The method of measuring switching power supply with digital oscilloscope
From traditional analog power supplies to efficient switching power supplies, the types and sizes of power supplies vary greatly. They all have to face complex and dynamic work environments. The device load and demand may undergo significant changes in an instant. Even a "daily" switching power supply must be able to withstand instantaneous peaks far exceeding its average operating level. Engineers who design power supplies or systems to use power supplies need to understand the working conditions of the power supply under static and worst-case conditions.
In the past, describing the behavioral characteristics of a power supply meant using a digital multimeter to measure static current and voltage, and performing arduous calculations using a calculator or PC. Today, most engineers turn to oscilloscopes as their preferred power measurement platform. Modern oscilloscopes can be equipped with integrated power measurement and analysis software, simplifying settings and making dynamic measurements easier. Users can customize key parameters, automatically calculate, and see results within seconds, rather than just raw data.
Power supply design issues and measurement requirements
In an ideal situation, each power supply should work like the mathematical model designed for it. But in the real world, components have defects, loads can change, power supply may be distorted, and environmental changes can alter performance. Moreover, constantly changing performance and cost requirements make power supply design more complex. Consider these issues:
How many watts of power can the power supply maintain beyond its rated power? How long can it last? How much heat does the power supply emit? What happens when it overheats? How much cooling airflow does it require? What happens when the load current increases significantly? Can the device maintain its rated output voltage? How does the power supply respond to a complete short circuit at the output end? What happens when the input voltage of the power supply changes?
Designers need to develop power supplies that take up less space, reduce heat, reduce manufacturing costs, and meet stricter EMI/EMC standards. Only a strict measurement system can enable engineers to achieve these goals.
Oscilloscope and power supply measurement
For those accustomed to using an oscilloscope for high bandwidth measurements, power measurement may be simple because its frequency is relatively low. In fact, there are many challenges in power measurement that high-speed circuit designers never have to face.
The voltage of the entire switchgear may be high and floating, meaning it is not grounded. The pulse width, period, frequency, and duty cycle of the signal will all vary. It is necessary to accurately capture and analyze the waveform, and discover any abnormalities in the waveform. The requirements for this oscilloscope are strict. Multiple probes - simultaneously requiring single ended probes, differential probes, and current probes. The instrument must have a large memory to provide recording space for long-term low-frequency acquisition results. And it may require capturing different signals with significantly different amplitudes in a single acquisition.
