Application of Current Sensor in Rectified Power Supply

Application of Current Sensor in Rectified Power Supply

As the core equipment for converting AC power to DC power, rectifier power supply is widely used in industrial automation, new energy generation, electric vehicle charging and other fields. With the development of power electronics technology, the efficiency and reliability requirements of rectifier power supplies are increasingly high, and current sensors, as key components for real-time monitoring and control, play an important role in rectifier power supply systems. However, complex environmental factors such as temperature, humidity, electromagnetic interference, etc. can directly affect the performance and system stability of current sensors. This article will start from the application scenarios of current sensors in rectifier power supplies, analyze their mechanism of action and the influence of environmental factors.

1、 The core application of current sensors in rectifier power supplies

1. Input/output current monitoring

In rectifier circuits, current sensors are usually deployed on the AC input side and DC output side:

Input side: Monitor the amplitude, phase, and harmonic components of the grid current to provide data support for power factor correction (PFC) and overcurrent protection.

Output side: Real time feedback of DC bus current, used for dynamic load regulation and short-circuit protection, such as preventing battery overcharging in electric vehicle charging stations.

2. Overload and short circuit protection

Rectified power supplies may generate transient high currents when subjected to sudden loads or short circuits. Hall effect current sensors (such as closed-loop Hall sensors) can quickly trigger the turn off action of IGBT or MOSFET with high response speed (μ s level) and wide dynamic range (0~1000A), protecting power devices from damage.

3. Efficiency optimization and harmonic suppression

By using high-precision current sensors (such as flux gate sensors) to collect current waveform data and combining it with DSP or FPGA for FFT analysis, harmonic components can be identified and control algorithms can be optimized. For example, in the rectification process of a photovoltaic inverter, current sensor data can assist in achieving maximum power point tracking.

2、 The Influence of Environmental Factors on the Performance of Current Sensors

1. Temperature fluctuations

Drift effect: The temperature coefficient of semiconductor materials (such as the sensitivity of Hall elements with a temperature drift of about 0.05%/℃) can cause zero shift and gain error. For example, in high temperature environments (>85 ℃), changes in the resistance of shunt resistors may cause a measurement deviation of ± 1%.

Solution: Adopt temperature compensation circuit (such as PT1000 thermistor feedback) or choose wide temperature range sensor (such as SiC based magnetoresistance sensor at -40~125 ℃).

2. Electromagnetic interference (EMI)

Coupling noise: Electromagnetic noise generated by high-frequency switching devices in rectifier power supplies may interfere with sensor signals through spatial radiation or conduction paths. Experiments have shown that unshielded Hall sensors can achieve an error of over 5% under 10MHz noise.

Suppression measures: Adopt differential signal transmission, ferrite magnetic ring filtering, or integrated EMI shielding cover (such as aluminum shell+conductive gasket).

3. Mechanical vibration and humidity

Structural reliability: Vibration environment (such as wind power converters) may cause internal solder joint breakage or magnetic core displacement of the sensor. For example, in random vibration (5-2000Hz, 10Grms) testing, the failure rate of non reinforced sensors increased by 30%.

Moisture proof design: In environments with humidity>90% RH, the leakage current of the sensor PCB may increase, and it is necessary to use potting glue (such as polyurethane) or IP67 or higher protection level packaging.