Low emission engine braking for vehicles

A vehicle comprising:

• an internal combustion engine (ICE) including an exhaust system having an electrically heated catalyst;
• at least one generator configured to convert rotation of the ICE into electrical energy;
• at least one motor configured to rotate or spin the ICE by consuming electrical energy;
• a rechargeable energy storage system electrically coupled to the at least one generator;
• and
• a controller including a memory and a processor, wherein the memory stores instructions for causing the processor to perform operations including:
• initiating a preheat in the electrically heated catalyst (EHC);
• and
• subsequent to initiating the preheat, allowing the internal combustion engine (ICE) to spin by one of:
• engaging the clutch, converting rotation of the ICE to electrical energy, and storing the electrical energy in a rechargeable energy storage system (RESS), and
• spinning the ICE using electrical energy from the RESS, generating regenerative braking energy, and storing the regenerative braking energy in the RESS.

A vehicle comprising:

• an internal combustion engine (ICE) including an exhaust system having an electrically heated catalyst;
• at least one generator configured to convert rotation of the ICE into electrical energy;
• at least one motor configured to spin the ICE by consuming electrical energy;
• a rechargeable energy storage system (RESS) electrically coupled to the at least one generator;
• and
• a controller including a memory and a processor, wherein the memory stores instructions for causing the processor to perform operations including:
• initiating a preheat in the electrically heated catalyst (EHC), wherein the pre-heat is initiated in response to detecting the vehicle beginning an extended grade descent and determining that a deceleration assist is required for a duration of the descent, and wherein determining that a deceleration assist is required comprises at least one of monitoring a pedal input, estimating a torque request, determining a deceleration rate of the vehicle, determining a time of the vehicle decelerating, determining a satellite positioning system of the vehicle, and an expected grade of a map location of the vehicle;
• monitoring a state of charge of the RESS, a grid temperature of the EHC, and a catalyst inlet temperature of a three-way catalyst and determining a first engine braking limit and a second engine braking limit based on the monitored state of charge of the RESS, the grid temperature of the EHC and the catalyst inlet temperature, wherein the first engine braking limit and the second engine braking limits are RESS state of charge values and wherein the second engine braking limit is higher than the first engine braking limit;
• comparing the state of charge of the RESS to the first engine braking limit and the second engine braking limit and enabling EHC preheat at the second engine braking limit and disabling EHC system at the first engine braking limit;
• comparing the catalyst inlet temperature and activating the EHC responsive to the catalyst inlet temperature being below a threshold, the activating including providing power from the RESS to the EHC;
• and
• subsequent to initiating the preheat, allowing the internal combustion engine (ICE) to spin by one of:
• engaging the clutch, converting rotation of the ICE to electrical energy, and storing the electrical energy in a rechargeable energy storage system (RESS), and
• spinning the ICE using electrical energy from the RESS, generating regenerative braking energy, and storing the regenerative braking energy in the RESS.