The overload protection function of portable power station is realized through the cooperative work of hardware detection circuit+intelligent control chip+executive protection element. The core is to monitor the output power/current in real time, and when it exceeds the rated threshold, quickly cut off the circuit or limit the output, so as to avoid the equipment and electrical components from being damaged due to overload, and even lead to safety accidents such as fire.
First, the core working principle: three-layer linkage protection mechanism
The essence of overload protection is a closed-loop process of "monitoring-judging-executing", and the three core components have a clear division of labor to ensure millisecond response.
Monitoring layer: collecting current/power data in real time.
In the output loop of portable power station, current sensors (such as shunt and Hall sensor) and voltage sensors are built in to collect the current and voltage data at the output end in real time. These sensors have extremely high accuracy, which can capture tiny current fluctuations and ensure the accuracy of data acquisition.
The collected data will be transmitted to the core control chip (MCU) in real time. The chip calculates the current output power through the formula "power = voltage× current" and compares it with the rated output power of the product in real time.
Judgment layer: threshold comparison of smart chips
The control chip (MCU) is the "brain" of overload protection, and the rated power/current threshold of the product is written in advance (for example, in a power station with a rated output of 1000W, the threshold is usually set to 1000-1100W, and a certain buffer space is reserved).
When the calculated real-time power/current exceeds the set threshold, the chip will immediately judge it as "overload state" and send a protection instruction to the execution element; If the power is within the threshold range, the normal output will be maintained and protection will not be triggered.
Some high-end products will also add "delay judgment" logic. Short-term power peaks (such as the instant when electrical appliances are started) will not trigger protection, so as to avoid frequent power outages affecting the experience. Only when the threshold is continuously exceeded will protection be started.
Execution layer: quickly cut off or limit output
After the control chip sends an instruction, the executive component will respond immediately and realize overload protection in two ways:
Directly cut off the circuit: the most common way is to control the relay or circuit breaker to cut off the output circuit. At this time, all the output interfaces stop supplying power, and the display screen of the equipment will display an "overload" prompt and give an audible and visual alarm. It is necessary for the user to turn off the overload electrical appliance and manually press the reset button to restore the power supply.
Dynamic limiting output: Some high-end products adopt "soft protection" mode, and the output current is adjusted by the control chip to limit the power within the rated range to avoid direct power failure. For example, when the 1200W electrical appliance is connected, the 1000W rated power station will automatically limit the output power to 1000W, and at the same time prompt overload, giving consideration to safety and continuity of use.
Second, the protection logic of different overload scenarios
According to different overload situations, the portable power station will trigger different protection strategies to ensure safety and improve the use experience.
Mild overload (power exceeds the threshold by 10%-20%): usually trigger "soft protection", limit the output power and give an alarm to remind users to turn off some high-power appliances; If the user fails to handle it in time, the circuit will be automatically cut off after 1-3 minutes of continuous overload.
Severe overload (the power exceeds the threshold by more than 20%): immediately trigger the "hard protection", cut off the output circuit in milliseconds to avoid overheating of the line and burning of components caused by large current, and at the same time send out a strong audible and visual alarm to remind users to check the overloaded equipment.
Instantaneous peak overload (for example, the motor and compressor start at the moment): the power of this kind of equipment will reach 2-3 times of the rated power when it is started, and some power stations will set a "peak buffer time" (for example, 1-3 seconds). Short peak overload will not trigger protection, and the power will return to normal after the equipment is started, so as to avoid frequent power outages affecting the use.
Three, the core components of overload protection
The reliability of overload protection function depends on the performance of the following key components:
Current sensor: it is responsible for accurately collecting the output current, which is the basis of overload judgment. The higher the accuracy, the more accurate the protection response.
MCU control chip: equivalent to the "decision center", the operation speed directly determines the protection response time, and the high-end chip can achieve microsecond response.
Relay/Circuit Breaker: The core component to cut off the circuit needs to have high current resistance and quick response ability to ensure that the circuit can be reliably cut off under large current.
Fuse: As the "last line of defense", if the relay/circuit breaker fails, excessive current will blow the fuse, completely cut off the circuit and avoid equipment fire.
Fourth, the coordination of overload protection and other protection functions
The overload protection of portable power station does not exist in isolation, but forms linkage with over-temperature protection, short-circuit protection and over-voltage protection to build an all-round safety protection system.
For example, when the circuit temperature rises sharply due to overload, overload protection and overtemperature protection will be triggered at the same time: firstly, the circuit will be cut off through overload protection; if the temperature continues to rise, the overtemperature protection will be further started, and the battery power supply circuit will be cut off, thus completely eliminating safety risks.
