Hypertherm Powermax45 Service Manual - Manual (Page 78)

TroubleshooTing and sysTem TesTs
5-2
powermax
45 Service Manual
Theory of operation
general
Refer to the following functional description topics, to Sequence of operation on page 5-4, and to the Wiring
Diagrams section.
200–240 V CSA and 230 V Ce 1-phase power supply functional description
AC power enters the system through the power switch (S1) to the input diode bridge (D48). The voltage from the diode
bridge supplies the power factor correction (PFC) boost converter, which provides a nominal 385 VDC bus voltage. The
bus voltage then supplies voltage and current to the inverter and the flyback circuit power supply (DC to DC converter)
on the power board (PCB2). The power board provides noise suppression and spike protection. A “soft start” is
implemented via the power board resistor and relays (K1, K2).
The PFC boost converter consists of an insulated gate bipolar transistor (IGBT Q2), PFC choke, and control circuit.
It provides a 385 VDC bus voltage when the input AC voltage is between 200 and 240 VAC.
The inverter consists of a dual IGBT package (Q3), the power transformer, a current sense transducer, and the control
circuit. The inverter operates as a pulse-width modulated half-bridge circuit driving an isolation transformer. The
secondary of the isolation transformer is rectified by the output bridge (D38).
The output circuitry consists of 2 current sense transducers located on the power board, the pilot arc IGBT (inside the
D38 module), and the output choke.
The control board’s digital signal processor (DSP) monitors and regulates the system’s operation and safety circuits.
The amperage adjustment knob is used to set the output current to the desired value between 20 and 45 amps. The
system compares the set-point to the output current by monitoring the current sense transducers and adjusting the
pulse-width output of the inverter IGBTs (Q3). A trip coil on the power switch provides over-voltage protection.
400 V Ce 3-phase power supply functional description
AC power enters the system through the power switch (S1) to the input diode bridge (D48). The voltage from the
diode bridge supplies the power factor correction (PFC) choke, which provides a nominal 560 VDC bus voltage. The
bus voltage then supplies voltage and current to the inverter and the flyback circuit power supply (DC to DC converter)
on the power board (PCB2). The power board provides noise suppression and spike protection. A “soft start” is
implemented via the power board resistor and relays (K2).
The inverter consists of a dual IGBT package (Q2), the power transformer, a current sense transducer, and the control
circuit. The inverter operates as a pulse-width modulated half-bridge circuit driving an isolation transformer. The
secondary of the isolation transformer is rectified by the output bridge (D40).
The output circuitry consists of 2 current sense transducers located on the power board, the pilot arc IGBT (inside the
D40 module), and the output choke.
The control board’s digital signal processor (DSP) monitors and regulates the system’s operation and safety circuits.
The amperage adjustment knob is used to set the output current to the desired value between 20 and 45 amps. The
system compares the set-point to the output current by monitoring the current sense transducers and adjusting the
pulse-width output of the inverter IGBT (Q2).