Derating

In previous chapters, we discussed the converter with or without fault. The common similarity between them is that they continue to operate without reduction of their nominal specification. In this chapter, uninterrupted operation of a faulty power conversion system with catastrophic damages in some of its parts is investigated. It is shown that a faulty electric power converter can continue to work with degraded specifications. This algorithm is named derating for accessibility. This technique can be used for both a faulty system because of its uninterrupted operation and a normal system because of extensive life time. Algorithms for derating of a faulty electric machine and a power supply are described. Derating for increasing the useful life of a motor drive system is presented. A novel method for switching frequency selection in a switching power supply is proposed based on derating concept. Derating is introduced as a technique to compensate additional losses in an electric power converter operating in harsh environment (for example: a motor drive which is supplied with a non sinusoidal voltage waveform). Industrial examples are presented in details for better understanding of the derating concept. Some of the presented examples contain novel idea for derating and others are well known in industry.

2014 ◽  
Vol 568-570 ◽  
pp. 1217-1220
Author(s):  
Shu Lin Liu ◽  
Li Li Qi

In order to improve the efficiency of the switching power supply in whole load range, the controller with PWM, PFM and BURST operating modes is designed in this paper, which changes the operation mode automatically according to the load. The operating principle and the advantages and disadvantages of the three operating modes are analyzed and compared. PWM mode is used in heavy load; PFM mode is used in light load to reduce switching losses by reducing the switching frequency and BURST mode is used at the standby time to further reduce switching losses. The main control module is designed and simulation results verify the feasibility of the designed circuit.


2013 ◽  
Vol 385-386 ◽  
pp. 1305-1308
Author(s):  
Pan Feng Guo ◽  
Jian Song ◽  
Hong Zhang ◽  
Xin Li ◽  
Rui Lu

Because of its high reliability and stable output, switching power supply is widely used in power electronic systems, but it is can not be ignored that its self-generated electromagnetic has a profound effect on the whole system. In order to suppress conducted interference generated by switching power supply, this article proposed a cascaded technology about the integrated EMI filter, and a simulation is carried out for the power converter output waveform. Experimental results show that this cascaded technology about the integrated EMI filter has a good inhibition on the harmonic.


2013 ◽  
Vol 787 ◽  
pp. 726-730 ◽  
Author(s):  
Zhi Hong Zhang ◽  
Bao Feng Zhang ◽  
Guang Quan Li

With the increase of switching frequency of power switch, EMI noise pollution becomes more and more serious. In order to solve this problem, in this paper, the switch power supply filter and passive EMI filter, active EMI filter is studied. It mainly research active EMI filter with feed forward , non-inductive current detection device of active EMI filter and active EMI filter for three-phase inverter motor. To solve this problem which is that EMI noise pollution has become more serious along with the increase of switching frequency switch power supply, the increasingly serious pollution make the EMI filter technology have a wide range of applications and put forward higher request to filter technology


2013 ◽  
Vol 336-338 ◽  
pp. 1186-1189
Author(s):  
Zhu Lei Shao ◽  
San Tang

Aiming at the problem of switching power supply stable output, a push-pull switching power supply was designed. the switching frequency is 100kHZ and the output voltage is 5V. System model of the push-pull switching power supply is established on PSpice, and research on the output performance of the push-pull switching power supply. By the parameter sweep analysis of load, the push-pull switching power supply can stabilize output in full load and light load conditions, and load regulation rate comply with the design requirements.


2011 ◽  
Vol 474-476 ◽  
pp. 883-887
Author(s):  
Hong He ◽  
Shuai Bao ◽  
Hang Li ◽  
Da Jian Zhang ◽  
Ming Feng Hou

Along with the power electronic technology constantly to high frequency change, miniaturization, direction, switching power supply the electromagnetic compatibility problems appeared more and more important. This paper mainly analyses the switch power electromagnetic interference source and the coupling channels, and with half a bridge type switch power converter for example analyses of switch power supply conducted interference. On the basis of existing circuit model, calculates and analyzes the an active filter, thus for suppression of switch power supply conducted interference provide theoretical basis.


Author(s):  
C. Vidhya ◽  
V. Ravikumar ◽  
S. Muralidha

: The objective of this paper is to implement an ac link universal power converter controlled BLDC motor for medical applications. The ac link universal power converter is a soft switched high frequency ac link converter, created using the parallel combination of an inductor and a capacitor. The parallel ac link converter handle the ac voltages and currents with low reactive ratings at the link and offers improved power factor, low power consumption, more efficiency and less weight on comparison with the traditional dc link converter. Because of the high throughput, BLDC motors are preferred widely medical applications. A modulation technique called Space Vector Pulse Width Modulation (SVPWM) is used to generate the three phase power for the BLDC motors from the input DC supply. To validate the proposed system, simulations are performed in MATLAB – Simulink and an experimental prototype is constructed to supplement the simulation results.


2013 ◽  
Vol 834-836 ◽  
pp. 1221-1224
Author(s):  
Hong Zhuan Cai ◽  
Li Bai

Switching power supply is an important field of application of power electronic technology, the high frequency switching DC power supply with high efficiency, small size, light weight and other advantages obtain the widespread application. The application of synchronous rectifier technology, photoelectric coupling isolation technology and the active clamp forward converter design high frequency switching power supply with 16~40V DC input and 5V/100W DC output . its operational principle is analyzed, and using LM5026 control chip describes design method of switching power supply.


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