US3775651A — Power system overcurrent protection means utilizi…

Claim 1

Independent Claim 309 words

A power system for reversibly transmitting variable voltage electric power to an electric motor, said power system comprising: a source of variable voltage electric power, regulating means coupled to said variable voltage source for controlling at least the voltage of the electric power transmitted between said variable voltage source and an electric motor connected thereto, the voltage being variable between minimum and maximum levels, current signal generating means coupled to sense actual current transmitted between said variable voltage source and an electric motor connected thereto and to generate a currenT signal proportional thereto, voltage signal generating means for generating a continuous voltage signal having distinct signal levels for instantaneously indicating the polarity of the actual output voltage of said variable voltage source, and control signal generating means coupled to said current signal generating means and said voltage signal generating means and being responsive to the current and voltage signals to generate a first control signal in response to a motoring current equal to or greater than a predetermined level and to generate a second control signal in response to a regenerative current equal to or greater than a predetermined level, said regulating means being coupled to said control signal generating means for receiving control signals therefrom, said regulating means being responsive to a first control signal to substantially instantaneously reduce the output voltage of said variable voltage source by a single step function to the minimum voltage level throughout the duration of the first control signal and being responsive to a second control signal to substantially instantaneously increase the output voltage of said variable voltage source by a single step function to the maximum voltage level throughout the duration of only the second control signal so as to thereby reduce the level of the actual current being transmitted between said variable voltage source and an electric motor connected thereto.

Claim 2

Dependent Claim 309 words

A power system for reversibly transmitting variable voltage electric power to an electric motor, said power system comprising: a source of variable voltage electric power, regulating means coupled to said variable voltage source for controlling at least the voltage of the electric power transmitted between said variable voltage source and an electric motor connected thereto, the voltage being variable between minimum and maximum levels, current signal generating means coupled to sense actual current transmitted between said variable voltage source and an electric motor connected thereto and to generate a currenT signal proportional thereto, voltage signal generating means for generating a continuous voltage signal having distinct signal levels for instantaneously indicating the polarity of the actual output voltage of said variable voltage source, and control signal generating means coupled to said current signal generating means and said voltage signal generating means and being responsive to the current and voltage signals to generate a first control signal in response to a motoring current equal to or greater than a predetermined level and to generate a second control signal in response to a regenerative current equal to or greater than a predetermined level, said regulating means being coupled to said control signal generating means for receiving control signals therefrom, said regulating means being responsive to a first control signal to substantially instantaneously reduce the output voltage of said variable voltage source by a single step function to the minimum voltage level throughout the duration of the first control signal and being responsive to a second control signal to substantially instantaneously increase the output voltage of said variable voltage source by a single step function to the maximum voltage level throughout the duration of only the second control signal so as to thereby reduce the level of the actual current being transmitted between said variable voltage source and an electric motor connected thereto.

Claim 3

Dependent Claim 57 words

A power system as defined by claim 1 in which said source of variable voltage electric power is a static power inverter adapted to be coupled between a source of d-c electric power and an a-c motor and in which said regulating means controls the fundamental output frequency of said inverter as well as the output voltage.

Claim 4

Dependent Claim 126 words

A power system as defined by claim 2 in which said inverter is a polyphase inverter having a plurality of output phases for connection to the respective phases of a polyphase a-c motor, said current signal generating means being responsive to the actual current in each of said output phases and generating a respective plurality of current signals, said voltage signal generating means generating a plurality of voltage signals each in phase with the voltage of a respective one of said output phases, and said control signal generating means being responsive to the current and voltage signals to generate a first control signal in response to a motoring current in any one of said output phases which is equal to or greater than the predetermined level.

Claim 5

Dependent Claim 91 words

A power system as defined by claim 3 in which said control signal generating means is responsive to the current and voltage signals to generate a second control signal in response to a regenerative current in any one of said output phases which is equal to or greater than the predetermined level, said control signal generating means further comprising means responsive to the simultaneous generation of first and second control signals to respond to only the first control signal and thereby reduce the output voltage of each of said input phases.

Claim 6

Dependent Claim 290 words

A power system as defined by claim 3 in which said current signal generating means comprises a plurality of current sensing means each coupled to a respective one only of said inverter output pulses and generating a current signal proportional to the actual output current of the respective output phase, and in which said control signal generating means further comprises: a plurality of overcurrent signal generating means each coupled to a respective one only of said current signal generating means for generating a first over-current signal when the actual current is equal to or greater than a fixed positive level and a second overcurrent signal when the actual current is equal to or less than a fixed negative level, a plurality of first gating means each coupled to a respective one only of said overcurrent signal generating means for receiving first and second over-current signals therefrom and to said volTage signal generating means for receiving therefrom at least one voltage signal in phase with the respective output phase, each of said first gating means being responsive to the overcurrent and voltage signals supplied thereto to generate a first output signal only when the overcurrent and voltage signals are consistent with motoring operation and to generate a second output signal only when the overcurrent and voltage signals are consistent with regenerative operation, and second gating means having a first input coupled to each of said first gating means for receiving first output signals therefrom, a second input coupled to each of said first gating means for receiving second output signals therefrom, and an output coupled to said regulating means, said second gating means being responsive to one or more first output signals to generate at said output a first control signal.

Claim 7

Dependent Claim 40 words

A power system as defined by claim 5 in which said second gating means is responsive to one or more second output signals only in the absence of first output signals to generate at said output a second control signal.

Claim 8

Dependent Claim 41 words

A power system as defined by claim 5 in which each of said overcurrent signal generating means has a first output at which the first overcurrent signal is generated and a second output at which the second overcurrent signal is generated.

Claim 9

Dependent Claim 239 words

A power system as defined by claim 7 in which each of said first gating means comprises first, second, third, and fourth logic gates each having first and second inputs and an output, means coupling said first input of each of said first and second logic gates to said first output of the respective overcurrent signal generating means, means coupling said first input of each of said third and fourth logic gates to said second output of the respective overcurrent signal generating means, means coupling said regulating means to said second input of each of said logic gates for supplying a voltage signal inphase with the voltage of the respective output phase of said inverter to said second input of said first and third logic gates and a voltage signal 180* out-of-phase with the voltage of the respective output phase of said inverter to said second input of said second and fourth logic gates, means coupling said output of each of said first and fourth logic gates to said first input of said second gating means, and means coupling said output of each of said second and third logic gates to said second input of said second gating means, said first gating means being responsive to overcurrent and voltage signals to generate first output signals at said outputs of said first and fourth logic gates and second output signals at said outputs of said second and third logic gates.

Claim 10

Dependent Claim 272 words

An a-c adjustable speed drive system comprising: a polyphase a-c motor, a polyphase inverter for changing unidirectional electric power to polyphase electric power, said conversion means including a plurality of output phases each connected to a respective phase of said motor, regulating means normally responsive to input signals including a reference signal to regulate the output voltage of said inverter within a range having minimum and maximum levels, current signal generating means coupled to sense the actual current transmitted in at least a selected one of the phase connections between said inverter and said motor and to generate a current signal proportional thereto, voltage signal generating means for generating at least one voltage signal in-phase with the voltage of said selected phase connection, and control signal generating means coupled to said current signal generating means and said voltage signal generating means and being responsive to the current and voltage signals to generate a first control signal in response to a motoring current equal to or greater than a predetermined level and to generate a second control signal in response to a regenerative current equal to or greater than a predetermined leveL, said regulating means being coupled to said control signal generating means for receiving control signals therefrom, said regulating means being responsive to a first control signal to substantially instantaneously reduce the output voltage by a single step function to the minimum level of said range and being responsive to a second control signal only in the absence of a first control signal to substantially instantaneously increase the output voltage by a single step function to the maximum level of said range.

Claim 11

Dependent Claim 272 words

An a-c adjustable speed drive system comprising: a polyphase a-c motor, a polyphase inverter for changing unidirectional electric power to polyphase electric power, said conversion means including a plurality of output phases each connected to a respective phase of said motor, regulating means normally responsive to input signals including a reference signal to regulate the output voltage of said inverter within a range having minimum and maximum levels, current signal generating means coupled to sense the actual current transmitted in at least a selected one of the phase connections between said inverter and said motor and to generate a current signal proportional thereto, voltage signal generating means for generating at least one voltage signal in-phase with the voltage of said selected phase connection, and control signal generating means coupled to said current signal generating means and said voltage signal generating means and being responsive to the current and voltage signals to generate a first control signal in response to a motoring current equal to or greater than a predetermined level and to generate a second control signal in response to a regenerative current equal to or greater than a predetermined leveL, said regulating means being coupled to said control signal generating means for receiving control signals therefrom, said regulating means being responsive to a first control signal to substantially instantaneously reduce the output voltage by a single step function to the minimum level of said range and being responsive to a second control signal only in the absence of a first control signal to substantially instantaneously increase the output voltage by a single step function to the maximum level of said range.

Claim 12

Dependent Claim 38 words

An a-c adjustable speed drive system as defined by claim 9 in which said regulating means also regulates the output frequency of said inverter, the output frequency being regulated substantially independently of the first and second control signals.

Claim 13

Dependent Claim 110 words

An a-c adjustable speed drive system as defined by claim 9 in which said current signal generating means is responsive to the actual current in each of said output phases and generating a respective plurality of current signals, in which said voltage signal generating means generates a plurality of voltage signals each in phase with the voltage of a respective one of said output phases, and in which said control signal generating means is responsive to the current and voltage signals to generate a first control signal in response to a motoring current in any one of said output phases which is equal to or greater than the predetermined level.

Claim 14

Dependent Claim 96 words

An a-c adjustable speed drive system as defined by claim 11 in which said control signal generating means is responsive to the current and voltage signals to generate a second control signal in response to a regenerative current in any one of said output phases which is equal to or greater than the predetermined level, said control signal generating means further comprising means responsive to the simultaneous generating of first and second control signals to respond to only the first control signal so as to thereby reduce the output voltage of each of said output phases.

Claim 15

Dependent Claim 293 words

An a-c adjustable speed drive system as defined by claim 12 in which said current signal generating means comprises a plurality of current sensing means each coupled to a respective one only of said inverter output pulses and generating a current signal proportional to the actual output current of the respective output phase, and in which said control signal generating means further comprises: a plurality of overcurrent signal generating means each coupled to a respective one only of said current signal generating means for generating a first overcurrent signal when the actual current is equal to or greater than a fixed positive level and a second overcurrent signal when the actual current is equal to or less than a fixed negative level, a plurality of first gating means each coupled to a respective one only of said overcurrent signal generating means for receiving first and second overcurrent signals therefrom and to said voltage signal generating means for receiving therefrom at least one voltage signal in phase with the respective output phase, each of said first gating means being responsive to the overcurrent and voltage signals supplied thereto to generate a first output signal only when the overcurrent and voltage signals are consistent with motoring operation and to generate a second output signal only when the overcurrent and voltage signals are consistent with regenerative operation, and second gating means having a first input coupled to each of said first gating means for receiving first output signals therefrom, a second input coupled to each of said first gating means for receiving second output signals therefrom, and an output coupled to said regulating means, said second gating means being responsive to one or more first output signals to generate at said output a first control signal.

Claim 16

Dependent Claim 43 words

An a-c adjustable speed drive system as defined by claim 13 in which said second gating means is responsive to one or more second output signals only in The absence of first output signals to generate at said output a second control signal.

Claim 17

Dependent Claim 276 words

An a-c adjustable speed drive system as defined by claim 14 in which each of said overcurrent signal generating means has a first output at which the first overcurrent signal is generated and a second output at which the second overcurrent signal is generated and in which each of said first gating means comprises first, second, third, and fourth logic gates each having first and second inputs and an output, means coupling said first input of each of said first and second logic gates to said first output of the respective overcurrent signal generating means, means coupling said first input of each of said third and fourth logic gates to said second output of the respective over-current signal generating means, means coupling said regulating means to said second input of each of said logic gates for supplying a voltage signal in-phase with the voltage of the respective output phases of said inverter to said second input of said first and third logic gates and a voltage signal 180* out-of-phase with the voltage of the respective output phase of said inverter to said second input of said second and fourth logic gates, means coupling said output of each of said first and fourth logic gates to said first input of said second gating means, and means coupling said output of each of said second and third logic gates to said second input of said second gating means, said first gating means being responsive to overcurrent and voltage signals to generate first output signals at said outputs of said first and fourth logic gates and second output signals at said outputs of said second and third logic gates.

Claim 18

Dependent Claim 21 words

An a-c adjustable speed drive system as defined by claim 15 in which said second gating means comprises a logic network.

Claim 19

Dependent Claim 91 words

An a-c adjustable speed drive system as defined by claim 16 in which said second gating means comprises first and second logic gates each having a single output and in which said first and second inputs of said second gating means comprise selected inputs of said first and second logic gates, respectively, and said output of said second gating means comprises the output of said first logic gate, said second gating means further comprising means coupling the output of said second logic gate and an input of said first logic gate.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1976-11-26	1977-05-28	1977-11-27	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1980-11-26	1981-05-28	1981-11-27	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1984-11-26	1985-05-28	1985-11-27	$7700.00	Window Closed / Lapsed

Power system overcurrent protection means utilizing voltage adjustment

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag