Pulse width controller of program sinusoidal wave

Abstract

The invention discloses a PWM controller of program sin waves, which pertains to the technical field of the frequency conversion control of a power source, wherein, a ring counter circularly inputs 0-503 addresses for a sin wave data memory by address signals; an EEPROM reads out the sin wave data according to the addresses; the sin wave data is sent to a total controller by IO3-IO8, meanwhile, signals are sent to a differential transforming circuit to reach a 'pulse-width signal controller' by IO1-IO2; the pulse-width signal is sent to the total controller, and at the same time, after another path of input pulse control signals are sent to a combination controller to be processed, the pulse-width signals are divided into two paths to be respectively sent to the pulse-width signal controller and a binary decoder; then the sin wave data is sent to the total controller by the sin wave data memory; two synchronizing signals are modulated and processed in the total controller and an ASPWM control signal is output to drive power devices. The PWM controller of the invention is simple and reliable, has low cost and is beneficial to the popularization of the small and medium power frequency converters.

Description

technical field [0001] The invention belongs to the technical field of power frequency conversion control, and in particular relates to a pulse width controller of a program sine wave. Background technique [0002] In the field of power electronics technology, the power switching devices in the 1970s were only ordinary thyristors used in industrial inverters. Due to the shortcomings of thyristors in many aspects such as high price, inability to turn off by themselves, and low operating frequency, the The application development of the inverter [now known as the frequency converter] was limited. At that time, the forced commutation of the thyristor inverter was very difficult, and the operating frequency was too low, which greatly reduced the performance of the inverter. With the advancement and development of power electronics technology and the emergence of BJT (power transistor) power devices, power electronics has new opportunities for development. In particular, the eme...

AI Technical Summary

Problems solved by technology

[0005] 2. Sine wave pulse width modulation: (SPWM), due to the three reasons of the SPWM frequency conversion mechanism itself, it cannot effectively suppress high-order harmonics: (1) In engineering applications, regular sampling methods or special-purpose methods are often used to generate SPWM waveforms. Large-scale integrated circuit devices cannot guarantee that the waveform area of ​​the pulse width modulation sequence wave is completely equal to the area of ​​each segment of the sine wave; (2) When implementing control, in order to prevent the simultaneous conduction When the upper and lower devices of the same bridge arm perform complementary work, a conduction time-delay link is set

The appearance of time lag will inevitably lead to distortion of the SPWM waveform output by the inverter (the above-mentioned 1 and 2 frequency conversion technologies are quoted from "AC speed control system" written by Chen Minxun)

(3) During the SPWM waveform generation process, N / 2 sequence pulses with different on-times will be generated to simulate sine waves. Since the difference between the widest and narrowest pulses is more than ten to dozens of times, the on-time of the narrowest pulse It must be greater than the minimum on-time allowed by the power device. Because the narrowest pulse is very narrow, it limits the improvement of the carrier ratio N. The lower the carrier ratio N, the higher the high-order harmonic component

It is too uneconomical to recover the investment cost in 20 years

Mainly affected by the high cost of frequency conversion controllers, the price of products used in low-power frequency converters is difficult for consumers to accept

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