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交流、直流、线性直流或高频:我们应使用哪种点焊电源?

交流、直流、线性直流或高频:我们应使用哪种点焊电源?

首先,我们来谈谈闭环焊机和开环焊机之间的区别。简单地说,闭环焊机使用传感器来测量焊接过程中的电流和电压,这样您就可以随时调整零件和工艺的变化; 开环焊工不 - 你只是得到你得到的。

 

CLOSED LOOP TECHNOLOGIES:  线性直流和高频逆变器

在线性直流电源,电容器组被充电和焊接能量通过晶体管的银行释放。线性直流电源提供超稳定输出,上升时间非常快。大多数直流电源可以采用恒定电流,恒定电压或恒定功率进行编程。时间控制可以以小至0.01毫秒的增量进行编程。由于直流电源提供最佳的低能量控制,因此它是焊接细线和薄箔的最佳选择。

高频逆变器技术利用脉冲宽度调制电路来控制焊接能量。三相输入电流被全波整流为直流,然后切换以在焊接变压器的初级产生交流电流。经过整流后产生的二次电流呈DC形式,具有强制的低电平AC纹波。与线性直流直流焊机一样,高频逆变器可以编程为恒定电流,电压或功率操作。时间控制可以以1毫秒或0.01毫秒的增量进行编程。高频逆变器具有非常高的重复率,因此它们经常用于自动化应用。

 

开环技术:电容放电(CD)和直接能量(AC):

电容放电(CD)电源在焊接之前将能量存储在电容器组中。能量通过脉冲变压器释放到焊头。由此产生的高峰值电流和非常快的上升时间对于焊接非常导电的部件非常有用。电容器组上的电荷水平通常以瓦特秒或%能量编程。通过改变变压器抽头设置来实现时间控制,这改变了脉冲持续时间或脉冲宽度。遗憾的是,由于电容器放电电源是开环的(无反馈),因此次级电路的变化,例如松散的电缆或腐蚀的连接可能导致向部件的能量输送不一致。

直接能量(AC)电源在焊接时直接从电力线获取能量。通过改变焊接变压器上的抽头设置来实现粗调电流控制,这改变了输出的电压。通过控制施加到焊接变压器初级的AC功率的百分比来实现焊接电流的精细调节。焊接时间以线路周期控制(1个周期= 16.67毫秒@ 60赫兹),最小值通常为半个周期。线路电压波动会影响开环交流电源提供的焊接电流。因此,输入线必须很好地调节。交流电源是具有高能量输出的通用焊机(不适用于关键的精细焊接应用)。焊接时间越长适用于电阻钎焊应用。

First of all, let's talk about the difference between closed loop and open loop welders.  Simply put, closed loop welders use sensors to measure the current and voltage during the weld so you can adjust for part and process variation as you go; open loop welders don't - you just get what you get.

 

CLOSED LOOP TECHNOLOGIES:  Linear DC and HF Inverter

In Linear DC power supplies, a capacitor bank is charged up and the welding energy is released through a bank of transistors.  Linear DC power supplies deliver an ultra stable output with a very fast rise time.  Most DC power supplies can be programmed in constant current, constant voltage, or constant power.  Time control can be programmed in increments as small as 0.01 milliseconds.  Because DC power supplies offer the best low energy control, it is the best choice for welding fine wires and thin foils.

High frequency inverter technology utilizes pulse width modulation circuitry to control the weld energy.  3-phase input current is full wave rectified to DC, which is then switched to produce an AC current at the primary of the welding transformer.  The resulting secondary current, when rectified, is in the form of DC with an imposed, low-level AC ripple.  Like Linear DC welders, High Frequency Inverters can be programmed for constant current, voltage, or power operation.  Time control can be programmed in 1 millisecond or 0.01 millisecond increments.  High Frequency Inverters have very high repetition rates, so they are frequently used for automated applications.

 

OPEN LOOP TECHNOLOGIES: Capacitor Discharge (CD) and Direct Energy (AC):

Capacitor Discharge (CD) power supplies store energy in a capacitor bank prior to the weld.  The energy is discharged through a pulse transformer to the weld head.  The resulting high peak current and very fast rise time is useful for welding very conductive parts.  The level of charge on the capacitor bank is usually programmed in watt-seconds or % energy.  Time control is achieved by changing the transformer tap settings, which changes the pulse duration, or pulse width.  Unfortunately, since a capacitor discharge power supply is open loop (no feedback), changes in the secondary circuit, such as loose cables or corroded connections can result in inconsistent energy delivery to the parts.

Direct Energy (AC) power supplies take energy directly from the power line as the weld is being made.  Coarse current control is achieved by changing the tap settings on the welding transformer, which changes the voltage of the output.  Fine adjustment of weld current is achieved by controlling the amount, in percent, of the AC power that is applied to the primary of the welding transformer.  The weld time is controlled in line cycles (1 cycle = 16.67 milliseconds @ 60 Hz), the minimum usually being one half cycle.  Line voltage fluctuations can affect the weld current delivered by open loop AC power supplies.  For this reason, the input line must be well regulated.  AC power supplies are general purpose welders with high energy output (not suitable for critical, fine welding applications).  The longer welding times are useful for resistance brazing applications.


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