BL6533

BL6533

BL6533

BL6533

Single Phase Energy Meter IC with LCD

Single Phase Energy Meter IC with LCD

Single Phase Energy Meter IC with LCD

Single Phase Energy Meter IC with LCD D

DD

Driver

river

river

river

http://www.belling.com.cn

- 7 -

9/9/2009

Total 10 Pages

The average active power is related to the cosine value of the phase difference between the voltage

signal and the current signal. This cosine value is called as Power Factor (PF) of the two channel signals.

Figure1.

The Effect of phase

When the signal phase difference between the voltage and current channels is more than 90

°, the

average active power is negative. It indicates the user is using the electrical energy reversely.

Operation Process

In BL6533, the two ADCs digitize the voltage signals from the current and voltage transducers. These

ADCs are 16-bit second order sigma-delta with an oversampling rate of 900 kHz. This analog input

structure greatly simplifies transducer interfacing by providing a wide dynamic range for direct

connection to the transducer and also simplifying the antialiasing filter design. A programmable gain

stage in the current channel further facilitates easy transducer interfacing. A high pass filter in the

current channel removes any dc component from the current signal. This eliminates any inaccuracies in

the real power calculation due to offsets in the voltage or current signals.

The real power calculation is derived from the instantaneous power signal. The instantaneous power

signal is generated by a direct multiplication of the current and voltage signals. In order to extract the

real power component (i.e., the dc component), the instantaneous power signal is low-pass filtered.

Figure 2 illustrates the instantaneous real power signal and shows how the real power information can be

extracted by low-pass filtering the instantaneous power signal. This scheme correctly calculates real

power for nonsinusoidal current and voltage waveforms at all power factors. All signal processing is

carried out in the digital domain for superior stability over temperature and time.