Part Number: TMS320F28379D
Other Parts Discussed in Thread: DRV8412, DRV8962, TMS320F28035
Hi, I read TI document "A faster current loop pays off in servo motor control" (swpy031) and sway019.pdf, in the later document it states that:
For instance, designers of motor control applications have for years placed limitations on the current loop bandwidth because they assumed that the controller could update the PWM only once every cycle of the control loop. Now, with an integrated high-performance successive approximation register (SAR) ADC, ADC post-processing hardware, trigonometric math instructions, and other cycles avenging resources, C2000 MCUs can sample motor currents, convert them to digital data, process the data and update the PWM generator in less than 1µs. (Figure 1.) The field-oriented control (FOC) processing and PWM update takes less than 500ns.
I am little bit puzzled about this statement,
1, for example I want to use FCL (TMS320F2837xD) with DRV8412 (integrated FET driver), the maximum PWM frequency of DRV8412 is 500KHz, which is 2us. Does it mean that by using FCL or other function, we can overdrive the PWM frequency to 1MHz (1us)? And the 500 ns update interval means that we can calculate and generate a dedicated pulse width (>minimum pulse width) every 500 ns, 2MHz?
2, We need precise and smooth control for voice coil motors, so the update interval or the PWM frequency of this current loop is the higher the better, preferably 1MHz. This cycle-by-cycle current control is very attractive. If, for example, we fixed the motor driver to DRV8412 (500KHz) or more recently DRV8962 (200KHz), which C2000 chip should we choose? We found that DRV8412-C2-Kit is using TMS320F28035, and we would like to know if TMS320F2837xD or other C2000 is better.
Best,
Benyuan
