Well, we all thought about converting the existing or conventional vehicles to PHEVs. If we got our conventional cars, why not convert them into PHEVs?
Hybrid to PHEVs (Plug-in hybrid electric vehicles) can be done in two ways.
- The first method is by replacing the original battery pack (mainly a NiMH battery) with a larger battery such as Lithium-ion.
- The second method is by adding an extra battery pack to the vehicle system.
Mostly the Hybrid electric vehicle is available with a NiMH (Nickel-metal hydride) battery pack of 1.2 to 2.2 KWh. However, the converted Plug-in hybrid electric vehicle is usually available with a battery pack of 7-16 kWh.
A kind of alarming situation in the initial drive range for electric vehicles, either it will make it possible for the vehicle to drive at all electric-mode or a significant increase in the fuel consumption.
The approach of replacing the existing battery pack is done by manual removal of the original battery pack and installing a new battery pack. The battery energy is usually used either by manipulating or spoofing the replace battery energy.
The original battery ECU (electronic control unit) is replaced with a new battery ECU by duplicating all the battery information.
One way is, spoofing the real battery information to a value. It will make the vehicle controller think that sufficient energy is available to power the battery. Hence, the car will use more battery energy to drive the vehicle.
Another way is the battery data spoofed to use as a gateway. The gateway receives the real battery information to manipulate the battery data to the vehicle controller. The gateway can be installed as a part of the new battery ECU or standalone ECU.
The second method, adding an extra battery pack in the vehicle is used in A123 System’s Hymotion. The extra battery pack energy is released slowly in the original battery pack of the vehicle. The method eliminated the controlling of the new battery pack and hence no change in the original electrical and control systems.
However, an additional DC-DC converter will be needed in between the lithium-ion battery pack and the original NiMH battery pack. The converter will charge the original battery pack with the help of the energy from the added battery pack.
The SOC (State of Charging) of the NiMH battery pack is reset by the added battery ECU depending on the battery voltage. The energy that is charging the NiMH battery is used to detect the high (SOC) State of Charging.
In the case of the conventional gasoline vehicle, the existing front axle was kept as it is but the rear axle has been added up with an induction motor and an extra battery pack. The method was used in pickup trucks with abundant space. The Hybrid Electric Vehicle Technology Inc. and Raser Inc. both converted the gasoline pickup truck to a PHEV.
One important change was to modify the vehicle controller to take advantage of the battery energy.
Source:- Hybrid Electric Vehicles by Chris Mi, HEVT, Rasertech