Toyota has some six principal patents on the THS. Highlights from these include:

According to US5907191, speed control of the generator, motor, and engine is executed in parallel, and torque control is executed every 4 ms.

According to US5914575, the generator and motor are controlled so as to maximise the energy regenerated on overrun or when braking, and this is possible even while the engine is operated at an efficient condition.

According to US6005297, reverse can be provided without additional components, and this is possible even while charging the battery from the engine.

According to US6067801, the generator, motor, and engine may be controlled so as to avoid shock (including rattling of gears) when the engine goes from drive to overrun.

According to US6131680, the generator, motor, and engine, together with the power-split device, allows the engine to be run at conditions favourable for emissions and efficiency, and allows the output of the motor to be combined with that of the engine. In all they support: motor-driving mode (for launch and the lowest speeds), charge-discharge mode (for low speeds), power-assist mode (for acceleration and hill-climbing), ordinary driving mode (for high speeds), and lock-up mode (for regenerative braking). In effect, this is the master patent for the Toyota Hybrid System.

According to US6161640, the engine is not stopped unless (for example): the engine and catalyst have warmed up, and unless the vehicle has stopped for 4 s (to avoid too-frequent stops and starts).