A cascade system, static pressure equalization method, and control device

Abstract

The invention discloses a cascade system, a static voltage equalization method, and a control device, including a power bridge arm, and the power bridge arm includes a plurality of power sub-modules, each power sub-module is provided with a charging terminal and an input terminal, each The input end of the power sub-module is connected in parallel with a bypass switch assembly, the charging end of each power sub-module is connected in parallel with a first charging assembly and each power sub-module is provided with a voltage for detecting the charging condition of the first charging assembly Detection module, the input ends of multiple power sub-modules are connected in series in sequence, the charging end of the power sub-module can supply power for external objects, and the bypass switch assembly can be closed or disconnected according to the detection signal of the voltage detection module. This design The cost can be reduced, the reliability can be improved, and the static voltage equalization effect of the power sub-module can be significantly improved, so that the system can operate stably with power supply.

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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