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H-Bridge four quadrant Dc motor driver 2
- Thread starter mawad
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Skogsgurra
Electrical
Yes. But you need to make sure that the supply can take care of the regenerated power. A led battery usually can, a rectifier usually can't - unless designed to feed energy back to the mains. A braking resistor with a voltage relay or chopper is needed in most cases.
Gunnar Englund
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Half full - Half empty? I don't mind. It's what in it that counts.
Gunnar Englund
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Half full - Half empty? I don't mind. It's what in it that counts.
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If the term "four quadrant" is used correctly, then it can regenerate power, as Skogs says. By definition, two of the quadrants are motoring, and two are generating.
Skogs' warning about making sure you can handle the regenerated power is very important. The first place the power goes is to charge up the DC bus capacitors, increasing the bus voltage. If this has ANY possibility of increasing the voltage past safe limits, you must then be able to remove power from the capacitor bank by one of the methods he suggests.
Skogs' warning about making sure you can handle the regenerated power is very important. The first place the power goes is to charge up the DC bus capacitors, increasing the bus voltage. If this has ANY possibility of increasing the voltage past safe limits, you must then be able to remove power from the capacitor bank by one of the methods he suggests.
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- #4
Compositepro
Chemical
The little purple star (LPS) is for showing appreciation.
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- #6
@ Skogsgurra: could you please explain more what do you mean with a braking resistor with a voltage relay or chopper is needed in most cases?
Also, I would like to know in regenerative braking in hybrid and electrical vehicle. How they control the braking and charge the battery? I think that the vehicle kinetic will drive the motor in braking quadrant and generate back emf. This back emf will charge the battery, but how they control the braking level? and Is controlling the braking level will affect the regenerative energy?
Also, I would like to know in regenerative braking in hybrid and electrical vehicle. How they control the braking and charge the battery? I think that the vehicle kinetic will drive the motor in braking quadrant and generate back emf. This back emf will charge the battery, but how they control the braking level? and Is controlling the braking level will affect the regenerative energy?
A braking resistor is a LARGE resistor that is put across the capacitor bank to drain it. Of course you don't want this happening all the time so a control element is included to connect and disconnect it as needed. A "braking controller" of some sort watches the voltage as it builds across the capacitor bank. In normal operation the voltage on the bank is far below the point braking is needed. However, if the voltage reaches a high point, the controller connects the resistor up to rapidly drain charge off into heated air via the resistor. Typically this is done as PWM that gains in duty cycle the higher above the initial trigger voltage the capacitor voltage reaches.
In eVehicles, depending on the battery bank capacity some or all the charge from dynamic braking can be returned to the bank. However in non-eVehicles like Prius's since the bank is not as large as it would be if the car was a pure electric, the battery bank can sometimes not accept the full dynamic braking energy. I believe Prius's use a capacitor bank to take sudden large energy returns.
On a Prius they watch the 'gas pedal' and the brake pedal and control the dynamic braking in a way that won't surprise or confuse soccer-moms.
Keith Cress
kcress -
In eVehicles, depending on the battery bank capacity some or all the charge from dynamic braking can be returned to the bank. However in non-eVehicles like Prius's since the bank is not as large as it would be if the car was a pure electric, the battery bank can sometimes not accept the full dynamic braking energy. I believe Prius's use a capacitor bank to take sudden large energy returns.
On a Prius they watch the 'gas pedal' and the brake pedal and control the dynamic braking in a way that won't surprise or confuse soccer-moms.
Keith Cress
kcress -
In a hybrid vehicle (including the Prius) the DC link capacitors are only to handle the ripple current from the inverters and battery choppers. Because of the lifetime requirements, DC link capacitors are film caps in all hybrid vehicles. The total capacitance is very low.
In normal drive mode, if the battery can't take more charge the ECM starts using the mechanical brakes. There is no need to do anything fancy in that case, the brakes just revert to brakes like every other car has.
If the "brake" or "low" (depends on brand) mode is selected, then when the battery can't take charge, the engine will be used for compression braking. Again, this is just like any other vehicle - other than the electronic transmission being used to spin up the engine.
In normal drive mode, if the battery can't take more charge the ECM starts using the mechanical brakes. There is no need to do anything fancy in that case, the brakes just revert to brakes like every other car has.
If the "brake" or "low" (depends on brand) mode is selected, then when the battery can't take charge, the engine will be used for compression braking. Again, this is just like any other vehicle - other than the electronic transmission being used to spin up the engine.
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- #9
Many thanks itsmoked and MatthewDB
I have another question related to the attached photo. Does the attached 4-quadrant means that we can only regenerate energy in the regeneration space and if the torque and speed more than certain limits I couldn't regenerate energy and I need to apply more voltage than the back emf. If so, why they called this area the dynamic braking as I know the dynamic braking is done by using external resistor between the motor terminals, but in this case there is no resistor between the motor terminals why they called it dynamic braking.
I have another question related to the attached photo. Does the attached 4-quadrant means that we can only regenerate energy in the regeneration space and if the torque and speed more than certain limits I couldn't regenerate energy and I need to apply more voltage than the back emf. If so, why they called this area the dynamic braking as I know the dynamic braking is done by using external resistor between the motor terminals, but in this case there is no resistor between the motor terminals why they called it dynamic braking.
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