Description and Operation

Description

Regenerative Brake System

During deceleration or braking of an electric vehicle or hybrid electric vehicle, the drive motor operates as an AC generator and charges the battery by converting the vehicle's kinetic energy generated during braking into electrical energy. The amount of regenerative braking depends on vehicle speed, battery charge, etc. Significant improvement in fuel economy is achieved in city driving with repeated acceleration and braking.

Regenerative Brake Control (RBC) System

Braking force distribution is achieved by controlling hydraulic braking, and the total braking force (hydraulic + regenerative braking) required by the driver is generated as output. In the event of a regenerative brake failure, the total braking force required by the driver is provided by the hydraulic brake system.

The AHB system consists of the Pressure Supply Unit (PSU) and the Integrated Brake Actuation Unit (IBAU). First, the PSU generates the hydraulic pressure required for braking. Similar to the booster effect when the driver depresses the brake pedal in a system equipped with a vacuum booster, the hydraulic pressure stored in the accumulator is supplied to provide pressure throughout the brake line. Second, the IBAU delivers the pressure generated by the PSU to the caliper at each wheel. It is connected to the brake pedal to determine the braking force required by the driver and to generate brake pedal feel. The IBAU performs ABS, TCS and ESC functions as in conventional vehicles.

AHB System Operating Principles

1. Initial Status

High pressure (180 bar) between the PSU and IBAU is generated continuously. Therefore, before removing the PSU or IBAU, the high pressure between them must be relieved for safety by performing the "High Pressure Release Mode" of the GDS connected to the GEM.

2. Brake Operation

Apply mode: during normal braking, the IN valve is energized and opens; then the high pressure generated by the PSU is supplied to the caliper at each wheel through the IBAU, and braking is applied.

The brake force level is determined by the pedal simulator, based on the brake pedal travel sensor measurement. Release mode: During brake release, the OUT valve opens and the IN valve closes; then, high-pressure brake fluid returns to the PSU. At this time, the CUT valve is ON, which prevents brake fluid from flowing back to the IBAU.

2. Brake Malfunction

If the PSU or IBAU is faulty, the IN valve and OUT valve do not operate. The valves remain closed, and the CUT valve is off. Therefore, braking force is generated only by the driver manually depressing the brake pedal.

Active Hydraulic Booster (AHB) Circuit Diagram (1)

Active Hydraulic Booster Circuit Diagram (2)

Active Hydraulic Booster (AHB) Circuit Diagram (3)

Active Hydraulic Booster (AHB) Circuit Diagram (4)

IBAU Connector Input/Output

		Description			Description
1.	R	E/R Fuse and Relay Box (Multi-Fuse — AHB 1)	24.	P	Electric Parking Brake Switch (Auto Hold Switch)
2.	R	Power Supply Motor (+)	25.	-	-
3.	-	-	26.	-	-
4.	B/O	Power Supply Motor (Ground)	27.	G	Rear Left Wheel Sensor (SIG)
5.	P/B	E/R Fuse and Relay Box (Fuse — AHB 3)	28.	B	Front Left Wheel Sensor (SIG)
6.	R	Brake Pedal Module (PDT PWR)	29.	L	Driver Door Switch
7.	R	Brake Pedal Module (PDF PWR)	30.	W	E/R Fuse and Relay Box (Multi-Fuse — AHB 2)
8.	L	Electronic Stop Lamp Module	31.	B	Brake Pedal Module (PDF GND)
9.	B	Yaw Rate Sensor (GND)	32.	-	-
10.	B	Brake Pedal Module (PDT GND)	33.	or	Rear Left Wheel Sensor (VCC)
11.	B/O	Power Supply Motor (Ground)	34.	W	Rear Right Wheel Sensor (VCC)
12.	-	-	35.	-	-
13.	B	Power Supply Motor (-)	36.	G	Electronic Stop Lamp Module
14.	B	Ground (GE06)	37.	W	Electronic Stop Lamp Module
15.	R	Yaw Rate Sensor (PWR)	38.	W	Yaw Rate Sensor (CAN — High)
16.	D	Emergency Stop Switch (ESC OFF Switch)	39.	D	Yaw Rate Sensor (CAN — Low)
17.	D	Front Left Wheel Sensor (VCC)	40.	W	Vehicle Speed: Smart Key Control Module, PCM
18.	R	Front Right Wheel Sensor (VCC)	41.	-	-
19.	W	C-CAN (High)	42.	L	Front Right Wheel Sensor (SIG)
20.	Br	C-CAN (Low)	43.	O/B	Rear Right Wheel Sensor (SIG)
21.	-	-	44.	L/O	Stop Lamp Switch
22.	W	Brake Pedal Module (PDT SIG)	45.	-	-
23.	Gr	Brake Pedal Module (PDF SIG)	46.	B	Ground (GE06)

Operation and Leak Check

Check all of the following items:

Component	Procedure
Integrated Brake Actuator Unit (IBAU) (A) and Power Supply Unit (PSU) (B)	Check brake operation by applying the brakes during a test drive. If the brakes do not operate properly, inspect the IBAU and power supply unit. Replace the IBAU and PSU assembly if it does not operate properly or if there are signs of leakage.
Inspect Piston Seal and Boot (B)	Check braking by applying the brakes. Look for damage or signs of brake fluid leakage. Replace the IBAU assembly if the pedal does not operate properly or if there is damage or signs of brake fluid leakage.
Brake Hoses (C)	Check for damage or signs of fluid leakage. Replace the brake hose with a new one if it is damaged or leaking.
Caliper Piston Seal and Piston Boot (D)	Check brake operation by depressing the brake pedal. Check for damage or signs of fluid leakage. If the pedal does not operate properly, the brakes do not brake properly, or there is damage or signs of fluid leakage, disassemble and inspect the brake caliper. Replace the boots and seals with new ones whenever the brake caliper is disassembled.