Procedure for determining the stray capacitance of a switching circuit node

**Authors:**Naude, Tonya**Date:**2009-02-26T12:21:12Z**Subjects:**Electric capacity , Capacitance meters , Electromagnetic interference , Switching circuits , DC-to-DC converters**Type:**Thesis**Identifier:**uj:8169 , http://hdl.handle.net/10210/2174**Description:**M.Ing. , This study focuses its attention on conducted common mode EMI. Common mode current is the current that flows from an electrical circuit to a zero reference plane and back to the circuit again. It is known that the manner in which the common mode current flows is through stray capacitances that form between the electrical circuit and the zero reference. This study was aimed at developing a method to measure the value of the stray capacitance of a switching circuit. Determining the value of the stray capacitance by taking physical measurements on a circuit board is a challenge for a number of reasons, one of which is that great care should be taken not to add to the stray capacitance by means of the measuring equipment. By measuring the value of the stray capacitance, it will be possible to model the occurrence of Common Mode EMI better and more accurately. This could, in turn, lead to a reduction in EMI. Any body of an arbitrary shape, size and material exhibits a self-capacitance with respect to a zero reference frame. This principle, together with the principle of conservation of charge, also applies to electrical components, or circuits as a whole. The experimental work was performed on a buck DC-DC converter. The circuit was simplified to aid in analysis. By varying the value of an external capacitance and taking basic measurements, it is then possible to uniquely determine the absolute values of the self-capacitances. For every pair of external capacitance values placed in the circuit (of which one can be =0pF), a value for stray capacitance is calculated. Many data points were recorded with many different external capacitors in the circuit, resulting in a variety of stray capacitance values. In order to obtain a single value, a weighted mean of all the values was calculated. The values obtained in this proposed method of measuring the stray capacitance compares well with that obtained using the Finite Element Method. The advantage of the method presented here is that the self-capacitances are determined under the actual operational conditions, no specialised equipment is required and no unique handling of parasitics is needed. The method relies on very simple measurements and no complex data manipulations are required.**Full Text:**

**Authors:**Naude, Tonya**Date:**2009-02-26T12:21:12Z**Subjects:**Electric capacity , Capacitance meters , Electromagnetic interference , Switching circuits , DC-to-DC converters**Type:**Thesis**Identifier:**uj:8169 , http://hdl.handle.net/10210/2174**Description:**M.Ing. , This study focuses its attention on conducted common mode EMI. Common mode current is the current that flows from an electrical circuit to a zero reference plane and back to the circuit again. It is known that the manner in which the common mode current flows is through stray capacitances that form between the electrical circuit and the zero reference. This study was aimed at developing a method to measure the value of the stray capacitance of a switching circuit. Determining the value of the stray capacitance by taking physical measurements on a circuit board is a challenge for a number of reasons, one of which is that great care should be taken not to add to the stray capacitance by means of the measuring equipment. By measuring the value of the stray capacitance, it will be possible to model the occurrence of Common Mode EMI better and more accurately. This could, in turn, lead to a reduction in EMI. Any body of an arbitrary shape, size and material exhibits a self-capacitance with respect to a zero reference frame. This principle, together with the principle of conservation of charge, also applies to electrical components, or circuits as a whole. The experimental work was performed on a buck DC-DC converter. The circuit was simplified to aid in analysis. By varying the value of an external capacitance and taking basic measurements, it is then possible to uniquely determine the absolute values of the self-capacitances. For every pair of external capacitance values placed in the circuit (of which one can be =0pF), a value for stray capacitance is calculated. Many data points were recorded with many different external capacitors in the circuit, resulting in a variety of stray capacitance values. In order to obtain a single value, a weighted mean of all the values was calculated. The values obtained in this proposed method of measuring the stray capacitance compares well with that obtained using the Finite Element Method. The advantage of the method presented here is that the self-capacitances are determined under the actual operational conditions, no specialised equipment is required and no unique handling of parasitics is needed. The method relies on very simple measurements and no complex data manipulations are required.**Full Text:**

Controlled power flow capacitive divider for electric power tapping

- Jimoh, A. A., Munda, J., Britten, A. C., Nicolae, Dan-Valentin

**Authors:**Jimoh, A. A. , Munda, J. , Britten, A. C. , Nicolae, Dan-Valentin**Date:**2006**Subjects:**Electric power systems , Capacitance meters**Language:**English**Type:**Conference proceedings**Identifier:**http://hdl.handle.net/10210/15982 , uj:15724 , ISBN: 1-4244-0121-6 , Citation: Jimoh, A.A. et al. 2006. Controlled power flow capacitive divider for eletric power tapping. In: Proceedings of the 12th International Power Electronics and Motion Control Conference, 30 August-1st September, 2006, Portoroz. DOI: 10.1109/EPEPEMC.2006.4778611-1477**Description:**Abstract: Capacitive divider systems for tapping electric power from high voltage transmission lines are known to exhibit certain detrimental problems of stability, sub-resonance harmonic oscillations, and ferroresonance when coupled with non-linear loads. On the other hand, they can improve reactive power flow, power factor and contribute to improved harmonic filtration of the larger power system. This paper, therefore, proposes a controlled power flow conditioner as an essential integral component of a capacitive divider system to control power transfer between the high voltage transmission line, capacitive divider system, and the load. The ultimate objective of this conditioner is to mitigate or minimize the attendant problems associated with coupling the system to the load, and optimize the derivable benefits to the larger network.**Full Text:**

**Authors:**Jimoh, A. A. , Munda, J. , Britten, A. C. , Nicolae, Dan-Valentin**Date:**2006**Subjects:**Electric power systems , Capacitance meters**Language:**English**Type:**Conference proceedings**Identifier:**http://hdl.handle.net/10210/15982 , uj:15724 , ISBN: 1-4244-0121-6 , Citation: Jimoh, A.A. et al. 2006. Controlled power flow capacitive divider for eletric power tapping. In: Proceedings of the 12th International Power Electronics and Motion Control Conference, 30 August-1st September, 2006, Portoroz. DOI: 10.1109/EPEPEMC.2006.4778611-1477**Description:**Abstract: Capacitive divider systems for tapping electric power from high voltage transmission lines are known to exhibit certain detrimental problems of stability, sub-resonance harmonic oscillations, and ferroresonance when coupled with non-linear loads. On the other hand, they can improve reactive power flow, power factor and contribute to improved harmonic filtration of the larger power system. This paper, therefore, proposes a controlled power flow conditioner as an essential integral component of a capacitive divider system to control power transfer between the high voltage transmission line, capacitive divider system, and the load. The ultimate objective of this conditioner is to mitigate or minimize the attendant problems associated with coupling the system to the load, and optimize the derivable benefits to the larger network.**Full Text:**

Complete analysis of a multilevel inverter based on 3 level NPC/H- bridge topology for photovoltaic application

- Wanjekeche, T., Nicolae, Dan-Valentin, Jimoh, A. A.

**Authors:**Wanjekeche, T. , Nicolae, Dan-Valentin , Jimoh, A. A.**Subjects:**Bridge circuits , Capacitance meters , Electric power measurement**Language:**English**Type:**Article**Identifier:**http://hdl.handle.net/10210/18262 , uj:15978 , Citation: Wanjekeche, T., Nicolae, D.V. & Jimoh, A.A. 2010 Complete analysis of a multilevel inverter based on 3 level NPC/H- bridge topology for photovoltaic application. IEEE**Description:**Abstract: The cascaded NPC/H- bridge inverter is first analyzed by establishing a new switching model based on a derived control law, then using the model a general model using state space technique is obtained. A new and accurate average model is developed using abc to dqo transformation technique. A small signal model is developed by linearizing all the state variables around their quiescent operating points. The small signal model is used to study the effects of various control feedback variables on the dynamic performance of the PV- Grid system. Based on the transfer function developed feedback control loop is developed to improve the dynamic response of the system as well as voltage balancing of the DC link. Simulation results are provided to validate the analytical models.**Full Text:**

**Authors:**Wanjekeche, T. , Nicolae, Dan-Valentin , Jimoh, A. A.**Subjects:**Bridge circuits , Capacitance meters , Electric power measurement**Language:**English**Type:**Article**Identifier:**http://hdl.handle.net/10210/18262 , uj:15978 , Citation: Wanjekeche, T., Nicolae, D.V. & Jimoh, A.A. 2010 Complete analysis of a multilevel inverter based on 3 level NPC/H- bridge topology for photovoltaic application. IEEE**Description:**Abstract: The cascaded NPC/H- bridge inverter is first analyzed by establishing a new switching model based on a derived control law, then using the model a general model using state space technique is obtained. A new and accurate average model is developed using abc to dqo transformation technique. A small signal model is developed by linearizing all the state variables around their quiescent operating points. The small signal model is used to study the effects of various control feedback variables on the dynamic performance of the PV- Grid system. Based on the transfer function developed feedback control loop is developed to improve the dynamic response of the system as well as voltage balancing of the DC link. Simulation results are provided to validate the analytical models.**Full Text:**

Performance analysis of capacitance compensated dual stator winding synchronous reluctance machine

- Ogunjuyigbe, A. S. O., Jimoh, A. A., Nicolae, Dan-Valentin, Obe, E. S.

**Authors:**Ogunjuyigbe, A. S. O. , Jimoh, A. A. , Nicolae, Dan-Valentin , Obe, E. S.**Date:**2010**Subjects:**Capacitance meters , Synchronous machinery , Torque**Language:**English**Type:**Article**Identifier:**http://hdl.handle.net/10210/18633 , uj:16024 , ISSN:1827-6660 , Citation: Ogunjuyigbe, A.S.O. et al. 2010. Performance analysis of capacitance compensated dual stator winding synchronous reluctance machine. International Review of Electrical Engineering,5(2), April 2010:437-446**Description:**Abstract: Synchronous reluctance machine with simple salient rotor are known to have poor power factor because they have a low effective reactance ratio. This paper used a 3 phase auxiliary winding and balanced capacitance compensation to ifluence the effective reactance ratio of a synchronous reluctance machine with simple salient rotor structure, such that its power factor and torque/ampere performance is improved. A mathematical model and dq equivalent circuit suitable for dynamic and steady state analysis was developed and used to study the synchronous operation of this machine.Analytical as well as experimental results for a 4-pole, 36 slots simple salient rotor reluctance machine showed that the effective reactance ration increased with the capacitance size, and the machine operated at a maximum power factor of 0.969 without altering the geometry of the rotor. the torque per ampere of the machine also improved with the size of capacitor attached to the auxilary winding.**Full Text:**false

**Authors:**Ogunjuyigbe, A. S. O. , Jimoh, A. A. , Nicolae, Dan-Valentin , Obe, E. S.**Date:**2010**Subjects:**Capacitance meters , Synchronous machinery , Torque**Language:**English**Type:**Article**Identifier:**http://hdl.handle.net/10210/18633 , uj:16024 , ISSN:1827-6660 , Citation: Ogunjuyigbe, A.S.O. et al. 2010. Performance analysis of capacitance compensated dual stator winding synchronous reluctance machine. International Review of Electrical Engineering,5(2), April 2010:437-446**Description:**Abstract: Synchronous reluctance machine with simple salient rotor are known to have poor power factor because they have a low effective reactance ratio. This paper used a 3 phase auxiliary winding and balanced capacitance compensation to ifluence the effective reactance ratio of a synchronous reluctance machine with simple salient rotor structure, such that its power factor and torque/ampere performance is improved. A mathematical model and dq equivalent circuit suitable for dynamic and steady state analysis was developed and used to study the synchronous operation of this machine.Analytical as well as experimental results for a 4-pole, 36 slots simple salient rotor reluctance machine showed that the effective reactance ration increased with the capacitance size, and the machine operated at a maximum power factor of 0.969 without altering the geometry of the rotor. the torque per ampere of the machine also improved with the size of capacitor attached to the auxilary winding.**Full Text:**false

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