Will the freewheeling diode circuit formed when the relay is disconnected not damage the power supply?

A relay is an electronic device that primarily controls larger currents or voltages by inputting small currents or voltages into a circuit. This device mainly consists of an electromagnetic coil, a switch, and a spring. When current passes through a coil, it generates a magnetic field that attracts the switch and causes it to close. In this way, larger currents or voltages can flow through the switch. When the current stops flowing, the spring will push the switch back to its original position and disconnect the circuit.

Firstly, let's understand the working principle of the freewheeling diode. When the relay is disconnected, the current of the inductive element will generate magnetic field energy. When the switch is turned on, the current of the inductive component will instantly decrease, and the magnetic field energy needs to be released. During this process, a reverse voltage, also known as self induced voltage, is generated between the two terminals of the inductive element.

  When an inductive component (such as a relay) in a circuit is suddenly disconnected, it generates a reverse voltage surge. If there is no freewheeling diode, this reverse voltage may damage other parts of the circuit. A freewheeling diode protects a circuit by allowing current to flow freely in one direction, thereby eliminating this reverse voltage.

The function of a freewheeling diode is actually to transfer the energy generated in the relay to other circuits to prevent damage. When the current of the inductive component decreases and a reverse voltage is generated, the freewheeling diode releases this energy into other circuits through its own conduction. Due to the reverse polarity of the freewheeling diode, it will only conduct under reverse voltage conditions and will not conduct during normal operation.

Now let's discuss the topic: Will the freewheeling diode circuit formed when the relay is disconnected damage the power supply?

The answer is no. The circuit formed by the freewheeling diode is a closed local circuit, whose main function is to provide a release path for the induced current in the relay coil. The current in this circuit is driven by the induced electromotive force generated inside the relay coil, rather than being provided by the power source. Therefore, the current in the freewheeling circuit will not flow back into the power supply, and will not cause any damage to the power supply.

In fact, using a freewheeling diode not only does not damage the power supply, but is also a measure to protect the power supply. Because without a freewheeling diode, the back electromotive force may generate some unpredictable high-voltage pulses through the power supply line, which is a potential risk for both the power supply and the entire circuit system. The freewheeling diode avoids this risk by providing a safe release path.

In summary, the freewheeling diode circuit formed when the relay is disconnected is a very important and effective protective measure. It releases the induced current in the coil by providing a closed local circuit, thereby avoiding arcing and voltage pulses caused by high back electromotive force, and protecting the components in the circuit, including the power supply. Therefore, using a freewheeling diode does not damage the power supply, but rather serves as a form of protection for the power supply.