| 摘要 |
A power amplifier (18) for driving a brushless DC motor (22) includes a processor (40) which receives a signal indicative of motor situational usage and generates a mode state signal indicative of which one of a plurality of amplification modes is to be implemented in response to the received signal. The amplification modes include a linear mode and a switching mode, with the switching mode including a two quadrant switching mode and a four quadrant switching mode. The amplifier (18) further includes a controller (50) which, in response to the mode state signal, generates control signals for each of coil drive circuits (26) associated with the motor. Further, in response to a signal indicative of motor situational usage, processor (40) generates a power state signal which causes controller (50) to connect coil drive circuits (26) to a suitable one of a plurality of differing voltage sources (21, 23). The power amplifier (18) has particular employment for a reel motor (22S, 22T) for a helical scan recorder (100) which records information on magnetic tape (102).
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