maybe someone can explain the benefits of no bldc to me. i asked like 10 times on other forum but no one replied..lol this is pasted from another forum we won't mention the name here from dr turbo..he is the head of the propulsion lab for dji...the bold was the way it was originally typed not trying to point out something. there was also a picture of a sine wave
0. 800g/motor recommended thrust.
It goes withoug saying.
1. Ever Higher Slot Fill Factor.
As many of you may know, slot fill factor describes how much copper do you wind into the slots. The higher the fill factor, the higher the torque constant, the lower the stator armature resistency, the higher effeciency you have. For short, slot fill factor is about all, its one of the few parameters in motor design that is positive to all motor performances.
Since E600/3508, we have adapted the single strand winding, though very difficult to handle, it provided a completely new level of slot fill factor that you can achieve. As a result, DJI 3508 keeps the record of slot fill factor in the makert untill now. In E800/3510, we have refined our manufactering process and achieved even higher slot filling factor. The DJI 3510 motor is more efficient than its little brother 3508. One byproduct of the neat winding is that the airflow path is larger than the multiple strand winding, and thus the motor can be better cooled.
3. 345 mm/13.5 inch new rotors, now comes with two different mounting options, both with quick release mechanism.
If you think 13.5 inch rotor is just a magnified 1242 prop, you are wrong. Yes, many players in this market simply scale up or scale down one aerodynamic design to have a full familiy of props, but we are not one of them. The whole rotor is designed from the sketchs to maximize its perfomamce. New carbon fiber compond is used to produce the 13.5 inch rotor, which allows us to keep the chord length short while expanding its wing span and keep its stength, to minimize its momentum of inertial. We know, the acceleration of thurst is as important as the maximium thurst.
The standard self-tightening hub is compatible with E600 3508 motors, E600 users who want to trade high wind stability with longer indurance could try it, but taking their own risk.
As for the second mounting mechanism, please allow me to keep this secret to the end, giving our IP guys enough time to submit the patent.
4. Programmable ESC
Yes, just as we have discussed in earlier post, DJI propulsion system is haunted by ESC firmware compatibility for a while. Becauce we constantly upgrade our motor and our ESC software was written so to optimize a certain motor. This approach brings higher efficiency as well as troubles for our old custmer, who want to use their old ESC to drive the new motor.
This time, we want to solve this problem once and for all. Starting from E800, all DJI propulsion system ESC will be equiped with a data port. Firmwares could be flashed into the ESC as long as the hardware supports it. For example, E800 ESC, namely ESC 620S will be supported as long as the R&D team is here, new algorithm and control strategy could be enjoyed by early customers. When new motors are released, and the hardware of ESC 620S is capable to drive it, we will release a corresponding firmware for it. You could mount the motor and flash the ESC and good to go.
ESC 620S will be pre-loaded with 3508/3510 firmware at the factory. we will also release firmware for 620S to support 2212 and 2312 motor.
5. Integrated LED drive.
Flying a multirotor in low light is always a challange, especially when you only have one flash LED on your ship. The LEDs on phantom demonstrated the assistant of multiple LEDs can do to pilots. ESC 620S for E800 will feature an intergrated three color LED drive and bright external LEDs with cables as spares. Weights only few grams, the LEDs could be plugged into corresponding ports on ESC 620S and then be placed anywhere you prefer, be it under the motor or at the tip of the arm. What is more interesting is that the color of the LED could be programmed.
6. Anti-Spark circut
Many of us have one or two blackened XT60 connector, a few of us even had a bird or two falling off the sky due to the failuer of a oxidized connector. The sparking during the plug in of the battery oxidize the metal in the connector and put our aircraft in danger. The sparking is actually caused by the charging of the capacitors on the ESC. When the capacitor is empty and the battery just gets plugged in, the circut at the battery end is basically equal to a short circut and the current could be huge and cause the sparking and thus the oxidization.
ESC 620S of E800 has a build in anti-spark circut, capacitors are not directly soldered on to the power bus but through an active circut. The trick here is that during the initial charging, a resistor is put in the circut to regulates the maximum current. After the initial charging, MCU will open a MOSFET to bypass the resistor and "plug" the capacitor directly onto the power bus to let it play its role.
From E800 onwards, you need never worry about your blackened or melted connectors.
7. ESC: Closed loop control
Most BLDC ESC use open loop control to handle the RPM. It simply convert your input PWM length to a corresponding voltage and let this voltage to affect the RPM. Higher voltage means higher RPM and lower voltage means lower RPM. This is a simple and effective approach, but it does have its limit, because the semi-linear relation between voltage and RPM is only true when the system reaches its static state. During the acceleration between one speed to aother, this linear relation between RPM and voltage is not valid. For example, one motor has a internal resistance of 100 mOhm, and a KV value of 1000RPM/V. Loaded with one propeller, and the voltage is 6V, the current is about 2A and the RPM is 5800RPM. At 7V, the current is around 2.7A and RPM is about 6730RPM. But when you switch between 6V and 7V, the current will rise to 22A at the switching moment and then gradually (an exponential function) drop to 2.7A. Four motors together could generate a current peak of nearly 90A, way above the safe current of a 2200mAH 20C battery. What is more is that the torque of the motor is not smooth but has an impact on the airframe.
Most ESC has a capacity of controling the voltage at a high frequency, say 2KHz. But most morden flight control system can only provide a much lower frequency control signal, around 400 Hz. This means the control input is not smooth for the ESC and motor, and the senario of the example above does happen a lot. From the ESC point of view, the command it receives is a step function, jumping from one point to another. Here is where the close loop control could jump in. The ESC can actually use its own brain to regulate its current at a much finer pace if a proper algorithm is there and the CPU and sensors could handle it.
ESC 620S for E800 has this capacity. The MCU for this ESC is more powerfull than many flight controllers on the market. Helped with current sensors on board, the ESC could control the current and thus the torque in a closed loop and with a much smart strategy. Now the current peak could be carefully smoothed out and the convergence of the PRM from one point to another can be done much faster. Yes, current peak is removed but the overall speed up is accelerated. The battery gets extra protection and thus can run for more charge circles. The motor is now protected from stall and overheat. And many many more possibilities are created.
Cheers,
Dr. Turbo
8. System diagnosis and real time health monitoring--More than a driver
Thanks to the powerful CPU and sensors as well as the corresponding algorithm, E800 ESC620s could not only drive a motor but also diagnose them and monitor them. Motor parameters such as internal resistance, winding temperature, RPM and current are all monitored, in real time.
If you have a demagnetized motor, your E800 will know it and refuse to start.
If you overheat your motor, your E800 will sound the alarm.
If you have a bad connection between ESC and motor, your E800 will refuse to start, If this happened during flight, it will sound the alarm and record this event in the onboard memory.
If you just flashed your ESC620S from 3510 to 2312 motor and hook it to a new motor, before the first start, the ESC will thoroughly diagnose your motor make sure this is a 2312 and it is healthy.
9. Redundant duplex communication
Just as lvale has guessed, E800 will feature a BUS port to communicate with FC. This enable the ESC and FC to communicate in both directions. There is a traditional PWM channel on E800 too, to make it compatible with nowaday flight controllers on the market. Supported with the right flight controller, these two communication channels will hot back up each other to guarantee reliability.
The duplex communication is a real game changer. Together with our real time diagnosis technologies build in the ESC, It enables the flight controller to have a full awareness of the situation in propulsion system. Now FC could know what the temperature every motors has, how fast every rotor is rotating and whether a turbo charge is neccessary and possible at the moment. If a motor fails, the FC will know it at the first second and switch on the preplanned strategy to cope with it.
The BUS channel will also make the FC to have a full use of the thi-color LEDs driven by the ESC. System status, alarms or simple decorative colors can be displayed by all the LEDs on the your DIY aircraft, just as the phanom.
10
Byebye BLDC
0. 800g/motor recommended thrust.
It goes withoug saying.
1. Ever Higher Slot Fill Factor.
As many of you may know, slot fill factor describes how much copper do you wind into the slots. The higher the fill factor, the higher the torque constant, the lower the stator armature resistency, the higher effeciency you have. For short, slot fill factor is about all, its one of the few parameters in motor design that is positive to all motor performances.
Since E600/3508, we have adapted the single strand winding, though very difficult to handle, it provided a completely new level of slot fill factor that you can achieve. As a result, DJI 3508 keeps the record of slot fill factor in the makert untill now. In E800/3510, we have refined our manufactering process and achieved even higher slot filling factor. The DJI 3510 motor is more efficient than its little brother 3508. One byproduct of the neat winding is that the airflow path is larger than the multiple strand winding, and thus the motor can be better cooled.
3. 345 mm/13.5 inch new rotors, now comes with two different mounting options, both with quick release mechanism.
If you think 13.5 inch rotor is just a magnified 1242 prop, you are wrong. Yes, many players in this market simply scale up or scale down one aerodynamic design to have a full familiy of props, but we are not one of them. The whole rotor is designed from the sketchs to maximize its perfomamce. New carbon fiber compond is used to produce the 13.5 inch rotor, which allows us to keep the chord length short while expanding its wing span and keep its stength, to minimize its momentum of inertial. We know, the acceleration of thurst is as important as the maximium thurst.
The standard self-tightening hub is compatible with E600 3508 motors, E600 users who want to trade high wind stability with longer indurance could try it, but taking their own risk.
As for the second mounting mechanism, please allow me to keep this secret to the end, giving our IP guys enough time to submit the patent.
4. Programmable ESC
Yes, just as we have discussed in earlier post, DJI propulsion system is haunted by ESC firmware compatibility for a while. Becauce we constantly upgrade our motor and our ESC software was written so to optimize a certain motor. This approach brings higher efficiency as well as troubles for our old custmer, who want to use their old ESC to drive the new motor.
This time, we want to solve this problem once and for all. Starting from E800, all DJI propulsion system ESC will be equiped with a data port. Firmwares could be flashed into the ESC as long as the hardware supports it. For example, E800 ESC, namely ESC 620S will be supported as long as the R&D team is here, new algorithm and control strategy could be enjoyed by early customers. When new motors are released, and the hardware of ESC 620S is capable to drive it, we will release a corresponding firmware for it. You could mount the motor and flash the ESC and good to go.
ESC 620S will be pre-loaded with 3508/3510 firmware at the factory. we will also release firmware for 620S to support 2212 and 2312 motor.
5. Integrated LED drive.
Flying a multirotor in low light is always a challange, especially when you only have one flash LED on your ship. The LEDs on phantom demonstrated the assistant of multiple LEDs can do to pilots. ESC 620S for E800 will feature an intergrated three color LED drive and bright external LEDs with cables as spares. Weights only few grams, the LEDs could be plugged into corresponding ports on ESC 620S and then be placed anywhere you prefer, be it under the motor or at the tip of the arm. What is more interesting is that the color of the LED could be programmed.
6. Anti-Spark circut
Many of us have one or two blackened XT60 connector, a few of us even had a bird or two falling off the sky due to the failuer of a oxidized connector. The sparking during the plug in of the battery oxidize the metal in the connector and put our aircraft in danger. The sparking is actually caused by the charging of the capacitors on the ESC. When the capacitor is empty and the battery just gets plugged in, the circut at the battery end is basically equal to a short circut and the current could be huge and cause the sparking and thus the oxidization.
ESC 620S of E800 has a build in anti-spark circut, capacitors are not directly soldered on to the power bus but through an active circut. The trick here is that during the initial charging, a resistor is put in the circut to regulates the maximum current. After the initial charging, MCU will open a MOSFET to bypass the resistor and "plug" the capacitor directly onto the power bus to let it play its role.
From E800 onwards, you need never worry about your blackened or melted connectors.
7. ESC: Closed loop control
Most BLDC ESC use open loop control to handle the RPM. It simply convert your input PWM length to a corresponding voltage and let this voltage to affect the RPM. Higher voltage means higher RPM and lower voltage means lower RPM. This is a simple and effective approach, but it does have its limit, because the semi-linear relation between voltage and RPM is only true when the system reaches its static state. During the acceleration between one speed to aother, this linear relation between RPM and voltage is not valid. For example, one motor has a internal resistance of 100 mOhm, and a KV value of 1000RPM/V. Loaded with one propeller, and the voltage is 6V, the current is about 2A and the RPM is 5800RPM. At 7V, the current is around 2.7A and RPM is about 6730RPM. But when you switch between 6V and 7V, the current will rise to 22A at the switching moment and then gradually (an exponential function) drop to 2.7A. Four motors together could generate a current peak of nearly 90A, way above the safe current of a 2200mAH 20C battery. What is more is that the torque of the motor is not smooth but has an impact on the airframe.
Most ESC has a capacity of controling the voltage at a high frequency, say 2KHz. But most morden flight control system can only provide a much lower frequency control signal, around 400 Hz. This means the control input is not smooth for the ESC and motor, and the senario of the example above does happen a lot. From the ESC point of view, the command it receives is a step function, jumping from one point to another. Here is where the close loop control could jump in. The ESC can actually use its own brain to regulate its current at a much finer pace if a proper algorithm is there and the CPU and sensors could handle it.
ESC 620S for E800 has this capacity. The MCU for this ESC is more powerfull than many flight controllers on the market. Helped with current sensors on board, the ESC could control the current and thus the torque in a closed loop and with a much smart strategy. Now the current peak could be carefully smoothed out and the convergence of the PRM from one point to another can be done much faster. Yes, current peak is removed but the overall speed up is accelerated. The battery gets extra protection and thus can run for more charge circles. The motor is now protected from stall and overheat. And many many more possibilities are created.
Cheers,
Dr. Turbo
8. System diagnosis and real time health monitoring--More than a driver
Thanks to the powerful CPU and sensors as well as the corresponding algorithm, E800 ESC620s could not only drive a motor but also diagnose them and monitor them. Motor parameters such as internal resistance, winding temperature, RPM and current are all monitored, in real time.
If you have a demagnetized motor, your E800 will know it and refuse to start.
If you overheat your motor, your E800 will sound the alarm.
If you have a bad connection between ESC and motor, your E800 will refuse to start, If this happened during flight, it will sound the alarm and record this event in the onboard memory.
If you just flashed your ESC620S from 3510 to 2312 motor and hook it to a new motor, before the first start, the ESC will thoroughly diagnose your motor make sure this is a 2312 and it is healthy.
9. Redundant duplex communication
Just as lvale has guessed, E800 will feature a BUS port to communicate with FC. This enable the ESC and FC to communicate in both directions. There is a traditional PWM channel on E800 too, to make it compatible with nowaday flight controllers on the market. Supported with the right flight controller, these two communication channels will hot back up each other to guarantee reliability.
The duplex communication is a real game changer. Together with our real time diagnosis technologies build in the ESC, It enables the flight controller to have a full awareness of the situation in propulsion system. Now FC could know what the temperature every motors has, how fast every rotor is rotating and whether a turbo charge is neccessary and possible at the moment. If a motor fails, the FC will know it at the first second and switch on the preplanned strategy to cope with it.
The BUS channel will also make the FC to have a full use of the thi-color LEDs driven by the ESC. System status, alarms or simple decorative colors can be displayed by all the LEDs on the your DIY aircraft, just as the phanom.
10
Byebye BLDC
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