# Solar Powered Induction Motor Drive Design

#### Zarzis Rony

Joined Apr 19, 2017
5
Hi guys,
I am designing a solar array fed induction motor pumping system. I will use 100 watt PV panel to run a 0.5hp induction motor pump.The DC link voltage (around 18 -24 volt) will be modulated to AC using a pure sine wave inverter with Space vector modulation. The AC voltage waveform will be less than 20 volt and will be stepped up by a transformer. V/f control will be used for induction motor. Most of the time a DC-DC boost converter is used to extarct maximum power point ,then a inverter is used. So there is no need for transformers for those double power stage systems. But my system will be a single stage system with a inverter and a transformer (no DC-DC converter). Now i have some question on some points:
1. Can i directly use a transformer to step up the voltage from inverter, I mean is there any possibility of destruction of the inverter due to voltage spike?If any then why?
2. Do i need to use any kind of passive filter after inverter to smooth voltage waveform,then fed it to transformer? If yes,then what type of passive filter can be used?
3.Do i need any snubber ? Actually when i am trying to simulate the system in matlab, it suggest me to add a snubber between inverter and transformer and also between transformer and induction motor?pump.

#### Sensacell

Joined Jun 19, 2012
2,595
The first thing that pops out is the inherent problem:

1 Horse Power = 745 Watts

1/2 HP is 372.5 Watts.

Not even considering the conversion losses that make it all much worse.

No way a 100 W solar panel will run a 1/2 HP motor.

#### oz93666

Joined Sep 7, 2010
737
sencell is right ...at least about 600w of panel ...

But your whole plan is wrong ..... Millions of farmers are running pumps from panels around the world , and they don't use AC motors. Without batteries the pump will stop when panels are not delivering 50% output , which will be for most of the day...

Pumps run by brushless DC motors are used .. these not only are more efficient than AC , but they are designed to plug straight into the panels and still deliver some water at low voltage , so when there's clouds around there's still some water being pumped , no storage batteries needed ...

This one runs between 18v-45v has a maximum consumption of 384W and needs 600W of panels

#### Zarzis Rony

Joined Apr 19, 2017
5
The first thing that pops out is the inherent problem:

1 Horse Power = 745 Watts

1/2 HP is 372.5 Watts.

Not even considering the conversion losses that make it all much worse.

No way a 100 W solar panel will run a 1/2 HP motor.
Okay . The thing is i am using an inverter and with that inverter i will control the speed of the IM motor. So with flow control less power will be supplied to motor (than its rating). As solar panel is expensive and household application do not need a high demand 100 W panel will be chosen. Water will be pumped throughout whole sunny day with controlling the flow speed according to insolation level.

#### Zarzis Rony

Joined Apr 19, 2017
5
sencell is right ...at least about 600w of panel ...

But your whole plan is wrong ..... Millions of farmers are running pumps from panels around the world , and they don't use AC motors. Without batteries the pump will stop when panels are not delivering 50% output , which will be for most of the day...

Pumps run by brushless DC motors are used .. these not only are more efficient than AC , but they are designed to plug straight into the panels and still deliver some water at low voltage , so when there's clouds around there's still some water being pumped , no storage batteries needed ...

This one runs between 18v-45v has a maximum consumption of 384W and needs 600W of panels

As far as I know BLDC needs also drive like induction motor. Moreover induction motor is very robust and light and maintenance free

Joined Feb 20, 2016
3,602
BLDC motor is better as has been pointed out above.
There will be losses in the inverter, transformer and the induction motor.
A good BLDC motor will be a lot more efficient.
But 100W panel is WAY too small!
Solar powered BLDC pumps are readily available, often used to run garden fountains and water features for example.
As far as I know BLDC needs also drive like induction motor. Moreover induction motor is very robust and light and maintenance free
BLDC motors are just as maintenance free as induction motors. And I would thing they are actually lighter than a similar powered induction motor.
Total cost to use the system you are talking about will be a lot higher too.

#### shortbus

Joined Sep 30, 2009
7,902
Okay . The thing is i am using an inverter and with that inverter i will control the speed of the IM motor.
You had better do some more reading on induction motors. They don't work like that. At least not single phase motors.

#### Zarzis Rony

Joined Apr 19, 2017
5
BLDC motor is better as has been pointed out above.
There will be losses in the inverter, transformer and the induction motor.
A good BLDC motor will be a lot more efficient.
But 100W panel is WAY too small!
Solar powered BLDC pumps are readily available, often used to run garden fountains and water features for example.

BLDC motors are just as maintenance free as induction motors. And I would thing they are actually lighter than a similar powered induction motor.
Total cost to use the system you are talking about will be a lot higher too.

BLDC motor is better as has been pointed out above.
There will be losses in the inverter, transformer and the induction motor.
A good BLDC motor will be a lot more efficient.
But 100W panel is WAY too small!
Solar powered BLDC pumps are readily available, often used to run garden fountains and water features for example.

BLDC motors are just as maintenance free as induction motors. And I would thing they are actually lighter than a similar powered induction motor.
Total cost to use the system you are talking about will be a lot higher too.

Thank you for your nice advice. Same rated bldc motor is more costly than induction motor + they use heavy rotor magnet then shorted cage in an induction motor. You are right that if I use bldc then overall cost+ efficiency will increase. But my research topic is to integrate an induction motor rated higher than other system components with space vector modulation with lower total harmonic distortion (without using any DC-DC stage). Maybe I will use 1/4 hp three-phase pump with a 100w soalr panel. My inquiry is about: if I add a transformer would it create voltage spike in inverter switch and blow it up? and do I need to use any passive filter?

#### Zarzis Rony

Joined Apr 19, 2017
5
You had better do some more reading on induction motors. They don't work like that. At least not single phase motors.
Shortbus I have read quite a number of research papers on scalar and vector control of induction motor , have completed one undergraduate course in the induction motor, done several simulations on Simulink on IM drive, but I know I have known a little till now. Mr.Nikola Tesla was a genius indeed. I know single phase split capacitor IM is not suitable for variable frequency drive though many great scholars tried to implement two-phase induction motor drive by rewinding single phase(removing the capacitor). I will surely use a three-phase induction motor. Cheers!

#### shortbus

Joined Sep 30, 2009
7,902
I will surely use a three-phase induction motor. Cheers!
We get many people here wanting to modulate single phase motors, that is why I mentioned it. But you seem to know what your doing.