Elmo SERVO AMPLIFIER DBP SERIES - Manual (Page 99)

98
DBP - Rev 6/93
Appendix A - Current loop response
In most applications it is not necessary to adjust the current loop to
achieve the optimum response. When there are extreme electrical parameters in
the armature circuit (inductance and resistance) the standard components values
of 0.01
µ
F for C1 and 100Kohm for R4 may not yield with the optimum response.
The current loop should be optimized as follows:
- Insert R7 (1K) to connect the tacho input to the error amplifier. The
amplifier must not be configured into velocity mode. If the resolver option
is used, make sure that DS11 is OFF.
- Apply power to the amplifier and send the command BA.
- Provide the tacho input H/R-12b,E-J3/23 with a bi-directional square wave
current command (100-200Hz, +2.0V waveform is often employed).
- Monitor the load current either by a current probe or by the current monitor.
If the current response is not critically damped, use the following
procedure:
- Short circuit C1 with a short jumper wire.
- Replace R4 with a decade resistance box. Initially set the box resistance at
10Kohm.
- Apply the square wave test signal to the amplifier input.
- Apply power, and while monitoring the load current, gradually increase the
value of the box resistance until optimum response as depicted in Fig A-1 is
achieved.
- Substitute the closest standard value discrete resistor for R4 and remove the
decade resistance box.
- Remove the shorting jumper across C1, and again check the response using the
square wave test signal.
- If the previous step does not yield satisfactory results, if unacceptable
overshooting has been noted, substitute a larger value than 0.01
µ
F; or, if
the response is overdamped, substitute a smaller value than 0.01
µ
F.
Repetition of this procedure should yield an optimum choice for C1.