microinverter marketing pres

250 W Grid Connected
Microinverter
Enabling new generation of PV systems
250 W microinverter for PV applications
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• Key features:
• 250 W power capability
• Output voltage Vout= 230Vac 50Hz -240Vac 60Hz
• High conversion efficiency (>94%, 93.5% CEC)
• MPPT efficiency (99%)
• Decoupled control of active and reactive power
• Overcurrent and anti-islanding protection
• Galvanic isolation between the panel and the grid
• Key products:
• STM32F103ZE (32-bit microcontroller)
• STB18N65M5, STH180N10F3-2 (power MOSFETs)
• PM8834, L6390 (MOSFET drivers)
System evaluation board order code:
STEVAL-ISV003V1(*)
• STPSC606, STPS1545C, STTH12R06 (diodes)
• SMBJ (EOS surge protection)
• ST3232EB (RS-232 interface)
(*) Available at the end of Q1 2012
250 W microinverter: block diagram
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250 W microinverter: DC-DC section
Electrical Specs
• Vin= 18V to 55V
• Pout= 250W
• Vmppt= 20V to 40V
• fsw = 35kHz
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The topology
Vin
L1
+
• Iin=7,6A (nominal)
STTH12R06
Vout
+
• Vout= 370Vdc to 430Vdc
• Iout= 0.65A (nominal)
Max Efficiency
DC-DC converter 97.4%
STH180N10F3-2
PM8834
MOSFETs
driver
L2
HF
transformer
STTH12R06
STH180N10F3-2
32-bit MCU
STM32F
ISOLATED INTERLEAVED BOOST
CONVERTER
250 W microinverter: DC-AC section
Electrical Specs
The topology
• Vin= 370Vdc to 430Vdc • fsw1= 17kHz (high frequency leg)
STPS1545C
• fsw2= 50Hz (low frequency leg)
•Vin (nominal) = 380 V
STPSC606
STB18N65M5
STB18N65M5
• Vout= 230Vac / 240Vac
• fout= 50Hz / 60Hz
L6390 + PM8834
• Iout = 1.1 A/ 1.06A
[
E
f
f
i
c
%
i
e
n
c
y
+
Vin
Max conversion efficiency
94.1%
L6390 + PM8834
Vout
MOSFETs
drivers
MOSFETs
drivers
~
Microinverter Efficiency
STPS1545C
]
96
94
92
90
88
86
84
82
STPSC606
STB18N65M5
STB18N65M5
32-bit MCU
0
50
100
150
200
250
300
STM32F
Output Power [W]
HIGH FREQUENCY
LEG
MIXED FREQUENCY INVERTER
LOW FREQUENCY
LEG
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250 W microinverter: MPPT algorithm
The MPPT “Perturb and Observe” algorithm
STM32F and MPPT
DC
Sense V(k), I(k)
DC: Duty cycle value
C: Duty cycle step value
V(k): input voltage
P(k): Power
k4
DC
Vsense
STM32F
Microcontroller
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P(k)=V(k)*I(k)
MPPT
k3
k2
Isense
NO
A/D
converter
YES
k1
Duty cycle
calculation
NO
Previous Power and Input
voltage value register
P(k)>P(k-1)
V(k)>V(k-1) YES
NO
V(k)<V(k-1)
k0
YES
MPPT
controller
DC=DC-C
DC=DC+C
DC=DC-C
DC=DC+C
MPPT is reached following
PV panel curve
250 W microinverter: grid connection
The PARK transformation
q
β
The DQ-Phase Locked Loop (PLL) structure
Vd is controlled to zero with a PI regulator→ GRID ANGLE θe KNOWN
STM32F
Vgrid
Microcontroller
d
θe
α
FROM
Vα and Vβ
(grid voltage and 90°phase shifted voltage
on stationary frame)
TO
Vd and Vq
(two voltage components
on rotating DQ reference frame)
ADVANTAGES of DQ-PLL
• Vd, Vq, Id, Iq are constants in DQ reference frame:
standard PI regulators for their control ensure zero steady state error
• Decoupled control of active P and reactive Q power
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250 W microinverter: smart communication
Communication
section
Power Line Communication
AC bus
Microinverter
ST75xx: STarGRID power line networking SoC
the most integrated and flexible solution for smart
grid applications and smart metering
Wireless Communication
Local
monitoring &
control
Remote
monitoring &
control
•STM32W RF MCUs (ZigBee®)
•SPZB32W ZigBee® modules
•Bluetooth® modules
Data
concentrator
To the AC Grid
Enabling onsite or remote
monitoring of PV system
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