AN2946 datasheet(16/38 Pages) STMICROELECTRONICS

Part #	AN2946

Description	Solar-LED streetlight controller with 25 W LED lamp driver

PDF	38 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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16 / 38 page

Hardware design

AN2946

16/38

Doc ID 15473 Rev 2

Figure 15.

Charging current versus solar module output voltage

The charging current is measured against different output voltages of the solar module. A

DC source is used to simulate the solar module output and when its voltage changes from

13.1 V to 19.1 V, the charging current is limited to around 0.5 A. This demonstrates the

proper operation of the first stage.

●

Stage 2:

In stage 2, when 11 V

< V

BATTERY < 14.3 V, MPPT is implemented. To simulate the V-I curve

of the solar module, the test method is proposed as shown in Figure 16 with two important

equations below.

Equation 1

Equation 2

Figure 16.

MPPT test diagram

The V-I curves of this test system and charger power are shown in Figure 17.

Usc

Udc

R Isc

⋅

–

Psc

Usc Isc

Udc

R Isc

⋅

–

() Isc

⋅

AN2946 Datasheet(PDF) 16 Page - STMicroelectronics