Quad Amp Hardware Reference Manual
Current Sense Board
The Current Sense Board has eight Hall Effect (LEM) modules for current sense and eight
Firing Boards
The firing boards receive their signals directly from the PMAC2 through the Logic board differential receivers and turn appropriate top and bottom IGBT on to allow current flow through a motor phase (winding). The PWM signals are
Soft Start and Shunt Regulator
The Soft Start and Shunt Regulator circuit board’s function is to provide soft charge and shunt regulation for the Quad Amplifier. It consists of a main board
The Soft Start and Shunt Regulator Main and Shunt set points (when main IGBT and shunt IGBT turn on) are set as a percentage of the nominal bus voltage for the actual AC line voltage. Therefore, set points move automatically with the line voltage. This allows operation at any line voltage above 30 VAC and prevents shunt damage under high line conditions. A condition above 250/500 VAC will cause a high line fault, which will prevent operation of the Quad Amplifier. Over voltage is set at 410/820 VDC and can be factory set lower with R2.
If there is an absence of logic power (+/- 15V), the split gate drive power supply will not be able to power the K1 relay and bus voltage is prevented from coming up because the main and soft start IGBT gates and emitters are shorted via the K1 relay (NC) contacts.
Soft Start
If there is no
Shunt Regulator
When the bus voltage rises to 114 % of the nominal bus voltage for the AC line due to a deceleration of a motor, the shunt IGBT turns on and connects the shunt resistor across the bus until the bus voltage drops to normal. The value of 114% was selected so that even at 250 VAC (about 353 VDC bus) the shunt regulator will turn on at approximately 400 VDC before the over voltage (410VDC) trips.
DC Bus Power Supply
The AC Input voltage from L1, L2, and L3 is rectified into a DC bus voltage. The DC Bus Power Supply consists of a
12 | Theory of Operation |