Charging and discharging device, methods of battery charging and discharging, and charging and discharging system

Patent metadata

Field	Value
Publication number	US-11685289-B2
Application number	US-202117562286-A
Country	US
Kind code	B2
Filing date	Dec 27, 2021
Priority date	Jul 29, 2021
Publication date	Jun 27, 2023
Grant date	Jun 27, 2023

Abstract

Embodiments of the present application provide a charging and discharging device. The charging and discharging device includes an AC/DC converter, a first DC/DC converter, a second DC/DC converter and a control unit. The control unit is used to: receive a first charging request, the first charging request including a first charging voltage and a first charging current; set output power of the first DC/DC converter based on the first charging voltage and the first charging current; turn on the second DC/DC converter if an SOC of the energy storage unit is greater than a first threshold to charge the battery by the energy storage unit; and adjust output power of the second DC/DC converter, so as to enable a voltage difference between a bus voltage and a bus balance voltage of the charging and discharging device to be less than or equal to a preset value.

First claim

What is claimed is:

1. A charging and discharging device, comprising an alternating current/direct current (AC/DC) converter, a first direct current/direct current (DC/DC) converter, a second DC/DC converter and a control unit, wherein one end of the second DC/DC converter is connected between the first DC/DC converter and the AC/DC converter and the other end of the second DC/DC converter is connected to an energy storage unit; and
the control unit is configured to:
receive a first charging request transmitted by a battery management system (BMS) of a battery, the first charging request comprising a first charging voltage and a first charging current,
set output power of the first DC/DC converter as first output power of the first DC/DC converter based on the first charging voltage and the first charging current,
acquire a state of charge (SOC) of the energy storage unit,
turn on the second DC/DC converter under the condition that the SOC of the energy storage unit is greater than a first threshold, to charge the battery by the energy storage unit through the first DC/DC converter and the second DC/DC converter,
acquire a bus voltage of the charging and discharging device in real time, and
adjust output power of the second DC/DC converter to the first output power of the second DC/DC converter under the condition that the battery is charged by the energy storage unit, the bus voltage is less than a bus balance voltage and a difference between the bus voltage and the bus balance voltage exceeds a preset value, the first output power of the second DC/DC converter being less than or equal to a maximum output power of the second DC/DC converter,
wherein the difference between the bus voltage and the bus balance voltage is less than or equal to the preset value after the output power of the second DC/DC converter is adjusted to the first output power of the second DC/DC converter.

2. The charging and discharging device according to claim 1 , wherein the control unit is further configured to:
adjust the output power of the second DC/DC converter to the maximum output power of the second DC/DC converter under the condition that the battery is charged by the energy storage unit, the bus voltage is less than the bus balance voltage and the difference between the bus voltage and the bus balance voltage exceeds the preset value turn on the AC/DC converter, and adjust the output power of the AC/DC converter to the first output power of the AC/DC converter, to charge the battery by an alternating current power supply through the AC/DC converter and the first DC/DC converter simultaneously,
wherein the difference between the bus voltage and the bus balance voltage is less than or equal to the preset value after the output power of the second DC/DC converter is adjusted to the maximum output power of the second DC/DC converter and the output power of the AC/DC converter is adjusted to the first output power of the AC/DC converter.

3. The charging and discharging device according to claim 2 , wherein the control unit is further configured to:
receive a second charging request transmitted by the BMS, the second charging request comprising a second charging voltage and a second charging current;
set the output power of the first DC/DC converter as second output power of the first DC/DC converter based on the second charging voltage and the second charging current, the second output power of the first DC/DC converter being less than the first output power of the first DC/DC converter; and
maintain the output power of the second DC/DC converter as the maximum output power of the second DC/DC converter and adjust the first output power of the AC/DC converter to be reduced to the second output power of the AC/DC converter under the condition that the battery is charged by the energy storage unit, the bus voltage is greater than the bus balance voltage and the difference between the bus voltage and the bus balance voltage exceeds the preset value and the alternating current power supply,
wherein the difference between the bus voltage and the bus balance voltage is less than or equal to the preset value after the output power of the second DC/DC converter is adjusted to the maximum output power of the second DC/DC converter and the output power of the AC/DC converter is adjusted to the second output power of the AC/DC converter.

4. The charging and discharging device according to claim 3 , wherein the control unit is further configured to:
adjust the first output power of the AC/DC converter to zero and adjust the output power of the second DC/DC converter from the maximum output power of the second DC/DC converter to the second output power of the second DC/DC converter under the condition that the bus voltage is greater than the bus balance voltage and the difference between the bus voltage and the bus balance voltage exceeds the preset value,
wherein the difference between the bus voltage and the bus balance voltage is less than or equal to the preset value after the output power of the second DC/DC converter is adjusted to the second output power of the second DC/DC converter.

5. The charging and discharging device according to claim 1 , wherein the control unit is further configured to:
turn on the AC/DC converter under the condition that the SOC of the energy storage unit is greater than a second threshold and less than the first threshold, so as to charge the battery by the alternating current power supply through the first DC/DC converter and the AC/DC converter; and
adjust the output power of the AC/DC converter to third output power of the AC/DC converter under the condition that the bus voltage is less than the bus balance voltage and the difference between the bus voltage and the bus balance voltage exceeds the preset value in the process of charging the battery by the alternating current power supply, the third output power of the AC/DC converter being less than or equal to the maximum output power of the AC/DC converter, and
wherein the difference between the bus voltage and the bus balance voltage is less than or equal to the preset value after the output power of the AC/DC converter is adjusted to the third output power of the AC/DC converter.

6. The charging and discharging device according to claim 5 , wherein the control unit is further configured to:
adjust the output power of the AC/DC converter to the maximum output power of the second DC/DC converter, turn on the second DC/DC converter, and adjust the output power of the second DC/DC converter to the third output power of the second DC/DC converter under the condition that the bus voltage is less than the bus balance voltage and the difference between the bus voltage and the bus balance voltage exceeds the preset value in the process of charging the battery by the alternating current power supply, so as to charge the battery by the energy storage unit through the first DC/DC converter and the second DC/DC converter,
wherein the difference between the bus voltage and the bus balance voltage is less than the preset value after the output power of the AC/DC converter is adjusted to the maximum output power of the AC/DC converter and the second DC/DC converter is adjusted to the third output power of the second DC/DC converter.

7. The charging and discharging device according to claim 6 , wherein the control unit is further configured to:
receive a third charging request transmitted by the BMS, the third charging request comprising s a third charging voltage and a third charging current;
set the output power of the first DC/DC converter as the third output power of the first DC/DC converter based on the third charging voltage and the third charging current, the third output power of the first DC/DC converter being

Assignees

• Contemporary Amperex Technology Co Ltd

Inventors

• Gao Jinfeng
• Qi Chen
• Zuo Xiyang
• Huang Xiaojian

Classifications

• H02J7/90

  Regulation of charging or discharging current or voltage · CPC title

• H02J2105/37

  exchanging power with electric vehicles [EV] or with hybrid electric vehicles [HEV] · CPC title

• H02J7/96

  in response to battery voltage · CPC title

• H02J7/977

  of the battery · CPC title

• H02J7/971

  the charge cycle being controlled or terminated in response to non-electric parameters · CPC title