Chopper control system

Claim 2

A chopper control system having a chopper for controlling a current supplied from a d.c. power supply to a load, and means for controlling said chopper, wherein said chopper control means comprises an oscillator and a magnetic phase shifter, and said magnetic phase shifter includes a saturable core, a control winding wound around said core to be applied with a control instruction signal, and an output winding wound around said core to be applied with the output of said oscillator, and further comprising means for deriving a ''''negation'''' of the output of said maGnetic phase shifter, and means for actuating said chopper in response to said ''''negation'''' of the output.

Claim 3

A chopper control system as claimed in claim 1, wherein said ''''not'''' output deriving means comprises a first differentiating means for differentiating the output of said oscillator and a second differentiating means for differentiating the output of said output winding, and said chopper actuating means comprises means for turning on said chopper in response to the appearance of the output from said first differentiating means and turning off said chopper in response to the appearance of the output from said second differentiating means.

Claim 4

A chopper control system as claimed in claim 1, wherein said ''''not'''' output deriving means comprises means for removing a portion of the output of said oscillator during the period of time in which said magnetic phase shifter delivers its output.

Claim 5

A chopper control system as claimed in claim 3, wherein said ''''not'''' output deriving means comprises conducting angle limiting means for cutting the rising portion of the output of said oscillator for a predetermined period of time.

Claim 6

A chopper control system comprising a d.c. power source, a load, a chopper for controlling a load current supplied from said d.c. power source to said load, said chopper including at least a main thyristor for permitting the load current to flow therethrough and an auxiliary thyristor for turning-off said main thyristor, and chopper control means for controlling the output of said chopper by applying a chopper-on signal and a chopper-off signal to said main thyristor and said auxiliary thyristor respectively, said chopper control means including: an oscillator which oscillates at a fixed frequency, the period of oscillation of said oscillator determining a period for controlling said chopper; a magnetic phase shifter for adjusting the ratio of the chopper-on period to the chopper-off period in said chopper control period, said magnetic phase shifter including a saturable core, a control winding wound on said core for receiving a control instruction, an output winding wound on said core for receiving the output of said oscillator, and a feedback winding wound on said core for feeding back a detected value corresponding to said load current, thereby adjusting said ratio of the chopper-on period to the chopper-off period in response to deviations of said detected value from said control instruction; and means for delivering one of the outputs of said oscillator and said magnetic phase shifter as the chopper-on signal and the other as the chopper-off signal.

Claim 7

A chopper control system comprising a d.c. power source, a load, a chopper for controlling a load current supplied from said d.c. power source to said load, said chopper including at least a main thyristor for permitting the load current to flow therethrough and an auxiliary thyristor for turning-off said main thyristor, and chopper control means for controlling the output of said chopper by applying a chopper-on signal and a chopper-off signal to said main thyristor and said auxiliary thyristor respectively, said chopper control means including: an oscillator which oscillates at a fixed frequency, the period of oscillation of said oscillator determining a period for controlling said chopper; a magnetic phase shifter for adjusting the ratio of the chopper-on period to the chopper-off period in said chopper control period, said magnetic phase shifter including a saturable core, a control winding wound on said core for receiving a control instruction, an output winding wound on said core for receiving the output of said oscillator, and a feedback winding wound on said core for feeding back a detected value corresponding to said load current, thereby adjusting said ratio of the chopper-on period to the chopper-off period in response to deviations of said detected value from said control instruction; and means for delivering one of the outputs of said oscillator and said magnetic phase shifter as the chopper-on signal and the other as the chopper-off signal.

Claim 8

A chopper control system as claimed in claim 5, wherein said load includes a d.c. series motor and is provided with a first diode connected inversely parallel with the series circuit of the armature and field coil of said motor, a second diode connected inversely parallel with said armature, and reversers for changing over the polarity of said field coil.

Claim 9

A chopper control system according to claim 5, wherein said oscillator is a rectangular waveform generator and said chopper-on and chopper-off signal delivering means includes a differentiating circuit, whereby the output of said magnetic phase shifter is delivered as the chopper-on signal and the output of said rectangular waveform generator is delivered through said differentiating circuit as the chopper-off signal.

Claim 10

A chopper control system according to claim 5, wherein said oscillator is a rectangular waveform generator and said chopper-on and chopper-off signal delivering means includes a differentiating circuit, whereby the output of said magnetic phase shifter is delivered as the chopper-off signal and the output of said rectangular waveform generator is delivered through said differentiating circuit as the chopper-on signal.

Claim 11

A chopper control system according to claim 5, wherein a short-circuit winding is provided on said core, said short-circuit winding being short-circuitEd through an impedance element.