Does The Servo Lose Power When It Vibrates? How To Deal With Power Supply Current Limitation And Teach You How To Solve It Completely

The most troublesome thing about playing with theservois that as soon as the power is turned on, theservoshakes like a sieve, or it doesn't move at all. Nine times out of ten, this is the power supply current limiting protection being triggered. To put it bluntly, the power supply could not supply the large current that theservosuddenly needed. In order to protect itself, it "snapped" the power. Don’t worry, let’s talk about how to solve this problem thoroughly today.

Why does the servo trigger power current limit?

This is actually a physics problem. The steering gear is essentially a high-power motor. Especially when starting, carrying a load, or suddenly reversing from high speed, it needs to draw huge current in an instant. For example, for an ordinary metal servo, the current may surge to several amperes when the rotor is blocked. If your power supply can only output a maximum of 5A, and the servo needs 8A instantly, the overcurrent protection of the power supply will be activated immediately, and the output voltage will drop or even be cut off. This is like using water during the morning rush hour in a community. Every household turns on the faucet. If the main water pipe pressure is not enough, your shower will naturally drip.

How to calculate the total current required by the servo

We have to figure out how to settle the accounts, otherwise all the power supplies we buy will be in vain. You need to know two values: the operating current of the servo and the locked-rotor current. The working current is the consumption when it is idling, and the locked-rotor current is the maximum consumption when it is stuck and working hard. If you use multiple servos, do not simply add up the stall currents of all servos, because it is difficult for all servos to stall at the same time. A relatively safe algorithm is: add up the working current of all servos, plus the blocking current of one or two servos that are expected to be blocked at the same time, leaving a margin of 20% to 30%, which is basically stable.

Which current power supply is most suitable?

Now that you know how much power you need, it’s time to choose a power source. My suggestion is, if your budget and space allow, try to choose one with a higher current. For example, if you calculate that the system peak value requires 10A, then it will be more secure to buy a 12V 15A or even 20A switching power supply. A high-current power supply with a small load works very easily, the voltage ripple is small, and the servo movement will be smoother and more accurate. It's like asking a strong man to move a table. He can do it easily without sweating profusely and making his hands shake.

Can capacitors solve the problem of instantaneous current shortage?

This is a very good remedy. Connecting a large capacitor in parallel between the power supply and the servo is like building a "small reservoir" for the system. When the servo needs a large current in an instant and the power supply has no time to respond, the electric energy stored in the capacitor will be released immediately to help you survive those most critical hundreds of milliseconds. This method is especially suitable for battery-powered applications. Although the battery has sufficient overall power, its instantaneous discharge capacity may not be enough. Capacitors can make up for this shortcoming.

How to troubleshoot if the power supply has current limit?

Don’t panic if you hit the upper limit, let’s take it step by step. ️First, disconnect all servos and use a multimeter to check whether the no-load voltage of the power supply is normal. ️Then, connect only one servo and let it move slowly to see if the protection will still be triggered. If not, add them one by one to see which number causes the problem. In this way, it can be determined whether the power supply is insufficient or whether a certain servo itself is short-circuited or damaged. Many times, the problem lies in a faulty steering gear, which itself is a "big power consumer".

How to limit servo current in software

In addition to hardware, we can also do some tricks in the program. The current of the steering gear is directly related to its speed and torque. You can use code to slow down the speed at which the servo turns from one angle to another, which means it takes longer to move. In this way, the current will not rush to the peak value instantly, but will be "flattened". In addition, try to avoid having all servos start up at the same time or perform extreme actions at the same time. Using a delay to stagger them by a few tenths of a second can effectively stagger the current spikes and allow the power supply to breathe.

After talking so much, I wonder where is your current steering gear project? The power problem you are currently encountering, is it protected as soon as it is turned on, or does it only lose power when a heavy load is in operation? Welcome to chat about your situation in the comment area, and let's find a solution together. If you find the article useful, don’t forget to like it and share it with more friends who play servos!