Inverter with controlled rectifiers and a regulable direct voltage supply

Claim 2

A regulated voltage supply system comprising an inverter including controlled rectifiers; a regulated direct voltage supply means having an input to which in use a fixed direct voltage is applied and an output connected to said inverter, said supply means comprising an on/off switchable element connected to said input of the supply means, a filter connected between said switchable element and said output of the supply means, and a control circuit connected to said output of the supply means and to said switchable elemEnt for supplying first control pulses to said switchable element; and a pulse generator connected to said output of the supply means for deriving second control pulses to control said rectifiers in the inverter; wherein said control circuit comprises a step regulator formed by a high-gain amplifier having negative and positive feedback paths, the negative feedback path effecting a time-delay and comprising a first resistor and a non-linear network formed by a first diode and a second resistor connected in series across said first resistor and the positive feedback path resulting in the production of an oscillation which controls both the frequency and the width of the first control pulses when the voltage at said output of the supply means changes.

Claim 3

A system according to claim 1 wherein said amplifier is a sum-and-difference amplifier having two inputs and an output, the output of said amplifier being connected via said negative feedback path to one of said inputs of said amplifier, and via said positive feedback path to the other of said inputs of said amplifier.

Claim 4

A system according to claim 2 wherein said amplifier has first and second input terminals and first and second output terminals, and comprises first and second junction transistors, a resistor connected to the collector of the second transistor, a third transistor which is controlled by the voltage-drop across said collector resistor, a neutral lead, and two supply leads which carry a higher and lower potential respectively than said neutral lead which connects said first input terminal of said amplifier to said first output terminal of said amplifier, said second output terminal of said amplifier and said two feedback paths being connected to the collector of said third transistor.

Claim 5

A system according to claim 3 wherein said step regulator further comprises first and second voltage dividers having respective tapping points, and said second output terminal of said amplifier is connected by way of said first voltage divider to said first input terminal of said amplifier, and by way of said second voltage divider to said second input terminal of said amplifier, the bases of said first and second transistors being respectively connected to said tapping points of the voltage dividers.

Claim 6

A system according to claim 1 wherein said negative feedback path comprises a first RC-network formed by said first resistor and a capacitor.

Claim 7

A system according to claim 5 wherein said step regulator further comprises a second RC-network of the same order of magnitude as said first RC-network connected between said output of the supply means and said amplifier.

Claim 8

A system according to claim 1 wherein a diode is connected between said step regulator and said switchable element to limit the voltage supplied to the switchable element to negative values.

Claim 9

A regulated voltage supply system comprising an inverter including controlled rectifiers; a regulated direct voltage supply means having an input to which in use a fixed direct voltage is applied and an output connected to said inverter, said supply means comprising an on/off switchable element connected to said input of the supply means, a filter connected between said switchable element and said output of the supply means, and a control circuit connected to said output of the supply means and to said switchable element for supplying first control pulses to said switchable element; and a pulse generator connected to said output of the supply means for deriving second control pulses to control said rectifiers in the inverter; wherein said control circuit comprises a step regulator formed by a high-gain amplifier having negative and positive feedback paths, the negative feedback path effecting a time-delay and comprising a first resistor and a non-linear network formed by a first diode and a second resistor connected in series across said first resistor, and the positive feedback path resulting in the production of an oscillation which controls both the frequency and the width of the first control pulses when the voltage at said output of the supply means changes, the effect of said positive feedback path having a lesser effect than said negative feedback path, said amplifier being a sum-and-difference amplifier having two inputs and an output, the output of said amplifier being connected via said negative feedback path to one of said inputs of said amplifier, and via said positive feedback path to the other of said inputs of said amplifier.

Claim 10

A regulated voltage supply system comprising an inverter including controlled rectifiers; a regulated direct voltage supply means having an input to which in use a fixed direct voltage is applied and an output connected to said inverter, said supply means comprising an on/off switchable element connected to said input of the supply means, a filter connected between said switchable element and said output of the supply means, and a control circuit connected to said output of the supply means and to said switchable element for supplying first control pulses to said switchable element; and a pulse generator connected to said output of the supply means for deriving second control pulses to control said rectifiers in the inverter; wherein said control circuit comprises a step regulator formed by a high-gain amplifier having negative and positive feedback paths, the negative feedback path effecting a time-delay and comprising a first resistor and a non-linear network formed by a first diode and a second resistor connected in series across said first resistor, and the positive feedback path resulting in the production of an oscillation which controls both the frequency and the width of the first control pulses when the voltage at said output of the supply means changes, the effect of said positive feedback path having a lesser effect than said negative feedback path, said amplifier being a sum-and-difference amplifier having two inputs and an output, the output of said amplifier being connected via said negative feedback path to one of said inputs of said amplifier, and via said positive feedback path to the other of said inputs of said amplifier.