Balance control method of three-phase SCR (semiconductor control rectifier) power regulator

Abstract

The invention relates to a three-phase SCR (semiconductor control rectifier) power regulator, and in particular relates to a balance control method of the three-phase SCR (semiconductor control rectifier) power regulator. According to the balance control method disclosed by the invention, a control angle of each phase of the three-phase SCR power regulator is alpha within a range of 0-180 DEG, the control angle alpha of each phase is respectively reduced from beta by the SCP power regulator, and beta is within a range of 0-180 DEG, so that the output voltage of each phase of the three-phase SCR power regulator is changed, and a purpose of balancing voltage / current / power of a load is realized. The balance control method disclosed by the invention is suitable for regulation of all three-phase SCR power regulators with unbalance loads, and the control angle alpha of each phase of the three-phase SCR power regulator is respectively regulated so that the voltage balance or current balance or power balance is realized.

Description

technical field [0001] The invention relates to a three-phase SCR power regulator, in particular to a balance control method for the three-phase SCR power regulator. Background technique [0002] SCR power regulator is also called thyristor voltage regulator, power regulator or power controller. SCR power regulators are divided into single-phase SCR power regulators, two-phase SCR power regulators and three-phase SCR power regulators from the phase of control. There are two trigger control methods of the existing SCR power regulator: phase-shift trigger mode and zero-cross trigger mode. The phase-shift trigger mode is as attached figure 1 As shown, the output voltage is controlled by controlling the α angle; the zero-crossing trigger method is as attached figure 2 As shown, when the control angle α = 0 degrees, it is fully turned on, and when the control angle α = 180 degrees, it is fully turned off, and the output is controlled by controlling the duty ratio of opening an...

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Problems solved by technology

[0003] When the three-phase SCR power regulator is running with load, since the three-phase load cannot be exactly the same, there must be an unbalanced phenomenon of resistivity or inductance. The unbalance is generally between 0% and 20%, and some The unbalanced degree of three-phase load even exceeds 20%. Due to the existence of this phenomenon, it will inevitably lead to the unbalanced load three-phase voltage / current / power

[0004] In some applications, three-phase voltage balance is required, in some applications, three-phase current balance is required, and in some applications, three-phase power balance is required; and the balance degree of voltage / current / power affects the production process and products to a large extent. quality, and even cause the system not to work properly

In the face of unbalanced three-phase voltage / three-phase current / three-phase power caused by unbalanced load, the existing three-phase SCR power regulator is used for adjustment. Since the control angle α of the three phases is equal, the mutual difference of 120 is always maintained. degrees, as attached Figure 4 As shown, it is impossible to adjust the control angle of each phase independently. Measures such as changing the phase sequence of the input power supply, replacing the load, and replacing the transformer are often used to perform hardware random matching on the unbalanced phenomenon. The improvement effect is uncertain and the scrap rate is high. , it is difficult to achieve satisfactory results

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