Revision as of 02:34, 4 August 2009

Copley supply voltage

• Peak motor input power : 25.2V * 30 amps = 756 watts
• torque advantage : 25k/7k = 3.57
• Maximum motor current = 30amps / 3.57 = 8.4amps

ir drop

• R = (450mohm + 160 mohm) * 3/4 (R of motor and inductors)
• IR = 3.4V

V=Ldi/dt

• L = (102uH + 160uH) * 3/4 = 200uH
• I=Io * sin(ft)
• f = 25krpm/60 * 2 elec cycles * 2pi = 5236 rads
• dI/dt=f * Io * cos(t) = f * Io (peak) = 5236 * 8.4 = 44e3 Amps/sec
• V = 200uH * 44e3 = 8.8V

back EMF

• EC30 speed const = 355 rpm/volt : 25000 = 70.4V

total supply

• total voltage = 70.4 + 3.4 + 8.8 = 82.6V
• max PWM = 96% (estimate) -> 86 volts needed on copley

What if only 4.2 amps at peak speed

• LdI/dt = 4.4V
• IR = 1.7V
• back EMF = 70.4VV
• total supply = 76.5/.96 = 79.7V

What if 4.2 amps at 23000 rpm

• LdI/dt = 4.05V
• IR = 1.7V
• back EMF = 64.8V
• total supply = 70.55/0.96 = 73.5V

Inductors

• [12 awg, 80uH, 50mohm air core]
• [500 KHZ, 85uH, Isat=17A, PN: 323-18 (WCM323 series)]
• [PDF (Switcher as application) 100uH, Isat=13.0A]
• [Digikey 1KHZ : 100uH, 14A, 18mohm]
• [Digikey 1KHZ : 100uH, 14.4A, 25mohm]

Power Supplies

• [54V-80V, 500W DIN rail]

• [Open frame unregulated linear $204]

• [28.8-40V 8.7A 313W $125 ]
• [40-57V 6.7A 321W $125]