ES2364308B2 - PWM DIMMING SYSTEM IN HIGH FREQUENCY SERIES FOR APPLICATION IN SLOW DYNAMIC CONVERTERS FOR SOLID STATE MPARAS. - Google Patents

Abstract

High frequency serial PWM dimming system for application in slow dynamic converters for solid state lamps. dimming system (or dimming or regulation of the luminous flux) PWM in series at high frequency, for application in slow dynamic converters, even single stage with power factor correction or slow dynamic DC / DC converters, for lamps solid state such as OLEDs or PLEDs LEDs in which serial dimming is performed at a frequency comparable to the switching frequency of the converter. It is an electronic system for application in the artificial lighting sector.

Description

High frequency serial PWM dimming system for application in slow dynamic converters for solid state lamps.

The present invention refers to a dimming system (dimming or dimming of the luminous flux) of the luminous flux emission of solid state luminaires fed from electronic ballasts or even single-stage converters with power factor correction, or DC converters / Slow dynamic DC applying the serial dimming method performed at a frequency comparable to the switching frequency of the converter and with control of the peak current variation. It is an electronic system for its application in the field of artificial lighting.

Prior art

The luminaire luminous flux regulation system of the present invention relates to the most common PWM (Pulse Width Modulation) techniques used today. For the purposes of this invention and its description, as a solid-state luminaire, or luminaire, the entire assembly, including the electronic converter or ballast, the control system, regulation, communications and thermal dissipation regulation systems (active devices) ) -in case of being present-, and the lamp itself formed by the light emitting diodes, whether OLED, LED or PLED. As used herein, solid state lamp, or simply lamp, it should be understood only the part integrated by the light emitting devices and those passive thermal dissipation devices integrated with them.

The dimming, regulation or dimming of luminous flux of solid-state luminaires by PWM, consists of turning them on and off at a sufficiently high frequency, at least 100 or 200 Hz, although in many applications much higher frequencies are sought ( Svilainis, “LED PWM dimming linearity investigation”, Displays, Vol. 29, Num. 3, Jul., 2008, pages 243-249, ISSN 0141-9382), so that the human eye, by strobe effect, interprets it as a decrease in the luminous flux received. This regulation method is in contrast to what is known as dimming AM (Amplitude Modulation), consisting of the variation of the amplitude of the output current through the lamp. In the literature (Svilainis, “LED brightness control for video display application”, Displays, Yol. 29, Num. 5, Dec., 2008, pages 506511, ISSN 0141-9382), a clear preference for the method of dimming PWM, since the efficiency, colorimetric coordinates and tolerances in the operating characteristics of lamps such as solid state devices, vary with the value of injected current.

Among the PWM dimming methods included in the literature, three main methods can be established: a) dimming by Enable, in which a variable current reference is applied that causes the converter to operate in two states, on and off; b) dimming in series, whereby the load is opened and closed, that is, the lamp itself, in order to turn it on and off by means of a transistor arranged in series; and c) parallel dimming, whereby the load is short-circuited, by means of a transistor arranged in parallel with the lamp, in order to turn the load on and off alternately.

The objective of the PWM dimming methods is to feed the light emitting diodes with a pulse train of variable width and whose peak value is the nominal value of direct current in operation without dimming, so that the colorimetric characteristics are not they are affected, and the light emission is regulated with the pulse width of the pulse train, that is, with the time the lamp is on in relation to the dimming switching period of the output current. Said light regulation also has the characteristic that it is proportional to the pulse width applied to the lamp.

The above-mentioned PWM dimming methods apply to DC / DC converters (from continuous to continuous) controlled by current, either by averaged current, peak current, driving / blocking time or hysteresis, because these configurations provide a dynamic fast enough to perform Enable dimming without major technical complications, or have current source behavior to perform parallel dimming, or almost instantly follow the current reference without the need for any compensation network, to perform serial dimming without oscillations

In the case that concerns the field of application of this invention, that is, for the dimming of electronic converters or ballasts to power lamps from the AC network, whether domestic, industrial, public lighting, etc. at the different voltages and frequencies used internationally (or even continuous if they were extremely slow converters), the slow dynamics that characterize them, with a bandwidth always less than twice the grid frequency (or in the case of converters of continuous, with a bandwidth several decades lower than the switching frequency), it implies the impossibility of applying the methods described above, since: a) in the case of enable dimming, the converter is not fast enough as to ensure the complete on and off of the lamp, losing linearity in the dimming and performance. Although your response was fast enough to perform dimming by Enable, the dimming frequency must be very high so as not to excessively penalize the harmonic content of the input current, which is in the same situation; b) in the case of serial dimming, there is the same problem of slow dynamic response or oscillation of the converter is caused; and c) in the case of parallel dimming, the output or bus capacitor is being short-circuited, an essential component in power factor corrective circuits to fi lter the double frequency grid curling, thus causing overcurrents through the emitting diodes of light, which could cause your failure.

Due to the above, the most commonly used solutions are: a) for low-power ballasts connected to the mains, either with power factor correction or without such function, dimmers are used as those used with incandescent lamps using thyristors -DIAC or TRIACS- (Rand et al, “Issues, Models and Solutions for Triac Modulated Phase Dimming of LED Lamps”, IEEE Power Electronics Specialists Conference (PESC) Proceedings, pages 1398-1404, Jun., 2007) suitably modified, to vary the conduction angle of the input current, and b) a second cascade stage is added to improve the dynamic response of the converters and to be able to implement another type of control in the second stage that allows the use of any dimming technique of a simple and reliable way, as well as other alternatives (García et al “An Alternative to Supply DC Voltages with High Power Factor”, IEEE Transactions on Industri to Electronics, Vol. 46, Num. 4, Aug., 1999) in which complex topologies with two or more converters with several outputs and / or bus capacitors are proposed. The main drawback of the first solution is that the dimming achieved in this way, if you want to maintain the simplicity of the power circuit without adding additional cascade stages, is by amplitude variation, that is, dimming AM, being also only viable in the case of low powers; while in the second case, heavier converters are obtained by having two stages, with two transistors, two coils, etc., which result in greater cost and size and lower performance, in addition to complicating the regulation loop with a circuit of control for each stage. In the last case mentioned, more complex topologies are obtained, with a greater number of components and cost.

However, to achieve a ballast that in addition to performing power factor correction, has a dynamic enough to perform dimming, combined with a lower cost than in the case of cascading converters, it is usual to combine these two stages in one, sharing a switch, what is known as integrated converters. As a counterpart to the integration, the electrical stress and / or current efforts on the shared active switches increase, which leads to increased losses and the use of semiconductors of greater price and technical complexity. An example of an integrated converter for feeding metal halide lamps is found in Dalla Costa et al (pat. No. ES2296459). However, in order to apply the dimming by Enable to integrated converters, a control loop must be designed to provide the ballast with a dynamic response fast enough and without affecting the input current wave in terms of harmonic content. In case of applying dimming in series or parallel to these converters, the problems already mentioned would be presented, since to eliminate low frequency curling, they have an output capacitor in parallel with the load.

Description of the invention

The present invention refers to a PWM dimming system for application in electronic converters or slow dynamic ballasts for feeding solid-state lamps, such as single-stage power factor correctors that, fed from the alternating current network , provide the solid state lamp power in the form of direct current complying with IEC61000-3-2.

The serial PWM dimming system for solid-state lamps comprises:

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A switched power converter, and an input EMI filter. The switched power converter has its slow closed loop dynamics, which prevents it from dimming by Enable fast enough to achieve satisfactory performance. The EMI fi lter in turn comprises two capacitors between phase and neutral (or between positive and supply ground in the case of a converter connected to a continuous power bus), and a coil located in the phase (or positive in case of continuous buses) whose terminals are connected to a terminal of both capacitors, which acts as an interference suppressor to eliminate or attenuate any type of radioelectric disturbance of lighting equipment and the like. For converters connected to the alternating network, a full-wave rectifier bridge, consisting of 4 diodes, is available in order to obtain a continuous voltage wave equivalent to the rectified alternating voltage by means of an unregulated full-wave rectifier. Two of the rectifier diodes are connected in common cathode, while the other two are connected in common anode. Those that are connected in common cathode are arranged connected by their cathodes to the positive input terminal of the rectifier, while those connected in common anode are connected to the ground terminal of the converter through its anodes. In the case of converters connected to DC power buses, the most positive terminal of the power supply network is connected to the positive input terminal of the converter, while the most negative power terminal (or ground) is connected to the terminal of mass of the converter. Converters with power factor correction, that is, those connected to the AC network, have a bus capacitor at their output, designed to store high frequency energy and, in addition, filter the low frequency alternating component from the rectified wave with which the converter is powered, being responsible for the slow dynamics of this type of switched sources. Said bus or output capacitor is connected between the positive and negative output terminals of the converter, so that the positive terminal of the capacitor is connected to the positive output terminal, and the negative terminal of the capacitor is connected to the negative output terminal of the converter. In turn, the positive terminal of the bus capacitor is connected to the positive terminal, or input terminal, of the solid state lamp.

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A solid state lamp.

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An auxiliary switch arranged in series with the solid state lamp through which the dimming function is performed. The dimming is carried out by means of an auxiliary switch, working in cut and saturation to turn on and off the solid-state lamp, arranged in series with it, whose active input-drain terminal in the case of MOSFET transistors and collector in the case of The BJT transistors are connected to the output terminal of said solid state lamp. The active output terminal of the switch - source in the case of MPSFET transistors and emitter in the case of BJT transistors - is connected to the input terminal of the current measurement block.

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A current measurement block to measure the current flowing through the solid state lamp. The output terminal of the current measurement block is connected to the negative terminal of the switched power converter and the negative terminal of the bus or output capacitor.

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A main oscillator block that generates the high frequency signal that is used for transistor governance

or transistors of the switched power converter.

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A dimming level selector block that allows you to select the dimming level.

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A PWM pulse generator block for dimming that generates the dimming signal from the signals coming from the dimming level selector block and the main oscillator block. In the PWM pulse generator block for dimming, the steering pulses for the auxiliary switch are generated from the previous blocks. Said PWM pulse generator block for dimming generates a high frequency signal with variable pulse width, which is subsequently applied to the auxiliary switch driver. The variable pulse width signal from the PWM pulse generator block is also applied to the dimming measurement block to determine the level of dimming required by the user.

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An auxiliary switch driver that transmits the dimming signal generated by the PWM pulse generator block for dimming to the auxiliary switch. The driver generates the control signal of the auxiliary switch control terminal, gate in the case of MOSFET transistors and base in the case of BJT transistors.

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A dimming measurement block that measures the dimming level selected by the user if necessary.

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A current reference generator block that generates the current reference for the closed chain luminaire control loop from the signal coming from the dimming measurement block. The reference generator block multiplies the signals, thus generating the new current reference with which the control loop operates.

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A regulator block that generates a control signal from the error signal obtained by subtracting the signal from the current measurement block of the signal from the current reference generator block. The signal generated by the current reference generator block, that is, the current reference of the regulation loop, is applied to the regulator block, which performs the subtraction between this signal and that from the current measurement block to generate a signal error that:

a) In the case of averaged current control or voltage mode control, it will be the error signal that, once modified by the regulator, is the one that determines the duty cycle of the steering pulses of the main transistor of the power converter commuted, according to control theory.

b) In the case of peak current control, the regulator block generates the current reference signal for the internal regulation loop, which is processed together with the current flowing through the main transistor of the switched power converter for determine the pulse width of the steering signal of the main transistor of the switched power converter.

In the series PWM dimming system for solid state lamps of the invention, the switching of the auxiliary switch, and consequently, the PWM dimming, is performed at high frequency and in addition the switched power converter is slow dynamic. For the purposes of the present invention and its description, high frequency should be understood as those frequencies of the same order of magnitude as the switching frequency of the power transistor or transistors that the converter is operated on, said frequencies being always higher than the frequency corresponding to the bandwidth that characterizes the converter used in closed loop.

In a specific embodiment, the switched power converter is a single stage AC / DC converter with a bandwidth less than twice the network frequency, or an integrated AC / DC converter whose bandwidth is at least two decades less than the switching frequency, or a two-stage AC / DC converter whose bandwidth is at least two decades less than the switching frequency, or a DC / DC converter whose bandwidth is at least two decades less than the switching frequency

In another specific embodiment, the switched power converter operates in voltage mode or in current mode, connected to the alternating power network or to DC power buses, in any of the following driving modes: Continuous Driving Mode, Power Mode Driving Discontinuous or in Border Driving Mode, at fixed or variable frequency. In a more specific embodiment, the switched power converter operates in current mode, and incorporates a medium current control, with a single regulation loop. In an even more specific embodiment, the control signal from the regulator block is used to generate the steering pulses of the main transistor of the switched power converter, thus implementing a closed loop control system in medium current mode. In another more specific embodiment, the switched power converter operates in current mode, and incorporates a peak current control, with an external regulation loop, and an internal regulation loop. In another even more specific embodiment, the control signal from the regulator block is used to generate a control signal that is complemented by the peak current reading of the main transistor of the switched power converter, thus implementing a control scheme by peak current, where the regulator block represents the regulator of the external control loop, considering the internal control loop as internal to the switched power converter.

In a preferred embodiment, the solid state lamp is at least one LED, an OLED, or a PLED. In a more preferred embodiment, the solid state lamp comprises means of heat dissipation by natural or forced convection.

In another preferred embodiment, the current measurement block performs the fi ltration of the high frequency components of the output current that is fed back to the regulator block. In a more preferred embodiment, serial dimming is executed at a frequency of the same order of magnitude as the converter switching frequency, so that the regulator acts on the average value of the pulsed current modifiable by the dimming duty cycle.

In another preferred embodiment, the current measurement block reliably transmits the output current to the regulator block. In a more preferred embodiment, serial dimming is performed at a frequency of the same order of magnitude as the converter switching frequency, so that the pulsing current is interpreted as high frequency disturbances and filtered by the closed-loop regulation loop. .

In another preferred embodiment, the system further comprises a frequency divider block that generates the high frequency signal used to perform the dimming and is applied to the PWM pulse generator block for dimming, from the signal generated by the main oscillator block to perform dimming at frequencies below the switching of the switched power converter.

In a more preferred embodiment, the frequency divider block is implemented with analog, digital components and / or by program function blocks or software programs.

In another more preferred embodiment, the system further comprises a current selector block, whereby the user selects the level of direct current in normal operating mode, and the peak level in dimming operation mode. The dimming level signal from the dimming measurement block is applied to the current reference generator block together with the signal from the current selector block, which is responsible for setting the direct current level in case of operation without dimming , and the peak output current level in case of operation in dimming mode. In an even more preferred embodiment, the dimming level selector block is implemented with analog, digital components, and / or by program function blocks or software programs. In another even more preferred embodiment, the user accesses the dimming level selector block (15) manually or by means of commands issued through communications networks. In another even more preferred embodiment, the system feeds the solid state lamp by means of a square current wave with modifiable pulse width, whose minimum value is null and whose peak value is user selectable. In another even more preferred embodiment, the current reference generator block generates the current reference for the closed-loop regulation loop from the signals coming from the dimming measurement block and the current selector block.

In another more preferred embodiment, the switched power converter operates in voltage mode or in current mode, connected to the alternating power network or to DC power buses, in any of the following driving modes: Continuous Driving Mode, Mode Driving Discontinuous or in Border Driving Mode, at fixed or variable frequency. In an even more preferred embodiment, the switched power converter operates in current mode and incorporates a medium current control with a single regulation loop. In an even more preferred embodiment, the control signal from the regulator block is used to generate the steering pulses of the main transistor of the switched power converter, thus implementing a closed loop control system in medium current mode. In another even more preferred embodiment, the switched power converter operates in current mode and incorporates a peak current control with an external regulation loop and an internal regulation loop. In another even more preferred embodiment, the control signal from the regulator block is used to generate a control signal that is complemented by the peak current reading of the main transistor of the switched power converter, thus implementing a control scheme. by peak current, where the regulator block represents the regulator of the external control loop, considering the internal control loop as internal to the switched power converter.

In a more specific embodiment, the solid state lamp is at least one LED, an OLED, or a PLED. In an even more specific embodiment, the solid state lamp comprises means of heat dissipation by natural or forced convection.

In another more specific embodiment, the current measurement block performs the filtering of the high frequency components of the output current that is fed back to the regulator block. In an even more specific embodiment, serial dimming is executed at a frequency of the same order of magnitude as the converter switching frequency, so that the regulator acts on the average value of the pulsed current modifiable through the dimming duty cycle .

In another more preferred embodiment, the current measurement block reliably transmits the output current to the regulator block. In an even more preferred embodiment, serial dimming is performed at a frequency of the same order of magnitude as the converter switching frequency, so that the pulsing current is interpreted as high frequency disturbances and filtered by the chain regulation loop closed.

In a specific embodiment, the system further comprises a current selector block by which the user selects the level of direct current in normal operation mode, and the peak level in dimming operation mode. The dimming level signal from the dimming measurement block is applied to the current reference generator block together with the signal from the current selector block, which is responsible for setting the direct current level in case of operation without dimming , and the peak output current level in case of operation in dimming mode.

In a more specific embodiment, the dimming level selector block is implemented with analog, digital components, and / or by program function blocks or software programs. In another more specific embodiment, the user accesses the dimming level selector block manually or by means of commands issued through communications networks. In another more specific embodiment, the system feeds the solid state lamp by means of a square current wave with modifiable pulse width, whose minimum value is null and whose peak value is user selectable. In another more specific embodiment, the current reference generator block generates the current reference for the closed-loop regulation loop from the signals coming from the dimming measurement block and the current selector block.

In another more specific embodiment, the switched power converter operates in voltage mode or in current mode, connected to the alternating power network or to DC power buses, in any of the following driving modes: Continuous Driving Mode, Mode Driving Discontinuous or in Border Driving Mode, at fixed or variable frequency. In an even more specific embodiment, the switched power converter operates in current mode and incorporates a medium current control with a single regulation loop. In an even more specific embodiment, the control signal from the regulator block is used to generate the control pulses of the main transistor of the switched power converter, thus implementing a closed loop control system in medium current mode. In another even more specific embodiment, the switched power converter operates in current mode and incorporates a peak current control with an external regulation loop and an internal regulation loop. In another even more specific embodiment, the control signal from the regulator block is used to generate a control signal that is complemented by the peak current reading of the main transistor of the switched power converter, thus implementing a control scheme. by peak current, where the regulator block represents the regulator of the external control loop, considering the internal control loop as internal to the switched power converter.

In a more preferred embodiment, the solid state lamp is at least one LED, an OLED, or a PLED. In an even more preferred embodiment, the solid state lamp comprises means of heat dissipation by natural or forced convection.

In another more preferred embodiment, the current measurement block performs the fi ltration of the high frequency components of the output current that is fed back to the regulator block. In an even more preferred embodiment, serial dimming is performed at a frequency of the same order of magnitude as the converter switching frequency, so that the regulator acts on the average value of the pulsed current modifiable by the dimming duty cycle .

In another more preferred embodiment, the current measurement block reliably transmits the output current to the regulator block. In an even more preferred embodiment, serial dimming is performed at a frequency of the same order of magnitude as the converter switching frequency, so that the pulsing current is interpreted as high frequency disturbances and filtered by the chain regulation loop closed.

In a specific embodiment of the system, both with the frequency divider block or the current selector block or without them, the auxiliary switch is a bipolar transistor, MOSFET or IGBT, with its active input terminal connected to the cathode of the last diode of the solid state lamp, with its active output terminal connected to the input terminal of the current measurement block, and whose control terminal receives, through a driver, the dimming signal generated in the PWM pulse generator block for dimming .

In a preferred embodiment of the system, both with the frequency divider block or the current selector block or without them, the current measurement block is implemented with analog, digital components and / or by program function blocks or software programs.

In a specific embodiment of the system, both with the frequency divider block or the current selector block or without them, the main oscillator block is implemented with analog, digital components and / or by program function blocks or software programs.

In another specific embodiment of the system, both with the frequency divider block or the current selector block, as well as with them, the PWM pulse generator block for dimming is implemented with analog, digital components and / or through program or program functional blocks. software.

In another specific embodiment of the system, both with the frequency divider block or the current selector block or without them, the auxiliary switch steering driver consists of discrete components or specific integrated circuits.

In a preferred embodiment of the system, both with the frequency divider block or the current selector block, or without them, the dimming measurement block is implemented with analog, digital components and / or by program function blocks or software programs.

In another preferred embodiment of the system, both with the frequency divider block or the current selector block or without them, the current selector block is implemented with analog, digital components and / or by program function blocks or software programs.

In another preferred embodiment of the system, both with the frequency divider block or the current selector block or without them, the user accesses the current selector block manually or by means of commands issued through communications networks.

In a specific embodiment of the system, both with or without the frequency divider block or the current selector block, the current reference generator block is implemented with analog components, specific integrated circuits, digital components and / or through functional blocks of program or software programs.

In another specific embodiment of the system, both with or without the frequency divider block or the current selector block, the regulator block that implements the closed chain control loop is analog.

In another specific embodiment of the system, both with or without the frequency divider block or the current selector block, the regulator block that implements the closed chain control loop is digital.

In another specific embodiment of the system, both with the frequency divider block or the current selector block and without them, the solid state lamp is fed by a square current wave with modifiable pulse width, whose minimum value is null and whose Peak value is a system design parameter not selectable by the user.

In a preferred embodiment of the system, both with or without the frequency divider block or the current selector block, the average value of the current wave that feeds the solid state lamp is proportional to the time in which its value is not null in relation to the dimming switching period.

In another preferred embodiment of the system, both with the frequency divider block or with the current selector block, the peak value of the output current is kept constant regardless of the dimming duty cycle used, by compensating the value peak output current by modifying, by means of the current reference generator block, the current reference of the switched power converter.

The current wave demanded from the power grid by the converter when it is operating in the light fl ow or dimming mode retains the shape of the alternating current wave of normal operation, although with an effective value proportional to the flux attenuation Luminous realized. This system takes advantage of the slowness of the converters by switching the lamp, that is, by opening and closing the load circuit, at a frequency such that the closed-loop system is not able to respond to such disturbances, perceiving only a decrease in the average value of the output current that is to be compensated by increasing the peak value, which is why the current reference must be modified. The dimming switching frequency must be much higher than the open loop gain crossover frequency, offering optimal operation in terms of waveform when the switching frequency and the dimming frequency are coincident and also synchronized. In this way, the main problem of power factor correction converters and slow dynamic converters in general is solved, which is none other than their slow dynamics, or small bandwidth, which prevent the application of the three techniques of dimming usually used and collected in the state of the art, such as dimming by Enable, dimming in series and dimming in parallel. Without the application of the system proposed by the invention, dimming by Enable should be performed at frequencies below 200 Hz, so that the eye would perceive the lamp flickering; in case of applying dimming in series, the circulation of high current peaks through the light emitting diodes of the lamp would be generated, in addition to causing the oscillation of the regulator leading to a great risk of destruction of the different parts of the luminaire; and in the case of parallel dimming, large voltage fluctuations in the load and the circulation of high currents in the dimming transistor would be caused due to said effect, also entailing a serious risk of destruction of the different parts of the luminaire.

The proposed light fl ow regulation system must perform several functions due to the unique operating characteristics derived from the action on the load at a much higher frequency than the converter is capable of responding. In this way, the control system performs the following functions: a) perform the on and off of the solid state lamp; b) measure the current flowing through the solid state lamp; c) generate the steering pulses of the dimming device; d) select and measure the level of operation dimming; e) select the operating peak current level; f) generate a reference signal that compensates for the decrease in the average value of current measured during dimming operation; g) generate an error signal that is applied to a traditional regulation loop in medium current mode or any other current control system, such as peak current control or even variable frequency current regulation systems.

The operation of the serial PWM dimming system proposed in the invention is as follows for the version that allows the selection of the output current level, described above, both with voltage mode control

or medium current, as for peak current control. In the case of operation in dimming mode, the auxiliary switch switches the solid-state lamp to high frequency, performing dimming PWM, that is, forcing the current flowing through the solid-state lamp to consist of a square wave whose minimum value is null, its peak value is selectable and modifiable by the user, and its average value depends on the pulse width, that is, on the proportion in which the current is non-zero compared to the total dimming switching period, parameter selectable and modifiable by the user. The current measurement block processes the output current to send the information obtained to the regulator block.

On the other hand, as regards the version with a fixed peak current level, such as the one shown in Fig. 1B where the system does not include the current selector block, the operation is similar to that previously described for the version with a value of Modifiable peak for both control systems contemplated: by classical control theory and for peak current control. In operation with dimming, the auxiliary switch switches the solid-state lamp to high frequency, performing dimming PWM, that is, forcing the current flowing through the solid-state lamp to consist of a square wave whose minimum value is zero , its peak value remains constant and equal to the design speci fi cations and its average value depends on the pulse width, that is, on the proportion in which the current is non-zero compared to the total dimming switching period, selectable parameter and modifiable by the user. The current measurement block processes the output current to send the information obtained to the regulator block.

There is the fact that due to the high frequency at which the dimming is performed, applied to a slow dynamic converter, the regulating block can only act on the average value of the signal fed back by the measuring block, which corresponds with the average value of the output current. There are two supposed cases depending on the configuration of the light fl ow regulation system:

a) If the current measurement block incorporates dynamics, that is, it filters the output current, its average value is fed back to the regulator block.

b) If the current measurement block does not incorporate dynamics, that is, if it transmits the information to the regulator block exactly as it receives it, the arrangement of poles and zeros of the regulator block, which entails extremely slow dynamics - both in the case of control by averaged current, as in the case of control by peak current, in which case the external regulation loop is the one contemplated in this invention - causes the impossibility of the regulating block to act at the dimming frequency, acting only before variations in the average level of the output current.

If a current measurement block with dynamics is incorporated, the dimming frequency may be lower in the case of not having dynamics in said block, since the average value of current is fed back by the load, acting on it, instead of dimming at a frequency to which the regulation loop is not able to respond. However, the slow dynamics necessary for the first case can lead to instability in closed loop or added complications in the design of the regulator.

In both cases, the regulator block acts by increasing the output current in order to match the average current value measured by the current measurement block with the original reference, the result being an increase in the peak value that must be compensated in later stages of the dimming regulation loop by decreasing the reference level of the output peak current.

In the version of the invention that allows the modification of the current peak level, such as that shown in Fig. 1A, said compensation is performed by the current reference generator block, multiplying the current reference value and the level of dimming selected by the user, thus generating the internal current that will be applied to the regulator block.

On the other hand, in the version with a fixed peak current level, such as the one shown in Fig. 1B, this compensation is carried out by means of the current reference generator block, multiplying the dimming level selected by the user by a predefined gain in the design, so that the generated current reference corresponds to the desired peak output current value.

In both versions of the invention, the dimming level is selected by the user through the dimming level selector block. The dimming frequency is defined by the pulse generator block for dimming, which acts as a frequency divider of the high frequency signal generated by the main oscillator block, the dimming frequency being much higher than the converter's gain crossover frequency in open loop. Subsequently, the PWM dimming signal is applied to the auxiliary switch driver so that it switches the solid state lamp. This driver is expendable if the appropriate components are used. The steering signal of the auxiliary switch is characterized by the variable pulse width, which determines the level of attenuation of the brightness of the solid state lamp according to the level of attenuation introduced by the user.

This invention is applicable both to converters controlled by averaged current, where the control loop itself is modified as set forth, and to converters controlled by peak current, where the external regulation loop is modified as contemplated in the present invention. , considering the internal regulation loop as an internal aspect of the converter, considered the same generic block.

The invention has important advantages over the most common dimming techniques discussed in the state of the art. First of all, the possibility of applying the invention to converters with single-stage power factor correction allows to build electronic ballasts, or power converters, with a small number of components, since it is possible to process power to perform correction of factor of power with just an active switch, a transformer, a diode and an electrolytic capacitor, which would correspond to a Flyback converter, hardly complicating the control circuit. In this way the development of two-stage converters is avoided, in which one of them performs the correction of the power factor and the subsequent stage, cascaded, processes the power and performs the dimming, which are much more bulky, heavy and expensive than single-stage converters, and have worse performance when processing power twice for each switching cycle.

Another advantage of high frequency dimming or dimming is the elimination of visible flickering,

or fl ickering, perceptible with certain low frequency dimming techniques and which can be especially annoying for a certain percentage of the population or can pose problems with image capture systems, such as television or video cameras.

In addition, the elimination of emissions in the audible spectrum by humans (between 20 Hz and 20 kHz) is added in case of selecting dimming frequencies above the audible upper limit.

The field of application of the present invention is that corresponding to all types of artificial lighting regulation systems based on light emitting diode lamps, whether LED, OLED or PLED diodes.

The proposed dimming system can be used for the power supply from any electrical network of lamps for general lighting systems, both indoor and outdoor, industrial, environmental lighting, public lighting, photographic studies, television, sports facilities, domestic applications, etc. . It can also be used with power from DC networks.

Due to its applicability to single-stage converters, it is very suitable to be incorporated in luminaires of small size in which it is necessary to regulate the emission of luminous flux, or in those where aesthetic or design restrictions impose the small ballast size .

On the other hand, and since it can be adapted to any electronic converter, it is applicable to the entire range of powers that are handled in solid state lighting.

Description of the fi gures

Fig. 1 represents the diagram, in block diagram, of the dimming system object of the invention. Fig. 1A represents one of the proposed versions, in which it is possible to select the peak current level, while Fig. 1B represents the version in which the peak current level is predefined and is not modifiable.

In Fig. 1A, at the block level, the circuit necessary to perform PWM dimming is shown with the possibility of selecting the output peak current level, integrated by the auxiliary switch (11) and its driver (17); the switched power converter (1), also considering the bus or output capacitor (9); the solid state lamp (10); the main connection of the converter to the power grid, consisting of phase (F) and neutral (N) for the alternating network, and positive (+) and negative (-) power for DC buses, consisting of the EMI filter consisting of the capacitors (2) and (4) and the coil (3), and the diodes (5), (6), (7) and (8) in which the full-wave bridge rectifier consists; the necessary blocks for the regulation of the converter, consisting of the current measurement block (12), the main oscillator block (13) and the regulator block (19); and the blocks corresponding to the control system necessary to perform the dimming and compensation, consisting of the frequency divider block (14), the dimming level selector block (15) that allows the selection of the dimming level, VREF − DIM , the PWM pulse generator block for dimming (16), the dimming measurement block (18), the current selector block (21) that allows the selection of the current level, VREF − PK and the reference generator block of stream

(20) that generates the current reference in the form of a VREF voltage level by multiplying the dimming reference level and the desired peak current reference level. In this figure, in the auxiliary switch (11), G, D and S represent the control terminal, the active current input terminal and the active current output terminal, respectively, coinciding with the door, the drain and the source of a MOSFET transistor.

In Figure 1B, on the other hand, the circuit necessary to perform dimming with the peak current value defined in the design, integrated by the auxiliary switch (11) and its driver (17), is represented at the block level; the switched power converter (1), also considering the bus or output capacitor (9); the solid state lamp (10); the main connection of the converter to the power grid, consisting of phase (F) and neutral (N) for the alternating network, and positive (+) and negative (-) power for DC buses, consisting of the EMI filter consisting of the capacitors (2) and (4) and the coil (3), and the diodes (5), (6), (7) and (8) in which the full-wave bridge rectifier consists; the necessary blocks for the regulation of the converter, consisting of the current measurement block (12), the main oscillator block (13) and the regulator block (19); and the blocks corresponding to the control system necessary to perform the dimming and compensation, consisting of the frequency divider block (14), the dimming level selector block (15) that allows the selection of the dimming level, VREF − DIM , the PWM pulse generator block for dimming (16), the dimming measurement block (18) and the current reference generator block (20) that generates the current reference in the form of VREF voltage level by applying a gain to the desired dimming reference level. In this figure, in the auxiliary switch (11), G, D and S represent the control terminal, the active current input terminal and the active current output terminal, respectively, coinciding with the door, the drain and the source of a MOSFET transistor.

Fig. 2 shows the waveforms of the supply current of the solid state lamp (10), both in nominal operating mode and in dimming operation mode, where IPK corresponds to the peak level of the current operating in mode dimming, and IAVG corresponds to the average level of the pulsed current flowing through the solid state lamp. In case of operation in normal mode, that is, without dimming, the IPK eIAVG values are coincident.

Fig. 3 shows an example of (non-limiting) application of the dimming system associated with a Flyback converter operating in Discontinuous Driving Mode to power an LED load from the alternating energy network by performing power factor correction. A Flyback converter (1) with a transformer integrated by the primary (22) and secondary (23) coupled coils, the bus capacitor (9), the MOSFET transistor (24) and the secondary diode (25) is shown. The network connection through the EMI fi lter, consisting of the capacitors, is shown

(2) and (4) and the coil (3), and of the full wave rectifier comprising the diodes (5), (6), (7) and (8). The solid state lamp (10) is also shown, consisting of 60 LEDs and a MOSFET transistor as auxiliary switch (11) for dimming. The current measurement block (12), integrated by the current sensing resistor (26), is shown in series with the load, and the amplifier assembly consisting of the operational amplifier (27) and the resistors (28), (29). ) and (30). The main oscillator block (13), integrated in the control circuit LM3524 (31) used for topology control is shown, which has an internal oscillator that sets the operating frequency by means of the resistor (32) and the capacitor (33). ). In this application example, the dimming is performed at the same frequency as the switching of the MOSFET transistor (24) of the Flyback converter, so the frequency divider block (14) is shown as a 1: 1 block, being in the implementation nonexistent practice The dimming level selector block (15) is shown, implemented by a potentiometer connected between power and ground whose adjustable terminal provides a reference voltage, VREF − DIM. The PWM pulse generator block for dimming (16), consisting of a comparator, is shown. The driver (17) of the auxiliary switch, consisting of the resistors (34), (35) and (36), the optocoupler (37), the NPN transistor (38) and the PNP transistor (39) is shown. The dimming level measurement block (18), implemented by the operational amplifier (40), the resistors (41), (42) and (43) and the capacitor (44) is shown. The current reference generator block (20), consisting of an analog AD633 multiplier, is shown. The current selector block (21) is shown, implemented by means of a potentiometer connected between power and ground, whose adjustable terminal provides a reference voltage, VREF − PK. The regulator block (19), integrated by the integrated circuit (31), the resistance (45) and the capacitors (46) and (47) is shown. Finally, considered as part integrated in the Flyback converter (1), the steering driver of the MOSFET transistor (24) of the Flyback converter (1), consisting of resistors (48) and (49), the NPN transistor (50) is shown. ) and the PNP transistor (51).

Explanation of a preferred embodiment

In order to facilitate the understanding of the present invention, a practical example of application described in detail is set forth, without having to be understood as limiting the scope of the invention.

The application example is based on the use of a Flyback converter to power an LED lamp. Said converter was connected to the alternating energy network, so the power factor correction had to be made. This means that the input current wave, that is, the current wave that the ballast demands from the power grid, must meet the EN61000-3-2 standard for harmonic components. For this reason, the Flyback was designed to operate in Discontinuous Driving Mode (MCD) and, since the LEDs are current controlled devices, the control method used was that of averaged current, for its simplicity of design, using a PI regulator with an additional pole to ensure stable converter behavior without continuous error. Since the power factor correction converters have harmonic components at the output of twice the grid frequency, the output capacitor, fi lter or low frequency bus must be designed, thus presenting a slow dynamic in open loop. For this reason, the regulator must also have a bandwidth of less than twice the network frequency to avoid instabilities.

The LED lamp was first powered by direct current and then tested the dimming to a 10 to 1 dimming. This practical application is depicted in Fig. 3.

The Flyback converter (1), integrated by the MOSFET transistor (24), the secondary diode (25), the primary (22) and secondary (23) coupled coils and the bus capacitor (9), was fed from the network alternating, being connected to phase and neutral by means of an EMI filter consisting of two capacitors (2) and (4) and a coil (3), which acted as a high frequency interference suppressor complying with the specifications of EN55015 which refers to the radioelectric disturbance of lighting equipment and the like, or equivalent regulations in other countries. Next, a rectifier consisting of diodes (5), (6), (7) and (8) was arranged in order to obtain a continuous voltage equivalent to the unregulated rectified alternating voltage. The cathodes of the diodes (5) and (6) were connected to one of the primary coil terminals (22) of the Flyback, while the anode of the diodes (7) and

(8)

It was connected to the source of the N-channel MOSFET transistor (24) of the Flyback converter (1). On the other hand, the drain of the MOSFET transistor (24) was connected to the other terminal of the primary coil (22) of the Flyback. The output part of the Flyback converter was formed by the secondary coil (23). The terminal of this corresponding secondary coil with the terminal of the primary coil (22) connected to the cathode of the diodes (5) and (6) was in turn connected to the negative terminal of the output capacitor (9), whose positive terminal was connected to the cathode of the diode (25), connected to the other active terminal of the secondary coil (23) by means of the anode. Connected to the positive terminal of the output capacitor (9) and to the cathode of the diode (25) was the positive terminal of the LED lamp (10), that is, the anode of the first LED of the lamp. In turn, the negative terminal of the LED lamp (10), that is, the cathode of the last LED, was connected to the drain of the auxiliary switch (11) MOSFET dimming, whose source S was connected to a resistance terminal current sensor (26), represented as point A in Figure 3. The other terminal of the current sensor resistor (26) was connected to the negative terminal of the output capacitor (9) and to the secondary coil terminal ( 23) corresponding to the primary coil terminal (22) connected to the cathodes of the diodes (5) and (6). As for the control system considered internal to the Flyback converter (1), the PWM generator is included in the control circuit LM3524 (31) and the MOSFET transistor driver (24) of the Flyback converter (1) consists of resistors (48) and (49), the NPN transistor (50) and the PNP transistor (51). Said MOSFET transistor control driver (24) of the Flyback converter

(one)

It was configured as follows: the control pulse output terminal of the LM3524 regulator circuit (31) was connected to a driver consisting of resistors (48), (49), NPN transistor (50) and transistor PNP (51) mentioned above, so that the resistor (48) was connected via a terminal to the power supply, while the other terminal was connected to a resistor terminal (49). The other terminal of said resistor (49) was connected to the common ground of the control circuit. The collector of the NPN transistor (50) was also connected to the supply, while its base and the base of the PNP transistor (514) were arranged connected to the intermediate terminal of the resistive divider formed by the resistors (48) and (49) and to the control pulse output terminal of the control circuit LM3524 (31). The transmitter of the NPN transistor (50) was connected to the transmitter of the PNP transistor (51), whose collector was in turn connected to the common ground of the control circuit. The emitter of both transistors was arranged connected to the door of the MOSFET transistor (24) of the Flyback converter (1), indicated in Fig. 3 as point G.

With respect to the control circuit, a current measurement block (12) consisting of a conditioning and amplification system of the signal measured in the sensor resistor (26) integrated by the operational amplifier (27) in non-inverting configuration was arranged and the resistors (28), (29) and (30), of which the resistance (28) is used to reduce the continuous deviation error. This conditioning circuit was connected to the terminal shared by the source of the auxiliary switch (11) MOSFET dimming channel N and the current sensing resistor (26), that is, point A, through the resistor (28). In turn, the output of the amplification circuit of the signal measured in the sensor resistor (26) was connected to the inverting input of the comparator of the control circuit LM3524 (31). Said control circuit LM3524 (31) was fed between the control supply and ground. The main oscillator block (13) consists of the internal oscillator of the control circuit LM3524 (31), the resistor (32) and the capacitor (3), connected between ground and its respective input of the control circuit LM3524 (31), and provides a high frequency triangular signal. For reasons of simplicity, the same signal was used to perform the dimming, thereby dispensing with the frequency divider block (14) in the prototype, although to improve understanding and maintain consistency with numbering, it is shown in the figure as a 1: 1 gain block. To perform the dimming, said high frequency signal was extracted from the capacitor terminal (33) that was connected to the control circuit LM3524 (31), called point A, in Figure 3. Consequently, the switching frequency and the Dimming in this application example were identical. The design of the regulator block (19) corresponded to a PI structure with an additional pole to ensure an arrangement of poles and zeros that allowed the maximum possible bandwidth (close to twice the grid frequency), while keep the phase margin at high values. Said regulator block (19) was formed by the resistor (45) and the capacitors (46) and (47), the resistor (45) and the capacitor (46) being connected in series and in parallel, in parallel with the capacitor (47). Said parallel impedance was connected between the corresponding terminal of the control circuit LM3524

(31)

and dough The PWM pulse generator block for dimming (16) was in turn formed by an LM393 comparator that compared the high frequency triangular signal extracted from point A, connected to the inverting input

of the comparator LM393, with a continuous reference level for dimming, VREF − DIM, generated by the dimming level selector block (15), consisting of a potentiometer, one of whose terminals was connected to power, the other terminal a ground, and the intermediate terminal was connected to the non-inverting input of comparator LM393 in order to generate the control pulse train of the auxiliary switch (11) MOSFET dimming, GDIM. Connected to the output of comparator LM393 was the driver (17) of the auxiliary switch (11) MOSFET dimming, consisting of a current limiting resistor (34). One of its terminals was connected to the output of comparator LM393, while the other terminal was connected to the anode of the internal LED of the optocoupler (37) to isolate the control of the dimming MOSFET auxiliary switch (11). The cathode of the internal LED diode of the optocoupler (37) was connected to the common ground of the control circuit.

On the output side, the emitter of the internal phototransistor of the optocoupler (37) was arranged connected to an isolated ground, connected in turn with the source of the auxiliary switch (11) MOSFET of dimming, S, to isolate the steering pulses of said component and thus avoid unwanted interference and current recirculation through the current sensing resistor (26). In turn, the collector of said phototransistor was connected to the midpoint of a resistive divider formed by the resistors (35) and (36) to correctly polarize the NPN (38) and PNP (39) transistors, all these components constituting the driver (17) of the auxiliary switch control (11) MOSFET dimming. The remaining components of the driver (17) were configured as follows: the bases of both transistors (38) and (39) were connected to each other at the midpoint of the resistive divider formed by the resistors (35) and (36) and to the collector of the internal phototransistor of the optocoupler (37). The NPN transistor collector (38) was connected to the positive terminal of an independent power supply and its emitter was connected to the PNP transistor emitter (39), whose collector was connected to the independent ground. The emitters of both bipolar transistors were connected to the door of the dimming MOSFET auxiliary switch (11), point indicated as GD in Fig. 3.

As for the variable reference signal, VREF, this was generated by the current reference generator block (20) as follows: the output of the comparator LM393 that configures the PWM pulse generator block for dimming (16) was also connected to the dimming measuring block (18), consisting of a fi lter in low-pass configuration whose function was to extract the average value of the steering pulse train from the auxiliary switch (11) MOSFET dimming, GDIM. Said dimming measuring block (18) was composed of the operational amplifier (40), the resistors (41), (42) and (43) and the capacitor (44). The output of the dimming level measurement block (18), DIM signal, was arranged connected to one of the input terminals of the current reference generator block (20), integrated by an analog AD633 multiplier, as shown in Fig. 3, while the other input terminal of said analog multiplier AD633 was connected to the intermediate terminal of the potentiometer that constituted the current selector block (21), one of whose terminals was connected to power and the other to ground. This potentiometer was responsible for selecting the peak current level by means of the voltage level at its intermediate terminal, VREF − PK. The output terminal of the analog multiplier AD633 that constituted the current reference generator block (20) was connected to the non-inverting input of the internal comparator of the control circuit LM3524 (31) used.

Claims (62)

1. Serial PWM dimming system for solid state lamps, comprising:

-

a switched power converter (1), and an input EMI filter which in turn comprises two capacitors (2) and (4), a coil (3), four rectifier diodes (5), (6), (7 ) and (8), and a bus capacitor

or exit (9);

-

a solid state lamp (10);

-

an auxiliary switch (11) arranged in series with the solid state lamp (10) by which the dimming function is performed;

-

a current measurement block (12) for measuring the current flowing through the solid state lamp (10);

-

a main oscillator block (13) that generates the high frequency signal that is used to control the transistor or transistors of the switched power converter (1);

-

a frequency divider block (14) that receives the high frequency signal generated by the main oscillator block (13) and divides the frequency of said signal to generate a new signal which, after applying it to the PWM pulse generator block for dimming (16 ), is used to perform the dimming of the solid state lamp (10);

-

a dimming level selector block (15) that allows selecting the dimming level;

-

a PWM pulse generator block for dimming (16) that generates the dimming signal from the signals coming from the dimming level selector block (15) and the main oscillator block (13);

-

a driver (17) of the auxiliary switch (11) that transmits to the auxiliary switch (11) the dimming signal generated by the PWM pulse generator block for dimming (16);

-

a dimming measurement block (18) that measures the dimming level selected by the user;

-

a current reference generator block (20) that generates the current reference for the regulation loop of the closed-chain luminaire from the signal from the dimming measurement block (18);

-

a regulator block (19) that generates a control signal from the error signal obtained by subtracting the signal from the current measurement block (12) from the signal from the current reference generator block (20);

characterized in that the switching of the auxiliary switch (11), and consequently, the PWM dimming, is performed at high frequency and that the switched power converter (1) is slow dynamic.

2.

A serial PWM dimming system according to claim 1, characterized in that the switched power converter (1) is a single stage AC / DC converter with a bandwidth less than twice the grid frequency, or an AC converter Integrated DC / DC whose bandwidth is at least two decades lower than the switching frequency, or a two-stage AC / DC converter whose bandwidth is at least two decades lower than the switching frequency, or a DC / DC converter whose bandwidth is at least two decades lower than the switching frequency.

3.

A serial PWM dimming system according to claim 1, characterized in that the switched power converter (1) operates in voltage mode or in current mode, connected to the alternating power network or continuous power supply abuses, in any of the following modes Driving: Continuous Driving Mode, Discontinuous Driving Mode or Border Driving Mode, at fixed or variable frequency.

Four.

A serial PWM dimming system according to claim 3, characterized in that the switched power converter (1) operates in current mode, and incorporates a medium current control, with a single regulation loop.

5.

A serial PWM dimming system according to claim 4, characterized in that the control signal from the regulator block (19) is used to generate the steering pulses of the main transistor of the switched power converter (1), thus implementing a closed loop control system in medium current mode.

6.

A serial PWM dimming system according to claim 3, characterized in that the switched power converter (1) operates in current mode and incorporates a peak current control with an external regulation loop and an internal regulation loop.

7.

A serial PWM dimming system according to claim 6, characterized in that the control signal from the regulator block (19) is used to generate a control signal that is complemented by the reading of the peak current of the main transistor of the converter switched power (1), thus implementing a peak current control scheme, where the regulator block (19) represents the regulator of the external control loop, considering the internal control loop as internal to the switched power converter (1).

8.

A series PWM dimming system according to claim 1, characterized in that the solid state lamp (10) is at least one LED, an OLED or a PLED.

9.

A series PWM dimming system according to claim 8, characterized in that the solid state lamp (10) comprises means of heat dissipation by natural or forced convection.

10.

A series PWM dimming system according to claim 1, characterized in that the current measurement block (12) performs the filtering of the high frequency components of the output current that is fed back to the regulator block (19).

eleven.

A serial PWM dimming system according to claim 10, characterized in that it executes serial dimming at a frequency of the same order of magnitude as the switching frequency of the switched power converter (1), so that the regulating block (19) acts on the average value of the pulsed current modifiable by means of the dimming duty cycle.

12. A serial PWM dimming system according to claim 1, wherein the current measurement block (12) Firmly transmits the output current to the regulator block.

13.

A serial PWM dimming system according to claim 12, characterized in that it executes serial dimming at a frequency of the same order of magnitude as the switching frequency of the switched power converter (1), so that the pulsing current is interpreted as disturbances. high frequency and fi ltered by the closed chain regulation loop.

14.

A series PWM dimming system according to claim 1, characterized in that the frequency divider block (14) divides by the unit for dimming the solid state lamp (10) at the same frequency as the switching frequency of the transistor or main transistors of the switched power converter (1),

or divide by values greater than the unit to perform the dimming of the solid state lamp (10) at frequencies lower than the switching frequency of the main transistor or transistors of the switched power converter (1).

fifteen.

A serial PWM dimming system according to claim 14, characterized in that the frequency divider block (14) is implemented with analog, digital components and / or by program function blocks or software programs.

16.

A serial PWM dimming system according to claim 14, further comprising a current selector block (21) by which the user selects the level of direct current in normal operation mode, and the peak level in dimming operation mode .

17.

A serial PWM dimming system according to claim 16, characterized in that the dimming level selector block (15) is implemented with analog, digital components and / or by program function blocks or software programs.

18.

A serial PWM dimming system according to claim 16, characterized in that the user accesses the dimming level selector block (15) manually or by means of commands issued through communications networks.

19.

A series PWM dimming system according to claim 16, characterized in that it feeds the solid state lamp by means of a square current wave with modifiable pulse width, whose minimum value is null and whose peak value is selectable by the user.

twenty.

A series PWM dimming system according to claim 16, characterized in that the current reference generator block (20) generates the current reference for the closed chain regulation loop from the signals coming from the dimming measurement block ( 18) and the current selector block (21).

twenty-one.

A serial PWM dimming system according to claim 14, characterized in that the switched power converter (1) operates in voltage mode or in current mode, connected to the alternating power network or continuous power supply busses, in any of the following modes Driving: Continuous Driving Mode, Discontinuous Driving Mode or Border Driving Mode, at fixed or variable frequency.

22

A serial PWM dimming system according to claim 21, characterized in that the switched power converter (1) operates in current mode and incorporates a medium current control, with a single regulation loop.

2. 3.

A serial PWM dimming system according to claim 22, characterized in that the control signal from the regulator block (19) is used to generate the steering pulses of the main transistor of the switched power converter (1), thus implementing a closed loop control system in medium current mode.

24.

A series PWM dimming system according to claim 21, characterized in that the switched power converter (1) operates in current mode and incorporates a peak current control with an external regulation loop and an internal regulation loop.

25.

A serial PWM dimming system according to claim 24, characterized in that the control signal from the regulator block (19) is used to generate a control signal that is complemented by the reading of the peak current of the main transistor of the converter switched power (1), thus implementing a peak current control scheme, where the regulator block (19) represents the regulator of the external control loop, considering the internal control loop as internal to the switched power converter (1).

26.

A series PWM dimming system according to claim 14, characterized in that the solid state lamp (10) is at least one LED, an OLED or a PLED.

27.

A series PWM dimming system according to claim 26, characterized in that the solid state lamp (10) comprises means of heat dissipation by natural or forced convection.

28.

A series PWM dimming system according to claim 14, characterized in that the current measurement block (12) performs the filtering of the high frequency components of the output current that is fed back to the regulator block (19).

29.

A serial PWM dimming system according to claim 28 characterized in that it executes serial dimming at a frequency of the same order of magnitude as the switching frequency of the switched power converter (1), so that the regulating block (19) acts on The average value of the pulsed current can be modified using the dimming duty cycle.

30. A serial PWM dimming system according to claim 14 wherein the current measurement block (12) Firmly transmits the output current to the regulator block.

31.

A serial PWM dimming system according to claim 30, characterized in that it executes serial dimming at a frequency of the same order of magnitude as the switching frequency of the switched power converter (1), so that the pulsing current is interpreted as disturbances high frequency and fi ltered by the closed chain regulation loop.

32

A serial PWM dimming system according to claim 1, further comprising a current selector block (21) by means of which the user selects the level of direct current in normal operating mode and the peak level in dimming operating mode.

33.

A serial PWM dimming system according to claim 32, characterized in that the dimming level selector block (15) is implemented with analog, digital components and / or by program function blocks or software programs.

3. 4.

A serial PWM dimming system according to claim 32, characterized in that the user accesses the dimming level selector block (15) manually or by means of commands issued through communications networks.

35

A series PWM dimming system according to claim 32, characterized in that it feeds the solid state lamp by means of a square current wave with modifiable pulse width, whose minimum value is null and whose peak value is selectable by the user.

36.

A series PWM dimming system according to claim 32, characterized in that the current reference generator block (20) generates the current reference for the closed chain regulation loop from the signals coming from the dimming measurement block ( 18) and the current selector block (21).

37.

A serial PWM dimming system according to claim 32, characterized in that the switched power converter (1) operates in voltage mode or in current mode, connected to the alternating power network or continuous power supply abuses, in any of the following modes Driving: Continuous Driving Mode, Discontinuous Driving Mode or Border Driving Mode, at fixed or variable frequency.

38.

A serial PWM dimming system according to claim 37, characterized in that the switched power converter (1) operates in current mode and incorporates a medium current control, with a single regulation loop.

39.

A serial PWM dimming system according to claim 38, characterized in that the control signal from the regulator block (19) is used to generate the steering pulses of the main transistor of the switched power converter (1), thus implementing a closed loop control system in medium current mode.

40

A serial PWM dimming system according to claim 37, characterized in that the switched power converter (1) operates in current mode and incorporates a peak current control with an external regulation loop and an internal regulation loop.

41.

A serial PWM dimming system according to claim 40, characterized in that the control signal from the regulator block (19) is used to generate a control signal that is complemented by the reading of the peak current of the main transistor of the converter switched power (1), thus implementing a peak current control scheme, where the regulator block (19) represents the regulator of the external control loop, considering the internal control loop as internal to the switched power converter (1).

42

A series PWM dimming system according to claim 32, characterized in that the solid state lamp (10) is at least one LED, an OLED or a PLED.

43

A series PWM dimming system according to claim 42, characterized in that the solid state lamp (10) comprises means of heat dissipation by natural or forced convection.

44.

A serial PWM dimming system according to claim 32 characterized in that the current measurement block (12) performs the filtering of the high frequency components of the output current that is fed back to the regulator block (19).

Four. Five.

A serial PWM dimming system according to claim 44, characterized in that it executes serial dimming at a frequency of the same order of magnitude as the switching frequency of the switched power converter (1), so that the regulating block (19) acts on the average value of the pulsed current modifiable by means of the dimming duty cycle.

46. A serial PWM dimming system according to claim 32 wherein the current measurement block (12) Firmly transmits the output current to the regulator block.

47

A serial PWM dimming system according to claim 46, characterized in that it executes serial dimming at a frequency of the same order of magnitude as the switching frequency of the switched power converter (1), so that the pulsing current is interpreted as disturbances high frequency and fi ltered by the closed chain regulation loop.

48.

A serial PWM dimming system according to claim 1, 14 or 32, characterized in that the auxiliary switch (11) is a bipolar transistor, MOSFET or IGBT, with its active input terminal connected to the cathode of the last diode of the status lamp solid (10), with its active output terminal connected to the input terminal of the current measurement block (12), and whose control terminal receives, through a driver (17), the dimming signal generated in the block PWM pulse generator for dimming (16).

49.

A serial PWM dimming system according to claim 1, 14 or 32, characterized in that the current measurement block (12) is implemented with analog, digital components and / or by program function blocks or software programs.

fifty.

A serial PWM dimming system according to claim 1, 14 or 32, characterized in that the main oscillator block (13) is implemented with analog, digital components and / or by program function blocks or software programs.

51.

A serial PWM dimming system according to claim 1, 14 or 32, characterized in that the PWM pulse generator block for dimming (16) is implemented with analog, digital components and / or through program functional blocks or software programs.

52

A serial PWM dimming system according to claim 1, 14 or 32, characterized in that the auxiliary switch control driver (17) consists of discrete components or specific integrated circuits.

53.

A serial PWM dimming system according to claim 1, 14 or 32, characterized in that the dimming measuring block (18) is implemented with analog, digital components and / or by program function blocks or software programs.

54

A serial PWM dimming system according to claim 1, 14 or 32, wherein the current selector block (21) is implemented with analog, digital components and / or by program function blocks or software programs.

55.

A serial PWM dimming system according to claim 1, 14 or 32, characterized in that the user accesses the current selector block (21) manually or by means of commands issued through communications networks.

56.

A serial PWM dimming system according to claim 1, 14 or 32, characterized in that the current reference generator block (20) is implemented with analog components, specific integrated circuits, digital components and / or by program or program functional blocks of software.

57.

A serial PWM dimming system according to claim 1, 14 or 32, characterized in that the regulator block (19) that implements the closed chain control loop is analog.

58.

A serial PWM dimming system according to claim 1, 14 or 32, characterized in that the regulator block (19) that implements the closed chain control loop is digital.

59.

A series PWM dimming system according to claim 1, 14 or 32, characterized in that the solid state lamp (10) is fed by a square current wave with modifiable pulse width, whose minimum value is null and whose peak value It is a system design parameter not selectable by the user.

60

A series PWM dimming system according to claim 1, 14 or 32, characterized in that the average value of the current wave that feeds the solid state lamp (10) is proportional to the time in which its value is not zero in relation to with the dimming switching period.

61.

A serial PWM dimming system according to claim 1, 14 or 32, characterized in that the peak value of the output current is kept constant regardless of the dimming duty cycle employed by compensating the peak value of the output current by modifying , by means of the current reference generator block (20), the current reference of the switched power converter (1).

SPANISH OFFICE OF THE PATENTS AND BRAND Application no .: 201000223 SPAIN Date of submission of the application: 19.02.2010 Priority Date: REPORT ON THE STATE OF THE TECHNIQUE 51 Int. Cl.: H05B33 / 08 (2006.01) H03K7 / 08 (2006.01) RELEVANT DOCUMENTS

Category

Documents cited Claims Affected

TO

XP 031442735 A "A Universal-Input Single-Stage High-Power-Factor Power Supply for HB-LEDs Based on Integrated Buck-Flyback Converter" (GACIO D. et al). 02.15.2009. Applied Power Electronics Conference and Exposition, 2009. APEC 2009. Twenty-Fourth Annual IEEE, ISBN 978-1-4244-2811-3; whole document. 1-61

TO

XP 011202576 A 01.03.2008, "A Single-Stage High-Power-Factor Electronic Ballast Based on Integrated Buck Flyback Converter to Supply Metal Halide Lamps" (DALLA COSTA M A. et al). 01.03.2008. IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, ISSN 0278-0046; whole document. 1-61

TO

XP 011202513 A "Integrated Buck-Flyback Converter as a High-Power-Factor Off-Line Power Supply" (ALONSO J M. et al). 01.03.2008. EEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, ISSN 0278-0046; whole document. 1-61

TO

EN 2347829 T3 (TRIDONICATCO GMBH & CO KG) 04.11.2010, the whole document. 1-61

Category of the documents cited X: of particular relevance Y: of particular relevance combined with other / s of the same category A: reflects the state of the art O: refers to unwritten disclosure P: published between the priority date and the date of priority submission of the application E: previous document, but published after the date of submission of the application

This report has been prepared • for all claims • for claims no:

Date of realization of the report 16.05.2011

Examiner J. Calvo Herrando Page 1/4

REPORT OF THE STATE OF THE TECHNIQUE Application number: 201000223 Minimum documentation sought (classification system followed by classification symbols) H05B, H03K Electronic databases consulted during the search (name of the database and, if possible, terms of search used) INVENES, EPODOC, WPI State of the Art Report Page 2/4  WRITTEN OPINION Application number: 201000223 Date of Completion of Written Opinion: 05/16/2011 Statement

Novelty (Art. 6.1 LP 11/1986)

Claims Claims 1-61 IF NOT

Inventive activity (Art. 8.1 LP11 / 1986)

Claims Claims 1-61 IF NOT

The application is considered to comply with the industrial application requirement. This requirement was evaluated during the formal and technical examination phase of the application (Article 31.2 Law 11/1986).  Opinion Base.- This opinion has been made on the basis of the patent application as published. State of the Art Report Page 3/4  WRITTEN OPINION Application number: 201000223 1. Documents considered.- The documents belonging to the state of the art taken into consideration for the realization of this opinion are listed below.

Document

Publication or Identification Number publication date

D01

XP 031442735 A 02.15.2009

D02

XP 011202576 A 01.03.2008

D03

XP 011202513 A 01.03.2008

D04

ES 2347829 T3 (TRIDONICATCO GMBH & CO KG) 04.11.2010

The claimed invention features a high frequency serial PWM dimming system for solid state lamps. Document D01 is considered to be the closest prior art document to the object claimed. 2. Statement motivated according to articles 29.6 and 29.7 of the Regulations for the execution of Law 11/1986, of March 20, on Patents on novelty and inventive activity; quotes and explanations in support of this statement  R1 independent claim Document D01 discloses a high frequency PWM dimming system for solid state lamps that has a switched power converter, an EMI filter, at least one solid state lamp, a current measurement block, a main oscillator, a PWM signal generator block and a regulator block that generates a control signal. In addition, document D01 describes several ways of performing the PWM dimming, among them the "serial dimming" is described where another switching element is placed in series with the load to perform the regulation. However, the implementation of the "dimming series" describing the claimed invention is not considered obvious to one skilled in the art; since said system has a PWM pulse generator block for dimming, a dimming level selector block, a driver for the serial switching element with the load, a dimming measurement block and a reference generator block of current from the measurement of the dimming performed. Consequently, the invention is new and is considered to imply inventive activity and has industrial application.  Dependent claims R2-R61 Claims R2-R61 are dependent on claim R1 and like it, they also meet the requirements of novelty and inventive activity, since they add additional technical characteristics of more limited scope, without modifying the essential nature of the invention. State of the Art Report Page 4/4