REGENERATIVE BRAKE COOPERATIVE CONTROL
id042000001400
Purpose, Function
• The electronically controlled brake system obtains the total braking force by the regenerative braking force using an integrated starter generator, not just the braking force from general hydraulic brakes.
• For vehicles with the electronically controlled brake system, when the driver depresses the brake pedal, the integrated starter generator functions as a generator to generate electricity.
• If the regenerative brakes are not coordinated with the normal hydraulic brakes when the brake pedal is depressed, the braking force of the regenerative brakes would be added to the braking force generated by the amount of brake pedal depression by the driver, producing a greater than necessary amount of braking force which could cause loss of drivability and vehicle stability during deceleration.
• For this reason, the electronically controlled brake system calculates the braking force estimated by the driver based on the brake pedal depression amount, and it coordinates with the PCM to calculate the braking force of the hydraulic brakes according to the braking force of the regenerative brakes.
• As a result, the braking force of the hydraulic brakes is controlled so that the total braking force of the regenerative brakes and the hydraulic brakes matches the braking force estimated by the driver.
Construction
Operation
• Using the regenerative brake coordinated control, kinetic energy dissipated through the hydraulic brakes is kept low, allowing it to be recovered as efficient electrical energy. For maximum recovery of kinetic energy, the electronically controlled brake system performs coordinated control with the PCM to perform brake fluid pressure control according to the change in the regenerative braking force of the integrated starter generator.
• The operation load of the regenerative brakes and the hydraulic brakes occurring with each driving condition is as follows.
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― Required braking force is high:
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• The braking force by the hydraulic brakes is added to the braking force (regenerative brake) by the resistance of the integrated starter generator.
― Required braking force is low:
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• The braking force (regenerative brake) by the resistance of the integrated starter generator is used mostly in the brake operation range, and the hydraulic brakes operate just prior to the vehicle stopping.
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Note
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• In actual driving, braking force is added by engine braking according to the driving conditions.
