Share three wiring methods for frequency converters, with pictures and text explanations


Release time:

2023-04-19

Frequency converters(VFD) is a power control equipment that applies frequency conversion technology and microelectronics technology to control AC motors by changing the frequency of the motor working power supply. The frequency converter is mainly composed of rectification (AC to DC), filtering, inverter (DC to AC), brake unit, drive unit, detection unit, microprocessor unit, etc. The inverter relies on the internal IGBT to adjust the voltage and frequency of the output power supply, according to the electricity to achieve the purpose of energy saving and speed regulation, in addition, the inverter has many protection functions, such as overcurrent, overvoltage, overload protection and so on. How is the frequency converter wired? This is a big problem that many people will encounter, let's use illustrations to teach you to quickly master the simple inverter wiring method.

Frequency converters(VFD) is a power control equipment that applies frequency conversion technology and microelectronics technology to control AC motors by changing the frequency of the motor working power supply. The frequency converter is mainly composed of rectification (AC to DC), filtering, inverter (DC to AC), brake unit, drive unit, detection unit, microprocessor unit, etc. The inverter relies on the internal IGBT to adjust the voltage and frequency of the output power supply, according to the electricity to achieve the purpose of energy saving and speed regulation, in addition, the inverter has many protection functions, such as overcurrent, overvoltage, overload protection and so on. How is the frequency converter wired? This is a big problem that many people will encounter, let's use illustrations to teach you to quickly master the simple inverter wiring method.

The working principle of the frequency converter: the main circuit is to provide the asynchronous motor with voltage regulation and frequency regulation power supply of the power conversion part, the main circuit of the frequency converter can be roughly divided into two categories: the voltage type is the DC conversion of the voltage source into AC frequency converter, the filter of the DC circuit is capacitor. The current type is a frequency converter that converts the DC of the current source into AC, and its DC loop filtering is inductor. It consists of three parts: a "rectifier" that converts power frequency power into DC power, a "flat wave loop" that absorbs voltage pulsations generated by the converter and inverter, and an "inverter" that converts DC power into AC power.

The wiring method of the frequency converter is as follows:
1. Wiring of the main circuit

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3) The operation and stop operation of the inverter should not be carried out by the on-off of the main circuit. Operation is done with the RUN and STOP keys on the control panel or with the control circuit terminal FWD (REV).
4) The output terminal of the inverter (U, V, W) is best connected to the three-phase motor by a thermal relay, and when the direction of rotation is inconsistent with the setting direction, any two phases of the three phases of U, V and W should be exchanged.
5) The output terminal of the inverter should not be connected to the power capacitor or surge absorber.
6) Starting from the need for safety and noise reduction, it must be grounded to prevent leakage and interference from intruding or radiating out. According to the technical standards of electrical equipment, the grounding resistance should be less than or equal to the value specified in the national standard, and the special grounding terminal PE of the inverter should be connected to a thicker short wire. When the frequency converter and other equipment, or multiple frequency converters are grounded together, each equipment should be connected to the ground separately, and it is not allowed to connect the ground end of one device and the ground end of another before grounding.
2. Control circuit terminals
1) When entering with a contact, use a contact with high contact reliability.
2) When leaving the factory, the FWD-CM is connected with a short circuit piece. After powering on, just press the RUN key on the touch panel to run forward, and press the STOP key to stop running (in the touch panel operation mode).
3) When leaving the factory, the short circuit piece has been connected between the external alarm input terminal THR-CM, and the short circuit piece should be removed when using it, and the abnormal contact of the external device should be connected in series. If this contact is not available, do not remove the short-circuit tab.
4) The analog frequency setting terminal (13, 12, 11, C1) is a terminal that connects analog voltage, current, and frequency setter (potentiometer) input from the outside, and when setting contacts on this circuit, it is necessary to use pairing contacts of small signals.
5) The contactors, electromagnetic relays and other types of electromagnet coils in the frequency conversion speed regulation system have large inductance, which will produce a high induced electromotive force at the moment of connection and disconnection, and a high peak surge voltage will be formed in the circuit, affecting the normal operation of the frequency converter. It can be controlled by an absorption circuit. When the open-collector output terminal is connected to a control relay, surge absorbing diodes can be connected across the excitation coil, as shown.

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4) The grounding cable should use a thick wire diameter as much as possible, which must be equal to or greater than the specified standard, and the grounding point should be as close to the frequency converter as possible, and the shorter the grounding wire, the better.
Inverter wiring attention
1. The inverter itself has strong electromagnetic interference, which will interfere with the work of some equipment, so we can add a cable sleeve to the output cable of the inverter.

2. The control line in the inverter or control cabinet is at least 100mm away from the power cable, etc.

3. When purchasing a frequency converter, there will be a frequency converter manual. If not, you can download it from the official website of the brand you purchased. The content above the inverter manual is quite detailed, including product introduction, working principle, installation and commissioning, etc.

AnhuiDerun ElectricTechnology Co., Ltd. as a professional manufacturer of high and low voltage switchgear, the inverter cabinet is one of the switchgear produced by our company, so it is sure that the inverter is well connected.