Motor current measurement using time-modulated signals

A new approach to motor drive current measurement begins by challenging the assumption that high sensor bandwidth is mandatory. The fundamental motor phase current of interest has a relatively low bandwidth, except for the PWM ripple current riding on top of it. If sampling of motor current can be synchronized to the PWM carrier, the ripple current can be canceled out. Therefore, it is sample timing accuracy rather than bandwidth that provides greater overall accuracy. A new synchronous-sampling HVIC is presented, that converts the measured current directly to a digital timing-based signal for high resolution at low cost. This avoids the complexity and signal degradation that occurs in traditional approaches where the signal is reconstructed in analog format, only to be re-sampled back to a digital format again