VENDORVIEWPOINT
Whatever the topology, inverters require accurate measurements,
provided by isolated current and voltage transducers, which provide
protection and help to maintain efficiency within the system
less design. Whilst transformer-based inverters as the currents which need to be measured are
provide inherent protection against DC supplies very low, this stage requires a transducer which is
entering the mains grid, transformer-less designs designed specifically for the accurate
are electrically more efficient, despite requiring measurement of milliamps of current. Some of
additional protection circuitry. these transducers also integrate primary jumpers,
Issue I 2010
as well as an additional jumper for test.
Accuracy regardless
Whatever the topology, inverters require accurate Special control is required at the output of the
measurements, provided by isolated current and inverter, in order to provide synchronisation with
voltage transducers, which provide protection and the grid. The inverter must shape the sinusoidal AC
help to maintain efficiency within the system. current so that harmonics are minimised and react
Transducers are used at several points to measure quickly to changes in the grid-side current. The
-pv-management.com the current within PV installations, and each stage transducers used here must provide very fast
has very specific parameters for transducer response times combined with low offset drift.
.solar
performance. Minimising offset drift due to changes in
www
temperature also helps to minimise the need for
At the DC input of the inverter, for example, a complex compensation algorithms.
34
transducer is used to monitor and control the
MPPT, ensuring that it offers the optimal electrical Close collaboration between transducer
load to the PV cell, maximizing efficiency. Here, the manufacturers, such as LEM, and PV inverter
expected rate of current variations is relatively manufacturers will provide the basis for developing
slow, allowing the use of a low-cost open-loop technologies which, together, can deliver real
transducer. Another transducer is used to monitor competitive advantage and market share within the
potentially dangerous leakage currents to ground; growing solar sector.
Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61