High speed RMS control apparatus for resistance welders and high speed RMS control method thereof

Claim 2

A control apparatus for controlling a resistance welder which comprises a welding transformer, a primary winding of which is connected to an AC power supply and a secondary winding of which is connected to a welding gun, and a switching element inserted between said AC power supply and the primary welding of said welding transformer and fired at a predetermined firing phase, comprising: storage means for calculating and storing a square sum SK wherein a sinusoidal wave VK=K0 sinθK having a predetermined peak value and corresponding to an AC component of said AC power supply is sampled at predetermined phase intervals θK within a predetermined phase range, square values VK 2 of the sinusoidal wave are calculated at each of the phase intervals θK, and square sum SK=V1 2 +V2 2 +V3 2 . . . +VK 2 is calculated; and Vx calculating means for reading out a value, Sn, of the square sum at the firing phase and a value, Sm, of the square sum at a phase upon completion of energization of said switching element from said storage means, and calculating a normalized effective value Vx obtained by normalizing an effective value of the AC power supply voltage on the basis of the readout square sums Sn and Sm; control means using the normalized effective value Vx for controlling the application of a voltage to the primary winding of the welding transformer.

Claim 3

An apparatus according to claim 1, wherein said switching element includes anti-parallel connected thyristors.

Claim 4

An apparatus according to claim 1, wherein said resistance welder comprises a single-phase full-wave resistance welder.

Claim 5

An apparatus according to claim 1, wherein said storage means includes a data table storing the square sum SK calculated in advance.

Claim 6

An apparatus according to claim 1, further comprising: effective current detecting means for detecting an effective current Irms flowing through said welding transformer; and means for current-controlling said switching element using the effective current Irms as a control feedback signal.

Claim 7

An apparatus according to claim 1, wherein the normalized effective Vx is defined by Vx=K1√S180-Sn+Sm where K1 and S180 are constants.

Claim 8

A control apparatus used for controlling a resistance welder which comprises a welding transformer, a primary winding of which is connected to an AC power supply and a secondary winding of which is connected to a welding gun, and a switching element inserted between said AC power supply and the primary winding of said welding transformer and fired at a predetermined firing phase, comprising: storage means for calculating and storing a square sum SK wherein a sinusoidal wave VK=K0 sinθK having a predetermined peak value and corresponding to an AC component of said AC power supply is sampled at predetermined phase intervals θK within a predetermined phase range, square values VK 2 of the sinusoidal wave are calculated at each of the phase intervals θK and square sum SK=V1 2 +V2 2 +V3 2 +. . . +VK 2 is calculated; Vx calculating means for reading out a value, Sn, of the square sum at the firing phase and a value, Sm, of the square sum at a phase upon completion of energization of said switching element from said storage means and calculating a normalized effective value Vx obtained by normalizing an effective value of the AC power supply voltage on the basis of read out square sums Sn and Sm; voltage detecting means for detecting a voltage of said AC power supply; Vrms calculating means for calculating an effective value Vrms from the AC power supply voltage detected by said voltage detecting means; Vt calculating means for calculating an effective voltage Vt applied to the primary winding of said welding transformer using the effective value Vrms and the normalized effective value Vs; control means for controlling the application of an effective voltage Vt to the primary of the welding transformer; and means for voltage-controlling said switching element using the effective voltage Vt as a control feedback signal.

Claim 9

A control apparatus used for controlling a resistance welder which comprises a welding transformer, a primary winding of which is connected to an AC power supply and a secondary winding of which is connected to a welding gun, and a switching element inserted between said AC power supply and the primary winding of said welding transformer and fired at a predetermined firing phase, comprising: storage means for calculating and storing a square sum SK wherein a sinusoidal wave VK=K0 sinθK having a predetermined peak value and corresponding to an AC component of said AC power supply is sampled at predetermined phase intervals θK within a predetermined phase range, square values VK 2 of the sinusoidal wave are calculated at each of the phase intervals θK and square sum SK=V1 2 +V2 2 +V3 2 +. . . +VK 2 is calculated; Vx calculating means for reading out a value, Sn, of the square sum at the firing phase and a value, Sm, of the square sum at a phase upon completion of energization of said switching element from said storage means and calculating a normalized effective value Vx obtained by normalizing an effective value of the AC power supply voltage on the basis of read out square sums Sn and Sm; voltage detecting means for detecting a voltage of said AC power supply; Vrms calculating means for calculating an effective value Vrms from the AC power supply voltage detected by said voltage detecting means; Vt calculating means for calculating an effective voltage Vt applied to the primary winding of said welding transformer using the effective value Vrms and the normalized effective value Vs; control means for controlling the application of an effective voltage Vt to the primary of the welding transformer; and means for voltage-controlling said switching element using the effective voltage Vt as a control feedback signal.

Claim 10

A control apparatus used for controlling a resistance welder which comprises a welding transformer, a primary winding of which is connected to an AC power supply and a secondary winding of which is connected to a welding gun, and a switching element inserted between said AC power supply and the primary winding of said welding transformer and fired at a predetermined firing phase, comprising: storage means for calculating and storing a square sum SK wherein a sinusoidal wave VK=K0 sinθK having a predetermined peak value and corresponding to an AC component of said AC power supply is sampled at predetermined phase intervals θK within a predetermined phase range, square value VK 2 of the sinusoidal wave are calculated at each of the phase intervals θK and square sum SK=V1 2 30 V2 2 +V3 2 +. . . +VK 2 is calculated; Vx calculating means for reading out a value, Sn, or the square sum at the firing phase and a value, Sm, of the square sum at a phase upon completion of energization of said switching element from said storage means, and calculating a normalized effective value Vx obtained by normalizing an effective value of the AC power supply voltage on the basis of read out square sums Sn and Sm; control means using the normalized effective value Vx for controlling the application of a voltage to the primary winding of the welding transformer; P calculating means for calculating a use rate P of said welding transformer on the basis of a ratio of a present value to a maximum value of the normalized effective value Vx; and means for displaying the calculated use rate P.

Claim 11

A control apparatus used for controlling a resistance welder which comprises a welding transformer, a primary winding of which is connected to an AC power supply and a secondary winding of which is connected to a welding gun, and a switching element inserted between said AC power supply and the primary winding of said welding transformer and fired at a predetermined firing phase, comprising: storage means for calculating and storing a square sum SK wherein a sinusoidal wave VK=K0 sinθK having a predetermined peak value and corresponding to an AC component of said AC power supply is sampled at predetermined phase intervals θK within a predetermined phase range, square value VK 2 of the sinusoidal wave are calculated at each of the phase intervals θK and square sum SK=V1 2 30 V2 2 +V3 2 +. . . +VK 2 is calculated; Vx calculating means for reading out a value, Sn, or the square sum at the firing phase and a value, Sm, of the square sum at a phase upon completion of energization of said switching element from said storage means, and calculating a normalized effective value Vx obtained by normalizing an effective value of the AC power supply voltage on the basis of read out square sums Sn and Sm; control means using the normalized effective value Vx for controlling the application of a voltage to the primary winding of the welding transformer; P calculating means for calculating a use rate P of said welding transformer on the basis of a ratio of a present value to a maximum value of the normalized effective value Vx; and means for displaying the calculated use rate P.

Claim 12

A control apparatus for controlling a resistance welder which comprises a welding transformer, a primary winding of which is connected to an AC power supply and a secondary winding of which is connected to a welding gun, and a switching element inserted between said AC power supply and the primary winding of said welding transformer and fired at a predetermined firing phase, comprising: storage means for calculating and storing a square sum SK wherein a sinusoidal waveform VK sinθK corresponding to an AC component of said AC power supply is sampled at predetermined phase intervals θK, and square values VK 2 of the AC components are calculated at each of the predetermined phase intervals θK square sum SK=V1 2 +V2 2 V+V3 2 +. . . +VK 2 wave VK corresponding to the phases is calculated; Vx calculating means for reading out a value, Sn, of the square sum at the firing phase and a value, Sm, of the square sum at a phase upon completion of energization of said switching element from said storage means and calculating a normalized effective value Vx obtained by normalizing an effective value of the AC power supply voltage on the basis of the readout square sums Sn and Sm; control means using the normalized effective value Vx for controlling the application of a voltage to the primary of the welding transformer; P calculating means for calculating a use rate P of said welding transformer on the basis of a ratio of a present value to a maximum value of the normalized effective value Vx; and means for displaying the calculated use rate P.

Claim 13

A control apparatus for controlling a resistance welder which comprises a welding transformer, a primary winding of which is connected to an AC power supply and a secondary winding of which is connected to a welding gun, and a switching element inserted between said AC power supply and the primary winding of said welding transformer and fired at a predetermined firing phase, comprising: storage means for calculating and storing a square sum SK wherein a sinusoidal waveform VK sinθK corresponding to an AC component of said AC power supply is sampled at predetermined phase intervals θK, and square values VK 2 of the AC components are calculated at each of the predetermined phase intervals θK square sum SK=V1 2 +V2 2 V+V3 2 +. . . +VK 2 wave VK corresponding to the phases is calculated; Vx calculating means for reading out a value, Sn, of the square sum at the firing phase and a value, Sm, of the square sum at a phase upon completion of energization of said switching element from said storage means and calculating a normalized effective value Vx obtained by normalizing an effective value of the AC power supply voltage on the basis of the readout square sums Sn and Sm; control means using the normalized effective value Vx for controlling the application of a voltage to the primary of the welding transformer; P calculating means for calculating a use rate P of said welding transformer on the basis of a ratio of a present value to a maximum value of the normalized effective value Vx; and means for displaying the calculated use rate P.

Claim 14

An apparatus according to claim 9, further comprising: Vrms calculating means for calculating an effective value Vrms of an AC voltage of said AC power supply; Vt calculating means for calculating an effective voltage Vt applied to the secondary winding of said welding transformer using the effective value Vrms and the normalized effective value Vx; and means for voltage-controlling said switching element using the effective voltage Vt as a control feedback signal.

Claim 17

A method according to claim 11, further comprising the steps of: detecting a voltage of said AC power supply; calculating an effective value Vrms using the detected AC power supply voltage; calculating the effective voltage Vt applied to the primary winding of said welding transformer using the effective value Vrms and the normalized effective value Vx; and voltage-controlled said switching element using the effective voltage Vt as a control feedback signal.

Claim 18

A method according to claim 11, further comprising the steps of: detecting an effective current Irms flowing through said welding transformer; and current-controlling said switching element using the effective current Irms as a control feedback signal.

Claim 25

A control apparatus for controlling a single-phase full-wave resistance welder in which anti-parallel connected thyristors are connected in series with a primary winding of a welding transformer and which controls a firing phase θn of said thyristors to adjust a welding current, comprising: storage means for calculating and storing a square sum SK wherein a sinusoidal value VK=32 K0 sinθK having a given peak value is sampled at predetermined phase intervals θK within a predetermined phase range, and the square sum SK=V1 2 +V2 2 +V3 2 +. . . +VK 2 of the sinusoidal value VK with respect to each phase interval θK is calculated in advance; first calculating means for reading out square sums Sn and Sm at the firing phase θn and energization end phase θm from said storage means and calculating a normalized effective value Vx of an effective voltage applied to said welding transformer; and control means using the normalized effective value Vx for controlling the application of a voltage to the primary of the welding transformer.

Claim 26

A control apparatus for controlling a single-phase full-wave resistance welder in which anti-parallel connected thyristors are connected in series with a primary winding of a welding transformer and which controls a firing phase θn of said thyristors to adjust a welding current, comprising: storage means for calculating and storing a square sum SK wherein a sinusoidal value VK=32 K0 sinθK having a given peak value is sampled at predetermined phase intervals θK within a predetermined phase range, and the square sum SK=V1 2 +V2 2 +V3 2 +. . . +VK 2 of the sinusoidal value VK with respect to each phase interval θK is calculated in advance; first calculating means for reading out square sums Sn and Sm at the firing phase θn and energization end phase θm from said storage means and calculating a normalized effective value Vx of an effective voltage applied to said welding transformer; and control means using the normalized effective value Vx for controlling the application of a voltage to the primary of the welding transformer.

Claim 27

An apparatus according to claim 17, further comprising: voltage detecting means for detecting a voltage of an AC power supply; Vrms calculating means for calculating an effective voltage Vrms of said AC power supply from the detected voltage; second calculating means for calculating an effective voltage Vt applied to said welding transformer on the basis of the effective voltage Vrms and the normalized effective value Vx; and voltage control means for performing voltage control using the effective voltage Vt as a feedback signal.

Claim 28

An apparatus according to claim 17, further comprising: effective current detecting means for detecting an effective current Irms of said welding transformer; and current control means for performing current control using the effective current Irms as a feedback signal.

Claim 29

An apparatus according to claim 17, wherein the normalized effective Vx is defined by Vx=K1√S180-Sn+Sm where K1 and S180 are constants.

Claim 30

A control apparatus for controlling a single-phase full-wave resistance welder in which anti-parallel connected thyristors are connected in series with a primary winding of a welding transformer and which controls a firing phase θn of said thyristors to adjust a welding current, comprising: storage means for calculating and storing a square sum SK wherein a sinusoidal value VK =K0 sinθK having a given peak value is sampled at predetermined phase intervals θK within a predetermined phase range, and the square sum SK=V1 2 +V2 2 +V3 2 +. . . VK 2 of the sinusoidal value VK with respect to each phase interval θK is calculated in advance; first calculating means for reading out square sums Sn and Sm at the firing phase θn and energization end phase θm from said storage means and calculating a normalized effective value Vx of an effective voltage applied to said welding transformer; control means using the normalized effective value Vx for controlling the application of a voltage to the primary of the welding transformer; third calculating means for calculating a use rate P of said welding transformer; and display means for displaying the use rate P.

Claim 31

A control apparatus for controlling a single-phase full-wave resistance welder in which anti-parallel connected thyristors are connected in series with a primary winding of a welding transformer and which controls a firing phase θn of said thyristors to adjust a welding current, comprising: storage means for calculating and storing a square sum SK wherein a sinusoidal value VK =K0 sinθK having a given peak value is sampled at predetermined phase intervals θK within a predetermined phase range, and the square sum SK=V1 2 +V2 2 +V3 2 +. . . VK 2 of the sinusoidal value VK with respect to each phase interval θK is calculated in advance; first calculating means for reading out square sums Sn and Sm at the firing phase θn and energization end phase θm from said storage means and calculating a normalized effective value Vx of an effective voltage applied to said welding transformer; control means using the normalized effective value Vx for controlling the application of a voltage to the primary of the welding transformer; third calculating means for calculating a use rate P of said welding transformer; and display means for displaying the use rate P.

Claim 32

A control apparatus for controlling a single-phase full-wave resistance welder in which anti-parallel connected thyristors are connected in series with a primary winding of a welding transformer and which controls a firing phase θn of said thyristors to adjust a welding current, comprising: storage means for calculating and storing a square sum SK wherein a sinusoidal value VK=K0 sinθK having a given peak value is sampled at predetermined phase intervals θK within a predetermined phase range, and the square sum SK=V1 2 +V2 2 +V3 2 +. . . VK 2 of the sinusoidal value VK with respect to each phase interval θK is calculated in advance; first calculating means for reading out square sums Sn and Sm at the firing phase θn and energization end phase θm from said storage means and calculating a normalized effective value Vx of an effective voltage applied to said welding transformer; control means using the normalized effective value Vx for controlling the application of a voltage to the primary of the welding transformer; third calculating means for calculating a use rate P of said welding transformer; display means for displaying the use rate P; effective current detecting means for detecting an effective current Irms of said welding transformer; and current control means for performing current control using the effective current Irms as a feedback signal.

Claim 33

A control apparatus for controlling a single-phase full-wave resistance welder in which anti-parallel connected thyristors are connected in series with a primary winding of a welding transformer and which controls a firing phase θn of said thyristors to adjust a welding current, comprising: storage means for calculating and storing a square sum SK wherein a sinusoidal value VK=K0 sinθK having a given peak value is sampled at predetermined phase intervals θK within a predetermined phase range, and the square sum SK=V1 2 +V2 2 +V3 2 +. . . VK 2 of the sinusoidal value VK with respect to each phase interval θK is calculated in advance; first calculating means for reading out square sums Sn and Sm at the firing phase θn and energization end phase θm from said storage means and calculating a normalized effective value Vx of an effective voltage applied to said welding transformer; control means using the normalized effective value Vx for controlling the application of a voltage to the primary of the welding transformer; third calculating means for calculating a use rate P of said welding transformer; display means for displaying the use rate P; effective current detecting means for detecting an effective current Irms of said welding transformer; and current control means for performing current control using the effective current Irms as a feedback signal.