Learn more about the various technologies used in Toyota's fuel cell vehicles
This device generates electricity through a chemical reaction between hydrogen and oxygen. Hydrogen and ambient air are respectively supplied to the anode (negative) and the cathode (positive) of the fuel cell to generate electricity.
A fuel cell unit consists of a stack of cells called an MEA (Membrane Electrode Assembly) sandwiched between separators. The MEA is a polymer electrolyte membrane with catalyst layers applied. Since one cell can only yield less than 1 volt, several hundred cells are connected in series to increase the voltage. This combined body of cells is called a fuel cell stack (FC stack). This FC stack is commonly referred to as a fuel cell unit.
Fuel cell structure
High energy efficiency is one big advantage of using hydrogen in a fuel cell. Since it is possible to produce electricity directly from hydrogen without combustion, theoretically 83% of the energy held in a hydrogen molecule can be converted into electrical energy, which is currently more than double the energy efficiency of a gasoline powered engine.
Mechanism of electricity generation from hydrogen and oxygen in a fuel cell
1. Hydrogen is supplied to the anode side.
2. Hydrogen molecules activated by the anode catalyst release electrons.
3. The electrons released from hydrogen travel from the anode to the cathode, creating an electrical current.
4. Hydrogen molecules that released electrons become hydrogen ions and move through the polymer electrolyte membrane to the cathode side.
5. Hydrogen ions bond with airborne oxygen and electrons on the cathode catalyst to form water.
A secondary battery is capable of storing and discharging electrical energy. Energy regenerated by the motor under deceleration is stored in the secondary battery
The TOYOTA FCHV-adv is equipped with a nickel-metal hydride battery with a maximum power output of 21 kW. Regenerated energy under deceleration is stored in this secondary battery and supplements power from the fuel cell by providing auxiliary power under acceleration.
An AC synchronous motor developed by Toyota is used in the TOYOTA FCHV-adv. This motor functions as a generator under deceleration to regenerate energy.
Max. power output: 90 kW (122 PS)
Max. torque: 260 N·m (26.5 kgf·m)
The power control unit in the TOYOTA FCHV-adv consists of an inverter that converts DC into AC to power the motor and a DC/DC converter that draws current from and recharges the secondary battery, among other systems. It exercises precision control over fuel cell power output and secondary battery discharge and recharge under all driving conditions.
A 70 MPa high-pressure hydrogen tank developed by Toyota is installed in the TOYOTA FCHV-adv. The latest 70 MPa tank features a polyamide resin liner in the inner most layer of the tank due to its high strength and excellent hydrogen permeation prevention performance. Increased tank capacity and reduced weight have been achieved by using optimum materials, improving design and production methods, and minimizing wall thickness by optimizing the winding angle, tension and volume of the carbon fiber. This has contributed to significant improvement in cruising range.