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BLDCMotor.cpp
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BLDCMotor.cpp
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#include "BLDCMotor.h"
// BLDCMotor( int pp , float R)
// - pp - pole pair number
// - R - motor phase resistance
BLDCMotor::BLDCMotor(int pp, float _R)
: FOCMotor()
{
// save pole pairs number
pole_pairs = pp;
// save phase resistance number
phase_resistance = _R;
// torque control type is voltage by default
torque_controller = TorqueControlType::voltage;
}
/**
Link the driver which controls the motor
*/
void BLDCMotor::linkDriver(BLDCDriver* _driver) {
driver = _driver;
}
// init hardware pins
void BLDCMotor::init() {
if(monitor_port) monitor_port->println(F("MOT: Init"));
// if no current sensing and the user has set the phase resistance of the motor use current limit to calculate the voltage limit
if( !current_sense && _isset(phase_resistance)) {
float new_voltage_limit = current_limit * (phase_resistance); // v_lim = current_lim / (3/2 phase resistance) - worst case
// use it if it is less then voltage_limit set by the user
voltage_limit = new_voltage_limit < voltage_limit ? new_voltage_limit : voltage_limit;
}
// sanity check for the voltage limit configuration
if(voltage_limit > driver->voltage_limit) voltage_limit = driver->voltage_limit;
// constrain voltage for sensor alignment
if(voltage_sensor_align > voltage_limit) voltage_sensor_align = voltage_limit;
// update the controller limits
if(current_sense){
// current control loop controls voltage
PID_current_q.limit = voltage_limit;
PID_current_d.limit = voltage_limit;
// velocity control loop controls current
PID_velocity.limit = current_limit;
}else if(!current_sense && _isset(phase_resistance)){
PID_velocity.limit = current_limit;
}else{
PID_velocity.limit = voltage_limit;
}
P_angle.limit = velocity_limit;
_delay(500);
// enable motor
if(monitor_port) monitor_port->println(F("MOT: Enable driver."));
enable();
_delay(500);
}
// disable motor driver
void BLDCMotor::disable()
{
// set zero to PWM
driver->setPwm(0, 0, 0);
// disable the driver
driver->disable();
// motor status update
enabled = 0;
}
// enable motor driver
void BLDCMotor::enable()
{
// enable the driver
driver->enable();
// set zero to PWM
driver->setPwm(0, 0, 0);
// motor status update
enabled = 1;
}
/**
FOC functions
*/
// FOC initialization function
int BLDCMotor::initFOC( float zero_electric_offset, Direction _sensor_direction) {
int exit_flag = 1;
// align motor if necessary
// alignment necessary for encoders!
if(_isset(zero_electric_offset)){
// abosolute zero offset provided - no need to align
zero_electric_angle = zero_electric_offset;
// set the sensor direction - default CW
sensor_direction = _sensor_direction;
}
// sensor and motor alignment - can be skipped
// by setting motor.sensor_direction and motor.zero_electric_angle
_delay(500);
if(sensor) exit_flag *= alignSensor();
else if(monitor_port) monitor_port->println(F("MOT: No sensor."));
// aligning the current sensor - can be skipped
// checks if driver phases are the same as current sense phases
// and checks the direction of measuremnt.
_delay(500);
if(exit_flag){
if(current_sense) exit_flag *= alignCurrentSense();
else if(monitor_port) monitor_port->println(F("MOT: No current sense."));
}
if(exit_flag){
if(monitor_port) monitor_port->println(F("MOT: Ready."));
}else{
if(monitor_port) monitor_port->println(F("MOT: Init FOC failed."));
disable();
}
return exit_flag;
}
// Calibarthe the motor and current sense phases
int BLDCMotor::alignCurrentSense() {
int exit_flag = 1; // success
if(monitor_port) monitor_port->println(F("MOT: Align current sense."));
// align current sense and the driver
exit_flag = current_sense->driverAlign(driver, voltage_sensor_align);
if(!exit_flag){
// error in current sense - phase either not measured or bad connection
if(monitor_port) monitor_port->println(F("MOT: Align error!"));
exit_flag = 0;
}else{
// output the alignment status flag
if(monitor_port) monitor_port->print(F("MOT: Success: "));
if(monitor_port) monitor_port->println(exit_flag);
}
return exit_flag > 0;
}
// Encoder alignment to electrical 0 angle
int BLDCMotor::alignSensor() {
int exit_flag = 1; //success
if(monitor_port) monitor_port->println(F("MOT: Align sensor."));
// if unknown natural direction
if(!_isset(sensor_direction)){
// check if sensor needs zero search
if(sensor->needsSearch()) exit_flag = absoluteZeroSearch();
// stop init if not found index
if(!exit_flag) return exit_flag;
// find natural direction
// move one electrical revolution forward
for (int i = 0; i <=500; i++ ) {
float angle = _3PI_2 + _2PI * i / 500.0;
setPhaseVoltage(voltage_sensor_align, 0, angle);
_delay(2);
}
// take and angle in the middle
float mid_angle = sensor->getAngle();
// move one electrical revolution backwards
for (int i = 500; i >=0; i-- ) {
float angle = _3PI_2 + _2PI * i / 500.0 ;
setPhaseVoltage(voltage_sensor_align, 0, angle);
_delay(2);
}
float end_angle = sensor->getAngle();
setPhaseVoltage(0, 0, 0);
_delay(200);
// determine the direction the sensor moved
if (mid_angle == end_angle) {
if(monitor_port) monitor_port->println(F("MOT: Failed to notice movement"));
return 0; // failed calibration
} else if (mid_angle < end_angle) {
if(monitor_port) monitor_port->println(F("MOT: sensor_direction==CCW"));
sensor_direction = Direction::CCW;
} else{
if(monitor_port) monitor_port->println(F("MOT: sensor_direction==CW"));
sensor_direction = Direction::CW;
}
// check pole pair number
if(monitor_port) monitor_port->print(F("MOT: PP check: "));
float moved = fabs(mid_angle - end_angle);
if( fabs(moved*pole_pairs - _2PI) > 0.5 ) { // 0.5 is arbitrary number it can be lower or higher!
if(monitor_port) monitor_port->print(F("fail - estimated pp:"));
if(monitor_port) monitor_port->println(_2PI/moved,4);
}else if(monitor_port) monitor_port->println(F("OK!"));
}else if(monitor_port) monitor_port->println(F("MOT: Skip dir calib."));
// zero electric angle not known
if(!_isset(zero_electric_angle)){
// align the electrical phases of the motor and sensor
// set angle -90(270 = 3PI/2) degrees
setPhaseVoltage(voltage_sensor_align, 0, _3PI_2);
_delay(700);
zero_electric_angle = _normalizeAngle(_electricalAngle(sensor_direction*sensor->getAngle(), pole_pairs));
_delay(20);
if(monitor_port){
monitor_port->print(F("MOT: Zero elec. angle: "));
monitor_port->println(zero_electric_angle);
}
// stop everything
setPhaseVoltage(0, 0, 0);
_delay(200);
}else if(monitor_port) monitor_port->println(F("MOT: Skip offset calib."));
return exit_flag;
}
// Encoder alignment the absolute zero angle
// - to the index
int BLDCMotor::absoluteZeroSearch() {
if(monitor_port) monitor_port->println(F("MOT: Index search..."));
// search the absolute zero with small velocity
float limit_vel = velocity_limit;
float limit_volt = voltage_limit;
velocity_limit = velocity_index_search;
voltage_limit = voltage_sensor_align;
shaft_angle = 0;
while(sensor->needsSearch() && shaft_angle < _2PI){
angleOpenloop(1.5*_2PI);
// call important for some sensors not to loose count
// not needed for the search
sensor->getAngle();
}
// disable motor
setPhaseVoltage(0, 0, 0);
// reinit the limits
velocity_limit = limit_vel;
voltage_limit = limit_volt;
// check if the zero found
if(monitor_port){
if(sensor->needsSearch()) monitor_port->println(F("MOT: Error: Not found!"));
else monitor_port->println(F("MOT: Success!"));
}
return !sensor->needsSearch();
}
// Iterative function looping FOC algorithm, setting Uq on the Motor
// The faster it can be run the better
void BLDCMotor::loopFOC() {
// if disabled do nothing
if(!enabled) return;
// if open-loop do nothing
if( controller==MotionControlType::angle_openloop || controller==MotionControlType::velocity_openloop ) return;
// shaft angle
shaft_angle = shaftAngle();
// electrical angle - need shaftAngle to be called first
electrical_angle = electricalAngle();
switch (torque_controller) {
case TorqueControlType::voltage:
// no need to do anything really
break;
case TorqueControlType::dc_current:
if(!current_sense) return;
// read overall current magnitude
current.q = current_sense->getDCCurrent(electrical_angle);
// filter the value values
current.q = LPF_current_q(current.q);
// calculate the phase voltage
voltage.q = PID_current_q(current_sp - current.q);
voltage.d = 0;
break;
case TorqueControlType::foc_current:
if(!current_sense) return;
// read dq currents
current = current_sense->getFOCCurrents(electrical_angle);
// filter values
current.q = LPF_current_q(current.q);
current.d = LPF_current_d(current.d);
// calculate the phase voltages
voltage.q = PID_current_q(current_sp - current.q);
voltage.d = PID_current_d(-current.d);
break;
default:
// no torque control selected
if(monitor_port) monitor_port->println(F("MOT: no torque control selected!"));
break;
}
// set the phase voltage - FOC heart function :)
setPhaseVoltage(voltage.q, voltage.d, electrical_angle);
}
// Iterative function running outer loop of the FOC algorithm
// Behavior of this function is determined by the motor.controller variable
// It runs either angle, velocity or torque loop
// - needs to be called iteratively it is asynchronous function
// - if target is not set it uses motor.target value
void BLDCMotor::move(float new_target) {
// if disabled do nothing
if(!enabled) return;
// downsampling (optional)
if(motion_cnt++ < motion_downsample) return;
motion_cnt = 0;
// set internal target variable
if(_isset(new_target)) target = new_target;
// get angular velocity
shaft_velocity = shaftVelocity();
switch (controller) {
case MotionControlType::torque:
if(torque_controller == TorqueControlType::voltage) // if voltage torque control
if(!_isset(phase_resistance)) voltage.q = target;
else voltage.q = target*phase_resistance;
else
current_sp = target; // if current/foc_current torque control
break;
case MotionControlType::angle:
// angle set point
shaft_angle_sp = target;
// calculate velocity set point
shaft_velocity_sp = P_angle( shaft_angle_sp - shaft_angle );
// calculate the torque command
current_sp = PID_velocity(shaft_velocity_sp - shaft_velocity); // if voltage torque control
// if torque controlled through voltage
if(torque_controller == TorqueControlType::voltage){
// use voltage if phase-resistance not provided
if(!_isset(phase_resistance)) voltage.q = current_sp;
else voltage.q = current_sp*phase_resistance;
voltage.d = 0;
}
break;
case MotionControlType::velocity:
// velocity set point
shaft_velocity_sp = target;
// calculate the torque command
current_sp = PID_velocity(shaft_velocity_sp - shaft_velocity); // if current/foc_current torque control
// if torque controlled through voltage control
if(torque_controller == TorqueControlType::voltage){
// use voltage if phase-resistance not provided
if(!_isset(phase_resistance)) voltage.q = current_sp;
else voltage.q = current_sp*phase_resistance;
voltage.d = 0;
}
break;
case MotionControlType::velocity_openloop:
// velocity control in open loop
shaft_velocity_sp = target;
voltage.q = velocityOpenloop(shaft_velocity_sp); // returns the voltage that is set to the motor
voltage.d = 0;
break;
case MotionControlType::angle_openloop:
// angle control in open loop
shaft_angle_sp = target;
voltage.q = angleOpenloop(shaft_angle_sp); // returns the voltage that is set to the motor
voltage.d = 0;
break;
}
}
// Method using FOC to set Uq and Ud to the motor at the optimal angle
// Function implementing Space Vector PWM and Sine PWM algorithms
//
// Function using sine approximation
// regular sin + cos ~300us (no memory usaage)
// approx _sin + _cos ~110us (400Byte ~ 20% of memory)
void BLDCMotor::setPhaseVoltage(float Uq, float Ud, float angle_el) {
float center;
int sector;
float _ca,_sa;
switch (foc_modulation)
{
case FOCModulationType::Trapezoid_120 :
// see https://www.youtube.com/watch?v=InzXA7mWBWE Slide 5
static int trap_120_map[6][3] = {
{_HIGH_IMPEDANCE,1,-1},{-1,1,_HIGH_IMPEDANCE},{-1,_HIGH_IMPEDANCE,1},{_HIGH_IMPEDANCE,-1,1},{1,-1,_HIGH_IMPEDANCE},{1,_HIGH_IMPEDANCE,-1} // each is 60 degrees with values for 3 phases of 1=positive -1=negative 0=high-z
};
// static int trap_120_state = 0;
sector = 6 * (_normalizeAngle(angle_el + _PI_6 ) / _2PI); // adding PI/6 to align with other modes
// centering the voltages around either
// modulation_centered == true > driver.volage_limit/2
// modulation_centered == false > or Adaptable centering, all phases drawn to 0 when Uq=0
center = modulation_centered ? (driver->voltage_limit)/2 : Uq;
if(trap_120_map[sector][0] == _HIGH_IMPEDANCE){
Ua= center;
Ub = trap_120_map[sector][1] * Uq + center;
Uc = trap_120_map[sector][2] * Uq + center;
driver->setPhaseState(_HIGH_IMPEDANCE, _ACTIVE, _ACTIVE); // disable phase if possible
}else if(trap_120_map[sector][1] == _HIGH_IMPEDANCE){
Ua = trap_120_map[sector][0] * Uq + center;
Ub = center;
Uc = trap_120_map[sector][2] * Uq + center;
driver->setPhaseState(_ACTIVE, _HIGH_IMPEDANCE, _ACTIVE);// disable phase if possible
}else{
Ua = trap_120_map[sector][0] * Uq + center;
Ub = trap_120_map[sector][1] * Uq + center;
Uc = center;
driver->setPhaseState(_ACTIVE,_ACTIVE, _HIGH_IMPEDANCE);// disable phase if possible
}
break;
case FOCModulationType::Trapezoid_150 :
// see https://www.youtube.com/watch?v=InzXA7mWBWE Slide 8
static int trap_150_map[12][3] = {
{_HIGH_IMPEDANCE,1,-1},{-1,1,-1},{-1,1,_HIGH_IMPEDANCE},{-1,1,1},{-1,_HIGH_IMPEDANCE,1},{-1,-1,1},{_HIGH_IMPEDANCE,-1,1},{1,-1,1},{1,-1,_HIGH_IMPEDANCE},{1,-1,-1},{1,_HIGH_IMPEDANCE,-1},{1,1,-1} // each is 30 degrees with values for 3 phases of 1=positive -1=negative 0=high-z
};
// static int trap_150_state = 0;
sector = 12 * (_normalizeAngle(angle_el + _PI_6 ) / _2PI); // adding PI/6 to align with other modes
// centering the voltages around either
// modulation_centered == true > driver.volage_limit/2
// modulation_centered == false > or Adaptable centering, all phases drawn to 0 when Uq=0
center = modulation_centered ? (driver->voltage_limit)/2 : Uq;
if(trap_150_map[sector][0] == _HIGH_IMPEDANCE){
Ua= center;
Ub = trap_150_map[sector][1] * Uq + center;
Uc = trap_150_map[sector][2] * Uq + center;
driver->setPhaseState(_HIGH_IMPEDANCE, _ACTIVE, _ACTIVE); // disable phase if possible
}else if(trap_150_map[sector][1] == _HIGH_IMPEDANCE){
Ua = trap_150_map[sector][0] * Uq + center;
Ub = center;
Uc = trap_150_map[sector][2] * Uq + center;
driver->setPhaseState(_ACTIVE, _HIGH_IMPEDANCE, _ACTIVE);// disable phase if possible
}else{
Ua = trap_150_map[sector][0] * Uq + center;
Ub = trap_150_map[sector][1] * Uq + center;
Uc = center;
driver->setPhaseState(_ACTIVE, _ACTIVE, _HIGH_IMPEDANCE);// disable phase if possible
}
break;
case FOCModulationType::SinePWM :
// Sinusoidal PWM modulation
// Inverse Park + Clarke transformation
// angle normalization in between 0 and 2pi
// only necessary if using _sin and _cos - approximation functions
angle_el = _normalizeAngle(angle_el);
_ca = _cos(angle_el);
_sa = _sin(angle_el);
// Inverse park transform
Ualpha = _ca * Ud - _sa * Uq; // -sin(angle) * Uq;
Ubeta = _sa * Ud + _ca * Uq; // cos(angle) * Uq;
// center = modulation_centered ? (driver->voltage_limit)/2 : Uq;
center = driver->voltage_limit/2;
// Clarke transform
Ua = Ualpha + center;
Ub = -0.5 * Ualpha + _SQRT3_2 * Ubeta + center;
Uc = -0.5 * Ualpha - _SQRT3_2 * Ubeta + center;
if (!modulation_centered) {
float Umin = min(Ua, min(Ub, Uc));
Ua -= Umin;
Ub -= Umin;
Uc -= Umin;
}
break;
case FOCModulationType::SpaceVectorPWM :
// Nice video explaining the SpaceVectorModulation (SVPWM) algorithm
// https://www.youtube.com/watch?v=QMSWUMEAejg
// the algorithm goes
// 1) Ualpha, Ubeta
// 2) Uout = sqrt(Ualpha^2 + Ubeta^2)
// 3) angle_el = atan2(Ubeta, Ualpha)
//
// equivalent to 2) because the magnitude does not change is:
// Uout = sqrt(Ud^2 + Uq^2)
// equivalent to 3) is
// angle_el = angle_el + atan2(Uq,Ud)
float Uout;
// a bit of optitmisation
if(Ud){ // only if Ud and Uq set
// _sqrt is an approx of sqrt (3-4% error)
Uout = _sqrt(Ud*Ud + Uq*Uq) / driver->voltage_limit;
// angle normalisation in between 0 and 2pi
// only necessary if using _sin and _cos - approximation functions
angle_el = _normalizeAngle(angle_el + atan2(Uq, Ud));
}else{// only Uq available - no need for atan2 and sqrt
Uout = Uq / driver->voltage_limit;
// angle normalisation in between 0 and 2pi
// only necessary if using _sin and _cos - approximation functions
angle_el = _normalizeAngle(angle_el + _PI_2);
}
// find the sector we are in currently
sector = floor(angle_el / _PI_3) + 1;
// calculate the duty cycles
float T1 = _SQRT3*_sin(sector*_PI_3 - angle_el) * Uout;
float T2 = _SQRT3*_sin(angle_el - (sector-1.0)*_PI_3) * Uout;
// two versions possible
float T0 = 0; // pulled to 0 - better for low power supply voltage
if (modulation_centered) {
T0 = 1 - T1 - T2; //modulation_centered around driver->voltage_limit/2
}
// calculate the duty cycles(times)
float Ta,Tb,Tc;
switch(sector){
case 1:
Ta = T1 + T2 + T0/2;
Tb = T2 + T0/2;
Tc = T0/2;
break;
case 2:
Ta = T1 + T0/2;
Tb = T1 + T2 + T0/2;
Tc = T0/2;
break;
case 3:
Ta = T0/2;
Tb = T1 + T2 + T0/2;
Tc = T2 + T0/2;
break;
case 4:
Ta = T0/2;
Tb = T1+ T0/2;
Tc = T1 + T2 + T0/2;
break;
case 5:
Ta = T2 + T0/2;
Tb = T0/2;
Tc = T1 + T2 + T0/2;
break;
case 6:
Ta = T1 + T2 + T0/2;
Tb = T0/2;
Tc = T1 + T0/2;
break;
default:
// possible error state
Ta = 0;
Tb = 0;
Tc = 0;
}
// calculate the phase voltages and center
Ua = Ta*driver->voltage_limit;
Ub = Tb*driver->voltage_limit;
Uc = Tc*driver->voltage_limit;
break;
}
// set the voltages in driver
driver->setPwm(Ua, Ub, Uc);
}
// Function (iterative) generating open loop movement for target velocity
// - target_velocity - rad/s
// it uses voltage_limit variable
float BLDCMotor::velocityOpenloop(float target_velocity){
// get current timestamp
unsigned long now_us = _micros();
// calculate the sample time from last call
float Ts = (now_us - open_loop_timestamp) * 1e-6;
// quick fix for strange cases (micros overflow + timestamp not defined)
if(Ts <= 0 || Ts > 0.5) Ts = 1e-3;
// calculate the necessary angle to achieve target velocity
shaft_angle = _normalizeAngle(shaft_angle + target_velocity*Ts);
// for display purposes
shaft_velocity = target_velocity;
// use voltage limit or current limit
float Uq = voltage_limit;
if(_isset(phase_resistance)) Uq = current_limit*phase_resistance;
// set the maximal allowed voltage (voltage_limit) with the necessary angle
setPhaseVoltage(Uq, 0, _electricalAngle(shaft_angle, pole_pairs));
// save timestamp for next call
open_loop_timestamp = now_us;
return Uq;
}
// Function (iterative) generating open loop movement towards the target angle
// - target_angle - rad
// it uses voltage_limit and velocity_limit variables
float BLDCMotor::angleOpenloop(float target_angle){
// get current timestamp
unsigned long now_us = _micros();
// calculate the sample time from last call
float Ts = (now_us - open_loop_timestamp) * 1e-6;
// quick fix for strange cases (micros overflow + timestamp not defined)
if(Ts <= 0 || Ts > 0.5) Ts = 1e-3;
// calculate the necessary angle to move from current position towards target angle
// with maximal velocity (velocity_limit)
if(abs( target_angle - shaft_angle ) > abs(velocity_limit*Ts)){
shaft_angle += _sign(target_angle - shaft_angle) * abs( velocity_limit )*Ts;
shaft_velocity = velocity_limit;
}else{
shaft_angle = target_angle;
shaft_velocity = 0;
}
// use voltage limit or current limit
float Uq = voltage_limit;
if(_isset(phase_resistance)) Uq = current_limit*phase_resistance;
// set the maximal allowed voltage (voltage_limit) with the necessary angle
setPhaseVoltage(Uq, 0, _electricalAngle(shaft_angle, pole_pairs));
// save timestamp for next call
open_loop_timestamp = now_us;
return Uq;
}