CPC H02P 8/34 (2013.01) | 17 Claims |
5. A circuit for detecting a load condition, the circuit comprising:
a bridge circuit that comprises:
a first switch having a first internal resistance;
a second switch having a second internal resistance; and
a coil that operates as at least one of a motor or a generator;
a control circuit coupled to the bridge circuit, the control circuit performing steps comprising:
obtaining an effective PWM coil voltage by causing a first PWM voltage to be applied to the coil in a first direction and causing a second PWM voltage to be applied to the coil in a second direction opposite to the first direction;
in response to the effective PWM coil voltage being zero, determining, between a first voltage at the first internal resistance and a second voltage at the second internal resistance, a difference voltage that, in response to being zero, indicates a current zero-crossing; and
using the difference voltage to generate a current zero-crossing signal;
a difference generator that, in response to receiving a phase angle of a predetermined coil voltage, generates a phase angle difference signal.
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