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Научни трудове на Съюза на учените в България-Пловдив, серия Б. Естествени и хуманитарни науки, т. XVIII, ISSN 1311-9192 (Print), ISSN 2534-9376 (On-line), 2018. Scientific researches of the Union of Scientists in Bulgaria-Plovdiv, series B. Natural Sciences and the Humanities, Vol. XVIII, ISSN 1311-9192 (Print), ISSN 2534-9376 (On-line), 2018.
ИЗСЛЕДВАНЕ НА ТРАЕКТОРИИТЕ НА ВКЛЮЧВАНЕ И ИЗКЛЮЧВАНЕ НА MOSFET ПРИ УПРАВЛЕНИЕ С АКТИВЕН И С
Светослав Иванов! Янка Иванова2, Иван ТаневЗ ТУ-Софи я, филиал Пловдив Катедра Електроника1, Катедра Електротехника2, ул."Цанко Дюстабан ов", №25 - Пловдив 4000
INVESTIGATION OF TRAJECTORIES OF SWITCHING ON AND OFF OF MOSFET DRIVING AN ACTIVE AND CONVENTIONAL DRIVER Svetoslav Ivanovl, Yanka Ivanova2,Ivan Tanev3 Faculty of Electron ics and Automation, Technical University-Sofia, (branch Plovdiv,Bulgaria
The article describes the experimental studies of the trajectories of switching on and off the MOSFET, driving DC motor. Research has been done with two different driver circuits to control the powerful transistor. One driver is conventional, and the other driver has feedback on a derivative of the current in the power circuit. A comparative analysis of the power and energy losses was made during the transition processes.
Keywords: Active driver circuit, trajectories of switching on and off, impulse control of active-inductive load with anti-EMF.
Using of active driver circuits to control powerful MOSFET transistors reduces turn-on and off times, but as a consequence also the active energy losses in the key converters (Boora, 2009). By incorporating feedback on the derivative of the the drain current di / dt in the control drivers, hard-switching reduces the electromagnetic interference (EMI) and the maximum value of the drain voltage when the transistor is switched off. This eliminates the need to include additional protective RC groups in the drain circuit (Idir, 2006). The basic circuit for realization of a current source feedback on the derivative of the current driver is shown in figure 1.
КОНВЕНЦИОНАЛЕНДРАИИЕР
Abstract
1. introduction
Fig. 1.
The magnitude of the current in the source circuit is measured and is fed as a feedback signal at the input of the driver, this can affect the rate of change of the current (Neacsu, 2001). Causes of noise generated by electromagnetic interference in solid switching of key elements are the inductances of dissipation, which are most often included sequentially on the main element in the circuit and the parasitic capacities included in the parallel of the magnetic elements, also the output capacitance of the powerful transistor. Practical switching current, voltage, and power waveforms and switching trajectory with active and high inductive load are presented in figure 2. (Rashid, 2007). On the abscissa axis there is a drain-source voltage, and on the ordinate the drain current.
Tyinral pr.iihp.i: wave loon
(highly intfiictiw In.ndj
ON 0Ff
Fig.2
The purpose of the studies made in this report is to determine the amplitude values of the current on and off of the power transistor, as well as the loss of active power and energy during the transient processes of active-inductive load control. To study the trajectory of the change of the drain current in function of the drain-source voltage uDS in the driving of a DC motor, with a conventional and active driver.
2. The experimental circuits for testing
Experimental researches were put through two experimental schemes, respectively for driving with a conventional and an active driver (Benhaddadi, 2009). Figure 3 shows a DC driving circuit with a conventional driver TC4421. For load, an executive DC motor with permanent magnets in the stator model PIC 8-6/2.5 is used. Experimental studies were performed at a supply voltage value t/supply= 30V, with frequency of control pulses 250Hz and duty cycle D = 50%.
The impulse control circuit of a DC motor with an active driver circuit is shown in fig.4. The negative current feedback is obtained from the resistor RS included in series in the supply circuit and anchor motor winding.
Fig.3
Fig.4
By using a negative current feedback, the driver circuit works as a closed control system (Park, 2003). The transfer function of the base component is represented with G = 1. The negative
feedback circuit representing the driving influence of the driver has a characteristic transfer coefficient K. The transfer coefficient of the driver circuit is described by the equation:
F =-, (1)
1 + K.
dig(t) dt
where: Ia is the change of current through the anchor while driving without a current feedback.
As a result of the action of the circuit the current through the anchor coil and the drain of the transistor ID(t) is of a form other than exponential and is determined by the equation:
G • Ia (t)
Id (t) = -
1 + K.
dIa(t) dt
(2)
3. Results of the research
Experimental researches were performed with a digital oscilloscope under laboratory conditions: first the research of the transient processes of switched off transistor is presented, followed by the transition processes when the transistor is switched on. The trajectories of drain current iD and drain-source uDS when the transistor is switching off with two drivers are shown in figures 5 and 6.
HH T ^i; _2 " -Tr^H^L t. n -T-ifc tn ; IV/H
3 +
.... -
n mÇ(
ÏL fv
ÉÏ
f UH>
Fig.5
I I
f
"!■ »n t ^viik-ihl _
"I
V-CML lMima
ov
1) fl
tVKItûn«
Fig.6
I 1
When driving with the active driver with di / dt feedback, when the voltage is changing from 23 V to the maximum value 30V, (fig.5), there is a rapid decrease in the value of the drain current iD, which reduces the active power losses in the drain of the transistor. The rate of change of the drain current diD/dt is equal to:
di dt
240mA
: 86 mA (3)
28ns ns
When the voltage of the drain of transistor reaches the value of 30V, when the driving is with a conventional driver (fig.6) the drain current iD is 1/3 of its maximum value. The drain current iD reaches zero value at voltage uDs=32V. The drain current remains unchanged until the drain voltage reaches 25V. The rate of change of the drain current di-o/dt is:
di dt
2,6 A 12ns
217
mA
ns
(4)
Trajectories of the drain current iD and the voltage drain-source uDS, when the transistor is switched on, are shown in figures 7 and 8.
1
s 1 si
\ j
V
Г! ю: 1 1 !И i
LMJ I L LKJ lj
Ti LOi'^ T
V
T-OfliKfTWP
I
(Л
I 1
л йт Htm'
4 ill
ЛЯ lIStlY М«1Ж
~r
VI (V
.L- OOlllJ
T<H1 -.tortW=i
I
(Л i
9
>i 0"
ЛЯ lIStlY iT
Fig.7 Fig.8
Driving with the active driver with di/dt feedback (fig.7), when the transistor switches on, the voltage drain-source uDS is changing from 30V to 12,8V(dx=17,2V), for time equal to 340ns. For this time interval the drain current iD reaches maximum value of 220mA (du=22,00mV).
With conventional TC4421 driver control, unlike current and voltage trajectories when the transistor is switching off, here when switching on, the waveform is represented from right to left (fig.8). There is a graph of the transition process in which the drain voltage changes from 30V to 12.8V for time equal to 360ns. The amplitude of the current is 1,14А. Compared to active driver control, the maximum current value, when the load is switched on, is approximately 16 times greater.
4. Conclusion
A comparative analysis of the MOSFET trajectories is performed when driving with a conventional and an active driver. The proposed and tested driving circuit is suitable for controlling power circuits with active-inductive load. The practical application of this driver scheme will improve the electromagnetic compatibility between power schemes and their control systems. When driving with the active driver with a di/dt feedback at the same time the current reaches a zero value, and the voltage reaches maximum value equal to the value of the supply voltage. With the active driver, the transition process has a higher attenuation than conventional driver control. This means that the time of the transition process at switch-on will be less, and hence the energy loss.
Literature
Benhaddadi, M., Olivier G., Labrosse D., Tetrault P.: (2009a) "Premium efficiency motors and energy saving potential,". IEEE International electric machines and drives conference, IEEE_IEMDC, Miami, USA, 2009.
Boora, A., Arash and Zare, Firuz and Ghosh, Arindam (2009) Efficient Voltage/Current Spike Reduction by Active Gate Signaling. In: Proceedings of the Electromagnetic Compatibility Symposium, Adelaide 2009, 16-18 September 2009, Lakes Hotel Resort, Adelaide.
Idir, N.; Bausiere, R.; Franchaud, J.J. ;"Active gate voltage control of turn- on di/dt and turn-off dv/dt in insulated gate transistors" IEEE Transactions on Power Electronics, Volume 21, Issue 4, July 2006 Page(s):849 - 855.
Neacsu, D., "Active Gate Drivers for motor control applications", IEEE PESC 2001, Vancouver, CANADA, June, 17-21, 2001.
Shihong Park, Thomas M. Jahns, Flexible dv/dt and di/dt Control Method for
Insulated Gate Power Switches, IEEE transactions on industry applications, vol. 39, no. 3, may/june 2003, pp. 55-59.
Rashid, M. Power Electronics Handbook. San Diego, USA, 2007. ISBN: 978-0-088479-7.
Контакт с авторите:e-mail: etehsv@gmail.com, yankakiss777@abv.bv, mastervanio@yahoo.de
