High-dynamic-response pulse width modulation method at low switching frequency

A low switching frequency, pulse width modulation technology, applied in the direction of AC motor control, control system, electrical components, etc., can solve problems such as difficult to achieve control requirements, difficult to ensure system control performance, increase program processing complexity, etc.

Active Publication Date: 2014-05-28
ZHUZHOU CSR TIMES ELECTRIC CO LTD
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Problems solved by technology

[0024] (1) As the modulation ratio continues to increase, the reference voltage vector will be located in the over-modulation area, which requires special processing to achieve the purpose of modulation, which increases the complexity of program processing to a certain extent, and is difficult to c

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  • High-dynamic-response pulse width modulation method at low switching frequency
  • High-dynamic-response pulse width modulation method at low switching frequency
  • High-dynamic-response pulse width modulation method at low switching frequency

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Embodiment Construction

[0112] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0113] Such as Figure 12 As shown, a high dynamic response pulse width modulation method under a low switching frequency of the present invention, the steps are:

[0114] (1) In the offline state, with the goal of eliminating specific sub-current harmonics, the optimization algorithm is used to calculate the modulation ratio as a variable, and calculate the corresponding switching angle for each frequency division number;

[0115] (2) The principle of judging and choosing is put forward for the calculated switching angle: if the obtained stator flux linkage shape is a regular 6-gon, 18-gon or 30-gon, that is, when the number of sides differs by 12, it will be adopted, otherwise it will be discarded ;

[0116] (3) Store the switching angle corresponding to the modulation ratio in a fixed position in the hardware in order or perform ...

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Abstract

The invention discloses a high-dynamic-response pulse width modulation method at a low switching frequency. The method comprises the steps that (1) in the offline state, an optimization algorithm is adopted for calculation with the modulation ratio as a variable for the purpose of eliminating specific secondary current harmonics, so that switching angles corresponding to all frequency division numbers are calculated; (2) judgment and rejection principles are put forward for the calculated switching angles, wherein if the shape of an obtained stator flux link is a regular hexagon or a regular octadecagon or a regular shape with 30 edges, namely the difference of the numbers of the edges is 12, the switching angles are adopted, and the switching angles are abandoned otherwise; (3) the switching angles corresponding to the modulation ratio are sequentially stored at fixed positions in hardware, or curve fitting is conducted on the switching angles, so that the corresponding relation between the modulation ratio and the switching angles is obtained; (4) in the actual operation process of a system, table look-up or calculation is conducted according to the modulation ratio and the frequency division numbers, so that all the switching angles are obtained. The high-dynamic-response pulse width modulation method at the low switching frequency has the advantages that the specific subharmonics can be effectively eliminated, so that system noise and torque pulsation are lowered, and the dynamic responsiveness of the system can be greatly improved at the same time.

Description

technical field [0001] The invention mainly relates to the field of AC drive systems, in particular to a pulse width modulation method with high dynamic response at low switching frequency suitable for AC drive systems. Background technique [0002] The AC drive system refers to a new type of drive system that takes the AC motor as the control object and adjusts the output torque and speed of the motor. Compared with the DC drive system, the AC drive system has good traction performance, high power factor, small size, light weight and reliable operation. The AC drive system is gradually replacing the DC drive system and is widely used in various fields of industrial production, national life and national defense. [0003] The AC transmission system is generally composed of a control system, a main circuit and a control object, among which the main circuit includes a DC bus, a DC support capacitor, and a converter composed of power switching semiconductor devices; the contro...

Claims

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Application Information

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IPC IPC(8): H02P27/08
Inventor 冯江华尚敬梅文庆刘勇刘良杰甘韦韦周志宇江平胡仙贾岩
Owner ZHUZHOU CSR TIMES ELECTRIC CO LTD
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