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Motorola M68HC08 User Manual

Page 44

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BLDC Motor Control

Designer Reference Manual

DRM028 — Rev 0

44

BLDC Motor Control

MOTOROLA

The best commutation was get with Advance_angle:

60Deg*1/8 = 7.5Deg

which means Coef_HlfCmt = 0.375 at Running state

with default s/w setting

Per_Toff[n+1] = Per_ZCrosFlt*Coef_Toff and Per_Dis minimum

Coef_Toff = 0.375 at Running state, Per_Dis = 150

with default s/w setting

Per_ZCros0 <-- Per_ZCros[n]

T_ZCros0 <-- T_ZCros[n]

T2*[n] = T_ZCros[n] + HlfCmt[n]

If no back-EMF zero crossing was captured during preset
commutation period (T2P[n] then Corrective Calculation 1. is
made:

T_ZCros[n] <-- CmtT[n+1]

Per_ZCros[n] = T_ZCros[n] - T_ZCros[n-1] = T_ZCros[n] - T_ZCros0

Per_ZCrosFlt[n] = (1/2*Per_ZCros[n]+1/2*Per_ZCros0)

HlfCmt[n] = 1/2*Per_ZCrosFlt[n]-Advance_angle =

Coef_HlfCmt*Per_ZCrosFlt[n]

The best commutation was get with Advance_angle:

60Deg*1/8 = 7.5Deg

which means Coef_HlfCmt = 0.375 at Running state!

Per_Toff[n+1] = Per_ZCrosFlt*Coef_Toff and Per_Dis minimum

Per_ZCros0 <-- Per_ZCros[n]

T_ZCros0 <-- T_ZCros[n]

If back-EMF zero crossing is missed then Corrective Calculation
2.
is made:

T_ZCros[n] <-- CmtT[n]+Toff[n]

Per_ZCros[n] = T_ZCros[n] - T_ZCros[n-1] = T_ZCros[n] - T_ZCros0

Per_ZCrosFlt[n] = (1/2*T_ZCros[n]+1/2*T_ZCros0)

HlfCmt[n] = 1/2*Per_ZCrosFlt[n]-Advance_angle =

Coef_HlfCmt*Per_ZCrosFlt[n]

The best commutation was get with Advance_angle:

60Deg*1/8 = 7.5Deg

which means Coef_HlfCmt = 0.375 at Running state!

Per_ZCros0 <-- Per_ZCros[n]

T_ZCros0 <-- T_ZCros[n]

Where:

T_Cmt = time of the last commutation

T2 = Time of the Timer 2 event (for Timer Setting)

T_ZCros = Time of the last zero crossing

T_ZCros0 = Time of the previous zero crossing

Per_Toff = Period of the zero crossing off

Per_ZCros = Period between zero crossings (estimates required

commutation period)

Per_ZCros0 = Pervious period between zero crossings

Per_ZCrosFlt = Estimated period of commutation filtered

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Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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