SIGLENT : The Testing and Analysis of Switching Power Supplies

SIGLENT : The Testing and Analysis of Switching Power Supplies

Power’s Key Indices

1) Output voltage, Power factor, Efficiency

Experimental objective:

To make certaina product’s output voltage,power factor and efficiency are all within specified range

Experimental environment:

25℃ room temperature or specified ambient temperature

Experimental equipment:

(1) AC power source (2) E load (3) oscilloscope

Experimental condition:

(1) When the input voltage is 90V,220V, and 264V, the output voltage is tested under a full load and no load conditions.

(2) When input voltage is 90V,220V or 264V,the output power factor is tested under a full load and no load conditions.

(3) When input voltage is 90V,220V or 264V,the output efficiency is tested under a full load and no load conditions.

(4) We can use the Power Analysis option module of an oscilloscope to test power factor and efficiency without a separate power analyzer.

2) Standby Power

Experimental objective:

To test a product’s standby power levels to make certain it meets product’s specified requirements.

Experimental environment:

25℃ room temperature or specified ambient temperature.

Experimental equipment:

(1) AC power source (2) Oscilloscope

Experiment condition:

(1) Input voltage: rated input voltage range(Test point: 90V/60HZ、115V/60HZ、132V/50HZ、180V/50HZ、230V/50HZ、240V/50HZ、264V/50HZ）

(2) Output load:no-load or load supplied by output connection to real-life value load.

(3) Use oscilloscope to test standby power levels (standby power is 1.02 W).

3) Input Surge Current:

Experimental objective:

To make certain that alternating instantaneous peak currentis within the specified range when product under test is connected to the load.

Experimental environment:

25℃ room temperature or specified ambient temperature

Experimental equipment:

(1) AC power source (2) current probe (3) high voltage differential probe (4) Oscilloscope (5) E-load

Experimental conditions and requirements:

(1) Set electronic load to full load for the product under test.

(2) Set AC power source’s phase is 90 and amplitude in specified range

(3) Experimental requirement: Peak surge current (The peak current of surge is 50 times smaller than the rated input current value, Tr<20mS; I^2t should be smaller than fuse’s rated value to meet product’s design requirement.)

4) Output Voltage Order

Experimental objective:

Test the order and difference of different groups of power’s rising time to make sure meet design requirement.

Experimental environment:

25℃ room temperature or specified ambient temperature

Experimental equipment:

(1) AC source (2) E load (3) oscilloscope

Experimental condition:

(1) Make certain the input voltage is withinthe rated voltage range

(2) Make certain the output load is within the rated load range.

5) The Rise and Fall Times of Output Voltage

Experimental objective:

Make sure that the rise time and fall time tests fall within our design requirements.

Notes:

(1) Rise time: The time required for the signal to rise from 10% to 90% of its steady-state value.

(2) Fall time: the time required for signal to fall from 90% to 10% of the peak voltage when DC poweris turned off.

Experimental environment:

25℃ room temperature or specified ambient temperature

Experimental equipment:

(1) AC power source(2) E load (3) oscilloscope

Experimental condition and requirement:

(1) Make certain the input voltage is within rated voltage range

(2) Make certain the output load is within the full-load rated range.

(3) Rise time≤100mS,fall time≤100mS;or meets product specification.

6) Overshoot Voltage

Experimental objective:

To make certain the product’s output voltage will not exceed the maximum rated voltage value when the unit is powered up or down.

Experimental environment:

25℃ room temperature or specified ambient temperature

Experimental equipment:

(1) AC source (2) E load(3) oscilloscope

Experimental condition and requirement:

(1) Makecertain the input voltage is within the specified input voltage range.

(2) Make certain the output load is within thespecified rated load range.

(3) Make certainthe outputovershoot voltage range is less than the value of maximum output voltage specification.

7) Hold Time of the Power Supply

Experimental objective:

Make certain that hold time of the power supply meets the design requirement when DC poweris shut down.

Experimental environment:

25℃ room temperature or specified ambient temperature

Experimental equipment:

(1) AC source (2) E load (3) oscilloscope

Experimental condition and requirement:

(1) Make certain that the input voltage is within rated voltage range.

(2) Make certain that the output load is within the specified rated load range.

(3) Make certain that the hold time of power supply: A- level≥20mS;B- level≥15mS;C- level≥10mS; D- level≥5ms;or meets to the design standard.

8) Slow Rise Time & Fall Time on the Input Power and Their Effect on the Circuit

Experimental objective:

To test product’s response when the input voltage rises and descends with fixed time and slope.

Experimental environment:

25℃ room temperature or specified ambient temperature

Experimental equipment:

(1) AC source (2) E load (3) oscilloscope

Experimental condition and requirement:

(1) Make certain that the input voltage is within rated voltage range.

(2) Make certain that the output load is within the specified rated load range.

(3) Make use of an AC source to control input voltage descending slowly from maximum rated values to minimum rated values in specified period of time, then rises slowly to a maximum rated value in the same specified time.The product should not experience any sort of lock-up or overload.

9) Turn-on Delay Time

Experimental objective:

Make certain that the time period between product turn-on to various output voltage values meets design requirements.

Experimental environment:

25℃ room temperature or specified ambient temperature

Experimental equipment:

(1) AC source (2) E load (3) oscilloscope

Experimental condition and requirement:

(1) Make certain that the input voltage is within rated voltage range.

(2) Make certain that the output load is within specified rated load range.

(3) Make certain that turn-on delay time ≤1s or meets the design specification/requirements.

10) Line Regulation

Experimental objective:

To make certain that the stability of various output voltage settings meet specifiedrequirement when the output voltage change is caused by a change in input voltage.

Experimental environment:

25℃ room temperature or specified ambient temperature

Experimental equipment:

(1) AC source (2) E load (3) oscilloscope

Experimental methods and requirements:

(1) Set electronic load to achieve rated power.

(2) Adjust the AC source to the maximum output voltage rating for the unit under test. Make a note of this AC voltage value and label it U1.

(3) Adjust the AC source to a value that is the nominal rated value for input voltage for the unit under test. Make a note of this value and label it U0.

(4) Adjust the AC source to a value that is the minimum output voltage rating for the unit under test. Make a note of this voltage and label it U2.

(5) Calculate as following formula: [(U-U0)/U0]×100%

Note: The U of this formula isthe absolute larger value between U1 and U2.We usually make line regulation≤5% or use our product design specifications.

11) Load Regulation

Experimental objective:

To make certainthe stability of the output voltage meets the specifications when the output load changes value.

Experimental environment:

25℃ room temperature or specified ambient temperature

Experimental equipment:

(1) AC source (2) E load (3) oscilloscope

Experimental methods and requirements:input

(1) Adjust the input voltage for its rated value and output current is zero(no-load), make a note of the output voltage and label this U1.

(2) Adjust the input voltage for its rated value and the output current is 50% of rated fully-load value, make a note of the output and label this U0.

(3) Adjust the input voltage for its rated value and the output current for full rated current about (full load). Make a note of the output voltage level and label it U2. Make a note of the output voltage and label this U2.

(4) It can be assumed that Load Regulation should be less than 5%, or refer to the product’s design specifications.

(5) Calculate load regulation as following formula: [(U-U0)/U0]×100%

Notes: The value for U in this formula is a value that changes by a large amount as compared with U1 and U2. To protect the life of the power supply under test, we typically set the output current to 50% of rated fully-load (or less), therefore, we will use output voltage as reference as this time.

12) Cross Load Regulation

Definition:

Cross Load Regulation: Refers to the output load regulation of other channels of our device under test when one of the other channels (in a multi-output supply) experiences a change in its load.

Environment conditions:

25℃ room temperature or specified ambient temperature

Experimental equipment:

(1) AC source (2) E load (3) oscilloscope

Experimental methods and requirements:

(1) The input voltage is set for the rated voltage value

(2) The power supply under test has two or more output channels, we test voltage stability’s change when the load of V1 changes.

(3) We designate V2’s voltage as U0,when V1 and V2 are both 50% of fully-loaded rating.

(4) We designate V2’s voltage as U1, when V1 and V2 re both 50% of fully loaded rating and U1 changes in value to no-load.

(5) We designate V2’s voltage as U2, when V1 and V2 re both 50% of fully loaded rating and U1 changes in value to full-load.

(6) It can be assumed that Cross Load Regulation should be less than 5%, or refer to the product’s design specifications.

(7) Calculate cross load regulation as following formula: [(U-U0)/U0]×100%

Notes:The U of this formula is a value that can vary widely compared with U1 and U2.