# Search results

1. ### Where could I buy a permanent magnet BLDC in 10 ~ 20HP??

In urgent need. Please help! Thx a lot!
2. ### How to have Valpha and Vbeta from line-to-line voltage Vab and Vbc?

I need to do the vector control on the motor and what I can have is just line-to-line voltage Vab, Vbc and Vca. How could I calculate quadrature axis voltage components Vlapha and Vbeta then?? (Existed formula are from phase voltage to Valpha and Vbeta)
3. ### How to have the neutral point from three phase motor terminals?

I got it. Also, my ph-ph stator voltage is 220Vrms(311Vpeak), so I use 200K Ohm wye resistor with 1/2W. Such design is ok?? So, the less resistor curr., the better? Or any other thing should be paid attention in selecting wye resistor? Thx a lot!
4. ### How to have the neutral point from three phase motor terminals?

My motor has general 3 phase stator terminals, but I want to measure the phase-to-neutral voltage (for some control purpose). How can I have the neutral point to do the measurement then?? Pls help!! Thx a lot!
5. ### How to align the quadrature encoder for induction motor drive?

I'm using quadrature encoder to feeback rotor position and how to do the alignment between zero position of rotor and rotor flux (rotor phase A)? And then how to align this position with stator phase A then? As you might know, this is actually two alignment bet. 3 things... Thx a lot!!
6. ### How to add delay time for motor(inverter) start?

With dc voltage present, my PWM signals cannot be given to the inverter. I guess this is buz my initial PWMs are inducing a over current so the inverter turn them off. So, I have to run the PWM 1st and then turn on the dc. So, my solution is to add a delay to dc voltage inside of code. My...
7. ### Question on induction motor

Thank you, FvM and emontllo ! I think I got it...
8. ### Question on induction motor

constant magnetic field?? Then the rotor speed is reducing as well??
9. ### Question on induction motor

The IM I have is a "wound rotor IM", whose rotor terminals are accessible (just like 3 stator terminals, so I have 6 terminals)... Suppose I use another motor to drive this wound rotor IM rotating and meantime feed three ROTOR terminals by 3ph sinusoidal voltages(synchronous w. rotor position)...
10. ### how to reduce code excution time (make the code more efficiet)??

I cannot agree w. you anymore! My code is for motor drive space vector modulation (SVM) and require the magnitude of space ref. vector Vsp = sqrt(Valpha^2 + Vbeta^2). As to sin and cos, I'm using buildt-in _Q16sin() and _Q16cos() functions so does not consume much time actually...
11. ### how to reduce code excution time (make the code more efficiet)??

Thx and I tried level-1 and -2 for optimization... It seems a little improvement but not much... thx all the same...
12. ### how to reduce code excution time (make the code more efficiet)??

Thanks, Alex and horace! But WHERE to change the optimization option?? I mean, from which menu in IDE??
13. ### how to reduce code excution time (make the code more efficiet)??

I'm using dsPIC33 and just increase PLLFDB register from 45 to 58. The time excution does reduce by around 35usec!!! Thx a lot!!! As to the better complier, I am currently useing C30, and have no clue about better one. Any suggestions?? Also, since I modify the PLLFDB in the code, do I need to...
14. ### how to reduce code excution time (make the code more efficiet)??

I wrote the code in c fixed point Q16 format, and cost 120usec to excute the algorithm. Wanna reduce it to around 50usec. Any suggestions?? I have applied the built-in _Q16() functions for multiplication, power, sin, cos etc., but still too much time spent...
15. ### How to involve the assembly code/routine into my c code??

I know nothing about assembly code, so here is what I'm doing: I have a assembly rouine for atan(), how to make it work for my following c code: #include "p33fj64gs610" #include <math.h> ... int main() {... x=4; y=5; ang = atan(x,y); ... } Attaching assembly code here: ; constant...
16. ### Ask for Space Vector Modulation C routine

For motor control, I'm writing C code to implement SVM. Could someone suggest a routine in C?? (Form Valpha, Vbeta to PDCx) I can get bunch of SVM routine in assembly code but no C code yet... Thx a lot!
17. ### How to convert (-3.3 to 3.3VDC) to (0 to 3VDC) ?? i.e. voltage shifter

I have a AC voltage to be feedback to ADC of controller. So how can I shift the voltage level to the 0~3.3VDC then?? I tried a two op-amp(LM301) circ. but not working well... Could anyone help me out? Thx alot!
18. ### Quadrature encoder code question

After init etc., I calculate the speed in following way. Could someone help me find anything wrong here?? Buz the measured result varies time by time(when running the motor at constant speed). while(1) { if(TMR3<23000) { if(POS1CNT=0) {CntsRev=0; CntsRev+=1;}...
19. ### How much is the input impedance of Micorchip dsPIC33 chip ??

Thanks alot, guru and btbass! I gonna go ahead top try...
20. ### How much is the input impedance of Micorchip dsPIC33 chip ??

Let me put it specifically: My encoder signal is 0 - 5VDC pulses, as u know, and I just use a voltage divider (400Ohm & 600Ohm) to shift it down to 0 -3VDC. I havn't tried this yet, but I'm concerning about the impedance issue. That is, is my impedance of "encoder + voltage divider" much smaller...