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选择桥式起重机变频器的三大技巧

1.变频器容量与整流装置相数关系

The 1 converter capacity and rectifier phase relationship

变频器装置投入6kV电网必须符合国家有关谐波抑制的规定。这和电网容量和装置的额定功率有关。短路容量在1000MVA以内,1000kW装置12相(变压器副边双绕组)即可,如果24相功率就可达2000kW,12相基本上消除了幅值较大的5次和7次谐波。整流相数超过36相后,谐波电流幅值降低不显著,而制造成本过高。如果电网短路容量2000MVA,则装置容许容量更大。

The frequency converter with input 6kV power system must be consistent with the provisions related to inhibition of harmonic state. This and the power capacity and the device rated power. Short circuit capacity within 1000MVA, 1000kW device 12 (secondary side of the transformer can be double winding), if the 24 phase power is up to 2000kW, 12 phase basically eliminated the 5 and 7 harmonics in bigger amplitude. Rectifier phase number more than 36 phase, harmonic current amplitude reduced significantly, and the manufacturing cost is too high. If the short circuit capacity of the power grid 2000MVA, the device allows greater capacity.

2.选择过高电压等级的弊端

2 select high voltage defects

选择过高的电压等级造成投资过高,回收期长。电压等级的提高,电机的绝缘必须提高,使电机价格增加。电压等级的提高,使变频器中电力半导体器件的串联数量加大,成本上升。可见,对于200~2000kW的电机系统采用6kV、10kV电压等级是极不经济、很不合理的。

Selection of voltage level is too high due to the high investment, long payback period. The increase of voltage grade, the insulation must improve the motor, the motor price increase. The increase of voltage grade, the power semiconductor devices in inverter series number increase, rising costs. Visible, for 200 ~ 2000kW motor system by 6kV, 10kV voltage grade is not economic, not very reasonable.

3.把最高电压降到3kV以下可节约大量投资

3 the highest voltage below 3kV can save a lot of investment

从电力电子器件特性及安全系数考虑电压等级的必要性,受电力电子器件电压及电机允许的dv/dt限制,6kV变频器必须采用多电平或多器件串联,造成线路复杂,价格昂贵,可靠性差。对于6kV变频器若是用1700VIGBT,以美国罗宾康的PERFECTHARMONY系列6kV高压变频器为例,每相由5个额定电压为690V的功率单元串联,三相共60只器件。若是用3300V器件,也需3串共30只器件,数量巨大。另一方面装置电流小,器件的电流能力得不到充分利用,以560kW为例,6kV电机电流仅60A左右,而1700V的IGBT电流已达2400A,3300V器件电流达1600A,有大器件不能用,偏要用大量小器件串联,极不合理。即使电机功率达2000kW,电流也只有140A左右,仍很小。

Considering the necessity of voltage level from the characteristics of electronic devices and safety coefficient of power, the power electronic device voltage and motor allows the dv/dt limit, 6kV converter must use the multi level or device series, cause line complex, expensive, poor reliability. For the 6kV inverter for 1700VIGBT, to American Luo Binkang PERFECTHARMONY series 6kV high voltage frequency converter as an example, each phase consists of 5 rated power unit 690V series, a total of 60 devices of three-phase. If using 3300V devices, also need 3 series a total of 30 devices, a huge number of. On the other hand device with small current, device current capacity is not fully utilized, taking 560kW as an example, 6kV motor current is only about 60A, while the IGBT 1700V current has reached 2400A, 3300V device current up to 1600A, a large device can not be used, must use a large number of small devices in series, unreasonable. Even if the motor power is 2000kW, the current is only about 140A, is still very small.

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