Control device for brushless motor and control method therefor

A control device for a brushless DC motor including a rotor having a magnet field constituted by a plurality of magnetic poles and a stator including driving coils for a plurality of phases, comprising:

• a position detector for detecting positional relationships between said driving coils for said plurality of phases and said plurality of magnetic poles to generate at least one position detection signal;
• a rotation control section for generating at least one driving signal based on said position detection signal;
• said rotation control section including a latch means for generating said driving signal based on said position detection signal while it is fed with a rotation command and holding, when it is fed with a stop command, said driving signal at a level or polarity thereof obtained at the time of feeding of the stop command thereto;
• and
• a motor driving section fed with said driving signal and flowing an excitation current through said driving coil for at least one of said plurality of phases determined depending on a level or polarity of said driving signal fed thereto.

A control device for a brushless motor including a rotor having a magnet field and a stator including driving coils for a plurality of phases, comprising:

• a position detector arranged on a side of said stator to detect a position of said rotor to generate at least one position detection signal;
• a switch circuit including a plurality of switch elements for operating an excitation current flowed through each of said driving coils for said plurality of phases;
• a distributor for determining the driving coil for at least one of said plurality of phases which is to be excited for rotating said rotor depending on said position detection signal;
• said distributor generating a plurality of on-off indication signals indicating whether said switch elements of said switch circuit should be turned on or turned off so that the excitation current is flowed through said driving coil determined;
• and
• a rotation control section for controlling said switch elements of said switch circuit depending on a rotation command and a stop command;
• said rotation control section including a latch means for generating a plurality of trigger signals for operating the switch elements which are indicated to be turned on or turned off by said on-off indication signals while it is fed with the rotation command and holding, when it is fed with the stop command, said trigger signals fed to each of said switch elements of said switch circuit in a state thereof obtained at the time of feeding of the stop command thereto.

A control device for a brushless motor including a rotor having a magnet field and a stator including driving coils for a plurality of phases, comprising:

• a position detector for detecting a position of said rotor to generate at least one position detection signal;
• a switch circuit including a plurality of switch elements for operating an excitation current flowed through each of said driving coils for said plurality of phases;
• a distributor for determining the driving coil for at least one of said plurality of phases which is to be excited for rotating said rotor depending on said position detection signal;
• said distributor generating a plurality of on-off indication signals indicating whether said switch elements of said switch circuit should be turned on or turned off so that the excitation current is flowed through said driving coil determined;
• and
• a rotation control section for controlling said switch elements of said switch circuit depending on a rotation command and a stop command;
• said rotation control section including a plurality of trigger circuits for generating trigger signals for operating said switch elements which are indicated to be turned on or turned off by said on-off indication signals while the rotation command is fed thereto and holding, when the stop command is fed thereto, all the trigger signals fed to said switch elements of said switch circuit in a state-thereof obtained at the time of feeding of the stop command thereto.

A method for controlling a brushless motor including a rotor having a magnet field and a stator including driving coils for a plurality of phases, comprising the steps of;

• detecting magnetic poles of the magnet field on a side of said stator by means of a position detector to generate signals corresponding to polarities of the magnetic poles being detected;
• determining the driving coil for at least one of said phases through which an excitation current is flowed depending on said signal generated from said position detector and flowing the excitation current through said driving coil determined, to thereby continue rotation of the rotor while a rotation command is generated;
• continuing to flow said excitation current through said driving coil to stop the rotor when a stop command is generated;
• detecting a stop position of the rotor after the rotor is stopped;
• and
• selecting, when said stop position detected is deviated from a set position, at least one of said phases necessary for rotating the rotor to said set position as an excitation phase to keep the excitation coil for said excitation phase excited, to thereby rotate the rotor to the set position.