System for controlling a motor
First Claim
1. A system for controlling the speed of an alternating current elevator in which a direct current power from a direct current power source is converted into an alternating current power having a variable voltage and frequency by means of an inverter and the alternating power is supplied to an induction motor so that a cage is operated by controlling the motor in response to a speed command value, said system comprising an energy saving operation command unit which commands the energy saving operation;
- a low speed command generating circuit which generates a low speed command value lower than said speed command value; and
a frequency decreasing circuit which decreases the output frequency of the inverter in response to said low speed command value.
1 Assignment
0 Petitions
Accused Products
Abstract
An alternating current having a variable voltage and frequency which is converted by an inverter is supplied to an induction motor for driving an elevator so that a speed command value is decreased and the output frequency of the inverter is decreased at the energy saved operation. Thus, energy saved operation may be accomplished without adversing the efficiency even if the speed of the cage is decreased. Since the output voltage of the convertor is increased simultaneously with this, the power factor is improved so that saving in energy is furthermore enhanced.
-
Citations
19 Claims
-
1. A system for controlling the speed of an alternating current elevator in which a direct current power from a direct current power source is converted into an alternating current power having a variable voltage and frequency by means of an inverter and the alternating power is supplied to an induction motor so that a cage is operated by controlling the motor in response to a speed command value, said system comprising an energy saving operation command unit which commands the energy saving operation;
-
a low speed command generating circuit which generates a low speed command value lower than said speed command value; and a frequency decreasing circuit which decreases the output frequency of the inverter in response to said low speed command value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A system for controlling the speed of an alternating current elevator in which an alternating current power from a commercial alternating current power line is converted into a direct current power having a variable voltage by means of a convertor and the direct current power is converted into an alternating current power having a variable voltage and frequency by an inverter and the alternating current power is supplied to an induction motor and the motor is controlled in response to the speed command value to operate a cage, said system comprising;
-
an energy saving operation command unit which commands are energy saving operation; a low speed command generating circuit which generates a low speed command value lower than said speed command value when said energy saving operation command unit is operated; a voltage control circuit which increases the output voltage of said convertor above that before the operation of said command unit is operated; and a frequency decreasing circuit which decreases the output frequency of said inverter in response to said low speed command value. - View Dependent Claims (12, 13, 14, 15, 19)
-
- 16. The system for controlling the speed of the alternating current elevator as claimed in claim 16 in which said first and second circuits are provided with a command input line, said first circuit being adapted to directly output the input from the common input line, said second circuit being adapted to amplify the input from said common input line and outputs the amplified input.
Specification