AP16098
UPS Main Control
Main Control Principle
Application Note
9
V1.0, 2007-03
3
Main Control Principle
As introduced in the system overview section, an Infineon 16-bit microcontroller
XC164CM is designed as the kernel of the main control circuit for the whole UPS system.
The main control functions executed by the microcontroller are briefly illustrated in Figure 4.
Figure 4
Main Control Functions Overview
To obtain output which can be filtered into sine voltage, the full-bridge inverter should be
driven by 4-channel signals with positive and negative cycles which can be originally
generated by the microcontroller. These PWM signals from the microcontrollers are first
isolated by optocouplers and then input to a flyback converter whose output can directly
drive the inverter bridge.
Fault or error status associated with inverter is monitored and processed by the
microcontroller. Once receiving fatal fault signals such as short circuit of the inverter or
over temperature of IGBTs, the microcontroller will immediately close off all PWM output
and generate disable signal to terminate the inverter operation. Therefore the protection
function for inverter against severe damage is realized. After faults or errors have been
released, all PWM signals will be resent out to run the inverter again for maintaining
normal operation.
There are many physical parameters to be sampled by the Analog-Digital converter of
the microcontroller and further calculated during main control process. These parameters
include line voltage, DC-bus voltage, primary current of output transformer, output voltage,
output current, battery voltage, IGBT temperature.
The charger module is enabled or disabled by the signal generated from the
microcontroller depending on different states. In line mode it is launched into working so as
to ensure full capacity of the battery voltage and is ceased to be inactive under the battery
mode.
