Rev 1.39 03.10.17
Firmware Version 143 ff.
Dingo 4040P Reference Manual
27
In the fast switching mode, the Dingo uses
pulse width modulation (PWM) at 58Hz. It is
recommended that PWM control be used unless
there is good reason not to, as it provides a
smoother control and faster charging.
PWM may generate some audio or radio
frequency interference. If you experience noise on
electronic equipment (for example AM radio), you
could try selecting SET/MODE/PWM = 0 (slow
switching only, option available when PROG=4). If
this does not fix the problem, it’s unlikely that the
noise is generated by the Dingo.
The radio frequency interference from the Dingo
has been tested in PWM mode and found to be
very low. It is at least 15dB below the domestic limit
for European CE, American FCC and Australian
EMI compliance standards.
NOTE: More care must be taken at higher system
voltages (particularly 48V) because the inductance
of the wiring to the photovoltaic panels can
primary battery, and can minimise the amount of
switching required by the relay (which switches over
each time the primary battery bank voltage falls
below FLTV - HYST). The maximum relay switching
rate is one cycle per 30 seconds. A pair of DC
output solid state relays is a good choice here.
This setup may not be the best use of available
charge current. Consider if it would be better to
increase the size of the primary battery bank.
7.5.5 PWM and Slow Switching
When the Dingo is trying to keep the battery
voltage constant, it does this by turning the
charge current on or off as required. It can do
this quickly or slowly.
PWM (fast switching):
SET/MODE/PWM: [PROG= 4 Only]
Selection
Function
0
No PWM used
1
PWM on SOL terminal only
2
PWM on LOAD terminal only
3
PWM on both
cause some ‘ringing’ on turn-off. Keep wiring as
short as possible and panel cable pairs together
(cable tie). On long wiring runs at higher voltages,
some damping may be necessary and possibly
some external clamping of transients. With highly
inductive wiring, the transients may be large
enough to damage the FET switch. Consult the
factory if further information is required.
LOAD terminal PWM switching:
For PWM control to be available on the LOAD
terminal, LSET must be set for Function 10
(Shunt Control).
DO NOT set LSET to Function 11 (Inverted
Shunt Control) if using PWM on load
terminal—see the LSET table.
PWM should only be enabled on the LOAD
terminal (PWM = 2 or 3) if the LOAD terminal
is being used to directly switch a dump load (no
relay).
An exception to this is when the LOAD terminal
is driving a solid state ‘electronic’ relay (non-
mechanical), as these can usually switch at the
PWM speed (58 Hz).
NOTE: PWM is not available on the G relay.
Slow Switching (non PWM):
In slow switching (non PWM) mode, the Dingo
controls the battery voltage by slowly switching
the charge current on and off. It turns the
charge current
OFF
at the voltage set point for
the relevant charge state, and turns the charge
current back
ON
at a slightly lower voltage.
The gap between these two voltages is called
hysteresis and is adjustable (HYST). The larger
the hysteresis value, the slower the rate of
switching on and off.
HINT: Increase the Hysteresis value if using shunt
control with a mechanical relay so the relay
switches less often.
In the slow switching mode, the regulator limits
the
maximum
switching speed to 0.25 seconds
between changes. This virtually eliminates any
audio or radio frequency interference.
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