A full voltage machine open phase protection circuit

Abstract

The utility model discloses a kind of full voltage machine open-phase protection circuit, belong to protection circuit technical field, including optocoupler U1 and optocoupler U2, one end of resistance R2 is electrically connected to the input end of optocoupler U2, one end of resistance R1 is electrically connected to the input end of optocoupler U1, and the output end of optocoupler U2 is electrically connected to main circuit relay control circuit, and the output end of optocoupler U1 is electrically connected to voltage doubler relay switching circuit, the other end of resistance R2 is electrically connected to one end of pressure-sensitive resistance RV2, the other end of pressure-sensitive resistance RV2 is electrically connected to one end of pressure-sensitive resistance RV1, the other end of pressure-sensitive resistance RV1 is electrically connected to the other end of resistance R1, the other end of resistance R1 is electrically connected to one end of capacitor C2, and one end of pressure-sensitive resistance RV1 is electrically connected to the cathode of diode D4 and the cathode of diode D2.

Description

Technical Field

[0001] This utility model relates to a protection circuit, and more particularly to a phase loss protection circuit for all-voltage machines, belonging to the field of protection circuit technology. Background Technology

[0002] Existing technologies such as Figure 1 As shown, AC power supplies (A-AC220V / 380V, B-AC220V / 380V, C-380V) are connected to the circuit. Diodes D9 (12A600V), D10 (1N4007), and D12 (1N4007) serve as rectifiers or protectors to prevent reverse voltage from damaging the circuit.

[0003] The DB1 (60A / 1600V) rectifier bridge converts the input AC voltage into DC voltage, outputting DC620V-540V to provide DC power for subsequent circuits.

[0004] RV1 (14D361) Varistor: When an overvoltage occurs in the circuit, the resistance of RV1 decreases rapidly, diverting the excessive voltage to ground and protecting the circuit. Simultaneously, the voltage change signal is transmitted to the optocoupler U1 (PC817) through the RL (3W / 51K) resistor.

[0005] When optocoupler U1 receives an overvoltage signal, U1 operates, and its output signal is transmitted to the voltage doubler relay switching circuit to control the relay to operate and realize the overvoltage protection function.

[0006] Similar to RV1, the RV2 (14D431) varistor decreases in resistance when the voltage rises abnormally, thus suppressing overvoltage.

[0007] Its signal is transmitted to optocoupler U2 (PC817) via resistor R2 (3W / 51K).

[0008] When optocoupler U2 receives an overvoltage signal, it activates and outputs a signal to the main circuit relay control circuit, which then controls the main circuit relay to operate and protect the main circuit.

[0009] The output DC voltage (DC620V-540V) after rectification and protection is divided into positive and negative outputs for use by subsequent circuits.

[0010] The input circuit schematics of currently available all-voltage machines on the market are as follows: Figure 1As shown, A, B, and C represent three-phase AC 380V mains input. When the AC 380V mains input is intact, the circuit operates normally. If phase A is missing, but phases B and C are normal, the voltage is transmitted to the voltage multiplier detection circuit via phase C. The varistor RV1 (14D361) trips, the voltage multiplier relay disconnects, and the circuit does not perform voltage multiplication rectification. If phase B is missing, but phases A and C are normal, the circuit cannot form a loop, and the voltage cannot be transmitted to RV1 for voltage multiplication detection. This causes the voltage multiplier circuit to fail, resulting in AC 380V voltage multiplication. This causes the voltage across the electrolytic capacitor to be 380V * 2 * 1.414 = 1075V, far exceeding the sum of the withstand voltages of two 400V capacitors connected in series (800V), causing the capacitor to break down and be damaged. Therefore, such a circuit is very unreliable. To address this problem, a full-voltage machine phase loss protection circuit is described. Utility Model Content

[0011] The main purpose of this invention is to provide a phase loss protection circuit for all-voltage machines.

[0012] The objective of this utility model can be achieved by adopting the following technical solution: A full-voltage machine phase loss protection circuit includes optocoupler U1 and optocoupler U2; One input terminal of optocoupler U2 is electrically connected to one end of resistor R2, one input terminal of optocoupler U1 is electrically connected to one end of resistor R1, and one output terminal of optocoupler U2 is electrically connected to the main circuit relay control circuit. One output terminal of optocoupler U1 is electrically connected to the voltage doubler relay switching circuit.

[0013] Preferably, the other end of resistor R2 is electrically connected to one end of varistor RV2, the other end of varistor RV2 is electrically connected to one end of varistor RV1, and the other end of varistor RV1 is electrically connected to the other end of resistor R1.

[0014] Preferably, the other end of resistor R1 is electrically connected to one end of capacitor C2, and one end of varistor RV1 is electrically connected to the cathode of diode D4 and the cathode of diode D2.

[0015] Preferably, the anode of diode D4 is electrically connected to the cathode of diode D8, and the anode of diode D8 is electrically connected to an AC220V / 380V power supply.

[0016] Preferably, the anode of diode D8 is electrically connected to DB1, DB1 is electrically connected to the cathode of diode D7, the anode of diode D7 is electrically connected to the cathode of diode D3, the anode of diode D3 is electrically connected to the anode of diode D1, the cathode of diode D1 is electrically connected to the anode of diode D5, and the cathode of diode D5 is electrically connected to the anode of D6 and the AC220V / 380V power supply.

[0017] Preferably, the cathode of diode D6 is electrically connected to the anode of diode D2, the cathode of diode D2 is electrically connected to one end of varistor RV1 and the cathode of diode D12, the anode of diode D12 is electrically connected to the cathode of diode D10, the anode of diode D10 is electrically connected to the cathode of diode D9, the anode of diode D9 is electrically connected to the cathode of diode D11, and the anode of diode D11 is electrically connected to the anode of diode D3.

[0018] The beneficial technical effects of this utility model are as follows: This utility model provides a full-voltage machine phase loss protection circuit. This circuit can accurately detect the phase loss of three-phase AC380V grid power. No matter which phase A, B, or C is lost, the voltage can be transmitted to the voltage multiplier detection circuit through the circuit formed by the diodes.

[0019] If phase A is missing, while phases B and C are normal, the voltage of phase C can be transmitted to the detection circuit. If phase B is missing, the voltage of phase C is used for detection. If phase C is missing, the voltage of phase A is used for detection. Once a phase loss is detected, the varistor RV1 acts quickly, triggering the optocoupler U1, which in turn controls the voltage doubler relay to disconnect, stopping the voltage doubler rectification. This avoids the risk of overvoltage breakdown of the electrolytic capacitor due to phase loss and greatly improves the safety of the circuit under phase loss conditions.

[0020] Optical couplers U1 and U2 are used for signal transmission. The PC817 optocoupler provides electrical isolation, effectively preventing interference from high-voltage power to the low-voltage control circuit. This ensures that the detection signal can be stably and accurately transmitted to the voltage doubler relay switching circuit and the main circuit relay control circuit. This allows the circuit to operate reliably even in complex electrical environments, reducing the occurrence of malfunctions and ensuring the stability of equipment operation. Attached Figure Description

[0021] Figure 1 This is a circuit diagram of existing technology; Figure 2 This is a circuit diagram of a preferred embodiment of a full-voltage machine phase loss protection circuit according to the present invention. Detailed Implementation

[0022] To enable those skilled in the art to understand the technical solution of this utility model more clearly, the present utility model will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of this utility model is not limited thereto.

[0023] Example 1 The principle of the phase loss protection circuit designed in this utility model is as follows: Figure 2As shown, A, B, and C represent the three-phase AC 380V mains input. When the AC 380V mains input is complete, the circuit operates normally. Assuming phase A is missing, but phases B and C are normal, the voltage is transmitted to the voltage multiplier detection circuit via phase C. The RV1 varistor 14D361 trips, and the voltage multiplier relay disconnects, thus preventing voltage multiplication rectification. Similarly, assuming phase B is missing, but phases A and C are normal, the voltage is transmitted to the voltage multiplier detection circuit via phase C. The RV1 varistor 14D361 trips, and the voltage multiplier relay disconnects, preventing voltage multiplication rectification. Likewise, assuming phase C is missing, but phases A and B are normal, the voltage is transmitted to the voltage multiplier detection circuit via phase A. The RV1 varistor 14D361 trips, and the voltage multiplier relay disconnects, preventing voltage multiplication rectification. Therefore, regardless of which phase is missing, the voltage can form a loop through the diodes for voltage multiplication detection, thus protecting the electrolytic capacitors and making the machine more reliable.

[0024] Example 2 The diodes selected are D1-D12 (model 1N4007). 1N4007 is a commonly used general-purpose rectifier diode with a withstand voltage of 1000V and an average rectified current of 1A, which can meet the rectification and current conduction requirements of this circuit, ensuring that a loop can be effectively formed when different phase voltages are input.

[0025] The varistors used are RV1 (model 14D361) and RV2 (model 14D431). The 14D361 varistor changes its resistance rapidly when the voltage reaches approximately 360V, and is used to detect abnormal voltage conditions during phase loss. The 14D431 varistor can protect against higher overvoltages.

[0026] Optocouplers U1 (PC817) and U2 (PC817) are selected. The PC817 optocoupler can achieve electrical isolation, convert the detected voltage signal and transmit it to the subsequent control circuit, ensuring the stability and safety of signal transmission.

[0027] Resistors R1 (3W / 51K) and R2 (3W / 51K) are used. They serve functions such as voltage division and current limiting in the circuit, ensuring that components such as optocouplers operate within appropriate voltage and current ranges.

[0028] The capacitor used is C2 (474 / 630V), which is used for filtering, stabilizing the circuit voltage, and reducing the impact of voltage fluctuations on the detection circuit.

[0029] The DB1 (60A / 1600V) rectifier bridge is used to rectify the input three-phase AC voltage into DC voltage, providing a stable DC power supply for subsequent circuits.

[0030] Use professional circuit board design software (such as Altium Designer) to design the PCB. Arrange the components logically according to the circuit schematic.

[0031] The three-phase AC input interface is placed on the edge of the circuit board for easy wiring. Power components such as diodes and rectifier bridges are placed on one side with sufficient space for heat dissipation. Optocouplers, resistors, capacitors and other signal processing components are arranged in an orderly manner according to the signal flow direction to shorten the signal transmission path and reduce electromagnetic interference.

[0032] At the same time, design appropriate grounding and power layers to ensure stable electrical performance of the circuit.

[0033] After cleaning and pre-treating the prepared component leads, begin soldering. Using a soldering iron and appropriate solder wire, solder each component sequentially according to the markings on the PCB. During soldering, strictly control the soldering temperature and time. For temperature-sensitive components such as optocouplers, implement heat dissipation measures to prevent overheating damage. After soldering, carefully inspect the solder joints to ensure there are no issues such as cold solder joints, missing solder joints, or short circuits.

[0034] Before connecting the circuit board to a three-phase AC380V power supply, use a multimeter to measure the resistance between the pins of each component to check whether the circuit connection is correct and whether there are any short circuits or open circuits.

[0035] After confirming that everything is correct, connect a low-voltage DC power supply (not exceeding the rated voltage of each component) and measure the voltage of each key node, such as the input voltage of the optocoupler and the output voltage of the rectifier bridge, to ensure that all parts of the circuit are working properly and that the component parameters meet the design expectations.

[0036] Under normal operating conditions, when connected to a three-phase AC 380V mains power supply, use an oscilloscope to monitor the DC voltage output of rectifier bridge DB1. It should be within the normal range (DC 620V-540V). Observe the operating status of optocouplers U1 and U2. At this time, there should be no abnormal signal output, the voltage doubler relay should remain closed, and the circuit should be performing voltage doubler rectification normally.

[0037] Dynamic debugging - Simulating phase loss: Simulate phase A loss: Disconnect the input power supply to phase A, while maintaining normal power supply to phases B and C. Observe the circuit response. At this time, the voltage is transmitted to the voltage doubler detection circuit through the diode circuit of phase C. The varistor RV1 will activate, and the optocoupler U1 should be able to detect the signal and operate, causing the voltage doubler relay to disconnect through subsequent circuitry. Use an oscilloscope to monitor the output signal of optocoupler U1 and the control signal of the voltage doubler relay to verify whether they meet the design requirements.

[0038] Disconnect the B-phase input power supply; A and C phases are powered normally. Repeat the above steps and observe the circuit response after the voltage is transmitted through C phase to the voltage doubler detection circuit, ensuring that the RV1 varistor trips and the voltage doubler relay disconnects.

[0039] Disconnect the C-phase input power supply; phases A and B are powered normally. Observe the process of voltage transmission through phase A to the voltage multiplier detection circuit, verifying that the RV1 varistor operates, the voltage multiplier relay disconnects, and the circuit does not perform voltage multiplication rectification.

[0040] Multiple simulations were conducted to assess the accuracy and reliability of the circuit's protection actions under different phase loss conditions and varying degrees of voltage fluctuations. Based on the test results, circuit parameters (such as resistance values ​​and capacitor capacitance) were fine-tuned to optimize circuit performance, ensuring that the phase loss protection circuit operates promptly and accurately under various operating conditions. This effectively protects critical components such as electrolytic capacitors, thereby improving the machine's reliability and stability.

[0041] The above description is only a further embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the scope disclosed by the present utility model, based on the technical solution and concept of the present utility model, shall fall within the protection scope of the present utility model.

Claims

1. A phase loss protection circuit for a full-voltage machine, characterized in that: Including optocoupler U1 and optocoupler U2; One input terminal of optocoupler U2 is electrically connected to one end of resistor R2, one input terminal of optocoupler U1 is electrically connected to one end of resistor R1, and one output terminal of optocoupler U2 is electrically connected to the main circuit relay control circuit. One output terminal of optocoupler U1 is electrically connected to the voltage doubler relay switching circuit.

2. The full-voltage machine phase loss protection circuit according to claim 1, characterized in that: The other end of resistor R2 is electrically connected to one end of varistor RV2, the other end of varistor RV2 is electrically connected to one end of varistor RV1, and the other end of varistor RV1 is electrically connected to the other end of resistor R1.

3. The full-voltage machine phase loss protection circuit according to claim 1, characterized in that: The other end of resistor R1 is electrically connected to one end of capacitor C2, and one end of varistor RV1 is electrically connected to the cathodes of diode D4 and diode D2.

4. The full-voltage machine phase loss protection circuit according to claim 1, characterized in that: The anode of diode D4 is electrically connected to the cathode of diode D8, and the anode of diode D8 is electrically connected to an AC220V / 380V power supply.

5. A full-voltage machine phase loss protection circuit according to claim 1, characterized in that: The anode of diode D8 is electrically connected to DB1, DB1 is electrically connected to the cathode of diode D7, the anode of diode D7 is electrically connected to the cathode of diode D3, the anode of diode D3 is electrically connected to the anode of diode D1, the cathode of diode D1 is electrically connected to the anode of diode D5, and the cathode of diode D5 is electrically connected to the anode of D6 and the AC220V / 380V power supply.

6. A full-voltage machine phase loss protection circuit according to claim 5, characterized in that: The cathode of diode D6 is electrically connected to the anode of diode D2. The cathode of diode D2 is electrically connected to one end of varistor RV1 and the cathode of diode D12. The anode of diode D12 is electrically connected to the cathode of diode D10. The anode of diode D10 is electrically connected to the cathode of diode D9. The anode of diode D9 is electrically connected to the cathode of diode D11. The anode of diode D11 is electrically connected to the anode of diode D3.

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