Inverter related issues
How to choose v/f curve:
(1) Below the fundamental frequency, the output voltage changes linearly with respect to the output frequency:
Applicable to transportation machinery, driving, roller drive and other devices that have constant load torque even if the speed changes.
(2) Below the fundamental frequency, the output voltage changes by the second power curve with respect to the output frequency:
Suitable for equipment such as blower, water pump, etc. where the load torque is proportional to the square of the speed.
(3) v/f curve between 1 and 2.
Applies to loads that are between squared-curve and constant-torque characteristics.
In addition, when it is suitable for lifting a load, positive and negative torque boost values ​​can be set according to actual conditions.
Most frequency converters have a variety of v/f selections or adjustments.
Energy-saving operation under v/f control:
Mainly for fans, pumps.
When the load is large or the acceleration and deceleration are frequent, the energy saving effect is not good.
Different inverter manufacturers open parameters are different, generally choose whether to enter the energy-saving mode. Take the Mitsubishi FR-A700 as an example, there is a parameter "energy saving control option", set to 4 to enter the energy saving control mode, the best excitation control can be achieved, and there is an energy saving monitor, and the related energy saving index can be observed.
Many inverters have the setting of no-load excitation current. Setting this parameter low will help to save energy in no-load conditions, but it will also affect the carrying capacity.
First, and how to set each parameter to make it more energy-efficient
The frequency changer function parameter is many, generally has tens or even hundreds of parameters for the user to choose. In practical applications, it is not necessary to set and debug each parameter. Most of the parameters are factory set values.
A deceleration time
The acceleration time is the time required for the output frequency to increase from zero to the maximum frequency, and the deceleration time is the time required to fall from the maximum frequency to zero. Normally, the acceleration/deceleration time is determined by the rise and fall of the frequency setting signal. When the motor accelerates, the rate of rise of the frequency setting must be limited to prevent over-current, and when decelerating, the rate of decrease should be limited to prevent over-voltage.
Acceleration time setting requirements: Limit the accelerating current below the overcurrent capacity of the inverter, and cause the inverter to trip without over-current stalling. The deceleration time setting points are: to prevent the smoothing circuit voltage from being too large, and not to make the regeneration overvoltage stall. Make the frequency converter trip. Acceleration/deceleration time can be calculated according to the load, but in the debugging often take the load and experience to set a longer acceleration and deceleration time, through the start, stop the motor to observe whether there is over current, over voltage alarm; then gradually set the acceleration and deceleration time Shortened to ensure that the best acceleration/deceleration time can be determined by repeating the operation several times with the principle of no alarm in operation.
Second torque increase
Also called torque compensation is a method of increasing the low frequency range f/V in order to compensate for torque reduction at low speed caused by the stator winding resistance of the motor. When set to automatic, the voltage at the time of acceleration can be automatically increased to compensate for the starting torque and smooth the motor acceleration. If manual compensation is used, a better curve can be selected by the test according to the load characteristics, especially the starting characteristics of the load. For the variable torque load, if the improper selection is made, the output voltage at the low speed will be too high and the power will be wasted. Even if the motor starts with the load, the current will be large and the speed will not increase.
Three electronic thermal overload protection
This function is set to protect the motor from overheating. It is the CPU in the inverter that calculates the temperature rise of the motor based on the running current value and frequency, so as to perform overheat protection. This function is only applicable to "one-on-one" occasions. When "one to many" is required, thermal relays should be installed on each motor.
Electronic thermal protection set value (%) = [motor rated current (A) / inverter rated output current (A)] × 100%.
Four frequency restrictions
That is, the inverter output frequency upper and lower limit amplitude. The frequency limit is a protection function that prevents the output frequency from becoming too high or too low to prevent misoperation or external frequency setting signal source failure. In the application can be set according to the actual situation. This function can also be used as a speed limit, such as some belt conveyors, due to the transport of material is not too much, in order to reduce the wear of the machinery and the belt, can drive by the inverter, and set the inverter upper frequency to a certain frequency value This allows the belt conveyor to operate at a fixed, lower operating speed.
Five offset frequency
Some are also called deviation frequency or frequency deviation setting. Its purpose is to use this function to adjust the output frequency of the frequency setting signal when the frequency is set by an external analog signal (voltage or current). When some frequency converters set the frequency setting signal to 0%, the deviation value can be used within the range of 0 to fmax. Some inverters (such as Mingdian and Sanhe) can also set the offset polarity. If the frequency setting signal is 0% in the debugging, the output frequency of the inverter is not 0Hz, but is xHz, then setting the offset frequency to negative xHz can make the inverter output frequency to 0Hz.
Six frequency setting signal gain
This function is only valid when the frequency is set with an external analog signal. It is used to compensate for the inconsistency between the externally set signal voltage and the voltage inside the inverter (+10v); at the same time, it is convenient for the analog setting signal voltage to be selected. When the analog input signal is set to the maximum (such as 10v, 5v or 20mA), find the percentage of frequency that can output f/V graph and set it as a parameter; if the external setup signal is 0~5v, if the inverter output frequency is 0~50Hz, then the gain signal will be Set it to 200%.
Seven torque limit
Can be divided into two kinds of drive torque limit and brake torque limit. It is based on the inverter output voltage and current value, the torque calculation by the CPU, which can significantly improve the impact load recovery characteristics of acceleration and deceleration and constant speed operation. The torque limit function enables automatic acceleration and deceleration control. Assuming that the acceleration/deceleration time is less than the load inertia time, the motor can also be guaranteed to automatically accelerate and decelerate according to the torque setpoint.
The drive torque function provides powerful starting torque. In the steady state operation, the torque function will control the motor slip, and limit the motor torque to the maximum set value. When the load torque suddenly increases, even When the acceleration time is set too short, it will not cause the inverter to trip. When the acceleration time is set too short, the motor torque will not exceed the maximum set value. Larger drive torque is favorable for starting, and it is better to set 80 to 100%.
The smaller the setting value of the braking torque, the greater the braking force is, and it is suitable for the occasion of rapid acceleration and deceleration. For example, if the setting value of braking torque is set too large, an over-voltage alarm phenomenon will occur. If the braking torque is set to 0%, the total amount of regenerative energy added to the main capacitor can be made close to zero, so that the motor can decelerate to a stop without tripping without using a braking resistor during deceleration. However, on some loads, if the braking torque is set to 0%, there will be a brief idling during deceleration, which will cause the inverter to start repeatedly and the current will fluctuate greatly. In severe cases, the inverter will trip, and attention should be paid.
Eight acceleration and deceleration mode selection
Also called acceleration and deceleration curve selection. Generally frequency converter has linear, non-linear and S three kinds of curves, usually choose linear curve mostly; Non-linear curve is suitable for changing torque load, such as fan,etc.; S curve is suitable for constant torque load, its acceleration and deceleration change is more slowly. According to the characteristics of the load torque, set the corresponding curve, but there are exceptions, the author when debugging a boiler induced draft fan inverter, the first to choose the non-linear curve acceleration and deceleration curve, together with the inverter to run the trip, adjust Changing many parameters has no effect, and it becomes normal after changing to S curve. The reason for this is as follows: Before the start of the induced draft fan due to the flue gas flow and self-rotation, and reversed to become a negative load, so select the S curve, so that the frequency of just starting the rise is slow, thus avoiding the inverter The occurrence of tripping is, of course, the method used for inverters that do not have a DC braking function.
Nine torque vector control
The vector control is based on the theory that the asynchronous motor and the DC motor have the same torque generation mechanism. The vector control method is to decompose the stator current into the specified magnetic field current and torque current, respectively, to control, and at the same time, output the combined stator current to the motor. Therefore, the same control performance as the DC motor can be obtained in principle. With the torque vector control function, the motor can output maximum torque under various operating conditions, especially when the motor is in a low speed operation area.
Nowadays, almost all frequency converters use non-feedback vector control. Because the frequency converter can compensate for slip according to the magnitude and phase of the load current, the motor has very hard mechanical characteristics. It can meet the requirements for most occasions, and it is not necessary to use the inverter. Externally set speed feedback circuit. The setting of this function can be based on the actual situation in the effective and invalid one can be selected.
The related function is the slip compensation control. The function is to compensate the speed deviation caused by the load fluctuation, and the slip frequency corresponding to the load current can be added. This function is mainly used for positioning control.
Ten Energy Saving Control
Fans and pumps are all reduced torque loads. That is, as the speed decreases, the load torque is proportional to the square of the speed, while the inverter with energy-saving control function is designed with a dedicated V/f mode. This mode can be improved. The efficiency of the motor and frequency converter, which can automatically reduce the output voltage of the inverter according to the load current, so as to achieve the purpose of energy saving, can be set as valid or invalid according to the specific circumstances.
The above is what I have previously downloaded and stored, because it is about the inverter parameter settings, may be used, they are all affixed, and not too much ha ~ ~
As for the issue of energy saving, I did not understand it. Should the inverter allow the entire system (water supply, exhaust, etc.) to save energy, without involving its own energy saving? Select the inverter for the air pump, there are energy-saving V/f mode inside, and the setting can be effective.
How to choose v/f curve:
(1) Below the fundamental frequency, the output voltage changes linearly with respect to the output frequency:
Applicable to transportation machinery, driving, roller drive and other devices that have constant load torque even if the speed changes.
(2) Below the fundamental frequency, the output voltage changes by the second power curve with respect to the output frequency:
Suitable for equipment such as blower, water pump, etc. where the load torque is proportional to the square of the speed.
(3) v/f curve between 1 and 2.
Applies to loads that are between squared-curve and constant-torque characteristics.
In addition, when it is suitable for lifting a load, positive and negative torque boost values ​​can be set according to actual conditions.
Most frequency converters have a variety of v/f selections or adjustments.
Energy-saving operation under v/f control:
Mainly for fans, pumps.
When the load is large or the acceleration and deceleration are frequent, the energy saving effect is not good.
Different inverter manufacturers open parameters are different, generally choose whether to enter the energy-saving mode. Take the Mitsubishi FR-A700 as an example, there is a parameter "energy saving control option", set to 4 to enter the energy saving control mode, the best excitation control can be achieved, and there is an energy saving monitor, and the related energy saving index can be observed.
Many inverters have the setting of no-load excitation current. Setting this parameter low will help to save energy in no-load conditions, but it will also affect the carrying capacity.
First, and how to set each parameter to make it more energy-efficient
The frequency changer function parameter is many, generally has tens or even hundreds of parameters for the user to choose. In practical applications, it is not necessary to set and debug each parameter. Most of the parameters are factory set values.
A deceleration time
The acceleration time is the time required for the output frequency to increase from zero to the maximum frequency, and the deceleration time is the time required to fall from the maximum frequency to zero. Normally, the acceleration/deceleration time is determined by the rise and fall of the frequency setting signal. When the motor accelerates, the rate of rise of the frequency setting must be limited to prevent over-current, and when decelerating, the rate of decrease should be limited to prevent over-voltage.
Acceleration time setting requirements: Limit the accelerating current below the overcurrent capacity of the inverter, and cause the inverter to trip without over-current stalling. The deceleration time setting points are: to prevent the smoothing circuit voltage from being too large, and not to make the regeneration overvoltage stall. Make the frequency converter trip. Acceleration/deceleration time can be calculated according to the load, but in the debugging often take the load and experience to set a longer acceleration and deceleration time, through the start, stop the motor to observe whether there is over current, over voltage alarm; then gradually set the acceleration and deceleration time Shortened to ensure that the best acceleration/deceleration time can be determined by repeating the operation several times with the principle of no alarm in operation.
Second torque increase
Also called torque compensation is a method of increasing the low frequency range f/V in order to compensate for torque reduction at low speed caused by the stator winding resistance of the motor. When set to automatic, the voltage at the time of acceleration can be automatically increased to compensate for the starting torque and smooth the motor acceleration. If manual compensation is used, a better curve can be selected by the test according to the load characteristics, especially the starting characteristics of the load. For the variable torque load, if the improper selection is made, the output voltage at the low speed will be too high and the power will be wasted. Even if the motor starts with the load, the current will be large and the speed will not increase.
Three electronic thermal overload protection
This function is set to protect the motor from overheating. It is the CPU in the inverter that calculates the temperature rise of the motor based on the running current value and frequency, so as to perform overheat protection. This function is only applicable to "one-on-one" occasions. When "one to many" is required, thermal relays should be installed on each motor.
Electronic thermal protection set value (%) = [motor rated current (A) / inverter rated output current (A)] × 100%.
Four frequency restrictions
That is, the inverter output frequency upper and lower limit amplitude. The frequency limit is a protection function that prevents the output frequency from becoming too high or too low to prevent misoperation or external frequency setting signal source failure. In the application can be set according to the actual situation. This function can also be used as a speed limit, such as some belt conveyors, due to the transport of material is not too much, in order to reduce the wear of the machinery and the belt, can drive by the inverter, and set the inverter upper frequency to a certain frequency value This allows the belt conveyor to operate at a fixed, lower operating speed.
Five offset frequency
Some are also called deviation frequency or frequency deviation setting. Its purpose is to use this function to adjust the output frequency of the frequency setting signal when the frequency is set by an external analog signal (voltage or current). When some frequency converters set the frequency setting signal to 0%, the deviation value can be used within the range of 0 to fmax. Some inverters (such as Mingdian and Sanhe) can also set the offset polarity. If the frequency setting signal is 0% in the debugging, the output frequency of the inverter is not 0Hz, but is xHz, then setting the offset frequency to negative xHz can make the inverter output frequency to 0Hz.
Six frequency setting signal gain
This function is only valid when the frequency is set with an external analog signal. It is used to compensate for the inconsistency between the externally set signal voltage and the voltage inside the inverter (+10v); at the same time, it is convenient for the analog setting signal voltage to be selected. When the analog input signal is set to the maximum (such as 10v, 5v or 20mA), find the percentage of frequency that can output f/V graph and set it as a parameter; if the external setup signal is 0~5v, if the inverter output frequency is 0~50Hz, then the gain signal will be Set it to 200%.
Seven torque limit
Can be divided into two kinds of drive torque limit and brake torque limit. It is based on the inverter output voltage and current value, the torque calculation by the CPU, which can significantly improve the impact load recovery characteristics of acceleration and deceleration and constant speed operation. The torque limit function enables automatic acceleration and deceleration control. Assuming that the acceleration/deceleration time is less than the load inertia time, the motor can also be guaranteed to automatically accelerate and decelerate according to the torque setpoint.
The drive torque function provides powerful starting torque. In the steady state operation, the torque function will control the motor slip, and limit the motor torque to the maximum set value. When the load torque suddenly increases, even When the acceleration time is set too short, it will not cause the inverter to trip. When the acceleration time is set too short, the motor torque will not exceed the maximum set value. Larger drive torque is favorable for starting, and it is better to set 80 to 100%.
The smaller the setting value of the braking torque, the greater the braking force is, and it is suitable for the occasion of rapid acceleration and deceleration. For example, if the setting value of braking torque is set too large, an over-voltage alarm phenomenon will occur. If the braking torque is set to 0%, the total amount of regenerative energy added to the main capacitor can be made close to zero, so that the motor can decelerate to a stop without tripping without using a braking resistor during deceleration. However, on some loads, if the braking torque is set to 0%, there will be a brief idling during deceleration, which will cause the inverter to start repeatedly and the current will fluctuate greatly. In severe cases, the inverter will trip, and attention should be paid.
Eight acceleration and deceleration mode selection
Also called acceleration and deceleration curve selection. Generally frequency converter has linear, non-linear and S three kinds of curves, usually choose linear curve mostly; Non-linear curve is suitable for changing torque load, such as fan,etc.; S curve is suitable for constant torque load, its acceleration and deceleration change is more slowly. According to the characteristics of the load torque, set the corresponding curve, but there are exceptions, the author when debugging a boiler induced draft fan inverter, the first to choose the non-linear curve acceleration and deceleration curve, together with the inverter to run the trip, adjust Changing many parameters has no effect, and it becomes normal after changing to S curve. The reason for this is as follows: Before the start of the induced draft fan due to the flue gas flow and self-rotation, and reversed to become a negative load, so select the S curve, so that the frequency of just starting the rise is slow, thus avoiding the inverter The occurrence of tripping is, of course, the method used for inverters that do not have a DC braking function.
Nine torque vector control
The vector control is based on the theory that the asynchronous motor and the DC motor have the same torque generation mechanism. The vector control method is to decompose the stator current into the specified magnetic field current and torque current, respectively, to control, and at the same time, output the combined stator current to the motor. Therefore, the same control performance as the DC motor can be obtained in principle. With the torque vector control function, the motor can output maximum torque under various operating conditions, especially when the motor is in a low speed operation area.
Nowadays, almost all frequency converters use non-feedback vector control. Because the frequency converter can compensate for slip according to the magnitude and phase of the load current, the motor has very hard mechanical characteristics. It can meet the requirements for most occasions, and it is not necessary to use the inverter. Externally set speed feedback circuit. The setting of this function can be based on the actual situation in the effective and invalid one can be selected.
The related function is the slip compensation control. The function is to compensate the speed deviation caused by the load fluctuation, and the slip frequency corresponding to the load current can be added. This function is mainly used for positioning control.
Ten Energy Saving Control
Fans and pumps are all reduced torque loads. That is, as the speed decreases, the load torque is proportional to the square of the speed, while the inverter with energy-saving control function is designed with a dedicated V/f mode. This mode can be improved. The efficiency of the motor and frequency converter, which can automatically reduce the output voltage of the inverter according to the load current, so as to achieve the purpose of energy saving, can be set as valid or invalid according to the specific circumstances.
The above is what I have previously downloaded and stored, because it is about the inverter parameter settings, may be used, they are all affixed, and not too much ha ~ ~
As for the issue of energy saving, I did not understand it. Should the inverter allow the entire system (water supply, exhaust, etc.) to save energy, without involving its own energy saving? Select the inverter for the air pump, there are energy-saving V/f mode inside, and the setting can be effective.