively.
• the voltages available at the M+N output taps are selectively connected to the primary 28 of a voltage reducing auxiliary transformer 29, conveniently but not necessarily with a turn ratio close to 1/7, by means of two groups of electromagnetic switches 30, 31 and through a DPDT (Double Pole Double Throw) relay 32 with the function of reversing switch.
• a DPDT Double Pole Double Throw
• the secondary 33 of the transformer 29 is connected in series between the output terminal U of the autotransformer and the switch 18 for connecting to the load Z.
• the (nominal) range of variability of the regulated feed voltage of the load thus extends from about 159V to about 241V, which is more than sufficient to ensure an effective and regulated output voltage of between 175 and 215V also in the case of variations in the mains voltage of up to + 10% of the nominal voltage.
• the number of these circuits is less than the number of relays of each group: for the first group these consist of a single by-pass circuit, consisting of a relay 43 with the common pole connected to an intermediate tap 22 of the first group of tap and the contact which is normally open connected to the output node of the first group of relays through a current-limiting resistor 44.
• the value of the limiting resistors is suitably chosen to limit both the circulating current to acceptable values when a by-pass circuit is closed together with a relay of the corresponding group, and the voltage drop on the resistor, when the only by-pass circuit is closed and crossed by the feed current of the primary winding of the transformer 29 (which in the example described is a function of the load current in the ratio 1/7) .
• the resistor 47 can indicatively have a value of 20 ⁇ and the resistor 44 a value of 10 ⁇ .
• a further relay 48 which is normally open, is foreseen to short circuit the primary winding 28 of the transformer when the inverter switch is activated.
• the inverter switch is activated when the voltage applied to the primary 28 is zero, that is when the relays 37 and 42 are closed and consequently the primary is in short circuit.
• the primary 28 and the secondary 33 reverse their roles: the transformer is fed with current through the winding 33 which functions as a primary. Since the winding 28, which functions as a secondary, is in short circuit, the drop in voltage on the winding 33 is negligible (due only to resistance and dispersion reactance) .
• the transformer 29 behaves like an idle transformer, fed with current, that is as a reactance which introduces, as a function of the feed current, a high and unacceptable drop in voltage, at most limited by the saturation of the magnetic core, which significantly reduces the voltage applied to the load.
• control section 2B which comprises a microprocessor 49 with relative memory, driving circuits of the different relays and communication port with the control unit 1 (Fig.l) .
• control unit 1 To start up the system the control unit 1 firstly asks for a predetermined voltage to be supplied in output.
• the control section 2B after having measured the actual mains voltage available, determines, upon the basis of stored information, which of the relays of the first and of the second group must be closed and the position which the switch 32 must be in to obtain the desired voltage in output. Therefore, it commands their closing with a possible switching of the relay 32.
• the differential is less than a certain value (also programmable) it is indicated to the control unit 1 that it can proceed to the connection of the load with the closing of the switch 18. Otherwise it is necessary to modify the output value, in general with just the opening of a relay of the first group and the subsequent closing of another relay of the same group.
• a certain value also programmable
• control section 2B must verify, by means of circuits discussed later on, that the first switch is actually open before putting the second relay into closed state.
• More complex is the procedure to be followed to modify the output voltage under load, that is when the switch 18 is closed, both to keep the output voltage constant as the mains voltage varies, as well as to obtain in output a voltage which can vary according to a predetermined time profile established by the control unit 1 (ignition ramp, heating voltage, voltage reduction ramp, maintenance voltage) .
• the voltage set for the primary 28 is zero. It is necessary to then move closed the short circuit relay 48 and preferably, even if not necessarily, check the state thereof .
• the switching time of an electromagnetic relay is in the order of 10 ms, that switching procedures where a load is present require a non-negligible time, no less than 40 ms and than 80 ms when the switching of two relays of the first and of the second group is necessary.
• control circuits which allow the execution time of the procedures to be reduced to the minimum and which rapidly provide information that the different switching operations commanded have actually taken place.
• FIG. 3 shows a preferred embodiment of the circuits for checking the open/closed state of the switch contacts.
• the .contacts which are normally closed or inactive of the two switches 38,39 are connected to the inputs of a detector circuit 50 which provides in output a logic signal 1 asserted (for example a voltage of about 5V) when both of the switches are in rest position and a logic signal 0 when even only one of the switches 38,39 is switched with the common pole closing on the active pole.
• a logic signal 1 asserted for example a voltage of about 5V
• the structure of the detector circuit is very simple and comprises a rectifying bridge 51 connected to the inactive poles, which are normally closed, of relays 38,39, through a resistor 52 of a suitable value.
• the bridge feeds, in voltage rectified and filtered by a capacitor 72, through a second resistor 53, the light emitting diode of an optoelectronic coupler 54 whose phototransistor, connected between a suitable voltage (+5V) and ground, with a suitable resistance 55 in series with the emitter, imposes at the output, connected to the node between emitter and resistor 55, a logic signal 1 when the detector circuit is fed (that is, the switches 38,39 are both switched to open the active pole and to close the inactive pole) and a logic signal 0 when even only one of the switches is switched to close onto the active pole and therefore the detector circuit is not powered.
• the value of the resistor 53 and of the capacitor 72 is chosen so that the time constant RC of the circuit has . a predetermined value, in the order of 5ms.
• the value of the resistor 52 in relation to that of the resistor 53 is chosen according to the feed voltage (in our case 60 nominal volts being the effective value) so that the light emitting diode is energised with a suitable current, for example 10mA.
• the detector circuit 56 recognises the open state (level 1 as output) of both of the switches or the closed state (level 0 as output) of even only one of the switches .
• Substantially identical is also the structure of the detector circuit 57, with the only difference in the (lower) value of the resistor 52 within the circuit, to take account of the fact that the circuit has inputs connected respectively to the inactive pole of the switch 42 and to the tap with a nominal voltage of 30V so as to be fed (when the switch 42 is open) with a voltage of 15V.
• This circuit reveals the open or closed state of the only switch 42.
• the outputs of the detector circuits 50,56,57 are connected to the inputs of a NAND gate 58 which outputs a logic signal 0 when all of the switches of the first group 31 are open and a logic signal 1 when one of the group switches is closed.
• the information in output from the gate 58 and applied in input to the microprocessor 49 (Fig.2) is adequate to check the open/closed state of the switches and to verify if a switch (activated one at a time) has correctly responded to the closing and opening commands .
• the commands to close the switches of the same group are obtained by decoding a binary code, so as to rule out any possibility of commanding more than one switch of the same group to close simultaneously, due to an error or to a failure developed upstream of the decoder.
• the information received from the microprocessor is not just adequate but is also rapid.
• the feeding of the detector circuit which corresponds to the input signal, switches as soon as the inactive contact opens and before the closing onto the active pole takes place.
• the time constant of the detector circuit replaces the flight and bounce time of the mobile armature and ensures that the closing signal is received when the switching is definitely taking place and is about to be completed, without significant delays .
• the detector circuit is supplied with current as soon as the common pole closes on the inactive contact and the switching has definitely taken place .
• the detector circuit 57 Totally identical to the structure of the detector circuit 57 is the structure of the detector circuits 59,60 with inputs connected to the inactive poles of the relays 37,36 and 35,34 respectively and outputs connected to the inputs of a NAND gate 61.
• the NAND gate 61 like the gate 58, has in output a logic signal 0 when all of the relays of the group 30 are de-energised, thus open, and a logic signal 1 when one of the relays responds correctly to an energise command, closing itself.
• the detector circuits 62, 63 which respectively monitor the state of the by-pass relays 45,46 and the state of the by-pass relay 43.
• circuit 63 is identical to circuit 57 already described, receiving in input a voltage of 15V, and circuit 62, receiving in input a voltage of 120V, differs from circuit 50 only for the fact that it has a higher value of the internal resistance 52.
• circuits 62,63 arranged in logic NAND from gate 64, provide a logic signal 0 when all of the bypass circuits are open and a logic signal 1 when one of the by-pass circuits is closed.
• circuit 65 Although it is not indispensable, it is also possible to foresee a circuit 65 to detect the open or closed state of the short circuit switch 48.
• the structure of the detector circuit 65 is similar to that of circuit 50 and differs from the latter only because the former foresees, as well as the inversion of the output signal (obtained with the grounding of the phototransistor emitter and the connection of the output to the collector) , a Zener diode 66 in parallel with the capacitor 52.
• the Zener diode limits the current injected into the light emitting diode.
• the voltage applied in input can vary from 0 to 165V (a voltage of 165V is applied to one input and a variable voltage from 0 to 285V is applied to the other) .
• the outlet signal depends not just upon the open or closed state of switch 48 but also on the input voltage which can be 0 or so low (15+45V) as not to lead to the energising of the optoelectronic device.
• the ambiguity can be solved remembering that the short circuit relay can and must be moved closed only when switches 42 and 37 are both closed and the voltage of 45V referring to the neutral is applied to both of the poles of the inverter switch 32.
• the circuit receives in input a voltage of 120V, which is more than adequate.
• NAND gate 67 applies the logic signal 1 in input to gate 64 and masks the ambiguous states of the detector circuit 65.
• optimised management system was essentially considered as a voltage regulation system.
• the system described thanks to the fineness of regulation which is allowed (furthermore capable of being incremented even only slightly increasing the number of taps of the autotransformer and the corresponding number of relays) and thanks to the speed of response, can be conveniently used as a voltage stabiliser for the feeding of whatever type of load, as well as a programmable voltage regulator for feeding whatever type of load, the voltage of which must be regulated and possibly modified for whatever reason (for example for "margining" operations in a laboratory or to regulate the speed of motors fed in alternating current, replacing TRIAC partialising devices which do not allow the mains voltage to be increased and in particular have the serious drawback of introducing high width harmonics in the developed waveform.
• the described system can also operate as a brightness regulator, keeping in mind that the light emission is to a great extent dependent upon the feed voltage of the bulbs and the brightness of an environment also depends upon the possible variable light contribution coming from the outside. Therefore, a direct relationship between feed voltage and brightness of the room does not exist .
• the brightness sensor can also carry out a twilight function and the system can be programmed, obviously with suitable hysterisis, to switch on a light bulb when the brightness falls below a certain level, to keep the lighting at a desired level, in case variable according to time bands, and to switch off the light bulb if the brightness goes above another predetermined level .
• a specific application of this type consists of the regulation of lighting in tunnels.
• current lighting units for tunnels can consist of a line which is always switched on, known as "permanent" lighting, of a second low consumption line which is always switched on even in the case of a power cut since it is fed from UPS (Uninterrupted Power Supply) , known as tracing, and of a certain number of intensifying circuits (generally from 1 to 3 , according to the length of the tunnel) which switch on or off in relation to the brightness outside, to reduce glaring effects when leaving the tunnel and to allow the gradual adaptation to the lighting inside upon entering.
• UPS Uninterrupted Power Supply
• the system which has been described, appropriately replicated to constitute a piece of equipment, also effectively solves this problem and allows the brightness to be regulated gradually, with a high resolution, by controlling the selective intervention of the intensifying circuits according to the brightness outside.
• units B and C are each equipped, like unit A, with a central unit, such as 1, with at least one power module, such as 2, and with a keyboard, such as 3 , so as to be able to be programmed individually in a coordinated manner.
• a single keyboard, with a bus connection, represented by the dashed line 104 can be used to program the operation of the three units .
• the element common to the three units which completes the equipment consists of an auxiliary module 130 and of a brightness sensor 10 which, through the auxiliary module 130, sends a binary code, representing the level of brightness outside, to the three units on respective opto- insulated serial ports.
• auxiliary module 130 could allow the exchange of information between the different units A, B, C and the programming thereof with a single keyboard.
• Unit A can be programmed to manage the permanent line, unit B to manage the intensifying line or lines and unit C to manage the tracing line, all according to the brightness outside, measured with a single sensor 10.
• Figure 4 represents in a voltage V/external brightness level L qualitative diagram, a preferred form of regulation of the voltage for the different lighting lines.
• T a feed voltage which increases with the external brightness.
• the voltage can be different for the two lines but, for clearness of representation it is represented as equal .
• LI unit B When the external brightness is greater than LI unit B activates the feed of a first intensifying line RNF1, whereas the feed of the permanent line and of the tracing remain unchanged, as represented in the figures. If so desired, for very long tunnels or for particular requirements the feed voltage of the permanent and tracing lines could also be reduced and subsequently incremented.
• the feed voltage of the intensifying line is increased from LI and L2.
• the second intensifying line RNF2 is activated and the feed voltage of the other intensifying line is reduced.
• the third intensifying line RNF3, if present, is activated with the same criteria.
• a suitable hysterisis to reduce and remove the feed to the intensifying lines, in the case of reduction of external brightness.
• a lighting LTOT which can be varied gradually, without substantial discontinuities, with the level of brightness outside L, is obtained.
• the system object of the present invention uses a photoresistor, which is more cost-effective, more reliable and, being appropriately driven, allows greater precision of measurement and of regulation in all possible ranges of brightness .
• Figure 5 schematically represents the brightness measuring apparatus adopted.
• a photoresistor 10, remote from the regulation system, is connected to the auxiliary module 130 with a screened cable 78 which protects it to a large extent from disturbances and atmospheric discharges .
• the photoresistor 10 in parallel with a resistor 70 and in series with a resistor 71 which functions as a voltage divider, is fed by a continuous regulated and constant voltage of -5V.
• the node which is common to the photoresistor and to the resistor 71 is connected to the inverting input of an operational amplifier 74, with suitable feedback provided by a trimming resistor 75, to ensure a predetermined gain.
• Not-shown capacitors in a known way, filter the transient noise and cutting the frequency response of the amplifier.
• the output of the amplifier 74 is connected to an analogic input port of an integrated circuit for the acquisition and A/D conversion of signals which circuit outputs, on three serial ports, and sends to units A,B,C a binary code representing the input signal, in turn representing the resistance of the photoresistor 10 and, fundamentally, the measured level of brightness outside.
• the circuit can be programmed, to assign and characterise the ports with which it is equipped as analogue or digital input ports .
• the auxiliary module 130 is fed by an AC/DC power supply 79, connected to the output of the transformer 6
• the power supply 79 supplies the necessary continuous feed voltages to the module.
• This operation can be carried out in a very brief space of time, in the order of 100 ms, and it can be followed, in an equivalent time, by the restoration of the normal switching on conditions .
• the different switching relays can all be individually equipped with a switch detecting circuit, as is the case for relays 57 and 63 of figure 3, with outputs of the detector circuits arranged by groups in logic NAND or else connected directly to corresponding ports of the microprocessor, or even connected to a reduced number of ports and at the extreme to only one, through a multiplexer.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Control Of Electrical Variables (AREA)
• Micro-Organisms Or Cultivation Processes Thereof (AREA)
• Circuit Arrangement For Electric Light Sources In General (AREA)

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Citations (7)

• 2001
  • 2001-12-10 EP EP01830752A patent/EP1318702A1/de not_active Withdrawn
• 2002
  • 2002-12-06 AT AT02792914T patent/ATE357838T1/de not_active IP Right Cessation
  • 2002-12-06 WO PCT/EP2002/013818 patent/WO2003055283A1/en active IP Right Grant
  • 2002-12-06 DE DE60219066T patent/DE60219066T2/de not_active Expired - Lifetime
  • 2002-12-06 EP EP02792914A patent/EP1452076B1/de not_active Expired - Lifetime
  • 2002-12-06 AU AU2002358624A patent/AU2002358624A1/en not_active Abandoned

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