Fig. 1.15. Instantaneous value of voltage and current in winding coil during “switch on" and "switch off ’ processes.
Equivalent electronic Circuit is shown in Fig.l.l7a, where commutation diodę allows creating short Circuit for inductance current after “switch off’ the main power transistor. Winding coil deenergizing process is slow and depends on Circuit time constant r = L/R. The instantaneous value of RRSRM phase current is presented in Fig.l. 16.
Fig. 1.16. RRSRM phase current during one fuli shaft revolution. One key switch operation. Energy "pumped" out time is much longer than energy "pumped" in time for each conduction cycle.
To avoid breaking torque production due to existing the current during angle 0Off - 0m some techniques are used to shorten deenergizing process. One possibility is to reverse voltage during switch off process using the unipolar current bridge per phase (Fig. 1.17b).
UNIA EUROPEJSKA
EUROPEJSKI FUNDUSZ SPOŁECZNY
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Materiały dydaktyczne dystrybuowane bezpłatnie.
Projekt współfinansowany ze środków Unii Europejskiej w ramach Europejskiego Funduszu Społecznego
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