Control system for suppressing torque ripple in synchronous motor

Claim 2

A control system for suppressing torque ripple of a synchronous motor, comprising: (a) the synchronous motor having multi-phase armature windings and a field winding; (b) a frequency converter for supplying AC current of variable frequencies to said armature windings; (c) a position detector for producing a sinusoidal waveform signal in dependence on the rotational position of said synchronous motor and having a substantially constant amplitude independent of the rotational speed of said motor; (d) compensation means for compensating the armature reaction of said synchronous motor; (e) current detector means for detecting armature current of said synchronous motor; (f) torque computation circuit for arithmetically determining actual torque value from said sinusoidal waveform position signal and said armature current; and (g) control means for controlling output current of said frequency converter in response to deviation of said actual torque value from a command torque value for suppressing torque ripple of said synchronous motor even at low motor speeds.

Claim 3

A control system for suppressing torque ripple of a synchronous motor, comprising: (a) the synchronous motor having multi-phase armature windings and a field winding; (b) a frequency converter for supplying AC current of variable frequencies to said armature windings; (c) a position detector for producing a sinusoidal waveform signal in dependence on the rotational position of said synchronous motor; (d) compensation means for compensating the armature reaction of said synchronous motor; (e) current detector means for detecting armature current of said synchronous motor; (f) torque computation circuit for arithmetically determining actual torque value from said sinusoidal waveform position signal and said armature current; (g) a speed control circuit for comparing an actual speed value with a speed command signal thereby to produce a torque command value; (h) a torque control circuit for comparing said torque command value with said actual torque value thereby to produce a torque difference signal; (i) a current control circuit for controlling the output current of said frequency converter in dependence on a current command signal obtained by modulating said sinusoidal waveform position signal through said torque difference signal; and (j) an amplitude limiter circuit for limiting amplitude of said current command signal.

Claim 4

A control system for suppressing torque ripple of a synchronous motor, comprising: (a) the synchronous motor having multi-phase armature windings and a field winding; (b) a frequency converter for supplying AC current of variable frequencies to said armature windings; (c) a position detector for producing a sinusoidal waveform signal in dependence on the rotational position of said synchronous motor; (d) compensation means for compensating the armature reaction of said synchronous motor; (e) current detector means for detecting armature current of said synchronous motor; (f) torque computation circuit for arithmetically determining actual torque value from said sinusoidal waveform position signal and said armature current; (g) a speed control circuit for comparing an actual speed value with a speed command signal thereby to produce a torque command value; (h) a torque control circuit for comparing said torque command value with said actual torque value thereby to produce a torque difference signal; (i) a current control circuit for controlling the output current of said frequency converter in dependence on a current command signal obtained by modulating said sinusoidal waveform position signal through said torque difference signal; and (j) an amplitude limiter circuit for limiting amplitude of said current command signal.

Claim 5

A control system for suppressing torque ripple of a synchronous motor, comprising: (a) the synchronous motor having multi-phase armature windings and a field winding; (b) a frequency converter for supplying AC current of variable frequencies to said armature windings; (c) a position detector for producing a sinusoidal waveform signal in dependence on the rotational position of said synchronous motor; (d) compensation means for compensating the armature reaction of said synchronous motor; (e) current detector means for detecting armature current of said synchronous motor; (f) torque computation circuit for arithmetically determining actual torque value from said sinusoidal waveform position signal and said armature current; (g) a speed control circuit for comparing an actual speed value with a speed command signal thereby to produce a torque command value; (h) a torque control circuit for comparing said torque command value with said actual torque value thereby to produce a torque difference signal; (i) a current control circuit for controlling the output current of said frequency converter in dependence on a current command signal obtained by modulating said sinusoidal waveform position signal through said torque difference signal; (j) an amplitude limiter circuit for limiting amplitude of said current command signal; and (k) a limit value command circuit for varying the limit value of said amplitude limiter circuit in dependence on rotation speeds of said synchronous motor.

Claim 6

A control system for suppressing torque ripple of a synchronous motor, comprising: (a) the synchronous motor having multi-phase armature windings and a field winding; (b) a frequency converter for supplying AC current of variable frequencies to said armature windings; (c) a position detector for producing a sinusoidal waveform signal in dependence on the rotational position of said synchronous motor; (d) compensation means for compensating the armature reaction of said synchronous motor; (e) current detector means for detecting armature current of said synchronous motor; (f) torque computation circuit for arithmetically determining actual torque value from said sinusoidal waveform position signal and said armature current; (g) a speed control circuit for comparing an actual speed value with a speed command signal thereby to produce a torque command value; (h) a torque control circuit for comparing said torque command value with said actual torque value thereby to produce a torque difference signal; (i) a current control circuit for controlling the output current of said frequency converter in dependence on a current command signal obtained by modulating said sinusoidal waveform position signal through said torque difference signal; (j) an amplitude limiter circuit for limiting amplitude of said current command signal; and (k) a limit value command circuit for varying the limit value of said amplitude limiter circuit in dependence on rotation speeds of said synchronous motor.

Claim 7

A control system for suppressing torque ripple of a synchronous motor, comprising: (a) the synchronous motor having multi-phase armature windings and a field winding; (b) a frequency converter for supplying AC current of variable frequencies to said armature windings; (c) a position detector for producing a sinusoidal waveform signal in dependence on the rotational position of said synchronous motor and having a substantially constant amplitude independent of the speed of said motor; (d) a voltage computation circuit for arithmetically determining terminal voltage of said synchronous motor at a preset rotation speed on the basis of said sinusoidal position signal; (e) current detector means for detecting armature current of said synchronous motor; (f) a torque computation circuit for arithmetically determining an actual torque value on the basis of said terminal voltage from said voltage computation circuit and said armature current; and (g) control means for controlling output current of said frequency converter in response to deviation of said actual torque value from a command torque value for suppressing torque ripple of said synchronous motor even at low motor speeds.

Claim 8

A control system for suppressing torque ripple of a synchronous motor, comprising: (a) the synchronous motor having multi-phase armature windings and a field winding; (b) a frequency converter for supplying AC current of variable frequencies to said armature windings; (c) a position detector for producing a sinusoidal waveform signal in dependence on the rotational position of said synchronous motor and having a substantially constant amplitude independent of the speed of said motor; (d) a voltage computation circuit for arithmetically determining terminal voltage of said synchronous motor at a preset rotation speed on the basis of said sinusoidal position signal; (e) current detector means for detecting armature current of said synchronous motor; (f) a torque computation circuit for arithmetically determining an actual torque value on the basis of said terminal voltage from said voltage computation circuit and said armature current; and (g) control means for controlling output current of said frequency converter in response to deviation of said actual torque value from a command torque value for suppressing torque ripple of said synchronous motor even at low motor speeds.

Claim 9

A control system for suppressing torque ripple of a synchronous motor, comprising: (a) the synchronous motor having multi-phase armature windings and a field winding; (b) a frequency converter for supplying AC current of variable frequencies to said armature windings; (c) a position detector for producing a sinusoidal waveform signal in dependence on the rotational position of said synchronous motor; (d) a voltage computation circuit for arithmetically determining terminal voltage of said synchronous motor at a preset rotation speed on the basis of said sinusoidal position signal; (e) current detector means for detecting armature current of said synchronous motor; (f) a torque computation circuit for arithmetically determining an actual torque value on the basis of said terminal voltage from said voltage computation circuit and said armature current; (g) control means for controlling output current of said frequency converter in response to deviation of said actual torque value from a command torque value; and (h) a field current control circuit for controlling the field current of said synchronous motor.

Claim 10

A control system for suppressing torque ripple of a synchronous motor, comprising: (a) the synchronous motor having multi-phase armature windings and a field winding; (b) a frequency converter for supplying AC current of variable frequencies to said armature windings; (c) a position detector for producing a sinusoidal waveform signal in dependence on the rotational position of said synchronous motor; (d) a voltage computation circuit for arithmetically determining terminal voltage of said synchronous motor at a preset rotation speed on the basis of said sinusoidal position signal; (e) current detector means for detecting armature current of said synchronous motor; (f) a torque computation circuit for arithmetically determining an actual torque value on the basis of said terminal voltage from said voltage computation circuit and said armature current; (g) control means for controlling output current of said frequency converter in response to deviation of said actual torque value from a command torque value; and (h) a field current control circuit for controlling the field current of said synchronous motor.

Claim 11

A control system for suppressing torque ripple of a synchronous motor, comprising: (a) the synchronous motor having multi-phase armature windings and a field winding; (b) a controllable rectifier device for converting AC current into DC current; (c) a power inverter for converting the DC output of said controllable rectifier device into AC current to be supplied to said armature windings; (d) a position detector for producing a sinusoidal waveform signal in dependence on the rotational position of said synchronous motor and having a substantially constant amplitude independent of the speed of said motor; (e) a voltage computation circuit for arithmetically determining terminal voltage of said synchronous motor at a preset rotation speed on the basis of said sinusoidal position signal; (f) current detector means for detecting armature current of said synchronous motor; (g) a torque computation circuit for arithmetically determining an actual torque value on the basis of said terminal voltage from said voltage computation circuit and said armature current; and (h) control means for controlling output current of said frequency converter in response to deviation of said actual torque value from a command torque value for suppressing torque ripple of said synchronous motor even at low motor speeds.

Claim 12

A control system for suppressing torque ripple of a synchronous motor, comprising: (a) the synchronous motor having multi-phase armature windings and a field winding; (b) a controllable rectifier device for converting AC current into DC current; (c) a power inverter for converting the DC output of said controllable rectifier device into AC current to be supplied to said armature windings; (d) a position detector for producing a sinusoidal waveform signal in dependence on the rotational position of said synchronous motor and having a substantially constant amplitude independent of the speed of said motor; (e) a voltage computation circuit for arithmetically determining terminal voltage of said synchronous motor at a preset rotation speed on the basis of said sinusoidal position signal; (f) current detector means for detecting armature current of said synchronous motor; (g) a torque computation circuit for arithmetically determining an actual torque value on the basis of said terminal voltage from said voltage computation circuit and said armature current; and (h) control means for controlling output current of said frequency converter in response to deviation of said actual torque value from a command torque value for suppressing torque ripple of said synchronous motor even at low motor speeds.