Speed control system for hall effect motors

Claim 2

A speed control system for a Hall effect motor, said motor comprising a resolver element provided with Hall generators having respective outputs, a motor element provided with windings respectively associated with said Hall generators, said windings having respective first and second terminals, and feeding circuits respectively associated with said windings and said Hall generators for supplying to their associated windings rectangular waveform signals whose phases are respectively determined by the output signals of their associated Hall generators, said speedcontrol system comprising : i. a comparator circuit having a first input for receiving a first signal, a second input for receiving a reference signal, and an output for delivering a third signal which is a function of the frequency of said first signal, said comparator circuit having its first input coupled to the output of one of said Hall generators for receiving a signal whose frequency is a function of the speed of said motor and whose amplitude is independent of said speed, and ii. switching devices, respectively associated with said feeding circuits and controlled by said comparator circuit for cutting the supply to said windings when the frequency of said first signal exceeds a threshold frequency which is a function of said reference signal.

Claim 3

A control system as claimed in claim 1, wherein each of said feeding circuits comprises : a high-gain amplifier having an input connected to the output of the associated Hall generator and an output coupled to said first input of said comparator circuit ; a direct current voltage source having first and second terminals ; a first channel connecting the first terminal of the asosciated winding to the first terminal of said source and the second terminal of said associated winding to the second terminal of said source ; a second channel connecting said second terminal of said associated winding to the first terminal of said source and the first terminal of said associated winding to the second terminal of said source ; a two-state circuit controlled by the output of said amplifier for alternately (i) blocking said first channel and making said second channel conductive and (ii) vice-versa when the frequency of said first signal does not exceed said threshold frequency ; and wherein each switching device associated with a feeding circuit is an auxiliary control circuit for simultaneously blocking said two channels independently of the state of said two-state circuit when said frequency of said first signal exceeds said threshold frequency.

Claim 4

A control system as claimed in claim 1, wherein said comparator essentially comprises : a frequency-voltage converter having an input which is said first input of the comparator circuit and an output ; a voltage comparator having a first input connected to the output of said converter and a second input ; and means for applying to said second input of said voltage comparator said reference signal under the form of a reference voltage.

Claim 5

A control system as claimed in claim 1, wherein said comparator circuit comprises two frequency-voltage converters, having respective inputs which are said two inputs of the comparator circuit and respective outputs, and a differential amplifier, having two inputs which are respectively connected to the outputs of said two converters, and an output.

Claim 6

A control system as claimed in claim 1, wherein said comparator circuit comprises a terminal two-state element, in order to produce a signal of a first level or a second level, depending upon whether the frequency of said first signal exceeds or does not exceed said threshold frequency.

Claim 7

A speed control system for a Hall effect motor, said motor comprising a resolver element provided with Hall generators having respective outputs, a motor element provided with windings respectively associated with said Hall generators, said windings having respective first and second terminals, and feeding circuits respectively associated with said windings and said Hall generators for supplying to their associated windings rectangular waveform signals whose phases are respectively determined by the output signals of their associated Hall generators, said speed-control system comprising: i. a comparator circuit having a first input for receiving a first signal, a second input for receiving a reference signal, and an output for delivering a third signal which is a function of the frequency of said first signal, said comparator circuit having its first input coupled to one of said Hall generators for receiving a signal whose frequency is a function of the speed of said motor and whose amplitude is independent of said speed, said comparator circuit comprising two frequency-voltage converters having respective inputs which are said two inputs of the comparator circuit and respective outputs, a differential amplifier having two inputs which are respectively connected to the outputs of said two converters, and an output, a phase comparator having two inputs respectively connected to said two inputs of said comparator circuit and an output, a further amplifier having an input connected both to said output of said differential amplifier and to said output of said phase comparator and an output, a two-state element controlled by said further amplifier, said two-state element having an output which is said output of said comparator circuit, and an auxiliary device for preventing said differential amplifier and said phase comparator from simultaneously affecting the voltage at said input of said further amplifier; and ii. switching devices, respectively associated with said feeding circuits and controlled by said comparator circuit for cutting the supply to said windings when the frequency of said first signal exceeds a threshold frequency which is a function of said reference signal.

Claim 8

A speed control system for a Hall effect motor, said motor comprising a resolver element provided with Hall generators having respective outputs, a motor element provided with windings respectively associated with said Hall generators, said windings having respective first and second terminals, and feeding circuits respectively associated with said windings and said Hall generators for supplying to their associated windings rectangular waveform signals whose phases are respectively determined by the output signals of their associated Hall generators, said speed-control system comprising: i. a comparator circuit having a first input for receiving a first signal, a second input for receiving a reference signal, and an output for delivering a third signal which is a function of the frequency of said first signal, said comparator circuit having its first input coupled to one of said Hall generators for receiving a signal whose frequency is a function of the speed of said motor and whose amplitude is independent of said speed, said comparator circuit comprising two frequency-voltage converters having respective inputs which are said two inputs of the comparator circuit and respective outputs, a differential amplifier having two inputs which are respectively connected to the outputs of said two converters, and an output, a phase comparator having two inputs respectively connected to said two inputs of said comparator circuit and an output, a further amplifier having an input connected both to said output of said differential amplifier and to said output of said phase comparator and an output, a two-state element controlled by said further amplifier, said two-state element having an output which is said output of said comparator circuit, and an auxiliary device for preventing said differential amplifier and said phase comparator from simultaneously affecting the voltage at said input of said further amplifier; and ii. switching devices, respectively associated with said feeding circuits and controlled by said comparator circuit for cutting the supply to said windings when the frequency of said first signal exceeds a threshold frequency which is a function of said reference signal.

Claim 9

A control system as claimed in claim 6, wherein said phase comparator has a high output impedance and wherein said auxiliary device is formed by two Zener diodes connected in opposite directions between said output of said differential amplifier and said input of said further amplifier.