Balance control method of capacitor voltage on direct current side of cascaded multi-level rectifier
A technology of multi-level rectification and DC side capacitance, which is applied in the direction of converting irreversible AC power input to DC power output, and can solve the problems of inability to completely avoid switching loss and increase switching loss
Active Publication Date: 2018-01-05
STATE GRID JIANGSU ELECTRIC POWER CO LTD NANTONG POWER SUPPLY BRANCH +1
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Problems solved by technology
[0004] The balance effect of the sorting method is good, but when the level is switched, additional switching times will be introduced, which will increase the switching loss. Therefore, the literature also proposes an improved method that allows the DC voltage to fluctuate to a certain extent, which can reduce the increased switching loss. , but the DC ripple is introduced, and the additional switching loss cannot be completely avoided
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[0018] A cascaded multi-level rectifier DC side capacitor voltage balance control method adopts a discrete control method, and the control algorithm is only performed at the bottom and apex of the triangular wave, but not every apex and bottom point need to be calculated by the control algorithm;
[0019] When defining the bottom of the triangular wave, the output level of the module in the PWM state is H, and at the apex of the triangular wave, the output level of the module in the PWM state is L;
[0020] For CHB converters, through conventional power and current control and PD_PWM modulation, n states Uc1,..., Ucn to be allocated can be obtained;
[0021] Judging the current time according to the phase of the triangular wave carrier, decide which distribution method to adopt: if it is at the bottom of the triangular wave at time B, use "state distribution method 1", if it is at the top of the triangle wave at time T, use "state distribution method 2";
[0022] "State alloca...
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The invention discloses a balance control method of the capacitor voltage on the direct current side of a cascaded multi-level rectifier. In the method, a discrete control mode is adopted, a control algorithm is only conducted on the bottom and the top of a triangular wave, but not every bottom or top needs to be calculated through the control algorithm. The invention provides an improved rankingmethod and sets a switching timing sequence. According to the fundamental principle, any one level has to be switched into a PWM state first and then switched into another level when switched, the time for switching of the levels from high to low and the time for switching of the levels from low to high are stipulated, and it can be completely avoided that the number of the switching times is increased.
Description
technical field [0001] The invention relates to a cascaded multilevel rectifier DC side capacitor voltage balance control method. Background technique [0002] With the increasing application of power electronics technology in power systems, power electronic converters need to withstand higher and higher voltages. When the voltage value that the converter needs to withstand exceeds the withstand voltage value of a single power device, it is necessary to use the form of device series connection or circuit series connection. Among them, the cascaded multilevel converter (CHB) has the advantages of modular structure, easy expansion, no need for direct series connection of devices, and multi-level operation. It is obtained in power system devices such as static var compensation (STATCOM) and power electronic transformers. extensive research and applications. [0003] Since the input power of the modules is different in different states, the power balance among the modules can ...
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Inventor 吉宇季晨宇张炜
Owner STATE GRID JIANGSU ELECTRIC POWER CO LTD NANTONG POWER SUPPLY BRANCH