Development of AC Regulated Power Supply by Instantaneous Comparison Method
Regulated power supplies are devices used to stabilize grid voltage and have been widely applied in China for many years. Typical types include sliding contact voltage regulators driven by servo motors, variable reactor type and magnetic saturation type automatic AC voltage stabilizers.
All the above power supplies work by sampling grid voltage signals, conducting comparison processing, and adopting servo motors or contactless switches to realize regulation so as to output stable AC voltage. Such devices generally have unsatisfactory voltage stabilization performance with accuracy ranging from 1% to 0.5%.
Current AC regulated power supplies mainly have the following defects: (1) The adoption of nonlinear reactors easily generates harmonics, failing to optimize grid voltage waveform quality, and even causing additional waveform distortion and grid harmonic pollution. (2) Excessively long sampling time and actuator response time.
These two factors greatly restrict the overall performance of voltage stabilizers. Most devices adopt effective value or average value sampling which takes several power frequency cycles to complete. In addition, servo motors usually spend several seconds to tens of seconds to finish regulation action, resulting in slow response and no improvement on voltage waveform. Such regulation modes cannot respond timely to fast-changing grid disturbances such as surge voltage, voltage sag, pulse interference and high-frequency interference. These disturbances will pass through the stabilizer and affect electrical loads, failing to provide effective protection and possibly leading to abnormal operation or even equipment damage.
Therefore, it is of great significance to develop voltage stabilizers that can rapidly restore output voltage to the rated value when grid voltage fluctuates or suffers interference, and supply sinusoidal AC power with standard waveform and stable amplitude for the normal operation of electrical equipment.
