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Even if you start with a different motor that has them in parallel (a shunt or separately excited field - "SepEx" - type), you can't just connect them in series because in those motors the field winding is designed for much less current than the rotor winding.

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Remember the voltage and the current are dependent on each other

For any given rpm and current there is ONE voltage that will achieve that - the controller takes the battery voltage and reduces it to the correct voltage for the motor

Rough numbers - for illustration

Zero rpm --- 1000 amps motor ---- 15v motor ==== 150v battery and 100 amps battery

1000 rpm --- 1000 amps motor ---- 45 volts motor ==== 150v battery and 300 amps battery

2000 rpm --- 1000 amps motor ---- 80 volts motor ==== 150v battery and 533 amps battery

3000 rpm --- 1000 amps motor ---- 110 volts motor ==== 150v battery and 733 amps battery

4000 rpm --- 1000 amps motor ---- 140 volts motor ==== 150v battery and 933 amps battery

5000 rpm --- 800 amps motor ---- 150 volts motor ====150v battery and 800 amps battery

6000 rpm --- 600 amps motor ---- 150 volts motor ====150v battery and 600 amps battery

Well saidFor any given rpm and current there is ONE voltage that will achieve that - the controller takes the battery voltage and reduces it to the correct voltage for the motor

The required motor output torque determines the current required to produce the corresponding magnetic force. The motor speed and the current in the windings determines the voltage required to overcome back-EMF (the voltage induced in the motor's windings due to the changing magnetic field). The current in the windings and the resistance of windings determines the voltage required to overcome resistance.

In this example, the system of battery, controller, and motor is limited to 1000 amps by the controller, so at lower speeds that's the maximum current. At zero speed, 15 volts is required to overcome resistance.Remember the voltage and the current are dependent on each other

Rough numbers - for illustration

Zero rpm --- 1000 amps motor ---- 15v motor ==== 150v battery and 100 amps battery

1000 rpm --- 1000 amps motor ---- 45 volts motor ==== 150v battery and 300 amps battery

2000 rpm --- 1000 amps motor ---- 80 volts motor ==== 150v battery and 533 amps battery

3000 rpm --- 1000 amps motor ---- 110 volts motor ==== 150v battery and 733 amps battery

4000 rpm --- 1000 amps motor ---- 140 volts motor ==== 150v battery and 933 amps battery

5000 rpm --- 800 amps motor ---- 150 volts motor ====150v battery and 800 amps battery

6000 rpm --- 600 amps motor ---- 150 volts motor ====150v battery and 600 amps battery

As the speed increases, back-EMF increases so more voltage is required to sustain the same current.

After 4000 RPM all of the available voltage from the battery is needed to overcome back-EMF, so higher speed means less voltage remaining to overcome resistance, and so less current; with the same voltage and less current, power drops.

The controller "trades" voltage for current, and can't increase voltage, so it takes as much current from the battery as required to get enough power. Voltage from the battery multiplied by current from the battery is the power provided by the battery; voltage to the motor multiplied by current through the motor is the power supplied to the motor. The battery power will be more than the motor power, due to less than perfect controller efficiency.

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Hi Brian, I think I might not have explained myself very well. What I'm talking about here is that inside the warp9 the two pairs of brushes are connected to the external brush terminal posts in parallel (not in relation to the field posts).. the same for the two pairs of field poles they are in parallel with the field terminal posts. (Not in relation to the brushes terminal posts).

Even if you start with a different motor that has them in parallel (a shunt or separately excited field - "SepEx" - type), you can't just connect them in series because in those motors the field winding is designed for much less current than the rotor winding.

Then "externally" we run these two sets of connections in series. I do understand that the motor is called a series wound motor due to it being connected with its brushes and field terminals all in series with each other in the visible cable circuit to the controller.

So what I'm suggesting is:

The 4 field poles all connected inside the motor in series rather than parallel.

Then connected in series to the brushes and those 4 brushes also connected internally with each other in series rather than in parallel. And finally back to the controller circuit.

The idea behind this is that it would half the "current capacity" of the motor but at double the voltage without reducing the torque provided. Plus for temporary acceleration burst you could use 1000A at 288V and the motor sees only the same voltage at each brush contact as the normal configuration (at 144V) but you now have the equivalent of running a 144v controller with a 2,000A peak current for launching hard off the line.

Of course the idea is that this would also mean at regular cruise conditions your only running rather low battery current draw at the high system voltage. Potentially better overall efficiency etc etc. But with the ability to very very briefly push 288-300kW through a Single warP9 motor with a Soliton1.

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Hi Duncan, thanks for your great technical reply. Love the voltage/current breakdown. I poorly explained my theory im sorry.

Remember the voltage and the current are dependent on each other

For any given rpm and current there is ONE voltage that will achieve that - the controller takes the battery voltage and reduces it to the correct voltage for the motor

Rough numbers - for illustration

Zero rpm --- 1000 amps motor ---- 15v motor ==== 150v battery and 100 amps battery

1000 rpm --- 1000 amps motor ---- 45 volts motor ==== 150v battery and 300 amps battery

2000 rpm --- 1000 amps motor ---- 80 volts motor ==== 150v battery and 533 amps battery

3000 rpm --- 1000 amps motor ---- 110 volts motor ==== 150v battery and 733 amps battery

4000 rpm --- 1000 amps motor ---- 140 volts motor ==== 150v battery and 933 amps battery

5000 rpm --- 800 amps motor ---- 150 volts motor ====150v battery and 800 amps battery

6000 rpm --- 600 amps motor ---- 150 volts motor ====150v battery and 600 amps battery

What I'm talking about here is that inside the warp9 the two pairs of brushes are connected to the external brush terminal posts in parallel (not in relation to the field posts).. the same for the two pairs of field poles they are in parallel with the field terminal posts. (Not in relation to the brushes terminal posts).

Then "externally" we run these two sets of connections in series. I do understand that the motor is called a series wound motor due to it being connected with its brushes and field terminals all in series with each other in the visible cable circuit to the controller.

So what I'm suggesting is:

The 4 field poles all connected inside the motor in series rather than parallel.

Then connected in series to the brushes and those 4 brushes also connected internally with each other in series rather than in parallel. And finally back to the controller circuit.

The idea behind this is that it would half the "current capacity" of the motor but at double the voltage without reducing the torque provided. Plus for temporary acceleration burst you could use 1000A at 288V and the motor sees only the same voltage at each brush contact as the normal configuration (at 144V) but you now have the equivalent of running a 144v controller with a 2,000A peak current for launching hard off the line.

Of course the idea is that this would also mean at regular cruise conditions your only running rather low battery current draw at the high system voltage. Potentially better overall efficiency etc etc. But with the ability to very very briefly push 288-300kW through a Single warP9 motor with a Soliton1.

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7,791 Posts

Hi dkubus,Hi Duncan, thanks for your great technical reply. Love the voltage/current breakdown. I poorly explained my theory im sorry.

What I'm talking about here is that inside the warp9 the two pairs of brushes are connected to the external brush terminal posts in parallel (not in relation to the field posts).. the same for the two pairs of field poles they are in parallel with the field terminal posts. (Not in relation to the brushes terminal posts).

Then "externally" we run these two sets of connections in series. I do understand that the motor is called a series wound motor due to it being connected with its brushes and field terminals all in series with each other in the visible cable circuit to the controller.

So what I'm suggesting is:

The 4 field poles all connected inside the motor in series rather than parallel.

Then connected in series to the brushes and those 4 brushes also connected internally with each other in series rather than in parallel. And finally back to the controller circuit.

The idea behind this is that it would half the "current capacity" of the motor but at double the voltage without reducing the torque provided. Plus for temporary acceleration burst you could use 1000A at 288V and the motor sees only the same voltage at each brush contact as the normal configuration (at 144V) but you now have the equivalent of running a 144v controller with a 2,000A peak current for launching hard off the line.

Of course the idea is that this would also mean at regular cruise conditions your only running rather low battery current draw at the high system voltage. Potentially better overall efficiency etc etc. But with the ability to very very briefly push 288-300kW through a Single warP9 motor with a Soliton1.

You're missing the armature winding configuration. It is a 4 pole wave wound circuit meaning it has two circuits, in parallel. It's connected to a 49 segment comm. Each armature coil (there are 49 with one turn each) is connected to segments 180° apart. This coil is in the neutral zone so essentially has no generated voltage while undergoing commutation (touching brushes and having current reversed). So, what that boils down to is that the brushes at 180° are a common node. In fact, the motor can operate with just 2 of the 4 brush sets at 90° yielding the same performance only derated due to less brush area.

Regards,

major

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Seeing as how 2000A controllers are rare and expensive i was thinking this is therefore a better utilisation of the high voltage input abilities of the soliton1 and would maximise take off torque without needing to fit my second warp9 (saving 80+ kg). Weight is the enemy of hillclimb racing.

Cheers for putting up with me.

Kind regards

Mike.

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7,791 Posts

Hi Mike,

Seeing as how 2000A controllers are rare and expensive i was thinking this is therefore a better utilisation of the high voltage input abilities of the soliton1 and would maximise take off torque without needing to fit my second warp9 (saving 80+ kg). Weight is the enemy of hillclimb racing.

Cheers for putting up with me.

Kind regards

Mike.

Sorry, cannot follow your logic. But your conclusion is wrong. You will not better performance by messing with the brushes. Google and study "dc motor wave wound armature", without quotes. Here's a linky.

Wave Winding | Electrical Study App by SARU TECH

Regards,

major

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44 Posts

Thanks for setting me straight on this Major, sincerely appreciate it. This is what I've been trying to research for a while now but didn't know the terminology to search for. As always reading your descriptions and following the link you gave has clearly identified my mistake with my optimistic brain fart. Cheers mate.Hi Mike,

Sorry, cannot follow your logic. But your conclusion is wrong. You will not better performance by messing with the brushes. Google and study "dc motor wave wound armature", without quotes. Here's a linky.

Wave Winding | Electrical Study App by SARU TECH

Regards,

major

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