Variable speed controller for an AC motor
AssigneeFuji Electric Co., Ltd.
InventorsHirokazu Tajima, Hidetoshi Umida, Hiroshi Tetsutani
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Abstract
To provide a trans-vector controller for an alternating current ("AC") motor that facilitates operating the secondary resistance of the AC motor without experimentally rotating the AC motor. In a preferred embodiment, the variable speed control circuit, including a secondary resistance value generating device, changes the direct current ("DC") exciting current and operates the secondary resistance of an induction motor by superimposing an AC signal with small amplitude outputted from a AC signal generator onto a reference current value immediately before the start of the induction motor in the state of DC excitation.
Claims11
A variable speed controller of an alternating current ("AC") motor, including detectors for detecting an actual voltage and an actual current of said AC motor fed from an electric power converter, coordinate transformers for resolving said actual voltage to an M-axis voltage component and a T-axis voltage component perpendicular to said M-axis voltage component and for resolving said actual current to an M-axis current component and a T-axis current component perpendicular to said M-axis current component, said variable speed controller executing trans-vector control of said AC motor based on said M-axis components and said T-axis components, said variable speed controller further comprising:
- (a) an AC signal generator, said AC signal generator generating an AC signal with small amplitude during a predetermined period immediately before the rotation of said motor;
- (b) a reference value generator, said reference value generator generating a reference M-axis current value, a reference speed value and a reference secondary magnetic flux value;
- (c) a first adder, said first adder adding said AC signal and said reference M-axis current value;
- (d) an M-axis current regulator, said M-axis current regulator executing regulating operation of the difference between the output of said first adder and said M-axis current component;
- (e) a speed regulator, said speed regulator executing regulating operation of the difference between said reference speed value and an actual speed value of said AC motor;
- (f) a T-axis current regulator, said T-axis current regulator executing regulating operation of the difference between the output of said speed regulator and said T-axis current component;
- (g) a coordinate transformer, said coordinate transformer executing coordinate transformation based on the output of said T-axis current regulator, the output of said M-axis current regulator and a reference phase angle value, whereby to generate a gate signal of said electric power converter;
- (h) an induced voltage operating device, said induced voltage operating device operating an induced M-axis voltage value of said AC motor based on said M-axis current component and said M-axis voltage component;
- (i) a slip frequency operating device, said slip frequency operating device operating a slip frequency of said AC motor based on said reference secondary magnetic flux value, the output of said speed regulator and a secondary resistance value;
- (j) a second adder, said second adder adding said slip frequency and said actual speed value;
- (k) an integrator, said integrator integrating the output of said second adder, said integrator outputting the result of said integrating as said reference phase angle value;
- (l) a secondary resistance value generating device, arranged to adaptively compute said secondary resistance value without experimentally rotating said AC motor, and to store and output said secondary resistance value;
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- (m) said variable speed controller executing trans-vector control of said AC motor based on said stored secondary resistance value when said AC motor is rotating.
A variable speed controller of an alternating current ("AC") motor, including detectors for detecting an actual voltage and an actual current of said AC motor fed from an electric power converter, coordinate transformers for resolving said actual voltage to an M-axis voltage component and a T-axis voltage component perpendicular to said M-axis voltage component and for resolving said actual current to an M-axis current component and a T-axis current component perpendicular to said M-axis current component, said variable speed controller executing trans-vector control of said AC motor based on said M-axis components and said T-axis components, said variable speed controller further comprising:
- (a) an AC signal generator, said AC signal generator generating an AC signal with small amplitude during a predetermined period immediately before the rotation said motor;
- (b) a reference value generator, said reference value generator generating a reference M-axis current value, a reference T-axis voltage value and a reference phase angle;
- (c) an adder, said adder adding said AC signal and said reference M-axis current value;
- (d) a current regulator, said current regulator executing regulating operation of the difference between the output of said adder and said M-axis current component;
- (e) a coordinate transformer, said coordinate transformer executing coordinate transformation based on the output of said current regulator, said reference T-axis voltage value and said reference phase angle, whereby to obtain a gate signal of said electric power converter;
- (f) an induced voltage operating device, said induced voltage operating device operating an induced M-axis voltage value of said AC motor based on said M-axis current component and said M-axis voltage component;
- (g) a secondary resistance value generating device, arranged to adaptively compute a secondary resistance value without experimentally rotating said AC motor, and to store and output said secondary resistance value;
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- (h) said variable speed controller executing trans-vector control of said AC motor based on said stored secondary resistance value when said AC motor is rotating.
Dependencies are inferred from the claim text.