Analysis on the maintenance of abbacs600 multi dri

Analysis of ABB ACS600 multi drive frequency converter maintenance

1 introduction

abb ACS600 series frequency converters have been available for more than ten years, and are widely used in power generation, chemical industry, papermaking, metallurgy, transportation and other industries in China. This series of frequency converters has won the recognition of users with its stable performance, rich options and extended functions, flexible programming environment and good torque characteristics. In particular, the ACS600 multi drive frequency converter has excellent performance in energy saving due to its energy feedback function, so the application effect on the elevator is very ideal. Although this series of frequency converters has been out of the market for many years, it is still of great significance to explore its maintenance technology and methods because of its huge stock and will continue to be used for a long time in the future

the author has been engaged in frequency converter maintenance for more than ten years and has a deep understanding of ACS600 series frequency converters. Our company has 14 gantry cranes, which are mainly engaged in the ship loading and unloading of bulk cargo at the wharf. The drive system adopts ACS600 multi drive frequency converter, which has been used for nearly ten years and is now in good operation. Generally speaking, the failure rate of the frequency converter system is still low, but due to the influence of the working environment (mainly temperature, vibration, dust and other factors), the internal components of the frequency converter are still damaged from time to time. The author summarizes the maintenance experience and skills in practical work over the years, and hopes to exchange and discuss with the majority of peers

Figure 1 Composition of ACS600 multi drive frequency converter system

2 working principle and internal structure of ACS600 multi drive frequency converter

acs600 multi drive frequency converter system is mainly composed of auxiliary control unit (ACU), incoming line unit (ICU), filter unit (FIU), power supply unit (ISU) and several inverters, as shown in Figure 1. The auxiliary control unit, incoming line unit and filter unit are mainly composed of circuit breakers, contactors, collectors, reactors and other components. The power supply unit and inverter are mainly composed of control boards, power modules and other components. Here we mainly discuss the repair of internal components damage of power supply unit and inverter. When the inverter system is working, the power supply unit rectifies the three-phase AC into DC and sends it to each inverter through the DC bus. Both the power supply unit and the inverter can realize four quadrant operation. The AC under the power generation state of the motor can be shared by the inverter through the DC bus or sent back through the power supply unit

the hardware structure of the power supply unit is basically the same as that of the inverter, as shown in Figure 2. It is mainly composed of power supply board (nPow), main circuit interface board (Nint), gate drive board (n the fatigue life testing machine of elastic components produced by Shandong Sida high tech is mainly used for fatigue life testing GDR of various bellows, fiberglass tubes, elastic components, etc.) and IGBT power modules. When three power modules are used in parallel in the power supply unit, a matching board (nxpp) is required, and a Misstart prohibition board (NGPs) is also used in the inverter, In addition to the above control boards and power components, there are also capacitors, current transformers, discharge resistors, fans and other components in the module. There is a control unit (ndcu) outside the module, which is composed of two circuit boards: control board (NAMC) and i/o interface board (NIOC). The control board is the control core of the power supply unit and inverter. The application software and parameter group of the frequency converter are stored here. The i/o interface board is responsible for the collection and output of each i/o signal, and can be connected to the cdp312 control panel at the same time. When the power supply unit or inverter works, the power board provides 24V and 15V power supplies for internal use. The main circuit interface board collects various internal signals, receives the processing results output from the control unit, and provides signals to the gate drive board. The gate drive board receives the signal from the main circuit interface board and provides the signal to drive the IGBT gate level action. Then the IGBT power module inverts the DC into AC through the on-off switch, or rectifies the AC into DC, driving the motor or feeding back electric energy. The control boards and components inside the module are connected by connectors, and the control unit is connected by optical fiber with inverter module, upper computer and various options (encoder adapter, communication adapter, etc.). Understanding the function and connection mode of the module and control unit is the basis of the internal troubleshooting of the frequency converter. On this basis, we should further master the function of the connecting terminal signal of each board and the measurement method of whether the components are normal or not. In this way, it is much easier to analyze, find and repair faults

3 common fault analysis of ACS600 multi drive frequency converter

3.1 power board fault

(1) fault phenomenon

drive motor does not act, cdp312 control panel does not display

(2) fault analysis and treatment

cdp312 control panel is connected to the NIOC board of the control unit. First, check the power supply of the control unit. The power supply of the control unit is 24V DC power supply, which can be powered by external DC power supply or internal power board. In this example, the power is supplied by the power board. The function of the power board is to convert the DC power (about 560V) on the DC bus into two groups of 24V and 15V power supplies for the main circuit interface board and other components. First of all, it is necessary to determine whether the DC bus voltage is normal. When it is normal, the on-board green LED light (V15) is on, which can be confirmed by measuring the pin 1 and pin 4 of the plug-in terminal X31 of the power board. If there is no voltage, the quick fuse on the DC bus should be checked upward. Generally, the fusing multi solenoid directional valve of the quick fuse is always accompanied by the damage of the power module in the energized state, so once the fuse is found to be fused, the power module must be checked first, Do not replace the fuse blindly. Under the condition that the DC bus voltage measurement is normal, when the on-board v15led light is not on, the on-board fuse F1 is more likely to blow, and its quality can be detected with a multimeter. The main function of the on-board fuse F1 is to protect the DC input voltage. According to the maintenance of several similar faults, its fusing is usually caused by the instantaneous voltage fluctuation of the DC bus. It can be replaced directly when it is determined that the on-board components have no appearance damage. When the input side of the power board is normal, measure the output side. The plug-in terminal X34 is the DC 24V power supply to the control unit. Measure pin 1 and pin 2 to confirm. If there is no voltage, it indicates that the switching power supply part of the power board is damaged and needs to be replaced. The plug-in terminal X32 of the power board is used to supply the main circuit interface board as the gate level driving voltage. Normally, use a multimeter to measure (the probe is connected to 4 PINS), 2 pins -24v, 3 pins -15v, 5 pins +15v, 6 pins +24v. When the power module cannot be triggered or other difficult faults occur, focus on detecting this place. In this case, it is detected that the switching power supply part of the power board is damaged, and the fault is eliminated after replacing the new board

Figure 2 internal structure of inverter module

3.2 control unit fault

(1) fault phenomenon

drive motor does not act, cdp312 control panel does not display

(2) fault analysis and treatment

first eliminate the DC 24V power supply fault. In this example, the input 24V power supply of the control unit is normal, but the power supply normal indicator light (V4) on the NAMC board of the control unit is not on, which indicates that there is component damage inside the control unit. Generally, the components of the control board are damaged, and the user cannot repair them by himself. He can only replace the control unit or NAMC board. However, through the study of the NAMC and NIOC boards in the control unit, the author found that there is a patch fuse (F1) in the power part of the NAMC board. Among the previously damaged control units, the damage rate of this fuse is more than 50%, indicating that this is a weak link in the ACS600 inverter control unit. There is no abnormal appearance when the insurance is damaged, which can be measured and detected by a multimeter. Because the fuse is a very small patch element and cannot be replaced directly, the author adopts the method of leading out the signal lines at both ends of the fuse and connecting the glass fuse tube in series outside to repair the damaged control unit, and the effect is good. Friends who have encountered similar problems before can check the fault control unit that has been replaced in the past to see if it is the same problem. If this method can be used to repair it, the components worth 10000 yuan will be reborn

3.3 IGBT power module fault

(1) fault phenomenon

the drive motor does not act, and the frequency converter immediately reports the "PPCC link" fault after receiving the operation signal

(2) fault analysis and treatment

"PPCC link" according to the tips in the inverter manual, there is a problem with the optical fiber connection between the Nint board and the NAMC board. But the actual situation is not like this. In fact, the probability of optical fiber connection failure is very low. The appearance of "PPCC link" is often accompanied by the damage of IGBT power module, which is the experience of the author in the maintenance of ACS600 inverter for many years. When overhauling, first eliminate the optical fiber connection fault through detection. Then detect the IGBT power module (each IGBT is composed of three independent modules, which can operate independently or in parallel). Before the measurement, the IGBT should disconnect the motor connecting cable and DC busbar on the AC side, otherwise it will produce wrong measurement values caused by capacitance and motor winding. Use the diode block of the multimeter to measure the AC side terminal (P) and DC positive (+) and negative (-) of each module of BT, which is a legal quarantine object. When it is normal, the black probe is connected to P and the red probe is connected to - - and the display is 0.34v, which is cut off when the probes are adjusted; The black probe is connected with +, and the red probe is connected with P, and the display is 0.34v. When the probes are adjusted, it is cut off. In this example, the short circuit between + and P of the module of one phase of IGBT indicates that a freewheeling diode of this phase has been broken down and the IGBT power module needs to be replaced. According to the requirements of the frequency converter manual, when replacing IGBT, it is necessary to replace the main circuit interface board and the gate drive board at the same time. This shows that the damage of most IGBT power modules is caused by the wrong trigger signal provided by the damaged main circuit interface board and gate drive board. After years of exploring the phenomenon and causes of IGBT power module damage, the author found that the damage of IGBT can be divided into two categories: one is the explosion of the power module as a whole, and the other is the single-phase breakdown of the aforementioned module. The former is caused by the damage of the main circuit interface board or gate drive board, and the latter is mainly caused by the transient voltage and current fluctuations in the line, In this case, it is not necessary to replace the main circuit interface board and gate drive board, so as to reduce the maintenance cost

3.4 capacitor fault

(1) fault phenomenon

the drive motor has no action, the cdp312 control panel has no display, and the DC fuse is fused

(2) fault analysis and treatment

DC fuse is blown, indicating that there is a short-circuit point in the line. First, focus on the troubleshooting of IGBT power module. In this case, the IGBT module is normal after measurement, and no short-circuit point is found in the circuit measurement, and no burning trace is found in the circuit, control boards and components. The static measurement is normal, and the fault phenomenon shows that there is a short-circuit point, which indicates that the characteristics of some components have changed after the voltage is applied. The capacitive components are the most likely to happen. At this time, a simple method can be used to verify. Connect the DC bus directly to the capacitor bank with wires, connect a 660v10a fast fuse in series on the wires, and then power on for test. In this example, when the DC bus is powered on, followed by a clear "bang" sound, the fast fuse is blown, which confirms that there is a capacitor breakdown and discharge. After careful inspection of the capacitor, it was found that there was a discharge hole with a large grain of rice on the outer skin of a capacitor. After replacement, it failed