Ng comprising a plurality of component windings brushless dc motor having a permanent magnet rotor and a stator windi

Claim 2

A brushless DC motor having a permanent magnet rotor and a stator winding comprising a plurality of component windings, a DC voltage source having a first positive terminal and a second negative terminal, a plurality of power transistors each having emitter, collector and base electrodes, one end of each of the component windings being in star connection with the corresponding end of the others of said component windings and being connected to the first terminal of the DC voltage source and the other end of each of said component windings being connected in series with a corresponding one of the power transistors, a common emitter resistor, the emitter electrode of each of the power transistors being connected to the second terminal of the DC voltage source via the common emitter resistor, said brushless DC motor comprising continuously adjustable control means for controlling the power transistors in dependence upon the position of the permanent magnet rotor, said control means comprising a control member having an output coupled to the power transistors and a control input, and current regulating circuit means having an output connected to the input of the control member, said current regulating circuit means having an actual value derived from a current-proportional voltage derived from the common emitter resistor and a datum value determined from outside said current regulating circuit means.

Claim 3

A brushless DC motor as claimed in claim 1, wherein the current regulating circuit means includes means for deriving the datum value thereof from the rotary speed of the rotor.

Claim 4

A brushless DC motor as claimed in claim 2, wherein the current regulating circuit means includes means for limiting the datum value thereof to a maximum.

Claim 5

A brushless DC motor as claimed in claim 3, wherein the current regulating circuit means includes means for switching off the datum value when the maximum thereof lasts longer than a predetermined period of time.

Claim 6

A brushless DC motor having a permanent magnet rotor and a stator winding comprising a plurality of component windings, a DC voltage source having a first positive terminal and a second negative terminal, a plurality of power transistor each having emitter, collector and base electrodes, one end of each of the component windings being in star connection with the corresponding end of the others of said component windings and being connected to the first terminal of the DC voltage source and the other end of each of said component windings being connected in series with a corresponding one of the power transistors, a common emitter resistor, the emitter electrode of each of the power transistors being connected to the second terminal of the DC voltage source via the common emitter resistor, said brushless DC motor comprising continuously adjustable control means for controlling the power transistors in dependence upon the position of the permanent magnet rotor, said control means comprising a control member having an output coupled to the power transistors and a control input, the control member comprising a control transistor having emitter, collector and base electrodes, and current regulating circuit means including means for deriving the datum value thereof from the rotary speed of the rotor and means for limiting the datum value thereof to a maximum and having an output connected to the input of the control member, said current regulating circuit means having an actual value derived from a currenT-proportional voltage derived from the common emitter resistor and a datum value determined from outside said current regulating circuit means, the current regulating circuit means comprising a first collector resistor, a Zener diode, a resistor connected in series with the Zener diode between the first and second terminals of the DC voltage supply, a first regulating transistor having a collector electrode connected to the base electrode of the control transistor and connected to the first terminal of the DC voltage source via the first collector resistor, an emitter electrode connected to a common point in the connection between the Zener diode and the resistor and a base electrode, a base resistor, a first emitter resistor, a second collector resistor, a second regulating transistor having a base electrode directly connected to the base electrode of the first regulating transistor and connected to the common resistor via the base resistor and to the second terminal of the DC voltage source via the first emitter resistor, and emitter and collector electrodes, a second collector resistor, a third regulating transistor having a collector electrode connected to the collector electrode of the second regulating transistor via the second collector resistor, an emitter electrode connected to the first terminal of the DC voltage source and a base electrode, and means for controlling the third regulating transistor in accordance with the rotary speed of the permanent magnet rotor.

Claim 7

A brushless DC motor having a permanent magnet rotor and a stator winding comprising a plurality of component windings, a DC voltage source having a first positive terminal and a second negative terminal, a plurality of power transistor each having emitter, collector and base electrodes, one end of each of the component windings being in star connection with the corresponding end of the others of said component windings and being connected to the first terminal of the DC voltage source and the other end of each of said component windings being connected in series with a corresponding one of the power transistors, a common emitter resistor, the emitter electrode of each of the power transistors being connected to the second terminal of the DC voltage source via the common emitter resistor, said brushless DC motor comprising continuously adjustable control means for controlling the power transistors in dependence upon the position of the permanent magnet rotor, said control means comprising a control member having an output coupled to the power transistors and a control input, the control member comprising a control transistor having emitter, collector and base electrodes, and current regulating circuit means including means for deriving the datum value thereof from the rotary speed of the rotor and means for limiting the datum value thereof to a maximum and having an output connected to the input of the control member, said current regulating circuit means having an actual value derived from a currenT-proportional voltage derived from the common emitter resistor and a datum value determined from outside said current regulating circuit means, the current regulating circuit means comprising a first collector resistor, a Zener diode, a resistor connected in series with the Zener diode between the first and second terminals of the DC voltage supply, a first regulating transistor having a collector electrode connected to the base electrode of the control transistor and connected to the first terminal of the DC voltage source via the first collector resistor, an emitter electrode connected to a common point in the connection between the Zener diode and the resistor and a base electrode, a base resistor, a first emitter resistor, a second collector resistor, a second regulating transistor having a base electrode directly connected to the base electrode of the first regulating transistor and connected to the common resistor via the base resistor and to the second terminal of the DC voltage source via the first emitter resistor, and emitter and collector electrodes, a second collector resistor, a third regulating transistor having a collector electrode connected to the collector electrode of the second regulating transistor via the second collector resistor, an emitter electrode connected to the first terminal of the DC voltage source and a base electrode, and means for controlling the third regulating transistor in accordance with the rotary speed of the permanent magnet rotor.

Claim 8

A brushless DC motor as claimed in claim 5, wherein the third regulating transistor has a base-emitter path and the current regulating circuit means further comprises a terminal resistor, a collector resistor, a switching transistor having emitter and collector electrodes, a base electrode connected to the first terminal of the DC voltage source via the terminal resistor, and an emitter-collector path connected in parallel with the base-emitter path of the third regulating transistor, and a self-holding circuit comprising another base resistor, a voltage divider having one end connected in parallel with the common emitter resistor to the second terminal of the DC voltage source and a tap, a delay capacitor, and a delay transistor having a base electrode connected to the tap of the voltage divider via the other base resistor and connected to the second terminal of the DC voltage source via the delay capacitor, emitter and collector electrodes and an emitter-collector path connected between the second terminal of the DC voltage source and the base electrode of the switching transistor via the collector resistor.

Claim 9

A brushless DC motor as claimed in claim 6, wherein the collector resistor is a variable resistor having a tap and the self-holding circuit further comprises a second emitter resistor and a self-holding transistor complementing the delay transistor and having a base electrode connected to the tap of the collector resistor, an emitter electrode connected to the base electrode of the switching transistor via the second emitter resistor and a collector electrode connected to the base electrode of the delay transistor.

Claim 10

A brushless DC motor as claimed in claim 7, wherein the self-holding circuit further comprises a control terminal connected to the tap of the collector resistor.