Service manual

the output of the switching leg filtered by a LC filter to get clean and stable sine wave the output
voltage.
5.2.4 Global Controller
The Global Controller of UPS composed of following major circuits as following.
(1) CPU Central Processor Unit
(2) Signal conditioning circuit
(3) Regulation & Protection circuit
(4) Output buffering circuit
(5) Communication interface
The CPU can be regards the brains of the UPS, in charge of signal detecting, measurement,
processing, timing control, inverter operating control, protection, communication.
To control the UPS, the status of the UPS must be monitored, Difference kinds of sensor are
widely used in the UPS, due the pure condition of the signal given but the sensors, so, Signal
conditioning circuit is use to attenuate / amplify / filter the signal given by the sensor, became
suitable to be processed by the CPU.
The regulation network of the inverter, forming a close loop controller, enable inverter run
stably, and get desired performance, such as less distortion, good dynamic response
performance, etc.
The global controller also implement following protection function:
1. Overload Protection
2. Cycle by Cycle Current Limitation
3. Battery over or under voltage shut down
4. Inverter output abnormal protection
5. Over temperature protection
6. Bus over-voltage protection
7. Fans lock protection
Due to the high level integration, the global controller is not desired to maintenance or repair
out of manufacture factory. There are two methods to identify the status of global controller.
The first one is to test with test fixture; the second is to test the global controller on a PSDR that
has been verified OK.
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