Electromagnetic contactor

Patent metadata

Field	Value
Publication number	US-11735387-B2
Application number	US-202017632308-A
Country	US
Kind code	B2
Filing date	Oct 5, 2020
Priority date	Oct 17, 2019
Publication date	Aug 22, 2023
Grant date	Aug 22, 2023

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.

First claim

The invention claimed is:

1. 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.

2. 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.

3. The electromagnetic contactor according to claim 2 , 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.

4. The electromagnetic contactor according to claim 3 , wherein
when the calculation value is equal to or smaller than the reference value, the controller sets the duty ratio to 1.

5. The electromagnetic contactor according to claim 1 , wherein
when the calculation value is equal to or smaller than the reference value, the controller sets the duty ratio to 1.

6. The electromagnetic contactor according to claim 1 , wherein
the controller determines the duty ratio of the switching element by multiplying an adjustment coefficient that reflects individual differences of the operation coil.

7. The electromagnetic contactor according to claim 1 , further comprising a current detector to detect coil current flowing through the operation coil, wherein
the adjustment coefficient is calculated using a value of a second parameter indicating a magnitude of the coil current that is calculated using a detected value of the current detector during energization of the operation coil, a value of the first parameter calculated using the detected value of the voltage detector during the energization, and reference characteristic values of the first and second parameters obtained in advance during energization of the operation coil having characteristics serving as a reference.

8. The electromagnetic contactor according to claim 1 , wherein the controller sets the duty ratio to 0 at start of supply of the AC voltage to the rectifier to await energization of the operation coil, performs calculation of the first parameter using the detected value of the voltage detector, and after acquiring a calculation value of the first parameter, starts energization of the operation coil with control of the duty ratio in accordance with the calculation value.

9. The electromagnetic contactor according to claim 1 , wherein the controller sets the duty ratio larger than 0 from start of supply of the AC voltage to the rectifier to start energization of the operation coil, performs calculation of the first parameter using the detected value of the voltage detector, and after acquiring a calculation value of the first parameter, controls the duty ratio in accordance with the calculation value.

10. The electromagnetic contactor according to claim 1 , wherein
when a predetermined determination time has elapsed since start of energization of the operation coil, the controller sets the duty ratio lower than before elapse of the determination time, and
the determination time is set to be longer than a required time from the start of energization to when the electromagnetic contactor is brought into a closed state by contact between the first and second contacts.

11. The electromagnetic contactor according to claim 1 , wherein
the first parameter is an effective value, and
the controller extracts a maximum value of the detected value of the input voltage by the voltage detector in a period equal to or longer than a half cycle of the AC voltage and calculates the effective value by multiplying the maximum value by a predetermined coefficient.

12. The electromagnetic contactor according to claim 1 , wherein the controller changes the switching period of the switching element with elapse of time, in control of the duty ratio.

Assignees

• Mitsubishi Electric Corp

Inventors

• Kamiyama Tomoyuki
• Ikarashi Katsutoshi
• Takahashi Kazuki

Classifications

• H01H47/36 Primary

  Relay coil or coils forming part of a bridge circuit · CPC title

• H01H47/002

  Monitoring or fail-safe circuits · CPC title

• H01H47/325 Primary

  by switching regulator · CPC title

• H01H47/04

  for holding armature in attracted position, e.g. when initial energising circuit is interrupted; for maintaining armature in attracted position, e.g. with reduced energising current {(with switching regulator H01H47/325)} · CPC title