The reliability index of a product is an extremely important part of its quality attributes. Taking the three-phase electric voltage stabilizer as an example, the higher the reliability of the product, the lower the maintenance cost, which can minimize the user's expenses and ensure the normal operation of the user's equipment. At the same time, only products with high reliability can have real competitiveness in the market. The regulated power supply of power semiconductor devices has many advantages such as high efficiency, good control performance, small size, light weight, and reliable use.

1. Mechanical pressure regulating type. The carbon brush is driven by the servo motor to move on the sliding surface of the winding of the autotransformer, changing the ratio of the output voltage (Vo) to the input voltage (Vi), so as to realize the adjustment and stability of the output voltage of the regulated power supply. It is characterized by simple structure, low cost, and small output waveform distortion. However, due to the sliding of the carbon brush, electric sparks are likely to be generated at the contacts, causing the brush to be damaged or even burnt to fail, and the voltage adjustment speed is slow.

Second, change the tap type. The autotransformer is made into multiple fixed taps, and the relay or thyristor (solid-state relay) is used as the switch control to automatically change the tap position, so as to realize the stability of the output voltage. This type of voltage regulator has the advantages of simple circuit, wide single-phase voltage regulation range (130V-280V), high efficiency (≥95%), and low price. The disadvantage is that the precision of the voltage regulation is low (± 8 ~ 10%) and the working life is short. It is suitable for households to supply power to air conditioners.

Three, oil induction type. A device that stabilizes the output AC voltage by changing the phase difference between the secondary voltage of the transformer and the primary voltage. It is similar in structure to a wire-wound asynchronous motor, and in principle it is similar to an induction voltage regulator. It has a wide range of voltage regulation, good output voltage waveform, and the power can reach hundreds of kilowatts. However, since the rotor is often in a locked-rotor state, the power consumption is large and the efficiency is low. In addition, due to the large amount of copper and iron used, there is less production.

Four, electronic thyristor type. By controlling the on-off of the bidirectional thyristor, the taps of the autotransformer are switched, thereby changing the magnitude and polarity of the compensation voltage of the compensation transformer, and achieving the purpose of stabilizing the output voltage. Due to the use of autotransformer taps for step-by-step voltage regulation, it not only reduces the on-off voltage of the bidirectional thyristor (from 220V to below 200V), but also suppresses the surge current generated when shifting gears (the autotransformer itself is a high-power The reactor), thus greatly improving the reliability of the bidirectional thyristor.