Current control system for inverter
First Claim
1. A current control system for an inverter having a plurality of series circuits formed by series-connecting electric valves each formed by connecting a semiconductor device and a diode in an inverted parallel relation to each other, each of said series circuits having both its ends connected respectively to a positive side and a negative side of a direct-current power source, wherein an inductive load is connected to the series connecting point of said electric valves, and current flowing through said inductive load is controlled in a pulse-width-modulation manner, said current control system comprising:
- current-command computing means for computing a q-axis current command in accordance with an operational command with respect to the load;
current detecting means for detecting an actual q-axis current flowing through the load;
q-axis-current error computing means for computing a q-axis current error which is a difference between said q-axis current command and said q-axis-current detecting value;
q-axis-current control computing means for performing pulse-width-modulation control computation of the q-axis current on the basis of said q-axis current error;
magnetic-flux phase-angle detecting means for detecting or computing a phase angle of a magnetic flux; and
control-phase potential computing means for determining a q-axis-current control phase and a reference potential phase on the basis of a computation result of said q-axis-current control computing means and a magnetic-flux rotational angle, to control a potential in each phase,wherein, in connection with the above, a direction, in which the phase angle is different by a predetermined reference angle from the magnetic flux occurring in the load, is defined as the q-axis, and a current component in the q-axis direction is defined as the q-axis current.
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Accused Products
Abstract
A current component, in which a phase angle is different by a predetermined reference angle from a magnetic flux occurring in an inductive load, is brought to a q-axis current. The q-axis current is computed on the basis of phase current. A phase angle of the magnetic flux is detected. A q-axis-current control phase and a reference potential phase are determined on the basis of the result of pulse-width-modulation computation and the phase angle. The q-axis-current control phase is controlled in a pulse-width-modulation manner. A potential of the remaining reference potential phase if fixed to a reference potential. Thus, interference among the phases is prevented to reduce current ripple.
105 Citations
23 Claims
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1. A current control system for an inverter having a plurality of series circuits formed by series-connecting electric valves each formed by connecting a semiconductor device and a diode in an inverted parallel relation to each other, each of said series circuits having both its ends connected respectively to a positive side and a negative side of a direct-current power source, wherein an inductive load is connected to the series connecting point of said electric valves, and current flowing through said inductive load is controlled in a pulse-width-modulation manner, said current control system comprising:
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current-command computing means for computing a q-axis current command in accordance with an operational command with respect to the load; current detecting means for detecting an actual q-axis current flowing through the load; q-axis-current error computing means for computing a q-axis current error which is a difference between said q-axis current command and said q-axis-current detecting value; q-axis-current control computing means for performing pulse-width-modulation control computation of the q-axis current on the basis of said q-axis current error; magnetic-flux phase-angle detecting means for detecting or computing a phase angle of a magnetic flux; and control-phase potential computing means for determining a q-axis-current control phase and a reference potential phase on the basis of a computation result of said q-axis-current control computing means and a magnetic-flux rotational angle, to control a potential in each phase, wherein, in connection with the above, a direction, in which the phase angle is different by a predetermined reference angle from the magnetic flux occurring in the load, is defined as the q-axis, and a current component in the q-axis direction is defined as the q-axis current. - View Dependent Claims (3, 5, 7, 10, 13, 15, 18, 20)
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2. A current control system for an inverter having a plurality of series circuits formed by series-connecting electric valves each formed by connecting a semiconductor device and a diode in an inverted parallel relation to each other, each of said series circuits having both its ends connected respectively to a positive side and a negative side of a direct-current power source, wherein an inductive load is connected to the series connecting point of said electric valves, and current flowing through said inductive load is controlled in a pulse-width-modulation manner, said current control system comprising:
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current-command computing means for computing a q-axis current command and a d-axis current command in accordance with an operational command with respect to the load; current detecting means for detecting an actual q-axis current and an actual d-axis current which flow through the load; q-axis-current error computing means for computing a q-axis current error which is a difference between said q-axis-current command and said q-axis-current detecting value; d-axis-current error computing means for computing a d-axis current error which is a difference between said d-axis-current command and said d-axis-current detecting value; q-axis-current control computing means for performing pulse-width-modulation control computation of the q-axis current on the basis of said q-axis current error; d-axis-current control computing means for performing pulse-width-modulation control computation of d-axis current on the basis of said d-axis current error; magnetic-flux phase-angle detecting means for detecting or computing a phase angle of a magnetic flux; and control-phase potential computing means for determining a q-axis-current control phase, a d-axis-current control phase and a reference potential phase on the basis of a computation result of said q-axis-current control computing means, a computation result of said d-axis-current control computing means and a magnetic-flux phase angle, to control a potential in each phase, wherein, in connection with the above, a direction, in which the phase angle is different by a predetermined reference angle from the magnetic flux occurring in the load, is defined as the q-axis, and a current component in the q-axis direction is defined as the q-axis current, and wherein a direction of the magnetic flux occurring in said load is defined as a d-axis, and a current component in the d-axis direction is defined as the d-axis current. - View Dependent Claims (4, 6, 8, 9, 11, 12, 14, 16, 17, 19, 21, 22)
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23. A current control system for an inverter having a plurality of series circuits formed by series connecting electric valves each formed by connecting a semiconductor device and a diode in an inverted parallel relation to each other, each of said series circuits having both its ends connected respectively to a positive side and a negative side of a direct-current power source, wherein an alternating-current motor is connected to the series connecting point of said electric valves, and current flowing through said alternating-current motor is controlled in a pulse-width-modulation manner, said current control system comprising:
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current-command computing means for computing a torque-current command; current detecting means for detecting a torque current; torque-current error computing means for computing a torque-current error between said torque-current command and said torque current; torque-current control computing means for computing, in a pulse-width-modulation manner, the torque current on the basis of said torque-current error; magnetic-flux rotational-angle detecting means for detecting a rotational angle of a magnetic flux; and control-phase potential computing means for determining the torque-current control phase and the reference potential phase on the basis of a result of the torque-current control computation and the magnetic-flux rotational angle, to control a potential in each phase.
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Specification