| 摘要 |
<p>A stepping motor drive circuit, where the phase windings (1, 3 and 2, 4) are magnetically coupled in pairs, comprises current chopping control circuits (23, 24) controlling the switching on/off of driving transistors (5, 6, 7, 8) each coupled to a respective winding, and circuits associated to each switching transistor 5,6,7,8 for reducing their storage times and therefore their switching losses.</p><p>Particularly, with reference to one switching transistor (5) the related circuit for storage time reduction comprises a capacitor (25) and a diode (45), series connected, such series being connected between a terminal of the winding (2) maghetically coupled to the one (1) associated with the switching transistor under consideration (5) and the base of such transistor (5). The circuit, as soon as such transistor (5) is controlled to switch from ON to OFF, applies a reverse voltage pulse to the base of the transistor (5) thus allowing a fast transition towards the cutoff region.</p><p>in such way, for high chopping frequency, besides improving the stepping motor efficiency, it is possible to use switching transistors with lower dissipable power and less expensive.</p> |
