VFD Single-phase 220V Input to three-phase 380V Output inverter

Single-phase 220V to three-phase 380V inverter adopts AC-DC-AC circuit structure and uses SPWM modulation control technology to convert ordinary single-phase 220V to industrial three-phase 380V. It is suitable for three-phase asynchronous motors with an output phase angle of 120 °, which fully meets the motor use standards and is suitable for various types of motor loads. The single-phase power transformer three-phase power inverter solves the inconvenience caused by the three-phase power limitation in some areas, and also solves the needs of users who cannot apply for three-phase power due to site constraints.

3.1 Technical characteristics:

· 220V input for ordinary city power, eliminating the tedious procedures of applying for three-phase power, various labor costs, and various hidden costs

· The output uses industrial three-phase power, but it is charged according to civilian single-phase power, which is economical.

· The core components are imported devices, with stable performance and long service life.

· Safe and reliable, the input single-phase power is completely electrically isolated from the output three-phase power

· Wide input voltage range design to adapt to the working environment where the mains voltage is low in all regions

Complete output protection function, with multiple protections such as over-voltage, overload, over-temperature, short-circuit, over-current, etc.

Fourth, the inverter installation environment requirements

4.1 Electrical use conditions Prevent electromagnetic interference. Due to the rectification and frequency conversion of the inverter, a lot of interference electromagnetic waves are generated around the inverter. These high-frequency electromagnetic waves have some interference with nearby instruments and instruments. Therefore, the instrument and electronic system in the cabinet should use metal shells to shield the inverter from interference with the instrument. All components should be reliably grounded. In addition, the connection between electrical components, instruments and meters should be shielded control cables, and the shielding layer should be grounded. If the electromagnetic interference is not handled properly, the entire system will often be inoperable and the control unit will malfunction or be damaged.

4.2 Ambient temperature: The ambient temperature of the inverter refers to the temperature near the section of the inverter. Because the inverter is mainly composed of high-power power electronic equipment that is susceptible to temperature, the life and reliability of the inverter depend on the temperature to a large extent, generally -10 ℃ ~ +40 ℃. In addition, the heat dissipation of the inverter itself and the extreme conditions that may occur in the surrounding environment need to be considered. Generally, there is a certain margin for the temperature.

4.3 Ambient humidity: The relative humidity requirement of the inverter to its surrounding environment is not more than 90% (no condensation on the surface).

Vibration and shock: During the installation and operation of the inverter, care must be taken to avoid vibration and shock. To avoid loose solder joints and parts of the internal components of the inverter, causing serious electrical faults and even short circuits. Therefore, it is generally required that the vibration acceleration of the installation site is limited to 0.6 g or less, and special places can be added with anti-vibration measures such as anti-vibration rubber.

4.4 Installation place: The maximum allowable output current and voltage of the inverter are affected by its heat dissipation capacity. When the altitude exceeds 1000 m, the inverter’s cooling capacity will decrease. Therefore, the inverter is generally required to be installed below 1000 m above sea level. Abnormal environmental conditions, such as exposure to excessive dust, altitude> 1000 m, etc., require special selection Structural or protective parts.

4.5 Inverter storage: In practice, the inverter is generally installed on the field equipment or installed nearby. If the site environment is poor (high temperature, humidity, dust), the inverter can be placed in the power supply under the conditions allowed by the operation. Control room. When the operator is placed on site, for the safety of the inverter, the general ambient temperature should be -10 ℃ ~ + 50 ℃. When it is used in the open air, such as oil fields, offshore oil wells, mines, etc., the winter temperature should be lower than -10 ° C, you can use an electric heater to heat it, and place the inverter in an external box; in summer, the ventilation can be enhanced when the temperature is above + 50 ° C, Insulation coating is applied to the outside of the box to reduce radiation and heat conduction. According to the actual situation on the scene, according to local conditions, artificially try to improve the environment and ensure safety. For harsh environments such as dust and fiber on site, the inverter should be placed in a box, and a filter screen should be installed at the air inlet and outlet to periodically clean and strengthen maintenance.

6.2 Notes:

· Boost inverter is a capacitor booster. For the load, it is used for light-loaded sites under 22kw. In the selection, the light-duty motor is selected by a large-level inverter, and the heavy-duty field is selected by a large-level inverter. Inverter.

· Boost inverter can only be used in three-phase asynchronous motors, not as a power source.

· Boost inverter is not suitable for the site that needs quick start and stop, and occasions with potential energy load

VFD Single-phase 220V to three-phase 380V boost inverter

First, the market demand

Due to national policies and regional restrictions, many regions will now withdraw three-phase 380V industrial power, and the cumbersome procedures for applying three-phase electricity in areas without three-phase electricity, various labor costs, and various hidden costs, etc., lead to some The region cannot use industrial 380V electricity, and general industrial equipment, such as motors, are mostly three-phase 380V. In the absence of three-phase electricity, it can not be operated. Only a way to convert single-phase 220V into three-phase 380V, but Many single-phase 220V electric three-phase 380V equipment on the market are expensive and outrageous, which makes many users in need have to be discouraged. The original machine can only be temporarily placed or placed in other places with industrial power.

Now our company has introduced a single-phase 220V input to three-phase 380V output inverter, which can drive the three-phase asynchronous motor to start up smoothly and carry out stepless speed regulation. Input power only needs single-phase 220V, output three-phase 380V, and most users can accept the price. It is about 1/10 of the price of the booster on the market. It is small in size and powerful in function. 0-650Hz can be adjusted freely. Solve the embarrassing situation that industrial equipment does not have three-phase electricity.

Second, the principle and characteristics of 220V to 380V inverter

The principle of the frequency converter is to apply the principle of frequency conversion technology and microelectronic technology. The power control equipment of the AC motor is controlled by changing the frequency of the working power of the motor, and the power frequency alternating current with constant voltage and frequency is converted into voltage or frequency. The device of alternating current is called “inverter”.

The waveform outputted by the inverter is an analog sine wave, which is mainly used for three-phase asynchronous motor speed regulation, also called frequency converter. The frequency converter is mainly composed of rectification (AC to DC), filtering, inverter (DC to AC), braking unit, drive unit, and detection unit micro processing unit. The frequency converter mainly adopts the AC-DC-AC mode (VVVF frequency conversion or vector control frequency conversion). First, the power frequency AC power supply is converted into a DC power source through a rectifier, and then the DC power source is converted into an AC power source whose frequency and voltage can be controlled to supply. electric motor.

The 220V to 380V inverter converts the power frequency AC 220V power supply into a DC power supply through a rectifier (double voltage rectification), and then converts the DC power into a three-phase 380V AC power source whose frequency and voltage can be controlled to supply the motor.

2.1 inverter function

1. It can reduce the impact on the power grid, and it will not cause the problem of excessive peak-to-valley difference.

2. The acceleration function can be controlled to smoothly accelerate according to the needs of the user;

3. The motor and equipment stop mode can be controlled, making the whole equipment and system more secure and the life expectancy will increase accordingly;

4. Control the starting current of the motor, fully reduce the starting current, and reduce the maintenance cost of the motor;

5. It can reduce the wear of mechanical transmission components, thereby reducing procurement costs and improving system stability.

6. Reduced motor starting current, providing a more reliable variable voltage and frequency.

7. Effectively reduce reactive power loss and increase the active power of the grid

8. Optimize the process and change rapidly according to the process. It can also realize the speed change through remote control PLC or other controllers.

What is the scope of use of the inverter?

The frequency converter is a kind of speed control device. Where it is useful to adjust the speed of the motor, especially the speed of the asynchronous motor, the inverter will be used. At present, it is mainly used on industrial equipment because the motor is the heart of the industry. The three-phase asynchronous motor occupies the majority of the proportion, so the inverter is used the most, and with the improvement of life, the inverter also uses a lot of life.

1. On the fan, it can be used to control the air volume, such as boiler drum induced draft fan, factory fan, central air conditioning fresh air fan and exhaust fan, which can adjust the wind speed according to the combustion condition or other requirements, and control the supply air volume. The role of the valve size.

2, the pump industry, industrial recycling water, life inverter constant pressure water supply, sewage treatment, the same reason some chemical liquid raw materials will also be used in the transmission of the frequency converter, these are also used to control some liquid flow or pressure use. As with the fan control, the accuracy required for the inverter is not high, and a dedicated fan-pump type inverter is used, which is relatively cheap and can meet the requirements.

3. Some transmission fields are used to control the transmission, such as conveyor belts and transmission rollers. It is necessary to control the transmission speed of materials to synchronize the overall production line. In this case, a general-purpose inverter can be used.

4, mixing, mixing, grinding, crushing, extrusion, throwing and some rolling occasions, need to let the equipment “bite” each other, so that the material is fully mixed, this process also needs control process, need to use the frequency converter to complete General general type can also meet the requirements.

5, hanging, hoisting, rewinding and other occasions, the inverter needs to achieve a certain synchronization and tension control, the accuracy requirements are relatively high, you need to use vector inverter or direct torque control type inverter.

6, air conditioning compressors and air compressors and other occasions, the current use of synchronous motors, control algorithms and asynchronous reality are similar, but also variable frequency speed control, just because of the motor, the efficiency is relatively high.

7. Automobile and motorcycle industry, from trains to electric vehicles, three-wheel electric vehicles and two-wheeled battery vehicles, vehicles, currently have inverters in use.

8. In the processing industry, robots, etc., the inverter can be used as a spindle or an important rotary table motor. If the servo is also regarded as a special inverter, it is used by each axis.

What is the meaning of torque, torque and torque that the inverter often says?

Torque in physics refers to the tendency of a force to cause an object to rotate about a rotating axis or fulcrum. Torque, the physical quantity of force acting on an object, can be divided into the moment of the force versus the axis and the moment of the force versus the point. The rotational torque is also called torque or torque.


Where L is the distance vector from the axis of rotation to the point of force, and F is the vector force. The moment is also a vector, and the unit of torque is Newton-meter.

What is the meaning of torque, torque and torque that the inverter often says?

The concept of torque can be seen everywhere in our daily lives, from the seesaws I played as a child, to the famous quote of Archimedes – “Give me a fulcrum, I will shake the whole earth”, which all reflect the meaning of the moment. Similarly, torque is ubiquitous in cars, but through a series of rotations of the drive shaft, the torque here is called torque. The amount of torque directly affects the power output efficiency, energy consumption, and even operating life and safety performance.

What is the meaning of torque, torque and torque that the inverter often says?
The difference between torque and torque:
The range covered by the two is different. The range of the torque is wider. The result of multiplying the force by the force arm can be called the moment, but the torque generally refers to the torque received by the rotating object. For example, when a wheel rotates, the product of ground friction and wheel radius is generally referred to as torque, but is also a type of torque. The use of a bottle to open a beer bottle is generally called torque, but can not be said to be torque.
The difference between torque and torque:
The couple or torque that causes the machine component to rotate (including the tendency to rotate) is called the rotational torque, referred to as torque. Any component under the action of torque must have some degree of torsional deformation (which may include elastic deformation and plastic deformation). Therefore, it is customary to often refer to the turning moment as the torsional moment, referred to as the torque. Both can be mixed in any field, but torque is more common in engineering.

Torque, torque and torque are actually the same in the motor. Generally, in the same article or the same book, the above three nouns use only one, and it is rare to see two or more at the same time. Although the three words are used in different occasions, in the motor, it refers to the driving “moment” generated by the rotor winding in the motor that can be used to drive the mechanical load. The so-called “moment” refers to the force and the fulcrum and force. The product of the distance perpendicular to the direction.

Regular maintenance and inspection of the inverter

1. Inverter maintenance check precautions

When performing maintenance inspection, be sure to cut off the power input to the inverter (R.S.T);
After confirming that the inverter power is cut off and the display disappears, wait until the internal high voltage indicator is off before performing maintenance and inspection.
During the inspection process, the internal power supply and wire, cable should not be pulled up and mismatched, otherwise the inverter will not work or be damaged.
Accessories such as screws should not be left inside the inverter during installation to avoid short circuit on the board.
Keep the inverter clean after installation to avoid dust, oil mist and moisture intrusion.

2, the inverter regularly check the project

The power supply voltage is confirmed to meet the voltage required by the inverter; (pay special attention to whether the power cord and motor are damaged.) Is the wiring terminal and connector loose? (Whether there is a broken wire in the power cord and terminal)
Whether there is dust inside the inverter, output current, output frequency (the difference between the measurement results is not too large)
Check if the surrounding temperature is between -5 °C and 40 °C, and whether the installation environment is well ventilated;
Humidity: maintained below 90%; (no phenomenon of water droplets)
Whether there is abnormal sound or abnormal vibration during operation; (The inverter cannot be placed in a place with high vibration)
Please do the cleaning work regularly.

3. Replacement of spare parts

The frequency converter is composed of various components, some of which will gradually reduce and age after long-term operation. This is also the main reason for the failure of the inverter. In order to ensure the long-term normal operation of the equipment, the following components should be replaced regularly:

(1) Cooling fan

The power module of the frequency converter is the most heat-generating device, and the heat generated by its continuous operation must be discharged in time. The life of the general fan is about 10kh~40kh. According to the continuous operation of the inverter, it is necessary to replace the fan for 2~3 years. The direct cooling fan has two lines and three lines. One of the two-line fans is positive and the other line is negative. Do not connect incorrectly when replacing. The three-wire fan is not only connected. There is also a detection line outside the negative pole. Please pay attention when replacing it, otherwise it will cause the inverter to overheat alarm. The AC fan is generally 220V, 380V, and the voltage level should not be mistaken when replacing.

(2) Filter capacitor

Intermediate DC loop filter capacitor: also known as electrolytic capacitor, its main function is to smooth the DC voltage, absorb the low frequency harmonics in DC, and the heat generated by its continuous operation plus the heat generated by the inverter itself will accelerate the drying of the electrolyte. Directly affect the size of its capacity. Under normal circumstances, the life of the capacitor is about 5 years. It is recommended to check the capacitance capacity once a year regularly. Generally, if the capacity is reduced by more than 20%, a new filter capacitor should be replaced.

4 regular maintenance

Regular dust removal check whether the fan air inlet is blocked, and clean the air filter cooling air duct and internal dust every month.

Regular inspections should be carried out once a year: check whether the screws, bolts and plug-ins are loose, whether the grounding and phase-to-phase resistance of the input and output reactors are short-circuited, and should be greater than several tens of megaohms. Whether the conductor and the insulator are corroded, if necessary, wipe it with alcohol in time. Measure the smoothness of the voltage of each circuit output of the switching power supply, such as: 5V, 12V, 15V, 24V and other voltages. Whether the contact of the contactor has a fire mark, it is necessary to replace the new contactor of the same model or larger than the original capacity; confirm the correctness of the control voltage, perform the sequence protection action test; confirm that the protection display circuit is not abnormal; confirm that the inverter is The balance of the output voltage when operating alone.

Carefully do the daily maintenance and repair of the inverter, the main contents include:

(1) Regularly dedusting the inverter, focusing on the rectifier cabinet, the inverter cabinet and the control cabinet. If necessary, the rectifier module, the inverter module and the circuit board in the control cabinet can be removed for dust removal. Whether the air inlet and upper air outlet of the inverter are dusty or blocked due to excessive dust accumulation. The frequency converter has a large amount of ventilation due to its own heat dissipation. Therefore, after a certain period of operation, the surface area dust is very serious and must be cleaned regularly.

(2) Open the front door of the inverter, disassemble the rear door, carefully check whether the AC and DC busbars are deformed, corroded, oxidized, whether the screws at the joints of the busbars are loose, and whether the screws at the fixed points are loose or not. Whether the insulating sheet or the insulating column for fixing has aging cracking or deformation, if it should be replaced in time, re-tighten, and the busbar that has been deformed must be corrected and reinstalled.

(3) After dust removal of circuit boards and busbars, carry out the necessary anti-corrosion treatment, apply insulating varnish, and remove the burrs of the busbars that have appeared partial discharge and arcing before processing. For insulation boards that have been insulated and penetrated, the damaged parts shall be removed, and the insulation boards of the corresponding insulation grade shall be insulated in the vicinity of their damage, and the insulation shall be tightened and tested and deemed to be qualified before being put into use.

(4) Whether the fan running and rotating in the rectifier cabinet and the inverter cabinet are normal. When the machine is stopped, turn it by hand to observe whether the bearing has stuck or noise, and replace the bearing or repair if necessary.

(5) Thoroughly inspect the input, rectification and inverter, and DC input fast-melting, and find that the burning is replaced in time.

(6) Whether the capacitor in the intermediate DC circuit has leakage, whether the casing is expanded, bubbling or deformed, whether the safety valve is broken, and the capacitor capacity, leakage current, and withstand voltage can be tested under conditions, which does not meet the requirements. The capacitors are replaced. For new capacitors or unused capacitors that have been unused for a long time, they must be passivated before replacement. The usage period of the filter capacitor is generally 5 years. If the usage time is more than 5 years, the capacitance capacity, leakage current, and withstand voltage are obviously deviated from the detection standard, and should be replaced partially or completely as appropriate.

(7) Conduct electrical inspection on the rectifier and inverter part diodes and GTO multimeter, measure the forward and reverse resistance values, and carefully record in the prepared form to see if the resistance between the poles is normal. , the same type of device is consistent, and replace if necessary.

(8) Check the main contactor and other auxiliary contactors in the A1 and A2 incoming cabinets, and carefully observe whether the contactors of the contactors have arcing, burrs or surface oxidation, unevenness, and find such problems. The corresponding moving and static contacts are replaced to ensure that the contact is safe and reliable.

(9) Carefully check whether the terminal block is aging or loose, whether there is a hidden fault in the short circuit, whether the connection of each cable is firm, whether the wire is damaged or not, and whether the plugs of each circuit board are firmly connected. Whether the connection to and from the main power line is reliable, whether there is heat generation and oxidation at the connection, and whether the grounding is good.

(10) Whether the reactor has abnormal squeaking, vibration or odor.

Precautions for the surrounding environment of the inverter

The peripheral components of the inverter mainly include cables, contactors, air-openers, reactors, filters, and braking resistors. Whether the selection of the peripheral components of the inverter is correct or appropriate also directly affects the normal use of the inverter and the service life of the inverter. Therefore, after selecting the inverter, we must also correctly select its peripheral components. Below we will briefly explain the precautions for the selection of peripheral equipment.
Line breaker setting and selection
In order to protect the primary wiring on the power supply side of the inverter, install a wiring breaker. The choice of circuit breaker depends on the power factor on the power supply side (varies with supply voltage, output frequency, load). The operating characteristics are affected by the high-frequency current, and it is necessary to select a large capacity.
Line contactor
The inverter can be used without a line contactor. The line contactor can be stopped, but the brake function of the inverter will not be used.
Motor side contactor
If a contactor is provided between the inverter and the motor, it is in principle not allowed to switch during operation. When the inverter is connected during operation, there will be a large inrush current, so the inverter overcurrent protection action. When setting the contactor for switching to the grid, be sure to switch after the inverter stops output and use the speed search function as appropriate.
Thermal relay setting
In order to prevent the motor from overheating, the inverter has electronic thermal protection. However, when one inverter drives multiple motors and multi-stage motors, set a thermal relay between the inverter and the motor. The thermal relay is set to 1 times the motor nameplate at 50 Hz and 1.1 times at 60 Hz.
Power factor improvement
To improve the power factor, you can insert an AC reactor into the inverter’s incoming line or add a DC reactor to the DC loop. When the inverter output side is connected to the capacitor filter for improving the power factor, there is a danger of damage and overheating due to the high-frequency current output from the inverter. In addition, the inverter will overcurrent and cause current protection. Please do not connect the capacitor filter.
About radio interference
There is a high-frequency component in the output (main circuit) of the inverter, which can cause interference to communication devices (such as AM radios) used near the inverter. Filters can be installed to reduce interference. In addition, it is also effective to ground the inverter and the motor and the power supply wiring on the metal pipe.
Power cable wire diameter and wiring distance
When the wiring distance between the inverter and the motor is long (especially at low frequency output), the motor torque will drop due to the cable voltage drop; use a sufficiently thick cable wiring; when the operator is installed elsewhere, use a dedicated connection. Cable; when operating remotely, the distance between analog, control line and inverter should be controlled within 50 meters; the control signal should be properly shielded from ground.

Four common faults and incentives of the inverter

As a very popular control device in the field of electronic control, the frequency converter almost penetrates into every corner of industrial production activities. However, for some newcomers or newcomers who are just beginning to contact the inverter, they are still relatively unfamiliar and mysterious, especially if the inverter fails, it is easy to get started. Today, based on years of experience in using and overhauling inverters, I have summarized the four major faults common to inverters and given the relevant incentives for causing them.

First, over current (short circuit)
Overcurrent faults are most common among various faults in the frequency converter. This fault is mostly caused by the following problems: First, as long as the inverter speeds up, it reports a fault, indicating that the overcurrent is very serious, mostly the load short circuit, mechanical parts are stuck, the inverter module is soft breakdown damage and the acceleration time is over. Shortly caused; secondly, the inverter reports a fault when it is powered, and it cannot be “reset” to be eliminated. Most of it is caused by damage to the internal drive circuit of the inverter and damage to the current detection circuit. The last phenomenon is the most extreme. When the power is turned on instantaneously or after a short delay, it directly causes the upper air to trip and the internal fuselage is blown out or sparks. The inverter rectifier unit and the power inverter component directly cause breakdown failure. Second, overvoltage
This type of fault phenomenon is also often found in inverter faults. In addition to eliminating the supply voltage is too high, there is also a case of such a fault – when the inverter is stopped. The main reason for this may be caused by a slow deceleration time or a problem with the braking resistor and the brake unit.
Third, under voltage
The above overvoltage fault corresponds to the undervoltage fault of the inverter. Generally, the power supply voltage is too low. It may also be caused by the following reasons: the power supply phase loss, the open circuit fault of one bridge arm of the rectifier circuit, and the main circuit If the capacity of the filter electrolytic capacitor becomes small or a problem occurs in the voltage detection circuit, the inverter may experience an undervoltage fault. In addition, if the internal snubber resistance of the inverter is not cut off by short circuit, an undervoltage fault will occur as long as the inverter is loaded.
Fourth, over temperature
Over-temperature is also a common fault of the inverter. This fault is mostly caused by the temperature of the inverter working environment is too high, the cooling holes are blocked, the cooling fan is damaged, the temperature sensor and the temperature detection circuit are damaged.
Through the above analysis of the four common faults of the inverter (of course, faults such as overload and output imbalance), it is not difficult for the peers to see that the inverter needs to work harder in daily maintenance, and more needs to be done in daily maintenance. We will use it flexibly according to the situation on the spot, and try our best to prevent it before it happens!

How does the inverter control the motor speed and save energy?

1. Why is the rotational speed of the motor freely changeable?
Motor rotation speed unit: r/min The number of rotations per minute can also be expressed as rpm. For example: 2-pole motor 50Hz 3000 [r/min] 4-pole motor 50Hz 1500 [r/min]

Conclusion: The rotational speed of the motor is proportional to the frequency

The rotational speed of an inductive AC motor (hereinafter referred to simply as a motor) is approximately determined by the number of poles and frequency of the motor. The number of poles of the motor is fixed by the working principle of the motor. Since the pole value is not a continuous value (a multiple of 2, for example, the number of poles is 2, 4, 6), it is generally uncomfortable and the speed of the motor is adjusted by changing the value.

In addition, the frequency can be supplied to the motor after being adjusted outside the motor, so that the rotational speed of the motor can be freely controlled.

Therefore, the inverter for the purpose of controlling the frequency is the preferred device for the motor speed control device.

n = 60f/p

n: synchronization speed

f: power frequency

p: motor pole pairs

Conclusion: Changing frequency and voltage is the optimal motor control method

If only the frequency is changed without changing the voltage, the frequency will decrease and the motor will be over-voltage (overexcitation), causing the motor to be burned out. Therefore, the inverter must change the voltage at the same time while changing the frequency. When the output frequency is above the rated frequency, the voltage cannot continue to increase, and the maximum can only be equal to the rated voltage of the motor.

For example, in order to reduce the rotational speed of the motor by half, change the output frequency of the inverter from 50Hz to 25Hz, then the output voltage of the inverter needs to be changed from 400V to about 200V.
2. What is the output torque when the motor’s rotational speed (frequency) changes?
The starting torque and maximum torque when the inverter is driven are less than that of the direct-frequency power supply. When the motor is powered by the commercial power supply, the starting and acceleration shocks are large, and when the inverter is used for power supply, these impacts are weaker. A direct start of the power frequency produces a large starting and starting current. When the inverter is used, the output voltage and frequency of the inverter are gradually added to the motor, so the starting current and impact of the motor are smaller. Generally, the torque produced by the motor is reduced as the frequency decreases (the speed decreases). The reduced actual data is given in some of the drive manuals.

By using a flux vector controlled inverter, the torque of the motor at low speeds is improved, and even in the low speed range, the motor can output sufficient torque.
3. When the inverter is adjusted to a frequency greater than 50Hz, the output torque of the motor will decrease.
The usual motor is designed and manufactured at a voltage of 50 Hz, and its rated torque is also given within this voltage range. Therefore, the speed regulation below the rated frequency is called constant torque speed regulation. (T=Te, P<=Pe) When the inverter output frequency is greater than 50Hz, the torque generated by the motor should be linearly inversely proportional to the frequency. decline. When the motor is running at a frequency greater than 50 Hz, the size of the motor load must be considered to prevent the motor from outputting insufficient torque.

For example, the torque generated by the motor at 100 Hz is reduced to approximately 1/2 of the torque at 50 Hz.

Therefore, the speed regulation above the rated frequency is called constant power speed regulation. (P=Ue*Ie)
4. Application of inverter above 50Hz
As you know, the rated voltage and current rating of a particular motor are constant. If the inverter and motor are rated: 15kW/380V/30A, the motor can work above 50Hz. When the speed is 50Hz, the output voltage of the inverter is 380V, and the current is 30A. At this time, if the output frequency is increased to 60Hz, the maximum output voltage of the inverter can only be 380V/30A. Obviously, the output power is unchanged. So we call it constant power speed regulation.

What is the torque situation at this time?

Because P = wT (w: angular velocity, T: torque). Because P does not change, w increases, so the torque will decrease accordingly.

We can also look at another angle:

The stator voltage of the motor U = E + I*R (I is the current, R is the electronic resistance, and E is the induced potential)

It can be seen that when U, I are unchanged, E does not change.

And E = k*f*X, (k: constant, f: frequency, X: flux), so when f is from 50–>60Hz, X will decrease accordingly.

For the motor, T = K * I * X, (K: constant, I: current, X: flux), so the torque T will decrease as the flux X decreases.

Meanwhile, when it is less than 50 Hz, since I*R is small, when U/f=E/f is constant, the magnetic flux (X) is constant. The torque T is proportional to the current. This is why the inverter is usually used. Overcurrent capability to describe its overload (torque) capability. Also known as constant torque regulation (rated current is constant –> maximum torque is constant)

Conclusion: When the inverter output frequency increases from above 50Hz, the output torque of the motor will decrease.
5. Other factors related to output torque
The heat and heat dissipation capacity determine the output current capability of the inverter, which affects the output torque capability of the inverter. Carrier frequency: Generally, the rated current of the inverter is the highest carrier frequency, and the value of continuous output can be guaranteed at the highest ambient temperature. When the carrier frequency is reduced, the current of the motor will not be affected. However, the heat of the components will decrease. Ambient temperature: It is not like increasing the protection current value of the inverter because it detects that the ambient temperature is low.

Altitude: The altitude increases, which has an effect on heat dissipation and insulation performance. Generally, it can be ignored below 1000m. Above 5% per 1000m can be used.

11 benefits of using a frequency converter

There are many benefits to using a frequency converter:

1. First use a cage induction motor that is inexpensive and easy to maintain. Moreover, the original induction motor can be directly used without modifying the mechanical and drive system to improve the mechanical function.

2. Continuous, extensive operation is possible. When using the original common power supply, use another variable speed device (reducer, belt, etc.) for shifting. However, only phase shifting is possible and continuous shifting is not possible.

3. Inverter can replace DC engine, then use induction motor. Like the DC engine, it does not require a brush, slip-ring, etc., and is excellent in maintainability and environmental resistance.

4. The inverter can be soft-started and soft-closed to adjust the acceleration/deceleration time of the engine.

5. Reduce the starting current. Through the soft start and soft shutdown of the inverter, the starting current can be reduced to 1.5~2 times of the rated current when the motor starts. Generally, when the direct-in starts, the starting current of the current rated current is 6 times, so it will load the frequent running/stopping of the motor.

6. The inverter’s rebound brake facilitates electric braking.

7. One engine can be controlled in parallel with one inverter.

8. High efficiency.

9. Use inverters in ventilators, pumps, etc. to reduce energy; for air conditioning equipment, to create a comfortable environment.

10. It can perform high speed operation above the rated motor current.

11. Use the best speed control to improve quality.

Causes and treatment methods of inverter tripping fault

One. Power failure handling
If the power supply is temporarily powered off or the voltage is low, the “undervoltage” display, or the “overvoltage” display of this transient overvoltage may cause the inverter to trip and stop. Generally, the power can be restarted after the power supply returns to normal.
2. External fault handling
If the input signal is open, the output line is open circuit, phase failure, short circuit, grounding or insulation resistance is very low, the motor is faulty or overloaded, etc., the inverter will display “external” fault and trip and stop. After the fault is eliminated, it can be re-enabled.
three. Internal fault handling
If the internal fan is open or overheated, the fuse is open, the device is overheated, the memory is faulty, the CPU is faulty, etc., it can be switched to the power frequency operation without affecting the production. After the internal fault is eliminated, the inverter operation can be resumed.

In the event of an internal fault in the inverter unit, if it is within the warranty period, the manufacturer or the manufacturer’s agent should be notified as soon as possible to be responsible for the warranty. Perform the following checks based on the category and data displayed by the fault:

1. After opening the chassis, first check whether there are any broken wires, solder joints, burnt smells or deterioration of the components inside, if necessary, do the corresponding treatment in time.

2. Use a multimeter to check the resistance of the resistor and the on-off resistance of the diode, switch tube and module to determine whether to break or break down. If yes, replace it with the original nominal value and the withstand voltage value, or replace it with the same type.

3. Use the dual trace oscilloscope to detect the waveform of each working point, and use the step-by-step elimination method to judge the fault location and components.

Issues to be aware of during maintenance:

1. Strictly prevent false soldering, virtual connection, or wrong soldering, continuous soldering, or miswired, especially do not mistakenly connect the power cable to the output.

2. Power-on static check indicator, digital tube and display are normal, and the preset data is appropriate.

3. If there are conditions, a small motor can be used for the simulation dynamic test.

4. With load test.

four. Improper handling of function parameters
When the parameters are preset, the no-load test is normal. If an “overcurrent” trip occurs after loading, the starting torque setting may be insufficient or the acceleration time may be insufficient. Some may also decrease the moment of inertia after running for a period of time, resulting in “overvoltage” during deceleration. “Trip, generally modify the function parameters and then increase the acceleration time to solve.

Need help? Email Us Here! Chat With Us Now!

← Prev Step

Thanks for contacting us. We'll get back to you as soon as we can.

Please provide a valid name, email, and question.

Powered by LivelyChat
Powered by LivelyChat Delete History