EP3967110A1 - Convertisseur à del - Google Patents

Convertisseur à del

Info

Publication number
EP3967110A1
EP3967110A1 EP20734235.3A EP20734235A EP3967110A1 EP 3967110 A1 EP3967110 A1 EP 3967110A1 EP 20734235 A EP20734235 A EP 20734235A EP 3967110 A1 EP3967110 A1 EP 3967110A1
Authority
EP
European Patent Office
Prior art keywords
led
converter
current
feedback
stage
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP20734235.3A
Other languages
German (de)
English (en)
Inventor
Ludwig Erasmus DE CLERCQ
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tridonic GmbH and Co KG
Original Assignee
Tridonic GmbH and Co KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tridonic GmbH and Co KG filed Critical Tridonic GmbH and Co KG
Publication of EP3967110A1 publication Critical patent/EP3967110A1/fr
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • H05B45/3725—Switched mode power supply [SMPS]
    • H05B45/382—Switched mode power supply [SMPS] with galvanic isolation between input and output
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • H05B45/3725—Switched mode power supply [SMPS]
    • H05B45/39—Circuits containing inverter bridges

Definitions

  • the present invention relates to a converter for the operation of at least one light source, in particular a converter circuit for the operation of a LED load having at least one LED.
  • a switched resonant circuit such as an isolated LLC converter can be included in driver circuits for operating LEDs which are basically known from the prior art.
  • driver circuits are powered by an electric supply source and the (isolated) resonant, e.g. LLC, LCC etc., converter is responsible for transferring power over a galvanic barrier from a primary side to a secondary side of the isolated resonant converter.
  • LCC converter is to be understood as any resonant converter and to include at least a LCC converter.
  • the LED load is driven off terminals at the secondary side of the LLC.
  • a control circuit for controlling the LED current can be provided, wherein an actual value of the LED current can be measured on the secondary side of the galvanic isolation barrier.
  • this actual value measurement can be fed- back, crossing the isolation barrier, to a primary-side control circuit to control one or more switches, especially the switching frequency and/or duty cycle of the LLC accordingly .
  • the LED current is determined by putting into the relation the following physical entities:
  • the invention relates to a LED converter, comprising an isolated switched resonant stage supplying terminals for driving an LED load, wherein an LED current is feedback-controlled based on feedback-control signals.
  • the signal indicating the LED current is sensed at a primary side stage.
  • the control unit controls at least one switch, preferably to alternatively clicked switches connected in series, of the switched resonant stage on the basis of the feedback-control signals.
  • Said feedback-control signals comprise a signal representing the voltage across the LED load V LED , a signal indicating a DC supply voltage ("bus voltage") of the primary side, and a signal sensed at the primary side and representing the current flowing on the primary side of the isolation stage of isolated switched resonant stage.
  • the at least one signal representing the current on the primary side of the isolation stage of isolated switched resonant stage may comprise two differentially sensed signals.
  • the at least one signal representing the current on the primary side of the isolation stage of isolated switched resonant stage may be sensed by a differential current sensing block in series to a capacitor stabilizing a DC supply voltage of the converter, or in series to said at least one switch.
  • the differential current sensing block is also designated as a "tapping unit”.
  • the control unit may control the at least one switch by frequency modulation and / or duty cycle control.
  • the LED converter is an isolated half-bridge LLC converter.
  • the LLC converter comprises on the primary side a tapping unit, wherein the tapping unit comprises a sensing resistor R s , a capacitor C f in parallel to R s , two resistors R f i , R f2 , wherein R f i is in parallel to R f2 and wherein the value of R f i is equal to the value of R f2 , and wherein the capacitor C f is connected between R f i and R f2 , and wherein the resistor R s is connected between R f l and R f2 .
  • a first current value i snsp is tapped off between the resistor R fi and the capacitor C f
  • a second current value i snsi is tapped off between the resistor R f2 and the capacitor C f .
  • the controller is configured to determine the following value based on a differential sensing of a current flowing into the converter :
  • the LED converter further comprises a rectifier and the controller is further configured to determine the current flowing through the LED i LED on the basis of the following equation:
  • V D is a voltage drop of a diode of the rectifier. Losses are considered depending on the selected implementation/topologies .
  • the controller is further configured to estimate a power (loss) of the rectifier P re ct on the basis of the following equation:
  • the LLC converter further comprises a capacitor on the secondary side.
  • the LLC converter further comprises an auxiliary winding coupled to a primary winding of a transformer of the LLC converter.
  • the invention relates to a LED luminaire comprising an LED converter according to the first aspect or any one of the implementation forms thereof.
  • the invention relates to a method for an LED converter, comprising the following steps: supplying terminals for driving an LED load, feedback controlling an LED current i LED based only on feedback-control signals and controlling at least one switch of a switched resonant stage on the basis of the feedback-control signals.
  • Said feedback-control signals comprise a signal representing the voltage across the LED load V LED , a signal indicating a DC supply voltage of the primary side V B u s/ and a signal representing the current flowing into the LED converter i PFC .
  • Fig. 1 shows a schematic diagram of an LED converter according to an embodiment of the invention
  • Fig . 2 shows a further schematic diagram of an LED converter according to an embodiment of the invention
  • Fig. 2a shows an alternative embodiment to Fig.2
  • Fig. 3 shows a schematic diagram of a method for an LED converter according to an embodiment of the invention.
  • Fig. 4 shows a schematic diagram of an LED converter including a PFC according to an embodiment of the invention .
  • LED luminaire shall mean a luminaire with a light source comprising one or more LEDs. LEDs are well-known in the art, and therefore, will only briefly be discussed to provide a complete description of the invention.
  • CMOS complementary metal-oxide semiconductor technology
  • the aspects of the present invention may be implemented with other manufacturing processes for making optical as well as electrical devices.
  • the LED converter 100 comprises an isolated switched resonant stage supplying terminals for driving an LED load 106, wherein an LED current i LED is feedback-controlled based only on feedback-control signals from a primary side stage 102.
  • the LED converter 100 comprises a control unit 108 controlling at least one switch Si, S2 of the switched resonant stage on the basis of the feedback-control signals.
  • the feedback-control signals comprise a signal representing the voltage across the LED load V LED , a signal indicating a DC supply voltage of the primary side V BUS , and a signal representing the current flowing into the LED converter i PFC .
  • PFC indicates that according to an example the current flowing into the LED converter e.g. LLC may be supplied by an actively switched power factor correction circuit (PFC) whereby this PFC provides a stabilized DC voltage (V B u s) ⁇
  • PFC is shown in Figure 4 explained later on.
  • Fig. 2 shows a further embodiment of an LED converter 200 according to the invention.
  • the LED converter is an LLC converter 200.
  • the LLC converter 200 comprises a primary side 102 and a secondary side 104.
  • the primary side 102 can be supplied by a DC voltage V B u s , for instance by a PFC as shown in Fig. 4.
  • the sensing of the DC voltage V B u s may be used for PFC control, i.e. the control of a switch of the PFC, as well as for the control (frequency, duty cycle, deadtime between the on time of two switches connected in series) of at least one switch (SI, S2), preferably two switches connected in series, of the switched resonant stage by the control unit 108.
  • the DC voltage VBus isupplied to a capacitor CPFC the voltage of which is the DC supply voltage of an isolated switches resonant converter stage, which in the present example comprises a half-bridge converter with two switches SI, S2 connected in series and controlled by the control unit.
  • the midpoint voltage of the half-bridge converter SI, S2 is fed to a series resonance circuitry LI, C2.
  • the inductor LI is the primary winding of a transformer T which comprises a secondary winding L2.
  • the voltage across the secondary winding L2 is supplied to a rectifier 204 feeding a capacitor C3.
  • the DC voltage across the capacitor C3 is the supply voltage of the LED load 106.
  • the switches SI, S2 are controlled by corresponding control signals from the control unit 108.
  • the primary side 102 can comprise a tapping unit 200a, also called “differential sensing block", wherein the tapping unit 200a can comprise a sensing resistor R s , a capacitor C f in parallel to R s , two resistors R fi , R f 2.
  • the resistor R fi is in parallel to the resistor R f 2 and the resistance value of R fi is equal to the resistance value of R f 2.
  • the capacitor C f can be connected between R fi and R f 2
  • the resistor R s can be connected between R fi and R f 2.
  • the tapping unit 200a can be configured to tap off a first voltage value used to detect the current i S ns P between the resistor R fi and the capacitor C f , and a second voltage value used to detect the current i snsi between the resistor R f2 and the capacitor C f .
  • this is an example of a differential sensing of the current flow through the resistor Rs .
  • the resistor Rs senses the current flowing through the capacitor Cpfc. This is one example of sensing a current flow on the primary side of the isolation stage of isolated switched resonant stage, and which is used to calculate (see further below) a secondary side current, especially the LED current to be feed-back controlled by the control unit.
  • the controller 108 can be configured to determine the following value:
  • ⁇ sensing> i snsp - isns 1 wherein this value ⁇ sensing> corresponds to a voltage difference indicating the current i PfC flowing through R s .
  • the controller 108 can be configured to perform the following steps:
  • the controller 108 can be configured to perform the following steps:
  • the power P re ct of the rectifier 204 can be expressed as :
  • V D is a diode voltage drop and the scaling factor 4 reflect how many diodes are used in the rectifier 204, namely, in this embodiment, 4.
  • the load power can be expressed as:
  • the LLC converter 200 can even comprise a smoothing circuit on the secondary side 104, the capacitor C 3 in the embodiment shown in Fig. 2, wherein the smoothing circuit is configured to smooth the ripple at the output of the LLC converter 200 in order to obtain a smoothed voltage.
  • the LLC converter 200 can further comprise an auxiliary winding coupled to a primary winding Li of a transformer T of the LLC converter 200.
  • the LED voltage V LED is indirectly measured, indirectly meaning by an electric parameter tapped off the primary side 102 of the isolated LLC converter 200.
  • this is done using the auxiliary winding coupled to the primary winding LI of the transformer T.
  • Fig. 2a shows an alternative embodiment to Figure 2.
  • the relevant difference to Figure 2 resides in the fact that the tapping unit 200a is connected as a shunt in series to the lower potential half-bridge switch S2.
  • the tapping unit 200a acts as a current sensing block.
  • the half-bridge comprising the switches SI, S2 of the resonant converter is clocked with approx. 50% duty cycle (with some dead time)
  • the current fed into the resonant converter flows during the switch on-times of the resp. switch through that switch.
  • the current flows during the first half through the first switch SI (upper) and second half back through the second (low side) switch S2 - thus sensing can be done at this sensing point in series to the switch S2.
  • the tapping unit (current sensing block) 200a of this embodiment is also designed for a differential current sensing. It comprises a shunt resistor Rs, two differential resistors Rfl, Rf2 connected by a capacitor Cf. The voltage across the capacitor Cf is lead to two output terminals Isnsl, Isns2 connected to corresponding input terminals of the control unit, such that the control unit can process these two differential sensing in order to obtain a value representing the current flowing into the converter.
  • Fig. 3 shows a schematic diagram of a method 300 for an LED converter 100.
  • the method 300 comprises the steps of: supplying 302 terminals for driving an LED load 106, feedback-controlling 304 an LED current i LED based only on feedback-control signals from a primary side stage 102; controlling 306 at least one switch Si, S2 of a switched resonant stage (preferably the switching frequency and/or the duty cycle) on the basis of the feedback-control signals .
  • the feedback-control signals comprise: a) a signal representing the voltage across the LED load VLED b) a signal indicating a DC supply voltage of the primary side VB US ; and c) a signal representing the current flowing into the LED converter i PFC .
  • Fig. 4 shows schematic representation of an alternative embodiment of an LED converter 500 according to the invention.
  • the driver 500 can comprise a converter 200, for instance a half bridge LLC HB-LLC or LCC converter.
  • the converter 200 can be any one of the converters 100 of the Figs. 1 to 2a.
  • the converter 200 may comprise a primary side stage 102 and a secondary side 104.
  • the primary side stage 102 comprises a primary winding LI of a transformer T and the secondary side 104 comprises a secondary winding L2 of the transformer T, whereby the secondary side 104 is magnetically coupled to the primary side stage 102 via the transformer T.
  • the driver 500 can further comprise an electromagnetic interference (EMI) filter 501 that forwards an input voltage to an activelely switched PFC 503, in particular a boost PFC circuit.
  • EMI electromagnetic interference
  • the PFC 503 can in turn supply the primary side 102 of the converter 200 with a DC voltage V B u s ⁇
  • the driver 500 can further comprise a control unit implemetee e.g. as an ASIC 508.
  • the ASIC 508 can correspond to the control unit 108 or to a component of the control unit 108 from Figs. 1 to 2a.
  • the ASIC 508 can be configured to perform a feedback control of the secondary side voltage of the converter 504 and/or the PFC circuitry 503 by means of a control of the switches of the half bridge of the half bridge LLC or LCC .
  • the control unit (ASIC) 508 may be supplied by a secondary side feedback signal, preferably form a secondary side rectification stage, via an isolation stage (transformer) 505b. However, the control unit is not supplied with a secondary side LED current sensing signal.
  • the driver 500 can further comprise a low voltage power supply 507 which can be configured to supply integrated circuits of the driver 500, e.g. the ASIC 508, with a low DC supply voltage .
  • the driver 500 can further comprise a microcontroller 509, which can be configured to control the ASIC 508 and bidirectionally communicate with the ASIC 508.
  • the microcontroller 509 can send signals to the ASIC 508 in order to control the ASIC 508, e.g. adjust a lamp brightness.
  • the microcontroller 509 can receive signals from the ASIC 508, e.g. lamp fault detection.
  • the driver 500 comprises a rectification and sensing circuit 506, which is isolated from the other components of the driver 500 and coupled to the converter 504 and ASIC 508 via two transformers 505a, 505b.
  • the driver 500 can further comprise a dimming interface 513, e.g. DALI interface, which is isolated e.g. via an optocoupler 511a, 511b from the microcontroller 509. Signals can be exchanged between the dimming interface 513 and the microcontroller 509 via two optocouplers 511a, 511b.
  • a dimming interface 513 e.g. DALI interface
  • an optocoupler 511a, 511b from the microcontroller 509. Signals can be exchanged between the dimming interface 513 and the microcontroller 509 via two optocouplers 511a, 511b.

Landscapes

  • Circuit Arrangement For Electric Light Sources In General (AREA)
  • Dc-Dc Converters (AREA)

Abstract

La présente invention porte sur un convertisseur à DEL, comprenant : un étage résonnant à commutation isolé (LLC) qui alimente des bornes pour commander une charge de DEL (106), un courant iDEL de DEL étant commandé par rétroaction sur la base de signaux de commande de rétroaction préférentiellement tous détectés au niveau d'un étage côté primaire (102) d'un étage d'isolation de l'étage résonnant à commutation isolé ; une unité de commande (108) qui commande au moins un commutateur (S1, S2) de l'étage résonnant à commutation sur la base des signaux de commande de rétroaction fournis à l'unité de commande (108), lesdits signaux de commande de rétroaction comprenant a) un signal représentant la tension VLED qui parcourt la charge de DEL, b) un signal indiquant une tension VBUS d'alimentation en courant continu du côté primaire, et c) au moins un signal représentant le courant détecté du côté primaire et représentant le courant circulant du côté primaire de l'étage d'isolation de l'étage résonnant à commutation isolé.
EP20734235.3A 2019-06-27 2020-06-29 Convertisseur à del Pending EP3967110A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP19182817 2019-06-27
PCT/EP2020/068218 WO2020260686A1 (fr) 2019-06-27 2020-06-29 Convertisseur à del

Publications (1)

Publication Number Publication Date
EP3967110A1 true EP3967110A1 (fr) 2022-03-16

Family

ID=67105838

Family Applications (1)

Application Number Title Priority Date Filing Date
EP20734235.3A Pending EP3967110A1 (fr) 2019-06-27 2020-06-29 Convertisseur à del

Country Status (2)

Country Link
EP (1) EP3967110A1 (fr)
WO (1) WO2020260686A1 (fr)

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2115863A1 (fr) * 2007-02-27 2009-11-11 Nxp B.V. Détection de courant de charge dans des convertisseurs d'énergie électrique
DE102012007478B4 (de) * 2012-04-13 2023-08-03 Tridonic Gmbh & Co Kg Wandler für ein Leuchtmittel, LED-Konverter und Verfahren zum Betreiben eines Wandlers
US9185767B2 (en) * 2013-04-19 2015-11-10 Cirrus Logic, Inc. Self-oscillating resonant converter-based light emitting diode (LED) driver

Also Published As

Publication number Publication date
WO2020260686A1 (fr) 2020-12-30

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