Battery usage?

[Redshift]

Redshift tell me what happens when you shift into reverse???? 

Since there is no reverses gear, the electric motor DOES reverse. It does not reverse when going down the highway. That would put way too much stress on the electric motors. Notice how Ford stresses in the owner's manual to be at a full stop when switching into reverses or you could damage the tranny.

[Redshift]

For those that don't understand how a Power Split transmission works go to this link and set the sliders in the animation as I describe below for examples of how positive, negative, EV, reverse, and stationary modes work.   The rpms shown are based on the Prius transmission.  The C-Max rpms will be different but the same principles apply.  Also, this diargam is for rpm only and not torque as the motors can supply positive or negative torque irrespective of rotational direction.

 

Stationary Mode:  vehicle is not moving.   1) set the traction motor slider (MG2) to zero mph. 2) move ICE slider up and down. 3) the generator rpm will be positive and the control algorithms will determine whether to charge the HVB by applying the appropriate three phase voltages and frequency to generator (MG1) so that current will flow from the generator to the inverter and then to the HVB.  The rotation of MG1 is deemed positive.

 

Reverse Mode:  vehicle is moving in reverse.  1) set the traction motor slider (MG2) to -10 mph.  2) move ICE slider to zero.  3) the generator rpm (MG1) will be positive.  The traction motor (MG2) will supply torque to the wheels so the vehicle moves in reverse (negative rpm).

 

EV Mode: ICE is off and vehicle is being propelled by the traction motor (MG2).   1) set ICE to zero rpm.  2) move MG2 slider up and down above zero rpm.  3) the generator rpm (MG1) will be negative.  For the C-Max, the gearing is such that rpm is almost a -1:1 ratio of MG1:MG2 rpm.  The control algorithms will use the energy from the HVB to operate MG2.  

 

Positive Split Mode:   ICE is on and vehicle is moving. HVB being charged.  1)  set ICE rpm slider and traction motor rpm slider (MG2) so that the generator rpm (MG1) is greater than zero.  This is positive split mode where the control algoritms determine how much ICE torque is applied to the generator to charge the HVB.

 

Negative Split Mode:  ICE is on, HVB SOC is high (control algorithms won't allow any more charge), and vehicle cruising at higher speed.  1)  Set MG2 rpm high (say above 65 mph) to simulate that EV mode would not likely be used.  2)  set ICE slider so that MG1 rpm is about zero.   3) now slide ICE rpm lower simulating constant torque but at reduced rpm (more efficient operating point on the BSFC map of ICE). MG1 rpm is negative (physical rotation has changed from positive split mode.  The control algorithms will operate MG1 as a motor applying torque to slow down ICE.  The traction motor rpm remains constant but may act as a generator to utilize the combined torque of ICE and MG1 or motor if additional torque is required in both cases to maintain speed.

 

As one can see from my graph in a previous post and the linked demo (despite what Redshift continues to say),  the algorithms will switch the physical direction of rotation of the generator extremely quickly via electronics and seamless to the driver for the benefit of operating most efficiently. 

 

https://www.thoughtco.com/how-electric-motors-and-generators-work-85463

 

Motor/Generators

Motor/generators are really one device that can run in two opposite modes. Contrary to what folks sometimes think, that does not mean that the two modes of the motor/generator run backwards from each other (that as a motor the device turns in one direction and as a generator, it turns the opposite direction). The shaft always spins the same way. The "change of direction" is in the flow of electricity. As a motor, it consumes electricity (flows in) to make mechanical power, and as a generator, it consumes mechanical power to produce electricity (flows out).

 

Edited October 3, 2018 by Redshift

[obob]

Since there is no reverses gear, the electric motor DOES reverse. It does not reverse when going down the highway. That would put way too much stress on the electric motors. Notice how Ford stresses in the owner's manual to be at a full stop when switching into reverses or you could damage the tranny.

 

As I recall someone posted they that accidentally put the transmission in reverse when it was moving forward and nothing happened.  The logic is smart enough not to actually do what the driver is trying to do.  

Edited October 3, 2018 by obob

[plus 3 golfer]

Please redshift, try to understand what happens.  No one said the traction motor reverses going down the highway. The generator motor MG1 will reverse going down the highway in negative split mode from positive split mode.  You clearly do not understand how a planetary gear set works even with my graph of actual data and the animation.  It seems you confuse torque flow from the motors with rpm.  The shafts do not have to always spin the same way.  The shafts can spin either way and act as a motor using electric power or as a generater making electric power no mater what direction the shafts spin.
 
obob is absolutely correct.  Nothing will happen as the algotithms monitor rpm of all rotating devices and will not allow conflicts to happen. Also, I wasted my time trying to validate your statement redshift: " Notice how Ford stresses in the owner's manual to be at a full stop when switching into reverses or you could damage the tranny."   I can't find where Ford says "or you could damage the tranny."  You made something up.  The likely reason you want to be at a full stop is safety oriented because the car will continue to move even though you shifted into R likely in the opposite direction one wants the car to move.
 
I'm done with trying to educate.  Believe what you want to redshift and quit adding misinformation to my posts to make it appear that I said it instead of you.

Edited October 3, 2018 by Plus 3 Golfer

[ptjones]

I have done this a number of times thinking I was in Drive shifting to Neutral to coast and instead being in Neutral and shifting into Reverse and nothing happens other than you can see who is behind you on the center screen. :)  There is no actual shifting involved with a CMAX CVT trans.

 

Paul

[stolenmoment]

+3, cut him some slack.  I have good mechanical intuition and it took me a long time to internalize how the planetary gearset works.

 

I've also seen different sources saying that the ICE is connected variously to the Sun gear and the Planetary gears.  I would think that connecting to the Sun gear would make the most sense, but I don't *know*.

[plus 3 golfer]

+3, cut him some slack.  I have good mechanical intuition and it took me a long time to internalize how the planetary gearset works.

 

I've also seen different sources saying that the ICE is connected variously to the Sun gear and the Planetary gears.  I would think that connecting to the Sun gear would make the most sense, but I don't *know*.

ICE is connected to the planet carrier (which hold the planet gears), generator (MG1) to the sun gear, and traction motor (MG2) to the ring gear. The planetary gears connect to the sun gear and ring gear.  

 

So with ICE off, the planet carrier does not spin and hence remains in a stationary position.  With ICE still off, the traction motor can propell the car ( EV mode) which will spin the ring gear and drive wheels.  The ring gear then spins the planet gears but the carrier remains stationary (ICE off).  The spinning planet gears then spin the sun gear (and generator)  So, ICE would have to spin if connected to the sun gear in EV mode.  ICE would have to spin both forward and backward.   The generator would be on planet carrier which could be allowed to spin with ICE stationary.  But, my guess is that the gearing would be significanly mismatched such that additional gears would be required with ICE on the sun gear and genetator on the planet carrier.  The current arrangement would likely result in a smaller transmission.

 

I have seen hybrid transmission designs that use clutches, a second planetary gear set, more gears that could allow ICE to be connected virtually anywhere.  But the C-Max  transmission is rather simplistic in design (although not intuitive) but requires software control rather than mechanical control to control power / torque / direction of travel. 

Edited October 5, 2018 by Plus 3 Golfer

[obob]

For those that don't understand how a Power Split transmission works go to this link and set the sliders in the animation as I describe below for examples of how positive, negative, EV, reverse, and stationary modes work.   The rpms shown are based on the Prius transmission.  The C-Max rpms will be different but the same principles apply.  Also, this diargam is for rpm only and not torque as the motors can supply positive or negative torque irrespective of rotational direction.

 

Stationary Mode:  vehicle is not moving.   1) set the traction motor slider (MG2) to zero mph. 2) move ICE slider up and down. 3) the generator rpm will be positive and the control algorithms will determine whether to charge the HVB by applying the appropriate three phase voltages and frequency to generator (MG1) so that current will flow from the generator to the inverter and then to the HVB.  The rotation of MG1 is deemed positive.

 

Reverse Mode:  vehicle is moving in reverse.  1) set the traction motor slider (MG2) to -10 mph.  2) move ICE slider to zero.  3) the generator rpm (MG1) will be positive.  The traction motor (MG2) will supply torque to the wheels so the vehicle moves in reverse (negative rpm).

 

EV Mode: ICE is off and vehicle is being propelled by the traction motor (MG2).   1) set ICE to zero rpm.  2) move MG2 slider up and down above zero rpm.  3) the generator rpm (MG1) will be negative.  For the C-Max, the gearing is such that rpm is almost a -1:1 ratio of MG1:MG2 rpm.  The control algorithms will use the energy from the HVB to operate MG2.  

 

Positive Split Mode:   ICE is on and vehicle is moving. HVB being charged.  1)  set ICE rpm slider and traction motor rpm slider (MG2) so that the generator rpm (MG1) is greater than zero.  This is positive split mode where the control algoritms determine how much ICE torque is applied to the generator to charge the HVB.

 

Negative Split Mode:  ICE is on, HVB SOC is high (control algorithms won't allow any more charge), and vehicle cruising at higher speed.  1)  Set MG2 rpm high (say above 65 mph) to simulate that EV mode would not likely be used.  2)  set ICE slider so that MG1 rpm is about zero.   3) now slide ICE rpm lower simulating constant torque but at reduced rpm (more efficient operating point on the BSFC map of ICE). MG1 rpm is negative (physical rotation has changed from positive split mode.  The control algorithms will operate MG1 as a motor applying torque to slow down ICE.  The traction motor rpm remains constant but may act as a generator to utilize the combined torque of ICE and MG1 or motor if additional torque is required in both cases to maintain speed.

 

As one can see from my graph in a previous post and the linked demo (despite what Redshift continues to say),  the algorithms will switch the physical direction of rotation of the generator extremely quickly via electronics and seamless to the driver for the benefit of operating most efficiently. 

 

I really appreciate this post and the included link.  It really takes the mystery out of what is going on.  Thanks.

[fbov]

...

 

https://www.thoughtco.com/how-electric-motors-and-generators-work-85463

 

Motor/Generators

Motor/generators are really one device that can run in two opposite modes. Contrary to what folks sometimes think, that does not mean that the two modes of the motor/generator run backwards from each other (that as a motor the device turns in one direction and as a generator, it turns the opposite direction). The shaft always spins the same way. The "change of direction" is in the flow of electricity. As a motor, it consumes electricity (flows in) to make mechanical power, and as a generator, it consumes mechanical power to produce electricity (flows out).

 

 

Folks get confused by polarity, and there are two polarities at work here, with all four combinations allowed.

 

The quote above refers to electric polarity: "The shaft always spins the same way." The only way to go from generating to consuming electricity is by changing the direction of current flow: "The 'change of direction' is in the flow of electricity."

 

The quote ignores rotational polarity. The electric polarity above only applies to one direction of rotation. Turn it the opposite way, and you get the opposite direction of current flow, but it remains a motor or a generator. The idea is as simple as hooking up a DC motor the opposite polarity to get it to reverse direction (although these aren't DC motors). 

 

Finally, Plus 3 has done a great job summarizing operational modes, made possible because only 2 of the 3 units are constrained, one by road speed, the other by fuel consumption. That's why the third unit requires a +/- 10,000 RPM operational range.

 

HAve fun,

Frank