Pure sine wave VS modified sine wave inverter battery consumption

Thread Starter

Joeadeoye

Joined Apr 2, 2017
14
Hello fellow engineers, I have made two inverters, one is a Pure Sine Wave, which I made using EGS002 chip using Full bridge topology. The second is a modified sine wave inverter which I made using IC4017 darlington counter, using a push-pull topology.

I powered the pure sine wave inverter, connecting a 500Watt load, I measure the input Ampare using a clamp multimeter, it was consuming approximately 40 amps from the battery.

I connected the same 500watt load to the modified sine wave, and it consumes approximately 20 amps from the battery.

Both inverter runs on 12v 200AH battery. I want to know why the pure sine wave consumes more power compared to the modified sine wave.

Thanks.
 

Alec_t

Joined Sep 17, 2013
11,738
1) A 'modified sine wave' is in reality a modified square wave, with a dead time between polarity reversals.
2) Your clamp meter is likely calibrated to read RMS currents for true sine wave inputs. Accordingly its response to non-sinusoidal inputs won't be accurate.
 

Thread Starter

Joeadeoye

Joined Apr 2, 2017
14
1) A 'modified sine wave' is in reality a modified square wave, with a dead time between polarity reversals.
2) Your clamp meter is likely calibrated to read RMS currents for true sine wave inputs. Accordingly its response to non-sinusoidal inputs won't be accurate.
Thanks for the response. I also observed this manually, while using the sine wave, the battery terminal gets warm after 5 minutes of work, but for the modified square wave, it doesn't get warm, meaning, the sine wave is sucking more energy outta the battery.
 

BobTPH

Joined Jun 5, 2013
2,579
How is the sine wave inverter done? If linear, then it would use more power. It switching (PWM), it should use about the same.

Bob
 

crutschow

Joined Mar 14, 2008
25,640
Are any components, such as the bridge transistors, getting warm in the the sinewave converter?
If the sinewave converter takes more current, then the most likely reason is that the transistors are not being switched properly.
Are they the same size transistors as in the modified sinewave converter?
 

Thread Starter

Joeadeoye

Joined Apr 2, 2017
14
Are any components, such as the bridge transistors, getting warm in the the sinewave converter?
If the sinewave converter takes more current, then the most likely reason is that the transistors are not being switched properly.
Are they the same size transistors as in the modified sinewave converter?
Both mosfet and transformer for both inverters are the same rating. The mosfets only get warm after long working time, like 30mins of operation, in both sine and modified sine inverter.
 

crutschow

Joined Mar 14, 2008
25,640
Both mosfet and transformer for both inverters are the same rating. The mosfets only get warm after long working time, like 30mins of operation, in both sine and modified sine inverter.
Well, something in the sinewave inverter must be getting quite warm if it's dissipating an extra 240W.

Are you sure the output voltage is the same for both inverters into the same load?
Does the load get to the same temperature with both inverters?
Do you have a true RMS meter to measure the output voltage?
 

MrAl

Joined Jun 17, 2014
7,849
Hello fellow engineers, I have made two inverters, one is a Pure Sine Wave, which I made using EGS002 chip using Full bridge topology. The second is a modified sine wave inverter which I made using IC4017 darlington counter, using a push-pull topology.

I powered the pure sine wave inverter, connecting a 500Watt load, I measure the input Ampare using a clamp multimeter, it was consuming approximately 40 amps from the battery.

I connected the same 500watt load to the modified sine wave, and it consumes approximately 20 amps from the battery.

Both inverter runs on 12v 200AH battery. I want to know why the pure sine wave consumes more power compared to the modified sine wave.

Thanks.
Hi,

Measure the load current. That will tell you if they are both powering the load the same way.

Back some 35 years ago we designed and built synthesized sine wave converters with less than 1 percent distortion and around 90 percent efficiency. These things put out a very nearly perfect sine wave. If the design is not right however it will not achieve 90 percent efficiency but could be much less. You may have to check the design too as you said you built it yourself.
 
Top