67results about How to "Modulation method is simple" patented technology

The invention relates to a distributed pulse width modulation method based on multi-core cooperative work. The hardware architecture adopts the master-slave control mode, which consists of a main module and several sub-modules. The main module and the sub-modules are connected by 485 communication. Each sub-module contains an H-bridge unit, and each H-bridge unit is cascaded. After being output by the LC filter circuit, the method is specifically implemented as follows: the main module parameter initialization; the main module updates the status of the sub-modules and calculates the total error value of the current output voltage; The output sub-module calculates the delay time and outputs a new level; the sub-module is fault-protected. The present invention effectively improves the control ability and computing ability of the whole equipment. The main module controls the sub-modules through communication and interaction. The stability is higher than the traditional modulation method.

The invention relates to a synchronization active type islanding detection system and a method based on M sequence modulation and variance estimation. The detection system comprises a synchronizationinverter, a synchronization switch, a voltage Hall sensor arranged on a synchronization communal join point, a digital signal processor connected with the synchronization inverter, the synchronizationswitch and the voltage Hall sensor. The detection method is to utilize the pseudo-random signal M sequence of the communication technique, modulate the modulation wave of the inverter according to the distribution law of the M sequence, so as to make the output have the characteristics of the M sequence, and thus the output signals also have the characteristics of random signals. During synchronizing, the voltage of the synchronization communal join point is controlled by a power network and the randomness is small; therefore the obtained variance value of the random sequence is very small; when islanding, the voltage of the synchronization communal join point is determined by the output of the inverter, the output of the inverter is modulated through the digital signal processor and havethe characteristics of the random signals, so the variance value is significantly increased. During detecting, a variance threshold value is set, and islanding can be determined when the detected variance is more than the threshold value. The synchronization active type islanding detection system and the method has the advantages of simple arithmetic, low cost, small effects to harmonic waves ofthe output power and small islanding detection blind zone.