【Daily Question 20090305】Time adjustment of the inverter?

If the acceleration or deceleration time of the inverter is not set appropriately, overcurrent or overvoltage can occur during acceleration or deceleration, causing the inverter to trip. At this point, it is necessary to adjust the acceleration and deceleration times in order to eliminate the overvoltage or overcurrent generated by the regenerated energy. If such a fault occurs during operation, increase the acceleration and deceleration times appropriately. This post was last edited by chinahbzq on 2009-3-4 20:51]

During the operation of manufacturing machinery, the acceleration process represents a transition from one state to another. During this period, no production activities take place. From the perspective of improving productivity, it is desirable for the acceleration time to be as short as possible. However, a shorter acceleration time along with a faster increase in frequency can lead to overcurrent. Therefore, the principle behind setting the acceleration time is to keep it as short as feasible, while ensuring that overcurrent does not occur. Some loads, such as water pumps and fans, have no requirements regarding start-up and stop-time, so the acceleration and deceleration times can be set to be longer. The deceleration process, just like the acceleration process, is also a transitional phase from one state to another; the shorter this period, the better. However, the shorter the time, the faster the frequency drops, which can lead to an excessive increase in the DC voltage and cause it to exceed the allowable limits. In practical applications, an appropriate deceleration time should be determined based on the conditions of the DC voltage. For pump loads, due to the resistance of the liquid, the pump stops almost immediately once the power is cut off, as there is no inertia. However, to prevent water hammer effects from damaging the pump, a longer deceleration time is chosen ； Fan-type loads have high inertia, so the speed reduction time should be set to be longer.

1. How to determine the deceleration time during debugging? First, set the deceleration time to be longer, and observe the DC voltage during the motor’s deceleration process. Within the allowable range of the DC voltage, minimize the deceleration time. 2. How to set the acceleration time during debugging? \"Ramp-up time\" is defined as the time required for the output frequency of the inverter to increase from 0Hz to the maximum frequency fmax. Generally speaking, the shortest starting time at which the starting current does not exceed the motor’s rated current is preferred. If the load requires rapid startup, the shortest startup time should be chosen such that the starting current does not exceed the rated current of the inverter. First, set the rise time to a longer value and observe the magnitude of the starting current. Gradually shorten the acceleration time until the above requirements are met. This post was last edited by *anpangpang on 2009-3-5 08:38]

During the operation of manufacturing machinery, the acceleration process represents a transition from one state to another. During this period, no production activities take place. From the perspective of improving productivity, it is desirable for the acceleration time to be as short as possible. However, a shorter acceleration time along with a faster increase in frequency can lead to overcurrent. Therefore, the principle behind setting the acceleration time is to keep it as short as feasible, while ensuring that overcurrent does not occur. Some loads, such as water pumps and fans, have no requirements regarding start-up and stop-time, so the acceleration and deceleration times can be set to be longer. The deceleration process, just like the acceleration process, is also a transitional phase from one state to another; the shorter this period, the better. However, the shorter the time, the faster the frequency drops, which can lead to an excessive increase in the DC voltage and cause it to exceed the allowable limits. In practical applications, an appropriate deceleration time should be determined based on the conditions of the DC voltage. For pump loads, due to the resistance of the liquid, the pump stops almost immediately once the power is cut off, as there is no inertia. However, to prevent water hammer effects from damaging the pump, a longer deceleration time is chosen ； Fan-type loads have high inertia, so the speed reduction time should be set to be longer.

\"Ramp-up time\" is defined as the time required for the output frequency of the inverter to increase from 0Hz to the maximum frequency fmax. Generally speaking, the shortest starting time at which the starting current does not exceed the motor’s rated current is preferred. If the load requires rapid startup, the shortest startup time should be chosen such that the starting current does not exceed the rated current of the inverter. The deceleration time set by the inverter refers to the time required for its output frequency to drop from the maximum value to 0. During deceleration, the frequency first decreases, and the speed of the rotating magnetic field falls below the speed of the rotor, causing the motor to operate in generator (regenerative) mode. The kinetic energy of the motor is converted into electrical energy, which is fed back to the DC section through the freewheeling diodes of the inverter bridge, where it is dissipated by the braking resistor RB. If the speed is reduced too quickly, the braking resistor RB does not have enough time to dissipate the electrical energy regenerated by the motor, resulting in an excessively high DC voltage across the filter capacitors and causing \"overvoltage\".

Thank you to the people who replied above; I now know a bit more about frequency converters

During the operation of manufacturing machinery, the acceleration process represents a transition from one state to another. During this period, no production activities take place. From the perspective of improving productivity, it is desirable for the acceleration time to be as short as possible. However, a shorter acceleration time along with a faster increase in frequency can lead to overcurrent. Therefore, the principle behind setting the acceleration time is to keep it as short as feasible, while ensuring that overcurrent does not occur. Some loads, such as water pumps and fans, have no requirements regarding start-up and stop-time, so the acceleration and deceleration times can be set to be longer. The deceleration process, just like the acceleration process, is also a transitional phase from one state to another; the shorter this period, the better. However, the shorter the time, the faster the frequency drops, which can lead to an excessive increase in the DC voltage and cause it to exceed the allowable limits. In practical applications, an appropriate deceleration time should be determined based on the conditions of the DC voltage. For pump loads, due to the resistance of the liquid, the pump stops almost immediately once the power is cut off, as there is no inertia. However, to prevent water hammer effects from damaging the pump, a longer deceleration time is chosen ； Fan-type loads have high inertia, so the speed reduction time should be set to be longer.

The acceleration time is defined as the time required for the output frequency of the inverter to rise from 0 Hz to the maximum frequency fmax. Generally speaking, the shortest starting time at which the starting current does not exceed the motor’s rated current is preferred. If the load requires rapid startup, the shortest startup time should be chosen such that the starting current does not exceed the rated current of the inverter. During debugging, it is generally advisable to set the rise time to a longer value first in order to observe the magnitude of the starting current. Gradually shorten the acceleration time until it meets the requirements. The deceleration time refers to the time it takes for its output frequency to drop from the maximum frequency to 0. When the speed decreases, the frequency drops first; the speed of the rotating magnetic field becomes lower than that of the rotor, putting the motor in a generator (regenerative) mode. The kinetic energy of the motor is converted into electrical energy, which is fed back to the DC section through the freewheeling diodes of the inverter bridge, where it is dissipated by the braking resistor RB. If the speed is reduced too quickly, the braking resistor RB does not have enough time to dissipate the electrical energy regenerated by the motor, resulting in an excessively high DC voltage across the filter capacitors and causing \"overvoltage\". When setting the speed reduction, first set the speed reduction time to be longer, and observe the DC voltage during the motor’s speed reduction process. Within the allowable range of the DC voltage, minimize the deceleration time.

Yes, I have encountered such problems before; when the No. 1 pump stopped, the inverter experienced an overcurrent fault. After increasing the deceleration time, no further issues occurred.

Generally, it still needs to be adjusted based on the load conditions; the time required for heavy loads and light loads is definitely different :)

Acceleration time control: 1. It can be illustrated with an analogy – for instance, when you are running, if you need to accelerate from a standing still state to your maximum speed in a very short amount of time, it’s possible for your body to suddenly exert excessive force and strain the muscles that haven’t yet warmed up properly； If you gradually reach your top speed based on your own abilities, it will feel very easy. Deceleration time control: 2. When you are running at high speed and want to stop, if you need to come to a stop within 2 meters, you must rely on external obstacles to do so; however, using such obstacles improperly can cause harm to your body. On the other hand, if you want to stop within 20 meters, it will be easy, and no external force is needed – you can simply use inertia to gradually bring yourself to a stop. In fact, the control of the acceleration and deceleration times of inverters works on the same principle!

When accelerating an inverter, the type of load must be taken into consideration; for example, when driving a conveyor belt that is 2–4 kilometers long, the acceleration process takes a long time, and the acceleration time we use is as much as 5 minutes.