Hello All,

Again, I need one more help on the sensored BLDC motor.

I am developing a driver which is having max current protection 20A. The motor is driven on 12V and 24V.

The motor is 3 phase BLDC motor.

My driver gives motor speed as 1800 RPM at 24V ,1.3A without load and 900 RPM at 12V,0.9A without load.

I have checked other 2 and 3 drivers which has dedicated IC in the circuitry for BLDC motors. They are giving following speeds,

2000 RPM at 24V , 1.5A current
1100 RPM at 12V, 1.1A current

My project is to change those dedicated IC's with micro controller. I have implemented and its working fine. All functionalities are working fine.

The project is not acceptable because of speed characteristics are not matching. Other functions are OK. Just speed characters are not fine,

It would be 1000000000 times helpful for me if you all guys will help me in this issue, So that I can submit my project.

Awaiting for your reply.

 

Details very sketchy!
No drawing or motor details etc, what micro etc and method of motor rpm feedback control, using the Halls for example, or?
There is a method using the mc33039 in conjunction with the mc33035.
Max.

 

Hello MaxHeadRoom,

I am using 3 phase sensored BLDC motor with hall as a feedback signal.

The micro controller which I am using is 16 bit Renesas controller.

 

Hello All,

Again, I need one more help on the sensored BLDC motor.

I am developing a driver which is having max current protection 20A. The motor is driven on 12V and 24V.

The motor is 3 phase BLDC motor.

My driver gives motor speed as 1800 RPM at 24V ,1.3A without load and 900 RPM at 12V,0.9A without load.

I have checked other 2 and 3 drivers which has dedicated IC in the circuitry for BLDC motors. They are giving following speeds,

2000 RPM at 24V , 1.5A current
1100 RPM at 12V, 1.1A current

My project is to change those dedicated IC's with micro controller. I have implemented and its working fine. All functionalities are working fine.

The project is not acceptable because of speed characteristics are not matching. Other functions are OK. Just speed characters are not fine,

It would be 1000000000 times helpful for me if you all guys will help me in this issue, So that I can submit my project.

Awaiting for your reply.

You wrote:
speed characteristics are not fine please specify. What do you expect?
Picbuster

 

Hello Picbuster,

First of all thanks for your reply.

The others are giving greater speed. I need to match the speed. What can be done.

 

Can any one please help me with this?

 

Probably but not without your schematic.

 

Hello all,

Please find the attached schematic here.

View attachment 131725

Please find the commutation code of my drive. The code also consist of code of ADC for Throttle which is used to change the RPM.

ak=P6;
if(state==0)danticlock(&ak);



void danticlock(unsigned char *seq)
{
switch(*seq)
{
case 3:
U1=0;U2=1;U3=1;
B1=prd;B2=ducycle;B3=prd;
break;
case 2:
U1=0;U2=1;U3=1;
B1=prd;B2=prd;B3=ducycle;
break;
case 6:
U1=1;U2=0;U3=1;
B1=prd;B2=prd;B3=ducycle;
break;
case 4:
U1=1;U2=0;U3=1;
B1=ducycle;B2=prd;B3=prd;
break;
case 5:
U1=1;U2=1;U3=0;
B1=ducycle;B2=prd;B3=prd;
break;
case 1:
U1=1;U2=1;U3=0;
B1=prd;B2=ducycle;B3=prd;
break;
}
}

 

Have you written a ramp up and down test with a 0 to 100% PWM loop and not using the ADC? This will tell you if it is an ADC reading or just your commutation code.

 

Yes. The speed control is through the duty cycle of PWM.

This is my commutation code.

 

Yes. The speed control is through the duty cycle of PWM.

This is my commutation code.

Yes, I know. BUT have you run the commutation code with hard coded ramp up to 100% PWM to make sure you are running it as fast as you can, and not limiting it by the ADC reading? Just in case the ADC reading does not go to full speed.

 

Not 100% but I am running it upto 99.25%. I have seen the full speed duty and it is 99.25%.

 

Not 100% but I am running it upto 99.25%. I have seen the full speed duty and it is 99.25%.

You need to have a pull down resistor for each Mosfet or IGBT from Gate to ground. 1k or 10k will be fine.