Driving of a single coil brushless DC motor

A method for controlling a single coil brushless DC motor having an electrical time constant, the method comprising EHP sequences which comprise a pulse train which comprises at least two driving pulses of a same polarity, in which each driving pulse comprises:

• applying a driving signal during a torque generating period (TGP), to increase a phase current, followed by a non-torque generating period (NTGP), during which the phase current is reducing,
• monitoring the phase current during a sensing window thereby obtaining phase current information, wherein the sensing window lasts at least during a time constant, which is the electrical time constant or an approximation of the electrical time constant, if the sensing window is during the TGP, and wherein the sensing window minimally lasts until the phase current has reduced to less than half the maximum phase current which was generated during the TGP if the sensing window is during the NTGP,
• and determining parameters for the ongoing EHP, and/or for at least one next EHP sequence based on the obtained phase current information,
• wherein the sensing window is during the NTGP, and where the NTGP comprises a recirculation period wherein during at least one recirculation period the phase current decays below a predefined current threshold, and
• as soon as one driving pulse with a recirculating phase current below the predefined threshold is detected, the determining step comprises determining the at least one next driving pulse in which the phase current is no longer dropping below the predefined threshold.

A method for controlling a single coil brushless DC motor having an electrical time constant, the method comprising EHP sequences which comprise a pulse train which comprises at least two driving pulses of a same polarity, in which each driving pulse comprises:

• applying a driving signal during a torque generating period (TGP), to increase a phase current, followed by a non-torque generating period (NTGP), during which the phase current is reducing,
• monitoring the phase current during a sensing window thereby obtaining phase current information, wherein the sensing window lasts at least during a time constant, which is the electrical time constant or an approximation of the electrical time constant, if the sensing window is during the TGP, and wherein the sensing window minimally lasts until the phase current has reduced to less than half the maximum phase current which was generated during the TGP if the sensing window is during the NTGP,
• and determining parameters for the ongoing EHP, and/or for at least one next EHP sequence based on the obtained phase current information,
• wherein the sensing window is during the TGP and wherein the determining step comprises determining parameters for the ongoing EHP, and/or for at least one next EHP sequence based on the obtained phase current information by using a slope or a peak value of the phase current during the TGP.