One article to thoroughly understand the work principle of the four-in-one integrated controller

Author:F-Diesel Date:August 25, 2025 2:35 AM Tag:[ high-voltage , oil pump controller , air pump controller , DC-DC converter in EVs ]

This knowledge base introduces or describes the This article explains the working principle of the 4-in-1 integrated controller in new energy vehicles, which combines a high-voltage power distribution unit (PDU), oil pump controller, air pump controller, and DC-DC converter. It details the power distribution, pre-charging circuits, contactor control, protection functions, and how each subsystem supports steering, braking, air conditioning, and low-voltage power supply.

1、Working Principle of the 4-in-1 Integrated Controller

1.1 PDU

1.2 oil pump controller

1.3 air pump controller

1.4 DC-DC

1、Working Principle of the 4-in-1 Integrated Controller:

The 4-in-1 controller consists of a high-voltage power distribution unit (PDU), an oil pump controller, an air pump controller, and a DC-DC converter, hence its name.

1.1 PDU：

The PDU is powered by a power battery and distributes power to the refrigeration compressor (air conditioning), PTC (electric heating), the internal three-in-one controller (oil pump controller, air pump controller, DC-DC converter), and the MCU (motor controller). The refrigeration compressor and MCU have large internal capacitors, so the 4-in-1 PDU is equipped with pre-charging circuits for these two units.

The PDU distributes power via contactor activation/deactivation.The activation/deactivation of the contactors is initiated by the VCU (vehicle control unit), which is interpreted and executed by the high-voltage control board (HCP). The HCP closes/opens the contactors upon receiving the VCU's signal. Only two pre-charging contactors are controlled by the HCP: the main motor pre-charging contactor and the air conditioning pre-charging contactor. Upon receiving a close command from the main motor contactor or the air conditioning contactor, the HCP will first close the corresponding pre-charging contactor and then close the corresponding contactor after pre-charging is complete. Each electrical appliance within the four-in-one system is equipped with a positive fuse at the front end. Capacities are as follows: 800A for the main motor, 32A for the air conditioner, 32A for the PTC, 32A for the oil pump controller, 32A for the air pump controller, and 16A for the DC-DC converter.

1.2 oil pump controller：

The oil pump controller drives the oil pump motor, which in turn drives the hydraulic power steering pump, providing steering assistance for the vehicle. The oil pump controller is a power conversion device that converts the DC power from the power battery into three-phase AC power. With a rated capacity of 7.5kVA, it features a range of protections, including input over/undervoltage protection, output overcurrent, and output overload.

1.3 air pump controller：

The air pump controller drives the air pump motor, which drives the air compressor, providing pressure for the air brake. It shares the same hardware as the oil pump controller.

1.4 DC-DC：