MSPM0G3507: FULL_SCALE_CURRENT_BASE does not work as calculated.

Hello my dear supporters and engineers,

I modified several settings in ISR.C to ensure that the motor runs at the current base calculated.
However, this is limited to open loop only.
Once the closed loop is entered, the motor will not operate again. I will explain it with photos.

In the photo above, in open loop, numbers 1, 3, and 5 are the gate waveforms of the high-side mosfet of the half-bridge circuit for phases a, b, and c, and numbers 2, 4, and 6 are the output waveforms of each phase.

The photo above shows the high-side and low-side waveforms of each phase in open loop.

The picture above is the output current of each phase in open loop.

The photo above shows the high-side gate voltage waveform of each phase and the output waveform of each phase at the moment of entering the closed loop. Voltage goes below 12V.

The photo above shows the current waveforms of each phase at the point of entering the closed loop. The current cycle becomes longer. Check the horizontal axis.

I'm curious why it spins in open loop but doesn't spin in closed loop.

Hi Donguk,

donguk Lee said:

Please check this issue, and let me know if you need mor information.

We do give the insturctions in the user guide:

That is the reason why it is 7A.

You can find the hardware documents in the SDK:

C:\ti\mspm0_sdk_2_02_00_05\docs\english\middleware\motor_control_pmsm_sensorless_foc

B.R.

Sal

Hi Sal,

We need to use a 1m ohm shunt resistor. And even if it is 1m Ohm, the motor will work well if it has a current base of 7.128. The maximum current should be 30A, We believe that motor operation will be possible with 1 mOhm.

B.R.

Donguk

noise

Hi Donguk,

Sorry for the late reply. I am busy with some items.

donguk Lee said:

We need to use a 1m ohm shunt resistor.

What the motor rated current? The current base should be proper.

• This is for best ADC performance. When set the larger current base, normally means the shunt resistor is smaller. This will make the actual value of the current sampling signal has too much noise.

Maybe you can check the OPA output signal of the DRV, the current signal should be similar with below:

This is my test with DRV8329EVM before, maybe you can also check the OPA output, to see any issues here.

donguk Lee said:

The photo above shows the current waveforms of each phase at the point of entering the closed loop. The current cycle becomes longer. Check the horizontal axis.

It do have the possibility. Unproper setting will make the Observer incorrect.

What's your setting of below register:

B.R.

Sal

Hi Sal,

Is the waveform photo you uploaded correct from measuring the voltage between SO and GND of the DRV8329?

The picture posted above as noise is the voltage between So pin and GND when our protopcb operates.

The register settings are as follows:

and, The rated current is 30A.

B.R.

Donguk

The above register setting is when running in an open loop, and the motor stops in a close loop by changing closeLoopDis of algoDebugCtrl1 to 0 to enable closeloop, and it stops in MOTOR_STALL status due to faultCfg2.b.lowBemfFault.

B.R.

Donguk