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
  • H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
  • H05B47/20—Responsive to malfunctions or to light source life; for protection
  • H05B47/26—Circuit arrangements for protecting against earth faults
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
  • G01R31/26—Testing of individual semiconductor devices
  • G01R31/2607—Circuits therefor
  • G01R31/2632—Circuits therefor for testing diodes
  • G01R31/2635—Testing light-emitting diodes, laser diodes or photodiodes
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
  • G01R31/44—Testing lamps
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
  • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
  • G01R31/52—Testing for short-circuits, leakage current or ground faults
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M1/00—Details of apparatus for conversion
  • H02M1/32—Means for protecting converters other than automatic disconnection
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M3/00—Conversion of dc power input into dc power output
  • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
  • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
  • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
  • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
  • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
  • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
  • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
• • 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]
  • H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M1/00—Details of apparatus for conversion
  • H02M1/0003—Details of control, feedback or regulation circuits
  • H02M1/0009—Devices or circuits for detecting current in a converter
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M1/00—Details of apparatus for conversion
  • H02M1/14—Arrangements for reducing ripples from dc input or output
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M3/00—Conversion of dc power input into dc power output
  • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
  • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
  • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
  • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
  • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
  • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
  • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
  • H02M3/1582—Buck-boost converters
• • 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]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
  • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
  • Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Definitions

• the invention relates to a method for detecting an isolation fault condition of a LED module and a LED module.
• Luminaires which comprise LED modules that are mounted onto a metal surface. This metal surface usually is connected to earth (or neutral wire if no earth is available in the installation). Under normal operating conditions, the LED output is (galvanically) isolated from this mounting surface.
• a current can flow through the LED driver and LED module back to the protective earth PE (or neutral wire depending on the structure of the luminaire).
• LED drivers or converters have no protection against such an error case and are not capable to react on such an event.
• the invention relates to a method (200) for detecting an isolation fault condition of a LED module (802) supplied with electrical power by a non-isolated switched LED converter (801), the switched LED converter (801) having a control circuit (701) for issuing a control signal for at least one switch and being supplied with at least one feedback signal (803) from the LED module (802) in order to implement a feedback- controlled operation of the LED module (802), the method (200) comprising the steps of: obtaining and analysing (201) a signal (300, 400) indicating the ripple frequency of the feedback signal (803) from the LED module (802) in order to evaluate the contribution of a harmonic in the frequency range of a mains voltage supplying the converter (801) in said signal (300, 400), and stopping or reducing (202) the electrical power supplied to the LED module (802) in case the contribution of said harmonic exceeds a given threshold value during at least a preset time period or preset number of cycles.
• the LED converter comprises a buck converter, preferably a synchronous buck converter.
• the LED converter can even comprise a boost-converter or buck-boost converter.
• the signal indicating the ripple frequency of the feedback signal from the LED module is the signal of the sensed LED current flowing through the LED module.
• the signal indicating the ripple frequency of the feedback signal from the LED module is the signal of the sensed LED voltage. This provides the advantage that the LED module can accurately be monitored.
• control circuit is an ASIC and the indicating the ripple frequency of the feedback signal from the LED module is analysed by a microcontroller.
• the step of analysing a signal indicating the ripple frequency of the feedback signal from the LED module comprises the steps of:
• the electrical power is stopped by shutting down the LED converter.
• the threshold value is set adaptively by the LED converter or is set via a user interface.
• the threshold value is adaptively set by the LED converter as a defined percentage of the average of said signal.
• the threshold is set at least 0.5% of the average value of said signal.
• the signal is analysed with a sampling rate at least as high as double of the mains frequency.
• the control circuitry implements a control algorithm to reduce any deviation from the feedback signal, preferably a LED current indicating signal, to a nominal value, such as e.g. a dimming signal value.
• the invention relates to a non-isolated switched feedback- controlled LED converter implementing a method according to the first aspect and the implementation forms thereof.
• the invention relates to a LED lighting device comprising a LED converter according to the second aspect and a LED module supplied by said converter.
• the LED module is mounted, in a galvanically isolated manner, on a metal surface which is connected to the earth or neutral phase of the mains voltage supplying the LED converter.
• the invention relates to a LED luminaire having a LED lighting device according to the third aspect and the implementation form thereof.
• Fig. 1 shows a luminaire according to prior art
• Fig. 2 shows an embodiment of a method for detecting an isolation fault condition of a LED module supplied with electrical power by a non-isolated switched converter
• Fig. 3 shows a profile over time of a signal representing a first normal operation of a
• Fig. 4 shows a profile over time of a signal representing a second normal operation of a LED module according to an embodiment
• Fig. 5 shows a profile over time of a signal representing a fault operation of a LED module according to an embodiment
• Fig. 6 shows a schematic diagram of a microcontroller, LED converter and LED module in a luminaire according to an embodiment
• Fig. 7 shows a LED lighting device according to an embodiment.
• LED luminaire shall mean a luminaire with a light source comprising one or more LEDs or OLEDs. LEDs are well-known in the art, and therefore, will only briefly be discussed to provide a complete description of the invention.
• Fig. 2 shows an embodiment of a method 200 for detecting an isolation fault condition of a LED module 802 supplied with electrical power by a non-isolated switched converter 801 (see also description of Fig. 6 and Fig. 7).
• the switched LED converter 801 has a control circuit (e.g. ASIC) 701 for issuing a control signal for at least one switch HS FET, LS FET and is supplied with at least one feedback signal 803 from the LED module 802 in order to implement a feedback-controlled operation of the LED module 802.
• the feedback signal represents the LED current obtained via a shunt Rshunt-
• the control circuit 701 implements the feedback control by comparing the feedback signal to a reference value and applying e.g. a PI control method on any deviation thereof.
• the switched converter is a non-isolated converter, in the present example a synch buck.
• Other examples are boost, buck, boost-buck, LLC converter etc.
• the method 200 comprises the following steps: obtaining and analysing 201 a signal 300, 400 indicating the ripple frequency of the feedback signal 803 from the LED module 802 in order to evaluate the contribution of a harmonic in a frequency range of a mains voltage supplying the converter 801 in said signal 300, 400, and stopping or reducing 202 the electrical power supplied to the LED module 802 in case the contribution of said harmonic exceeds a given threshold value during at least a preset time period or preset number of cycles.
• Fig. 3 shows a schematic profile over time of the signal 300 representing a first normal operation of the LED module 802 according to an embodiment.
• the signal 300 shown in Fig. 3 is the sensed feedback signal 803 from the LED module 802 provided the control circuit 701.
• the sensed feedback signal 803 is the measured LED current ILED_meas. Due to the control loop of the LED converter 801 the average value of the sensed feedback signal 803 from the LED module 802 is equal to the nominal LED current ILED_target.
• the sensed feedback signal 803 from the LED module 802 comprises a ripple which has a frequency of 100 Hz. This ripple is not exceeding the threshold limit ripple_detection_threshold. Therefore the value of the first counter ripple_period_cnt remains zero and no first counter is started, as well as the value of the second counter error_event_cnt remains zero.
• a ripple component having a frequency of twice the mains frequency is present.
• Fig. 4 shows a schematic profile over time of the signal 300 representing a second normal operation of the LED module 802 according to an embodiment.
• the signal 300 shown in Fig. 3 is the sensed feedback signal 803 from the LED module 802 provided the control circuit 701.
• the sensed feedback signal 803 is the measured LED current ILED_meas. Due to the control loop of the LED converter 801 the average value of the sensed feedback signal 803 from the LED module 802 is equal to the nominal LED current ILED_target.
• the sensed feedback signal 803 from the LED module 802 comprises a ripple which has a frequency of 100 Hz. In comparison with the example of fig. 3 the ripple is higher. This can be the case for instance for a driver comprising aged components, e.g. aged electrolytic capacitors which have a lower capacity over the life time, or at low ambient temperature.
• This ripple is repeatedly exceeding the threshold limit ripple_detection_threshold.
• a first counter starts to count a counter value upwards (or downwards) with a given time resolution of e.g. 1 ms until the threshold limit ripple_detection_threshold is being exceeded again.
• the value of the first counter ripple_period_cnt begins to increase to a certain value (in this example 10) but the value of the second counter error_event_cnt remains zero as the value of the first counter ripple_period_cnt is not exceeding a certain limit as it is being reset to zero before the value of the first counter ripple_period_cnt reaches a certain first counter limit which would increase the second counter value error_event_cnt. No error is detected in this case and normal operation continues.
• a ripple component having a frequency of twice the mains frequency is present.
• Fig. 5 shows a profile over time of a signal 400 representing a fault operation of a LED module 802 according to an embodiment.
• Fig. 5 shows the case of an isolation fault condition.
• the amplitude of the ripple is much bigger than that of the signal 300 and there is a substantial ripple component with a frequency identical to the mains frequency, thus, in the order of 50 or 60 Hz.
• a first counter starts to count upwards (or downwards) with a given time resolution of e.g. 1 ms until the threshold limit ripple_detection_threshold is being exceeded again. Therefore the first value ripple_period_cnt begins to increase to a certain value (in this example 20) and the second value error_event_cnt is counted up (or down) as the first value ripple_period_cnt is exceeding a certain limit of e.g. 15 before it is being reset to zero.
• the value of the first counter ripple_period_cnt begins to increase again.
• the certain limit of e.g. 15 the value of the second counter error_ event_ ent is counted up (or down) again.
• the value of the second counter error_event_cnt reaches the value 3 as given threshold value which may be taken as indication for an error which is in this case an isolation fault condition.
• the sensed feedback signal 803 from the LED module 802 stays at a constant level or with a low ripple at twice the mains frequency.
• This low ripple is, for instance, caused by a regulation of the PFC bus ripple in order to achieve an output current without a low-frequency ripple.
• this ripple is in the range of maximum +/ - 1% of its nominal average value with a frequency of twice the mains frequency.
• this ripple increases and changes its frequency from twice the mains frequency to the mains frequency.
• the ripple is 3.5% of its nominal average value.
• the signal has a mains frequency (50Hz/ 60Hz) and not a multiple of it; and/ or
• Fig. 5 shows a profile over time of a fault operation detection of a LED module 802 according to an embodiment.
• the shutdown threshold value can be adjustable as a relative factor to the average value of the nominal LED current (ILED_ target).
• the given limit for the value of the second counter error_event_cnt may be adaptively set by the LED converter 801 as a defined percentage of the average of the nominal LED current.
• the given or preset threshold value is set at at least 0.5% of the average value of the signal 300, 400.
• Fig. 6 shows a schematic diagram 600 of a fault operation detection of a LED module 802 according to an embodiment.
• the shutdown threshold value level can be a user definable constant and can be set via a user interface 601.
• the shutdown threshold value level can be defined by the user as a fixed constant. If the peak tracked and bandpass filtered input signal exceeds this user defined level, the shutdown can be triggered. The shutdown of the LED module 802, after the given threshold value is exceeded, can be done immediately or after n-consecutive samples.
• the LED converter 80 e.g. a buck converter, preferably a synchronous buck converter, stops switching, which directly interrupts the current path from mains to the LED module 802 and, thus, stopping the flow of the fault current.
• a buck converter preferably a synchronous buck converter
• the signal 803 may be processed in the microcontroller 700.
• Fig. 1, Fig. 5 and Fig. 6 can be implemented, respectively carried out, by the microcontroller 700.
• Fig. 7 shows a schematic diagram of a, LED converter 801 with a microcontroller 700 and LED module 802 according to an embodiment.
• control circuit 701 is an ASIC and the feedback signal 803 is analysed by the microcontroller 700.
• control circuit 701 implements a control algorithm to reduce any deviation from the feedback signal 803, preferably a LED current indicating signal, to a nominal value (reference signal), such as e.g. a dimming signal value.
• a nominal value e.g. a dimming signal value.
• the feedback signal 803 or signal 300, 400 is periodically sampled by the microcontroller 700 from the ASIC 701 in discrete time steps (e.g. approx, every 1 ms). It should be noticed that, for applications without ASIC 701, the switching frequency of the LED converter 801 could be monitored by the microcontroller 700.
• the microcontroller 700 can be configured to read the signal 300, 400 indicating the ripple frequency of the feedback signal 803 from the LED module 802 from the ASIC 701 on a regularly basis. This read out interval should be lower than at least twice the mains period. Alternatively, a tracking of the LED converter 801 frequency would also be possible, this could directly be done by the microcontroller 700. As mentioned above, in order to overcome the isolation fault problem and solving it by a quick shutdown of the operation of the LED module 802, the LED current signal 300, 400 of the ASIC for the 50/60 Hz harmonic can be monitored.
• the LED module 802 can be immediately shut-down, typically by stopping the operation of one or more switches HS_FET, LS_FET of the LED converter 801.
• the switching frequency and/ or duty cycles of the switch(es) may be set such that the power supplied to a connected LED module is at least reduced.
• the signal 300, 400 may indicate the ripple frequency of the feedback signal 803 from the LED module 802.
• the microcontroller 700 can be configured to analyse the signal 300, 400 with a sampling rate at least as high as double of the mains frequency.
• Fig. 8 shows a LED lighting device 800 according to an embodiment.
• the LED lighting device 800 comprises the LED converter 801 and the LED module 802 supplied by said converter 801.
• the LED module 802 is mounted, in a galvanically isolated manner, on a metal surface which is connected to the earth or neutral phase of the mains voltage Vmains supplying the LED converter 801.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Optics & Photonics (AREA)
• Circuit Arrangement For Electric Light Sources In General (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=85775966

Family Applications (1)

Country Status (2)

Citations (1)

Family Cites Families (3)

• 2022
  • 2022-03-17 AT ATA50175/2022A patent/AT525667B1/de active
• 2023
  • 2023-03-16 WO PCT/EP2023/056784 patent/WO2023175092A1/en unknown

Patent Citations (1)

Also Published As

Similar Documents

Legal Events