DC link ripple analysis on five phase pwm voltage source inverter with unbalance load
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Transcript of DC link ripple analysis on five phase pwm voltage source inverter with unbalance load
DC Link Ripple Analysis On Five Phase PWM Voltage Source Inverter With Unbalance Load
Presented by:Haryo Agung Wibowo (15862703)
Email: [email protected]
STUDY MOTIVATION
•Improve five phase inverter reliability to be able withstand working under any extreme operating condition, such as during faulted load condition
WHY WE SHOULD DO THIS?• Five phase basically give better fault tolerant
level. Motor still be able to run without loosing so much power, even motor are extremely faulted.
ELECTRICAL PERSPECTIVE• But from electrical point of view, motor fault will
rapidly elevate voltage ripple and introduce harmonic current at inverter input terminal.
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ELECTRICAL PERSPECTIVE• But from electrical point of view, motor fault will
rapidly elevate voltage ripple and introduce harmonic current at inverter input terminal.
AdditionalHarmonics
Capacitor Voltage Threshold(normally+10-12% rated Vdc)
Additional loss=In x Rc2
High Voltage Stress High Thermal Stress
ULTIMATE RESEARCH GOAL• Selecting proper capacitor size which perform
well under unbalance load
• To do this, we should concern at 3 main parameter:1.DC current ripple RMS value2.DC voltage peak to peak value3.DC current ripple harmonics spectrum
All must be analyzed under unbalance circuit operation
LITERATURE REVIEW
STARTING POINT OF ANALYSIS (I)
Easier to perform because can be resolved using algebraic manipulation.
However, DC current harmonics spectrum can not be analyzed
STARTING POINT OF ANALYSIS (II)
1. To achieve spectral decomposition, Current and voltage function must be represented by Fourier series.
2. The calculation will be exhaustive unlessmathematical analysis program is
utilized.
END
Research Background
• Electrical fault (short/open circuit) is likely to occur in the motor side
3 phase sources 3 phase rectifierAC/DC
5 phase inverterDC/AC
5 phase motor
5 Phase Inverter – Unbalance Load
1 1 1
2 2 2
3 3 3
4 1 4
5 1 5
sin
2sin 5
4sin 5
6sin 5
8sin 5
i I t
i I t
i I t
i I t
i I t
1 2 3 4 5
1 2 3 4 5
Unbalance
I I I I I
i1 i2 i3 i4 i5
In turn, it forces inverter circuit working in unbalance condition (carrying unequal current in every output phase).
5 phase inverterDC/AC
5 Phase Inverter – Unbalance Load
It causes current and voltage at capacitor terminal increase to a higher level which the magnitude
is a function of i1, i2, i3, i4, i5.
5 phase inverterDC/AC
If the capacitor specs does not account this influence, when the fault comes, component is about to produce excessive thermal stress, reduce its life time, or might be eventually burnt out
Research Objective
Therefore, it is important to analyze as well as minimize input current and voltage of the inverter (blue sign) under various circuit unbalance scenario, so optimal selection of capacitor design can be made.
idvd
This is my research area
To design capacitor size anticipating worst fault condition
Research Progress
•Literature review from past 25 year transaction•Develop research methodology:Focus how to quantify parameter that is affecting capacitor performance: Input Current Ripple Root Mean Square
(RMS) Maximum Capacitor Bus Voltage Ripple
See probability that ripple can be reduced by harmonics injection to reference signal
5 Phase Inverter – Unbalance Load
• Literature ReviewThough many paper has been published in recent 25 years, however investigating inverter input current or voltage ripple under unbalance load is getting less attention.
In addition, only few works are available concentrating on multiphase inverter
Therefore synthesizing information to develop research methodology embark from ideal three phase circuit
5 Phase Inverter – Unbalance Load
• Literature ReviewTheory developed by Cross et. al (time domain approach) and McGrath et. al (frequency domain approach) show that input ripple current can be evaluated using Fourier series.Downside: 1. To solve Fourier equation precisely, infinite number
of harmonic order must be introduced. The calculation will be exhaustive unless mathematical analysis program is utilized.
2. This method would not be able identifying which optimal switching strategy to attenuate input current or voltage ripple magnitude
5 Phase Inverter – Unbalance Load
•Literature ReviewTheory developed by Dahono et. al dictated the input ripple current can be evaluated by avoiding Fourier infinite series. The ripple equation is presented in a simple math form.
Downside: The calculation, built upon assumption that the circuit is in a perfectly balance set, whereas in practical viewpoint this is not always the case.
5 Phase Inverter – Unbalance Load
•Literature ReviewApproach proposed by Pei et. al in 2014, suggest that input ripple current under unbalance circuit condition can be analyzed through a simple math expression.Downside: 1. Ripple minimization technique is not
discussed2. The calculation only developed in three
phase circuit
Literature Review SummaryDesired Criteria
Unbalancecircuit
Avoid Fourier Series
Ripple suppressiontechnique
Five phase circuit
Cross et. al V X X X
McGrath et. al V X X X
Dahono et. al X V V V
Pie et. al V V X X
Research Objective
V V V V
THANK YOU
CONTENT
•Quick overview on Five Phase Motor Drive Train
•What is my research tell about?•Objective of my research•Literature on Five Phase Inverter•Research Plan: Research Question How do I will contribute