Dc servo bipolar control

Posted on Nov 29, 2012

This circuit accepts bipolar control inputs of ± 5 V and provides a phase-chopped output to a dc load (such as a servo motor) of the same polarity as the input. The rms voltage of the output is closely proportional to the control input voltage. N-channel and p-channel TMOS devices', Ql and Q2, are connected in anti-series to form a bidirectional switch through which current can flow in either the forward or reverse direction. Control circuits turn Ql and Q2 on when they are reverse biased, bypassing their reverse rectifier and increasing circuit efficiency. Each device is allowed to turn off only when forward biased.

Dc servo bipolar control
Click here to download the full size of the above Circuit.

The Q1-Q2 switch connects the ac power source to the load when its instantaneous voltage is the same polarity and less than the control voltage. Ula is configured as an ideal positive rectifier whose output follows the control voltage when it is positive, and is zero otherwise. Similarly, Ulb is a negative rectifier. Ulc turns Ql on whenever the ac input voltage is lower than the positive rectifier output. For negative control voltages, Ql is turned on only during the negative half-cycle. For positive control voltages, Ql is turned on during the end portions of the positive half-cycle. Similarly, Uld turns Q2 on whenever the ac input voltage is higher than the output of the negative rectifier.

Leave Comment

characters left:

New Circuits



Popular Circuits

Power down function
Super Class-A 30W Amplifier
ADSL Splitter Adapter
Transistor Voltage buffer Follower
Toy Motor Drivers
simple tiny door guard
UPB1009K Necs Low Power Gps Rf Receiver Bipolar Analog Integrated Circuit
CB transmitter
Frequency counter using PIC16f84
Based on the LT3755 50W white LED headlight drive circuit diagram
High-power motor control circuit summary
Monostable circuit diagram of a light control