Patent ID: 7667421

Claim:
A torque compensation system, comprising: a DC brushless motor, having an asymmetric load; a shunt resistor, having a first terminal connected to a ground; a DC/AC inverter, connected to a DC voltage by a first power input terminal and connected to a second terminal of shunt resistor by a second power input terminal, for generating a plurality of driving currents to the DC brushless motor in response to a plurality control signals, wherein the plurality of driving currents start from the DC voltage and then flow through the DC brushless motor and through the shunt resistor to reach the ground; a position detecting circuit, for generating a plurality of position signals in response to a rotating position from the DC brushless motor; and a control unit, for determining a plurality of absolute rotor positions in response to the position signals, wherein the control unit has a sampling terminal connected to the second power input terminal for calculating an average current and an instant current flowing through the shunt resistor and adjusts the control signals in response to the average current and the instant current.