Hi guys,
I need some help and advice from people with a better grasp on electronics than I have. I'm trying to use a 3-phase brushless motor (RC motor) as a generator for a series-hybrid vehicle and don't know what kind of electronics are best suited for my purpose. I want to use the RC motor to keep a battery fully charged.
Some things I know
I have 9 kW mechanical power readily available at 6000-8000 rpm
I have a big RC motor, or a couple smaller ones on a single shaft, that can run continuously at that power. The Kv of the motor can be picked so that the voltage would be 65-70 volts if it runs at 8000 rpm. I.e. suitable for charging my battery.
I have a 60V (14s) LiPo battery that I can charge at 2C, maybe 5C burst.
I have a load that's highly variable and might burst to 20+ kW.
The battery's there as a buffer. The genset can't output 20 kW but it CAN supply more than the average power consumption. A reasonably efficient system should be able to output at least 7 kW (assuming 2kW losses from the 9kW mechanical power I started with).
What electronics can I use to take the electrical output from the RC motor to keep the battery charged?
I don't want to overcharge the LiPo battery. I'm pretty sure I can't go above the 4.2 v/cell limit during charging. I can monitor the charge rate and the draw rate and keep track of how much energy is in the battery-- so I'll know if it needs genset power or not. I think this is necesssary because simply looking at the battery voltage is an unreliable indicator of state of charge. Under load, the voltage will sag a bit. Doesn't mean the battery's empty. There won't be opportunities to look at the 'resting voltage' of the battery.
So, can I simply stick a 3-phase rectifier on the RC motor, and PWM the connection with some mosfets? Is this an 'active rectifier'?
It might be functional/effective to use an ebike motor controller in regen mode, but I don't think it's ideal.
Does anyone know the best way to approach this?
I need some help and advice from people with a better grasp on electronics than I have. I'm trying to use a 3-phase brushless motor (RC motor) as a generator for a series-hybrid vehicle and don't know what kind of electronics are best suited for my purpose. I want to use the RC motor to keep a battery fully charged.
Some things I know
I have 9 kW mechanical power readily available at 6000-8000 rpm
I have a big RC motor, or a couple smaller ones on a single shaft, that can run continuously at that power. The Kv of the motor can be picked so that the voltage would be 65-70 volts if it runs at 8000 rpm. I.e. suitable for charging my battery.
I have a 60V (14s) LiPo battery that I can charge at 2C, maybe 5C burst.
I have a load that's highly variable and might burst to 20+ kW.
The battery's there as a buffer. The genset can't output 20 kW but it CAN supply more than the average power consumption. A reasonably efficient system should be able to output at least 7 kW (assuming 2kW losses from the 9kW mechanical power I started with).
What electronics can I use to take the electrical output from the RC motor to keep the battery charged?
I don't want to overcharge the LiPo battery. I'm pretty sure I can't go above the 4.2 v/cell limit during charging. I can monitor the charge rate and the draw rate and keep track of how much energy is in the battery-- so I'll know if it needs genset power or not. I think this is necesssary because simply looking at the battery voltage is an unreliable indicator of state of charge. Under load, the voltage will sag a bit. Doesn't mean the battery's empty. There won't be opportunities to look at the 'resting voltage' of the battery.
So, can I simply stick a 3-phase rectifier on the RC motor, and PWM the connection with some mosfets? Is this an 'active rectifier'?
It might be functional/effective to use an ebike motor controller in regen mode, but I don't think it's ideal.
Does anyone know the best way to approach this?
