RU2817426C1 - Precharge system for electric highly automated vehicle of category n3 - Google Patents

Abstract

FIELD: vehicles; electricity.

SUBSTANCE: invention relates to a precharge system for an electric highly automated vehicle of category N3. System consists of two parts. First part is located in housings of at least two parallel connected traction accumulator batteries (TAB). Second part is located in the housing of the power distribution module. First part consists of negative/positive line contactor, precharge resistor, main contactor, current sensor and BMS board, by means of which current and voltage values of all accumulator arrays are monitored. Second part is formed by the main essential contactor, the main pre-charge contactor, the main pre-charge resistor and the main BMS board, by means of which the value of current and voltage is monitored and at least two accumulator batteries are balanced in the presence of different voltage levels on each of them. Parts of the system are connected via positive and negative main buses.

EFFECT: reduced effect of welding contactors of high voltage at TAB unbalance.

1 cl, 1 dwg

Description

Field of technology to which the invention relates

The invention relates to the field of electrical engineering, namely to a pre-charge control system for the safe switching on of high voltage supplied from traction batteries to the on-board network for the needs of an electric highly automated vehicle of category N3.

State of the art

A large number of types of energy converters for different applications are known from the prior art.

A known circuit for controlling the pre-charge of an electric vehicle (CN 208714975 U, B60L 53/00, publ. 04/09/2019), which includes a logical control unit, a voltage recording unit, a main relay, a pre-charge relay, a pre-charge resistor, BUS bus capacitors and a battery , wherein the precharge resistor is connected in parallel with the main relay, and the main relay provides connection between the BUS bus capacitor and the battery.

The disadvantage of this system is that the precharge system circuit involves controlling the charge of an electric vehicle, which contains one battery; in addition, there is no system for balancing battery modules during the charging and discharging process.

A precharge controller is known (US 2020195016 A1, H02J 7/00, publ. 06/18/2020), which includes a main contactor, a capacitor, a precharge contactor, a current sensor and a control unit. When power is supplied from the traction battery to the current consumers, the control unit begins pre-charging by closing the pre-charging contactor when the detected current is equal to the set value or below, determines the end of pre-charging when the detected current is equal to or greater than the first threshold value and drops to the second threshold value value or lower and closes the main contactor.

The disadvantage of this controller is that the device does not provide monitoring and control of the battery status.

A pre-charge resistor protection device is known (US 2020144832 A1, H02H 1/00, publ. 05/07/2020), adopted as a prototype, including one or more sensor units configured to measure battery voltage applied to both ends of a battery element included in the unit battery, and the precharge current flowing in the precharge resistor. In addition, the device design assumes the presence of a processor operatively connected to the sensor unit.

The disadvantages of this device are the inability to balance the modules in the battery during discharge and charging.

Disclosure of the invention

The problem that the proposed technical solution solves is the creation of a precharging system to ensure the safe switching on of high voltage, by limiting a sharp current surge, as well as the safe switching on of two or more parallel-connected accumulator arrays (batteries) when each of them has a different voltage level.

The technical result of the claimed invention is the balancing of two or more parallel-connected traction batteries (TAB), which, in turn, ensures regulation of the high voltage value supplied from two or more TAB for the needs of an electric highly automated vehicle (VATS), and also increases the service life battery component services.

The specified technical result is achieved using the claimed precharge system for an electric highly automated vehicle of category N3, one of the parts of which is located in the housings of at least two parallel-connected traction batteries and consists of a negative/positive line contactor, a precharge resistor, a main contactor, a current sensor and BMS boards, through which the current and voltage values of all battery arrays are monitored, while parts of the system are connected through the main buses (plus and minus), and the second part is located in the housing of the power distribution module, and is formed by the main main contactor, the main precharge contactor, the main precharge resistor and the main BMS board, with the help of which the current and voltage are monitored, and at least two batteries are balanced with a different voltage level on each of them, which ensures the safe inclusion of high voltage, by limiting the peak current, for further its supply for the needs of the vehicle.

The declared technical solution is implemented by dividing the pre-charge system into two parts, one of which is located in the TAB housing and monitors the parameters (voltage, current) of each battery cell using the TAB BMS board, and the other part is located in the power distribution housing and performs the functions , through the main BMS board, both monitoring the voltage and current received from two or more parallel connected batteries, and balancing these batteries, while controlling the peak voltage values that are then supplied to the needs of the electric highly automated vehicle. This approach allows you to increase the service life of system components and avoid the effect of welding of high voltage contactors when the TAB is unbalanced.

Brief description of drawings

In FIG. Figure 1 shows a diagram of the structure of the precharge system, where:

1. TAB1 housing

2. TAB2 housing

3. Precharge contactor

4. Precharge resistor

5. Main contactor

6. Battery BMS

7. Battery module

8. Negative/positive line contactor

9. Current sensor

10. Cell voltage control board

11. Power distribution module housing

12. Main board BMS

13. Main main contactor

14. Main precharge contactor

15. Main precharge resistor

16. Main bus positive

17. Main bus negative

The precharge system consists of two parts: the first part is located in the TAB1 (1) and TAB2 (2) housings, which are connected to the second part - the power distribution module housing (11). Each TAB housing contains series-connected battery modules (7), each containing 12 lithium iron phosphate-based battery cells, also connected in series. To implement the precharging system in the TAB, a precharge contactor (3), a precharge resistor (4), a main contactor (5), a minus/plus line contactor (8) and a current sensor (9) are connected to the battery modules (7). Each battery module (7) is equipped with a cell voltage control board (10), which allows for more accurate control of the voltage value on each cell. Monitoring the state of each individual TAB is carried out using a BMS board in the battery (6).

In the housing of the power distribution module (11), the voltage and current received from TAB1 (1) and TAB2 (2) are monitored and then supplied to the needs of an electric highly automated vehicle of category N3. To do this, each of the TABs is connected to the power distribution module through electrical connectors, which are connected to the main main contactor (13), the main precharge contactor (14), the main precharge resistor (15) and two main buses: positive (16) and negative (17 ) lines. Balancing and monitoring the state of two parallel-connected arrays of battery modules located in the TAB1 (1) and TAB2 (2) housings in the power distribution module is carried out using the main BMS board (12), which provides control of the logical process of operation of the precharge system as a whole.

Carrying out the invention

When creating a VATS of category N3 with an electric drive, a rechargeable battery is used as an energy source. To achieve the required voltage value (increase in volumetric energy), a circuit was created from two parallel-connected arrays of battery cells as part of a TAB. When a battery supplies voltage directly to an electric motor, a large inrush current is generated, which damages the electrical components in the circuit. In addition, when implementing a system of two or more TABs, there is a need to balance them in the presence of different voltage levels on each of them. Thus, the design of the precharge system involves division into two components. The first part of the system is located in the traction battery housing and controls the battery modules in the TAB (voltage and current values are regulated).

In all operating modes of the system, the batteries must be continuously polled for errors and the status of the insulation monitoring board. In the event of an EMERGENCY signal (critical battery error or insulation breakdown), the system must immediately send a signal to the upper-level controller (HLC), wait for the current to drop on the battery buses, then open all contactors. If the current decline does not occur within 5 seconds, open the circuit without waiting for the current to decline.

Monitoring of the state of battery modules and balancing of cells in the TAB is carried out constantly using the BMS board with data transmission to the KVU, while monitoring of exceeding threshold voltages and imbalance is carried out on an ongoing basis. The BMS board checks the health of the batteries, and, in the event of a battery failure, transmits an error code via the CAN bus or sets a flag for the corresponding failure. The amount of battery discharge current is set by the user.

When the battery is turned on, the following sequence of actions occurs: the BMS boards (located in the batteries and in the power distribution module) are supplied with a 24V supply voltage. Next, the battery status is polled and data on the status is transferred to the HCU. If there are no critical errors, the main BMS board gives a command to the BMS boards located in the TAB to turn on. If there is a breakdown, the contactor is switched off and a critical error is generated.

If there is no error, the BMS boards in TAB1 and TAB2 are polled about the voltage on the batteries. If the voltage difference between the batteries is more than 5 V, then during battery monitoring the system determines the TAB with the lowest and highest voltage value, after which the main BMS board decides to turn on the charge contactor on the TAB with the lowest voltage, as a result of which current flows through the main precharge resistor and goes to the needs of an electric vehicle.

If the difference between the batteries is less than 5 V, then the main BMS board sends a command to the BMS boards in TAB1 and TAB2 to turn on the battery precharge contactors. Balancing the voltage and current levels on the two batteries is controlled via the main BMS board. Upon achieving battery balancing or after the currents drop below a certain level, the battery load contactors are turned on and the battery precharge contactors are turned off. If at this stage the battery BMS board is polled and there are no critical errors, then the main BMS board sends (via CAN) a readiness flag for further operation. If there are no critical errors, the main BMS board turns on the main precharge contactor. When the load capacitance voltage reaches a certain value, the upper level controller sets the main main contactor enable bit, the main BMS board closes the main contactor.

Accordingly, the main operating algorithm includes the following sequence of actions:

• 24V voltage is supplied to power the BMS boards in the power distribution module and in TAB1, TAB2.

• The main BMS board determines whether there is a difference in battery voltage (may change if emergency movement was performed).

• The main board selects the battery with the lowest charge and turns on the battery load contactor in it.

• The KVU transmits commands for precharging and turning on the main power contactor.

• If there are no critical errors, the CCU issues a charge enable flag, which causes the main board to request charging current to the on-board charger.

• Charging continues until the voltages between the batteries are equalized. In this case, the voltage imbalance flag between the batteries disappears.

• When the voltage imbalance flag is removed, the KVU removes the charging permission flag and the contactor switching signals.

• The main BMS board balances both batteries and then the charging or discharging (operation) procedure is carried out normally.

Thus, the described system is used to ensure the safe switching on of high voltage for the needs of an electric highly automated vehicle of category N3, and also monitors the voltage and current of battery modules and balances parallel-connected traction batteries.

The claimed technical solution meets the requirement of industrial applicability and can be implemented on any ground-based electric highly automated vehicles.

Claims (1)

A precharge system for an electric highly automated vehicle of category N3, one of the parts of which is located in the housings of at least two parallel-connected traction batteries and consists of a negative/positive line contactor, a precharge resistor, a main contactor, a current sensor and a BMS board, through which control is carried out current and voltage values of all battery arrays, while parts of the system are connected through the main buses (positive and negative), and the second part is located in the housing of the power distribution module and is formed by the main main contactor, the main precharge contactor, the main precharge resistor and the main BMS board, with with the help of which the magnitude of current and voltage is monitored and at least two batteries are balanced in the presence of different voltage levels on each of them.