Cascading system, static voltage-sharing method and control device

Abstract

The invention discloses a cascade system, a static voltage-sharing method and a control device. The system comprises a power bridge arm, the power bridge arm comprises a plurality of power sub-modules. Each power sub-module is provided with a charging end and an input end; the input end of each power sub-module is connected with a bypass switch assembly in parallel. The charging end of each powersub-module is connected with a first charging assembly in parallel, and each power sub-module is provided with a voltage detection module used for detecting the charging condition of the first charging assembly. The input ends of the plurality of power sub-modules are sequentially connected in series; the charging end of the power sub-module can supply power to an external object, the bypass switch assembly can be switched on or switched off according to a detection signal of the voltage detection module, the cost can be reduced, the reliability can be improved, the static voltage-sharing effect of the power sub-module can be remarkably improved, and the system can stably supply power and operate.

Description

technical field [0001] The invention relates to the field of power electronics, in particular to a cascade system, a static voltage equalization method, and a control device. Background technique [0002] The traditional cascade system is composed of multiple power bridge arms, and the power bridge arm is composed of the input terminals of multiple power sub-modules in series, and then the two ends of the power bridge arm are respectively connected to the positive and negative poles of DC power, each The charging terminals of each power sub-module will be connected in parallel with the first charging component (such as a charging capacitor). When the power sub-module is put into operation, the charging terminal of the power sub-module will charge the first charging component. Objects (such as the control board of the system, etc.) supply power. [0003] However, after the cascade system is powered on and started, due to the lack of reasonable control over the charging of ea...

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Problems solved by technology

[0003] However, after the cascade system is powered on and started, due to the lack of reasonable control over the charging of each power sub-module, it may cause uneven distribution of electric energy on each of the first charging components, which may eventually lead to a large loss of the first charging The power loss of the components is reduced to below the minimum power required by the external objects to obtain power, resulting in the loss of power of the external objects, the system fails and shuts down, or the first charging component with a small loss is kept charging, and the first charging component is damaged. Happening

[0004] In order to solve the above problems, the traditional voltage equalization method is to connect energy-discharging modules in parallel on the first charging components of each power sub-module, and the energy-discharging modules can be formed by connecting multiple energy-discharging components (such as resistors) in parallel, and each The parallel branches of each energy-dissipating component are provided with switching components. When the electric energy reserve of the first charging component of a certain power sub-module is relatively high, the switching components of more parallel-connected branches in the energy-dissipating module are closed at this time. Make more energy-dissipating components put into use, consume the electric energy on the first charging assembly, and for the situation that the electric energy reserve of the first charging assembly is low, then relatively reduce the closing of the switching components of the parallel branch in the energy-discharging module, thereby Cut off the number of energy-dissipating components to reduce the loss of the first charging component. However, this method consumes a lot of power for the entire system. Although it can stabilize the power of each first charging component within a certain range to a certain extent, it still cannot achieve long-term use, there is still a risk of power failure

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