Several technical issues have also been the subject of discussion among engineers and experts in the industry. This article will discuss the following aspects:
First, what is the most essential difference between digital power supply and analog power supply?
The essence of the so-called digital power supply is that the PWM regulation of the output current/voltage of the power supply is generated by the digital chip according to a certain digital control method and algorithm, which is the most essential feature of the digital power supply. Those who have expanded the 8-bit, 16-bit microcontroller to provide digital input and output operation interface, remote communication interface, but the PWM adjustment of the power supply depends on the power supply of the analog power modulation chip. They can only say that they have a digital power supply face, but there is no digital power supply. "core".
Second, what are the technical bottlenecks in digital power supply implementation?
At present, digital power supply still has high-speed/high-precision ADC technology problems (digital power feedback input); high-speed/high-precision power supply PID adjustment or other algorithm PWM adjustment; high-speed/high-precision PWM output problem (digital power DAC output).
Many 32-bit DSP/ARM high-speed 10-bit, 12-bit ADCs can be used as high-speed ADC for high-frequency switching power supply, but their signal input range is generally 0~3.0/3.3V, the typical analog input range of industrial sites. Positive or negative 10V but no DSP or ARM on-chip ADC can solve, only add signal conditioning circuit on the outer end. ADI and a few well-known analog device manufacturers in the product catalog, although fully compatible with high speed, high precision (16bit ~18bit), input signal range is positive and negative 5V to plus or minus 10V ADC products, but in mainland China, there are very few successful product application records, and the problems are probably only clear to the engineers who are debugging these devices.
High-precision power supply PID adjustment or PWM adjustment of other algorithms is not a problem in the current popular 32-bit DSP or ARM processor, but if you want to add high-speed two words, many software engineers may have to frown. Take TI's motion control TMS320F2812 as an example. If the switching frequency of the power supply device reaches 300KHz, the task left to the software engineer at 150MHz system frequency is to complete the ADC input data processing and power PID in 500 DSP instruction cycles. Real-time requirements such as function adjustments are the most demanding tasks. If you want to avoid the harmonics caused by the power electronics during the cycle turn-on/turn-off, the ADC samples at the middle of the device turn-on, then the counter uses the UP-DOWN mode to count the ADC samples simultaneously at the count period value. This time the software Engineers can use the DSP instruction cycle to leave only a poor 250, power PWM adjustment task is quite arduous!
If the ADC problem can be solved by high-speed, high-precision device expansion, the power supply PWM adjustment can be completed with a higher speed DSP/ARM/FPGA, then the last high-speed/high-precision PWM output problem, that is, the resolution of high-speed digital PWM. The rate problem can only be solved by the international big manufacturers that provide DSP/ARM/FPGA. In fact, the resolution of digital PWM is not a problem in the low-frequency range of the switching power supply (this is also an important reason why TI's C28XDSP can be popular in the fields of motor drive, inverter, etc.); but to the high-frequency switching power supply, or the high-precision power supply field. This problem immediately became very prominent. Why is the high-frequency, high-precision digital switching power supply still a blank in China? It is very clear that everyone will use the calculation formula of digital PWM resolution.
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