Sensored BLDC, MCX A15x vs N9x

dav1 — Mon, 10 Jun 2024 18:14:58 GMT

Ran across these two app-notes around PMSM / BLDC,

is there a reason why MCX A153 only provides an open loop / sensorless example?
https://www.nxp.com/docs/en/user-guide/PMSMFRDMMCXA153.pdf

while the MCX N947 example is closed-loop sensored:
https://www.nxp.com/docs/en/user-guide/PMSMFRDMMCXN947.pdf

Trying to iron out what the hardware limitations of the A15x series are when it comes to closed loop motor control as N5/9-series feels overkill putting the older LPC553x somewhere in the middle.

As far as I understand, both MCU's has the FlexPWM's needed, ADC to PWM XBAR, ADC's fast enough to read analog hall sensors, AOI and SINC filter, right?

also... just comparing the product-pages, could NXP shed some light on this

MCX N9x
motor Control Subsystem

2x eFlexPWM each with 4 sub-modules, providing 12 PWM outputs
2x Quadrature Encoder/Decoder (ENC)
1x Event Generator (AND/OR/INVERT) module support up to 8 output trigger
SINC Filter Module (3rd order, 5ch, break signals connections to PWM)

MCX A14x/15x
Motor Control Subsystem

1x FlexPWM with 3 submodules, providing 9 PWM outputs (no Nanoedge module)
1x Quadrature Decoder (QDC), provides interfacing capability to position/speed sensors used in industrial motor control applications
1x AOI

differences based on above:

eFlexPWM vs FlexPWM
- what is the feature-difference here?
no SINC filter on A series
- whats the use-cases of this module?
is EVTG same as AOI !?

Re: Sensored BLDC, MCX A15x vs N9x

xiangjun_rong — Tue, 11 Jun 2024 03:52:09 GMT

Hi,

Q1)is there a reason why MCX A153 only provides an open loop / sensorless example?
https://www.nxp.com/docs/en/user-guide/PMSMFRDMMCXA153.pdf

>>>>>The MCX A153 can provide both open loop and closed loop example. For BLDC/PMSM control, the rotor position is required, for sensorless solution, the rotor position is estimated based on stator current and voltage. No matter whether MCX A or N family is used, at start-up stage, the open-loop control solution is used, after start-up, the closed loop is used.

Q2)differences based on above:

eFlexPWM vs FlexPWM

- what is the feature-difference here?
- >>>>>Both N and A families use eFlexPWM, the same IP. But the N family has two eFlexPWM modules, the A family has only one eFlexPWM module. Furthermore, the eFlexPWM module of MCXA family has only 3 sub-module SM0, SM1 and SM2, while eFlexPWM module of MCXN family has 4 sub-module SM0, SM1,SM2 and SM3.
no SINC filter on A series
- whats the use-cases of this module?
- >>>>>>>Yes, the A family does not have SINC module. The SINC module is used to connect to current sensor which can output similar PDM signal in Motor control application. Currently, we use shunt resistor to sample the current of 3 branches instead of dedicated current sensor, the shunt resistor is connected to the bottom branch. Both A and N families can use the shunt resistor to sample the branch current.
- So the A family can not connect with current sensor which output PDM like signal.
- the current sensor which output PDM like signal is a new sensor technology
is EVTG same as AOI !?
>>>>>>The EVTG is the same as AOI, but the EVTG has improved, it adds several flip-flops.
Hope it can help you
BR

XiangJun Rong

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Sensored BLDC, MCX A15x vs N9x

Re: Sensored BLDC, MCX A15x vs N9x