Electrolytic capacitor overvoltage protection circuit for outdoor unit of variable frequency air conditioner

Abstract

The utility model relates to a power electronic equipment protection technology, in particular to an electrolytic capacitor overvoltage protection circuit for an outdoor unit of a variable frequency air conditioner, which comprises a pre-charging circuit, a bypass relay, a rectifier bridge circuit, an electrolytic capacitor, an alternating current and direct current voltage detection circuit and an MCU (Microprogrammed Control Unit) controller, according to the electrolytic capacitor overvoltage protection circuit for the outdoor unit of the variable frequency air conditioner, through a real-time voltage monitoring and dynamic protection mechanism, the service life of the electrolytic capacitor is effectively prolonged, and the operation reliability of the variable frequency air conditioner is improved.

Description

Technical Field

[0001] This utility model relates to a power electronic equipment protection technology, specifically to an overvoltage protection circuit for an electrolytic capacitor in an outdoor unit of a variable frequency air conditioner. This circuit can effectively prevent damage to the electrolytic capacitor due to overvoltage through real-time voltage monitoring and intelligent control, and belongs to the fields of power electronic protection circuits and variable frequency air conditioner control technology. Background Technology

[0002] With the widespread application of inverter technology in the air conditioning industry, the performance and energy efficiency of inverter air conditioners have been significantly improved. However, in actual operation, especially in areas with large fluctuations in grid voltage, inverter air conditioners often face the problem of abnormally high input voltage. This excessively high input voltage will directly affect the electrolytic capacitor, causing it to withstand a voltage exceeding its rated withstand value, which will lead to damage or failure of the electrolytic capacitor. This not only affects the normal operation of the inverter air conditioner but may also cause circuit failures or even safety issues.

[0003] Existing overvoltage protection circuits typically employ simple hardware protection methods, such as using voltage-limiting diodes or energy-dissipating resistors to absorb excess voltage. However, these methods are only applicable to certain fixed voltage fluctuation ranges and are difficult to adapt to dynamic voltage changes in complex power grid environments. Furthermore, some solutions utilize purely analog circuits for overvoltage protection, but these still have limitations in response speed and precise control.

[0004] Therefore, designing an overvoltage protection circuit that can monitor the input voltage in real time and dynamically adjust the protection status to efficiently protect electrolytic capacitors from overvoltage damage has become an important direction for technological development in the industry. Summary of the Invention

[0005] This invention aims to solve the problem of electrolytic capacitors in outdoor units of inverter air conditioners being damaged due to abnormally high input voltage in the prior art. It provides an overvoltage protection circuit for electrolytic capacitors in outdoor units of inverter air conditioners. Through real-time voltage monitoring and dynamic protection mechanisms, it effectively extends the service life of electrolytic capacitors and improves the operational reliability of inverter air conditioners.

[0006] To achieve the above objectives, this utility model provides an overvoltage protection circuit for an electrolytic capacitor used in an outdoor unit of a variable frequency air conditioner, comprising: a pre-charging circuit, including a pre-charging PTC resistor, used to limit the current when the circuit starts up and to buffer the input voltage in the protection state;

[0007] A bypass relay is connected in parallel with the pre-charging circuit to switch the circuit's operating state;

[0008] A rectifier bridge circuit is connected to the input AC power supply and is used to rectify AC power into DC power.

[0009] An electrolytic capacitor is connected to the output end of the rectifier bridge circuit, and is used for filtering and stabilizing the rectified voltage.

[0010] An AC / DC voltage detection circuit is connected to the input AC power supply and the electrolytic capacitor respectively, and is used for detecting the input AC voltage and the DC voltage of the electrolytic capacitor in real time.

[0011] An MCU controller is electrically connected to the AC / DC voltage detection circuit, and is used for controlling the on-off of the bypass relay according to the detected voltage value, so as to protect the electrolytic capacitor.

[0012] Preferably, the pre-charging circuit comprises a pre-charging PTC resistor connected in parallel with the bypass relay, and is used for buffering the input current when the bypass relay is disconnected.

[0013] Preferably, the AC / DC voltage detection circuit comprises an AC voltage detection module for detecting the input AC voltage, and a DC voltage detection module for detecting the DC voltage of the electrolytic capacitor.

[0014] Preferably, the MCU controller comprises a delay logic module, which is used for controlling the bypass relay to be disconnected when the input AC voltage is detected to be higher than 318V or the DC voltage of the electrolytic capacitor is detected to be higher than 450V and lasts for 1 second.

[0015] Preferably, the bypass relay is connected with the MCU controller through a driving circuit, and is used for receiving a control signal and switching the working state.

[0016] Preferably, the electrolytic capacitor has a withstand voltage of 450V, and the input voltage range of the AC / DC voltage detection circuit is 160V to 270V.

[0017] The pre-charging circuit, the bypass relay, the AC / DC voltage detection circuit and the MCU controller are reasonably designed and integrated, so that the operation reliability of the frequency conversion air conditioner outdoor unit under a complex power grid environment is significantly improved, and the specific technical effects are as follows:

[0018] Prevent the electrolytic capacitor from being damaged: the input AC voltage and the DC voltage of the electrolytic capacitor are monitored in real time, when the voltage is detected to be abnormally high and lasts for a certain time, the circuit is quickly switched to the protection state, the pre-charging resistor is used for buffering the voltage, the damage of the electrolytic capacitor caused by overvoltage is avoided, and the core component of the air conditioning system is effectively protected.

[0019] Prolong the service life of the equipment: while effectively preventing the electrolytic capacitor from being damaged by overvoltage, the damage risk of other circuit components caused by abnormal voltage is reduced, the overall service life of the frequency conversion air conditioner outdoor unit is prolonged, and the equipment maintenance and replacement cost is reduced.

[0020] Fast response speed and accurate protection: through real-time detection of the MCU controller and delay trigger logic, the utility model can quickly enter the protection state after the voltage anomaly lasts for 1 second, which not only avoids the misoperation caused by short-time voltage fluctuation, but also provides accurate protection when the voltage is continuously abnormal, thereby improving the intelligent level of the system.

[0021] Adapt to complex power grid environment: the circuit design can adapt to a wide input voltage range of 160V to 270V, and can effectively deal with the case that the alternating voltage abnormally rises to 318V and above, and is especially suitable for areas with large power grid voltage fluctuation.

[0022] High reliability of protection mechanism: the dynamic protection mechanism is adopted, the bypass relay provides a direct current path during normal operation, which reduces the additional power consumption; in the protection state, the voltage buffer is realized through the pre-charge circuit, the protection mechanism is stable and reliable, and the continuous operation of the air conditioning system is ensured.

[0023] Economical and efficient: the protection circuit structure of the utility model is simple, and the existing hardware resources are optimized, which not only reduces the additional hardware cost, but also improves the performance and stability of the system, and has high practical value and economic benefit. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the utility model. DETAILED DESCRIPTION Embodiment 1

[0025] The utility model provides a kind of overvoltage protection circuit of electrolytic capacitor for frequency conversion air conditioner outdoor unit, comprising: pre-charge circuit, including pre-charge PTC resistance, for limiting current when circuit starts, and buffering input voltage under protection state;

[0026] Bypass relay, it is connected in parallel with the pre-charge circuit, for switching circuit working state;

[0027] Rectifier bridge circuit, connect with input ac power supply, for alternating current is rectified into direct current;

[0028] Electrolytic capacitor, connect at the output end of the rectifier bridge circuit, for filtering and voltage stabilizing after rectification;

[0029] AC / DC voltage detection circuit is connected to the input ac power supply and electrolytic capacitor respectively, for real-time detection input ac voltage and the direct current voltage of electrolytic capacitor;

[0030] MCU controller, it is electrically connected with the AC / DC voltage detection circuit, for according to the voltage value detected control the on-off of the bypass relay, to protect the electrolytic capacitor. Embodiment 2

[0031] The difference between the present embodiment and embodiment 1 is that the present embodiment further comprises the following features:

[0032] The pre-charge circuit comprises a pre-charge PTC resistor connected in parallel with the bypass relay for buffering the input current when the bypass relay is disconnected.

[0033] Preferably, the AC / DC voltage detection circuit comprises an AC voltage detection module for detecting the input AC voltage and a DC voltage detection module for detecting the DC voltage of the electrolytic capacitor.

[0034] Preferably, the MCU controller comprises a delay logic module for controlling the bypass relay to be disconnected when the input AC voltage is detected to exceed 318V or the DC voltage of the electrolytic capacitor is detected to exceed 450V and the condition lasts for 1 second.

[0035] Preferably, the bypass relay is connected with the MCU controller through a driving circuit for receiving the control signal and switching the working state.

[0036] Preferably, the voltage resistance of the electrolytic capacitor is 450V and the input voltage range of the AC / DC voltage detection circuit is 160V to 270V.

Claims

1. An overvoltage protection circuit for an electrolytic capacitor of a variable frequency air conditioner outdoor unit, comprising an input AC power source, characterized in that, The application relates to a circuit for protecting an electrolytic capacitor, which comprises the following parts: a pre-charging circuit comprising a pre-charging PTC resistor, which is used for limiting current when the circuit starts and buffering input voltage in a protection state; a bypass relay connected in parallel with the pre-charging circuit, which is used for switching the working state of the circuit; a rectifier bridge circuit connected with an input AC power supply, which is used for rectifying AC power into DC power; an electrolytic capacitor connected with the output end of the rectifier bridge circuit, which is used for filtering and stabilizing the rectified voltage; an AC / DC voltage detection circuit connected with the input AC power supply and the electrolytic capacitor respectively, which is used for detecting the input AC voltage and the DC voltage of the electrolytic capacitor in real time; an MCU controller connected with the AC / DC voltage detection circuit, which is used for controlling the on-off of the bypass relay according to the detected voltage value, so as to protect the electrolytic capacitor.

2. The overvoltage protection circuit for an electrolytic capacitor of a variable frequency air conditioner outdoor unit according to claim 1, characterized in that, The pre-charging circuit comprises a pre-charging PTC resistor connected in parallel with the bypass relay, which is used for buffering input current when the bypass relay is disconnected.

3. The overvoltage protection circuit for an electrolytic capacitor of a variable frequency air conditioner outdoor unit according to claim 1, characterized in that, The AC / DC voltage detection circuit comprises an AC voltage detection module for detecting the input AC voltage and a DC voltage detection module for detecting the DC voltage of the electrolytic capacitor.

4. The overvoltage protection circuit for an electrolytic capacitor of a variable frequency air conditioner outdoor unit according to claim 1, characterized in that, The MCU controller comprises a delay logic module, which is used for controlling the bypass relay to be disconnected when the input AC voltage is detected to be higher than 318V or the DC voltage of the electrolytic capacitor is detected to be higher than 450V and the state lasts for 1 second.

5. The overvoltage protection circuit for an electrolytic capacitor of a variable frequency air conditioner outdoor unit according to any one of claims 1, wherein The bypass relay is connected with the MCU controller through a driving circuit, which is used for receiving control signals and switching the working state.

6. The overvoltage protection circuit for an electrolytic capacitor of a variable frequency air conditioner outdoor unit according to any one of claims 1 to 5, characterized in that, The voltage resistance value of the electrolytic capacitor is 450V, and the input voltage range of the AC / DC voltage detection circuit is 160V to 270V.

7. The overvoltage protection circuit for an electrolytic capacitor of a variable frequency air conditioner outdoor unit according to any one of claims 1, wherein The circuit is installed on the main control board of a variable frequency air conditioner outdoor unit and is electrically connected with the whole machine control system.

Images