Study on a New Type of HVDC Flexible Digital Pulse Width Modulated Carrier Frequency Selection

2015 ◽  
Vol 740 ◽  
pp. 503-506
Author(s):  
Qing Liang Qin
Keyword(s):  
Carrier Frequency ◽  
Control Method ◽  
Digital Signal ◽  
Sine Wave ◽  
Control Signal ◽  
Frequency Change ◽  
Pulse Modulation ◽  
Frequency Selection ◽  
Analog To Digital Conversion ◽  
Digital Pulse

For multi_level multi_module in the flexible HVDC converter (MMC) module capacitor control algorithm is commonly based on nearest voltage level modulation (NLM), this algorithm requires the decimal part of the input sine wave for analog-to-digital conversion by digital signal (digital pulse modulation, referred to as DPWM),in the choice of hysteretic DPWM control signal is better, if the input triangle carrier wave frequency selection is not good, in each digital signal level will cause the output frequency of DPWM is not stable, some DPWM frequency is too high, and some DPWM has no output. In order to solve this problem, to meet the requirements of control precision, the carrier frequency change DPWM triangular wave, the output ideal control signal, the output control signal is analyzed, put forward how to carry out DPWM frequency selection. Through the simulation certified the feasibility of this method, the control method of downloading to the field programmable gate array (FPGA) chip, the results of the actual control operation show that this method can optimize the control of flexible HVDC.

Design of Comprehensive Test Instrument Based on FPGA and Cortex-M0

2013 ◽  
Vol 312 ◽  
pp. 583-587
Author(s):  
Liang Jun Yu ◽  
Li Hua Sun ◽  
Cui Cui Huang
Keyword(s):  
Frequency Characteristic ◽  
High Speed ◽  
Digital Signal ◽  
Sine Wave ◽  
Signal Frequency ◽  
Voltage Amplitude ◽  
Amplitude Frequency Characteristic ◽  
Amplitude Measurement ◽  
Analog To Digital Conversion ◽  
Test Module

The design consists of three modules: the voltage amplitude measurement module, the level oscillator module and the amplitude-frequency characteristic test module. The voltage amplitude measurement module uses AD817 to consist three-stage amplifier. The magnification of each level can be adjusted for 1 times/10 times. At the same time, the author uses the Cortex-M0 for controlling the relay switch to achieve automatic range conversion. The principle of DDS is adopted in the level oscillator module. FPGA is used for realizing the phase accumulator, the phase modulator, the sine ROM look-up table. Digital signal is finally outputted by high-speed analog-to-digital conversion chip DAC900. Then, by controlling the 6-channel relay switch to make the magnification in the amplifying circuit,which can be adjusted step-by-step from-30dB to 20dB. Through outputting sine wave whose amplitude is fixed, but frequency is variable to the network under test, amplitude-frequency characteristic test module measures the relation betthe authoren the amplitude change of the output signal and the signal frequency to obtain the amplitude-frequency characteristics of the network under test..

Hysteretic Control Technology in New Flexible HVDC

2015 ◽  
Vol 740 ◽  
pp. 495-498 ◽  
Author(s):  
Qing Liang Qin ◽  
Xiao Hui Yao ◽  
Dian Zhang
Keyword(s):  
Pulse Width ◽  
Fractional Part ◽  
Digital Signal ◽  
Sine Wave ◽  
Multilevel Converter ◽  
Frequent Change ◽  
Digital Pulse ◽  
Field Programmable ◽  
Hysteretic Control ◽  
The Stability

The nearest level modulation (NLM) is commonly used in the multi-level multi-module converter (MMC), which need to convert the fractional part of the input sine wave to the digital signal (DPWM). However, the narrow pulse width of digital signal , the frequent change of the digital signal and the frequent instability of output are caused by the sensitive fractional portion of the input, which push Multilevel converter into the position where it has to operate in high frequency and be unstable. In order to solve the problem mentioned above, this paper provides a way called hysteresis comparison to meet the control requirements of precision, adopting the comparison between the fractional part and triangular carrier wave. The approach this study provides is called hysteresis comparison which not only can ensure the stability of the output of the digital signal but also can be able to obtain better digital pulse width by adjusting hysteresis threshold trigger. At the same time, it could ensure the stability and pulse width of the output by means of reducing the frequency of the digital output. The feasibility of this approach has been certified by the simulation of field-programmable gate array (FPGA). Apparently, the actual results show that this method can optimize the control of HVDC Flexible.

Demonstration of digital pulse modulation of a grating-surface-emitting diode laser

1990 ◽  
Vol 26 (20) ◽  
pp. 1695
Author(s):  
N.W. Carlson ◽  
D.R. Patterson ◽  
P.J. Stabile ◽  
S.K. Liew ◽  
D.P. Bour ◽  
...  
Keyword(s):  
Diode Laser ◽  
Pulse Modulation ◽  
Digital Pulse

Adaptive composite control method of permanent magnet synchronous motor systems

2017 ◽  
Vol 40 (11) ◽  
pp. 3345-3357 ◽  
Author(s):  
Zhenxing Sun ◽  
Shihua Li ◽  
Jiegao Wang ◽  
Xinghua Zhang ◽  
Xiaohui Mo
Keyword(s):  
Control Method ◽  
Permanent Magnet Synchronous Motor ◽  
Digital Signal ◽  
Cascade Control ◽  
Current Loop ◽  
Single Loop ◽  
Control Scheme ◽  
Control Schemes ◽  
Relative Differences ◽  
Compensation Design

With the development of digital signal processes, the relative differences of PMSM single loop in control periods between the speed loop and current loops are becoming smaller or even vanishing. Therefore, cascade control schemes seem to be unnecessary. In addition, considering the effects of disturbances and the variety of moments of inertia, this paper proposes a scheme using an adaptive non-cascade control method to design the controller, which merges speed loop and q-axis current loop into one single loop. First, an extended state observer (ESO) is employed to estimate the disturbances of the system. The estimated value is used in the feedforward compensation design to improve the capability of system anti-disturbance. Then, considering the performance degradation caused by inertia change, an adaptive control scheme is developed. By using inertia identification technology, the feedforward compensation gain can be tuned automatically according to the identification value. Several groups of simulations and experiments are carried out and the results demonstrate the effectiveness of the proposed scheme.

The control method for the multi-phase traffic model

2016 ◽  
Vol 27 (10) ◽  
pp. 1650111
Author(s):  
Yi Liu ◽  
Rong-Jun Cheng ◽  
Yan-Qiang Ma ◽  
Hong-Xia Ge
Keyword(s):  
Traffic Control ◽  
Control Method ◽  
Turning Points ◽  
Control Signal ◽  
Two Phase ◽  
Optimal Velocity ◽  
Car Following Model ◽  
The Stability ◽  
Improved Model ◽  
Multi Phase

Based on multi-phase car-following model proposed by Nagatani, the control theory method is used to analyze the stability of the model. The optimal velocity function is improved to have more turning points. The original optimal velocity with one turning point shows two-phase traffic, while the improved model with [Formula: see text] turning points exhibits [Formula: see text] phase traffic. Control signal is added into the model. Numerical simulation is conducted to show the results for the stability of the model with and without control signal.

The Test Equipment Based on Single Chip Micro (SCM) of Volt-Ampere Characteristic of CT

2014 ◽  
Vol 556-562 ◽  
pp. 1726-1729
Author(s):  
Bai Fen Liu ◽  
Ying Gao
Keyword(s):  
Output Voltage ◽  
Sine Wave ◽  
Test System ◽  
Control Signal ◽  
Test Equipment ◽  
Single Chip ◽  
Test Technique ◽  
Computer Technique ◽  
Peripheral Equipment ◽  
The Future

Nowadays, various test equipment tend to be more intelligent, the test equipment of the volt-ampere characteristic of CT is so too. As the development of the electronics, VLSI(SCM) is manufactured. The purpose of our project is to scheme out a intelligent test system by the computer technique and the test technique. This equipment is mostly made of the SCM system and the peripheral equipment. We control the output of the digital transformer by SCM. The output voltage can make the TL494 create PWM wave. The wave is the control signal of the main circuit. The output wave of the main circuit is the sine wave, and the value of the output can be amended automatically. Compared with the traditional equipment, this equipment is smaller and use less energy, but its function is more powerful. It can be programmable. We can take it more expediently. So, this kind of equipment can be used widely in the future.

Sign in / Sign up

Export Citation Format

Share Document