Three-phase voltage regulator is a commonly used power electronic device used to stabilize AC voltage and protect load equipment from voltage fluctuations to achieve stable power supply. Unbalanced output of three-phase load means that the three-phase load current or power is not equal, resulting in different three-phase output voltage and imbalance. This article will introduce in detail the working principle of three-phase voltage regulator and how to achieve balanced output of three-phase load.
Working principle of three-phase voltage regulator
Three-phase voltage regulator can achieve stable output voltage through volt-band resistor, transformer and power transistor. Its working principle is as follows:
Transformer: Three-phase voltage regulator uses transformer to convert input voltage into corresponding low voltage or high voltage to achieve voltage stability. The conversion ratio of transformer can be designed according to specific application requirements.
Volt-band resistor: The function of volt-band resistor is to limit the input current of voltage regulator and ensure the safety of input circuit of voltage regulator. When the input voltage is too high, the resistance value of volt-band resistor will decrease, which is conducive to the voltage regulator control circuit to control the input voltage within a stable range.
Power transistor: Power transistor is the core component of the voltage regulator, which is used to control the current between the output voltage and the load, so as to achieve the stability of the output voltage. Through PWM regulation technology, that is, adjusting the switching time of each transistor, the output current balance and voltage stability can be achieved.
Reasons for unbalanced output of three-phase load of three-phase voltage regulator
In the actual application of three-phase voltage regulator, due to unbalanced load current or power, the three-phase output voltage will be different, resulting in unbalanced output of three-phase load. The main reasons for unbalanced output of three-phase load are as follows:
1. Unbalanced load current: Different loads in the three-phase load circuit may cause different three-phase currents, resulting in different three-phase output voltages.
2. Transient load: If the transient load such as starting motor, transformer is too large, it will cause different three-phase output voltages.
3. Load system imbalance: If the three-phase capacitor is damaged or the circuit contact is poor, it will cause the three-phase circuit to be unbalanced, resulting in different three-phase output voltages.
How to achieve balanced output of three-phase load of three-phase voltage regulator
To achieve balanced output of three-phase load of three-phase voltage regulator, the following steps need to be taken:
1. Select the appropriate voltage regulator model: According to the specific application scenario, select the appropriate voltage regulator model to ensure that it can withstand the situation of unbalanced load current.
2. Reasonable design of voltage regulator circuit: In order to avoid the influence of transient load on the output voltage of voltage regulator, it is necessary to reasonably design the voltage regulator circuit, such as adding step-down circuit, adding output filter, etc.
3. Real-time monitoring of load current: Add current monitoring circuit to the input circuit of voltage regulator, monitor the change of load current in real time, adjust the output voltage of voltage regulator and PWM control mode of power transistor according to load current, and ensure the balance of three-phase output voltage.
4. Regular maintenance and inspection circuit: During use, the circuit needs to be checked and maintained regularly to avoid imbalance of voltage regulator due to circuit aging, component damage, etc.
Summary
Three-phase voltage regulator is a commonly used power electronic device, which is used to stabilize AC voltage and protect load equipment from voltage fluctuations to achieve the purpose of stable power supply. Unbalanced three-phase load output means that the three-phase load current or power is not equal, resulting in different three-phase output voltages and imbalance. To achieve balanced three-phase load output of a three-phase voltage stabilizer, it is necessary to select a suitable voltage stabilizer model, reasonably design the voltage stabilizer circuit, monitor the load current in real time, and regularly maintain and inspect the circuit.
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