At this stage, the following protection methods are suitable for PCB electronic products, automated electronic control equipment, and power semiconductor devices:
1. Fuse Method
This is a commonly used protection approach. The fuse is typically connected in series at the power input end of the circuit to regulate the total current. Its principle relies on cutting off the power supply to achieve protection by relying on the increased fault current that flows through the fuse when a circuit issue occurs, causing it to heat up and melt. The fuse method boasts advantages such as simple implementation, easier maintenance, lower cost, and complete power cut-off during protection, making it widely used in PCB electronic circuits and equipment. However, since the fuse handles the total circuit current, it does not respond effectively to changes in the current of a single power semiconductor device. Additionally, due to the fuse’s relatively slow melting speed, it only blows after the fault current significantly increases, often only protecting against fault expansion rather than safeguarding the power semiconductor device itself.
1. This method connects detection elements (such as detection resistors, transformers, etc.) in series with the input of the main circuit power supply. It obtains the corresponding current or voltage signal through the voltage drop or current magnitude in the detection circuit. This signal is then amplified by the circuit and compared with the protection circuit’s action threshold to determine whether to initiate protection.
2. Given the advancements in electronic technology, this protection method offers improved sensitivity and response speed compared to the fuse method. However, it still detects the total current of the circuit. Since the operating current of a faulty power semiconductor device is only a fraction of the total current—often just a few percent or even one-tenth—its change may not trigger an effective response from the protection circuit.
3. Consequently, this method often reacts only after the PCB fault current has developed, leading to a lag between detection results and protection action. This delay makes it inadequate for meeting the protection requirements for power semiconductor devices. Thus, similar to fuses, this method primarily prevents further damage after the power semiconductor device has been compromised and a severe over-current fault has occurred. It still cannot provide proactive protection for power devices.
4. **Detecting the Working Current of Power Devices**
5. This method is currently more commonly used for protecting power semiconductor devices and offers a certain level of protection. It involves placing a detection element (such as a resistor or current transformer) in series with the working current path of the protected power semiconductor device. By detecting the working current of the device, a current or voltage signal is obtained, which is then processed by the circuit. Fault signals are protected by a fuse or by shutting off the power supply.
6. The working principle and circuit structure of this method are similar to those of the main circuit current detection method. The difference lies in the detection object being the working current of the protected device, which results in higher sensitivity and better effectiveness. When electronic devices are used to interrupt the current path for protection, they can respond to overcurrent faults.
7. However, since this method still relies on current detection, the fault signal is detected and protected only after the fault has occurred and the device has been exposed to high voltage and large current. This can still lead to signal acquisition lag. If the power margin of the protected device is small or the circuit failure is severe, the device may still be damaged immediately. Conversely, if the device’s power margin is large and the failure is less severe, the device is generally not damaged.
8. **Parallel Detection of Power Device Voltage Method**
9. As the name implies, this method involves connecting the protection circuit in parallel with the protected power device. It detects the voltage of the device during operation and assesses whether the circuit is faulty based on this voltage. This method employs an in-situ protection approach by forcibly cutting off the control signal to the protected device, thereby stopping its operation and ensuring protection.
10. Because this method detects voltage signals, it can identify faults immediately when the circuit becomes abnormal and provide protection before the PCB fault current forms, thus avoiding the impact of fault current on the device.
11. The protection method has the following advantages:
1. The protection circuit is connected in parallel, meaning no components are in series with the main working circuit. This maintains high power utilization and eliminates heat sources.
2. The detection object is the working voltage of the protected power device. Consequently, the protection circuit has high input impedance, low power consumption, and high detection accuracy.
3. Since it detects the working status of the protected device itself and applies protection directly to the device, it is highly targeted and provides timely, reliable protection.
12. The main disadvantage of this protection circuit is that it only provides qualitative detection of the working state of the protected PCB device. Therefore, in voltage-controlled power devices, it can only ideally protect against load short-circuits and severe over-current faults.
13. **Parallel Type Detection Working Pressure Drop Method**
14. Due to the on-resistance of the power semiconductor device itself, any overload or overcurrent will increase its saturation voltage drop or working voltage drop. Regardless of the device’s working state, there will be a corresponding working voltage drop. By monitoring this voltage drop when the power semiconductor device is on, it is possible to assess the degree of overcurrent and overload based on the magnitude of the voltage drop.
15. The above outlines some relevant knowledge regarding PCB power devices. Continuous advancements in power devices depend on the ongoing efforts of researchers to drive technological progress and enhance the efficiency of PCB electronic products.
1. Fuse Method
This is a commonly used protection approach. The fuse is typically connected in series at the power input end of the circuit to regulate the total current. Its principle relies on cutting off the power supply to achieve protection by relying on the increased fault current that flows through the fuse when a circuit issue occurs, causing it to heat up and melt. The fuse method boasts advantages such as simple implementation, easier maintenance, lower cost, and complete power cut-off during protection, making it widely used in PCB electronic circuits and equipment. However, since the fuse handles the total circuit current, it does not respond effectively to changes in the current of a single power semiconductor device. Additionally, due to the fuse’s relatively slow melting speed, it only blows after the fault current significantly increases, often only protecting against fault expansion rather than safeguarding the power semiconductor device itself.
1. This method connects detection elements (such as detection resistors, transformers, etc.) in series with the input of the main circuit power supply. It obtains the corresponding current or voltage signal through the voltage drop or current magnitude in the detection circuit. This signal is then amplified by the circuit and compared with the protection circuit’s action threshold to determine whether to initiate protection.
2. Given the advancements in electronic technology, this protection method offers improved sensitivity and response speed compared to the fuse method. However, it still detects the total current of the circuit. Since the operating current of a faulty power semiconductor device is only a fraction of the total current—often just a few percent or even one-tenth—its change may not trigger an effective response from the protection circuit.
3. Consequently, this method often reacts only after the PCB fault current has developed, leading to a lag between detection results and protection action. This delay makes it inadequate for meeting the protection requirements for power semiconductor devices. Thus, similar to fuses, this method primarily prevents further damage after the power semiconductor device has been compromised and a severe over-current fault has occurred. It still cannot provide proactive protection for power devices.
4. **Detecting the Working Current of Power Devices**
5. This method is currently more commonly used for protecting power semiconductor devices and offers a certain level of protection. It involves placing a detection element (such as a resistor or current transformer) in series with the working current path of the protected power semiconductor device. By detecting the working current of the device, a current or voltage signal is obtained, which is then processed by the circuit. Fault signals are protected by a fuse or by shutting off the power supply.
6. The working principle and circuit structure of this method are similar to those of the main circuit current detection method. The difference lies in the detection object being the working current of the protected device, which results in higher sensitivity and better effectiveness. When electronic devices are used to interrupt the current path for protection, they can respond to overcurrent faults.
7. However, since this method still relies on current detection, the fault signal is detected and protected only after the fault has occurred and the device has been exposed to high voltage and large current. This can still lead to signal acquisition lag. If the power margin of the protected device is small or the circuit failure is severe, the device may still be damaged immediately. Conversely, if the device’s power margin is large and the failure is less severe, the device is generally not damaged.
8. **Parallel Detection of Power Device Voltage Method**
9. As the name implies, this method involves connecting the protection circuit in parallel with the protected power device. It detects the voltage of the device during operation and assesses whether the circuit is faulty based on this voltage. This method employs an in-situ protection approach by forcibly cutting off the control signal to the protected device, thereby stopping its operation and ensuring protection.
10. Because this method detects voltage signals, it can identify faults immediately when the circuit becomes abnormal and provide protection before the PCB fault current forms, thus avoiding the impact of fault current on the device.
11. The protection method has the following advantages:
1. The protection circuit is connected in parallel, meaning no components are in series with the main working circuit. This maintains high power utilization and eliminates heat sources.
2. The detection object is the working voltage of the protected power device. Consequently, the protection circuit has high input impedance, low power consumption, and high detection accuracy.
3. Since it detects the working status of the protected device itself and applies protection directly to the device, it is highly targeted and provides timely, reliable protection.
12. The main disadvantage of this protection circuit is that it only provides qualitative detection of the working state of the protected PCB device. Therefore, in voltage-controlled power devices, it can only ideally protect against load short-circuits and severe over-current faults.
13. **Parallel Type Detection Working Pressure Drop Method**
14. Due to the on-resistance of the power semiconductor device itself, any overload or overcurrent will increase its saturation voltage drop or working voltage drop. Regardless of the device’s working state, there will be a corresponding working voltage drop. By monitoring this voltage drop when the power semiconductor device is on, it is possible to assess the degree of overcurrent and overload based on the magnitude of the voltage drop.
15. The above outlines some relevant knowledge regarding PCB power devices. Continuous advancements in power devices depend on the ongoing efforts of researchers to drive technological progress and enhance the efficiency of PCB electronic products.
