Due to incorrect use of unreasonable or the provision of the environment will be likely to cause maloperation and inverter failure, or unable to meet the expected operating results. To take precautionary measures, prior to the cause of the malfunction careful analysis appears to be particularly important.
External interference electromagnetic induction
If the inverter exist around the interference source, which will power line through radiation or invasive inverter internal caused maloperation control loop, resulting work is not normal or shutdown, even when serious damage inverter. Raising inverter own anti-jamming capability is important, but because of the installation cost constraints, taken in the external noise suppression measures to eliminate interference source appeared to be more rational and more necessary. The following measures are implemented to noise interference with the "three noes" principles of the specific methods: Inverter around all relays, the contactor coil control on the installation of the need to prevent the absorption of impulse voltage devices, such as RC absorber; shortest possible control circuit wiring distance, and make it with the main line separation; designated by shielding line loop, subject to the provisions, if a line should be used reasonable relay; inverter grounding terminal in accordance with the regulations, not the same welding , the driving force grounding mix; inverter input noise filters installed to avoid power supply into line by the introduction of interference.
Installation Environment
Inverters are electronic devices installed in its specifications in detail installation environment. In exceptional circumstances, if indeed unable to meet these requirements must be kept to adopt corresponding measures to inhibit: vibration is caused mechanical damage electronic devices the main reason for the greater impact vibration occasion should be used rubber anti-vibration measures humidity, corrosion gases and dust, and other electronic devices will cause rust, being exposed, and the formation of insulation to reduce short-circuit, as a precautionary measure, to deal with anti-corrosion and dust control board processing, and use of closed-end structure, temperature electronic devices that affect the life and reliability important factors, in particular the semiconductor devices, in accordance with the requirements of environmental conditions devices install air-conditioning or avoid direct sunlight.
In addition to the above 3:00, the regular inspection of the air filter inverter and the cooling fan is very necessary. Alpine for a special occasion, in order to prevent the temperature is too low not because of the microprocessor normal work space heater should be set up to take the necessary measures.
Power anomalies
Power frequently manifests itself in various forms vary, but roughly be divided into the following three kinds, namely lack phase, low voltage, power failures, and sometimes also their mixed form. The main reason for these anomalies is the most transmission lines due to wind, snow, caused by lightning, and sometimes because of the same within the power supply system to short-circuit and phase short circuit. The lightning season due to geographical and there is a great disparity. In addition to voltage fluctuation, some self-generating unit or power grid would frequency fluctuations, and these phenomena are sometimes repeated in a short time, in order to guarantee the normal operation of equipment, inverter power supply also raised the corresponding requirements.
If the direct vicinity of starter motor andequipment, in order to prevent such equipment when the input voltage lower, and inverter power supply system separation, reducing the mutual impact of the instantaneous power requirements will continue to run after the occasions , in addition to selecting suitable inverter prices, but also because of anticipated load motor velocity ratio. Inverter and external control circuit used blink stop compensation, when the voltage back, through the tracking speed of the motor and gun detection to prevent the acceleration of the current; of the requirements must be running the equipment, to the inverter not the installation of the automatic switching power supply devices.
Diode importation and the use of single-phase power inverter control, although lack of state can continue to work, but in the individual devices rectifier current excessive and capacitor pulse current too large, long-term operation will be if the life and inverter adversely affect the reliability should be dealt with early detection.
Struck by lightning, lightning sensors
Lightning or the impact of a lightning induced voltage is sometimes the inverter can cause damage.In addition, when the power system with a lateral vacuum circuit breaker, the opening and closing of short circuit can also have a higher impulse voltage. VCB transformer primary side disconnect, in the secondary side through the coupling of a high voltage shock peak.
To prevent over-voltage impulse voltage causing damage to the inverter usually requires the input, such as absorption and varistor device to ensure that the input voltage does not exceed the period inverter main circuit allowed by the maximum voltage. When using vacuum circuit breaker, the impact should be formed by additional RC surge absorber. If the transformer is a vacuum circuit breaker side, as in the control timing guarantees VCB before they inverter action disconnect.
Past transistor inverter mainly in the following shortcomings: easy trip, it is not easy to start, the load capacity low. The IGBT and the rapid development of the CPU, increasing the inverter internal sound self-diagnosis and fault prevention functions, substantially improve the reliability of the inverter.
If the use of vector control inverter in the "whole scope automatic torque compensation function", "starting torque inadequate", "causing changes in environmental conditions contribute decline" cause of the malfunction, will be good to overcome. The feature is the use of micro-inverter internal high-speed computer operations, the calculated time required by the current torque, rapid output voltage on the amendment and compensation to offset changes due to external conditions caused by the inverter output torque changes .
Moreover, as the inverter software development more perfect, the inverter can be pre-set various internal fault prevention measures, and failure to resolve the continued operation would remain after, for example: free parking on the process of re-starting the motor ; automatically reset the internal fault and maintain continuous operation; excessive load torque can be automatically adjusted when running curve to avoid Trip; mechanical system can detect abnormal torque.
Inverter impact on the surrounding equipment and fault prevention
The inverter installation will also have an impact on other equipment, and sometimes even lead to other equipment failures. Therefore, the impact of these factors on the analysis and study what measures should be taken very necessary.
High-order harmonic generation Power
Since almost all of the inverter using PWM control mode, this form of pulse modulation inverter operation made at the side of a high-power harmonic current and voltage waveform distortion caused the power system have a serious impact, usually adopts the following Treatment: Using the inverter transformer for power supply, power supply systems and other separation; side in the installation of inverter input filter reactor or more bridge rectifier circuits, reduce the high harmonic components, for those that are into the phase capacitor the occasions because of high harmonic current capacitive current increase will cause severe fever, must capacitance ago rods reactor to reduce the harmonic component of the reactor's electrical induction reasonable analysis, the formation of LC avoid oscillation.
Motor and high temperature operating range
As for the existing motor VVVF transformation, because of the cold motor running in the low-speed cooling capacity resulting decline in motor overheating. In addition, because the inverter output waveforms contained in the high-order harmonic generation is bound to increase the iron loss and motor copper losses, it confirmed the electrical load in the state and the scope of operations, to take the following measures: a strong cold ventilation motor raising the electrical specifications or grading; replacement variable frequency dedicated motor; limited scope of operation, avoiding low-speed zone.
Vibration, noise
Vibration is usually due to the fluctuating electrical and mechanical systems torque caused by the resonance, especially when pulsating torque and mechanical resonance exactly the same, when even more serious. Noise devices are usually divided into variable frequency noise and electrical noise, for the installation of different places should be treated differently in the measures: inverter in the debugging process, guarantee the accuracy of control under the premise of pulse should minimize torque component; confirmed Debugging mechanical Resonance, using inverter frequency shielding function, so that these resonance point exclude from the scope of the operation; As inverter main cooling fan noise electromechanical Reactor produced, low noise devices for use in motor and the inverter set reasonable between AC reactor, reducing the PWM modulation caused by the high harmonics.
High-frequency switching to a peak voltage electrical insulation negative
The inverter output voltage, which use high-frequency waves peak voltage.The impact of these high harmonic voltage will lower motor winding insulation strength, particularly in the PWM-controlled inverter more obvious, we should adopt the following measures: minimize the inverter to the motor wiring distance; by blocking diodes Surge voltage absorption device, the output voltage of the inverter to handle the PWM inverter should try to increase in the electrical input side filter.