Texas Instruments Corporation

Hughes Aircraft Company

Vincent T Ng

Bert White

Mehedi Hassan

Bertram John White

Fredrick W Trafton

Michael Arkin

Joyce Taylor

Frank Bohac

A control circuit for motor current including a circuit to generate a voltage to indicate the actual motor current, a first convert circuit to convert the voltage indicative of the motor current to a current, a compare circuit to compare the current indicating the motor current with a reference current and generate a difference current between the current indicating the motor current and the reference current, and a second convert circuit to convert the difference current to a voltage to indicate a difference in motor current from the reference current.

Current mode approach to spindle motor current control and rotor position sense

A method and circuit are presented for operating a polyphase dc motor in which drive voltages are applied to the windings of the motor in predetermined phases. Zero crossings of currents flowing in respective windings of the motor are detected, and phases of the drive voltages are adjusted to have zero crossings substantially simultaneously with the detected zero crossings of the currents flowing in respective windings of the motor. The method includes generating a set of three waveforms (,) to provide drive voltages to respective windings of the motor. Each waveform has a period of 360&deg; with a first segment (,) having a value of zero for 120&deg;, followed by a second segment (,) having an &ldquo;up slope&rdquo; shape for 60&deg;, followed by a third segment (,) having two consecutive &ldquo;cap&rdquo; shapes for 120&deg;, followed by a fourth segment (,) having &ldquo;down slope&rdquo; shape for 60&deg;. Each waveform of said set is displaced from one another by 120&deg;. As a result, the acoustic motor noise is reduced.

Silent spin sine wave generator

A method and circuit for operating a polyphase dc motor in which discontinuous sinusoidal drive voltages are applied to the windings of the motor in predetermined phases. The discontinuous portion of the sinusoid is timed with the bemf zero crossings. Bemf zero crossings are detected, and phases of the drive voltages are adjusted to have zero crossings substantially in the discontinuities of the drive voltages. The method and circuit result in motor operation with significantly reduced acoustic motor noise.

Method and apparatus for synchronizing PWM sinusoidal drive to a DC motor

A pseudo-random switched resistor for emulating a relatively high input impedance. The switched resistor comprises a relatively low value resistor, a semiconductor switch coupled to the resistor, and a pseudo-random pulse generator coupled to the switch for controlling the on time of the switch to emulate the relatively high input impedance. The random pulse generator comprises a plurality of cascaded circuits that are coupled to a flip flop. The plurality of cascaded circuits each comprise a shift register for receiving clock signals and for generating a sequence of (2.sup.N -1) pseudo-random numbers and a terminal count pulse at the end of every sequence, an N-bit binary counter for receiving the terminal count pulse which clocks it, and an equivalence circuit for comparing the outputs of the shift register and the binary counter and for generating an output signal when there is a match. The flip-flop generates a pulse to close the switch whenever there is a match between the output of the shift register and the binary counter as determined by the equivalence circuit.

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Alhambra, CA, United States of America

Vincent T Ng