Configuration parameters

Reference for all key mc_configuration parameters with their default values from mcconf_default.h.

All parameters belong to the mc_configuration struct defined in datatypes.h. Default values are set in motor/mcconf_default.h and can be overridden per hardware target.

Hardware-specific builds may override any of these defaults. The values shown here are the firmware-wide defaults that apply when no hardware override is present.

Current limits

Parameter	Default	Description
l_current_max	60.0 A	Maximum motor phase current (upper limit).
l_current_min	-60.0 A	Minimum motor phase current (lower limit, negative for braking).
l_in_current_max	99.0 A	Maximum input (battery) current draw.
l_in_current_min	-60.0 A	Minimum input current (negative = regen current back into battery).
l_abs_current_max	130.0 A	Hard absolute current limit — triggers FAULT_CODE_ABS_OVER_CURRENT immediately.
l_current_max_scale	1.0	Scale factor applied to l_current_max at runtime.
l_current_min_scale	1.0	Scale factor applied to l_current_min at runtime.
l_in_current_map_start	1.0	Input current to Q-axis current limit map start threshold.
l_in_current_map_filter	0.005	Low-pass filter constant for the mapped input current limit.
l_watt_max	1,500,000 W	Maximum output power. Set to a practical value for the drive system.
l_watt_min	-1,500,000 W	Minimum output power (maximum braking power).

Setting l_abs_current_max above the hardware current rating can destroy MOSFETs. Always set this below the gate driver and FET peak current specification.

Voltage limits

Parameter	Default	Description
l_min_vin	8.0 V	Minimum input voltage — triggers FAULT_CODE_UNDER_VOLTAGE below this.
l_max_vin	57.0 V	Maximum input voltage — triggers FAULT_CODE_OVER_VOLTAGE above this.
l_battery_cut_start	10.0 V	Input voltage at which positive current output begins to ramp down.
l_battery_cut_end	8.0 V	Input voltage at which positive current output is cut to zero.
l_battery_regen_cut_start	1000.0 V	Input voltage at which regen current begins to ramp down (set very high to effectively disable).
l_battery_regen_cut_end	1100.0 V	Input voltage at which regen current is cut to zero.

Set l_battery_cut_start and l_battery_cut_end to match your battery chemistry’s minimum cell voltage multiplied by cell count, to protect cells from deep discharge.

Temperature limits

Parameter	Default	Description
l_temp_fet_start	85.0 °C	MOSFET temperature at which current begins to be reduced.
l_temp_fet_end	100.0 °C	MOSFET temperature at which the motor is shut off (FAULT_CODE_OVER_TEMP_FET).
l_temp_motor_start	85.0 °C	Motor temperature at which current begins to be reduced.
l_temp_motor_end	100.0 °C	Motor temperature at which the motor is shut off (FAULT_CODE_OVER_TEMP_MOTOR).
l_temp_accel_dec	0.15	Fraction by which temperature limits are reduced during acceleration to prevent thermal runaway.
m_motor_temp_sens_type	TEMP_SENSOR_NTC_10K_25C	Type of motor temperature sensor.
m_ntc_motor_beta	3380.0	Beta coefficient for the NTC motor thermistor.
m_ptc_motor_coeff	0.61 %/K	Resistance change coefficient for PTC sensors.

RPM limits

Parameter	Default	Description
l_max_erpm	100,000 ERPM	Maximum electrical RPM (upper).
l_min_erpm	-100,000 ERPM	Minimum electrical RPM (lower).
l_erpm_start	0.8	Fraction of l_max_erpm at which RPM-based current limiting begins.
l_max_erpm_fbrake	300 ERPM	Maximum ERPM at which full braking is applied.
l_max_erpm_fbrake_cc	1500 ERPM	Maximum ERPM at which full braking is applied under current control.
l_min_duty	0.005	Minimum duty cycle.
l_max_duty	0.95	Maximum duty cycle.
l_duty_start	1.0	Duty cycle fraction at which current limiting begins (1.0 = disabled).

Motor parameters

These parameters describe the physical motor and are normally determined by running motor detection in VESC Tool.

Parameter	Default	Description
si_motor_poles	14	Number of motor poles (pole count, not pole pairs).
si_gear_ratio	3.0	Drive gear ratio (motor revolutions per wheel revolution).
si_wheel_diameter	0.083 m	Wheel diameter in meters, used for speed and odometer calculations.
si_battery_type	BATTERY_TYPE_LIION_3_0__4_2	Battery chemistry selection for display and BMS integration.
si_battery_cells	3	Number of cells in series.
si_battery_ah	6.0 Ah	Battery capacity in amp-hours.
si_motor_nl_current	1.0 A	Motor no-load current, used for efficiency calculations.
foc_motor_l	7 µH	Phase inductance (L). Set by motor detection.
foc_motor_r	15 mΩ	Phase resistance (R). Set by motor detection.
foc_motor_flux_linkage	0.00245 Wb	Motor flux linkage (λ). Set by motor detection.
foc_motor_ld_lq_diff	0.0 H	Difference between d-axis and q-axis inductance (saliency).

The default motor parameters are placeholders. Always run motor detection for accurate FOC operation.

FOC parameters

Current controller

Parameter	Default	Description
foc_current_kp	0.03	Proportional gain of the d/q axis current PI controller.
foc_current_ki	50.0	Integral gain of the d/q axis current PI controller.
foc_f_zv	25,000 Hz	Zero-vector (switching) frequency for FOC.
foc_dt_us	0.12 µs	Dead-time compensation in microseconds.
foc_cc_decoupling	FOC_CC_DECOUPLING_DISABLED	Cross-coupling compensation mode for the current controller.
foc_sat_comp_mode	SAT_COMP_DISABLED	Stator saturation compensation mode.
foc_sat_comp	0.0	Stator saturation compensation factor.
foc_current_filter_const	0.1	Low-pass filter constant for displayed/logged currents.
foc_overmod_factor	1.0	Overmodulation factor (>1.0 enables overmodulation).

Observer

Parameter	Default	Description
foc_observer_type	FOC_OBSERVER_MXLEMMING_LAMBDA_COMP	Position observer algorithm.
foc_observer_gain	9×10⁷	Observer feedback gain. A starting point is approximately 600 / L.
foc_observer_gain_slow	0.05	Fraction of foc_observer_gain used at minimum duty cycle.
foc_observer_offset	-1.0	Observer angle offset in timer update cycles.
foc_pll_kp	2000.0	PLL proportional gain used by the speed tracker.
foc_pll_ki	30,000.0	PLL integral gain used by the speed tracker.

Sensor mode and open-loop

Parameter	Default	Description
foc_sensor_mode	FOC_SENSOR_MODE_SENSORLESS	Sensor mode: sensorless, encoder, hall, HFI, or variants.
foc_sl_erpm	3500 ERPM	ERPM above which only the observer is used (hybrid mode transition).
foc_sl_erpm_start	2500 ERPM	ERPM below which only sensored commutation is used (hybrid mode).
foc_openloop_rpm	1500 ERPM	Target RPM during open-loop startup or index-finding.
foc_openloop_rpm_low	0.0	Fraction of foc_openloop_rpm at minimum current.
foc_sl_openloop_hyst	0.1 s	Time below minimum RPM before open-loop is activated.
foc_sl_openloop_time	0.05 s	Time to remain in open-loop after RPM ramp.
foc_sl_openloop_time_lock	0.0 s	Time to lock rotor at start of open-loop sequence.
foc_sl_openloop_time_ramp	0.1 s	Time to ramp up to open-loop speed.

Field weakening

Parameter	Default	Description
foc_fw_current_max	0.0 A	Maximum negative d-axis current for field weakening (0 = disabled).
foc_fw_duty_start	0.8	Duty cycle fraction at which field weakening begins.
foc_fw_ramp_time	0.0 s	Ramp time for field weakening current.
foc_fw_q_current_factor	0.05	Fraction of field weakening current fed to the q-axis when target current is 0.

Field weakening increases motor and FET stress. Start with foc_fw_current_max set to a small fraction of l_current_max and monitor temperatures carefully.

HFI (High Frequency Injection)

Parameter	Default	Description
foc_hfi_voltage_start	20 V	Injection voltage during ambiguity resolution at start.
foc_hfi_voltage_run	4 V	Injection voltage during normal HFI tracking.
foc_hfi_voltage_max	6 V	Injection voltage at maximum current.
foc_hfi_gain	0.3	Correction gain for HFI V2 mode.
foc_hfi_max_err	0.30 rad	Maximum HFI angle error before truncation (noise rejection).
foc_hfi_hyst	0.0	Sense vector offset hysteresis.
foc_sl_erpm_hfi	3000 ERPM	ERPM above which the observer takes over from HFI.
foc_hfi_reset_erpm	500 ERPM	ERPM below which the HFI state is reset.
foc_hfi_samples	HFI_SAMPLES_16	Number of HFI injection samples per electrical revolution.
foc_hfi_start_samples	5	Number of samples taken at start for ambiguity resolution.
foc_hfi_obs_ovr_sec	0.001 s	Duration to continue using the observer when entering HFI speed range.
foc_hfi_amb_mode	FOC_AMB_MODE_SIX_VECTOR	HFI ambiguity resolution mode.
foc_hfi_amb_current	60.0 A	Current used during HFI ambiguity resolution.
foc_hfi_amb_tres	15	Ambiguity resolution threshold.

Phase filter

Parameter	Default	Description
foc_phase_filter_enable	true	Enable hardware phase voltage filters when available.
foc_phase_filter_disable_fault	true	Disable FAULT_CODE_PHASE_FILTER (fault suppressed by default).
foc_phase_filter_max_erpm	4000 ERPM	Use phase voltage filter only below this ERPM.

Temperature compensation and MTPA

Parameter	Default	Description
foc_temp_comp	false	Enable motor resistance temperature compensation.
foc_temp_comp_base_temp	25.0 °C	Reference temperature for resistance compensation.
foc_mtpa_mode	MTPA_MODE_OFF	Maximum torque per amp algorithm mode.

Speed PID parameters

Parameter	Default	Description
sp_pid_loop_rate	PID_RATE_1000_HZ	PID loop execution rate (shared by speed and position PID).
s_pid_kp	0.004	Speed PID proportional gain.
s_pid_ki	0.004	Speed PID integral gain.
s_pid_kd	0.0001	Speed PID derivative gain.
s_pid_kd_filter	0.2	Low-pass filter constant for the speed PID derivative term.
s_pid_min_erpm	900 ERPM	Minimum ERPM for the speed PID (below this, output is zero).
s_pid_allow_braking	true	Allow the speed PID to apply braking current.
s_pid_ramp_erpms_s	25,000 ERPM/s	Speed setpoint ramp rate.
s_pid_speed_source	S_PID_SPEED_SRC_PLL	Speed source used by the PID controller.

Position PID parameters

Parameter	Default	Description
p_pid_kp	0.025	Position PID proportional gain.
p_pid_ki	0.0	Position PID integral gain.
p_pid_kd	0.0	Position PID derivative gain (error-based).
p_pid_kd_proc	0.00035	Position PID derivative gain (process-variable-based).
p_pid_kd_filter	0.2	Low-pass filter constant for the position PID derivative term.
p_pid_ang_div	1.0	Divide angle error by this value before the PID.
p_pid_gain_dec_angle	0.0	Reduce PID gains when error is below this angle.
p_pid_offset	0.0 °	Angle offset added to the position setpoint.

Miscellaneous parameters

Parameter	Default	Description
m_fault_stop_time_ms	500 ms	Duration for which motor commands are ignored after a fault clears.
m_duty_ramp_step	0.02	Maximum duty cycle ramp step per millisecond in duty control mode.
m_current_backoff_gain	0.5	Gain of the current limiting backoff algorithm.
m_encoder_counts	8192	Number of encoder counts per revolution.
m_sensor_port_mode	SENSOR_PORT_MODE_HALL	Mode of the combined hall/encoder sensor port.
m_invert_direction	false	Invert the motor rotation direction.
m_drv8301_oc_mode	DRV8301_OC_LIMIT	Gate driver over-current protection mode.
m_drv8301_oc_adj	16	Gate driver over-current protection threshold (0–31).
m_bldc_f_sw_min	3,000 Hz	Minimum switching frequency in BLDC mode.
m_bldc_f_sw_max	35,000 Hz	Maximum switching frequency in BLDC mode.
m_dc_f_sw	25,000 Hz	Fixed switching frequency in DC motor mode.
m_out_aux_mode	OUT_AUX_MODE_OFF	Auxiliary output pin behavior.
m_hall_extra_samples	3	Extra ADC samples averaged when reading hall sensors.
m_batt_filter_const	45	Battery voltage display filter time constant.