Motor driver
kyocera ringtones cheap adipex free samsung ringtones ativan online xenical online cheap propecia cheap wellbutrin celexa online hgh online didrex wellbutrin online alprazolam free ringtones hydrocodone online free midi ringtones free mp3 ringtones free cool ringtones free sony ringtones real ringtones cheap cialis cheap xenical nextel ringtones cool ringtones free sharp ringtones free nokia ringtones norco online lorazepam online mp3 ringtones ambien online sprint ringtones cheap levitra carisoprodol online fioricet cheap prozac diazepam online cheap clomid order zanaflex cheap hoodia free mono ringtones cheap xanax cheap phentermine free real ringtones polyphonic ringtones cheap zyban viagra online carisoprodol online cheap ultracet free kyocera ringtones cheap cyclobenzaprine vicodin online cheap meridia cheap nexium cheap ambien free funny ringtones norco online free mp3 ringtones flexeril cheap diazepam cheap cyclobenzaprine hgh online sagem ringtones buy wellbutrin fioricet online cheap hydrocodone carisoprodol online norco online free tracfone ringtones midi ringtones free sagem ringtones lortab free mono ringtones free mtv ringtones cheap xenical tracfone ringtones but clomid cheap soma cheap vigrx ativan online free ericsson ringtones nexium online cheap lorazepam cialis alltel ringtones free wwe ringtones levitra online tenuate online celexa online online pharmacy online cheap diethylpropion free ringtones buy alprazolam free motorola ringtones alltel ringtones paxil online zyban online cheap cyclobenzaprine propecia online free qwest ringtones funny ringtones free motorola ringtones cheap xanax free nextel ringtones cheap clonazepam meridia cingular ringtones buy alprazolam order flexeril cheap adipex cheap phentermine vigrx online sildenafil online verizon ringtones polyphonic ringtones jazz ringtones free tracfone ringtones buy pharmacy online free nextel ringtones valium online buy clonazepam order valium prozac online cialis online hoodia online cheap lisinopril cheap ativan tramadol free sony ericsson ringtones buy valium albuterol online free verizon ringtones free sharp ringtones free sonyericsson ringtones free samsung ringtones cheap vicodin viagra online free samsung ringtones order levitra but lipitor tramadol online nokia ringtones cheap albuterol mtv ringtones cheap phentermine free qwest ringtones real ringtones cheap meridia didrex online diethylpropion online free sprint ringtones cheap xanax free ringtones didrex online jazz ringtones ortho online online paxil cheap soma buy lorazepam free ericsson ringtones ultracet online qwest ringtones buy soma buy ultram buy rivotril fioricet online buy tenuate free nokia ringtones free sonyericsson ringtones free motorola ringtones sildenafil online viagra online free sony ericsson ringtones nexium online zoloft online funny ringtones buy ambien cheap hydrocodone ortho online free cingular ringtones lisinopril online cheap zanaflex ultram online cheap vicodin order ultracet free punk ringtones cheap clonazepam lortab online free wwe ringtones music ringtones order adipex free punk ringtones order lipitor buy diazepam cheap propecia free music ringtones online rivotril ultram online online zoloft cheap tramadol cheap paxil free sony ringtones There are many kinds of motor drivers:
- servo motor controller
- stepper motor controller
- DC motor controller ("brushed")
- AC motor controller ("brushless")
- ... (todo: fill in the other kinds) ...
A DC motor controller that is 'reversable' generally uses an 'H bridge'. This 'H-bridge' uses four output drivers in a configuration that resembles an H where the load is the cross bar in the middle. The lines on either side of the load (the downward strokes in the H) represent a series connection of a pull-up driver and a pull-down driver. This allows each terminal of the load to be connected to either the positive supply rail, or the negative supply rail. This allows a positive, negative or zero voltage difference across the load. This load voltage is then utilised to provide the desired control required of the motor. The various combinations can give a 'forwards' torque on a DC motor, a 'backwards' torque on the same motor, can allow the motor to free-wheel (without any applied torque) or can provide a locking of the motor such that it resists any attempt to rotate it.
A single phase AC motor is generally driven in the same way as a DC motor, however instead of operating the motor drive as a constant DC voltage (in either the 'forward' or 'reverse' direction) the AC motor is driven by an approximation to a sinewave. This approximation is created using the H bridge and driving it with a PWM input such that both the positive and negative voltage periods are the same. This is normally acheived either using a sawtooth waveform compared against a sine wave reference, or is done using a lookup table in a microcontroller.
A similar method is used to drive multiphase (3-phase) AC motors, however instead of just using an H bridge, only a half H bridge is used per phase. Each phases half bridge is then driven in the same manner as for the single phase motor, with a phase difference between the phases as appropriate.
((fill in more details here...))
Some motor controller circuits are such that, if the software accidentally sets the "wrong" pins hi or lo, you get a short circuit through the output drivers. This will generally cause a high current to flow, due to the low on state resistance of the output drivers, which may destroy other electronic components before finally blowing the supply fuse.
Other motor controller circuits are such that, if the software accidentally sets the "wrong" pins hi or lo, the worst that could happen is the motor spins the wrong way. These circuits are designed so that, no matter what the inputs, it is impossible to get a short circuit through the output drivers. Between "one branch on" and "the other branch on", there is a minimum "blanking time" which has "both branches off". This guarantees that we never have "both branches on" (short circuit).
Guess which type of design I prefer?
A random collection of semi-related links (please prune out the irrelevant ones):
- H-Bridge by Bob Blick
- the Open Source Motor Controller Project
- LiniStepper $30 each; Open Source! Circuit Diagram, PCB (Board) Layout, and PIC Software all available
- H-Bridge Fundamentals An in-depth article on the design of Mosfet H-Bridges
- PMinMO.com Open Source circuits and information on stepper motor controllers]
- ePanorama ePanorama Motor Control page
- "Electronic Design of DC Motor Drives" has detailed schematics and PCB layout for a system that has a PC send commands through the serial port to a Microchip PICmicro, which does PWM control of 2 H bridges. Each half-bridge uses a IRF9530N (100V 14A pfet plus flyback diode) and a IRF530 (IRF530NPBF: 100V 17A nfet plus flyback diode), driven by a small transistor inverter based on a BD135 npn, for a total of 12 discrete transistors.
Robots use motor drivers.
