DCDC output voltage control method and control system for hybrid electric vehicle

Patent metadata

Field	Value
Publication number	US-12539839-B2
Application number	US-202118287920-A
Country	US
Kind code	B2
Filing date	Aug 10, 2021
Priority date	Aug 10, 2021
Publication date	Feb 3, 2026
Grant date	Feb 3, 2026

Abstract

A DCDC output voltage control method and control system for a hybrid electric vehicle are provided. The method includes: when a DCDC converter is in a buck operation mode, determining whether the vehicle is in a high power output demand state or an abnormal engine flame-out state; if so, setting the output voltage of the DCDC converter to a normal target voltage; otherwise, determining whether a low-voltage load has a charging voltage boost demand, and when the low-voltage load has the charging voltage boost demand and the power of a high-voltage battery is greater than a power threshold, setting the output voltage of the DCDC converter according to the voltage level corresponding to the charging voltage boost demand, to meet the charging demand of the low-voltage load. The fuel economy of a hybrid power assembly system can be optimized.

First claim

What is claimed is:

1 . A DCDC output voltage control method for a hybrid electric vehicle, the vehicle comprising a DCDC converter for converting a voltage of a high-voltage battery into a low voltage used for a low-voltage load of the vehicle in a buck operation mode and outputting the low voltage, the method comprising:
when the DCDC converter is in the buck operation mode, determining whether the vehicle is in a high power output demand state or an abnormal engine flame-out state; if so, setting an output voltage of the DCDC converter to a normal target voltage, so as to control the DCDC converter to output according to the normal target voltage; otherwise, determining whether the low-voltage load has a charging voltage boost demand, and when the low-voltage load has the charging voltage boost demand and an electric quantity of the high-voltage battery is greater than an electric quantity threshold, setting the output voltage of the DCDC converter according to a voltage level corresponding to the charging voltage boost demand, so as to meet a charging demand of the low-voltage load.

2 . The DCDC output voltage control method according to claim 1 , wherein before the step of, when the DCDC converter is in the buck operation mode, determining whether the vehicle is in a high power output demand state or an abnormal engine flame-out state, the method further comprises:
determining whether the vehicle is in a DCDC enable state; and when the vehicle is in the enable state and receives a buck request instruction, controlling the DCDC converter to prepare for voltage conversion, performing timing, and controlling the DCDC converter to switch to the buck operation mode when the time arrives at a preset delay time.

3 . The DCDC output voltage control method according to claim 2 , wherein the step of determining whether the vehicle is in a DCDC enable state comprises:
determining that the DCDC converter is in a pre-enable state when the high-voltage battery of the vehicle is in a state of being able to supply power, the vehicle receives a start request instruction, the high-voltage battery is in a state of being able to maintain a preset electric quantity, the DCDC converter is in a state of being able to normally transmit and receive signals, and a high-voltage system is not faulty; and determining that the DCDC converter is in the enable state when the DCDC converter is in the pre-enable state, an ignition signal is received and it is determined that a motor of the vehicle is not faulty.

4 . The DCDC output voltage control method according to claim 1 , wherein
the high power output demand state comprises at least one of an initiation start state, a full-throttle acceleration state, an operating high-throttle start state and a crawling start in-gear state.

5 . The DCDC output voltage control method according to claim 4 , wherein the step of determining whether the vehicle is in a high power output demand state comprises:
determining that the vehicle is in the initiation start state when, in a same driving cycle, a first start time of an engine of the vehicle is less than a first limit or a non-first start time thereof is less than a second limit, wherein the first limit is greater than the second limit.

6 . The DCDC output voltage control method according to claim 4 , wherein the step of determining whether the vehicle is in a high power output demand state comprises:
determining that the vehicle is in the full-throttle acceleration state when an opening of a throttle pedal of the vehicle is greater than a first opening limit, the vehicle is in a forward gear or a reverse gear, and the time when the opening of the throttle pedal is greater than the first opening limit is less than a third limit.

7 . The DCDC output voltage control method according to claim 4 , wherein the step of determining whether the vehicle is in a high power output demand state comprises:
determining that the vehicle is in the operating high-throttle start state when the engine of the vehicle is in an operating state, a vehicle speed is less than a starting vehicle speed threshold, a reserve torque of the engine is less than a torque threshold, an opening of a throttle pedal of the vehicle is greater than a second opening limit, a difference between a maximum torque of the engine and a driver request torque is less than a difference threshold, and a current power of an air condition compressor is greater than a power limit.

8 . The DCDC output voltage control method according to claim 4 , wherein the step of determining whether the vehicle is in a high power output demand state comprises:
determining that the vehicle is in the crawling start in-gear state when the engine of the vehicle is in an operating state, a starting time is less than a fourth limit, a vehicle speed is less than a starting vehicle speed threshold, a reserve torque of the engine is less than a torque threshold, opening information of a throttle pedal is not received, and the vehicle is in a forward gear or a reverse gear.

9 . The DCDC output voltage control method according to claim 1 , wherein the step of determining whether the vehicle is in an abnormal engine flame-out state comprises:
determining that the vehicle is in the abnormal engine flame-out state when the engine of the vehicle is in an operating state, a rotation speed of the engine is less than a target idle speed and the absolute value of a difference between the two is greater than a rotation speed difference limit, a rotation speed acceleration of the engine is negative and the absolute value of the rotation speed acceleration is less than an acceleration limit, and a predicted rotation speed of the engine is less than a flame-out rotation speed threshold.

10 . The DCDC output voltage control method according to claim 1 , wherein the step of determining whether the low-voltage load has a charging voltage boost demand comprises:
determining whether a catalytic converter of the vehicle is in a rapid heating demand state; determining whether an oil pump of the vehicle is in a high load demand state; determining whether a fan of the vehicle is in a high load state; and determining that the low-voltage load has the charging voltage boost demand when one or more conditions of the catalytic converter being in the rapid heating demand state, the oil pump being in the high load demand state, and the fan being in the high load state occur.

11 . The DCDC output voltage control method according to claim 10 , wherein the step of determining whether a catalytic converter of the vehicle is in a rapid heating demand state comprises:
determining that the catalytic converter is in the rapid heating demand state when the temperature of a coolant in the engine of the vehicle is higher than a temperature threshold, an upstream exhaust temperature of the catalytic converter is reliable, and the exhaust temperature is lower than an air temperature threshold.

12 . The DCDC output voltage control method according to claim 10 , wherein the step of determining whether an oil pump of the vehicle is in a high load demand state comprises:
determining that the oil pump is in the high load demand state when a load of the oil pump is greater than a load threshold.

13 . The DCDC output voltage control method according to claim 10 , wherein the step of determining whether a fan of the vehicle is in a high load state comprises:
determining that the fan is in the high load state when an opening of the fan is greater than an opening threshold.

14 . The DCDC output voltage control method according to claim 10 , wherein the

Assignees

• Ningbo Geely Royal Engine Components Co Ltd
• Aurobay Tech Co Ltd
• Geely Holding Group Co Ltd

Inventors

• Jing Junchao
• Liu Yiqiang
• Huang Weishan
• Yang Jun
• Yu Xuemei
• Wang Ruiping
• Scholten Ingo

Classifications

• B60L2210/14

  Boost converters · CPC title

• B60L2210/12

  Buck converters · CPC title

• B60L50/16

  with provision for separate direct mechanical propulsion · CPC title

• B60W10/30 Primary

  including control of auxiliary equipment, e.g. air-conditioning compressors or oil pumps · CPC title

• B60L2260/12

  of combustion engines · CPC title