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5. Background-information to the H-Bridge
circuits
A H-bridge is an electronic circuit which allows us to reverse the
polarity of a device (such as a DC-motor) by controlling four switches.
These H-bridges will often be found in robotics to control a motor
rotation in two opposite directions.
Modern systems use integrated circuits for motor control, but to learn
the basic fundamentals and the dimensioning problems of power
supplies it might be important to study an archaic circuit for motor
controls.
5.1 A H-Bridge for 3 Volt Power supplies
The driver circuit for the Hyper-Peppy robots contains two PNP-Tran-
sistors TR7 and TR8, respectively NPN-Transistors TR9 and TR10. In
this design we always allow only two transistors to simultaneously
conduct currents into motor M:
via TR7 and TR10 or alternatively
via TR8 and TR9.
The (freely available test-version of the) Microcap simulator allows us
to comfortably calculate the DC-simulation for the circuit and read the
values from the schematic window:
I
Afb. 8: simulation for the
H-bridge in the Hyper Peppy
robot