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Motor Control

How to Tune fweak on ZombieVerter VCU

Field weakening start frequency. Above this, motor enters constant-power region.

Quick Reference

Param ID

2

Unit

Hz

Range

0 — 1000

Default

90

🔍 See a sample config →

📖 What Does It Do?

Field weakening start frequency. Above this, motor enters constant-power region.

🎯 Recommended Values

Default value: 90

Valid range: 0 to 1000

Tuning Strategy

Start with the default value and adjust in small increments. Monitor vehicle behavior after each change before making further adjustments.

💡 Tuning Tips

CALCULATION: fweak = (battery_voltage / motor_rated_voltage) × motor_rated_freq

Example: 355V pack / 230V motor × 50Hz = 77 Hz

BASE SPEED (RPM) = fweak × 60 / polepairs

For 4-pole motor at 250Hz: 250×60/2 = 7500 RPM

TYPICAL VALUES:

  • Default: 90 (conservative)
  • Tesla SDU (400V): 220–290 Hz
  • Leaf EM57 (~360V): 250–300 Hz
  • Low-voltage: 34–100 Hz

    • Too LOW: more low-end torque but power drops early. Too HIGH: sluggish low end but pulls harder to top.

    INTERACTION: changing fweak shifts the whole V/Hz curve — boost needs re-tuning after.

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    🔗 Related Parameters

    Other parameters in the Motor Control category that work together with fweak:

    fmax

    Hz

    Maximum motor frequency. RPM = fmax × 60 / polepairs.

    boost

    dig

    Voltage at 0 RPM — controls starting torque. Higher = stronger launch.

    numimp

    ppr

    Speed sensor pulses per revolution.

    polepairs

    Motor pole pairs. CRITICAL — set this correctly for your motor.

    fslipmax

    Hz

    Maximum slip frequency (induction motors). Sets full-throttle torque.

    snsm

    enum

    Motor temperature sensor type. Must match your motor's actual sensor.

    fslipmin

    Hz

    Minimum slip frequency (induction motors). Sets creep torque.

    encmode

    enum

    Encoder/position sensor type. This is your motor's 'eyes' — it tells the inverter where the rotor is.

    dirchrpm

    rpm

    RPM below which direction change is allowed.

    udcnom

    V

    Nominal DC link voltage. 0 = auto-calculate from actual bus voltage.
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