Current ripple real-time prediction model-based three-level voltage source variable switching frequency control method

Abstract

The invention discloses a current ripple real-time prediction model-based three-level voltage source variable switching frequency control method. According to the control method, a current ripple real-time prediction module and a switching cycle updating module are established; and with a current ripple peak value adopted as a control object, the switching cycle of an inverter is updated in real time through using a current ripple real-time prediction model. With the three-level voltage source variable switching frequency control method adopted, the switching frequency of the inverter changes in real time, and therefore, compared with a traditional constant switching frequency PWM control algorithm, the control method of the invention can significantly decrease average switching frequency and greatly reduce the switching loss of the inverter; and since the switching frequency change range of the inverter is wide, spectrum distribution is broader, and a harmonic current peak value can be effectively reduced, and conducted EMI (electro-magnetic interference) can be effectively improved.

Description

technical field [0001] The invention belongs to the field of voltage source variable switching frequency, and more specifically relates to a three-level voltage source variable switching frequency control method based on a real-time prediction model of current ripple. Background technique [0002] Pulse Width Modulation (PWM) technology is the main modulation strategy for current power electronic converters to realize power conversion and control. PWM realizes the output of reference analog quantities through digital pulses. It follows the principle of volt-second balance in a single switching cycle and has a strong high-frequency characteristic. However, the power electronic converter is not an ideal power conversion device. While realizing power conversion, it faces the following problems: the power electronic converter has switching process and loss. In the high-frequency PWM mode, how to reduce the switching process and loss is a problem. Key issues; the power electroni...

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Problems solved by technology

However, the power electronic converter is not an ideal power conversion device. While realizing power conversion, it faces the following problems: the power electronic converter has switching process and loss. In the high-frequency PWM mode, how to reduce the switching process and loss is a problem. Key issues; the power electronic converter produces a series of pulse waves through PWM technology, which is not a continuous analog source, and the main result is the current ripple of the input and output; the fast switching characteristics of the power electronic converter bring the system High-frequency electrical (voltage, current) excitation, which conducts the analog source and load in the form of electromagnetic interference, thus causing EMI problems

[0003] The most commonly used PWM techniques in current power electronic converters are space vector PWM (SVPWM) and carrier comparison PWM (CBPWM). The switching frequency of traditional PWM technology is fixed. In the existing development, the scheme of fixed switching frequency is adjusted , through random PWM, the random change of switching frequency is used to improve EMI and auditory noise, etc., but it relies on statistical effects, and cannot predict and control the loss and current ripple

[0004] As early as 1980 at the IEEE Industrial Application Annual Conference, A. Nabae of Nagaoka University of Science and Technology in Japan first proposed a three-level midpoint clamping structure; at present, the three-level midpoint clamping structure has been widely used. Compared with the traditional two-level inverter, the three-level inverter has many advantages: the output voltage waveform harmonics of the inverter side are small, and the required filter inductance is small; the switching loss is small and the efficiency is high; it is suitable for high voltage and large Power occasions and many other advantages, however, the application of variable switching frequency in the three-level voltage source inverter is still blank

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