Real-Time Implementation of a Single Phase Asynchronous Motor
Drive Feeding within an Open Energy Source
ESSAMUDIN A. EBRAHIM1,, EMAD A. SWEELEM2,
¹Power Electronics and Energy Conversion Department
²Photo-voltaic Department,
Electronics Research Institute,
Joseph Tito St., Huckstep, Qism El-Nozha, Cairo Governorate, 12662 Cairo
EGYPT
Abstract: - A modified nanogrid (MnG) is a very small scalable grid with a low power single-input multi-output
(SIMO) inverter. This inverter simultaneously produces both AC and DC currents, such as the switched boost
inverter (SBI) and the z-source inverter. These inverters are suitable for low-power loads such as home appliances
that use fractional horse-power motors as single-phase asynchronous drives. Thus, this article proposes a single-
phase induction motor powered from a modified nanogrid that involves multiple types of inverters such as a SBI
and a ZS inverter. The modified nanogrid is mainly dependent on photovoltaic (PV) as a renewable
resource. Thus, this manuscript involves a full design for this proposed grid with its maximum power point
tracking (MPPT) and the mathematical models for motor drive with both a SBI and a ZSI. Time-varying speed
trajectories are proposed to test the robustness of the proposed drives relative to the fluctuation of PV-parameters
like its irradiance. Test results are obtained using the Matlab/ Simulink software package and a comparison with
the traditional sinusoidal pulse width modulation (SPWM) inverter as a single-input single-output inverter
(SISOI). The results indicate that the proposed single-input multi-output inverters are suitable for driving these
motors through start-up and operation, although the DC-link voltage is minimized. Furthermore, the proposed
system is experimentally implemented with OPAL RT-4510v real-time hardware in the loop (HIL), rapid control
prototyping, and OP-8660 HIL controller and data acquisition platform.
Key-Words: - DC-modified nanogrid (DCMnG), Hardware in the loop (HIL), Open energy source (OES), Real-
time simulator, Single input multi-output inverter (SIMO), Switched boost inverter (SBI), Z-source inverter (ZSI)
Received: April 25, 2021. Revised: April 22, 2022. Accepted: May 25, 2022. Published: June 25, 2022.
1 Introduction
Induction motors are still widely used in most
industrial, commercial and electrical household
applications. They are robust, cost-effective,
maintenance-free, and have a high power-to-weight
ratio [1]-[3]. In contrast, single-phase fractional
horsepower induction motors are widely used in a
variety of household appliances such as refrigerators,
washing machines, and water pumping [4]-[9].
There are several types of these motors are
classified according to their starting such as:
capacitor starting, capacitor-starting capacitor
running, split-phase and shaded pole induction
motors [10]. In the past and to date, many efforts have
been made to improve and enhance the performance
of these motors as variable speed drives. These
proposed techniques use a field-oriented vector
control for speed tracking such as in [11]-[15].
However, these motors can be powered from the
main grid or from an open energy source (OES). The
open energy source is a combination of a huge
number of DC-nano-grids (DCnGs) that have
connected to one another via a DC-link. They contain
renewable resources – such as PV, wind, fuel cells,
batteries – which are used to power both the DC and
AC loads through converters. The traditional nano-
grid involves a two-stage converter. It is known as a
single-input single output (SIMO) converter. This
type uses many components and requires many
circuitry to protect [16]-[17]. On the other hand, the
DCMnGs involve single-input multi-output
converters that simultaneously produce both the DC
and AC currents [18],[19]. However, the DC input
voltage to the inverter plays a significant rule on its
AC output voltage. If the DC-nanogrid is a
standalone/ off-grid connection, its AC-output
voltage must be well controlled to ensure the
sufficient voltage value needed to control the speed
and torque of these motors. Most renewable energy
sources such as PVs produce a variable DC-voltage
based on their irradiation. This DC-voltage is directly
proportional to the input radiation. Therefore, if it is
cloudy or dark, the AC output voltage will be
reduced. Depending, the performance of the
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DOI: 10.37394/232016.2022.17.13
Essamudin A. Ebrahim, Emad A. Sweelem
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asynchronous motor will be affected during starting
and running. Thus, it should increase the AC-input
voltage to maintain the torque and speed with proper
values keeping the motor running safe with the load.
The SBI and ZSI can do that [20]-[25]. Thus, this
article introduces a single-phase induction motor
(SPIM) with starting capacitor - powered from an
open energy source through a single input multi-
output inverter (SIMOI). The voltage/ frequency
control technique is offered to maintain the internal
torque constant through speed change. A robust DC-
link voltage controller is provided to maintain the
DC-link voltage of the SBI constant. In addition, z-
source inverter will be compared with the SBI and the
conventional (SPWM) as a single-input single-output
(SISO) inverter.
The best will be implemented in real-time
with the help of OPAL RT-hardware in the loop
(HIL) with rapid control prototyping platform. This
real-time emulator will be connected through OPAL
OP8660 HIL controller and data acquisition module.
The real time results are also obtained with the help
of the Matlab/ Simulink program for a gradual speed
trajectory with different PV-supplies dependent on
their insolation. This manuscript is organized a long
the following lines: section 1 is introduction. The
proposed system with SIMO inverters and the
mathematical model of the motor are elaborated in
sec. 2. Section 3, provides an explanation for both
SBI and z-source inverter. The proposed master and
slave controllers for both speed and maximum power
point tracking (MPPT) are detailed in sections 4 and
5 respectively. A comparison with the simulation
results for the proposed inverter and other systems is
conducted in section 6. Real-time emulation of the
developed and selected system is implemented using
OPAL- RT in section 7. Finally, Section 8
summarizes the research and its conclusion.
2. The proposed SPAM-drive control system
The proposed system comprises SPAM with its two
windings, the open energy system (OES), and the
controller (as shown in Figure 1). In the following
Fig. 1 the proposed SPAM- drive fed from an OES
sections, each subsystem will be explained in some
detail.
2.1. Single phase asynchronous motor model
This machine is equipped with two windings: main
and auxiliary. There are four modes of operation as:
split-phase, capacitor starting, capacitor-starting
capacitor-running, and main and auxiliary winding
mode. In this study, a capacitor-starting single-phase
induction motor (SPIM) is used.
2.1.1. The mathematical model of SPIM
The dq-reference frame equations for the electrical
model for both stator and rotor of SPIM are [26]:
(1)
(2)
).
).
(3)
).
).
(4)
Where, (5)
(6)
(7)
(8)
The instantaneous electro-magnetic internal torque of
the motor can be computed as:
(9)
The dynamic equation is:
(10)
Where, are the stator voltage in dq-axis
frame, are the stator resistance in dq-axis
frame. are the stator inductance in dq-
reference frame, p is the differential operator (d/dt),
are the stator currents in dq-frame,
are the mutual inductances in dq-frame, are
the effective turns in dq-frame,
are the rotor
resistance referred to stator in dq-frame,
are
the rotor current referred to stator in dq-frame,
are the rotor inductance referred to stator in
dq-frame, is the rotor angular speed,
are
the leakage inductance of rotor in dq-frame,
are the leakage inductance of stator in dq-frame, is
the motor electrical internal torque, P is the number
of pair pole of the motor, and is the motor inertia.
In the above equations, the auxiliary winding
represents d-axis components and the main winding
represents the q-axis components. So, the supply
voltage equal to as:
(11)
Pulses
Open Energy Source
(OES)
SPAM
The proposed Controller
Vg Ig
w
r
w
r
*
Ias
Vas
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(12)
Where, C is the capacitor connected for starting.
2.2. An Open Energy System (OES)
Figure 2 illustrates the OES. It consists of several
huge nanogrids that are connected to each other
through a DC-link (as shown in Fig. 2a). These
interconnected nanogrids are controlled with a
smart system to manage the flow of power to
each other. Each nanogrid has a power converter
to produce both DC and AC supplies. The class
cal nanogrid uses a two-stage converter-inverter
set. But, the modified nano-grid contains a
SIMO-inverter as shown in the Fig. 2b.
There are two types of SIMO-inverters: switched
boost inverter (SBI) and z-source inverter (ZSI) – as
shown in Fig. 2c. For this study, the PV is selected as
a renewable source used to power all grids. An array
of PV is arranged as number of series and parallel
modules are connected with each other to provide
the required power with the appropriate terminal
voltage. In this case, the SunPower SPR 305WHT
(appendix A) module is used. Also, their Power-
Voltage (P/V) and current- voltage (I/V)-curves are
illustrated in Figure 3 (for 2 in series and 10 in
parallel) to supply about 6 KW.
3. Single input multi-output inverter (SIMOI)
Through the following lines, both the SBI and ZSI
with some detail will be explained. Furthermore, a
comparison between SIMOI and SISOI will
performed. Thus, SISOI will also be brief explained.
An Open Energy System
DC-modified Nanogrid
DC-Loads
AC-Loads
DC-modified Nanogrid
DC-Loads
AC-Loads
DC-modified Nanogrid
DC-Loads
AC-Loads
.
.
.
.
.
.DC-Bus
(a)
DC
Renewable
Resources
Battery
Management
System
Single-Input
Multi-output
Inverter
(SIMO) AC
(b)
Switched Boost
Inverter
(SBI)
Z-Source
Inverter
(ZSI)
DC
DC AC
AC
DCDC
(c)
Fig. 2 open energy system (a) OES with loads (b)
DCMnG (c) SIMO-inverters
3.1. Switched boost inverter (SBI)
As shown in Figure 4, SBI consists of five IGBTs, 2-
diodes, one coil, and one capacitor to transmit the
power from the PV-source to the motor. It depends
on two modes of operation: the shoot-through and
non-shoot through techniques to turn-on and off
switches. This technique protects all switches from
short-circuit current and there is no need to dead-time
delay circuit to avoid overlapping between two
IGBTs on the same inverter leg. Its output can be
controlled directly to upward or downward the DC
and /or AC voltage values. Thus, when it is supplied
from the PV-intermittent source, it increases its AC-
output voltage to sufficient value that produces the
torque required to start-up the motor with a pre-
scribed speed.
In the non-shoot through state, toff = (1-D)×Ts, the
switch S is turned off and the inverter bridge is
represented by a current source. Where, toff is the turn
off time for the switch S, D is the duty ratio, and Ts is
the periodic time for switch S equal (toff + ton) and ton
is the turn-on time. Now, the voltage of the renewable
source (i.e., PV)(), and the energy stored in the
inductor L together will supply the inverter and the
capacitor through diodes Da and Db.
The inductor current in this interval equals the
capacitor charging current added to the inverter input
current. Note that the inductor current is assumed to
be sufficiently high for the continuous conduction of
diodes Da and Db for the entire interval. The inductor
current () will exceed linearly to a value equal to
that of the capacitor charging current added to the DC
load current and the inverter input current (assuming
continuous conduction mode) for the interval ((1-
D)×).
Fig. 3 Characteristics of the PV module (a) IV
curves (b) PV-curves
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The SBI utilizes the shoot-through interval of the H-
bridge to appeal to the boost operation. So, the
traditional PWM control technique of the traditional
voltage source inverter (VSI) should be modified to
incorporate the shoot-through state to be suitable for
the SBI [27].
The PWM scheme for SBI is developed based on the
traditional sine-triangle PWM with voltage switching
level. This technique has been illustrated during
positive and negative half cycles of the sinusoidal
modulation signal (t) and is given in details in
[28]-[30]. However, the DC-output voltage of SBI
can be computed as:
(12)
Where, is the DC-link voltage of the inverter.
It should be noted that the shoot-through state of the
inverter bridge will not affect the harmonic spectrum
of the inverter’s output voltage if the sum of shoot-
through duty ratio (D) and the modulation index (M)
is less than or equal to unity.
(13)
Hence, the values of M and D are chosen according
to the peak value of the AC output voltage AC that is
given by:
= M.VDC = M.
. (14)
3.2. Z-Source inverter
As shown in Figure 5, it contains more passive
elements than SBI. It implies two identical coils and
capacitors – for symmetrical one – to prevent short-
circuit current when the switches are conducting and
4- IGBTs as a classical inverter and one diode to
block reverse current. There are three modes of
operation for z-source inverter: the active state, zero
state, shoot-through zero state. Table 1 describes
these operating states.
The voltage across each capacitor is equal and the
current through each coil is also equal. So, in shoot-
through state, , if the duty ratio is equal to
(
, where is the total shoot-through time
through one cycle and T is the periodic time, then,
applying Kirchhoff’s Lows:
(15)
(16)
The state-space equation for the Z-inverter can be
written as follows:
(17)
The steady state parameters can be obtained by
setting equation (17) to zero:
(18)
According to the equation (18), the AC- peak output
voltage of the inverter can be determined as:
.
(19)
Where, is the peak value of the modulation wave
(i.e., sine wave), is the peak value of the carrier
wave (i.e., triangular wave), is the modulation
index of the inverter, is the dc-link voltage of the
inverter,
For more details about two-level z-source inverter, it
can be referred to [31]-[34]
3.3. The sinusoidal PWM-SISOI
The sinusoidal-PWM (SPWM) inverter is
considered as a single-input single-output inverter
(SISOI) which has only one DC-input voltage and
only one AC-output voltage. It can be supplied
directly from the DC-source such as PV or battery
bank as shown in Figure 6.
4. The master speed control and MPPT
algorithm
The block diagram for the master speed controller is
shown in figure (7). The controller strategy depends
on the variation of both voltage and frequency with
the same rate – as a scalar value – to keep the motor
internal torque constant. The reference frequency and
voltage can be computed according to the following
equations:.
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Da
Db
S1 S3
S4 S6
S
L
C
GS GS1
GS4
GS3
GS2
Lf
Lf
Cf
Cf
Vc
Vc
ic
iLVi
Low pass Filter
Aux.
Main
Rotor
SPAM
Cst
V
g
Fig. 4 SPAM fed from PV-array via a SBI
S1 S3
S4
GS1
GS4
GS3
GS2
Lf
Lf
Cf
Cf
i
Low pass Filter
Aux.
Main
Rotor
SPAM
L2
L1
C1C2
Cst
S2
V
g
Vdc
1L
i
2L
i
1C
V
2C
V
AC
V
Z
i
Fig. 5 SPAM fed from PV-array via a ZSI
Table 1. Switching modes of z-source inverter operation
Switching States (Modes)
Output voltage
Active state
1
0
0
1
Finite Voltage
0
1
1
0
Zero state
1
0
1
0
Zero
0
1
0
1
Shoot-through state
1
1
Zero
1
1
1
1
1
1
S1 S3
S4
GS1
GS4
GS3
GS2
Lf
Lf
Cf
Cf
Low pass Filter
Aux.
Main
Rotor
SPAM
Cst
S2
Fig. 6 SPAM fed from PV-array via a SISO inverter
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P/60 KI
Speed Ramp
Nr
*fr
*
Kp
P/60
1st Order LPF
Nr
Integ. Limiter
-
++
+
Slip Comp.
Limiter
+
+
fr
fslip
Kvf
Voltage Limiter
Frequency Limiter
V
s
*
f
s
*
Fig.7 The master controller (sequence of scalar speed control V/f block diagram)
Read
gg IV ,
Compute:
)()()( kIkVkP ggg
)1()1()1( kIkVkP ggg
Compute:
)1()()( kPkPkP ggg
)1()()( kVkVkV ggg
If
0)()( kVkP gg
YesNo
ZZZ DkDkD )()1(
ZZZ DkDkD )()1(
Return
)1( kDD ZZ
To Pulse
generation
1
-1
0
Z
D1
1
Z
D
** .rm SinV
(a)
(b)
*
r
f
Zero-order
Hold
360
360
dt
r
w
*
r
Sin
*
m
V
**.rm SinV
(c)
Fig. 8 Slave control: (a) MPPT flow chart (b) modulator-signal generation
(c) modified sine triangle PWM generation
(20)
(21)
Where P is the number of pair-poles, is the
rotor reference and actual frequency and e is the error
signal. The output of the PI-controller is the slip-
frequency:
(22)
Then, the reference synchronous frequency of the
motor can be computed as:
(23)
The reference voltage peak- value
: (24)
Where, is a constant depends on flux and selected
according to the rated frequency and voltage of the
machine. For this work, this value is equal 2.4 for the
test machine. The main purpose of this control is to
generate the modulation signal required to produce
IGBTs gating signals for all inverters.
So, the sinusoidal signal can be computed –
according to the block diagram of Fig. 8-a as:
(25)
Where, is the reference position angle and can be
computed from the reference frequency as:
(26)
This modulated signal is compared with the triangle
signal according the modulation index M as:
(27)
Where, is the peak value of the carrier-triangular
wave – as shown in Fig. 8-b.
This technique is used for speed control for all
compared inverters. But, for SIMOIs, another
parameter is used with the combination of M to
control the voltage of DC-link and this will directly
affect the motor speed and torque. This parameter is
the duty ratio D, this can be controlled according
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P/60 KI
Speed Ramp
Nr
*fr
*
Kp
P/60
1st Order LPF
Nr
Integ. Limiter
-
++
+
Slip Comp.
Limiter
+
+
fr
fslip
Kvf
Voltage Limiter
Frequency Limiter
V
s
*
f
s
*
Fig.7 The master controller (sequence of scalar speed control V/f block diagram)
Read
gg IV ,
Compute:
)()()( kIkVkP ggg
)1()1()1( kIkVkP ggg
Compute:
)1()()( kPkPkP ggg
)1()()( kVkVkV ggg
If
0)()( kVkP gg
YesNo
ZZZ DkDkD )()1(
ZZZ DkDkD )()1(
Return
)1( kDD ZZ
To Pulse
generation
1
-1
0
Z
D1
1
Z
D
** .rm SinV
(a)
(b)
*
r
f
Zero-order
Hold
360
360
dt
r
w
*
r
Sin
*
m
V
**.rm SinV
(c)
Fig. 8 Slave control: (a) MPPT flow chart (b) modulator-signal generation
(c) modified sine triangle PWM generation
KI
Kp
-
++
+
Voltage limiter
*
dc
V
dc
V
2
dc
V
-
+
g
V
+
-
Compensation
MPPT
Algorithm
g
I
g
V
0
D
+
+
maxst
V
mppt
D
Selection
Algorithm
stv
V
Read
max
,, ststv VVt
Is
Initialization
start
tt
stvst VV
maxstst VV
Terminate
(a)
(b)
+
-
+
-
*
.rm SinV
st
V
)(tV
tri
1
GS
a
S
4
GS
+
-
+
-
*
.rm SinV
st
V
)(tV
tri
b
S
2
GS
3
GS
GS
(C)
st
V
Fig. 9 SBI-Voltage control (a) DC-link voltage control (b) starting algorithm (c) logic gating signals
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Table 2 the main parameters for both Z-source and SBI inverters
SBI parameters [18]
ZSI-parameters [35]
parameter
value
unit
parameter
value
unit
Inductance of main inductor (L)
5
mH
Inductance of main coils (
1
mH
Capacitance of main capacitor
(C)
1500
μF
Capacitance of main capacitors
(
1300
μF
Inductance of filter inductor ()
1
mH
Inductance of filter inductor ()
1
mH
Capacitance of filter capacitor
()
150
uF
Capacitance of filter capacitor
()
150
uF
to the maximum power point tracking (MPPT) for the
PV-array. In this research, the hill-climbing
algorithm is used as a MPPT. The flow chart for this
algorithm is shown in fig. 8-c. The same MPPT
algorithm is used for both z-source and SBI inverters.
In z-source inverter the duty ration is used in
shoot-through period to control the DC-link voltage
as shown in Fig. 8-b. But, in the SBI, a proposed DC-
link voltage controller is used.
5. DC-link voltage controller of SBI
The block diagram of the DC-link voltage of SBI
is depicted in fig. 9-a. This block produces the
voltage level control signal ( that is needed for
shot-through signals controlling the switch (S).The
control algorithm depends on introducing a
mathematical model for the actual value of that
can be computed as follows [18]:
From the strategy and analysis of the SBI,
, , so:
(28)
If by substituting in Eqn. 28,
(29)
By substituting in Eqn. 12 from 29,
(30)
The block diagram for this model is drawn as a
reference according to Eqn. 30. Also, its output is
added to the output of the PI-controllers used for
voltage control loop with compensation - as shown in
Figure 9-a. Two operating modes are offered. The
first one is proposed through starting to keep the
voltage of DC-link constant. This increases the
voltage to its maximum value and the second
algorithm achieves MPPT as shown in Fig. 8-c. The
output control signal of the voltage control is denoted
by . On the other hand, the control signal in case
of MPPT is denoted by .The flow chart of this
algorithm is shown in Fig. 9-b. This algorithm
depends mainly on the starting time . If the time is
less than or equal to the motor start-up time, the
controller maintains the motor voltage constant
through start-up. After this, the operation time
increases to more than start-up time, thus activating
the MPPT algorithm. The digital logic gates required
to generate the 5-control gating signals for the IGBTs
of the SBI is shown in Fig. 9-c. For more details
referred to [17],[18].
6. Simulation Results and Discussion
To test the robustness of the proposed system, a
comparison between the SIMO and SISO inverters is
performed. Two SIMO inverters are tested (i.e., z-
source and SBI). The SISO inverter is the sinusoidal
PWM which is compared to the other two types. The
same motor-speed controller – proposed in Section 4
is used for all types with the same parameters. The
gain parameters for PI-speed controller are:
. The name plate date of the
fractional-horse power test single-phase induction
motor and its main parameters are included in
appendix B [10]. The PV-array consists of two
modules in series and ten in parallel with irradiance
varies from 200 to 1000 w/m² at 25° C. The
parameters of PI-controller for DC-link voltage
control of SBI is: 0.00001 and
with limiting block values 2. All parameters are
selected according to Ziegler-Nichols Formula. The
main parameters for both z-source and SBI inverters
are presented in Table 2. The switching frequency for
all inverters equal 10 KHz. All systems are
implemented using the Matlab/Simulink software
package (ver. R2018a) [35]. To test the robustness of
the proposed system against the DC-link input
variation for all inverters, several cases are
investigated. The first case is designed using a
constant battery input voltage with a value of 126 V.
The second case, when all inverters are supplied from
a PV-array with a constant irradiance (1000 w/m²)
with a 126V output. The third case, is the study of the
effect of irradiation on the motor performance when
its value is reduced from 1000 to 200 w/m² by starting
the motor. Furthermore, the robustness of the
controller is also tested by starting, accelerating, and
decelerating of the motor. The speed trajectory is
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considered initially as a ramp with acceleration to
increase the motor speed linearly to 1500 rpm across
1 second of start time. Then, the motor reaches to
steady state with a constant speed for another second
and after that the motor decelerates to 750 rpm over
the period (2 to 2.5 seconds). Finally, the motor
reaches a speed of 750 rpm and continues to
operate at this speed as a steady-state value. The test
machine is a single-phase staring-capacitor induction
motor. The starting capacitor is used during start-up
until the motor reaches to 80 % of its nominal speed
(i.e., 1800 rpm).
6.1. Case 1: The motor is powered by a battery
bank through the inverters
In this case, the motor is powered by a battery bank -
with a constant value equal to 126V- through the
aforementioned three inverters. Fig. 10 illustrates the
proposed speed trajectory for motor power across all
inverters. As can be seen, they all showed a good
response with some overshooting compared to the
reference speed trajectory. In addition, it can be noted
that the speed trajectory with SBI is under damping
with minimum overshooting in comparison with the
other two types. Figures 11, 12 and 13 demonstrate
the total stator current, the main and auxiliary
winding currents with all inverters. At 80 % of the
synchronous speed (i.e., 1440 rpm) the capacitor is
cut off and voltage across its terminals is shown in
Fig. 14. The waveform of internal electric torque of
the motor is illustrated as an instantaneous value
given in Fig. 15. At start-up, the motor torque is
increased until the motor reaches steady state and
then decreases to a nominal value.
Figure 10 Case (1) actual and reference forward speed
trajectories for inverters with battery bank
Fig. 11 total stator currents with all inverters
Fig. 12 main-winding stator currents with all inverters
Fig. 13 the auxiliary-winding stator currents with all
inverters
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Fig. 14 starting capacitor voltage with all inverters
Fig. 15 Motor internal electric torque
6.2. Case 2: The motor is powered by a PV-array
without shade
In this case, the motor is delivered by a PV-array
through the selected inverters. In this case the PV-
irradiance is assumed to be constant without shade
and equal to 1000 W/m² - as shown in Figure 16-a.
Figures 16-b and c illustrate the voltage of PV-
terminal and the power profiles of this radiation. As
stated, at the start the voltage value is roughly
constant and equal to 126 V. Then, while starting, its
value is affected by switching the load and inverter.
It therefore varies slightly according to the motor
current and power. The motor speed trajectory is
shown in Fig. 17. Due to oscillations in the PV-output
voltage, the speed trajectory isalso affected
accordingly, especially with the SISO-inverter due to
absence of the first stage (i.e., converter). However,
both two-stage inverters almost follow the refernce
speed trajectory. But, the best drive is that of SBI due
to the robust controller offered. In addition, z-source
inverter is tracking with a slight deflection. Figures
18,19, and 20 demonstrate the stator total, main-
winding and auxiliry currents. As shown, when
starting the current will increase and then decrese in
steady state. Figure 21 illustrates the starting
capacitor voltage for the motor with all inverters. As
shown, when the motor reaches to 80% of the
nominal speed, the capcitor circuit is open. It depends
on the temporal response of each proposed system
based on its controller and the voltage of the DC-link.
Likewise, SBI is much faster than others with
minimum overshot. Accordingly, the internal
electrical torque, shown in Figure 22, is also affected
by the DC-link input voltage of the inverter. The
motor torque gradually increases at start-up and then
decreases with the current steady state. As shown, the
SISO inverter provides low-starting torque comapred
to other two inverter types.
Figure 10 Case (2) actual and reference forward speed
trajectories for inverters with battery bank
Fig. 16 Case (2) PV-array (a) irradiance (b) voltage (c)
power
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Fig. 18 The total stator currents for all inverters
Fig. 19 The main-winding stator currents for all inverters
Fig. 20 The auxiliary-winding stator currents for all inverters
Fig. 21 voltage across the starting capacitor
Fig. 22 Motor internal electrical torque
6.3. Case (3): The motor is powered by a PV-array
with shade
In this case, the shadow for the PV-array shall be
considered. At t-0.5 to 0.6, the insolation is reduced
from 1000 W/m² to 200 W/m² during this period as
shown in Fig. 23a. Accordingly, the terminal voltage
and generated power are shown in Figures 23-b and
c. The reference and actual speed trajectories of all
compared inverter systems are shown in the Fig. 24.
As illustrated, the SBI with the help of the proposed
voltage controller and its strategy, succeeded to
follow the trajectory through start-up. Although the
insolation was reduced to its minimum value, the
DC-link voltage is increased to a sufficient value.
Moreover, the z-source inverter also followed the
trajectory with a time delay and a maximum overshot
at start-up. The SBI and z-source inverters followed
the speed trajectory through the deceleration without
error. However, the SISO-inverter system took more
delay time without deviation of the speed trajectory
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through starting period. Furthermore, it could not
follow the deceleration of speed trajectory. Figures
25, 26, and 27 illustrate the stator current, main and
auxiliary windings respectively. At starting, the
motor with both SBI and z-source inverters consumes
fewer power than the SISO inverter. The capacitor-
starting voltages with all inverters are shown in fig.
28. The capacitor takes less time with the SBI
inverter through starting, then the z-source and SISO
inverters consume more time with a delay before the
capacitor circuit is opened. This can be illustrated
clearly through the internal electrical torque of the
motor as shown in Fig. 29. The motor exerted more
torque for the SBI and z-source inverters but SISO-
inverter produces a bit of torque due to the lake of
input DC-voltage.
Fig. 23 PV- (a) irradiance (b) terminal voltage (c) output
power
Fig. 24 actual and reference forward speed trajectories for
inverters with PV-shadow
Fig. 25 The total stator currents for all inverters
Fig. 26 the main-winding stator currents for all inverters
Fig. 27The auxiliary stator currents for all inverters
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Fig. 28 starting capacitor voltages for all inverters
Fig. 29 Motor electric internal torques with all inverters
7. Real Time Implementation for the SIMO-
Inverter Systems
In power systems and drives, real time
simulator (RTS) is used to design, test control, and
protect equipment performance before installation on
actual state. So, in this work, the combination of
OP4510 real-time hardware-in the loop (HIL) and
rapid-control prototype (RCP) [36] and OP8660 HIL-
controller and data acquisition interface [37]
platforms are used to implement the proposed drive.
According to simulation results, the SPIM-drive
based on SBI will be only implemented to overcome
the parameter variations of the PV-fluctuations. The
overall practical system is shown in figure 30. All
output parameters of the drive such as speed, torque,
capacitor voltage, and currents are measured as real
signals through the analog port of the HIL and its
controller. The speed trajectory is scaled down
through the Simulink platform by 1000. So, as shown
in fig. 31-Chs. B and C, the actual and reference
speed trajectories are nearly identical with real scale
1000 rpm/ div. In addition, the electrical internal
torque is scaled down by 20 and channel scale is
500mv/div, so as shown in fig. 31-Ch. A, the real-
scale value is 5 N.m. /div. The total stator current,
main, and auxiliary winding currents are also the real
scale is 10 A/div. As illustrated in fig. 32 Chs. A, B,
and C, at starting the motor currents are increased and
then decreased after steady-state. This can be clearly
depicted as shown in fig. 33. The starting capacitor
voltage ensures the starting process as illustrated
through Ch. D with real-scale 200V/div.
8. Conclusion
This article has examined the performance and
behavior of a single phase induction motor when fed
from an intermittent voltage source, such as a solar
cell via SIMO SBI and z-inverters. This manuscript
suggested a scalar voltage/frequency as the master
controller for the motor speed. In addition, another
slave controller was proposed for DC-link voltage
control and MPPT algorithm. This controller
contributed to keep the DC-link voltage of the SBI
constant to a certain value when the PV-array has a
low radiation due to shade or cloudy weather. This
value is sufficient to ensure the torque and current of
the motor leads to better performance during starting
and running. SIMO inverters are the best solution to
ensure the best performance for SPIM drives with
these intermittent sources compared to the SISO
inverters. The proposed system was implemented in
a real time. Thus, in the near future, it can be easily
deployed as a true physical prototype.
Appendix A
PV-Module Specifications
= 305W, = 208.6W, P (= 5.58A, V
(= 54.7V, = 5.96A, =64.2V, =96,
=600V
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Essamudin A. Ebrahim, Emad A. Sweelem
E-ISSN: 2224-350X
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Volume 17, 2022
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