Modulation method of a five-phase and above converter
A modulation method and converter technology, which are applied in the direction of converting AC power input to DC power output, output power conversion devices, electrical components, etc. Control difficulties and other problems, to achieve the effect of easy implementation, reduced complexity, and simple control methods
Active Publication Date: 2019-05-31
中科海奥(黄山)储能科技有限公司
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Problems solved by technology
With the increase of the number of converter phases, the control of the midpoint potential of the converter is more difficult, the calculation of zero sequence voltage in the carrier modulation method based on zero sequence voltage injection, and the complexity of the redundant vector allocation rules in the space vector modulation method Huge improvements
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[0032] In this embodiment, a modulation method for a five-phase or more converter is to detect output phase voltages of a three-level converter and determine the magnitude relationship of the phase voltages. Calculate the action time of each phase 0, 1, and 2 level of the converter that meets the midpoint potential balance condition, and then obtain the double modulation wave of the multi-phase converter. Specifically, the steps are as follows:
[0033] Step 1. Use a voltage sensor to collect the upper capacitor voltage u on the DC side of the converter C1 and the lower capacitor voltage u C2 , and the output phase voltage of the converter, and after arranging the output phase voltages in descending order, record it as the first phase voltage u 1 , the second phase voltage u 2 ,..., kth phase voltage u k ,..., Nth phase voltage u N , k=1,2,...,N;
[0034] In specific implementation, such as figure 1 As shown, each phase bridge arm of the converter is composed of four swi...
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The invention discloses a modulation method of a converter with five or more phases. The modulation method comprises the following steps of 1, collecting the upper and lower capacitor voltages and theoutput-phase voltages of a converter, and arranging the output-phase voltages in sequence from large to small; 2, acquiring a linear voltage equation of the multi-phase converter; 3, obtaining the neutral point potential balance condition of the converter; 4, calculating the action time of the levels 0, 1 and 2 in each phase; 5, according to the calculated duty ratio, obtaining the double-modulation wave of the converter; 6, summing up independent PWM sequences obtained through comparing the double-modulation wave of the converter with the single-carrier wave of the converter to obtain the switching sequence of the converter. In this way, the modulation of the multi-phase converter is realized. According to the invention, the converter can normally work in the condition that the number ofphases is large. The operation reliability of the converter is improved, and therefore the optimal control of the converter is achieved.
Description
technical field [0001] The present invention relates to a modulation method of a three-level converter, and more specifically relates to a modulation method of a converter when the number of phases of the converter is five or more. Background technique [0002] Compared with the three-phase motor, the multi-phase AC motor not only increases the torque ripple frequency and reduces the torque ripple amplitude, but also improves the output power of the entire variable current speed regulation system due to the increase of the total output current. The capacity requirements of converter power devices are also reduced. In addition, increasing the number of phases is also conducive to improving the speed regulation characteristics and fault tolerance performance in the low-speed area. When one or more phases of the multi-phases fail, the motor can still start and run with reduced power through proper control. In order to reduce the current, large-capacity multi-phase AC motors us...
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IPC IPC(8): H02M7/487
Inventor 姜卫东李劲松王金平王培侠翟飞
Owner 中科海奥(黄山)储能科技有限公司