The function and working principle of synchronous transformer

Synchronous transformer is a special purpose transformer that plays an important role in power systems and power electronic devices. It is mainly used to provide synchronization signals for power electronic devices such as thyristors, ensuring that these devices can be controlled according to predetermined phase angles. The following is a detailed explanation of the function and working principle of synchronous transformers.

The function of synchronous transformer

1. Synchronization signal provision: The main function of a synchronous transformer is to provide synchronization signals for power electronic devices such as thyristors. These signals are usually synchronized with the voltage waveform of the power grid, ensuring that the thyristor receives the trigger pulse at the correct time.

2. Voltage conversion: Synchronous transformers can convert high-voltage AC signals into low-voltage signals to meet the needs of control circuits.

3. Isolation protection: Synchronous transformers can provide synchronous signals while also achieving electrical isolation, protecting control circuits from the influence of high-voltage circuits.

4. Phase control: In some applications, synchronous transformers can also be used to control the triggering phase of thyristors, thereby achieving precise control of the power system.

Working principle

The working principle of synchronous transformers is based on the principle of electromagnetic induction, which means that when the primary coil (high voltage side) passes through alternating current, a changing magnetic flux will be generated in the iron core of the transformer, and this changing magnetic flux will induce current in the secondary coil (low voltage side).

1. Electromagnetic induction: The primary and secondary coils of the transformer are wound around the same iron core. When the primary coil is connected to an AC power source, the magnetic flux in the iron core will change with the variation of AC power, thereby generating induced electromotive force in the secondary coil.

2. Phase relationship: Since the primary coil and the secondary coil share the same iron core, the induced electromotive force in the secondary coil maintains the same frequency and phase relationship as the voltage in the primary coil.

3. Voltage conversion: The number of turns of the primary and secondary coils of the transformer is different, which leads to voltage conversion. According to the basic principle of transformers, the ratio of the secondary voltage to the primary voltage is equal to the ratio of the number of turns of the secondary coil to the number of turns of the primary coil.

4. Isolation function: As the primary and secondary coils are electrically independent, the transformer provides good electrical isolation, preventing direct impact of high voltage on the control circuit.

Application scenarios

Synchronous transformers are widely used in the following fields:

1. Power system: In high-voltage direct current transmission and flexible alternating current transmission systems, synchronous transformers are used to control the triggering of thyristors to achieve precise control of power flow.

2. Power electronics: In various power electronics converters, synchronous transformers are used to provide synchronous signals for devices such as thyristors, ensuring the correct triggering of the devices.

3. Motor control: In the motor drive system, synchronous transformers can be used to provide trigger signals synchronized with the power grid to control the speed and direction of the motor.

4. Measurement and protection: In the measurement and protection equipment of the power system, synchronous transformers are used to provide reference signals synchronized with the grid voltage.