1. Introduction A newly purchased bridge crane (hereinafter referred to as QC) and six tire-type gantry cranes (hereinafter referred to as RTG) in Qingzhou Port District of Fuzhou are all driven by Yaskawa Inverter. Although the models are different, (6R6CR5, 616G5, 616H5, etc.), but the main circuit is the same, but the control board and the driver board is not the same, so understand the structure of the inverter, the electrical characteristics of the main device and the role of common parameters and common Troubleshooting is more and more important for practical work. According to the author's experience in random debugging and maintenance, it provides a reference for the operation of this type of equipment.
2. Yaskawa's variable frequency speed control structure and its working principle According to n=120f/p (where n=motor speed, f=motor stator-side power supply frequency, p=motor pole pair number), the number of pole pairs in the asynchronous motor is unchanged. In this case, as long as the power frequency f is changed, the speed regulation of the asynchronous motor can be realized. In the container crane, the main circuit for the asynchronous motor (voltage, frequency adjustable) contains Yaskawa Inverter, which works in the form of AC-DC-AC and provides various control signal loops for the inverter. It is called control loop, as shown in Figure 1, which includes the following parts:
(1) Rectifier bridge: UAC of three-phase alternating current is rectified into direct current UDC.
(2) Charge suppression resistor R1: According to the formula i=(UAC-UDC)/r, it can be seen that since r is a bridge rectifier equivalent resistance is small, the charging current I becomes large. In order to prevent the electrolytic capacitor from being broken down, it is necessary to install a charge suppression resistor R1 and a bypass contactor MC, thereby functioning as a current limiter.
(3) Bypass contactor MC: When the capacitor charge reaches 80%, the MC is closed and R1 is bypassed, so the element must be maintained periodically.
(4) Filter capacitor C: With energy storage function, life can reach 5~8 years. When the grid voltage drops 30%, the voltage UC at both ends of the capacitor can be maintained for 10s for the inverter to work; when the grid voltage drops 50%, The voltage UC across the capacitor can be maintained for 2s for the inverter to work.
(5) Charging indicator: When the charging voltage reaches 27V or more, the indicating lamp will be on. Therefore, after the power of the inverter is cut off, the internal components of the inverter can be repaired only when the indicating lamp is completely extinguished, to avoid electric shock.
(6) Inverter loop (bridge) master device (IGBT): Fully known as high-power bipolar insulated gate field effect hall, including gate, source, drain, characterized by voltage control device, low gate trigger power , High switching frequency, good characteristic suppression, that is, the on-state voltage drop, open leakage current are very small, and the service life can reach 20 years.
(7) A resistance-capacitance absorption loop is connected in parallel at both ends of the IGBT, which can suppress high-frequency harmonics because the motor is an inductive load and di/dt cannot be changed quickly.
(8) Current transformer CT collects the main circuit current, which is used as a current regulator ACR. To prevent damage to the asynchronous motor and the inverter when an abnormality such as overload occurs, the inverter stops operation or suppresses voltage and current values.
(9) Main control board: It is a 32-bit microprocessor that compares the external speed and torque commands with the current and voltage signals of the detection circuit to determine the output voltage and frequency of the inverter.
(10) Driver board: It is the circuit that drives the inverter main device IGBT. It is isolated from the control circuit and controls the turn-on and turn-off of the IGBT. If the IGBT is damaged, the associated driver board is generally damaged.
(11) Speed ​​detector PG: It is a pulse encoder, mounted on the output shaft of the asynchronous motor, and collecting the speed signal. It is connected to the internal PG card of the inverter and transmits the speed to the arithmetic circuit so that the motor can run according to the given command.
(12) I/F communication board: It is better to exchange the input and output signals with the inverter for human-machine exchange, including the input of various internal parameters.
3. Analysis and Handling of Common Faults of Yaskawa Inverter Yaskawa's inverters are equipped with a hand actuator on the electrical cabinet door, and display various parameter values ​​and fault codes. The analysis is based on our experience as follows:
(1) The inverter shows OC, that is, overcurrent. It has instantaneous memory function, and it is not settable by man. It is mainly used for inverter load-side short circuit, etc. When the current flowing through the inverter device reaches the rated current of 2.7 to 3 times, Instantly stop the inverter operation and cut off the power supply; the inverter output current reaches an abnormal value and the inverter will also stop running. Specific treatment can be checked one by one as follows:
1 whether the acceleration time is too short;
2 whether the torque increase parameter is too large;
3 Is the load externally short-circuited or over-weighted? For example, if there are two motor drives in the car organization, one of them may be damaged, and the other may experience over-current.
4PG detection circuit is abnormal, including PG card and pulse encoder;
5 whether the current transformer is abnormal;
6 Main power device IGBT is abnormal;
7 If there is no problem with the above, you can disconnect the output current negative inductor and DC detection point, run after reset, and there is overcurrent, it is likely that the main control board or trigger board has failed.
(2) Inverter display OL is overload, which is mainly used for the inverter output current exceeds the rated value, and continues to circulate for more than the specified time, in order to prevent damage to the inverter devices, wires, etc., to stop the inverter. Specifically divided into the following three:
1 If the current exceeds 150% of the rated current for 60s, the OL1 fault is reported, indicating that the motor is overloaded;
2 If the current exceeds the rated current for 180% for 10s, it will report OL2 fault, indicating that the inverter is overloaded;
3 When the current exceeds the rated current of 200% for 5 seconds, the OL3 fault is reported, indicating that the system is overloaded, that is, the torque protection of the steel structure.
No matter what kind of overload, it is because the GD2 (inertia) of the load is too large or is generated due to the load over the ambassador motor stalled, so that for the failure of the inverter that has been put into operation, the condition of the load must be checked; for the new The installed inverter has this type of fault, which may be caused by incorrect setting of the V/F curve or a problem with the motor parameter setting. For example, a newly installed inverter drives a variable-frequency motor with a rated parameter of 220V/50Hz, and the inverter is set to 380V/50Hz at the factory, causing magnetic saturation after the motor has run for a period of time to reduce the speed of the motor and generate heat. And overloaded.
(3) Inverter display GF is the load short circuit to ground, which has transient function, that is, the three-phase phase current deviation is greater than 50% of the rated current. The specific reasons are as follows:
1 motor insulation is not good or three-phase and phase imbalance;
2 Abnormal inverter, mainly control loop.
(4) The inverter shows OH that the inverter is overheated and can be divided into OH1 and OH2. The reasons are as follows:
1 whether the two sets of fans in the inverter cabinet are abnormal;
2 The ambient temperature is too high;
3 Frequent overloading;
4 Abnormal phenomenon such as excessive dust in the thermal detection device.
(5) The inverter displays OS, namely overspeed, hardware and software overspeed, and the set values ​​are 115% and 110% of the rated speed. At this time, check whether the PG feedback is normal.
(6) The inverter displays UV or undervoltage, that is, the DC bus voltage fault is detected. When designing the startup circuit of the inverter, a general designer selects a small current limiting resistor R1 in order to reduce the volume of the inverter, and its resistance is 10~50Ω and the power is 10~50W. When the frequency converter's AC side input power is frequently turned on or the contacts of the bypass contactor MC are in poor contact, the current limiting resistor R1 will burn out and an undervoltage fault will occur. There are other possibilities:
1 abnormality of energy feedback device;
2 drive board detection abnormalities;
3 If the actual undervoltage can be monitored with DCBUS in parameter U1-07.
(7) The inverter displays OV, which is the overvoltage, that is, the DCBUS voltage of the DC bus exceeds the allowable value. The specific reasons are as follows:
If the inverter drives a large inertial load, especially when it is heavily loaded and lowered, and the inverter decelerates the motor quickly, that is, during regenerative braking, the output frequency of the inverter decreases linearly, and the frequency of the load motor is higher than the output frequency of the inverter. The load motor drive is in the state of power generation, the mechanical energy is converted into electrical energy, and is absorbed by the flat wave capacitance on the DC side of the inverter. When this energy is large enough, the so-called “pump up phenomenon†occurs, and the DC side of the inverter will Trips above the maximum voltage of the DC bus.
The processing method: You can stop the inverter to run or stop the rapid deceleration method to prevent over-voltage. At this time, you should set the deceleration time parameter longer or increase the braking resistance or increase the home braking unit. Of course, in QC, it is also necessary to check the energy feedback unit (CONVERTER); it is also possible that the capacity on the grid side is insufficient, that is, the capacity of the high-side transformer is not enough, and system resonance is likely to occur.
(8) Inverter displays PGO ie speed detection open circuit, check pulse encoder and PG card.
(9) The inverter has no fault display, but it cannot run at high speed. My company once had a RTG cart driver running normally, that is, the motor can not achieve high-speed operation, after checking INVERT no fault, the parameters are set correctly, the speed input signal is normal, after the power running test, INVERT DC bus voltage is only about 450V (Normal value is 580~600V), and then measure the input side and find that there is a missing phase. The cause of the fault is a poor contact on the input side. The reason that the input phase loss is not alarming is still working in the low frequency band because the lower limit of bus voltage of the inverter is 400V. When the bus voltage drops below 400V, the inverter reports the low voltage fault of the DC bus. When the two phases are input, the DC bus voltage is 380V×1.2=452V, which is greater than 400V. When the inverter is not running, the DC voltage can reach the normal value due to the role of the flat wave capacitor, so the inverter will not report the fault. Inverter uses PWM control technology, voltage regulation and frequency modulation work in the inverter bridge, so the input phase can still work normally in the low frequency range, but due to the input voltage, output voltage is low, causing the motor torque is low, the frequency can not go , can not run at high speed.
4. Concluding remarks Yaskawa inverters are used as asynchronous motor drives on container handling cranes. Despite their high reliability, improper use or accidental events can also cause inverter damage. If you want to use a good inverter in the production process, familiar with the structure of the inverter, understand the common faults and analysis methods, it is particularly important for the personnel engaged in the equipment.
2. Yaskawa's variable frequency speed control structure and its working principle According to n=120f/p (where n=motor speed, f=motor stator-side power supply frequency, p=motor pole pair number), the number of pole pairs in the asynchronous motor is unchanged. In this case, as long as the power frequency f is changed, the speed regulation of the asynchronous motor can be realized. In the container crane, the main circuit for the asynchronous motor (voltage, frequency adjustable) contains Yaskawa Inverter, which works in the form of AC-DC-AC and provides various control signal loops for the inverter. It is called control loop, as shown in Figure 1, which includes the following parts:
(1) Rectifier bridge: UAC of three-phase alternating current is rectified into direct current UDC.
(2) Charge suppression resistor R1: According to the formula i=(UAC-UDC)/r, it can be seen that since r is a bridge rectifier equivalent resistance is small, the charging current I becomes large. In order to prevent the electrolytic capacitor from being broken down, it is necessary to install a charge suppression resistor R1 and a bypass contactor MC, thereby functioning as a current limiter.
(3) Bypass contactor MC: When the capacitor charge reaches 80%, the MC is closed and R1 is bypassed, so the element must be maintained periodically.
(4) Filter capacitor C: With energy storage function, life can reach 5~8 years. When the grid voltage drops 30%, the voltage UC at both ends of the capacitor can be maintained for 10s for the inverter to work; when the grid voltage drops 50%, The voltage UC across the capacitor can be maintained for 2s for the inverter to work.
(5) Charging indicator: When the charging voltage reaches 27V or more, the indicating lamp will be on. Therefore, after the power of the inverter is cut off, the internal components of the inverter can be repaired only when the indicating lamp is completely extinguished, to avoid electric shock.
(6) Inverter loop (bridge) master device (IGBT): Fully known as high-power bipolar insulated gate field effect hall, including gate, source, drain, characterized by voltage control device, low gate trigger power , High switching frequency, good characteristic suppression, that is, the on-state voltage drop, open leakage current are very small, and the service life can reach 20 years.
(7) A resistance-capacitance absorption loop is connected in parallel at both ends of the IGBT, which can suppress high-frequency harmonics because the motor is an inductive load and di/dt cannot be changed quickly.
(8) Current transformer CT collects the main circuit current, which is used as a current regulator ACR. To prevent damage to the asynchronous motor and the inverter when an abnormality such as overload occurs, the inverter stops operation or suppresses voltage and current values.
(9) Main control board: It is a 32-bit microprocessor that compares the external speed and torque commands with the current and voltage signals of the detection circuit to determine the output voltage and frequency of the inverter.
(10) Driver board: It is the circuit that drives the inverter main device IGBT. It is isolated from the control circuit and controls the turn-on and turn-off of the IGBT. If the IGBT is damaged, the associated driver board is generally damaged.
(11) Speed ​​detector PG: It is a pulse encoder, mounted on the output shaft of the asynchronous motor, and collecting the speed signal. It is connected to the internal PG card of the inverter and transmits the speed to the arithmetic circuit so that the motor can run according to the given command.
(12) I/F communication board: It is better to exchange the input and output signals with the inverter for human-machine exchange, including the input of various internal parameters.
3. Analysis and Handling of Common Faults of Yaskawa Inverter Yaskawa's inverters are equipped with a hand actuator on the electrical cabinet door, and display various parameter values ​​and fault codes. The analysis is based on our experience as follows:
(1) The inverter shows OC, that is, overcurrent. It has instantaneous memory function, and it is not settable by man. It is mainly used for inverter load-side short circuit, etc. When the current flowing through the inverter device reaches the rated current of 2.7 to 3 times, Instantly stop the inverter operation and cut off the power supply; the inverter output current reaches an abnormal value and the inverter will also stop running. Specific treatment can be checked one by one as follows:
1 whether the acceleration time is too short;
2 whether the torque increase parameter is too large;
3 Is the load externally short-circuited or over-weighted? For example, if there are two motor drives in the car organization, one of them may be damaged, and the other may experience over-current.
4PG detection circuit is abnormal, including PG card and pulse encoder;
5 whether the current transformer is abnormal;
6 Main power device IGBT is abnormal;
7 If there is no problem with the above, you can disconnect the output current negative inductor and DC detection point, run after reset, and there is overcurrent, it is likely that the main control board or trigger board has failed.
(2) Inverter display OL is overload, which is mainly used for the inverter output current exceeds the rated value, and continues to circulate for more than the specified time, in order to prevent damage to the inverter devices, wires, etc., to stop the inverter. Specifically divided into the following three:
1 If the current exceeds 150% of the rated current for 60s, the OL1 fault is reported, indicating that the motor is overloaded;
2 If the current exceeds the rated current for 180% for 10s, it will report OL2 fault, indicating that the inverter is overloaded;
3 When the current exceeds the rated current of 200% for 5 seconds, the OL3 fault is reported, indicating that the system is overloaded, that is, the torque protection of the steel structure.
No matter what kind of overload, it is because the GD2 (inertia) of the load is too large or is generated due to the load over the ambassador motor stalled, so that for the failure of the inverter that has been put into operation, the condition of the load must be checked; for the new The installed inverter has this type of fault, which may be caused by incorrect setting of the V/F curve or a problem with the motor parameter setting. For example, a newly installed inverter drives a variable-frequency motor with a rated parameter of 220V/50Hz, and the inverter is set to 380V/50Hz at the factory, causing magnetic saturation after the motor has run for a period of time to reduce the speed of the motor and generate heat. And overloaded.
(3) Inverter display GF is the load short circuit to ground, which has transient function, that is, the three-phase phase current deviation is greater than 50% of the rated current. The specific reasons are as follows:
1 motor insulation is not good or three-phase and phase imbalance;
2 Abnormal inverter, mainly control loop.
(4) The inverter shows OH that the inverter is overheated and can be divided into OH1 and OH2. The reasons are as follows:
1 whether the two sets of fans in the inverter cabinet are abnormal;
2 The ambient temperature is too high;
3 Frequent overloading;
4 Abnormal phenomenon such as excessive dust in the thermal detection device.
(5) The inverter displays OS, namely overspeed, hardware and software overspeed, and the set values ​​are 115% and 110% of the rated speed. At this time, check whether the PG feedback is normal.
(6) The inverter displays UV or undervoltage, that is, the DC bus voltage fault is detected. When designing the startup circuit of the inverter, a general designer selects a small current limiting resistor R1 in order to reduce the volume of the inverter, and its resistance is 10~50Ω and the power is 10~50W. When the frequency converter's AC side input power is frequently turned on or the contacts of the bypass contactor MC are in poor contact, the current limiting resistor R1 will burn out and an undervoltage fault will occur. There are other possibilities:
1 abnormality of energy feedback device;
2 drive board detection abnormalities;
3 If the actual undervoltage can be monitored with DCBUS in parameter U1-07.
(7) The inverter displays OV, which is the overvoltage, that is, the DCBUS voltage of the DC bus exceeds the allowable value. The specific reasons are as follows:
If the inverter drives a large inertial load, especially when it is heavily loaded and lowered, and the inverter decelerates the motor quickly, that is, during regenerative braking, the output frequency of the inverter decreases linearly, and the frequency of the load motor is higher than the output frequency of the inverter. The load motor drive is in the state of power generation, the mechanical energy is converted into electrical energy, and is absorbed by the flat wave capacitance on the DC side of the inverter. When this energy is large enough, the so-called “pump up phenomenon†occurs, and the DC side of the inverter will Trips above the maximum voltage of the DC bus.
The processing method: You can stop the inverter to run or stop the rapid deceleration method to prevent over-voltage. At this time, you should set the deceleration time parameter longer or increase the braking resistance or increase the home braking unit. Of course, in QC, it is also necessary to check the energy feedback unit (CONVERTER); it is also possible that the capacity on the grid side is insufficient, that is, the capacity of the high-side transformer is not enough, and system resonance is likely to occur.
(8) Inverter displays PGO ie speed detection open circuit, check pulse encoder and PG card.
(9) The inverter has no fault display, but it cannot run at high speed. My company once had a RTG cart driver running normally, that is, the motor can not achieve high-speed operation, after checking INVERT no fault, the parameters are set correctly, the speed input signal is normal, after the power running test, INVERT DC bus voltage is only about 450V (Normal value is 580~600V), and then measure the input side and find that there is a missing phase. The cause of the fault is a poor contact on the input side. The reason that the input phase loss is not alarming is still working in the low frequency band because the lower limit of bus voltage of the inverter is 400V. When the bus voltage drops below 400V, the inverter reports the low voltage fault of the DC bus. When the two phases are input, the DC bus voltage is 380V×1.2=452V, which is greater than 400V. When the inverter is not running, the DC voltage can reach the normal value due to the role of the flat wave capacitor, so the inverter will not report the fault. Inverter uses PWM control technology, voltage regulation and frequency modulation work in the inverter bridge, so the input phase can still work normally in the low frequency range, but due to the input voltage, output voltage is low, causing the motor torque is low, the frequency can not go , can not run at high speed.
4. Concluding remarks Yaskawa inverters are used as asynchronous motor drives on container handling cranes. Despite their high reliability, improper use or accidental events can also cause inverter damage. If you want to use a good inverter in the production process, familiar with the structure of the inverter, understand the common faults and analysis methods, it is particularly important for the personnel engaged in the equipment.
Electric Heater Series,Energy Efficient Heater,Small Electric Heater,Portable Electric Heater
CIH Hong Kong Ltd. , https://www.dragon-town.com