Rectifier Bridge

China rectifier bridge supplier

Is the bridge rectifier a diode?
The rectifier bridge is a kind of rectifier. It can be said that the rectifier diode is the simplest rectifier.
The rectifier bridge generally has a sufficiently large inductive load, so there is no current discontinuity in the rectifier bridge. Generally, when the rectifier bridge is used, a smoothing reactor is often connected to its load end, so its load can be regarded as a constant current source. Multiple groups of three-phase rectifier bridges are connected to each other, so that the harmonics generated by the rectifier bridge circuits cancel each other out. According to the type of rectifier transformer, it can be divided into traditional multi-pulse transformer rectifier and self-coupling multi-pulse transformer rectifier. The traditional multi-pulse transformer rectifier uses an isolation transformer to isolate the input voltage and output voltage, but the equivalent capacity of the rectifier transformer is large and bulky.

The principle of rectifier bridge

As shown in Figure 1 on the right, the rectifier bridge is controlled by the control angle of the controller. When the control angle is 0°～90°, the rectifier bridge is in the rectification state, and the average value of the output voltage is positive; When the control angle is 90°～180°-γ (γ is the arc switching angle), the rectifier bridge is in the inverter state, and the average value of the output voltage is negative.

Multi-pulse rectification technology

Multi-pulse rectification means that in a three-phase power system, the output DC voltage has more than 6 waves in one cycle, usually with 12, 18, 24 pulses. A multi-pulse rectifier usually consists of two parts: a phase-shifting rectifier transformer and a rectifier bridge. The input three-phase voltage is phase-shifted through the transformer, and several sets of three-phase voltage are generated and output to the rectifier bridge. Multiple groups of three-phase rectifier bridges are connected to each other, so that the harmonics generated by the rectifier bridge circuits cancel each other out. The multi-pulse rectification technology can not only reduce the harmonics of the AC input current, but also reduce the amplitude of the harmonics in the DC output voltage and increase the ripple frequency.

Multi-pulse rectification technology can be divided into 12, 18, 24 and other pulse rectifiers according to the wave head of the rectification. The larger the number of pulses, the better the input current and output voltage characteristics of the rectifier, but the more complex the rectifier system is. According to the type of rectifier transformer, it can be divided into traditional multi-pulse transformer rectifier and self-coupling multi-pulse transformer rectifier. The traditional multi-pulse transformer rectifier uses an isolation transformer to isolate the input voltage and output voltage, but the equivalent capacity of the rectifier transformer is large and the volume is huge. Autotransformer rectifiers are different from traditional multi-pulse transformers. Autotransformer rectification does not use isolation technology, but puts the windings on the same core column, which not only saves the volume, but also reduces the equivalent capacity of the transformer accordingly. According to whether the energy transmitted by each group of rectifier bridges is equal, multi-pulse rectification can be divided into symmetrical and asymmetrical multi-pulse rectification. Symmetrical multi-pulse rectification means that the output voltages of the rectifier bridges are equal, and the rectifier bridges are in a parallel relationship, and they do not interfere with each other; The asymmetric structure means that the rectifier bridges are in a master-slave relationship when the rectifier bridges are working. The main rectifier bridge transmits most of the power, and the auxiliary rectifier bridge transmits part of the power. The main rectifier bridge and the auxiliary rectifier bridge will affect each other. But the symmetrical structure increases the balance reactor.