STPM32 datasheet(26/89 Pages) STMICROELECTRONICS

26 / 89 page

The decimation ratio, out of the filter cascade, is 512 so that outputs of this block are parallel 24-bit data at a rated

frequency of 7.8125 kHz.

The decimation block has a magnitude response -3 dB band of 3.6 kHz and a 2.0 kHz flat band.

8.3.3

Filter block

The block includes:

•

DC cancellation filter (BHPFVx, BHPFCx bits)

•

Rogowski coil Integrator (ROCx bit)

•

Fundamental harmonic component filter.

Figure 31. Filter block diagram

Reactive

Filter

HPF

ROCOIL

INT

LPF

BHPFVx

BHPFCx

ROCx

Vx Data [23:0]

Cx Data [23:0]

Vx Fund[23:0]

Cx Fund[23:0]

BLPFVx

BLPFCx

CHVx[11:0]

CHCx [11:0]

Vx [23:0]

Cx [23:0]

8.3.4

DC cancellation filter

This block removes the DC component of signal from voltage and current signals.

It is a selectable block which can be bypassed in case of particular needs with BHPFVx and BHPFCx bits in

DSP_CR1 and DSP_CR2.

The filter has a passband at -3 dB of 8 Hz

BHPFVx = 0: voltage HPF is included for x channel

BHPFVx = 1: voltage HPF is bypassed for x channel

BHPFCx = 0: current HPF is included for x channel

BHPFCx = 1: current HPF is bypassed for x channel

Rogowski coil Integrator

ROCx bit in DSP_CR1 and DSP_CR2 selects the type of current sensors (CT, shunt or Rogowski coil):

ROCx = 0: channel x current sensor is CT or shunt

ROCx = 1: channel x current sensor is Rogowski coil

In case of ROCx = 1, integrator filter is included to integrate current signal coming from Rogowski coil current

sensor. Rogowski coil integrator is selectable independently for each current channel.

8.3.5

Fundamental component filter

This low-pass filter on the voltage and current signals is used to calculate: zero-crossing, period, phase angles

and fundamental active and reactive energy. Filtered voltage and current components are available on

DSP_REG6, DSP_REG7, DSP_REG8, DSP_REG9 named VxFund and CxFund.

8.3.6

Reactive filter

Reactive filter introduces a delay in current and voltage streams respectively; these signals are used to calculate

reactive power and energy.

STPM32, STPM33, STPM34

Functional description of the digital part

DS10272 - Rev 13

page 26/89

STPM32 Datasheet(PDF) 26 Page - STMicroelectronics

STPM32 Datasheet(HTML) 26 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89

Datasheet Download

Link URL