| 摘要 |
A current sensor apparatus is disclosed for use with an inverter bridge that is controlled by a pulse width modulator (PWM) control apparatus and is connected to an inductive load. The current sensor apparatus includes a plurality of current sensors disposed in series with each of the low side switches in the inverter bridge. The PWM control apparatus samples the current sensors when the PWM control apparatus provides the necessary signals to open all of the high side switches in the inverter bridge and to close all of the low side switches. Due to the inductive nature of the load, the load current will continue to flow during the time in which the low side switches are closed and the high side switches are open. During this time, the current sensors are sampled and provide an output signal that is indicative of the magnitude of the current. The PWM control apparatus limits the duty cycle of the PWM signals to a predetermined value that is less than 100%. The actual value of the duty cycle limit is determined to ensure that the pulse width of the PWM signals is sufficiently wide to allow for accurate and reliable current sampling. If the load comprises motor windings that are connected in a "wye" configuration, the current sensors need only be inserted into all but one of the low side switch circuits. In this instance, the current that is not sensed may be derived from the measurements of the other currents.
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