Controller for hybrid electric vehicle and method for controlling hybrid electric vehicle

A controller for a hybrid electric vehicle, the hybrid electric vehicle including a drive system including an engine, a first rotary electric machine, and a second rotary electric machine, the engine including a filter configured to collect particulate matter from an exhaust gas, the first rotary electric machine being configured to generate rotational force applied to the engine in accordance with supply of electric power from a battery, and the second rotary electric machine being configured to receive rotational force transmitted from a wheel and generate electric power, the controller comprising:

• processing circuitry configured to execute;
• a fuel cut-off process that performs a fuel cut-off of the engine to generate engine braking during deceleration of the hybrid electric vehicle,
• a drive force switching process that reduces a braking torque generated by the drive system during deceleration of the hybrid electric vehicle so that when execution of the fuel cut-off process is prohibited, the braking torque is less than when execution of the fuel cut-off process is permitted,
• a motoring process that rotationally drives the engine using the first rotary electric machine to burn and remove the particulate matter collected on the filter during deceleration of the hybrid electric vehicle, and
• a setting process that sets a vehicle speed at which execution of the motoring process is permitted to be higher when execution of the fuel cut-off process is prohibited than when execution of the fuel cut-off process is permitted;
• and
• a storage device storing:
• a first relationship between a state of charge of the battery and a motoring permission vehicle speed in a state that the braking torque being reduced by the drive force switching process;
• and
• a second relationship between the state of charge of the battery and the motoring permission vehicle speed in a state that the braking torque being not reduced by the drive force switching process,
• wherein
• for a same value of the state of charge of the battery, the motoring permission vehicle speed is set to a higher motoring permission vehicle speed in the first relationship than in the second relationship, and
• the processing circuitry is configured to execute:
• in response to determining the braking torque being reduced by the drive force switching process, calculate a motoring permission vehicle speed based on the first relationship, and
• in response to determining the braking torque being not reduced by the drive force switching process, calculate the motoring permission vehicle speed based on the second relationship.