Design of an integrated circuit controller for brushless DC drives

The authors describe the design of an application-specific integrated circuit (ASIC) controller for brushless DC drives of the trapezoidal type. Cascade control is usually used for such drives, with an inner loop controlling motor current or torque and an outer loop controlling motor speed. In addition a position control loop may be needed if the drive is employed in a positioning application. The integrated circuit controller incorporates both the torque and speed control loops. In order to maximise the applicability of the circuit a digital interface is included, so that, if necessary, information can be transferred between the circuit and an external computer. Therefore the circuit may be applied in a variety of situations, ranging from speed control of a single drive, with no external control functions, to control of one axis in a multi-axis machine, with operation overseen by a host computer