"Peak Efficiency" Control Mode?

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devin
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Joined: 08 May 2017, 01:55
Location: San Francisco, California, US
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Re: "Peak Efficiency" Control Mode?

Postby devin » 27 May 2018, 01:11

This update calculates battery current, motor current and electrical wattage targets for control loop implementation. Please note there are presently 2 throttle variations of efficiency control - watt control throttle & motor current control throttle (both variations updated here). In BLDC / block commutation mode the motor current target probably makes the most sense to use for a control loop. In FOC mode, I envision the battery current or electrical wattage target being used for the control loop.

------------------------------

Efficiency Control
Watt Control Throttle Variation
Control Loop Targets

Settings:

M= 100% = Throttle % Setting
K= 90% = Desired Efficiency % Setting
L= 500w = Desired Min Watts Available Setting
P= 4500w = Desired Max Watts Available Setting
Y= 120a = X*(sqrt(3)/2) = Max Motor Amps BLDC
X= 138.56a = Y/(sqrt(3)/2) = Max Motor Amps FOC
Z= 95% = Max Duty Cycle %

Observables:

G= 48.2v = Battery Voltage
D= 16.94v = Back EMF Voltage
F= 0.025ohm = Winding Resistance Ohms

Control Loop Targets:

A= XX.XXXa = Battery Amps
B= XX.XXXa = Motor Amps (BLDC)
W= XX.XXXa = B/(sqrt(3)/2) = Peak Phase Current FOC
H= XX.XXXw = Throttled Wattage
N= XX.XXXw = Desired Full Throttle Wattage
C= XX.XXX% = Duty Cycle
E= XX.XXXv = Effective PWM Voltage


N=L
&
if D>((sqrt(F)*K*sqrt(L))/(10*sqrt(100-K))) then N=(-1)*((100*(D^2)*(K-100))/(F*(K^2)))
&
if N>P then N=P
&
if Y<((sqrt((D^2)+(4*F*N))-D)/(2*F)) then N=Y*(D+(F*Y))
&
if Z<((50*(sqrt((D^2)+(4*F*N))+D))/G) then N=(G*Z*(G*Z-(100*D)))/(10000*F)
&
C=10*((sqrt((25*(D^2))+(F*M*N))/G)+((5*D)/G))
&
E=G*(C/100)
&
B=(E-D)/F
&
H=B*E
&
A=H/G
&
repeat

Therefore:

Instantaneous Control Loop Targets:

A= 29.400a = Battery Amps
B= 75.264a = Motor Amps (BLDC)
W= 86.90a = B/(sqrt(3)/2) = Peak Phase Current FOC
H= 1417.10w = Throttled Wattage
N= 1417.10w = Desired Full Throttle Wattage
C= 39.049% = Duty Cycle
E= 18.821618v = PWM Effective Voltage

------------------------------

Efficiency Control
Motor Current Control Throttle Variation
Control Loop Targets

Settings:

M= 100% = Throttle % Setting
K= 90% = Desired Efficiency % Setting
L= 500w = Desired Min Watts Available Setting
P= 4500w = Desired Max Watts Available Setting
Y= 120a = X*(sqrt(3)/2) = Max Motor Amps BLDC
X= 138.56a = Y/(sqrt(3)/2) = Max Motor Amps FOC
Z= 95% = Max Duty Cycle %

Observables:

G= 48.2v = Battery Voltage
D= 16.94v = Back EMF Voltage
F= 0.025ohm = Winding Resistance Ohms

Control Loop Targets:

A= XX.XXXa = Battery Amps
B= XX.XXXa = Motor Amps (BLDC)
W= XX.XXXa = B/(sqrt(3)/2) = Peak Phase Current FOC
H= XX.XXXw = Throttled Wattage
N= XX.XXXw = Desired Full Throttle Wattage
C= XX.XXX% = Duty Cycle
E= XX.XXXv = Effective PWM Voltage

Where:

N=L
&
if D>((sqrt(F)*K*sqrt(L))/(10*sqrt(100-K))) then N=(-1)*((100*(D^2)*(K-100))/(F*(K^2)))
&
if N>P then N=P
&
if Y<((sqrt((D^2)+(4*F*N))-D)/(2*F)) then N=Y*(D+(F*Y))
&
if Z<((50*(sqrt((D^2)+(4*F*N))+D))/G) then N=(G*Z*(G*Z-(100*D)))/(10000*F)
&
H=(M*((-1)*D*(M-100)*sqrt((D^2)+4*F*N)+((D^2)*(M-100))+(2*F*M*N)))/(20000*F)
&
C=((50*(sqrt((D^2)+(4*F*H))+D))/G)
&
E=G*(C/100)
&
B=(E-D)/F
&
A=H/G

repeat

Therefore:

Instantaneous Control Loop Targets:

A= 29.400a = Battery Amps
B= 75.264a = Motor Amps (BLDC)
W= 86.90a = B/(sqrt(3)/2) = Peak Phase Current FOC
H= 1417.10w = Throttled Wattage
N= 1417.10w = Desired Full Throttle Wattage
C= 39.049% = Duty Cycle
E= 18.821618v = PWM Effective Voltage

———————-

For Illustration:

classical settings: 100% throttle, 300a battery amp limit, 300a motor amp limit, 33.2v battery, 850kv 0.0135ohm motor, 120mm tire diamter, 4:1 gear reduction, 2 motors

efficiency control settings: 100% throttle, 300a battery amp limit, 300a motor amp limit, 87.5% desired efficiency setting, 200w minimum electrical wattage setting, 9960w maximum electrical wattage setting, 33.2v battery, 850kv 0.0135ohm motor, 120mm tire diamter, 4:1 gear reduction, 2 motors

Image


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