DC-DC boost converter for spindle motor control

#The present invention relates to a process and a circuit for control of the rotational speed of a direct current motor, particularly for use as the drive of magnetic or optical data carriers, wherein the motor has a rotor with a plurality of permanent magnet poles and a stator with a plurality of windings which are fed with a motor current by means of a switching unit for commutation, wherein, by means of the motor current, a magnetic flux is induced generating the torque of the rotor.

#Modern drives of magnetic or optical data carriers customarily use brushless direct current motors to drive the spindle carrying the data carrier, or to drive the transport unit for the magnetic tape or other data carrier.

#An example of such a data carrier system is a disk drive, which uses floating read/write heads that start off and land on the disk surface. This means that the read/write heads and the disks go through critical phases of friction during which there is a high risk of damage or destruction of the data carrier. There is also a risk of damage to the read/write heads. It is accordingly desirable that the start off and landing phases be as short as possible. However, this requires that the motor have a high starting torque and stopping, or breaking, torque.

#The embodiment of the invention is described in more detail with reference to the drawings. In the drawings:

#FIG. 1 is a block diagram of a circuit for the control of the speed of a direct current motor in accordance with the invention;

#FIG. 2 is a schematic diagram of a boost converter in accordance with the invention;

#The block diagram of FIG. 1 depicts a direct current boost converter 1, which represents a current converter for direct current. A supply voltage V.sub.in, which provides an input current I.sub.in, is applied to the input of the boost converter 1. At the output of the boost converter 1, an output current I.sub.out is provided, as is an output voltage V.sub.out, which is fed to a motor bridge 2. The motor bridge 2 is used, as is set out below, for commutation of the motor current fed to a motor 3.

#The motor 3 can serve as the drive for the spindle of an optical or magnetic data carrier, such as a fixed disk, a magnetic tape, or the like. The motor 3 can also serve as the drive for the mirror of a laser printer.

#From the motor 3, position signals are derived in customary fashion which are fed to the commutation logic 4 and to an adaptive motor voltage generator 5.