Johnson Controls YORK HYP1100A, Operation Manual, Page: 9 / 24

JOHNSON CONTROLS
9
SECTION 1 - GENERAL INFORMATION
FORM 160.00-O10
ISSUE DATE: 8/24/2020
1
The AC to DC rectifier uses several power devices.
Each phase power assembly contains several power
modules arranged in a parallel connection. Each recti-
fier module contains 2 power devices that are called
the Upper, and Lower device. These 2 power devices
perform the function of rectification from AC to DC
and boost the bus voltage. The power modules used in
the rectifier are also used to provide the harmonic cur-
rent filtering. See Figure 5 on page 13 .
The 6 DC bus capacitors store energy to be used by
the inverter. The rectifier supplies energy into the bus
capacitors when the inverter does not require energy,
but energy is pulled from the bus capacitors when the
inverter is turned on.
The DC to AC inverter also uses several power devices
arranged in a parallel connection. Each inverter mod-
ule contains an Upper and Lower device. The switch-
ing pattern for these devices determine the output volt-
age and frequency provided to the compressor motor.
Typically, drives provide a pulse of voltage at the am-
plitude of the bus voltage for a varying period of time.
This waveform is typically known as a square wave.
This OSCD contains a resistor and capacitor network
that slows down the rate at which the voltage on the
output of the OSCD will change. This network protects
the motor windings from very high peak voltage that
could cause damage to the motor winding.
A new drive logic board was designed to provide all
of the logic required to turn on and turn off all of the
power devices, turn on and off the cooling fans and
pumps, evaluate data from the input and output cur-
rent sensors, evaluate data about the input voltage, and
communicated to the OptiView™ panel.
Other sensors and boards are used to convey informa-
tion back to the OSCD Logic board (See Figure 4 on
page 13 ), and provide safe operation of the OSCD.
Each power module contains a temperature sensor that
provides temperature information back to the OSCD
logic board. Two ambient temperature sensors ensure
that the internal temperature of the OSCD does not
exceed a safe operation level. Three current sensors
monitor the output currents from the OSCD power unit
and are used to protect the drive and motor from over-
current conditions. Another 3 current sensors monitor
the input current to the OSCD to provide input current
limit, ground fault detection, and information for the
harmonic current filtering. The bus voltage is moni-
tored to verify that bus voltage is present. The line volt-
age is monitored to determine the line frequency, phase
rotation, phase loss, and amplitude.
Harmonic Filter Benefits
The OptiSpeed Compressor Drive (OSCD) system now
includes an input harmonic filter and high frequency
filter trap designed to meet the IEEE Std 519, “IEEE
Recommended Practices and Requirements for Har-
monic Control in Electrical Power Systems”. The har-
monic filter provides a means to improve the input cur-
rent waveform drawn by the OSCD from the AC line,
thus reducing the possibility of causing electrical inter-
ference with other sensitive electronic equipment con-
nected to the same power source, and reduce power loss
in the customer’s switch gear and source transformer.
In addition, the power factor of the chiller system
with this harmonic filter corrects the OSCD’s input
power factor to nearly unity over the full load range
of the product. Some passive filters may over correct
the power factor at lighter loads. Over correcting the
power factor may cause voltage ringing on the power
source that may affect other equipment, or could cause
the VSD to fault on high bus voltage.
Harmonic Filter General Information
The Harmonic Filter is no longer an option for the HYP
model of OSCD. The function of the Harmonic Filter
is now integrated into the input of the OSCD. The in-
put rectifier has fast switching power devices instead
of SCR’s and diodes. The OSCD can now control the
input current waveform to a near sine wave shape by
controlling how the rectifiers are turned on and off.
The Harmonic Filter of the past injected harmonic cur-
rent into the input of the OSCD to correct the current
waveform.
Since the Harmonic Filter is basically the input to the
OSCD there is no need for the additional pre- charge,
power unit, Harmonic Filter logic board, and contactors
for the harmonic filter of yesterday. The Harmonic Fil-
ter does not require its own pre-charge time, thus al-
lowing the chiller to start or restart in a shorter period
of time. This is an important benefit to many custom-
ers. The reductions in parts counts will improve the re-
liability of the OSCD, and ease of repair. See
Figure 5
on page 13 .
A line inductor is included on all models of HYP
OSCD's. It is needed to limit the rate of change in the
input current. Without the line inductor the input cur-
rent cannot be properly controlled and harmonic cur-
rents would be generated.