12V DC Motor Is Working with Stable Voltage on One Polarity, While Voltage Fluctuates and Motor Stal

12V DC Motor is working with stable voltage on one polarity, while voltage fluctuates and motor stalls on other polarity. What have I done wrong in rewinding the motor?What was the motor originally designed for? Some brushed DC motors have their brushes optimized to spin better in one direction. You might see this listed as "brush advance" or "distortion compensation".

1. Can a DC motor run at 12V 10amps?

Yes, if it is a 12v DC motor that draws 10 amps....sj

2. run a 6V DC motor with 12v DC power source?

Go for the 7.5 volt option, the burn out issue will only arise if the motor is used for long periods. You are drilling small holes so the duty cycle is likely to be low, just keep an eye on the motor temperature

3. Arduino serial communication fails when stalling/loading a DC motor controlled by PWM

It seems like it might be a ground issue of some kind. What are your power supplies, and how are they connected? Did you do the circuit on a breadboard like the picture in the link?When you heavily load or stall the motor, it will pass significant current. Assuming you built it like the picture, a large current in your motor power return lead could cause the (-) rail on the breadboard to ride up. If the motor p. s. is referenced back to the PC's ground (beware the 'sneak path'!), this could cause the apparent voltage levels at the USB interface to be out of spec. You might even get some kind of latch-up effect that would require removal of power.If your motor p.s. is not a battery, you might want to try using a battery, and see if the condition persists.

4. Is it possible to control the speed of a DC motor with a potentiometer?

Yes, it is possible and very simple to do. Place your pot inline on the voltage line going to the motor. As you turn the pot, the current drops and the motor spins slower. The size of the motor is no matter. Not efficient is an understatement... Have fun and try it!

5. Long shunt DC motor speed control characteristics?

DC motor speed control does not normally use series, shunt compound or any other connection of the field to the same supply as the armature. The controller provides a separate regulated power supply for the field. The field current is maintained at a constant value unless field weakening is used to extend the operating speed above the normal base speed of the motor. There might be some other configurations used in special circumstances.The term "variable torque" is usually applied to loads that have a torque requirement that is low at low speed and increases with speed. Fans and centrifugal pumps have that characteristic. DC motors are not used for such applications except when battery operated. In that case a permanent magnet motor would be preferable

6. Does the frequency of a PWM signal have to be constant for a DC motor/fan speed control?

The frequency need not be constant, although it often ends up this way because it's easy to implement. One reason to vary the frequency is to spread EMI and audible noise across the spectrum. It's also possible to perform motor control by hysteresis. Or, the pulse width may be held constant but the frequency varied. Or, both may be varied.What is really important is average voltage being applied to the motor over time. In the case of a simple DC drive, the average voltage is the same as the voltage applied at any instant. Usually, the voltage switches between 0 and the supply voltage $Vcc$, so the average voltage will be somewhere between 0 and $V_cc$, according to the proportion of time spent on $t_on$ in some period $t_total$:$$ V_avg = V_cc fract_ont_total $$So if over $100mS$, you spent a total of $40ms$ on, and $V_cc$ is $12V$, then:$$ V_avg = 12V frac40ms100ms = 4.8V $$So, to the extent that the inductance of the motor is able to average the current over $100ms$, you might as well have been applying $4.8V$ DC to the motor.This is what sets the lower bound on the drive frequency. If the frequency is too low, the current in the motor windings (and thus, the torque, and thus, the speed) will not be constant. Take an extreme case: you apply 12V for 4 minutes, then 0V for 6 minutes. The average voltage is still 4.8V, but obviously you do not get the same effect. As the frequency becomes higher, the maximum current (right before switching to the off state) and the minimum current (right before switching to the on state) will not be very different, and the motor current is mostly constant. This is because the rate of change of current $I$ in an inductance $L$ is limited by the applied voltage $V$:$$ V = LfracmathrmdImathrmdt$$or equivalently:$$ fracmathrmdImathrmdt = fracVL$$Your power supply can apply only a finite voltage to the motor windings (an inductor), so the current can only change so fast. Switch fast enough, and the current never has time to change significantly. Another way to think of this: The current in the motor will have some DC component, the average value that spins the motor in the desired direction. It will also have some AC ripple added to that, which just makes heat in the windings since it spends half its time spinning the motor in the desired direction, and the other half in the wrong direction. Your goal, in designing a PWM motor drive, is to reduce the current ripple, and the consequent wasted electrical energy, as much as possible, without increasing other losses in the system. Another requirement is often that the motor not make audible noise, and this often requires that the switching frequency be above the limits of human hearing, about $25kHz$.The upper bound on switching frequency is set by losses that increase with frequency, primarily switching losses. Transistors can not switch instantly, and so will necessarily spend some time with both significant current in them, and significant voltage across them, thus converting electrical energy into heat ($P=IE$) each time they switch. As the frequency is raised, the number of switches per second increases, but the time spent transitioning from on to off states says the same, so the average power in the transistor increases until the heat destroys the transistor or the driver efficiency becomes unacceptable

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Shunt DC Motor Controller Improvement
Shunt DC motor controller improvementSo this looks as if the circuit controls armature current?It controls armature voltage.would it be better if the winding current was controlled?Controlling armature current with an outer voltage or speed control loop would be better, but more complex.By "winding current" I suspect you mean field winding current as apposed to armature winding current. Controlling the field winding current would make the minimum operating speed about equivalent to the present maximum speed. Reducing the field current will increase the speed and reduce the torque capability. I doubt very much that is what you want.The above seem to be the only actual questions asked. The question seems to imply that you wish to improve the control scheme because the motor " runs slightly erratically." You have not actually described what aspect of motor performance is undesirable.Speed decrease with increased load is normal for a simple armature voltage control. Random speed variation with a steady load could be due to line voltage variation, other power quality issues, motor brush problems or a loose connection. Failure to start relably would like be a brush problem— — — — — —Can you use an AC switch with a DC motor?Just follow the ratings of the switch. Typically, the DC voltage rating is less than the AC voltage rating. Current ratings are normally the same— — — — — —What is an interpole in a DC motor?Thanks for A2A.Purpose of Interpole in DC MachineFor understanding the role of Interpoles, we need to understand the effect of armature reaction in the DC Machine. The effect of armature mmf on the main field flux is to distort the main field flux and to reduce the net main field flux. The figure below, shows the effect of armature mmf on the main field flux. It is quite clear from the above figure that the flux at the location of Carbon Brush i.e. A, B and A are not zero and therefore an EMF will be induced in the coils undergoing commutation and will lead to the sparking. As we know that for better commutation, the coils short circuited by the brushes should have zero EMF induced in them. As the zero crossing of field flux is shifted due to armature reaction, the coils undergoing the commutation will have a net EMF induced in them. This induced EMF in the short circuited coil will delay the reversal of current in the short circuited coils and will result into poor commutation and sparking at the carbon brushes.The question arises how to resolve this issue?If we see the figure above, we observe that there is a net shift of zero crossing of net flux in the air gap by an angle Ɵ in the direction of rotation for Generator and opposite to the direction of rotation for Motor. So the cheap and easy solution shall be to shift the Carbon Brush at Zero Crossing of the air gap flux.Thus carbon Brush need to be shifted by an angle Ɵ from Geometrical Neutral Axis (GNA) in the direction of rotation for Generator and opposite to the direction of rotation for Motor.But this method of shifting the Carbon brush has a big disadvantage. What is that?As the Armature Reaction depends on the current flowing through the armature winding which in turn depends on the load current. Therefore as the loading of the DC Machine varies the angle Ɵ will also vary and therefore we need to continuously shift the Carbon Brushes. So we need to find a smart way.Again, looking back to the figure, if it could be possible to make the resultant or net air gap flux zero at GNA, then there would not have been any detrimental effect of armature reaction on commutation. Also, the existing flux at the GNA (at point C) is due to North Pole so we could use a South Pole (opposite of the pole which produced the imbalance at C) at C so that the net flux at C becomes Zero. Similarly at C' we can use a North Pole to make net flux Zero there. Okay, this will work fine but how t change the magnitude field strength of this newly installed poles at C and C'? Hmmmm. .We can use a winding on the newly installed poles at C and C' and connect that winding in series with armature winding so that the strength of field due to newly installed poles at C and C' varies proportionally will the loading of machine. Yes, this will work fine.So we can conclude our solution as,We will use Poles same as that of Main Poles ahead of GNA or Carbon Brush for Generator at the location of GNA or Carbon Brush and Poles same as Main Pole that of behind the GNA or carbon Brush for Motor at the location of GNA or Carbon Brush and will use winding on them and connect them in series with the armature winding as shown in figure below.The Poles used in our smart solution is called the Interpole. Interpoles are narrow poles placed at the GNA and fitted to the Yoke and also known as Commutating Poles or Compoles. For generator, the polarity of Interpoles must be same as that of main Pole ahead of it in the direction of rotation. For Motor, the polarity of Interpole must be same as that of Main Pole behind it. So I expect that you understand the purpose of Interpoles as you only designed it. But there is one more interesting role of Interpole.Interpole do not only nullify the effect of armature reaction but in addition, produces some extra mmf in the interpolar zone. This extra mmf in the interpolar zone induces rotational EMF in the short circuited coil undergoing commutation in such a direction to oppose the reactance voltage in the coil. Thus the resultant the resultant voltage in the short circuited coil becomes zero and the commutation is spark less.What is an interpole in a DC motor?
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