Variable mode feedback control system

Claim 2

A feedback control system, comprising: amplifier means for supplying controlled power to a load, said amplifier means being normally operable in a stable, substantially linear mode; sensing means connected to said load for sensing particular load parameters; and controlled feedback means for causing said amplifier means to operate in an oscillatory mode by means of phase shifts within said amplifier means in response to predetermined conditions of said load parameters, said controlled feedback means being connected between said sensing means and the input to said amplifier means for applying a signal from said sensing means to said input to said amplifier means.

Claim 3

A feedback control system as defined in claim 1, wherein: said oscillatory mode of said amplifier means defines a pulse-width modulation mode for said amplifier means.

Claim 4

A feedback amplifier control system as defined in claim 2, wherein: only one of said particular load parameters controls the pulse-width modulation mode of said amplifier means through said controlled feedback means.

Claim 5

A feedback control system as defined in claim 3, wherein: said one particular load parameter is the primary load parameter controlled by said amplifier means.

Claim 6

A feedback control system, comprising: amplifier means for supplying controlled power to a load, said amplifier means being normally operable in a stable, substantially linear mode; sensing means connected to said load for sensing particular load parameters; and controlled feedback means for causing said amplifier means to operate in an oscillatory mode in response to predetermined conditions of said load parameters, said controlled feedback means being connected between said sensing means and the input to said amplifier means for applying a signal from said sensing means to said input to said amplifier means, said controlled feedback means including phase shift means for shifting the phase of the signal applied to said input to said amplifier means so that said signal is in the proper phase to cause said amplifier means to operate in said oscillatory mode.

Claim 7

A feedback control system, comprising: amplifier means for supplying controlled power to a load, said amplifier means being normally operable in a stable, substantially linear mode; sensing means connected to said load for sensing particular load parameters; and controlled feedback means for causing said amplifier means to operate in an oscillatory mode in response to predetermined conditions of said load parameters, said controlled feedback means being connected between said sensing means and the input to said amplifier means for applying a signal from said sensing means to said input to said amplifier means, said controlled feedback means including phase shift means for shifting the phase of the signal applied to said input to said amplifier means so that said signal is in the proper phase to cause said amplifier means to operate in said oscillatory mode.

Claim 8

A feedback control system as defined in claim 5, wherein: said signal is in the proper phase to cause said amplifier means to operate in said oscillatory mode over a preselected range of frequencies determined at least in part by said phase shift means.

Claim 9

A feedback control system as defined in claim 6, wherein: said oscillatory mode of said amplifier means defines a pulse-width modulation mode for said amplifier means.

Claim 10

A feedback amplifier control system as defined in claim 7, wherein: only one of said particular load parameters controls the pulse-width modulation mode of said amplifier means through said controlled feedback means.

Claim 11

A feedback control system as defined in claim 8, wherein: said one particular load parameter is the primary load parameter controlled by said amplifier means.

Claim 12

A feedbaCk control system, comprising: amplifier means for supplying controlled power to a load, said amplifier means being normally operable in a stable, substantially linear mode, said amplifier means mainly controlling one particular load parameter; sensing means connected to said load for sensing particular load parameters, said sensing means generating a signal indicative of the condition of said one particular load parameter; controlled feedback means for causing said amplifier means to operate in an oscillatory mode in response to predetermined conditions of said load parameters, said controlled feedback means being connected between said sensing means and the input to said amplifier means for applying a signal from said sensing means to said input to said amplifier means, said controlled feedback means including a series circuit with a gate between the source of said signal and said input to said amplifier means, said controlled feedback means further including an enabling network connected to said gate for enabling said gate in response to predetermined conditions of others of said particular load parameters.

Claim 13

A feedbaCk control system, comprising: amplifier means for supplying controlled power to a load, said amplifier means being normally operable in a stable, substantially linear mode, said amplifier means mainly controlling one particular load parameter; sensing means connected to said load for sensing particular load parameters, said sensing means generating a signal indicative of the condition of said one particular load parameter; controlled feedback means for causing said amplifier means to operate in an oscillatory mode in response to predetermined conditions of said load parameters, said controlled feedback means being connected between said sensing means and the input to said amplifier means for applying a signal from said sensing means to said input to said amplifier means, said controlled feedback means including a series circuit with a gate between the source of said signal and said input to said amplifier means, said controlled feedback means further including an enabling network connected to said gate for enabling said gate in response to predetermined conditions of others of said particular load parameters.

Claim 14

A feedback control system as defined in claim 10, wherein: said oscillatory mode of said amplifier means defines a pulse-width modulation mode for said amplifier means.

Claim 15

A feedback amplifier control system as defined in claim 11, wherein: only one of said particular load parameters controls the pulse-width modulation mode of said amplifier means through said controlled feedback means.

Claim 16

A feedback control system as defined in claim 12, wherein: said controlled feedback means includes phase shift means for shifting the phase of the signal applied to said input to said amplifier means so that said signal is in the proper phase to cause said amplifier means to operate in said oscillatory mode.

Claim 17

A feedback control system as defined in claim 13, wherein: said signal is in the proper phase to cause said amplifier means to operate in said oscillatory mode over a preselected range of frequencies determined at least in part by said phase shift means.

Claim 18

A feedback control system comprising: power amplifier means for supplying controlled power to a load, said power amplifier means having an input and an output; a load having a moving inductance type driven element, the output of said amplifier means being connected to said load and the current through said load lagging in phase behind the voltage across said load; operational amplifier means for driving said power amplifier means, the output of said operational amplifier means being connected to the input of said power amplifier means through a first phase lag electrical network, the output of said operational amplifier means being further connected to the input of said operational amplifier means through a second phase lag electrical network, the input to said operational amplifier means defining a summing point; sensing means connected to said load for sensing particular load parameters, including a means for sensing load current; feedback means connected between said sensing means and said summing point for stabilizing said system to operate in a substantially linear mode; and controlled feedback means for causing said system to operate in an oscillatory mode, said controlled feedback means being connected between said load current sensing means and said summing point, said controlled feedback means being enabled by a predetermined condition of a preselected particular parameter of said load.

Claim 19

A feedback control system comprising: power amplifier means for supplying controlled power to a load, said power amplifier means having an input and an output; a load having a moving inductance type driven element, the output of said amplifier means being connected to said load and the current through said load lagging in phase behind the voltage across said load; operational amplifier means for driving said power amplifier means, the output of said operational amplifier means being connected to the input of said power amplifier means through a first phase lag electrical network, the output of said operational amplifier means being further connected to the input of said operational amplifier means through a second phase lag electrical network, the input to said operational amplifier means defining a summing point; sensing means connected to said load for sensing particular load parameters, including a means for sensing load current; feedback means connected between said sensing means and said summing point for stabilizing said system to operate in a substantially linear mode; and controlled feedback means for causing said system to operate in an oscillatory mode, said controlled feedback means being connected between said load current sensing means and said summing point, said controlled feedback means being enabled by a predetermined condition of a preselected particular parameter of said load.

Claim 20

A feedback control system as defined in claim 15, wherein: said oscillatory mode of said system defines a pulse-width modulation mode for said power amplifier means.

Claim 21

A feedback control system as defined in claim 15, wherein: the sum of the phase lags of said load and said first and second phase lag electrical networks is such that the feedback signal due to the load current applied to said input of said power amplifIer means through said controlled feedback means is positive over a preselected range of frequencies to produce an oscillatory condition in said power amplifier means defining a pulse-width modulation mode for said system when said controlled feedback means is enabled.

Claim 22

A feedback control system as defined in claim 17, wherein: the frequency range of oscillations of said power amplifier means is sufficiently higher than the bandwidth characteristics of said feedback control system so that the current through said load is substantially averaged; and said average current through said load is at least partially determinative of the exact frequency of oscillation of said power amplifier means.

Claim 23

A feedback control system as defined in claim 15, wherein: said load current sensing means produces a voltage proportional to the load current; and said controlled feedback means includes a voltage threshold device connected in series with an electrical gate between said load current sensing means and said summing point, said gate being enabled by said predetermined condition of a preselected particular parameter of said load, said oscillatory mode of said system being initiated when said voltage proportional to said load current exceeds the threshold voltage of said threshold device.

Claim 24

A feedback control system as defined in claim 19, wherein: said oscillatory mode of said system defines a pulse-width modulation mode for said power amplifier means.

Claim 25

A feedback control system as defined in claim 19, wherein: the sum of the phase lags of said load and said first and second phase lag electrical networks is such that the feedback signal due to the load current applied to said input of said power amplifier means through said controlled feedback is positive over a preselected range of frequencies to produce an oscillatory condition in said power amplifier means defining a pulse-width modulation mode for said system when said controlled feedback means is enabled.

Claim 26

A feedback control system as defined in claim 21, wherein: the frequency range of oscillations of said power amplifier means is sufficiently higher than the bandwidth characteristics of said feedback control system so that the current through said load is substantially averaged; and said average current through said load is at least partially determinative of the exact frequency of oscillation of said power amplifier means.

Claim 27

A feedback control system as defined in claim 22, wherein: said load is a linear actuator including an actuator coil and said one particular load parameter is the velocity of said coil.

Claim 28

A feedback control system as defined in claim 23, wherein: said controlled feedback means includes a second threshold device connected to said sensing means and said gate, said gate being enabled when a coil velocity signal from said sensing means exceeds the threshold level of said second threshold device.

Claim 29

A feedback control system as defined in claim 19, wherein: said load is a linear actuator including an actuator coil and said one particular load parameter is the velocity of said coil.

Claim 30

A feedback control system as defined in claim 25, wherein: said controlled feedback means includes a second threshold device connected to said sensing means and said gate, said gate being enabled when a coil velocity signal from said sensing means exceeds the threshold level of said second threshold device.