Techniques for synchronous rectification control of DC-DC converters in electrified vehicles

Patent metadata

Field	Value
Publication number	US-9315166-B2
Application number	US-201414323563-A
Country	US
Kind code	B2
Filing date	Jul 3, 2014
Priority date	Jul 12, 2013
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

Abstract

Techniques are presented for synchronous rectification control (SRC) of a DC-DC converter in an electrified vehicle (EV) can include determining a required output current for the DC-DC converter based on a secondary voltage of a secondary battery system of the EV, the DC-DC converter being configured to convert a primary voltage from a primary battery system of the EV to the secondary voltage. The techniques can include determining, at the controller, a switching frequency for the DC-DC converter that causes the DC-DC converter to output the required output current. The techniques can include determining turn-on and turn-off delays of the DC-DC converter based on the required output current and the switching frequency using one or more look-up tables. The techniques can also include controlling the DC-DC converter efficiency based on the turn-on and turn-off delays.

First claim

What is claimed is:

1. A method, comprising:
determining, at a controller of an electrified vehicle (EV), the controller including one or more processors, a required output current for a DC-DC converter based on a secondary voltage of a secondary battery system of the EV, the DC-DC converter being configured to convert a primary voltage from a primary battery system of the EV to the secondary voltage;
determining, at the controller, a switching frequency for the DC-DC converter that causes the DC-DC converter to output the required output current;
determining, at the controller, turn-on and turn-off delays of the DC-DC converter based on the required output current and the switching frequency using one or more look-up tables; and
controlling, by the controller, the DC-DC converter based on the turn-on and turn-off delays.

2. The method of claim 1 , further comprising determining, at the controller, an input current, an output current, an input voltage, and an output voltage of the DC-DC converter in response to controlling the DC-DC converter based on the turn-on and turn-off delays.

3. The method of claim 2 , further comprising calculating, at the controller, an efficiency of the DC-DC converter based on the input current, the output current, the input voltage, and the output voltage of the DC-DC converter.

4. The method of claim 3 , wherein the efficiency of the DC-DC converter is calculated as:

η
=

V
out

×

I
out

V
in

×

I
in

,

where η represents the efficiency of the DC-DC converter, V out and I out represent the output voltage and the output current, respectively, and V in and I in represent the input voltage and the input current, respectively.

5. The method of claim 3 , further comprising comparing, at the controller, the efficiency to a maximum efficiency of the DC-DC converter.

6. The method of claim 5 , further comprising selectively adjusting, at the controller, at least one of the turn-on and turn-off delays based on the comparison to obtain at least one of a modified turn-on delay and a modified turn-off delay.

7. The method of claim 6 , wherein selectively adjusting at least one of the turn-on and turn-off delays based on the comparison includes:
adjusting, at the controller, at least one of the turn-on and turn-off delays when the efficiency is less than the maximum efficiency to obtain the at least one of the modified turn-on delay and the modified turn-off delay; and
adjusting, at the controller, neither of the turn-on and turn-off delays when the efficiency is at the maximum efficiency.

8. The method of claim 7 , further comprising controlling, by the controller, the DC-DC converter based on the at least one of the modified turn-on delay and the modified turn-off delay.

9. The method of claim 6 , further comprising storing, at the controller, the turn-on delay, wherein selectively adjusting at least one of the turn-on and turn-off delays based on the comparison includes selectively adjusting the turn-off delay based on the comparison to obtain the modified turn-off delay.

10. The method of claim 8 , wherein selectively adjusting the turn-off delay based on the comparison includes:
adjusting, at the controller, the turn-off delay when the efficiency is less than the maximum efficiency to obtain the modified turn-off delay; and
not adjusting, at the controller, the turn-off delay when the efficiency is at the maximum efficiency.

11. The method of claim 10 , further comprising controlling, by the controller, the DC-DC converter based on the turn on-delay and the modified turn-off delay.

12. The method of claim 1 , wherein the turn-on delay is determined using a first look-up table relating delay to current and frequency, and wherein the turn-off delay is determined using a second look-up table relating delay to current and frequency.

13. The method of claim 1 , wherein the DC-DC converter is a inductor-inductor-capacitor (LLC) half-bridge DC-DC converter including a plurality of transistors controlled by pulse-width modulated (PWM) control signals.

14. The method of claim 1 , wherein the primary battery system is a battery pack including a plurality of lithium-ion battery cells, and wherein the primary voltage is within a range from 220 volts to 400 volts.

15. The method of claim 1 , wherein the secondary battery system is a lead-acid battery, and wherein the secondary voltage is within a range from 6.5 volts to 16 volts.

16. A method, comprising:
determining, at a controller of an electrified vehicle (EV), the controller including one or more processors, a required output current for a DC-DC converter based on a secondary voltage of a secondary battery system of the EV, the DC-DC converter being configured to convert a primary voltage from a primary battery system of the EV to the secondary voltage for at least one of recharging the secondary battery system of the EV and powering low-voltage components of the EV;
determining, at the controller, a switching frequency for the DC-DC converter that causes the DC-DC converter to output the required output current;
determining, at the controller, turn-on and turn-off delays of the DC-DC converter based on the required output current and the switching frequency using one or more look-up tables;
controlling, by the controller, the DC-DC converter based on the turn-on and turn-off delays;
determining, at the controller, input current, output current, input voltage, and output voltage of the DC-DC converter;
determining, at the controller, an efficiency of the DC-DC converter based on the input current, the output current, the input voltage, and the output voltage of the DC-DC converter;
comparing, at the controller, the efficiency of the DC-DC converter to a maximum efficiency of the DC-DC converter; and
selectively adjusting, at the controller, at least one of the turn-on and turn-off delays of the DC-DC converter based on the comparison to obtain at least one of a modified turn-on delay and a modified turn-off delay.

17. The method of claim 16 , further comprising controlling, by the controller, the DC-DC converter based on the at least one of the modified turn-on delay and the modified turn-off delay.

18. The method of claim 16 , wherein the efficiency of the DC-DC converter is calculated as:

η
=

V
out

×

I
out

V
in

×

I
in

Assignees

• Nie zhong
• Zhang Mengyang
• Krozek Dennis
• Householder Fred A
• Bai Hua
• Guo Wei
• Duan Chen
• Fca Us Llc
• Kettering University

Inventors

• Nie zhong
• Zhang Mengyang
• Krozek Dennis
• Householder Fred A
• Bai Hua
• Guo Wei
• Duan Chen

Classifications

• B60L2210/12

  Buck converters · CPC title

• B60L2240/526

  Operating parameters · CPC title

• Y02T10/92

  Energy efficient charging or discharging systems for batteries, ultracapacitors, supercapacitors or double-layer capacitors specially adapted for vehicles · CPC title

• B60L1/00

  Supplying electric power to auxiliary equipment of vehicles (circuit arrangements for charging batteries H02J7/00) · CPC title

• B60L50/13

  using AC generators and AC motors · CPC title