I. AC voltage stabilizer
While there are many types of AC voltage regulators, and their main circuit working principles differ, they are basically all composed of an input switching sampling circuit, a control circuit, a voltage regulation device, an output protection device, and a drive device (with the exception of AC parameter voltage regulators).
1. Input switch: As the input working switch of the voltage regulator, it is generally a miniature circuit breaker with current limiting protection, which can protect the voltage regulator and electrical equipment.
2. Voltage regulator: This is a device that can adjust the output voltage. It can raise or lower the output voltage and is the most important component of the voltage regulator.
3. Sampling circuit: It detects the output voltage and current of the voltage regulator and transmits the changes in output voltage to the control circuit.
4. Drive device: Since the control signal of the control circuit is relatively weak, a drive device is needed to amplify and convert the power.
5. Drive protection device: A device that connects and disconnects the output of a voltage regulator, usually a relay, contactor, or fuse.
6. Control Circuit: It analyzes the sampled circuit detection model. When the output voltage is too high, it sends a control signal to the drive device to reduce the voltage, and the drive device will drive the voltage regulator to lower the output voltage. When the output voltage is too low, it sends a control signal to the drive device to increase the voltage, and the drive device will drive the voltage regulator to increase the output voltage, thereby stabilizing the output voltage and achieving the purpose of stable output.
When the output voltage or current exceeds the regulator's control range, the control circuit will activate the output protection device to disconnect the output and protect the electrical equipment. Under normal conditions, the output protection device is connected, ensuring a stable voltage supply to the electrical equipment.
II. Classification of AC voltage stabilizers
1. Ferroresonant AC voltage regulator
An AC voltage regulator is made by combining a saturated choke and a corresponding capacitor to achieve constant voltage-current characteristics. The magnetic saturation type is an early typical structure of this type of regulator. It is simple in structure, easy to manufacture, has a wide allowable input voltage range, is reliable in operation, and has strong overload capacity. However, it has significant waveform distortion and low stability. More recently developed voltage-stabilizing transformers are also power supply devices that achieve voltage stabilization through the nonlinearity of electromagnetic components. The difference between them and magnetic saturation regulators lies in the different magnetic circuit structures, while their basic working principles are the same. They achieve both voltage stabilization and transformation on a single iron core, making them superior to ordinary power transformers and magnetic saturation regulators.
2. Magnetic amplifier type AC voltage regulator
A voltage regulator is a device that connects a magnetic amplifier and an autotransformer in series, using electronic circuitry to change the impedance of the magnetic amplifier to stabilize the output voltage. Its circuit configuration can be linear amplification or pulse width modulation, etc. This type of voltage regulator has a closed-loop system with feedback control, resulting in high stability and a good output waveform. However, because it uses a magnetic amplifier with significant inertia, the recovery time is relatively long. Furthermore, due to the use of an autotransformer, its anti-interference capability is relatively poor.
3. Sliding AC voltage stabilizer
A device that stabilizes the output voltage by changing the position of the transformer's sliding contacts is called a servo motor-driven automatic voltage regulating AC regulator. These regulators are highly efficient, produce good output voltage waveforms, and have no special requirements regarding the load characteristics. However, their stability is relatively low, and their recovery time is relatively long.
4. Inductive AC voltage stabilizer
This device stabilizes the output AC voltage by changing the phase difference between the secondary voltage and the primary voltage of a transformer. Structurally, it resembles a wound-rotor induction motor, while in principle it is similar to an induction voltage regulator. It has a wide voltage regulation range, good output voltage waveform, and can achieve power outputs of several hundred kilowatts. However, because the rotor is often in a stalled state, it has high power consumption and low efficiency. Furthermore, due to the high consumption of copper and iron, its production is relatively limited.
5. Thyristor AC voltage regulator
An AC voltage regulator that uses thyristors as power adjustment elements. It has advantages such as high stability, fast response, and no noise. However, it can damage the mains waveform and cause interference to communication and electronic equipment.
6. Relay-type AC voltage stabilizer
An AC voltage regulator that uses a relay to adjust the windings of an autotransformer. It has advantages such as a wide voltage regulation range, fast response speed, and low production cost. It is used for street lighting and in relatively remote residential applications.
III. New Type of AC Voltage Regulator
1. Compensated AC voltage stabilizer
Also known as a partially regulated voltage regulator. It utilizes an additional voltage from a compensation transformer connected in series between the power supply and the load. As the input voltage varies, an intermittent AC switch (contactor or thyristor) or a continuous servo motor is used to change the magnitude or polarity of the additional voltage, subtracting (or adding) the excess (or insufficient) portion of the input voltage, thus achieving voltage stabilization. The compensation transformer's capacity is only about 1/7 of the output power, offering advantages such as simple structure and low cost, but its stability is not high.
2. CNC AC voltage stabilizers and stepper voltage stabilizers
The control circuit, composed of logic elements or microprocessors, converts the number of primary turns of the transformer according to the input voltage level to stabilize the output voltage.
3. Purified AC voltage stabilizer
It is used because of its good isolation properties, which can eliminate peak interference from the power grid.
