Page 109 - 2024-Vol20-Issue2

105 | Maddu & Bhasme

becoming the usual method for operating inverter switches the IM are shown in Table I. The specifications of the Wavect
to achieve the needed output voltage [6, 7]. PWM techniques real-time controller are shown in Table II.
have attracted the attention of the research community in the
field of AC motor control applications. The different PWM TABLE I.
topologies are developed for high-power and medium-voltage THREE-PHASE INDUCTION MOTOR
motor drives [8]. The major factors such as power level, ma-
chine type, and the power semiconductor devices decide the S.No. Squirrel cage type
economic design of the power converter in AC drive systems
concerning performance and cost [9, 10]. Among different 1 Parameter Value Units
PWM methods, SPWM and SVPWM for a two-level VSI are 2
popularized in motor applications. These PWM techniques 3 Stator Resistance, Rs 0.81 ?
are utilized in vector-controlled AC motor drives to forecast 4
the inverter switching instants from the modulating signals at 5 Rotor Resistance, Rr 0.49 ?
the control output. In the SPWM method, a high-frequency mH
carrier wave is compared to the modulating reference wave, Stator Inductance, Ls 264 mH
then the intersection points decide the inverter switching in- mH
stants. As in the SVPWM, the net reference voltage space Rotor Inductance, Lr 372
vector can be divided into the sectors and then calculated by
the switching times [11]. The SVPWM technique is very pop- Magnetizing Inductance, Lm 0.1177
ular in Sensor and Sensorless vector control applications due
to its high output power for the high-speed operation of the II. SYSTEM DESIGN
motor. It achieves higher DC bus utilization, low distortion
in current waveform, and extended speed range of AC motor. A. Two level VSI
The SPWM method is restricted for low-speed applications Inverters are the power converters at convert DC supply volt-
due to its higher THD compared to the SVPWM method [12]. age into AC voltage. The purpose of an inverter is to ma-
However, the hardware implementation of the PWM tech- nipulate the amplitude and frequency of the sine wave. In
niques is very complex with limited accuracy. To address the general, Three-phase, two-level voltage source inverters are
aforementioned problems, simple and low-cost FPGA-based widely used in medium-voltage and high-power drive applica-
real-time digital controllers are preferred in vector-controlled tions [17]. Each leg of the inverter is of having two switches
AC motor drives [13]. A powerful FPGA platform is preferred and a total of six switches. If the output of a switch is con-
in the digital domain to obtain high-performance power elec- nected to the upper input terminal +V dc/2 is positive other-
tronics. Earlier traditional microcontrollers or digital signal wise, it is negative (lower terminal-V dc/2 ). The output, vao
processing (DSP) relied on C/C++ programming languages or, pole voltage thus oscillates between(+V dc/2 to -V dc/2)
whereas FPGA depended upon hardware description language ; The Sinusoidal modulating signals can be written in terms
(HDL). During the design process, extensive verification is of the peak magnitude M,
highly required to optimize the required hardware design [14].
Using FPGA, the computation load can be highly reduced vleg,a = Vdc · da = Vdc M Sin(2p f t) + Vdc (1)
along with reduced power transistor switching losses. More- 2 2
over, the microprocessor or DSP needs a higher computation
time compared to FPGA applications in machine model tech- vleg ,b = Vdc · db = Vdc M Sin(2p f t - 2p /3) + Vdc (2)
niques of AC drives [15]. The complex SVPWM algorithms 2 2
implemented using FPGA prove better results due to their
high computational speed and inherent capability. However, vleg,c = Vdc · dc = Vdc M Sin(2p f t + 2p /3) + Vdc (3)
in practice, the importance of advanced power electronics ma- 2 2 (4)
terials like Silicon Carbide (SiC) and Gallium Nitride (GaN) (5)
is rapidly increasing for power density requirement applica- The duty cycles are computed as follows:
tions with FPGA. It enables motor controller capabilities to
achieve a higher control bandwidth [16]. In this work, an di = mi + 1 where i = a, b, c
FPGA-based Wavect real-time controller has been adopted 2 2
due to its simplicity in hardware implementation, accuracy,
fast response, and low-cost controller. Also, the parameters of The fundamental leg voltages will be,

vleg,a = Vdc · da = Vdc M Sin(2p f t) + Vdc
2 2

vleg,b = Vdc · db = Vdc M Sin(2p f t - 2p /3) + Vdc (6)
2 2