1 Auxiliary power test
Test instruction:
The auxiliary power supply in the power supply is of great significance. The normal operation of the power module is guaranteed by the auxiliary power supply. The auxiliary power supply work is more reliable than the main circuit requirement, because even if the input voltage exceeds the limit, the auxiliary power supply should work normally to achieve The normal protection logic, and the driving of the power device, the operation of the control chip must be guaranteed by the auxiliary power supply. Therefore, the requirement for the auxiliary power supply is: stable and reliable in the case of dynamic or static conditions. The voltage is stable to meet the requirements of control and communication circuits. Pay close attention to the auxiliary power supply during the test work.
Test Methods:
Auxiliary power supply should pay attention to the following issues:
A. Is the design of the starting resistor reasonable? The design of the current limiting resistor (the input of the auxiliary power supply and the high-voltage DC busbar series in series) is reasonable;
B. In the static case, the voltage of the auxiliary power supply is within the full voltage and load;
C. In the case of large dynamics, whether the auxiliary power supply is normal;
D. Whether the output voltage is overshooted during startup, and whether the 384X Isence terminal and the drive waveform are abnormal;
E, output voltage waveform monitoring;
F. Electrical stress test of the switch tube;
G, temperature stress test of auxiliary power supply;
H, the main parameters of the work of the chip, such as operating voltage, power consumption and so on.
For these issues, you need to test the corresponding project:
A, start resistor and current limiting resistor test
The power derating of the starting resistor must meet the design requirements. The formula for calculating the power is:
P=(Bmax-V1)/R, where Vmax is the maximum input voltage of the auxiliary power supply under various conditions, V1 is the normal working voltage of the auxiliary power control chip (UC384X), and the calculated power cannot exceed the power of the selected starting resistor. At the same time, the temperature rise of the starting resistor must meet the derating requirements. Under the highest ambient temperature and the highest input voltage Vmax of the auxiliary power supply, the maximum temperature of the starting resistor (after temperature stabilization) does not exceed 120oC (15oC derating, 135oC-15oC=120oC) during normal operation, if tested at room temperature The test temperature rise needs to be switched to the highest working ambient temperature.
The power of the current limiting resistor should also meet the requirements of derating. Use the oscilloscope to test the voltage waveform at both ends of the resistor under full load and full load shutdown. Through the voltage waveform, test the effective value of the power supply at both ends of the resistor, and calculate according to the effective value. The power of the resistor requires power to meet the derating requirements during startup and shutdown as well as under normal conditions.
B, static case, output voltage range test
The input voltages of the test module are Vinmin, Vinnom, Vinmax and output Iomin, Ionom, Iomax, output current limit, output voltage of each auxiliary power supply in the depth limit current state, and each output voltage is required in each case. It is stable and can meet the reliable working requirements of the control loop and communication loop (Note: Vinmin is the voltage that the auxiliary power supply has just started to work, Vinmax is the voltage after the module input overvoltage protection, after overvoltage protection and undervoltage protection, the modules are Can work normally).
C. Dynamic conditions, the auxiliary power supply output voltage range:
Use AC SOURCE to adjust the module's input voltage and output load to jump at the same time (the input voltage jumps between the highest voltage and the lowest input voltage, the transition time is 50ms, the output jumps from no load to full load, and the jump time is 5ms. Tr and tf are set to 20us corresponding to 1A). In this case, testing the output voltage of each auxiliary power supply requires that each output voltage be stable and meet the reliable operation requirements of the control loop and communication loop.
D, key point waveform test:
Test the output voltage waveform at the input overvoltage point -5V, undervoltage point +5V start, 3844 Isence terminal and switch tube drive waveform, monitor whether output voltage overshoot, switch tube overcurrent and switch tube drive end waveform abnormality, etc. . At the same time, in various dynamic situations (including input dynamics, output dynamics), waveform testing of each key point.
E, output voltage ripple test:
In the case of output rated linear load, the output voltage waveform is tested by the test voltage ripple method, and the ripple PP value should be less than 5% of the output voltage.
Judging criteria:
The above test items are used as tests to test the performance of the auxiliary power supply. The starting resistance temperature rises normally, there is no abnormality of the switching tube current and the driving waveform, the auxiliary power supply voltage is normal in the working range, the auxiliary power supply is normal in the abnormal voltage input range (normal in the range where the power supply can achieve protection), and is qualified; otherwise it is unqualified .
2 drive circuit test
Test instruction:
The driving technology of the power device is an important guarantee for the reliability of the power supply. The good driving mode can achieve effective turn-on and turn-off, high efficiency, low EMI interference, fast realization of power device protection, etc. Test, in order to prevent the impact caused by the probe, the differential isolation probe should be used in the test (or a general probe, and the power supply of the oscilloscope is isolated by an isolation transformer), and pay attention to the following problems:
A, drive circuit analysis;
B, driving voltage;
C, drive waveform;
D. Driving waveforms under transient conditions;
F, the voltage of the driver chip, such as the chip supply voltage during the start-up process.
Test Methods:
(1) Analysis of the drive circuit
Audit drive circuit mode, regardless of transformer isolation drive and integrated IC drive, drive resistance should meet the recommended requirements, if the acceleration capacitor or fast turn-off mode should be used to evaluate its effect, the negative pressure should be confirmed when the shutdown, the general GS There should be a Zener tube, analyze the drive circuit, and confirm the rationality of the circuit design.
(2) Driving voltage
At present, most of the company's switching tubes use MOSFET or IGBT. The driving of MOSFET and IGBT is voltage mode. The high driving voltage will break through the gate and test in no-load, half-load, full-load, current-limit state. No-load full-load hopping, no-load to current-limit hopping, no-load-to-depth current-limit hopping (all load hopping conditions are: hopping time 5ms, tr and tf are 1A for 20us), no load to short circuit And the input voltage is the lowest, rated, highest, the driving waveform under the condition of the highest voltage to the lowest voltage transition (the transition time is 50ms), to ensure that the driving voltage is lower than the specified voltage, the general peak value should be less than 20V, and pay attention to the driving voltage. To satisfy the saturation drive.
(3) Driving waveform
Tested in no-load, light-load, half-load, full-load, current-limit state, no-load full-load hopping, no-load to current-limit hopping, no-load to deep current-limit hopping (all load hopping conditions are: hopping Time 5ms, tr and tf are 1A for 20us), no-load to short-circuit and input voltage is lowest, rated, highest, drive waveform from the highest voltage to the lowest voltage transition (jump time is 50ms), the waveform rises And the falling edge should be smooth, and meet the efficiency and EMI requirements (faster rise time, less open damage of the pipe, but higher voltage spike, EMI will be larger), there should be no decline in opening, no appear after shutdown Sharp-punched, dead time meets design requirements.
Compare the PWM chip output waveform and the drive waveform to confirm that the drive waveform and the PWM output waveform are consistent.
(4) Drive circuit
Power devices (MOSFET and IGBT) drive power supplies require low impedance characteristics, the drive loop area is as small as possible, the drive line is as short as possible, and the drive loop must be separated from the power loop.
(5) Waveforms in transient state
Under transient conditions, such as switching machine, output sudden load, sudden load reduction, conversion from current limit state to steady voltage state, conversion from voltage regulation to current limit state, output short circuit, short circuit start, output short circuit release The case is normal. During the process from protection to recovery, the drive is normal, the rising and falling edges of the waveform should be smooth, and should not fall in the turn-on. No sharpshoot will occur after the turn-off. The dead time meets the design requirements, and the drive waveform should not oscillate. .
judgement standard:
Compliance with the test instructions, qualified; otherwise unqualified.
(6) Test of main control chip power supply voltage
Use the oscilloscope to test the power supply voltage of the main control chip, capture the power-on process of the module, the process of shutdown, and the waveform of the power supply voltage of the chip under normal working conditions. The power supply voltage of the chip must meet the requirements of the chip data, and it is best to work on the recommended chip data. Under the operating voltage, no voltage chip can exceed the operating voltage range of the chip in any case.
3 Stress testing of power semiconductor devices
Test instruction:
Power semiconductor devices mainly include: DCDC main power tube, output rectifier diode, PFC main power tube, PFC rectifier diode, PFC exaggerated diode and so on. The correct use of these power semiconductor devices is an important guarantee for power supply reliability. In order to ensure the reasonable use of power devices, reasonable current, voltage derating and junction temperature derating should be considered. Therefore, the test should pay attention to the following aspects:
A. Meet the voltage derating requirements;
B. Meet the current derating requirements;
C, meet the temperature derating requirements
Product categories of Storage Battery, we are specialized in manufacturers from China,Storage Battery Supplier suppliers/factory, wholesale high-quality products of manufacturing, we have the perfect after-sales service and technical support. Look forward to your cooperation!
Storage Battery
Solar Battery,Storage Battery,Solar Storage Battery,Solar Energe Storage Battery
Changxing Deli Technology Co., Ltd. , https://www.delipowers.com