Controller of hybrid system

A controller of a hybrid system including an internal combustion engine and a motor generator connected to each other via a belt, the controller comprising:

• processing circuitry configured to execute:
• a power generation process that applies a load to the internal combustion engine by controlling the motor generator to generate power in response to a first execution condition of an idling stop being satisfied;
• a slip rate calculation process that calculates a slip rate of the belt based on a rotational speed of the internal combustion engine and a rotational speed of the motor generator while the power generation process is being executed;
• a repeat process that repeats, in response to the slip rate being equal to or more than a threshold, the power generation process and the slip rate calculation process after waiting until a predetermined period has elapsed;
• a determination process that determines, in response to the slip rate being less than the threshold, whether or not a second execution condition of the idling stop is satisfied without waiting for the predetermined period to elapse;
• and
• an idling stop process that stops an operation of the internal combustion engine, in response to the determination process determining that the second execution condition of the idling stop is satisfied.