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U211B Datasheet(PDF) 5 Page - TEMIC Semiconductors |
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U211B Datasheet(HTML) 5 Page - TEMIC Semiconductors |
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5 / 20 page  U211B2/ B3 TELEFUNKEN Semiconductors Rev. A1, 29-May-96 5 (20) C = 1 mF 10 V 95 10363 18 17 16 15 123 4 R = 1 M W Figure 5. Operation delay Control Amplifier (Figure 2) The integrated control amplifier with differential input compares the set value (Pin 11) with the instantaneous value on Pin 10 and generates a regulating voltage on the output Pin 12 (together with the external circuitry on Pin 12) which always tries to hold the actual voltage at the value of the set voltages. The amplifier has a transmittance of typically 1000 mA/V and a bipolar current source output on Pin 12 which operates with typically ±110 mA. The amplification and frequency response are determined by R7, C7, C8 and R11 (can be left out). For open loop operation, C4, C5, R6, R7, C7, C8 and R11 can be omitted. Pin 10 should be connected with Pin 12 and Pin 8 with Pin 2. The phase angle of the triggering pulse can be adjusted using the voltage on Pin 11. An internal limitation circuit prevents the voltage on Pin 12 from becoming more negative than V16 + 1 V. Load Limitation The load limitation, with standard circuitry, provides absolute protection against overloading of the motor. the function of the load limiting takes account of the fact that motors operating at higher speeds can safely withstand large power dissipations than at lower speeds due to the increased action of the cooling fan. Similary, consider- ations have been made for short term overloads for the motor which are, in practice, often required. These finctions are not damaging and can be tolerated. In each positive half-cycle, the circuit measures via R10 the load current on Pin 14 as a potential drop across R8 and produces a current proportional to the voltage on Pin 14. This current is available on Pin 15 and is integrated by C9. If, following high current amplitudes or a large phase angle for current flow, the voltage on C9 exceeds an internally set threshold of approx. 7.3 V (reference voltage Pin 16) then a latch is set and the load limiting is turned on. A current source (sink) controlled by the control voltage on Pin 15 now draws current from Pin 12 and lowers the control voltage on Pin 12 so that the phase angle a is increased to amax. The simultaneous reduction of the phase angle during which current flows causes firstly: a reduction of the rotational speed of the motor which can even drop to zero if the angular momentum of the motor is excessively large, and secondly: a reduction of the potential on C9 which in turn reduces the influence of the current sink on Pin 12. The control voltage can then increase again and bring down the phase angle. This cycle of action sets up a “balanced condition” between the “current integral” on Pin 15 and the control voltage on Pin 12. Apart from the amplitude of the load current and the time during which current flows, the potential on Pin 12 and hence the rotational speed also affects the function of the load limiting. A current proportional to the potential on Pin 10 gives rise to a voltage drop across R10, via Pin 14, so that the current measured on Pin 14 is smaller than the actual current through R8. This means that higher rotational speeds and higher current amplitudes lead to the same current integral. Therefore, at higher speeds, the power dissipation must be greater than that at lower speeds before the internal threshold voltage on Pin 15 is exceeded. The effect of speed on the maximum power is determined by the resistor R10 and can therefore be adjusted to suit each individual application. If, after the load limiting has been turned on, the momentum of the load sinks below the “o-momentum” set using R10, then V15 will be reduced. V12 can then in- crease again so that the phase angle is reduced. A smaller phase angel corresponds to a larger momentum of the mo- tor and hence the motor runs up - as long as this is allowed by the load momentum. For an already rotating machine, the effect of rotation on the measured “current integral” ensures that the power dissipation is able to increase with the rotational speed. the result is: a current controlled accelleration run-up., which ends in a small peak of accel- leraton when the set point is reached. The latch of the load limiting is simultaneously reset. The speed of the motor is then again under control and it is capable of carrying its full load. The above mentioned peak of accelleration depends upon the ripple of actual speed voltage. A large amount of ripple also leads to a large peak of accelleration. The measuring resistor R8 should have a value which ensures that the amplitude of the voltage across it does not exceed 600 mV. |
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Similar Description - U211B |
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