Charging Principle in Sine wave Inverters

[DIGITRONIC]

Which charging technology is used ,in sine wave inverters or home UPS, by leading companies?

Thanks

 

[tpetar]

I usually saw that LM317 voltage regulator is used to provide float voltage and to limit charging current for battery.


Best regards,
Peter

 

[DIGITRONIC]

I know LM317 is used as charging regulator,but my question is about the inverters in which H-bridge has been used in output section.

Thanks

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I know LM317 is used as charging regulator,but my question is about the inverters in which H-bridge has been used in output section.

Thanks

 

[FvM]

but my question is about the inverters in which H-bridge has been used in output section

Are you talking about battery charging or something else?

 

[DIGITRONIC]

I am talking about charging 120Ah or 150Ah battery.

 

[tpetar]

First post in thread :

Which charging technology is used ,in sine wave inverters or home UPS, by leading companies?

Thanks

I am talking about charging 120Ah or 150Ah battery.

Where you saw 120Ah-150Ah in "home UPS made by leading companies" :shock: ?

Home commercial UPS have small deep cycle batteries 12V 7Ah-9Ah, one battery for 12V, two for 24V system, and three for 36V system.

To achieve higher power of inverter/ups system, voltage is increased. This ensures higher power with tolerable current.

 

[pnjbtr]

I am talking about charging 120Ah or 150Ah battery.

In sine wave inverters charging technique is called boost pfc.
In h-bridge configuration during battery charge we shorted lower mosfet with 7 khz pwm signal.
And due to leakage inductance of transformer in 7v winding we can get 13.8v.

 

[DIGITRONIC]

Thanks for your feedback,you have correctly understood my problem .
Most of the brand uses PIC16F72 to control current and volt.How it works?

Thanks

 

[pnjbtr]

Most of the brand uses PIC16F72 to control current and volt.How it works?

When mains restore,inverter resume battery charging.
Charging current almost sensed through negative wire of battery (from negative track on pcb).
And dropped voltage in negative track fed to op-amp LM324 etc.
LM 324 also amplify these volts for charging current control (adc) pin of PIC16F72.
A user can control charging current with trim pot.
In sine wave inverters (h-bridge type) during battery charge upper mosfet are in sleep mode (have no signal on gates).
And lower side fets are switched with 7 to 20 khz pwm signal.
7Khz with PIC16F72 ,73 and 20 khz with dspic.
Charging current is constant (regulated) till 13.5 to 13.8v of battery.
At 13.8 to 14 v charging current decreased gradually till 0.5 amp.
This technique is also famous in battery charging as CC/CV.

 

[DIGITRONIC]

Thanks pnjbtr. I have seen practically that a 13.5v/10A transformer (input 220v/50hz) charges a battery much faster than a digital charger(7Khz/13.5v).

What is the reason behind this?

Thanks

 

[pnjbtr]

I have seen practically that a 13.5v/10A transformer (input 220v/50hz) charges a battery much faster than a digital charger(7Khz/13.5v).What is the reason behind this?

For battery charging, first we need to see directions from manufacturers brochure.
Generally we can fix 1/10 charging current of total capacity in lead acid batteries (10 amp for 100 Ah).
For VRLA dry batteries, i see in specification we can apply 1/3 charging current (33 amp for 100 Ah).
Regarding normal 13.5v 10 amp charger may harmful for battery plates.
For intelligent battery charger technique,i think CC/CV is best.
Now for CC/CV It depend upon the coder,s hard work in firmware.
I see in luminous LB series (square wave) inverter very good CC/CV charging algorithm.
It charges battery very fast.

 

[Tahmid]

Which charging technology is used ,in sine wave inverters or home UPS, by leading companies?

Thanks

In the step-up portion of the inverter, a full-bridge is used. The microcontroller provides the SPWM to drive the full-bridge which then drives the transformer that steps up the voltage. You have transformers rated at, for example, 7V primary and 250V secondary. This does the step up job.

However, when you connect the mains to the 250V side, the voltage output will be too low to charge the battery. Then, the full-bridge MOSFETs, along with the transformer, are used to form a boost converter. The two low-side MOSFETs are PWM-ed together. The transformer winding provides the inductance to store energy. The two-high side MOSFETs are kept off and only their body-diodes are made use of. In the boost mode (charging mode), the function of the two high-side MOSFETs is only to act as diodes.

The duty cycle of the PWM-ed signal affects the output voltage. The voltage is boosted up enough to charge the battery. The voltage is altered to affect the charging current. The microcontroller monitors and controls the charging voltage and current.

Hope this helps.
Tahmid.

 

[naseerak]

Can some one draw a sequential explanation of this boost PFC technique with schematic/graphic example.