Emergency power supply for lighting apparatus

Abstract

An emergency power supply for lighting apparatuses and to a lighting apparatus for an emergency power supply. The emergency power supply (1) includes: a power supply (11) provided with at least one main insulation, e.g., transformer, (34), operatively connectable to the network voltage; an accumulator (16) operatively connected to the power supply (11); a flyback power converter (17) including a primary (18) and a secondary (19) provided within at least one additional insulation, e.g., transformer (30). The primary (18) is connected to the accumulator (16) and the secondary (19) is directly connectable, except for the conversion network, to the output of a network power supply (2) and simultaneously to a light source (3). A control unit (20), which includes an transistor activation device (27), is operatively connected to the power supply (11), to the accumulator (16) and to the primary (18) of the flyback power converter (17) and is configured for detecting the network voltage and for switching the emergency power supply (1) between a first mode of deactivation of the flyback power converter (17) and a second mode of activation of the flyback power converter (17).

Claims

1. An emergency power supply apparatus for lighting apparatuses comprising: a power supply operatively connectable to a network voltage and including at least one main insulation; an accumulator operatively connected to the power supply; a flyback power converter including a primary having an electronic switch and a secondary, wherein the primary is connected to the accumulator and the secondary, provided within at least one additional insulation, is electrically and directly connected to cables between a network power supply and a light source of a lighting apparatus, due to the main insulation and to the additional insulation; wherein said flyback power converter is configured to directly transfer to an output circuit energy without switches/relay; a control unit operatively connected to the power supply, to the accumulator and to the primary of the flyback power converter and the control unit is configured to detect the network voltage and to switch the emergency power supply between a first mode of deactivation of the flyback power converter and a second mode of activation of the flyback power converter, wherein in the second mode, the flyback power converter works discontinuously at the switching frequency (f) of the electronic switch; wherein the control unit comprises an activation device configured to activate the flyback power converter; and wherein the activation device includes at least one transistor which switches the flyback power converter from the second mode to the first mode in response to the network voltage exceeding a predefined threshold.

2. The emergency power supply according to claim 1, further comprising an output diode operatively connected to the secondary of the flyback power converter and connectable by a wiring to the light source and to the network power supply.

3. The emergency power supply according to claim 1, comprising a capacitor operatively connected to the secondary of the flyback power converter and connectable by a wiring to the light source and to the network power supply.

4. The emergency power supply according to claim 3, wherein the capacitor is placed in parallel to the light source.

5. The emergency power supply according to claim 3, wherein an output diode and the capacitor are placed in series with an inductor of the secondary.

6. The emergency power supply according to claim 1, wherein the secondary of the flyback power converter is connectable by a shunt or a connector to the cables which lead from the network power supply to the light source.

7. The emergency power supply according to claim 1, wherein the control unit comprises a voltage detector operatively coupled to a secondary of the power supply and to the transistor, in order to bring to said transistor a signal proportional to the network voltage.

8. The emergency power supply according to claim 1, comprising a DC/DC controller operatively interposed between the control unit and the electronic switch of the flyback power converter.

9. The emergency power supply according to claim 8, further comprising a driver of the electronic switch of the primary of the flyback power converter, wherein said driver is operatively interposed between the DC/DC controller and said switch.

10. The emergency power supply according to claim 8, further comprising a detection device configured to detect a peak current (I) in the primary of the flyback power converter, wherein said detection device is operatively active on the primary of the flyback power converter and is operatively connected to the DC/DC controller to detect and adjust the power (P) sent to the light source.

11. The emergency power supply according to claim 1, comprising a capacitor placed between the primary and one of the terminals of output wires and configured for ensuring at least one additional insulation.

12. A lighting apparatus comprising: the network power supply; wherein the light source is connected to the network power supply through the cables; the emergency power supply according to claim 1; wherein the secondary of the flyback power converter of the emergency power supply is electrically and directly connectable or connected to the cables that connect the network power supply to the light source.

13. The lighting apparatus according to claim 12, wherein the emergency power supply comprises a preferential output connector connected to the secondary of the flyback power converter and connectable to a complementary connector present on the cables between the network power supply and the light source.

14. The lighting apparatus according to claim 13, wherein the emergency power supply comprises an auxiliary output connector connected in parallel to the preferential output connector.

15. A method to provide a lighting apparatus with an emergency power supply, the method comprising: providing a lighting apparatus comprising a network power supply and a light source connected to the network power supply; providing an emergency power supply comprising: a power supply operatively connectable to the network voltage and isolated from the network voltage by at least one main transformer; an accumulator operatively connected to the power supply; a flyback power converter comprising a primary having a transformer and an electronic switch, wherein the transformer includes a primary connected to the accumulator and a secondary; wherein said flyback power converter is configured to directly transfer to the light source electrical energy from the accumulator without a switch or a relay; a control unit operatively connected to the power supply, to the accumulator and to the primary of the flyback power converter and the control unit is configured to detect the network voltage and, in response to the detected network voltage, switch the emergency power supply between a first mode of deactivation of the flyback power converter and a second mode of activation of the flyback power converter, wherein in the second mode, the flyback power converter operates at a switching frequency (f) of the electronic switch; wherein the control unit comprises an activation device configured to activate the flyback power converter, and the activation device includes at least one transistor which switches the flyback converter from the second mode to the first mode in response to the network voltage exceeding a predefined threshold; and said method further comprising connecting, directly in parallel, the terminals of the secondary of the flyback power converter of the emergency power supply to cables which are extended between the network power supply and the light source.

16. The emergency power supply apparatus of claim 1 wherein the at least one main insulation includes a transformer and the at least one additional insulation includes a transformer.

17. An emergency power supply apparatus comprising: an emergency power supply including a first transformer having a primary winding configured to be connected to a network voltage source and a secondary winding; a battery connected to the secondary winding of the first transformer such that power from the network voltage source is applied to charge the battery; a flyback power converter including a second transformer having a primary winding connected to both the battery and the secondary winding of the first transformer and a secondary winding configured to be connected to a power input cable of a lighting source, wherein the power input cable is also configured to be connected directly to the network voltage source, and the connection between the secondary winding of the flyback power converter and the power input cable is without a switch or relay; and a controller configured to respond to a loss of power from the network voltage source by repeatedly switching on and off a connection between the battery and the primary winding of the second transformer.

18. The emergency power supply apparatus of claim 17 wherein the controller includes a driver configured to switch the connection at a switching frequency.

19. The emergency power supply apparatus of claim 17 further comprising a switch in series between the battery and the primary winding of the second transformer, wherein the controller is configured to actuate the switch to perform the repeated switching on and off of the connection.

Description

DESCRIPTION OF THE DRAWINGS

(1) Such description will be set forth hereinbelow with reference to the enclosed drawings, provided only as a non-limiting example, in which:

(2) FIG. 1 schematically illustrates a lighting apparatus provided with an emergency power supply according to the present invention;

(3) FIG. 2 illustrates in detail the diagram of the emergency power supply combined with the lighting apparatus;

(4) FIGS. 3 and 4 illustrate respective perspective views of the emergency power supply of FIG. 1;

(5) FIG. 5 illustrates an embodiment of the lighting apparatus provided with the emergency power supply.

DETAILED DESCRIPTION

(6) With reference to the above mentioned figures, reference number 1 overall indicates an emergency power supply according to the present invention.

(7) In FIG. 1, the emergency power supply 1 is combined with a lighting apparatus of conventional type comprising a network power supply 2 connectable to the power grid. The network power supply 2 is per se known and comprises an AC/DC converter. It is supplied with AC alternating current and feeds a light source 3, with which it is connected, with DC direct current. The light source 3 illustrated in the enclosed figures in a schematic manner is a LED module. Said light source 3 is connected by means of cables 4 (wiring) to the output terminals, not shown, of the network power supply 2. The emergency power supply 1 is connected, by means of suitable wiring in connection zone 6, to the cables 4 interposed between the network power supply 2 and the light source 3. The emergency power supply 1 is also connectable to the power grid.

(8) FIGS. 3 and 4 illustrate a box-like casing 7 of the emergency power supply 1 having a terminal board 8 for the connection to the power grid and to possible control elements. Also depicted in FIG. 5 is the wiring 5 exiting from the box-like casing 7 and terminating with a preferential (emergency) output connector 9 and an auxiliary emergency connector 35. In the embodiment illustrated in FIG. 5, a further additional wiring connects it to a signaling LED. Such preferential (emergency) output connector 9 is configured for being directly and safely coupled to a complementary connector 100 connected to the cables 4 at the connection zone 6, i.e. operatively arranged between the network power supply 2 and the light source 3. Such connectors 9, 100 are made so they can be easily coupled and uncoupled in a manual manner and preferably without the use of specific tools.

(9) The set of the network power supply 2 with the light source 3 and the emergency power supply 1 form a lighting apparatus 10 configured for operating as emergency lighting apparatus.

(10) With reference to FIG. 2, the emergency power supply 1 comprises a power supply 11 operatively connectable to the network voltage (e.g. 230 V) by means of the aforesaid terminal board 8. The power supply 11 is of AC/DC type and comprises a transformer with a primary 12, power supplied directly from the network voltage, and a secondary 13 connected to a battery charger 15. FIG. 2 illustrates diodes and a capacitor arranged in parallel with the primary 12. The circuit section connected downstream of the primary circuit is insulated therefrom with at least one main insulation 34 (insulation pursuant to the techniques of protection against electrical shock as in table 10.2 EN60598-1:2015 (V=2 U+1000V)).

(11) An accumulator 16, in battery form, is connected to the battery charger 15 and to the power supply 11.

(12) The emergency power supply 1 comprises a flyback power converter 17 (whose diagram is per se known). The flyback (recovery) converter 17 has switching power supply with galvanic isolation 30 between input and output equal to at least one additional insulation (insulation pursuant to the techniques of protection against electric shock as in table 10.2 EN60598-1:2015 (V=2 U+1000V)). The flyback power converter 17 comprises two coupled inductors. A primary 18 of the flyback power converter 17 is connected to the battery 16. A secondary 19 of the same flyback power converter 17, by means of the section composed of an output diode 21 and a capacitor 22, is connectable in parallel to the light source 3 by means of the wiring 5 and the connector 9.

(13) The output diode 21, the capacitor 22, the wiring 5 and the possible preferential emergency connector 9 are part of an interface device 14 at the network power supply 2 which is suitable to directly transfer, to the output circuit, the energy produced by the flyback converter 17 without the use of switches/relay.

(14) The emergency power supply 1 also comprises a control unit 20 operatively connected to the power supply 11, to the battery 16 and to the primary 18 of the flyback power converter 17.

(15) The control unit 20 carries out the function of switching the emergency power supply 1 between a first mode and a second mode (emergency phase).

(16) In the first mode, when the network voltage supplies the power supply 11, the flyback power converter 17 is deactivated. The light source 3 is continuously supplied (or can be supplied) through the network power supply 2. The power supply 11 of the emergency power supply 1 provides to charge the battery 16 by means of the battery charger 15.

(17) In the second (emergency) mode, when there is no network voltage, the flyback power converter 17 is activated by means of the control unit 20. In the second mode, the flyback power converter 17 provides over time to transfer the energy of the battery 16 to the light source 3. For example, the light source 3 is supplied with an electric power ranging from 1 to 30 Watt.

(18) More in detail, the flyback power converter 17 comprises the above mentioned output diode 21 and the capacitor 22 placed in series with the inductor of the secondary 19. The capacitor 22 is placed in parallel to the light source 3. The diode 21 and capacitor 22 assembly achieves the direct output current. In addition, the diode 21 achieves the protection of the system from the direct current coming from the network power supply 2 when this is turned on. A switch 23 is placed in series with the inductor of the primary 18 of the flyback power converter 17 and, when the flyback power converter 17 is activated or in the second mode, it opens and closes with a switching frequency f. In said second mode, the flyback power converter 17 works discontinuously with the switching frequency f of the switch 23 and brings energy quantities with said switching frequency f from the accumulator/battery 16 to the load/light source 3. The power is therefore converted and sent with open chain, i.e. without requiring control feedback, to the LED module 3.

(19) In the illustrated example, the switch 23 of the flyback power converter 17 is a MOSFET. The MOSFET switch 23 is driven by a driver 24 (which can comprise two transistors and a resistor).

(20) A detection device 25 of the peak current in the primary 18 of the flyback power converter 17 (e.g. a microcontroller and a suitable comparison circuit) is operatively active on said primary 18 and serves to detect said peak current I. A signal relative to the above mentioned peak current I is sent to a DC/DC controller 26 operatively interposed between the control unit 20 and the driver 24 of the MOSFET switch 23 in a manner so as to adjust the power sent from the accumulator 16 to the light source 3 when the flyback power converter 17 is activated. The detection device 25 in this manner determines the absorbed power P indirectly, and sends it to the light source 3. The estimation of such power P, except for the efficiency, is given by detecting the current peak I and the power P sent to the load is given by:
P=LI.sup.2f
with:
I peak current,
f switching frequency,
efficiency,
L inductance.

(21) In this manner, the circuit turns on the light source without feedback.

(22) In the embodiment illustrated in FIG. 2, the flyback power converter 17 also comprises an additional capacitor 36, of suitable value and insulation as in table 10.2 EN60598-1:2015 (V=2 U+1000V), placed between the primary 18 and the secondary 19 whose function is that of reducing the conducted emission problems present, since the two electrical domains (secondary of the flyback 17 and network power supply output 2 of the original apparatus) are shared.

(23) The control unit 20 comprises an activation device 27 intended to activate the flyback power converter 17 and a voltage detector 28. The voltage detector 28 is operatively connected to the secondary 13 of the power supply 11 and to the activation device 27, in order to bring, to said activation device 27, a fraction of the voltage at the secondary 13 of the power supply 11. The activation device 27 also carries out the function of comparator. If the voltage reported at the comparator 27 falls below a predefined threshold (e.g. 0.6 Volt), the activation device 27 activates the flyback power converter 17.

(24) In the illustrated embodiment, the comparator and activation device 27 is a transistor used as a switch, turned on when the network voltage exceeds a predefined threshold. The transistor 27 is used as a switch adapted to activate or deactivate the flyback power converter 17 by controlling the electrical conductivity of the transistor 27 itself by means of the application of a voltage between its terminals. The voltage detector 28 comprises a further transistor 29 and a capacitor. The circuit also has expedients for preventing thermic drift; for this reason, the Zener diode 31, the double diode 32 and the suitable resistive dividers are inserted.

(25) In other words, the control unit 20 is also comparator which detects the network voltage and activates the DC/DC controller 26 if the network voltage falls below or exceeds a certain threshold.

(26) With reference to FIG. 2, the power supply 11 of the emergency power supply 1 has a capacitor 33 placed in parallel with the secondary 13.

(27) The transistor 27 is turned on when the network voltage exceeds a certain level.

(28) On the cathode of the Zener diode 31, the fixed output voltage (of the electrolytic capacitor 33) is added with the peak of the network voltage reported at the secondary 13. This sum is divided and actively detected by the transistor 29 and reported at the input of transistor 27 which carries out the function of comparator with activation threshold at about 0.6V.

(29) Ignoring the drop Vbe of the transistor 29, if Vz=Vout (on the capacitor 33), at the input of the comparator 27 there is a voltage equal to Vin*K1 where:

(30) Where Ns is the number of secondary turns 13

(31) Where Np is the number of primary turns 12

(32) Once a suitable value of Kp is selected, one obtains the switching to the desired network voltage Vin.

(33) The conversion of the ordinary apparatus into an emergency apparatus is thus very simple. It will in fact suffice to provide the above-described emergency power supply and connect the preferential (emergency) output connector 9 to the complementary connector 100.

LIST OF ELEMENTS

(34) TABLE-US-00001 1 emergency power supply 2 network power supply 3 light source/LED 4 cables interposed between network power supply and light source 5 wiring 6 connection zone 7 box-like casing 8 terminal board 9 preferential emergency connector 10 emergency lighting apparatus 11 power supply section of the emergency power supply 1 12 primary power supply 13 secondary power supply 14 interface device 15 battery charger 16 accumulator/battery 17 flyback power converter 18 primary of the flyback power converter 19 secondary of the flyback power converter 20 control unit 21 diode of the flyback 22 capacitor of the flyback 23 switch of the flyback 24 driver of the switch 25 detection device of the peak current 26 DC/DC controller 27 transistor (activation device) 28 voltage detector 29 transistor of the voltage detector 30 additional insulation 31 Zener diode 32 double diode 33 capacitor 34 main insulation 35 auxiliary emergency connector 36 additional capacitor 37 additional wiring 38 signaling LED