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PROGRAM ROZWOJOWY

^1 POLITECHNIKI WARSZAWSKIEJ

By adjusting the turn-on and turn-off angles so that the phase commutation begins sooner, we gain the advantage of producing current in the winding while the inductance is Iow (the current reaches its maximum - at 0_mc, sooner and at a higher level and thus produce morę torque), and also of having additional time to reduce the current in the winding before the rotor reaches the negative torąue region (the turn - off process of a phase starts at 8_C < 9_m and terminates at 0_Off in the "generating" zonę). Control of the firing angles can be accomplished a number of ways, and is based on the type of position feedback available and the optimization goal of the control. When position information is morę precisely known, a morę sophisticated approach can be used. One approach is to continuously vary the turn-on angle with a fixed dwell.

Near tum-on, equation (1.17) can be approximated as:

di/./j dij Sij dt

di i

(1.27)

Multiplying each side of equation (1.27) by the differential, d0, and sotaing for d0, gives:

^dS=rr:r-    ⁽¹-²⁸⁾

U, dt

and using first order approximations yields an equation for calculating advance angle:

where: ij is the desired phase current and Ub_US is the DC bus voltage. 1.4. CONNECTING AND COMMUTATION PROCESS

Fig. 1.13. Connecting process. General law that governs this Circuit is as follow:

(1.31)

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UNIA EUROPEJSKA

EUROPEJSKI FUNDUSZ SPOŁECZNY

U = Ri + L— dt

a KAPITAŁ LUDZKI

NAROOOWA STRATEGIA SPOjNOS

Materiały dydaktyczne dystrybuowane bezpłatnie.

Projekt współfinansowany ze środków Unii Europejskiej w ramach Europejskiego Funduszu Społecznego