Cascaded multilevel converter based on zero-sequence voltage minimum space vector modulation control
A technology of space vector modulation and cascaded multi-level, which is applied in the direction of output power conversion device, AC power input to DC power output, electrical components, etc. It is easy to implement by computer and avoid calculation of trigonometric functions and irrational numbers
Active Publication Date: 2021-04-23
NANCHANG INST OF TECH
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Problems solved by technology
Redundant switch status leads to problems such as heavy computational workload and complex switching path selection. When the number of cascaded units increases, the amount of calculation increases exponentially, and the difficulty of SVPWM implementation increases greatly.
[0005] Based on the above-mentioned difficulties in the implementation of traditional SVPWM technology, it is necessary to study a new cascaded multilevel converter space vector modulation method
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[0076] The following is an example of a 4-level 9-level converter (that is, n=4, the number of levels a, b, c∈[±4, ±3, ±2, ±1, 0] of the three-phase output voltage), the H bridge Sub-module input DC voltage U dc =100V, the modulation coefficient of the phase voltage reference signal m=0.95, the angular frequency of the reference signal ω=100π, the sampling period T s =0.2ms, the present invention is described in further detail in conjunction with accompanying drawing and specific embodiment:
[0077] When sampling at t=5.2ms, the modulation method includes the following steps:
[0078] Step 1: For the three phase voltage reference signals u ra , u rb , u rc Sampled: u ra =-0.276, u rb =3.93, u rc =-3.655, according to the formula (2) to calculate α r =3.379, β r =4.206, namely the reference vector to alpha r and beta r Round to α 0 = 3, β 0 =4.
[0079] distance reference vector The four nearest basis vectors are base vector form a unit square.
[0080...
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The invention discloses a cascaded multilevel converter based on zero-sequence voltage minimum space vector modulation control, the cascaded multilevel converter is a three-phase n-stage multilevel converter, each phase is formed by connecting n voltage type single-phase full-bridge inverter sub-modules in series, and the single-phase full-bridge inverter sub-modules are H bridges. Each H bridge is composed of four IGBTs and an anti-parallel diode. The cascade multilevel converter control system comprises a control module, and the control module samples three phase voltage reference signals and generates 12*n paths of PWM pulses to control the operation of the cascade multilevel converter; the modulation method executed in the control module is a method based on a zero sequence voltage minimum space vector modulation. According to the scheme, the switching state with the minimum zero-sequence voltage in all the switching states corresponding to the basic vector can be directly obtained, an algorithm can be achieved only through comparison and simple arithmetic operation, complex trigonometric function and irrational number calculation is avoided, and the method is easy to achieve through a computer.
Description
technical field [0001] The invention belongs to the field of inverter modulation and relates to a cascaded multilevel converter based on zero-sequence voltage minimum space vector modulation control. Background technique [0002] Cascaded multi-level converter topology is the earliest multi-level converter circuit. After more than 20 years of development, especially the demand for medium-high voltage and high-power converters in industrial production has increased. Great attention has been paid to the device topology. The cascaded converter uses low-voltage power devices to achieve high-voltage and large-capacity output, which overcomes the problem that the voltage level and capacity of the converter are limited by the withstand voltage and capacity of a single power switching device, and the number of cascaded units can be increased according to application requirements to increase the output voltage. The number of levels, thereby increasing the voltage level and capacity ...
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IPC IPC(8): H02M7/483
CPCH02M7/483
Inventor 曾瑄曾文军涂振宇王翠王沄禾李常学段万政欧阳俊铭
Owner NANCHANG INST OF TECH