Delta Tau Geo Direct PWM Amplifier Instalační manuál stáhnout pdf (Strana 39)

GEO Direct PWM Amplifiers – Preliminary Documentation

Troubleshooting 33

CALCULATING MINIMUM PWM FREQUENCY

The minimum PWM frequency requirement for a system is based on the time constant of the motor.

Calculate the minimum PWM frequency to determine if the amplifier will properly close the current loop.

Systems with very low time constants need the addition of chokes or in-line inductive loads to allow the

PMAC to properly close the current loop of the system. In general, the lower the time constant of the

system, the higher the PWM frequency must be.

Calculate the motor time constant by dividing the motor inductance by the resistance of the phases.

motor

The relationship used to determine the minimum PWM frequency is based on the following equation:

πτ

)Hz(PWM

)Hz(PWM2

=∴

Example:

moto r

= 5.80 mH

motor

= 11.50 Ω

secm504.0

50.11

mH80.5

motor

Ω

Therefore,

sec)m504.0(2

)Hz(PWM

6316 Hz

Based on this calculation, set the PWM frequency to at least 6.32kHz.

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Delta Tau Geo Direct PWM Amplifier Instalační manuál Strana 39