CN108990217B - EMC self-checking method for headlamp LED driving module - Google Patents
EMC self-checking method for headlamp LED driving module Download PDFInfo
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- CN108990217B CN108990217B CN201811017491.5A CN201811017491A CN108990217B CN 108990217 B CN108990217 B CN 108990217B CN 201811017491 A CN201811017491 A CN 201811017491A CN 108990217 B CN108990217 B CN 108990217B
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- 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
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- 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
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Abstract
The invention relates to an EMC self-checking method of a headlamp LED drive module, which is characterized in that a main circuit ripple test and a port small voltage injection test are firstly carried out before the EMC self-checking test is carried out on the headlamp LED drive module, the main circuit ripple test is to measure a switch waveform aiming at a D pin of a DCDC switch MOS tube of the headlamp LED drive module to be tested, the passing standard of the test is that the rising time of a large current edge generated by the switch waveform is less than 70ns, the ripple voltages of an up-rush waveform and an down-rush waveform are both less than 500mV, and the ripple voltage of an output signal to the ground is less than 90 mV; if the main circuit ripple test passes, the passing rate of the follow-up EMC test is predicted to be greatly improved. The EMC self-test is mainly carried out according to the requirements of relevant standards. The passing rate of the LED driving module passing the test by adopting the self-verification method is obviously improved in the later formal test, and the EMC requirements of each major vehicle factory can be met.
Description
Technical Field
The invention relates to an EMC self-checking method specially aiming at a headlamp LED driving module.
Background
Different mainstream car factories have different requirements on the EMC (Electro Magnetic Compatibility, namely electromagnetic Compatibility) of headlights, so that car light manufacturing enterprises often need to respectively design, EMC test, produce and manage the headlight LED driving module according to the requirements provided by each car factory, and thus the car light cost, the car light production efficiency and the economic benefit of the car light manufacturing enterprises are all affected.
Disclosure of Invention
The invention aims to provide an EMC self-checking method for a headlamp LED driving module, which can obviously improve the passing rate of the LED driving module which passes the detection by adopting the checking method and is formally detected in the later period and can meet the EMC requirements of various major main-stream vehicle factories.
The main technical scheme of the invention is as follows:
the utility model provides a headlight LED drive module's EMC self-checking method, before carrying out EMC self-checking test to headlight LED drive module, carries out main circuit ripple test earlier, main circuit ripple test is under the headlight LED drive module that awaits measuring is in maximum output, measures the switching waveform to the D foot of the DCDC switch MOS pipe of headlight LED drive module that awaits measuring, and the standard that the test passes through is that the switching waveform produces heavy current border rise time and is less than 70ns, and the ripple voltage peak value of overshoot and undershoot waveform all is less than 500mV, and the ripple voltage peak value of output signal to ground is less than 90 mV.
Before EMC self-checking test is carried out to headlamp LED drive module, to the drive module of more than one input port, still carry out port minivoltage and pour into the test into, port minivoltage pours into the test and is providing 5V's supply voltage at unsettled another input port when needing single-point function into, checks that the headlamp LED drive module that awaits measuring appears unusually.
The EMC self-checking test comprises the steps of firstly carrying out an electrostatic discharge test, carrying out a power line transient pulse anti-interference test after the test is passed, and carrying out a large current injection test, a radio frequency anti-interference test, a radiation emission test and a power line conduction emission test after the test is passed.
Determining the following working states of the tested sample according to the design values of the output voltage, the output current and the output power of the tested sample:
operating state 2 a: the sample piece works in the states of maximum output voltage and minimum output current;
operating state 2 b: the sample piece works in a state of minimum output voltage and maximum output current;
operating state 2 c: the sample piece works in the states of maximum output power and maximum output current;
operating state 2 d: the sample piece works in the states of maximum output power and maximum output voltage;
operating state 2 e: the sample piece works in a state of minimum output voltage and minimum output current;
the working states of the tested sample piece during the electrostatic discharge test and the power line transient pulse anti-interference test are 2a and 2 b; during the high-current injection test and the radio frequency anti-interference test, the working states of the tested sample piece are 2a and 2 e; and when the radiation emission test and the power line conduction emission test are carried out, the working states of the tested sample piece are 2c and 2 d.
In the electrostatic discharge test, for a tested sample with a metal part on a shell, the tested sample needs to be placed on an insulating pad and directly placed on a grounding steel plate or a grounding copper plate for test verification respectively; the static discharge test comprises a static electricity-off mode test and a static electricity-on mode test, and the passing standard of the static electricity-off mode test is that the function of the tested sample is normal after the static electricity-off mode test is powered on; the passing standard of the static electrification mode test is that the functions of the tested sample piece are normal during and after the test.
During the static non-molding test, the voltage grades of contact discharge are three types of +/-4 kV, +/-6 kV and +/-8 kV, when the voltage grade is +/-4 kV, the discharge point is a PIN foot, when the voltage grade is +/-8 kV, the discharge point is a shell metal part including a screw, and when the voltage grade is +/-6 kV, the discharge point is the PIN foot and the shell metal part including the screw; during the static on-mode test, the voltage grades of contact discharge are +/-6 kV and +/-8 kV, and the discharge point is a shell metal part including a screw; no matter the static electricity-free mode test or the static electricity-charged mode test, the voltage grade of the air discharge test in the static discharge test is +/-8 kV and +/-15 kV, and a discharge point is the whole shell part including a gap; each voltage level in the electrostatic discharge test is preferably discharged 10 times, and the interval between two adjacent discharges is preferably 3s, and each of the tests should be repeated after polarity is changed.
The power line of the power line transient pulse anti-interference test comprises power lines of all tested samples and all wire harnesses directly connected to the storage battery through switch control on all the tested samples, the test comprises independent test aiming at each wire, and the test also comprises the test after all the wires are combined together.
In the power line transient pulse anti-interference test, when pulses with the amplitude of-150V are applied, the number of the applied pulses is preferably 5000, and the passing standard of the test is that the module driving LED can flicker or extinguish in the test, but needs to automatically recover to be normal after the test; when the pulse with the amplitude of +75V is applied, the number of the applied pulses is preferably 5000, and the standard that the module drives the LED and needs no abnormal phenomenon in the test and after the test is passed; when pulses with the amplitude of 10V are applied, the number of the applied pulses is preferably 10, the standard that the module drives the LED to flicker or extinguish in the test is passed, but the module needs to automatically return to normal after the test; when a pulse with the amplitude of-200V is applied, the time for applying the pulse is preferably 1h, and the standard that the module drives the LED and needs no abnormal phenomenon in the test and after the test is passed; when a pulse with the amplitude of +112V is applied, the pulse is preferably applied for 1h, and the passing standard of the test is that the module drives the LED and does not have any abnormal phenomenon in the test and after the test; when a pulse with the amplitude of 20.5V is applied, 10 pulses are applied every 1 minute, and the standard of passing the test is that the LED driven by the module without overvoltage protection can have jitter in the test but cannot be extinguished or flickered; the LED driven by the module with overvoltage protection can flicker in the test, but needs to be automatically restored to normal after the test.
When the large current is injected into the test, the negative end of the storage battery is connected with the grounding flat plate, and the storage battery is arranged on the grounding flat plate or below the test board; the length of a wire harness between the sample piece to be tested and the test auxiliary equipment is 1700mm, the wire harness is placed on an insulating pad with the thickness of 50mm of the grounding flat plate, and the relative dielectric constant epsilon r of the insulating pad is less than or equal to 1.4; the test bench should contain a ground plate, the edge of which exceeds the test device by at least 100mm in all directions; the distance between the testing device and all other conductive structures except the grounding flat plate is ensured to be more than or equal to 100 mm; the injection clamp is insulated from the grounding flat plate, and 0.03MHz is taken step by step when the tested frequency range is 0.1-1 MHz; when the tested frequency range is 1-200MHz, 1MHz is taken in a stepping mode; when the tested frequency range is 200-400MHz, stepping to take 2 MHz; when common-mode large current injection is performed, all wire harnesses output by a module need to be added into an injection clamp, the modulation modes of interference signals are CW and AM 80%, when differential-mode large current injection is performed, all wire harnesses except a ground wire need to be added into the injection clamp, the modulation modes of the interference signals are CW and AM 80%, the passing standard of the test of the large current injection test is that no abnormality exists in the test and after the test, the injection clamp needs to be respectively arranged at positions 150mm, 450mm and 750mm away from a tested sample within the frequency range of 0.1MHz-400MHz for testing, wherein the differential-mode large current injection test is performed at the positions 150mm and 450mm, and the common-mode large current injection test is performed at the positions 450mm and 750 mm; if the deviation phenomenon of the function of the tested sample piece is found in the test, the injection current is gradually reduced until the function of the tested sample piece is recovered to be normal; then, the injection current should be increased step by step until the deviation phenomenon occurs again in the function of the sample to be measured, and the injection current value is recorded as a threshold value.
In the radio frequency anti-interference test, for the test with the frequency less than or equal to 1000MHz, the transmitting antenna is arranged right in front of the central position of the wiring harness of the tested sample, and for the test with the frequency more than or equal to 1000MHz, the antenna is translated for 750mm along the front edge of the grounding flat plate and is opposite to the tested sample; the center of the antenna is opposite to a tested sample, the length of a wire harness is 1700mm, the tested sample and the wire harness of the test auxiliary equipment are placed in a bent mode, the bending angle of the wire harness is 90-135 degrees, and the test wire harness is placed on an insulating pad with the thickness of 50mm of a grounding flat plate; when the tested frequency range is 200-400MHz, stepping to take 2 MHz; when the tested frequency range is 400-1000MHz, 5MHz is taken in a stepping mode; when the tested frequency range is 1000-3200MHz, 10MHz is taken step by step; the residence time of all modulation modes is not less than 2s, the test polarization mode comprises a horizontal polarization mode and a vertical polarization mode, when the test frequency range is larger than or equal to 1000MHz, the tested sample is respectively tested in three axial directions, if the deviation phenomenon of the function of the tested sample is found in the test, the test field strength is gradually reduced until the function of the tested sample is recovered to be normal, then the field strength is gradually increased until the deviation phenomenon of the function of the tested sample occurs again, and the field strength value is used as a threshold value to be recorded.
The power supply of electronic hardware in a sample piece to be tested and test auxiliary equipment in the radiation emission test needs to use a vehicle-mounted storage battery, the negative end of the storage battery needs to be connected with a grounding flat plate, the storage battery is arranged on the grounding flat plate or below a test bench, the total length of a wire harness for the test is 1700mm, the positions of the wire harness and the sample piece to be tested are fixed, the bending radius angle of the wire harness is 90-135 degrees, and the wire harness is arranged on an insulating pad with the thickness of 50mm on the grounding flat plate; the frequency range corresponding to each service, the detection mode adopted by the test, the bandwidth, the step length and the residence time are executed according to the following table:
the tested sample needs to be tested in at least three different axial directions, when the testing frequency is larger than or equal to 30MHz, the values of the receiving antenna in the two directions of horizontal polarization and vertical polarization need to be tested respectively, when the testing frequency is smaller than or equal to 1GHz, the antenna is aligned to the center of a wire harness, when the testing frequency is larger than 1GHz, the values of the tested sample in the three polarization directions need to be tested respectively, and the passing standard of the test is that the emission value of each detection mode should be lower than the limit value of the corresponding frequency.
When the power line conducts and emits for testing, a vehicle-mounted storage battery is needed to be used for supplying power in the tested sample piece and the test auxiliary equipment, the negative end of the storage battery needs to be connected with the grounding flat plate, and the length of a power supply/power supply loop wire harness between the tested sample piece and the artificial network is 500 mm; the frequency range corresponding to each service, the detection mode adopted by the test, the bandwidth, the step length and the residence time are executed according to the following table:
the criterion for passing the test is that the emission value for each detection mode should be below the limit for the corresponding frequency.
The invention has the beneficial effects that:
the invention fills the blank of an EMC self-checking program specially aiming at the LED driving module, and can meet the EMC requirements of all mainstream car factories on the car lamps at present.
As long as the LED driving module passes the detection by adopting the self-checking method, the passing rate of the later formal test is obviously improved, and the requirements of the EMC regulations of all the current mainstream car factories on related parts can be met.
Through setting up main circuit ripple test at present at the test item that EMC regulation required, help discovering comparatively serious design problem earlier, can foresee the test condition of passing of the test item that EMC regulation required to a certain extent.
The self-verification method provided by the invention is used as a unified test standard in the design verification stage of the headlamp LED driving module, so that the design quality is improved, the quality stability of delivered products is improved, the production and process management can be simplified, the single-piece cost is reduced, and the production efficiency and the economic benefit are improved.
Drawings
FIG. 1 is a test flow diagram of a test method of the present invention;
FIG. 2 is a waveform diagram of transient pulse 1 applied in a power line transient pulse immunity test;
FIG. 3 is a waveform diagram of transient pulse 2a applied by a power line transient pulse immunity test;
FIG. 4 is a waveform diagram of transient pulses 2b applied by the power line transient pulse immunity test;
FIG. 5 is a waveform diagram of transient pulse 3a applied by the power line transient pulse immunity test;
FIG. 6 is a waveform diagram of transient pulses 3b applied by the power line transient pulse immunity test;
fig. 7 is a waveform diagram of transient pulse 5b applied by the power line transient pulse immunity test.
Detailed Description
The invention discloses an EMC self-checking method of a headlamp LED drive module, as shown in figure 1, before an EMC self-checking test is carried out on the headlamp LED drive module (a sample to be tested for short), a main circuit ripple test is carried out, the main circuit ripple test is carried out aiming at the waveform of a switching signal of a D pin of a DCDC switching MOS (metal oxide semiconductor) tube of the headlamp LED drive module to be tested under the condition that the headlamp LED drive module to be tested is at the maximum output power, the passing test standard is that the rising time of a large current edge generated by the switching waveform is less than 70ns, the ripple voltage peak values of an up-rush waveform and a down-rush waveform are both less than 500mV, and the ripple voltage peak value of an output signal to the ground is less than 90 mV.
If the ripple of the main circuit of the tested sample piece is poor, the probability that the RE and CE tests in the EMC test exceed the standard is extremely high. If the measured parameters are far outside the required range, design modifications of the EMC can be immediately undertaken. From another perspective, if the tested sample can meet the ripple test requirements, it is predicted that the future EMC test will have a greatly improved passing rate.
Before EMC self-checking test is carried out on the headlamp LED driving module, port small voltage injection test is preferably carried out on the driving module with more than one input port, the port small voltage injection test is to provide 5V power supply voltage at another suspended input port when a single-point function is needed, and whether the headlamp LED driving module to be tested is abnormal or not is checked. The test can verify the possible situation of the tested sample in the subsequent high-current injection test to a certain extent.
The port small voltage injection test and the main circuit ripple test have no sequential requirements.
The EMC self-test is mainly performed in compliance with the requirements of the relevant standards. The method comprises the steps of firstly carrying out an Electro-static discharge (ESD) test, then carrying out a power line transient impulse on power line (CI) test, and finally carrying out a Bulk Current Injection (BCI) test, a radio frequency interference (RI) test, a Radiation Emission (RE) test and a power line Conducted Emission (CE) test. Taking the ESD as a first test item and the CI test as a second test item, that is, each subsequent tested sample (i.e. the LED driving module to be tested) is a tested sample that has been subjected to the ESD and CI tests.
The output voltage and the output current of the LED driving module have a certain range, and the preferable design values are as follows: the stable output voltage range is 3-55V, the stable output current range is 80-1200mA, and the maximum output power is 15W. Different tests should lead the tested sample to be in different specific working states, and the working states are determined according to the design values of the output voltage, the output current and the output power of the tested sample.
The EMC self-verification method of the invention relates to the following working states of the tested sample:
working state 1 a: the sample piece is not electrified, and the connector and the wiring harness are not connected;
operating state 1 b: the sample piece is not electrified, and the connector is connected with the wiring harness;
operating state 2 a: the sample piece works in the states of maximum output voltage and minimum output current;
operating state 2 b: the sample piece works in a state of minimum output voltage and maximum output current;
operating state 2 c: the sample piece works in the states of maximum output power and maximum output current;
operating state 2 d: the sample piece works in the states of maximum output power and maximum output voltage;
operating state 2 e: the sample piece works in a state of minimum output voltage and minimum output current.
During ESD and CI test, the working state of the special part is the actual working state of the module, and the working state of the platform part is 2a and 2 b. During BCI and RI tests, the working state of the special part is the actual working state of the module, and the working states of the platform part are 2a and 2 e. And during RE and CE tests, the working state of the special part is the actual working state of the module, and the working state of the platform part is 2c and 2 d. The special part and the platform part are tested sample parts, and the difference is that the special part is a tested sample part specially ordered and is only suitable for a certain unique application.
The specific contents of each self-check verification are described one by one.
Firstly, electrostatic discharge testing:
during the test, the test facility is placed in an environment with the temperature of 23 +/-3 ℃ and the relative humidity of 20-40 percent (20 ℃ and 30 percent relative humidity are preferred).
The waveform verification of the electrostatic discharge simulator is required to meet the requirements of ISO 10605, the rise time of contact discharge is required to be less than or equal to 1ns, the rise time of air discharge is required to be less than or equal to 20ns, and the RC time constant is required to be verified by calculation of a leading edge and/or a waveform exponential decay part after damped oscillation.
Before the test is started, the discharge voltage of the ESD simulator is verified. The test procedure can be divided into the following 3 steps.
Step a), performing contact discharge of corresponding voltage classes and air discharge tests of 8kV and 15kV voltage classes on all surfaces and gaps of a sample piece to be tested (including connector pins). The discharge point of the air discharge test is the entire housing portion (including the slit).
When the static electricity-free mode test is carried out, the voltage grades of contact discharge are +/-4 kV, +/-6 kV and +/-8 kV, when the voltage grade is +/-4 kV, the discharge point is a PIN foot, when the voltage grade of discharge is +/-8 kV, the discharge point is a shell metal part (comprising a screw), and when the voltage grade is +/-6 kV, the discharge point is the PIN foot and the shell metal part (comprising the screw). The voltage grades of the air discharge test are +/-8 kV and +/-15 kV, and the discharge point is the whole shell part including the gap.
When the test is an electrostatic electrification mode test, the voltage grades of contact discharge are +/-6 kV and +/-8 kV, and the discharge point is a shell metal part (comprising a screw). The voltage grades of the air discharge test are +/-8 kV and +/-15 kV, and the discharge point is the whole shell part including the gap.
And b), discharging 10 times for each voltage level, wherein the interval between every two adjacent discharges is 3 s.
Step c), reversing one polarity to complete steps a) and b) again.
For the tested sample with a metal part on the shell, the tested sample needs to be placed on an insulating pad and directly placed on a grounding copper plate (or a steel plate) for test and verification respectively. The grounding copper plate (or steel plate) and the ground are directly connected by adopting 2 470 Komega electric wires.
For the static electricity non-electrifying mode test, the passing standard of the test is that the function of the tested sample is normal after electrification. For the static electrification mode test, the passing standard of the test is that the functions of the tested sample piece are normal during and after the test.
Secondly, testing transient pulse anti-interference of a power line:
the power supply lines of the test comprise power supply lines of all samples to be tested and all wire harnesses directly connected to the storage battery through switch control on all the samples to be tested. Both individually for each line and collectively for all lines.
Six pulses were applied during the test, pulse 1, pulse 2a, pulse 2b, pulse 3a, pulse 3b and pulse 5b, respectively, with waveforms as shown in fig. 2-7.
The tested sample needs to meet the functional requirements of table 1.
TABLE 1
The pulse amplitude Us of the pulse 1 is-150V, the number of the applied pulses 1 is preferably 5000 during the test, and the test passes the standard that the module driving LED can flicker or extinguish during the test, but needs to automatically return to normal after the test.
U in FIG. 2APulse 1 preferably sets the following parameters at 13.5V: the pulse amplitude Us is-150V, the pulse width Td is 2ms, Tr is 1Us, the pulse period T1 is 0.5-5s, T2 is 200ms, T3 is less than 100Us, and the internal resistance Ri of the power supply is 4 omega. Wherein the determination of T1 ensures that the sample under test should have returned to functioning properly before the next pulse.
The pulse amplitude Us of the pulse 2a is +75V, the pulse peak value Umax is Ua + Us, the number of applied pulses 2a during the test is preferably 5000, and the standard that the test passes is that the module driving LED needs not to have any abnormal phenomenon during and after the test.
In fig. 3, Ua is 13.5V, and pulse 2a preferably has the following parameters: us is +75V, Td is 0.05ms, Tr is 1Us, T1 is more than or equal to 0.2s, and the internal resistance Ri of the power supply is 2 omega.
The pulse amplitude Us of the pulse 2b is +10V, the number of the applied pulses 2b during the test is preferably 10, and the test passes the standard that the module driving LED can flicker or extinguish during the test, but needs to automatically return to normal after the test.
In fig. 4, Ua is 13.5V, and pulse 2b is preferably set to the following parameters: us is 10V, Td is more than 0.2s, T12 is 1ms, Tr is 1ms, T6 is 1ms, and the internal resistance Ri of the power supply is less than 0.5 omega.
The pulse amplitude Us of the pulse 3a is-200V, the time for applying the pulse 3a during the test is preferably 1h, and the standard for passing the test is that the module driving the LED needs not to have any abnormal phenomenon during and after the test.
In fig. 5, Ua is 13.5V, and the pulse 3a preferably has the following parameters: Us-200V, Td 0.1Us, Tr 5ns, T1 100Us, T4 10ms, T5 90ms, and internal power Ri 50 Ω.
The pulse amplitude Us of the pulse 3b is +112V, the time for applying the pulse 3a during the test is preferably 1h, and the standard for passing the test is that the module driving the LED needs not to have any abnormal phenomenon during and after the test.
In fig. 6, Ua is 13.5V, and the pulse 3b is preferably set to the following parameters: us +112V, Td 0.1Us, Tr 5ns, T1 100Us, T4 10ms, T5 90 ms.
The pulse 5b has a pulse amplitude Us of +20.5V and a pulse peak Umax of Ua + Us of +34V, and preferably 10 pulses are applied every 1 minute when testing, and the test passes the criteria: the module-driven LED without overvoltage protection can have jitter in the test, but cannot be extinguished or flickering; the LED driven by the module with overvoltage protection can flicker in the test, but needs to be automatically restored to normal after the test.
In fig. 7, Ua is 13.5V, and pulse 5b is preferably set to the following parameters: us 20.5V, Td 400ms, Tr 10ms, and internal power Ri 2 Ω.
Thirdly, testing high-current injection:
this test requires the following arrangement: the negative terminal of the battery should be connected to a ground plate on which the battery can be placed or under the test stand. The length of the wiring harness between the sample to be tested and the test auxiliary equipment is 1700mm, and the wiring harness is placed on an insulating pad (the relative dielectric constant epsilon r is less than or equal to 1.4) with the thickness of 50mm of a grounding flat plate. The test rig should contain a sufficiently large ground plate with an edge that extends at least 100mm beyond the test apparatus in all directions. The distance between the testing device and all other conductive structures except the grounding flat plate should be guaranteed to be larger than or equal to 100 mm. The injection clamp should be insulated from the ground plane.
When testing, the calibration injection clamp method (alternative method) meeting the requirements of IS011452-4 IS used for testing, and it IS noted that:
a) the forward power will be the characteristic parameter of the electromagnetic field and will be used in the actual test.
b) When the tested frequency range is 0.1-1MHz, stepping to take 0.03 MHz; when the tested frequency range is 1-200MHz, 1MHz is taken in a stepping mode; when the tested frequency range is 200-400MHz, stepping to take 2 MHz.
c) In the frequency range 0.1MHz-400MHz, the injection clamp should be placed at 150mm, 450mm and 750mm from the sample to be tested, respectively, where DBCI testing is performed at 150mm and 450mm and CBCI testing is performed at 450mm and 750 mm.
When common mode large current injection (CBCI) is executed, all wire harnesses output by a module need to be added into an injection clamp, the modulation modes of interference signals are CW and AM 80%, and the test requirement is that no abnormity exists during and after the test. Modulation and class requirements are shown in table 2.
Table 2: modulation and grade requirement comparison table when common mode large current injection is executed
Frequency (MHz) | 0.1-2.38 | 2.38-15 | 15-54 | 54-65 | 65-88 |
Grade (dBuA) | 90 | 90-106 | 106 | 105.4-105.2 | 106 |
Frequency (MHz) | 88-140 | 140-174 | 174-388 | 380-400 | |
Grade (dBuA) | 104.6-103.3 | 104-103 | 97 | 99.64-99.4 |
When differential mode large current injection (DBCI) is executed, all wire harnesses except a ground wire need to be added into an injection clamp, the modulation modes of interference signals are CW and AM 80%, and the test requirement is that no abnormity exists during and after the test. Modulation and class requirements are shown in table 3.
Table 3: modulation and grade requirement comparison table when implementing differential mode large current injection
Frequency (MHz) | 1-15 | 15-30 |
Grade (dBuA) | 70-106 | 106 |
d) If the deviation phenomenon of the function of the tested sample piece is found in the test, the injection current is gradually reduced until the function of the tested sample piece is recovered to be normal; then, the injection current should be increased step by step until the deviation phenomenon occurs again in the function of the sample under test. This injection current value should be recorded as a threshold in the test report.
Fourthly, radio frequency anti-interference testing:
this test requires the following arrangement: for the test with the frequency less than or equal to 1000MHz, the transmitting antenna is arranged right in front of the center position of the beam of the tested sample (refer to ISO 11452-2). For the test with frequency more than 1000MHz, the antenna should be translated 750mm along the front edge of the grounding plate, and is opposite to the tested sample. The center of the antenna is opposite to the tested sample and is not opposite to the center of the test wire harness. The length of the wire harness is 1700mm, and the wire harness of the tested sample piece and the test auxiliary equipment is placed in a bent mode. The bending angle of the wiring harness is between 90 and 135 degrees, and the test wiring harness is placed on an insulating pad with the thickness of 50mm of the grounding flat plate. In the test with frequency > 1000MHz, the tested sample needs to be tested in at least three different axial directions.
The standard of passing the test is that the tested sample has no abnormal phenomenon in the test.
The test is carried out by adopting an alternative method, and the calibration and the test can be carried out according to the requirements of ISO 11452-2, and the following steps are required:
a) in calibration and actual test, the forward power is used as the characteristic parameter of the electromagnetic field, and is used in the actual test, and is recorded as the reference parameter.
b) When the tested frequency range is 200-400MHz, stepping to take 2 MHz; when the tested frequency range is 400-1000MHz, 5MHz is taken in a stepping mode; when the tested frequency range is 1000-3200MHz, 10MHz is taken in a stepping mode.
The requirements to be met by each modulation mode are shown in table 4.
Table 4: class requirement of radio frequency anti-interference test
c) Dwell time of all modulation schemes (dwell time: time for each radio frequency modulation) should not be less than 2 s;
d) the test polarization mode comprises a horizontal polarization mode and a vertical polarization mode;
e) when the testing frequency range is more than 1000MHz, the tested sample is respectively tested in three XYZ axes;
f) if the deviation phenomenon of the function of the tested sample piece is found in the test, the test field strength is gradually reduced until the function of the tested sample piece is recovered to be normal; the field strength should then be increased gradually until the deviation phenomenon again occurs in the function of the sample under test. This field strength value should be recorded as a threshold value in the test report.
Fifthly, radiation emission testing:
this test requires the following arrangement: the power supply of the electronic hardware in the tested sample piece and the test auxiliary equipment needs to use a vehicle-mounted storage battery. The negative terminal of the battery must be connected to the ground plane. The battery may be placed on the ground plane or under the test stand. The total length of the test harness should be 1700 mm. The position of the wiring harness and the tested sample is fixed, the radius angle of the bending of the wiring harness is between 90 and 135 degrees, and the wiring harness is placed on an insulating pad with the thickness of 50mm on a grounding flat plate.
The frequency range corresponding to each service, the detection method adopted by the test, and the test parameters such as Bandwidth (BW), step length, residence time and the like are shown in table 5.
Table 5:
different bandwidths (9/120/1000KHz) for different detection modes (peak detection PK/mean detection AV/quasi-peak detection QP) were subject to different limits (see limit values in tables 6-8) during the test. The criterion for the test to pass is that the emission value for the detection mode should be lower than the limit value for the corresponding frequency.
The main notes in the test process are:
a) it should be confirmed that the background noise of the entire test arrangement (including all equipment except the test sample) is at least 6dB below the specified limit before testing the radiation disturbance value of the test sample. I.e. if the overall background noise does not meet this limit requirement, the test is not performed until the problem is solved.
b) When the test frequency is more than or equal to 30MHz, the values of the receiving antenna in the horizontal polarization direction and the vertical polarization direction need to be tested respectively;
c) when the test frequency is less than or equal to 1GHz, the antenna is aligned to the center of the wire harness; when the test frequency is greater than 1GHz, the antenna is aligned to the sample to be tested, and the values of the three polarization directions of the sample to be tested need to be tested respectively, namely the sample to be tested needs to be tested in at least three different axial directions.
TABLE 6
TABLE 7
TABLE 8
Sixthly, conducting and transmitting test of a power line:
this test requires the following arrangement: the power supply in the tested sample piece and the test auxiliary equipment needs to use a vehicle-mounted storage battery. The negative terminal of the battery must be connected to the ground plane. The length of the power supply/power supply loop wiring harness between the tested sample and the artificial network should be 500 mm.
The frequency range corresponding to each service, the detection method adopted by the test, and the test parameters such as Bandwidth (BW), step length, residence time and the like are shown in table 4.
During the test, different bandwidths (9/120/1000KHz) for different detection modes (peak detection PK/mean detection AV/quasi-peak detection QP) are corresponding to different limits (see limit values in tables 9-11). The criterion for the test to pass is that the emission value for the detection mode should be lower than the limit value for the corresponding frequency.
Unless otherwise stated, the requirements of the voltage method in IEC CISPR 25:2008 should be used to verify the performance of the samples tested.
The main notes in the test process are:
a) it should be confirmed that the background noise of the entire test arrangement (including all equipment except the sample under test) is at least 6dB below the specified limit before testing the conducted disturbance value of the sample under test. I.e. if the overall background noise does not meet this limit requirement, the test is not performed until the problem is solved.
b) Testing the conducted disturbance value of the tested sample according to the required parameters of each frequency band in the table 5;
c) the test should cover all the operating states defined for the sample under test in the test plan.
TABLE 9
Watch 10
TABLE 11
According to the self-checking certificate method, as long as the tested sample can pass through the EMC self-checking certificate, the probability that the tested sample passes through the subsequent formal EMC test can be greatly improved, and the requirements of the EMC regulations of various large vehicle factories on parts can be met.
Claims (8)
1. The EMC self-checking method of the headlamp LED driving module is characterized by comprising the following steps: before EMC self-checking test is carried out on a headlamp LED drive module, main circuit ripple test is carried out firstly, the main circuit ripple test is that under the condition that the headlamp LED drive module to be tested is at the maximum output power, the switch waveform is measured aiming at a pin D of a DCDC switch MOS tube of the headlamp LED drive module to be tested, the standard that the test passes is that the rising time of a large current edge generated by the switch waveform is less than 70ns, the ripple voltage peak value of an up-rush waveform and an down-rush waveform is less than 500mV, and the ripple voltage peak value of an output signal to the ground is less than 90mV, if the measured parameter exceeds the required range, the EMC design correction is immediately carried out.
2. The EMC self-verification method of a headlamp LED driver module of claim 1, characterized in that: before EMC self-checking test is carried out to headlamp LED drive module, to the drive module of more than one input port, still carry out port small voltage and pour into the test, port small voltage pours into the test and provides 5V's supply voltage at unsettled another input port when needing single-point function, checks that the headlamp LED drive module that awaits measuring appears unusually.
3. EMC self-verification method of a headlamp LED driver module according to claim 1 or 2, characterized in that: the EMC self-checking test comprises the steps of firstly carrying out an electrostatic discharge test, carrying out a power line transient pulse anti-interference test after the test is passed, and carrying out a large current injection test, a radio frequency anti-interference test, a radiation emission test and a power line conduction emission test after the test is passed;
determining the following working states of the tested sample according to the design values of the output voltage, the output current and the output power of the tested sample:
operating state 2 a: the sample piece works in the states of maximum output voltage and minimum output current;
operating state 2 b: the sample piece works in a state of minimum output voltage and maximum output current;
operating state 2 c: the sample piece works in the states of maximum output power and maximum output current;
operating state 2 d: the sample piece works in the states of maximum output power and maximum output voltage;
operating state 2 e: the sample piece works in a state of minimum output voltage and minimum output current;
the working states of the tested sample piece during the electrostatic discharge test and the power line transient pulse anti-interference test are respectively 2a and 2 b; during the high-current injection test and the radio frequency anti-interference test, the working states of the tested sample piece are respectively 2a and 2 e; and during the radiation emission test and the power line conduction emission test, the working states of the tested sample piece are respectively 2c and 2 d.
4. The EMC self-verification method of a headlamp LED driver module of claim 3, characterized in that: in the electrostatic discharge test, for a tested sample with a metal part on a shell, the tested sample needs to be placed on an insulating pad and directly placed on a grounding steel plate or a grounding copper plate for test verification respectively; the static discharge test comprises a static electricity-off mode test and a static electricity-on mode test, and the passing standard of the static electricity-off mode test is that the function of the tested sample is normal after the static electricity-off mode test is powered on; the passing standard of the static electrification mode test is that the functions of the tested sample piece are normal during and after the test.
5. The EMC self-verification method of a headlamp LED driver module of claim 4, characterized in that: when the static electricity-off mode is tested, the voltage grades of contact discharge are +/-4 kV, +/-6 kV and +/-8 kV, when the voltage grade is +/-4 kV, the discharge point is a PIN foot, when the voltage grade is +/-8 kV, the discharge point is a shell metal part including a screw, and when the voltage grade is +/-6 kV, the discharge point is the PIN foot and the shell metal part including the screw; when the static electrification mode is tested, the voltage grades of contact discharge are +/-6 kV and +/-8 kV, and the discharge point is a shell metal part including a screw; no matter the static electricity-free mode test or the static electricity-charged mode test, the voltage grade of the air discharge test in the static discharge test is +/-8 kV and +/-15 kV, and a discharge point is the whole shell part including a gap; each voltage level in the electrostatic discharge test should be discharged 10 times, and the interval between two adjacent discharges is 3s, and each of the tests should be repeated after changing the polarity.
6. The EMC self-verification method of a headlamp LED driver module of claim 5, characterized in that: the power line of the power line transient pulse anti-interference test comprises power lines of all tested samples and all wire harnesses directly connected to the storage battery through switch control on all the tested samples, and the test comprises independent test aiming at each wire and test after all the wires are combined together;
in the power line transient pulse anti-interference test, when pulses with the amplitude of-150V are applied, the number of the applied pulses is 5000, and the passing standard of the test is that the module driving LED can flicker or extinguish in the test, but needs to automatically recover to be normal after the test; when the pulse with the amplitude of +75V is applied, the number of the applied pulses is 5000, and the standard that the module drives the LED and has no abnormal phenomenon in the test and after the test is passed; when 10V pulses are applied, the number of the applied pulses is 10, and the standard that the module drives the LED to flicker or extinguish in the test is passed, but the module needs to automatically recover to be normal after the test; when a pulse with the amplitude of-200V is applied, the time for applying the pulse is 1h, and the standard that the module drives the LED and has no abnormal phenomenon in the test and after the test is passed; when a pulse with the amplitude of +112V is applied, the pulse application time is 1h, and the standard that the module drives the LED and needs no abnormal phenomenon in the test and after the test is passed; when a pulse with the amplitude of 20.5V is applied, 10 pulses are applied every 1 minute, and the standard of passing the test is that the LED driven by the module without overvoltage protection can have jitter in the test but cannot be extinguished or flickered; the LED driven by the module with overvoltage protection can flicker in the test, but needs to be automatically restored to normal after the test.
7. The EMC self-verification method of a headlamp LED driver module of claim 6, characterized in that: when the large current is injected into the test, the negative end of the storage battery is connected with the grounding flat plate, and the storage battery is arranged on the grounding flat plate or below the test board; the length of a wire harness between the sample piece to be tested and the test auxiliary equipment is 1700mm, the wire harness is placed on an insulating pad with the thickness of 50mm of the grounding flat plate, and the relative dielectric constant epsilon r of the insulating pad is less than or equal to 1.4; the test bench should contain a ground plate, the edge of which exceeds the test device by at least 100mm in all directions; the distance between the testing device and all other conductive structures except the grounding flat plate is ensured to be more than or equal to 100 mm; the injection clamp is insulated from the grounding flat plate, and 0.03MHz is taken step by step when the tested frequency range is 0.1-1 MHz; when the tested frequency range is 1-200MHz, 1MHz is taken in a stepping mode; when the tested frequency range is 200-400MHz, stepping to take 2 MHz; when common-mode large current injection is performed, all wire harnesses output by a module need to be added into an injection clamp, the modulation modes of interference signals are CW and AM 80%, when differential-mode large current injection is performed, all wire harnesses except a ground wire need to be added into the injection clamp, the modulation modes of the interference signals are CW and AM 80%, the passing standard of the test of the large current injection test is that no abnormality exists in the test and after the test, the injection clamp needs to be respectively arranged at positions 150mm, 450mm and 750mm away from a tested sample within the frequency range of 0.1MHz-400MHz for testing, wherein the differential-mode large current injection test is performed at the positions 150mm and 450mm, and the common-mode large current injection test is performed at the positions 450mm and 750 mm; if the deviation phenomenon of the function of the tested sample is found in the test, the injection current is gradually reduced until the function of the tested sample is recovered to be normal; then, the injection current should be increased step by step until the deviation phenomenon occurs again in the function of the sample to be measured, and the injection current value is recorded as a threshold value.
8. The EMC self-verification method of a headlamp LED driver module of claim 7, characterized in that: in the radio frequency anti-interference test, for the test with the frequency less than or equal to 1000MHz, the transmitting antenna is arranged right in front of the central position of the wiring harness of the tested sample, and for the test with the frequency more than or equal to 1000MHz, the antenna is translated for 750mm along the front edge of the grounding flat plate and is opposite to the tested sample; the center of the antenna is opposite to a tested sample, the length of a wire harness is 1700mm, the tested sample and the wire harness of the test auxiliary equipment are placed in a bent mode, the bending angle of the wire harness is 90-135 degrees, and the test wire harness is placed on an insulating pad with the thickness of 50mm of a grounding flat plate; when the tested frequency range is 200-400MHz, stepping to take 2 MHz; when the tested frequency range is 400-1000MHz, 5MHz is taken in a stepping mode; when the tested frequency range is 1000-3200MHz, 10MHz is taken step by step; the residence time of all modulation modes is not less than 2s, the test polarization mode comprises a horizontal polarization mode and a vertical polarization mode, when the test frequency range is larger than or equal to 1000MHz, the tested sample is respectively tested in three axial directions, if the deviation phenomenon of the function of the tested sample is found in the test, the test field strength is gradually reduced until the function of the tested sample is recovered to be normal, then the field strength is gradually increased until the deviation phenomenon of the function of the tested sample occurs again, and the field strength value is used as a threshold value to be recorded.
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