Delta frequency converter speed parameter settings must pay attention to these matters
Delta Inverter has many functional parameters, generally dozens or even hundreds Parameters are available for the user to select. In practice, it is not necessary to set and debug each parameter. Most of them only need to use the factory default settings. However, some parameters are related to the practical use, and some are related to each other, so it is necessary to set and debug according to practice. These common parameters include but are not limited to: launch data, pick command source, frequency given source, zui large frequency, zui small frequency, acceleration/deceleration time, V/F curve.
Because the function of each type of inverter is different, and the title of the same function parameter is also inconsistent, for the convenience of description, this article takes the basic parameter name of Fuji inverter as an example. Since the basic parameters are all available for all types of frequency converters, it is completely possible to bypass the class.
One acceleration/deceleration time
The acceleration time is the time required for the output frequency to rise from 0 to the large frequency of zui. The deceleration time refers to the time required to descend from the large frequency of zui to 0. The acceleration/deceleration time is usually determined by the frequency setting signal rising and falling. When the motor is accelerating, the rate of increase of the frequency setting must be constrained to avoid overcurrent, and when decelerating, the rate of descent is constrained to avoid overvoltage.
Speed up the time setting requirement: the current will be constrained below the overcurrent capacity of the inverter, and the inverter will not trip due to over-speed loss; the key to setting the deceleration time is to avoid excessive voltage of the smoothing circuit. The inverter is not tripped due to the regenerative overvoltage stall. The acceleration/deceleration time can be calculated according to the load calculation. However, in the commissioning, the long acceleration/deceleration time is set according to the load and experience. After the start and stop motor, the overcurrent and overvoltage alarms are observed. Then the acceleration and deceleration time is gradually adjusted. Shorten, in the absence of an alarm during work, repeat the operation a few times, you can determine the zui Jia plus deceleration time.
Also known as torque compensation, it compensates for the torque drop at low speed caused by the stator winding resistance of the motor, and increases the low frequency range f/V. Big way. When set to active, the voltage at the time of acceleration can be actively raised to compensate for the starting torque, so that the motor can be speeded up smoothly. If manual compensation is used, a better curve can be selected after testing according to the load characteristics, especially the starting characteristics of the load. Regarding the variable torque load, if the selection is not appropriate, the output voltage at the low speed will be too high, and the phenomenon of smashing the electric energy will even show that the current is large when the motor is loaded with the load, and the rotation speed is not going up.
Three-Electronic Thermal Overload Maintenance
This function is set to maintain the motor overheating. It is the CPU of the inverter that calculates the temperature rise of the motor based on the operating current value and frequency, and then overheats. maintain. This function is only applicable to the "one-for-one" occasion, and in the case of "one-to-one", a thermal relay should be added to each motor.
Electronic thermal maintenance set value (%) = [motor rated current (A) / inverter rated output current (A)] × 100%.
Four frequency constraints
is the upper and lower limits of the inverter output frequency. The frequency constraint is to prevent the malfunction or the external frequency setting signal source from malfunctioning, causing the output frequency to be too high or too low to prevent damage to the maintenance function of the device. In the application, it can be set according to the actual situation. This function can also be used for speed limit. If there are some belt conveyors, because there are not too many materials to be transported, in order to reduce the wear of machinery and belts, the inverter can be driven and the upper limit frequency of the inverter can be set to a certain frequency value. This allows the belt conveyor to operate at a fixed, low working speed.
Five Offset Frequency
Some are also known as error frequency or frequency error settings. Its purpose is to adjust the frequency setting signal zui when the frequency is set by the external analog signal (voltage or current), as shown in Figure 1. In some inverters, when the frequency setting signal is 0%, the error value can be applied in the range of 0 to fmax. Some inverters (such as Mingdianshe, Sanhao) can also set the bias polarity. For example, when the frequency setting signal is 0% during debugging, the inverter output frequency is not 0Hz, but is xHz. At this time, the offset frequency is set to negative xHz to make the inverter output frequency 0Hz.
Six Frequency Setting Signal Gain
This function is only useful when setting the frequency with an external analog signal. It is used to compensate for the inconsistency between the external set signal voltage and the voltage inside the inverter (+10v); together with the selection of the analog set signal voltage, the punctual time, when the analog input signal is large (such as 10v, 5v) Or 20mA), find the frequency percentage of the f/V pattern that can be output and set it as a parameter; if the external setting signal is 0~5v, if the output frequency of the inverter is 0~50Hz, the gain will be The signal can be set to 200%.
Seven Torque Constraints
can be divided into driving torque constraints and braking torque constraints. It is based on the output voltage and current value of the inverter, and is torque-calculated by the CPU, which can significantly improve the shock load recovery characteristics during acceleration and deceleration and constant speed operation. The torque constraint function enables active acceleration and deceleration control. It is also assumed that the motor accelerates and decelerates according to the torque set value when the acceleration/deceleration time is less than the load inertia time.
The drive torque function provides a strong starting torque. In steady state operation, the torque function will control the motor slip, and the motor torque will be constrained within the large set value of Zui. When the torque suddenly increases, even if the set time is too short, the inverter will not trip. When the acceleration time setting is too short, the motor torque will not exceed the large setting value of zui. A large driving torque is advantageous for starting, and is set to be 80 to 100%.
The smaller the brake torque setting value is, the larger the braking force is. For the case of suitable rapid acceleration and deceleration, if the brake torque setting value is set too high, an overvoltage alarm phenomenon will occur. If the braking torque is set to 0%, the total amount of regeneration applied to the main capacitor can be close to 0, and then the motor can be decelerated to stop without tripping without deceleration when the motor is decelerating. However, in some loads, if the braking torque is set to 0%, the time will be short and idling during deceleration, causing the inverter to start repeatedly, the current fluctuates greatly, and the inverter will trip when it is serious, which should cause attention. .
Eight-speed deceleration form selection
Also known as acceleration/deceleration curve selection. Generally, the inverter has three kinds of curves: linear, nonlinear and S. Usually, most of the linear curves are selected; the nonlinear curve is suitable for variable torque loads, such as fans; the S curve is suitable for constant torque loads, and the acceleration and deceleration changes are slow. According to the load torque characteristics, the corresponding curve can be selected according to the load torque characteristics. However, when debugging the inverter of a boiler induced draft fan, the first choice is to select the nonlinear curve of the acceleration/deceleration curve, and the inverter will trip and adjust together. Changing many parameters has no effect, and then it is normal after changing to S curve. The reason is: before starting, the induced draft fan rolls by itself due to the flue gas flow, and turns into a negative load, so the S curve is selected, so that the frequency rises slowly at the beginning, and then the inverter is prevented from tripping. The occurrence of this, of course, is the method chosen for the inverter that does not have the DC braking function.
Nine Torque Vector Maneuvering
Vector maneuvering is based on the theory that asynchronous motors have the same torque generation mechanism as DC motors. The vector control method is to decompose the stator current into the specified field current and torque current, and separately control the stator current to output the stator current to the motor. Thus, the same handling performance as the DC motor can be obtained in principle. The torque vector control function is selected, and the motor can output large torque in various operating conditions, especially in the low speed running region of the motor.
The current inverters all use non-reactive vector control. Because the inverter can compensate for the slip according to the magnitude and phase of the load current, the motor has very hard mechanical properties, which can meet the requirements in most occasions. There is no need to set the speed response circuit outside the inverter. This function can be selected according to the actual situation, one of useful and invalid.
The function associated with this is the slip compensation control, which is used to compensate for the speed error caused by load fluctuations, plus the slip frequency corresponding to the load current. This function is mainly used for positioning and manipulation.
Ten energy-saving control
Fans and pumps are all torque-reducing loads, that is, as the speed decreases, the load torque decreases in proportion to the square of the speed, and energy-saving operation is achieved. The function of the inverter is planned to have a special V/f form. This form can improve the power of the motor and the inverter. It can actively reduce the output voltage of the inverter according to the load current, and then achieve the purpose of energy saving. It can be set to useful or invalid depending on the specific situation. .
It should be noted that the two parameters of Nine and Ten are very advanced, but some users are unable to enable these two parameters in the equipment transformation, that is, the inverter trips frequently after stopping. Everything works fine after use. The reasons are as follows: (1) The difference between the original motor parameters and the motor parameters required by the inverter is too large.
(2) It is not good to know the function of setting parameters. For example, the energy-saving control function can only be used in the V/f control method, and cannot be used in the vector control method.
(3) The vector manipulation method is enabled, but the manual setting and active reading of the motor parameters are not performed, or the reading method is not appropriate.