In this analysis, we will explain how the current protection system works in an inverter electronic board designed to supply electricity to a compressor. Below, we detail the key steps to understand this process:
1. Initial Behavior When Starting the Equipment
When the equipment starts, current consumption is high because the compressor suctions a large amount of refrigerant gas accumulated in the evaporator, resulting in a significant current spike.
To manage this spike, the electronic board includes a protection system consisting of a PTC resistor and a contactor, both connected in parallel and traversed by a single current line.
2. Initial Operation of the System
a. State of the Contactor:
At startup, the contactor is disconnected as it has not yet received the activation signal from the controller.
As a result, all initial current flows through the PTC resistor.
b. Initial Current Regulation:
- The PTC resistor, with an initial resistance of 40 ohms (in this example), regulates the current flow to the compressor, mitigating the impact of the current spike.
- As the current flows, the PTC resistor heats up, increasing its temperature and resistance to 60 ohms, further reducing the current flow.
3. Contactor Activation
Once the current sensor on the electronic board detects a safe current consumption, the controller sends a 12V control signal to the contactor to activate it.
When the contactor activates, the current flow is primarily redirected through its switch, which has virtually no resistance, enabling safe and efficient current flow.
4. Indicators of System Failure
a. Issues with the PTC Resistor:
- If the PTC resistor heats up but does not increase its resistance, this may indicate a failure in the contactor, which fails to activate.
b. Constant High Current Consumption:
- If the current consumption remains high and the contactor never activates, there could be a short circuit somewhere on the electronic board, forcing the PTC resistor to remain in continuous operation.
c. Recommended Checks:
- Visually inspect the PFC circuit on the electronic board for any signs of damage.
- Perform a thorough review of the IPM electronic circuit to identify potential faults.
5. Importance of Diagnostics
The proper functioning of the current protection system is critical to preventing damage to the compressor and other components of the electronic board.
At the first sign of a fault, it is advisable to perform the recommended checks to ensure the safety and efficiency of the system.
