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

A controller for a hybrid electric vehicle including an engine, a motor generator, a belt connecting the engine, an air-conditioning compressor, and the motor generator, a first battery configured to supply the motor generator with power, a starter configured to start the engine by driving a transmission connected to the engine, and a second battery configured to supply the starter with power, a voltage of the first battery being higher than a voltage of the second battery, the controller comprising:

• processing circuitry configured to execute an engine starting process when an execution condition for starting the engine is satisfied, wherein:
• the engine starting process includes
• determining whether the engine is initially started,
• when it determined that the engine is initially started, setting a counted occurrence to zero,
• executing a first starting process that drives the motor generator by supplying the motor generator with power from the first battery to crank the engine,
• determining whether the first starting process has failed to start the engine when a shifting condition is satisfied,
• when it is determined that the first starting process has not failed to start the engine, setting the counted occurrence to zero,
• when it is determined that the first starting process has failed to start the engine,
• incrementing the counted occurrence by one,
• executing a second starting process that includes reducing the supply of power from the first battery to the motor generator and then driving the motor generator by increasing the supply of power from the first battery to the motor generator to crank the engine,
• determining whether the second starting process has failed to start the engine,
• when it is determined that the second starting process has failed to start the engine, starting the engine with the starter by supplying the starter with power from the second battery to drive the transmission to start the engine, and prohibiting operation of an idle reduction system of the engine, and
• when it is determined that the second starting process has not failed to start the engine
• comparing the counted occurrence to a determination threshold value, and
• prohibiting the operation of the idle reduction system of the engine when the counted occurrence is greater than or equal to the determination threshold value.