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[MCPWM_FOC] Eliminate repeated divisions 

`/((2.0/3.0) * v_bus)` is the same as `* 1.5/V_bus`. Abstracting this out
saves at least one division per loop, and in some cases as many as three.

Each STM32F4 FPU division takes 14 cycles.
This commit is contained in:
Kenn Sebesta 2021-11-07 07:35:08 -05:00
parent 258ad28566
commit 6dbea7ed86
1 changed files with 21 additions and 12 deletions
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33
mcpwm_foc.c
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@ -2990,8 +2990,11 @@ void mcpwm_foc_adc_int_handler(void *p, uint32_t flags) {
}
// Update corresponding modulation
motor_now->m_motor_state.mod_d = motor_now->m_motor_state.vd / ((2.0 / 3.0) * motor_now->m_motor_state.v_bus);
motor_now->m_motor_state.mod_q = motor_now->m_motor_state.vq / ((2.0 / 3.0) * motor_now->m_motor_state.v_bus);
/* voltageNormalize = 1/(2/3*V_bus) */
const float voltageNormalize = 1.5 / motor_now->m_motor_state.v_bus;
motor_now->m_motor_state.mod_d = motor_now->m_motor_state.vd * voltageNormalize;
motor_now->m_motor_state.mod_q = motor_now->m_motor_state.vq * voltageNormalize;
}
// Calculate duty cycle
@ -3791,10 +3794,13 @@ static void control_current(volatile motor_all_state_t *motor, float dt) {
utils_saturate_vector_2d((float*)&state_m->vd, (float*)&state_m->vq, max_v_mag);
// mod_d and mod_q are normalized such that 1 corresponds to the max possible voltage. This includes overmodulation and therefore cannot be made in any direction.
// Note that this scaling is different than max_v_mag, which is without over modulation.
state_m->mod_d = state_m->vd / ((2.0 / 3.0) * state_m->v_bus);
state_m->mod_q = state_m->vq / ((2.0 / 3.0) * state_m->v_bus);
// mod_d and mod_q are normalized such that 1 corresponds to the max possible voltage:
// voltageNormalize = 1/(2/3*V_bus)
// This includes overmodulation and therefore cannot be made in any direction.
// Note that this scaling is different from max_v_mag, which is without over modulation.
const float voltageNormalize = 1.5 / state_m->v_bus;
state_m->mod_d = state_m->vd * voltageNormalize;
state_m->mod_q = state_m->vq * voltageNormalize;
// TODO: Have a look at this?
#ifdef HW_HAS_INPUT_CURRENT_SENSOR
@ -3851,14 +3857,14 @@ static void control_current(volatile motor_all_state_t *motor, float dt) {
motor->m_hfi.ready = true;
}
mod_alpha_tmp += hfi_voltage * utils_tab_sin_32_1[motor->m_hfi.ind * motor->m_hfi.table_fact] / ((2.0 / 3.0) * state_m->v_bus);
mod_beta_tmp -= hfi_voltage * utils_tab_cos_32_1[motor->m_hfi.ind * motor->m_hfi.table_fact] / ((2.0 / 3.0) * state_m->v_bus);
mod_alpha_tmp += hfi_voltage * utils_tab_sin_32_1[motor->m_hfi.ind * motor->m_hfi.table_fact] * voltageNormalize;
mod_beta_tmp -= hfi_voltage * utils_tab_cos_32_1[motor->m_hfi.ind * motor->m_hfi.table_fact] * voltageNormalize;
} else {
motor->m_hfi.prev_sample = utils_tab_sin_32_1[motor->m_hfi.ind * motor->m_hfi.table_fact] * state_m->i_alpha -
utils_tab_cos_32_1[motor->m_hfi.ind * motor->m_hfi.table_fact] * state_m->i_beta;
mod_alpha_tmp -= hfi_voltage * utils_tab_sin_32_1[motor->m_hfi.ind * motor->m_hfi.table_fact] / ((2.0 / 3.0) * state_m->v_bus);
mod_beta_tmp += hfi_voltage * utils_tab_cos_32_1[motor->m_hfi.ind * motor->m_hfi.table_fact] / ((2.0 / 3.0) * state_m->v_bus);
mod_alpha_tmp -= hfi_voltage * utils_tab_sin_32_1[motor->m_hfi.ind * motor->m_hfi.table_fact] * voltageNormalize;
mod_beta_tmp += hfi_voltage * utils_tab_cos_32_1[motor->m_hfi.ind * motor->m_hfi.table_fact] * voltageNormalize;
}
utils_saturate_vector_2d(&mod_alpha_tmp, &mod_beta_tmp, SQRT3_BY_2 * 0.95);
@ -3985,8 +3991,11 @@ static void update_valpha_vbeta(volatile motor_all_state_t *motor, float mod_alp
// Keep the modulation updated so that the filter stays updated
// even when the motor is undriven.
if (motor->m_state != MC_STATE_RUNNING) {
mod_alpha = v_alpha / ((2.0 / 3.0) * state_m->v_bus);
mod_beta = v_beta / ((2.0 / 3.0) * state_m->v_bus);
/* voltageNormalize = 1/(2/3*V_bus) */
const float voltageNormalize = 1.5 / state_m->v_bus;
mod_alpha = v_alpha * voltageNormalize;
mod_beta = v_beta * voltageNormalize;
}
float abs_rpm = fabsf(RADPS2RPM_f(motor->m_pll_speed));