# BLDC switching frequency

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tuloski
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Last seen: 4 years 2 months ago
Joined: 2018-09-11 11:53
Posts: 12
BLDC switching frequency

I see that in BLDC control there are two parameters for switching frequency: max and min. Is that because the PWM frequency is adapted on the go?

Can I put max and min the same value to keep a constant frequency?

bauck
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Last seen: 1 month 4 weeks ago
Joined: 2019-08-23 18:50
Posts: 4

Switching frequency is mapped according to dutycycle.

switching_frequency_now = (float)conf->m_bldc_f_sw_min * (1.0 - fabsf(dutyCycle)) + conf->m_bldc_f_sw_max * fabsf(dutyCycle);

Which is the same as (pseudocode):

switching_frequency = switching_frequency_min + dutycycle*(switching_frequency_max - switching_frequency_min)

You should be able to set max and min to the same value to keep a constant frequency.