Frequency Converter Speed Control, Overload Protection, Faults, Communication, & IGBT! Comprehensive Solutions to Complex Issues
Answer: The IGBT circuit is the part responsible for the power output of the frequency converter. IGBT is the basic power component of the inverter unit and the active rectifier unit. IGBT is the core device of the frequency converter, and its function is to convert direct current (DC) into alternating current (AC) for use by motors.
Answer:
Openness and interoperability
Low cost
Simple configuration
Access to more information and diagnostic status
Answer: PID control belongs to closed-loop control, which refers to feeding back the detection signal of the controlled variable (i.e., the actual value measured by a sensor) to the frequency converter and comparing it with the target signal of the controlled variable to determine whether the predetermined control target has been achieved. If not, adjustments are made based on the difference between the two until the predetermined control target is reached.
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Predetermined Input
When using the PID function in a frequency converter, the feedback signal measured by the sensor is directly connected to the predetermined signal terminal, and the "target signal" is set via the keyboard.
Independent Input
Some frequency converters are specifically equipped with independent feedback signal input terminals. Some converters also provide power for sensors, such as the +24V, VPF, and GND terminals of the Senlan BT12S series frequency converter. The target value for this type of converter can be set via the keyboard or input through a predetermined input terminal."
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Preset values for PID function
Setting the target value
Setting the variable target value
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Preset logical relationships
Proportional gain and integral time
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Input of switching command signals
Input of analog numerical signals
RS-485 communication method
Answer: The insulation resistance of the control circuit in a frequency converter should be measured using the high resistance range of a multimeter. A measurement value above 1MΩ is considered normal. It is crucial to note that a megohmmeter must not be used to test the insulation resistance of the control circuit in a frequency converter, as it may damage the frequency converter.
Answer: Overload protection refers to the mechanism that stops the operation of a frequency converter when its output current exceeds the rated value and continues to flow for more than the specified time, in order to prevent overheating and damage to the frequency converter components, connecting wires between the frequency converter and the motor, and the motor itself. Overload protection requires an inverse time characteristic, and is usually implemented using a thermal relay or electronic thermal protection (using electronic circuits). Overload in a variable frequency drive system occurs due to excessive GD² (inertia) of the load or excessive load causing the motor to stall. The overload fault in a variable frequency drive system manifests as the motor being able to run, but with an operating current exceeding the rated value, although the excess is not significant enough to cause a large inrush current that triggers the overcurrent protection.
Answer: 1) Damage to the current and voltage detection channels of the main circuit interface board can also cause overcurrent. The causes of circuit board damage include poor environmental conditions, with conductive solid particles attaching to the circuit board causing electrostatic damage, or corrosive gases corroding the circuits. The zero potential of the circuit board is connected to the housing, which is connected to the protective earth. The ground potential on the protective earth can affect the performance of the circuits on the circuit board. In severe cases, an increase in the potential at the zero potential point of the circuit board can also cause damage to the circuit board.
Loose or insecure connection plugs. For example, poor contact in the current or voltage feedback signal lines can cause intermittent overcurrent faults.
Answer: The main circuit mainly consists of a rectifier circuit, current limiting circuit, filter circuit, braking circuit, and inverter circuit.
Answer: SCI communication refers to the Modbus RTU communication protocol.
Answer: It means one stop bit, eight data bits, and two stop bits, with no parity, using the Modbus RTU communication protocol.
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1) Overcurrent fault
2) Overvoltage fault
3) Undervoltage fault
4) Overload fault
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1) Set the frequency converter parameters according to the manual.
2) Write the PLC program based on the manual parameters.
3) Connect the communication cable and refer to the wiring diagram in the manual.
Answer: A three-phase asynchronous motor consists of a stator and a rotor, both of which have iron cores and windings.
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1) Given frequency
Also known as the set frequency, it is the frequency command from the external control to the frequency converter output.
Output frequency
The output frequency is the actual frequency output by the frequency converter.
Answer: They can withstand sufficient voltage and current, allow frequent switching on and off for a long time, have a small drive circuit current, and consume very little power.
Answer: DC bus voltage.
Answer: Multiply the frequency converter's output speed by 16384 and divide by the reference speed P2000.
Answer: The IGBT will be immediately damaged upon starting the frequency converter.
Answer: A three-phase asynchronous motor or a 220V motor.
Answer: It converts AC power to DC power.
Answer: The output voltage increases proportionally with the frequency.
Answer: The output voltage remains constant, and the motor's output effective torque decreases.
Answer: Preset time deceleration stop, free stop, and DC brake stop.
Answer: A centrifuge has a large rotational inertia and requires a large acceleration torque. Moreover, the acceleration time can take several minutes. Therefore, to prevent the overload protection of the frequency converter from activating during acceleration, a frequency converter should be selected such that the motor current during acceleration is below the rated current of the frequency converter.
Answer: A high-voltage, high-capacity AC asynchronous motor requires a high-voltage frequency converter. The frequency converter manufacturer will require relevant information from the user.
Answer: GND is ground, and COM is 0V. The COM terminal can be connected to either positive or negative.