Sgs-thomson Microelectronics S.a.

Commissariat a L'energie Atomique

Stmicroelectronics S.a.

Bruno Maurice

Jean-Marie Bourgeois

Jean-Marie Charreton

Pierre Guillemin

Bernard Saby

Michel Roumeguere

Jacques Champon

A method and apparatus for controlling a brushless motor having a plurality of windings switched through a sequence of steps includes determining a transition time from one step to the next. The transition time is determined by detecting a zero crossing of a back emf in one of the plurality of windings. A delayed time to be added to the transition time is determined wherein the delayed time is selected according to the step in the sequence of steps being executed and is dependent on the duration of one of a preceding interval between zero crossings. A delay time proportional to a duration of a last shortest interval is supplied to follow a longest interval. A delay time proportional to a duration of a last longest interval is supplied to follow a shortest interval and a delay time proportional to a duration of a medium interval is supplied to follow a medium interval. The method may be used, for example, with a star or delta connected motor having any number of windings.

Control of a brushless motor

The invention provides a method for controlling a brushless motor, with windings connected in star (`wye`) formation, including the steps of periodically applying a supply voltage between first and second windings, detecting the presence of a current in a third winding, and an instant of cessation of that current, monitoring the value of a back emf induced in the third winding and detecting a zero crossing point of the back emf, timing a predetermined delay from the zero crossing point, and after the end of the delay, applying the supply voltage to other windings. The invention also provides a method for use with motors having windings connected in delta formation.

A system provides parallel sequences of control signals, each control signal having a determined duration (T), constant within a sequence, and a predetermined duty cycle, specific to the control signal. A microcontroller (20) includes a central processing unit (21) and a non-volatile memory (23) arranged in blocks (Bij) of lines and columns. Each line corresponds to a word containing at least as many bits as parallel sequences. A Direct Memory Access (DMA) controller (24) and an associated counter (25) sequentially address each word of a block at a fixed frequency and supply bits of this word in parallel to produce the parallel control signals.

System for controlling an inverter through pulse width modulation

An irradiation-stable, temperature-compensated Zener diode and a process for producing the Zener diode. The diode includes a first pn junction having metallic impurities diffused into the corresponding type n region, a second pn junction with a type n region differing from that of the first pn junction, the two junctions being interconnected so that the first junction is forward-biased while the second junction is reversed-biased. Two metal layers acting as electrical contacts are deposited on each p region and there are two insulating layers.

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Eguilles, France

Bruno Maurice