Figuring Out How Much Torque Dc Motor Will Need to Run at a Certain Speed. (E-skateboard Project) [c

For any powered vehicle the maximum speed on level ground is determined by the sum of the forces resisting its movement. These forces can be roughly broken down into: Typically the first two will be either more or less constant or proportional to speed, air resistance (drag) tends to increase with the square of speed and it is this which is generally the limiting factor on top speed. So if you apply a constant torque to the wheels the vehicle will continue to accelerate untill the accelerating force is equal to the retarding force. The powered wheels convert torque to force with the relationship T = Fr , where T = Torque at the wheel axle, F = Force and r = wheel radius. This page details how to estimate drag forces and provides a coefficient for a standing person. To estimate friction forces a simple method is to load up the board with the approriate weight and uses a spring balanc to determine the force required to just get it moving, this is a bit crude but should give you a ballpark estimate. In terms of selecting a motor you will need to consult the torque curve for the motor which describes teh relationship between torque and RPM will also influence what overall gear ratio you need. Of course maximum speed is no the only thing you need to consider you also need enough torque to provide adequate acceleration and hill-climbing as well as taking bulk, weight and your power supply into account

1. Calculating omega (ω) in a separately excited DC motor

The applied field voltage for a separately excited motor is held constant while Va is changed. So you can use If = Vf/Rf to calculate flux. Then use the equation for torque in terms of flux and Ia to calculate Ia in terms of torque and flux. Substitute that for Ia in the equation for omega in terms of Torque and Va. Divide the torque terms in the numerator by the torque in the denominator and the equation for omega will be in the desired form

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

This sounds like a home work question. PWM (for anny application) is usually a fixed period because it's easiest to implement in hardware (It does not have to be fixed). You set values (in a MCU or the hardwired circuit) and forget. Any maths is to do with the implimentation regarding period, counters, minimum and maximum duty cycles, filtering of the output by a RC network to calculate a DC output and it's ripple if required

3. Why would I need a relay between a DC motor and my Arduino?

Firstly, a motor is a very power hungry device. An Arduino IO pin can only provide an absolute maximum of 40mA from an IO pin, and Atmel do not guarantee anything over 20mA. A motor typically takes considerably more than that, especially during it's acceleration phase. Powering a motor direct from an IO pin is not only a Bad Idea but is also doomed to failure from the outset.So you need something to provide more current to the motor, and that means some form of external switch.Yes, you can use a relay as that switch, however a relay also suffers the same problems as a motor - they are generally quite power hungry, and need some form of external switch to allow the Arduino to drive them. Yes, you can get relays that are weak enough for an Arduino to drive direct, and you can get relays with built in switching circuits, but in general most relays are too powerful for a mere Arduino to switch.So you need another option, and that option is a transistor.Secondly, motors (and relays) are very noisy devices. Regardless of the amount of current required to drive them, they will be creating lots and lots of voltage spikes, both positive and negative, on their connections. You really do not want those spikes going into your Arduino an making the Magic Smoke escape. So you need to divert them elsewhere. That requires a diode reverse biased across the winding / coil of the motor / relay. Also the transistor you use to drive the motor or relay acts as an extra layer of separation from the Arduino keeping those spikes away.So follow the (millions of examples - ask Google) standard circuits for driving a relay or motor through a transistor from an Arduino and you will be safe

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Shunt DC Motor Controller Improvement
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?
How Can I Calculate DC Motor Continuous Current?
How Can I Calculate DC Motor Continuous Current?
Continuous rated current is the current the motor can continuously run at for a given voltage such that the temperature of the motor windings doesn't exceed the rated temperature of the insulation class of that motor. Here is how you would test for the continuous rated current. There is no good way to calculate this unless you are prepared to model the motor both electromagnetically and thermally. For a well designed DC motor, a general rule of thumb is that the continuous rated point will be slightly larger than the maximum efficiency of the motor. Generally this occurs when the speed drops to about 80-90% of the no-load speed. But that is just a rule of thumb.Also, given that your no-load speed is 150 RPM, I'm assuming this is a gearmotor. In this case, it could be the gearbox, not the motor, that is limiting the performance of the gearmotor. Regarding your calculations ... 550 W is listed as the maximum output power. This is usually much bigger than the continuous rated power of the motor (which for this motor appears to be 400 W). Also, you can't say $P_max I_max*V_max$ because $P_max$ is an output and $I_max$ and $V_max$ are inputs. Your real equation would need to be $P_cont I_cont*V*eta_cont$, where $eta_cont$ is the efficiency at the continuous rated point. Plug in what you know: $400 W I_cont*24 V*eta_cont > I_cont frac400 W24 V*eta_cont$For this size motor, you could estimate the efficiency to be 80%. That gives you $I_cont 20.8 A$.Note that the efficiency at maximum power will be closer to 50%, so the current at maximum power will be approximately $frac550 W24 V*0.5 45.8 A$. But these are just estimates. If you are building a motor driver for this motor, you will want to get the actual data from the motor manufacturer. As others have suggested, any good manufacturer will already have this data, so if they can't give it to you easily with just a phone call or email to them, then I would suggest finding a new motor.I have some information for a brushed DC motor:Nominal voltage: 24 VOmic measure: 16 ohmsPower: 400 WMaximum output power: 550 WRev: 150 RPM (no load)Test voltage: 26.0 V (no load)Current: 2.5 A (no load)Now, I'm trying to find the right motor driver and I have to calculate continuous current of motor, but I'm not sure how to do it. Here's my attempt:$$P_max I_max cdot V_max$$$$550W I_max cdot 24V$$$$I_max 22.9 A$$Is my calculations correct? If not, how can I calculate the current properly?·OTHER ANSWER:I have some information for a brushed DC motor:Nominal voltage: 24 VOmic measure: 16 ohmsPower: 400 WMaximum output power: 550 WRev: 150 RPM (no load)Test voltage: 26.0 V (no load)Current: 2.5 A (no load)Now, I'm trying to find the right motor driver and I have to calculate continuous current of motor, but I'm not sure how to do it. Here's my attempt:$$P_max I_max cdot V_max$$$$550W I_max cdot 24V$$$$I_max 22.9 A$$Is my calculations correct? If not, how can I calculate the current properly?
How to Use Raspberry Pie to Control DC Motor
By successfully controlling the DC motor using raspberry PI, we can use it for a variety of other applications, such as robots, remote control (RC) cars, fans and other related motors. The purpose of this project is to safely connect the motor to raspberry PI and control it, even if it rotates forward or backward.Note: I will use motor drives in this project, which can handle up to two motors. Therefore, two motors can be controlled separately.Before continuing with this project, learn how to set up raspberry PI and keyboard without monitorworking principleThe main principle of using raspberry pi to control DC motor is motor driver. Motor driver is a special circuit or IC, which can provide the necessary power supply (or more accurately, current) for the motor to achieve smooth and safe operation.Even small 5V DC motors can have an initial current of about 300 - 400 ma. When the motor accelerates to approximately, the current will drop 150 - 200 ma.This is a huge trend for microcontrollers, Arduino, raspberry PI and other devices. Therefore, we should not connect the motor directly to the raspberry PI (or any other microcontroller).The motor driver plays an important role in this case. They obtain the control signal from raspberry PI and provide the necessary driving current for the motor through the power supply.In this project, the motor driver (L293D) has two signals from raspberry PI controlled through GPIO pin. According to the python program, the motor will rotate in the forward or reverse direction.Circuit diagramFritzing ImageAs I said before, using the L293D motor driver IC, we can actually control two motors. For simplicity, I will demonstrate the circuit, operation and program of using raspberry pi to control a single DC motor. The following figure is the fritzing diagram of the project.Circuit diagramThe circuit wiring diagram of the project is shown below. You can easily configure this circuit and the program to control two DC motors using raspberry PI and L293D motor driver IC.Required componentsRaspberry PI 3 type BL293D motor driver IC or moduleSmall DC motor (5V)Connecting wire (jumper)5V - 2A power supply for raspberry pi5V power supply for motorOther (computer, Ethernet) cables, etc.)Brief description of L293D motor driver ICI use the L293D motor driver IC to control the DC motor with raspberry PI. It is a very common motor driver IC, which can drive two motors with a single current of up to 600mA.The pin diagram and pin description of L293D motor driver IC are shown in the figure below.circuit designThe circuit design of using raspberry pi to control DC motor is very simple. First, connect pins 8 and 16 (VCC2 and VCC1) of L293D to an external 5V power supply (assuming you are using a 5V motor).There are four ground pins on the L293D. Connect pin 4 to GND of the power supply. In addition, connect the ground pin of L293D to the GND pin of raspberry PI.Finally, we have enable and control input pins. Connect pin 1 of L293D (1, 2EN) to gpio25 (physical pin 22) of raspberry PI. Then, control input pins 2 and 7 (1a and 2A) are connected to gpio24 (physical pin 18) and gpio23 (physical pin 16), respectively.Optional: if you want to connect the second motor, you need to connect the enable (3, 4En) and the second motor control input (3a and 4a) to the three different GPIO pins of raspberry PI.Also read this simple project: how to flash LEDs using raspberry PI and pythonPython program uses raspberry pi to control DC motorProject work and code descriptionHow to operate the project?Before turning on the power supply, ensure that all connections related to the motor, power supply and raspberry PI are correct. For programming, I'll use python.Now open the terminal in raspberry PI and create a new Python file "dcmotorpi. Py" command using VIM editor and the following.sudo vim dcmotorPi.pyCopy and paste the above program into the editor and save the file. Note: I have saved a python program named Python on the raspberry PI desktop_ Progs folder. Now, in order to run the program, enter the following command in the terminal.sudo python dcmotorPi.pyThe motor will now rotate forward for 3 seconds, then reverse for 3 seconds and finally stop. After a few seconds, the process will continue until crtl C is pressed in the terminal.Code descriptionYou can easily understand this code if you have followed my previous project on how to use raspberry pi to flash LEDs and connect 16 x 2 LCD using raspberry PI.First, we need to use Python to access the GPIO pin. Therefore, we need to import the module rpi.gpio into our program. Similarly, the module time allows us to use its function sleep pause program for a predefined period of time.Now, I have assigned pins (enable and two control inputs) to the L293D motor driver IC. In addition, the pin mode is set to GPIO number format.Now, all pins are declared as outputs. During forward rotation, the enable pin becomes high, the control input 1A becomes high, and the other control input 1b becomes low.After a delay of three seconds, control input 1A becomes low and control input 1b becomes high, while keeping the enable pin high. This will reverse the rotation of the motor.Finally, after a delay of three seconds, the motor will stop rotating and stop. Repeat this process until we press Ctrl C in the terminalapplication programDC motors can be seen everywhere: robots, unmanned aircraft, remote control vehicles, etc. By using raspberry pi to control DC motors, we can use raspberry pi to develop many motor related projects.It can be used in robot applications based on raspberry PI, such as line following robot, obstacle avoidance robot, four axis aircraft, network control robot, etc.
Zero Crossing Events with Brushless DC Motors
Each of the three Hall Effect sensor signals is out of phase with the others by 120. The same is true for the BEMF signals. The Hall Effect signals and the BEMF signals are 30 out of phase with each other.From this Microchip App note:Hall sensor signals are out of phase by 120 degrees to each other. At every 60 degrees, one of the Hall sensors makes a transition.The BEMF generated in the windings are also at 120 degrees out of phase to each other, but they are asynchronous with the Hall sensor signals. In every energizing sequence, two phases are connected across the power supply and the third winding is left open. the BEMF voltage is monitored on the winding that is left open. With this, the BEMF voltage in windings increases when it is connected to power supply and reduces when it is connected to the return path. The transition takes place when the winding is left open in the sequence. The combination of all 3 zero cross over points are used to generate energizing sequence. The phase difference between the hall sensor and the BEMF signal is 30 degrees.So if you commutate 30 after sensing a zero crossing, you are actually commutating at the same time you would be if you detected a change in the Hall Effect sensors.The reason the Hall Effect signals and the BEMF are out of phase is because they are measuring two different things. The Hall Effect sensors are measuring rotor position. The BEMF signals are measuring stator sequence energization. It is from that energization that we can extrapolate rotor position and determine correct commutation timing.From this Atmel App note:The optimum drive sequence is to drive PWM at 30 after zero crossing to be in phase with the rotor position as shown by the figure below. Driving earlier or later to this 30 will increase the current comsumption sic of the motor.So why 30? 30 is the amount of time it takes for the interaction between the stator magnetic field and the rotor magnetic field to begin to weaken to the point that stator's electrical field needs to be altered in order to strengthen the interaction between the two magnetic fields.You can actually play with this timing to some degree by doing things like rotating the Hall Effect sensors in order to achieve certain results and/or meet certain requirements. I go into this practice more in my answer to this question: Why Have Non-Zero Timing on a BLDC?.I would like to ask a question about zero crossing event in a trapezoidal commutation on a brush-less DC motor. Here is a waveform that shows that the zero crossing event occurs every 180 electrical degrees in a sinusoidal commutation:But what about trapezoidal commutation. Here is the waveform that I found about the trapezoidal commutation:So as you see, the zero crossing occurs 30 electrical degrees after the previous commutation and 30 electrical degrees before the next commutation.In a motor with one pole pair, we would have 30 electrical degrees 30 mechanical degrees, so we would have this waveform:You see that the zero crossing in phase A occurs when the magnet faces the phase C, or in other words, after 30 electrical degrees from the last commutation.My question in why does the zero crossing happen at that moment, why not after 60 electrical degrees, or 15 electrical degrees?Is it related to some law's of induction? What are those law and how do this law's appear in this motor?Can someone explain to me this with some pics?·OTHER ANSWER:I would like to ask a question about zero crossing event in a trapezoidal commutation on a brush-less DC motor. Here is a waveform that shows that the zero crossing event occurs every 180 electrical degrees in a sinusoidal commutation:But what about trapezoidal commutation. Here is the waveform that I found about the trapezoidal commutation:So as you see, the zero crossing occurs 30 electrical degrees after the previous commutation and 30 electrical degrees before the next commutation.In a motor with one pole pair, we would have 30 electrical degrees 30 mechanical degrees, so we would have this waveform:You see that the zero crossing in phase A occurs when the magnet faces the phase C, or in other words, after 30 electrical degrees from the last commutation.My question in why does the zero crossing happen at that moment, why not after 60 electrical degrees, or 15 electrical degrees?Is it related to some law's of induction? What are those law and how do this law's appear in this motor?Can someone explain to me this with some pics?
Cause Analysis and Solution of Permanent Magnet DC Motor Noise
The noise emitted by household electrical appliances generally does not cause hearing damage to users and other participants, but it will more or less cause discomfort to users. Now household electrical appliances are pursuing the era of silence, so the decibel requirements for products are becoming more and more strict, and manufacturers are also becoming more and more strict in selecting spare parts. So how should we control the noise of permanent magnet DC motor? Next, we introduce the method of controlling motor noise through experiments:Practical examples:Permanent magnet DC motor d5373Operating speed: 3700rpmWorking voltage: 220VProblem Description: the noise value is too large, reaching 61db (a), exceeding the specification requirements, 55dB (a)Problem analysis: the noise value of permanent magnet DC motor is too large, so first test the vibration and noise under the working state of the motor, make spectrum analysis, and preliminarily analyze the possible causes of exceeding the standard of motor noise.Move the microphone to a place 15cm away from the motor housing, test the noise of the motor, and conduct spectrum analysis. The results are as followsWhen measuring noise, stick the acceleration sensor on the housing and test the vibration of the motor housing.The rotating speed of this permanent magnet DC motor is about 3700rpm / min, and its fundamental frequency is about 52hz. From the above motor vibration and noise test results, it can be seen that the vibration and noise spectrum of the motor is about 1200Hz, 2400hz and 3600Hz, and there are obvious peaks in the accessories. Since the number of rotor core slots of the motor is 24, it can be preliminarily analyzed that the vibration and noise of 1200Hz are caused by radial force wave, In other words, it is caused by the torque ripple of the rain rotor, and the vibration and noise of 2400hz and 3600Hz are twice and three times the frequency respectivelyTheoretical analysis and practice have proved that the inclined slots and poles of the stator and rotor of the permanent magnet DC motor can make the radial force wave phase shift along the axis of the motor length direction, so the average radial force along the axis is reduced, so as to reduce the vibration and noise of the motor. For the permanent magnet DC motor d5373 in this practical example, The scheme of rotor core chute can be adopted to reduce its vibration noise. After adopting the inclined slot, the noise of the motor is fully reduced by 10dB (a), so the noise reduction effect of adopting the rotor core inclined slot can be established.
What Is the Definition of Kv Value of Brushless DC Motor? Is the Kv Value the Greater the Better?
Brushless DC motorFirst, people will master what is called the Kv value of DC brushless motor: the Kv value of DC brushless motor is different. The low value is 1000-2000 and the high value is 5000-6000. It expresses the standard value of the speed ratio for each rise of working voltage by 1 volt. For DC brushless motor, this value is a constant.For the DC brushless motor with the same specification and size, if the winding coil has more turns, the Kv value is low, and the high output current is small, but the torque is large. If the winding coil has less turns, the kV is high, and the high output current is large, but the torque is small.Of course, the quality of the motor cannot be judged by the kilovolt value, because different kilovolt values have different applications.It is assumed that the natural environment of DC brushless motor is 7.1v, and the Kv value is low. Because the speed ratio is slightly low, it is suitable to be equipped with small transmission ratio and large aircraft propeller. It depends on a large load to increase the current and output a large output power. KV is too high. Because the speed is relatively high, it is suitable to be equipped with large transmission ratio and small aircraft propeller. Under the condition of considering the output power, reduce the load and avoid excessive current.Assuming that the high voltage natural environment of DC brushless motor is 11.9v and the Kv value is low, it can achieve high speed ratio and very good torque under this natural environment of working voltage. It is ideal. It must cooperate with large transmission ratio and small aircraft propeller. Under the standard of power, it is necessary to reduce the load and prevent excessive current. If kV is high, the transfer speed ratio is too high in this natural environment. In order to prevent excessive current, try to avoid load and use its high-speed rotation. It is very suitable for culvert fan diesel engine.Of course, users can provide the required Kv value to Donghong Electromechanical, and we will recommend a suitable DC brushless motor to you.
PWM Speed Control of High Power Brushless DC Motor Based on 51 Single Chip Microcomputer
Recently, I have always wanted to use 51 single chip microcomputer to design and make a "PWM speed controller for high-power DC brush motor". I have no time because of my busy work. So it took me a long time. Every night after work, I do it when I get home. I don't rest until eleven or twelve o'clock. During this period, I also spent a lot of money and failed n times. Finally, Kung Fu pays off. I finally succeeded, ha ha .Because this is a high-power DC brush motor PWM speed controller, it can not be driven by transistors, but must be driven by MOS transistors. MOS transistor not only has strong driving ability, but also has high efficiency. In order to improve the stability, reliability and wide application range of the system, the system adopts dual power supply. The control circuit consists of a group of power supplies with voltages of 5V and 15V respectively. The power output part is a group of power supplies to adapt to motors with different voltages. As for the power, it can be determined by paralleling the MOS tube according to the actual situation, but at the same time, the relevant parameters of the lower drive circuit should be modified, otherwise it is likely to explode the MOS tube! In addition, I have also considered connecting the PWM pulse output end of the single chip microcomputer with the driving circuit through an optocoupler to realize photoelectric isolation and improve the stability of the system. But later, I was worried that the frequency response rate of the optocoupler might bring factors such as signal attenuation or wrong signal to the driving circuit, resulting in reducing the efficiency of the system or damaging the MOS tube. Maybe I'm worried too much. Hehe, but I see that a lot of information on the Internet is photoelectric isolation.At present, this version of the speed controller has 4 PWM pulse outputs, which are respectively provided to the forward rotation signals of the upper and lower MOS tube drive circuits. The driving circuit of upper and lower MOS tubes reverses the signal. In standby mode, a red LED light flashes, indicating various states of motor operation. It can operate in three gears: low speed, medium speed and high speed. It can also realize the functions of braking and reversing. At present, it can reach at least 100W, which is no problem. I now use a 12V 80W DC brush motor. The voltage is 3.7V at low speed, 6.5V at medium speed and 10.5V at high speed. At present, this Dongdong only realizes the most basic control function. It does not have other functions, such as motor overcurrent protection, undervoltage protection (this function can be used when the battery is used as the power supply to protect the battery from over discharge), etc. These functions will be studied and realized slowly in the future. ha-ha. No more. Look at the photos. The program source code can be downloaded from here: I hope you will give me some advice.
Application of Permanent Magnet Materials in Permanent Magnet Brushless DC Motor
Injection molding, bonding and sintering have different manufacturing methods, performance parameters and application characteristics.Their performance is increasing, and so is the price, which determines their respective applications. Injection molding permanent magnet materials can be divided into injection molding ferrite and injection molding neodymium iron boron. Its adhesives include nylon 6, 12 and PPS. Nylon is slightly cheaper than PPS, but its surface finish, strength and temperature resistance are worse than PPS.Their common feature is that they can be injected with various parts or shafts to ensure the quality of products. Injection molded ferrite magnets are divided into isotropic (equal directivity) and anisotropic (different directivity). The isotropic magnetic energy product is low, about 12kj / m3, and the anisotropic magnetic energy product is about 16.8kj/m3.It is mainly used for products with large quantity and wide range, such as brushless DC fan, etc. The maximum magnetic energy product of injection molding Nd-Fe-B is about 48km3, and the high can reach 52kj / m3, but the price is high. At present, the application of injection molded NdFeB can replace some bonded NdFeB magnets with low magnetic energy product, such as injection molded rotor with shaft.Bonded NdFeB is the most widely used in high-performance products. Its performance and price are between sintered NdFeB and ferrite. Moreover, it is isotropic and suitable for various multipole magnetization methods.Its disadvantage is poor temperature resistance, up to 150 ℃, which determines that it is only suitable for small motors. Sintered NdFeB is widely used because of its high performance, but it is mainly used in DC brushless motor and AC Hefu motor, and mainly in tile shape. Because the current sintered Nd-Fe-B is mainly unidirectional orientation, that is, the magnet can only be magnetized in one direction, so it can not be made into a magnetic ring for magnetization of more than 2 poles.The radial oriented sintered Nd-Fe-B has been developed, but the die of radial products is more complex and the cost is slightly higher. Radially oriented sintered Nd-Fe-B magnetic ring will first be applied in DC brushless motor and AC servo motor. Using radial orientation, the waveform after magnetization is close to rectangular wave rather than saddle shape.At present, injection molding and bonding NdFeB can be used for multipole magnetization of magnetic ring. Multipole magnetization of magnetic ring can be divided into external charging of magnetic ring and internal charging of magnetic ring. The external charging of the magnetic ring means that the outer surface of the magnetic ring is filled with magnetic poles, which is generally used for inner rotor motors; The inner filling of the magnetic ring means that the inner surface of the magnetic ring is filled with magnetic poles, which is generally used for external rotor motors. Multipole motors use ferrite or sintered Nd-Fe-B, and multipole rotors are often formed by assembling multiple magnetic plates. At present, multipole magnetization of sintered ferrite magnetic ring can be realized.
What Are the Methods to Change the Speed of Micro DC Motor?
The micro motor manufacturer Shunli motor will introduce the method of changing the speed of micro DC motor:Method 1. Changing the main magnetic flux of the motor can only weaken the magnetic flux and make the motor change speed upward from the rated speed. It belongs to the constant power speed regulation method, with slow dynamic response. Although it can adjust speed steplessly and smoothly, the speed regulation range is small.Method 2. Change the armature circuit resistance R to adjust the speed by connecting the resistance outside the motor armature. There can only be stage speed regulation, with poor smoothness, soft mechanical characteristics and low efficiency.Method 3: adjust the armature voltage. Changing armature voltage to change speed is a constant torque speed regulation method with fast dynamic response. It is suitable for systems requiring large-scale stepless and smooth speed regulation.This is how to change the speed of micro DC motor. For more information about micro DC motor, please contact the micro motor manufacturer Shunli motor.Shenzhen Shunli Motor Co., Ltd. is a micro motor manufacturer specializing in R & D, production and sales of various micro DC motors, DC reduction motors, gear reduction motors, micro reduction motors, planetary reduction motors, micro DC reduction motors, shaded pole reduction motors and special gearbox motors. Consultation hotline: 0755-29124182. Shunli motor official website:
what is the best time of year for dc motor sales?:2021 best dc motor
Brushless motors are generally more efficient and so can make better use of the limited power available. However you still need to match the motor to the power source and load to get best efficiency. A few basic calculations can tell you what motor specs to look for:- First calculate what rpm the wheels must do to get the speed you want. A 12cm diameter wheel has a circumference of 0.377m. To get 2.5m/s linear velocity it needs to turn at 400rpm.Your motor has a Kv of 1400rpm/V, so if powered by 12V it should spin at 12*1400 = 16800rpm without a load. Under load its speed will drop due to voltage lost in the resistance of the windings. Loading depends on a lot of factors such as rolling resistance, aerodynamic drag, bearing friction etc. however assuming you can get the motor running at peak efficiency its speed may drop to 85% of no-load or 14000 rpm. Therefore you need a gearbox ratio of about 14000/400 = 35:1. The 11.5A maximum output current of your solar panels could be a problem with this motor because it draws over 1A just to turn over. Under acceleration it will try to draw even more current, but the solar panel may not be able to supply it so its voltage will drop and the speed controller might cut out. You should use a lower Kv motor that has smaller no-load current, eg. Scorpion SII-2212-885Kv which draws less than 0.5A at 12V. This motor only does about 9000rpm (12V * 885rpm/V * 85%) so for it you would need a 23:1 gearbox.1. How do you put a slip ring commutator in a homemade simple DC motor?You do not need slip rings; you need a commutator, which consists of segments that switch the rotor current flow as it turns. Make one out of a cork forced onto the axle, with coils of bare copper wire threaded through small holes in the cork. Brushes to feed the commutator can be made out of spring brass or other metal.2. Can you control a 12V Solenoid Valve using motor dev kit MCLV-2?Most likely something intended to drive a basic brushed DC motor can drive a solenoid, assuming the driver can output the required voltage at the current the solenoid will draw. However, if this "motor driver" is assuming there will be position feedback signals, like from a brushless DC motor, then it wo not work.Anything called a "motor driver" should be able to scale back the drive level to the motor from the maximum voltage it can put out smoothly to 0. If the motor driver can put out up to 24 V, then running it scaled back to drive a 12 V solenoid should be fine. This is usually done with pulses, where the duty cycle sets the overall drive level. A solenoid will be fine with that kind of drive. However, using a motor driver for a solenoid is gross overkill. If you have a sufficient power supply, which you need for the motor driver anyway, you can drive the solenoid with a simple low side switch and reverse diode. There is no need for the more complicated H-bridge drive configuration the motor driver probably has. The IRLML0030 is a nice little FET for the low side switch in this application as long as your power supply does not exceed 30 V. Its gate can be driven directly from a 5 V digital output3. Identify DC motor parameters using Least Squares EstimatorYou need to find out how the input and output relate in the FREQUENCY space. The transfer function is your frequency model.Here is the equation you should use if you want to fit your data to a first order filter. The input is a voltage you control. The output is the value from the encoder, which you probably have to convert to rotational postion or rotational velocity.What your doing is called system identification, and it's easy to do if you have a model with a low order.So take your data, vary the input perhaps by incrementing the voltage in steps (like 0.5V). Then get the output in rotational velocity. If the motor speed starts to trail off as the voltage gets higher, then a first order transfer function would be great to describe this behavior. Then in matlab, figure;plot( Input, Output) (I think I have the axis right) if you see something that has an amplitude like the picture shown from your data then you are on the right track. (remember the input is volts, the output is rotational velocity.)Now you need to come up with parameters from your low pass filter model. You could start punching values into tf([a],[tau a]) by hand to match your data, or you could use an algorithm. Here is a good tutorial on how to do thisMake sure you pay attention to units, your units will be in volts vs rpm or something like that. If your model does not look like a low pass filter and it has a resonance point, then you need to switch to a higher order model. The motor may respond like a bandpass (it does not turn at low speeds and then has a flat passband and then falls off the more voltage that you put into it) Then you would need to switch to a bandpass transfer function.
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