SA9904B is an electric energy metering chip designed and developed by South Africa Microelectronics Systems Co., Ltd.,
ATY7026A is an electric energy metering chip developed by Zhuhai Juli IC Design Co., Ltd.,
CS5463 is a single-phase bidirectional power/electric energy metering integrated circuit chip with serial interface, which is introduced by CRYSTAL Company of the United States. These three methods are all used for three-phase multi-functional electric energy metering, which are all suitable for three-phase three-wire power grid with standard frequency of 50 Hz or 60 Hz, and support two ways: resistance network meter calibration and software meter calibration. Because electric energy measurement, parameter measurement and data reading are the core parts of power chip. The following mainly introduces the chip principle from six aspects: active power measurement, reactive power measurement, apparent power/electric energy measurement, effective value measurement, interrupt and SPI interface.
2. Introduction to1sa9904b
SA9904B has 20 pins, PDIP package and 12 meta registers. SA9904B contains nine 24-bit registers, which respectively represent the active energy, reactive energy and power supply voltage of each phase. The 65438th+00th 24-bit register represents the local frequency of any valid phase, including three addresses to maintain compatibility with SA9604A. Any of the three addresses can be used to access the frequency register. The active and reactive power of each phase is stored in a 24-bit register. The electric energy or power of the tested circuit is not directly provided to the user, but can be calculated by formula. Calculate the active or reactive energy of each phase: each energy count = (= (Vrated× irarated)/320 000; 000; Calculate the active or reactive power of each phase: power = Vrated× irarated× n/inttime/320 000. Where: VRATED is the rated power supply voltage of the electric meter, IRATED is the rated power supply current of the electric meter, N= the difference of register values between consecutive readings (delta value), and INTTIME is the time difference between consecutive readings (in seconds). If the combined phase active energy is needed, the three-phase active energy can only be summed by the program or counted by the active power pulse output F50. The three voltage registers in the chip contain the root mean square voltage values of each phase, which can be directly read by users. SA9904B has no interrupt function. Serial Peripheral Interface Bus (SPI) is a synchronous bus used for data transmission between microcontroller and SA9904B. Pins D0 (serial data output), DI (serial data input), CS (chip option) and SCK (serial clock) are used for the application of this bus. SA9904B is the slave device and the microcontroller is the bus master device. CS input starts and ends data transmission. The SCK signal (sent by the microcontroller) gates the data between the microcontroller and the SCK pin of SA9904B. DI and DO pins are serial data input and output pins of SA9904B.
2.2 introduction of att 7026a
Att 7026a has 44 pins, QFP44 package and 102 register flip. Active power is obtained by calculating the algebraic average of instantaneous power. The active power of split-phase and combined-phase is stored in the specified register for users to read. The reactive power can be obtained by shifting the voltage sampling signal by 90 degrees and then calculating the algebraic average of instantaneous power. It also provides users with split-phase and combined-phase reactive power. The chip has a built-in energy accumulation register, which can provide split-phase, combined-phase active and reactive energy, but does not provide grid cycle accumulation mode. The chip provides clock calibration pulse CFl and low frequency pulse F 1/F2 to drive the stepping motor through the energy pulse generator. Because the chip provides the effective values of current and voltage, users can also use the formula S=VRMS×IRMS to measure the apparent power of split phase and combined phase through MCU. Effective value measurement is achieved by finding the mean square of voltage and current sampling data. The effective values of six channels can be calculated at the same time, and the results are stored in the specified register for users to read. In addition, the chip not only provides the effective values of phase current and voltage, but also provides the effective values of the sum of three-phase current and voltage vectors, which can be read by users in designated registers. ATT7026A has no interrupt function. SPI serial communication interface is integrated in the chip, using two control lines and two data lines. The command word for updating the calibration table data register is: the highest two bits are 10, and the lower six bits are the address of the calibration table register; The command word for writing special command word operation (with the help of software lookup table) is: the highest 2 bits are 1 1, and the lower 6 bits are the type of special command word. The chip provides four special commands: data clear, data read, data write enable and software reset.
2.3 introduction to cs5463
CS5463 has 24 pins, SSOP package and 32 registers. The digital quantities of transient voltage and current are obtained by sampling, and the sampling value of instantaneous active power is obtained by multiplying the data of each pair of transient voltage and current. After each A/D sampling period, new instantaneous power samples are stored in the power register, and n instantaneous power samples are grouped. The accumulated values of each group are used to calculate the value to be put into the energy register later, which is proportional to the active power value of the circuit in n analog-to-digital conversion cycles. In the same principle, the effective values of voltage and current are also calculated by using the latest n transient voltage and current samples, and can be read from the rms voltage and current registers. The apparent power can be directly read in the apparent power register or measured by pulses proportional to the apparent power output by E2. CS5463 has interrupt function. Interrupt processing flow is as follows: read the status register → prohibit all interrupts → go to the corresponding interrupt handler → write back the read value reset status register → reopen the interrupt → return from the interrupt handler. The serial port of CS5463 includes four control lines: CS, SDI, SDO and SCLK. If the chip selection CS is directly connected to logic 0, only three wires are needed to complete the serial port operation. Data transmission always starts with sending an 8-bit command to SDI of serial interface. When the command contains a write operation, the serial port will continue to read serial data from the SDI pin for the next 24 SCLK cycles. When a read command is issued, the serial port will output the register contents serially from the SD0 pin in the next 8, 16 and 24 SCLK cycles according to the issued command.