can FOC Frequency be very low?

[Lzhiy.1]

I've designed an FOC board.First of all,I want to realize the SVPWM without using other transformation in order to make the motor rotate first.

PWMC_SetPhaseVoltage(pwmcHandle, Valphabeta);

so I generate an array about Valphabeta as the code below:

#define PIDIV180 0.017453292519943
#define MAX 25000
int main()
{
    double cnt=0,angle;
    int a,b;
    printf("int16_t test1[][2]=\n{\n");
    for(cnt = 0;cnt<90;cnt+=0.05)
    {
        angle = cnt * PIDIV180;
        a = MAX*cos(angle);
        b = MAX*sin(angle);
        printf("{%d,%d},\n",a,b);
    }
    printf("};");
    return 0;
}

and the FOC code is changed to below:

	cnt = (cnt+1)%1800;
	if(!cnt)
	{
		cnt1 = (cnt1+1)%4;
	}
	
	switch(cnt1)
	{
		case 0:// 4 quadrand
			a = test1[cnt][0];
			b = test1[cnt][1];
			break;
		case 1:// 3 quadrand
			a = -test1[cnt][1];
			b = test1[cnt][0];
			break;
		case 2:// 2 quadrand
			a = -test1[cnt][0];
			b = -test1[cnt][1];
			break;
		case 3:// 1 quadrand
			a = test1[cnt][1];
			b = -test1[cnt][0];
			break;
	}
 
	Valphabeta.alpha = a;
	Valphabeta.beta = b;
        hCodeError = PWMC_SetPhaseVoltage(pwmcHandle, Valphabeta);

when PWM_FREQUENCY is above 10k,the motor rotates,but when PWM_FREQUENCY is slow like 5k,the motor rotates back and forth at a small angle.

Where is the problem?FOC frequency can't be too low or my test method is wrong.

[Saurabh SONA]

The X-CUBE-MCSDK standard code works well at frequencies lower than 10kHz. The lowest supported PWM frequency is in fact 2kHz. The optimal PWM frequency depends on the motor parameters.

[Lzhiy.1 · Accepted solution]

Solved.It depends on the ADV_TIM_CLK_MHz.

#define ADV_TIM_CLK_MHz   128
#define PWM_FREQUENCY     5000
#define PWM_PERIOD_CYCLES (uint16_t)((ADV_TIM_CLK_MHz*(uint32_t)1000000u/((uint32_t)(PWM_FREQUENCY)))&0xFFFE)
 
and the variable:
    .hT_Sqrt3 = (PWM_PERIOD_CYCLES*SQRT3FACTOR)/16384u,
is out of bound.