基于AS8002設計的太陽能電源逆變技術
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Power inverters in solar photovoltaic systems are often connected directly to the electricity grid in order to inject the created energy into the mains and act as an electricity supplier. This energy must comply with certain regulations that set the standard in terms of quality and safety which requires of accurate measurements.
The AS8002 is a highly accurate measurement IC that allows monitoring the generated energy with low cost shunt resistors or other sensors for the current and resistor dividers for the voltage.
This approach allows avoiding more expensive sensing devices while achieving the required accuracy for DC and AC measurements of current and voltage, as well as stability over the operating temperature range of the inverter.
The 12-bit ADC samples the voltage and current and provides their instantaneous values through an SPI interface.
The 12-bit ADC is preceded by low noise programmable gain amplifiers in order to accommodate different sensors.
The ADC has three multiplexed inputs, offering one secondary channel in addition to the main voltage and current.
The on-chip temperature sensor provides the inverter designer the option of temperature compensation for any of the measured parameters or functional blocks provided, over the full operating temperature range of the device.
The on-chip voltage reference is connected to the ADC and to REF. An external crystal oscillator is not required as a high accuracy internal oscillator clock is available.
The independent over current interrupt detects a high current on the grid and allows the processor to open the switches without waiting for the ADC conversion.
AS8002主要特性:
12-Bit 100 kSPS ADCs for accurate voltage and current measurement
Programmable gain amplifiers to accommodate for different sensors
Three multiplexed inputs to the 12-Bit ADC for secondary measurements that require high accuracy and fast sampling rates
On chip temperature sensor connected to one of the inputs of the multiplexer
On-chip voltage reference with small temperature coefficient (10ppm/K typ). This reference is available at the pin REF.
Low power on chip oscillator
SPI compatible interface
Internal registers for easy offset and gain compensation
Interrupt alerts (including Under Voltage Lock-Out and Over Temperature)
Independent programmable over current interrupt
AS8002應用:
The AS8002 is suitable for PV inverter grid monitoring, Wind inverter grid monitoring, Isolated voltage sensing, Uninterruptible Power supplies and Power conditioners.
圖1.AS8002方框圖
圖2.AS8002典型應用電路圖
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