Switching power supply digital oscilloscope measurement method
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 working environments. Equipment load and demand may undergo significant changes in an instant. Even "daily" switch mode power supplies must be able to withstand instantaneous peak values far exceeding their 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 difficult calculations with 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 setup and making dynamic measurements easier. Users can customize key parameters, automatically calculate, and see results in seconds, not just raw data.
Power supply design issues and their measurement requirements
In an ideal situation, each power supply should work like the mathematical model designed for it. But in the real world, components are defective, loads can change, power supplies may become 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 deal with 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 occupy less space, reduce heat, lower manufacturing costs, and meet stricter EMI/EMC standards. Only a strict measurement system can enable engineers to achieve these goals.
Oscilloscope and power measurement
For those accustomed to using oscilloscopes for high bandwidth measurements, power measurement may be simple due to its relatively low frequency. 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 vary. It is necessary to accurately capture and analyze the waveform, and detect any anomalies in the waveform. The requirements for this oscilloscope are strict. Multiple probes - requiring single ended probes, differential probes, and current probes simultaneously. 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 one acquisition.
