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TIDA-01541: Cut-off Frequency of Motor Current Sampling Circuit

Part Number: TIDA-01541
Other Parts Discussed in Thread: AMC1301


The motor current control loop is generally equal to the switching frequency. Sometimes it can be twice the switching frequency.The switching frequency of IGBT module is generally less than 10KHz.According to Nyquist's law, in order to prevent frequency aliasing, the bandwidth of the anterior analog circuit of SAR ADC is required to be less than half of the sampling bandwidth of SAR ADC.Despite the high sampling rate of SAR ADC, for the control loop, each control cycle is sampled only once. The control period is equal to the sampling period.

In this circuit board, the bandwidth of current sampling circuit is 94 KHz, which is much larger than that of the current control loop sampling frequency . Is this design unreasonable? Or is my previous statement incorrect?