System and method for automatic current limit control
First Claim
Patent Images
1. A motor controller system comprising:
- solid state switches for connection between an AC line and motor terminals for controlling application of AC power to the motor;
a sensor for sensing AC line voltage; and
a control circuit for controlling operation of the solid state switches, the control circuit ramping switch current during a start mode and selectively holding switch current during the start mode if sensed voltage drops below a threshold amount.
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Abstract
A motor controller system comprises solid state switches for connection between an AC line and motor terminals for controlling application of AC power to the motor. A sensor senses AC line voltage. A control circuit controls operation of the solid state switches. The control circuit ramps switch current during a start mode and selectively holds switch current during the start mode if sensed voltage drops below a threshold amount.
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Citations
21 Claims
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1. A motor controller system comprising:
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solid state switches for connection between an AC line and motor terminals for controlling application of AC power to the motor; a sensor for sensing AC line voltage; and a control circuit for controlling operation of the solid state switches, the control circuit ramping switch current during a start mode and selectively holding switch current during the start mode if sensed voltage drops below a threshold amount. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A motor starter system comprising:
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solid state switches for connection between an AC line and motor terminals for controlling application of AC power to the motor; a voltage sensor for sensing AC line voltage; current sensors for sensing switch current; and a control circuit operatively connected to the voltage sensor and the current sensors for controlling operation of the solid state switches during a start mode, the control circuit ramping switch current in a preselect range during the start mode and selectively holding switch current during the start mode if sensed voltage drops below a threshold amount. - View Dependent Claims (8, 9, 10, 11)
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12. A motor starter system comprising:
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solid state switch means for connection between an AC line and motor terminals for controlling application of AC power to the motor; voltage sensing means for sensing AC line voltage; current sensing means for sensing switch current; and start control means operatively connected to the voltage sensing means and the current sensing means for controlling operation of the solid state switch means during a start mode, the start control means ramping current through the switch means during the start mode and selectively holding switch means current during the start mode if sensed voltage drops below a threshold. - View Dependent Claims (13, 14, 15, 16)
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17. A method of limiting current during motor starting comprising:
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providing solid state switches for connection between an AC line and motor terminals for controlling application of AC power to the motor; sensing AC line voltage; sensing switch current; ramping current through the solid state switches during motor starting; and selectively holding switch current constant during motor starting if sensed voltage drops below a threshold. - View Dependent Claims (18, 19, 20)
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21. An elevator starter comprising:
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solid state switches for connection between an AC line and motor terminals for controlling application of AC power to the elevator; a voltage sensor for sensing AC line voltage; current sensors for sensing switch current; and a control circuit operatively connected to the voltage sensor and the current sensors for controlling operation of the solid state switches during a start mode, the control circuit ramping switch current in a preselect range during the start mode and selectively holding switch current during the start mode if sensed voltage drops below a threshold amount.
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Specification