Electromagnetic contactor
AssigneeMitsubishi Electric Corporation
InventorsTomoyuki Kamiyama, Katsutoshi Ikarashi, Kazuki Takahashi
Life of this patent
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Abstract
A coil drive device energizes an operation coil to close an electromagnetic contactor. A rectifier outputs, to a power supply line, an input voltage obtained by full-wave rectification of an AC voltage supplied from a main power source. A controller controls on and off of a switching element connected to a power supply line in series with the operation coil. The controller controls a duty ratio that is an on period ratio of the switching element in each switching period in accordance with a value of a parameter calculated from a detected value of the input voltage, in at least a partial period after start of energization of the operation coil in response to a close command for the electromagnetic contactor.
Claims12
An electromagnetic contactor comprising:
- a first contact;
- a second contact;
- a mechanism to generate a biasing force for opening the first and second contacts;
- an operation coil to generate an electromagnetic force for bringing the first and second contacts into contact with each other against the biasing force;
- and
- a coil drive device to supply current for generating the electromagnetic force to the operation coil,
- the coil drive device including
- a rectifier to output, to a power supply line, an input voltage obtained by full-wave rectification of an AC voltage supplied from an AC power source,
- a switching element connected to the power supply line in series with the operation coil,
- a voltage detector to detect the input voltage, and
- a controller to control on and off of the switching element, wherein
- the controller controls on and off of the switching element so as to control a duty ratio that is a ratio of an on period of the switching element in a switching period shorter than one cycle of the AC voltage, and controls the duty ratio in accordance with a value of a first parameter indicating a magnitude of the input voltage that is calculated using a detected value of the voltage detector, in at least a partial period after start of energization of the operation coil in response to a close command for the electromagnetic contactor, and
- when a calculation value of the first parameter is larger than a predetermined reference value, the duty ratio is set to a value lower than when the calculation value is equal to or smaller than the reference value, wherein the reference value is set to a value of the first parameter corresponding to a nominal value of the AC voltage, and
- when the calculation value of the first parameter is larger than the reference value, the controller sets the duty ratio in accordance with a value obtained by dividing the reference value by the calculation value.
An electromagnetic contactor comprising:
- a first contact;
- a second contact;
- a mechanism to generate a biasing force for opening the first and second contacts;
- an operation coil to generate an electromagnetic force for bringing the first and second contacts into contact with each other against the biasing force;
- and
- a coil drive device to supply current for generating the electromagnetic force to the operation coil,
- the coil drive device including
- a rectifier to output, to a power supply line, an input voltage obtained by full-wave rectification of an AC voltage supplied from an AC power source,
- a switching element connected to the power supply line in series with the operation coil,
- a voltage detector to detect the input voltage, and
- a controller to control on and off of the switching element, wherein
- the controller controls on and off of the switching element so as to control a duty ratio that is a ratio of an on period of the switching element in a switching period shorter than one cycle of the AC voltage, and controls the duty ratio in accordance with a value of a first parameter indicating a magnitude of the input voltage that is calculated using a detected value of the voltage detector, in at least a partial period after start of energization of the operation coil in response to a close command for the electromagnetic contactor, and
- when a calculation value of the first parameter is larger than a predetermined reference value, the duty ratio is set to a value lower than when the calculation value is equal to or smaller than the reference value, wherein
- the controller determines the duty ratio of the switching element by multiplying an adjustment coefficient that reflects individual differences of the operation coil.
Dependencies are inferred from the claim text.