Energy conversion circuit, control method based on energy conversion circuit, and vehicle

1 . An energy conversion circuit, comprising a primary bridge arm module, a resonant module, a secondary bridge arm module, and a control module; wherein the primary bridge arm module comprises a first bridge arm and a second bridge arm, and the secondary bridge arm module comprises a first secondary switch and a second secondary switch;

a bridge arm midpoint of the second bridge arm is connected to a first end of the resonant module, and a bridge arm midpoint of the first bridge arm is connected to a second end of the resonant module; a third end of the resonant module is connected to a first terminal of the second secondary switch, and a fourth end of the resonant module is connected to a first terminal of the first secondary switch; a first end of the first bridge arm is connected to a first end of the second bridge arm and a first direct current (DC) positive terminal, a second end of the first bridge arm is connected to a second end of the second bridge arm and a first DC negative terminal, a fifth end of the resonant module is connected to a second DC positive terminal, and a second terminal of the first secondary switch is connected to a second terminal of the second secondary switch and a second DC negative terminal; and

a drive signal for the first bridge arm, a drive signal for the second bridge arm, a drive signal for the first secondary switch, and a drive signal for the second secondary switch are controlled by the control module, to increase a voltage between the first DC positive terminal and the first DC negative terminal to a preset voltage; wherein during an increase in the voltage between the first DC positive terminal and the first DC negative terminal, switches in the secondary bridge arm module are turned off at zero current;

wherein the resonant module comprises a resonant inductor, a resonant capacitor, and a transformer; the transformer comprises a primary winding, a first secondary winding, and a second secondary winding;

the resonant inductor and the resonant capacitor both are connected in series with the primary winding, and the first secondary winding is connected in series with the second secondary winding; the resonant inductor, the resonant capacitor, and the primary winding are connected in series between the bridge arm midpoint of the first bridge arm and the bridge arm midpoint of the second bridge arm, a first end of the first secondary winding is connected to a second end of the second secondary winding and the second DC positive terminal, a second end of the first secondary winding is connected to the first terminal of the first secondary switch, and a first end of the second secondary winding is connected to the first terminal of the second secondary switch;

wherein the drive signal for the first bridge arm, the drive signal for the second bridge arm, the drive signal for the first secondary switch, and the drive signal for the second secondary switch being controlled by the control module, to increase the voltage between the first DC positive terminal and the first DC negative terminal to the preset voltage, and during the increase in the voltage between the first DC positive terminal and the first DC negative terminal, the switches in the secondary bridge arm module being turned off at zero current, comprise:

a gain of the energy conversion circuit being determined by the control module according to a first sampled voltage, a second sampled voltage, and a turns ratio of the transformer; the first sampled voltage being a sampled voltage between the first DC positive terminal and the first DC negative terminal, and the second sampled voltage being a sampled voltage between the second DC positive terminal and the second DC negative terminal;

on condition that the gain of the energy conversion circuit is less than 1, the drive signal for the first bridge arm, the drive signal for the second bridge arm, the drive signal for the first secondary switch, and the drive signal for the second secondary switch being controlled by the control module, to make switches in the primary bridge arm module operate in a synchronous rectification mode, and to make the switches in the secondary bridge arm module turned off at zero current; and

on condition that the gain of the energy conversion circuit is greater than or equal to 1, a phase-shift angle of the first bridge arm relative to the first secondary switch being determined by the control module as a first phase-shift angle, and a phase-shift angle of the second bridge arm relative to the first secondary switch being determined by the control module as a second phase-shift angle, to make the switches in the primary bridge arm module turned on at zero voltage and the switches in the secondary bridge arm module turned off at zero current, wherein the first phase-shift angle and the second phase-shift angle being equal, or the first phase-shift angle and the second phase-shift angle being not equal.

2 . The energy conversion circuit of claim 1 , wherein the drive signal for the first bridge arm, the drive signal for the second bridge arm, the drive signal for the first secondary switch, and the drive signal for the second secondary switch being controlled by the control module, to make the switches in the primary bridge arm module operate in the synchronous rectification mode, and to make the switches in the secondary bridge arm module turned off at zero current, comprises:

loop calculation being performed by the control module according to the first sampled voltage to obtain a voltage loop calculation result, and a signal frequency being determined by the control module according to the voltage loop calculation result; and

a frequency of the drive signal for the first bridge arm, a frequency of the drive signal for the second bridge arm, a frequency of the drive signal for the first secondary switch, and a frequency of the drive signal for the second secondary switch all being determined by the control module as the signal frequency, to make the switches in the primary bridge arm module operate in the synchronous rectification mode, and to make the switches in the secondary bridge arm module turned off at zero current.

3 . The energy conversion circuit of claim 1 , wherein the phase-shift angle of the first bridge arm relative to the first secondary switch being determined by the control module as the first phase-shift angle, and the phase-shift angle of the second bridge arm relative to the first secondary switch being determined by the control module as the second phase-shift angle, to make the switches in the primary bridge arm module turned on at zero voltage and the switches in the secondary bridge arm module turned off at zero current, comprises:

a primary-secondary side phase-shift angle being determined by the control module according to a sampled current and a reference current;

on condition that the first phase-shift angle and the second phase-shift angle are equal, the primary-secondary side phase-shift angle being determined as the first phase-shift angle;

on condition that the first phase-shift angle and the second phase-shift angle are not equal, according to the primary-secondary side phase-shift angle and the gain of the energy conversion circuit, the phase-shift angle of the first bridge arm relative to the first secondary switch being determined by the control module as the first phase-shift angle, and the phase-shift angle of the second bridge arm relative to the first secondary switch being determined by the control module as the second phase-shift angle, to make the switches in the primary bridge arm module turned on at zero voltage and the switches in the secondary bridge arm module turned off at zero current, wherein the sampled current being a sampled current between the second terminal of the first secondary switch and the second DC negative terminal.

4 . The energy conversion circuit of claim 1 , wherein the control module comprises a current control loop, a voltage control loop, a voltage-controlled oscillator (VCO), and a gain judgment and phase-shift/frequency modulation module;

the current control loop is configured to perform loop calculation on a result of a subtraction operation between the sampled current and the reference current, and output a primary-secondary side phase-shift angle;

the voltage control loop is configured to perform loop calculation on a result of a subtraction operation between the first sampled voltage and a reference voltage, and output a voltage loop calculation result;

the VCO is configured to calculate a signal frequency according to the voltage loop calculation result;

the gain judgment and phase-shift/frequency modulation module is configured to calculate the gain of the energy conversion circuit according to the first sampled voltage and the second sampled voltage;

the gain judgment and phase-shift/frequency modulation module is further configured to, on condition that the gain of the energy conversion circuit is less than 1, determine a frequency of the drive signal of the first bridge arm, a frequency of the drive signal of the second bridge arm, a frequency of the drive signal of the first secondary switch, and a frequency of the drive signal of the second secondary switch all as the signal frequency; and

the gain judgment and phase-shift/frequency modulation module is further configured to, on condition that the gain of the energy conversion circuit is greater than or equal to 1, determine both the first phase-shift angle and the second phase-shift angle as the primary-secondary side phase-shift angle, or calculate the first phase-shift angle and the second phase-shift angle according to the gain of the energy conversion circuit and the primary-secondary side phase-shift angle.

5 . The energy conversion circuit of claim 1 , wherein on condition that the gain of the energy conversion circuit is greater than or equal to 1, and the first phase-shift angle and the second phase-shift angle are not equal, the first phase-shift angle and the second phase-shift angle are determined according to the following formulas:

D

Φ

⁢

1

=

D

α

-

(

1

-

D

y

⁢

1

)

;

D

Φ

⁢

2

=

D

α

;

D

α

=

(

1

-

D

y

⁢

1

+

2

⁢

D

Φ

)

/

2

;

if

⁢

D

Φ

<

D

ΦB

,

then

⁢

D

y

⁢

1

=

k

×

(

2

⁢

D

Φ

+

1

)

/

(

2

-

k

)

;

if

⁢

D

Φ

≥

D

ΦB

,

then

⁢

D

y

⁢

1

=

[

2

×

D

Φ

×

(

1

-

k

)

+

2

⁢

k

-

1

]

/

k

;

where

⁢

in

⁢

k

=

1

/

Ge

;

D

ΦB

=

(

1

-

k

)

/

2

;

Ge

=

V

HV_FB

/

(

n

×

V

LV_FB

)

;

Ge is the gain of the energy conversion circuit, D Φ is the primary-secondary side phase-shift angle from loop calculation, D Φ1 is the first phase-shift angle, D Φ2 is the second phase-shift angle, n is the turns ratio of the transformer, V HV_FB is the first sampled voltage, V LV_FB is the second sampled voltage.

6 . The energy conversion circuit of claim 1 , wherein the signal frequency is positively correlated to the gain of the energy conversion circuit.

7 . A control method based on an energy conversion circuit, wherein the control method is applied to the energy conversion circuit of claim 1 , and the control method comprises:

controlling, by the control module, the drive signal for the first bridge arm, the drive signal for the second bridge arm, the drive signal for the first secondary switch, and the drive signal for the second secondary switch, to increase the voltage between the first DC positive terminal and the first DC negative terminal to the preset voltage;

wherein during the increase of the voltage between the first DC positive terminal and the first DC negative terminal, the switches in the secondary bridge arm module are turned off at zero current.

8 . A vehicle, comprising an energy conversion circuit and a bus capacitor, two terminals of the bus capacitor are respectively connected to the first DC positive terminal and the first DC negative terminal of the energy conversion circuit, and the energy conversion circuit is configured to charge the bus capacitor;

wherein the energy conversion circuit comprises a primary bridge arm module, a resonant module, a secondary bridge arm module, and a control module; wherein the primary bridge arm module comprises a first bridge arm and a second bridge arm, and the secondary bridge arm module comprises a first secondary switch and a second secondary switch;

a bridge arm midpoint of the second bridge arm is connected to a first end of the resonant module, and a bridge arm midpoint of the first bridge arm is connected to a second end of the resonant module; a third end of the resonant module is connected to a first terminal of the second secondary switch, and a fourth end of the resonant module is connected to a first terminal of the first secondary switch; a first end of the first bridge arm is connected to a first end of the second bridge arm and a first direct current (DC) positive terminal, a second end of the first bridge arm is connected to a second end of the second bridge arm and a first DC negative terminal, a fifth end of the resonant module is connected to a second DC positive terminal, and a second terminal of the first secondary switch is connected to a second terminal of the second secondary switch and a second DC negative terminal; and

a drive signal for the first bridge arm, a drive signal for the second bridge arm, a drive signal for the first secondary switch, and a drive signal for the second secondary switch are controlled by the control module, to increase a voltage between the first DC positive terminal and the first DC negative terminal to a preset voltage; wherein during an increase in the voltage between the first DC positive terminal and the first DC negative terminal, switches in the secondary bridge arm module are turned off at zero current;

wherein the resonant module comprises a resonant inductor, a resonant capacitor, and a transformer; the transformer comprises a primary winding, a first secondary winding, and a second secondary winding;

the resonant inductor and the resonant capacitor both are connected in series with the primary winding, and the first secondary winding is connected in series with the second secondary winding; the resonant inductor, the resonant capacitor, and the primary winding are connected in series between the bridge arm midpoint of the first bridge arm and the bridge arm midpoint of the second bridge arm, a first end of the first secondary winding is connected to a second end of the second secondary winding and the second DC positive terminal, a second end of the first secondary winding is connected to the first terminal of the first secondary switch, and a first end of the second secondary winding is connected to the first terminal of the second secondary switch;

wherein the drive signal for the first bridge arm, the drive signal for the second bridge arm, the drive signal for the first secondary switch, and the drive signal for the second secondary switch being controlled by the control module, to increase the voltage between the first DC positive terminal and the first DC negative terminal to the preset voltage, and during the increase in the voltage between the first DC positive terminal and the first DC negative terminal, the switches in the secondary bridge arm module being turned off at zero current, comprise:

a gain of the energy conversion circuit being determined by the control module according to a first sampled voltage, a second sampled voltage, and a turns ratio of the transformer; the first sampled voltage being a sampled voltage between the first DC positive terminal and the first DC negative terminal, and the second sampled voltage being a sampled voltage between the second DC positive terminal and the second DC negative terminal;

on condition that the gain of the energy conversion circuit is less than 1, the drive signal for the first bridge arm, the drive signal for the second bridge arm, the drive signal for the first secondary switch, and the drive signal for the second secondary switch being controlled by the control module, to make switches in the primary bridge arm module operate in a synchronous rectification mode, and to make the switches in the secondary bridge arm module turned off at zero current; and

on condition that the gain of the energy conversion circuit is greater than or equal to 1, a phase-shift angle of the first bridge arm relative to the first secondary switch being determined by the control module as a first phase-shift angle, and a phase-shift angle of the second bridge arm relative to the first secondary switch being determined by the control module as a second phase-shift angle, to make the switches in the primary bridge arm module turned on at zero voltage and the switches in the secondary bridge arm module turned off at zero current, wherein the first phase-shift angle and the second phase-shift angle being equal, or the first phase-shift angle and the second phase-shift angle being not equal.

9 . The vehicle of claim 8 , wherein the drive signal for the first bridge arm, the drive signal for the second bridge arm, the drive signal for the first secondary switch, and the drive signal for the second secondary switch being controlled by the control module, to make the switches in the primary bridge arm module operate in the synchronous rectification mode, and to make the switches in the secondary bridge arm module turned off at zero current, comprises:

loop calculation being performed by the control module according to the first sampled voltage to obtain a voltage loop calculation result, and a signal frequency being determined by the control module according to the voltage loop calculation result; and

a frequency of the drive signal for the first bridge arm, a frequency of the drive signal for the second bridge arm, a frequency of the drive signal for the first secondary switch, and a frequency of the drive signal for the second secondary switch all being determined by the control module as the signal frequency, to make the switches in the primary bridge arm module operate in the synchronous rectification mode, and to make the switches in the secondary bridge arm module turned off at zero current.

10 . The vehicle of claim 8 , wherein the phase-shift angle of the first bridge arm relative to the first secondary switch being determined by the control module as the first phase-shift angle, and the phase-shift angle of the second bridge arm relative to the first secondary switch being determined by the control module as the second phase-shift angle, to make the switches in the primary bridge arm module turned on at zero voltage and the switches in the secondary bridge arm module turned off at zero current, comprises:

a primary-secondary side phase-shift angle being determined by the control module according to a sampled current and a reference current;

on condition that the first phase-shift angle and the second phase-shift angle are equal, the primary-secondary side phase-shift angle being determined by the control module as the first phase-shift angle;

on condition that the first phase-shift angle and the second phase-shift angle are not equal, according to the primary-secondary side phase-shift angle and the gain of the energy conversion circuit, the phase-shift angle of the first bridge arm relative to the first secondary switch being determined by the control module as the first phase-shift angle, and the phase-shift angle of the second bridge arm relative to the first secondary switch being determined by the control module as the second phase-shift angle, to make the switches in the primary bridge arm module turned on at zero voltage and the switches in the secondary bridge arm module turned off at zero current, wherein the sampled current being a sampled current between the second terminal of the first secondary switch and the second DC negative terminal.

11 . The vehicle of claim 8 , wherein the control module comprises a current control loop, a voltage control loop, a voltage-controlled oscillator (VCO), and a gain judgment and phase-shift/frequency modulation module;

the current control loop is configured to perform loop calculation on a result of a subtraction operation between the sampled current and the reference current, and output a primary-secondary side phase-shift angle;

the voltage control loop is configured to perform loop calculation on a result of a subtraction operation between the first sampled voltage and a reference voltage, and output a voltage loop calculation result;

the VCO is configured to calculate a signal frequency according to the voltage loop calculation result;

the gain judgment and phase-shift/frequency modulation module is configured to calculate the gain of the energy conversion circuit according to the first sampled voltage and the second sampled voltage;

the gain judgment and phase-shift/frequency modulation module is further configured to, on condition that the gain of the energy conversion circuit is less than 1, determine a frequency of the drive signal of the first bridge arm, a frequency of the drive signal of the second bridge arm, a frequency of the drive signal of the first secondary switch, and a frequency of the drive signal of the second secondary switch all as the signal frequency; and

the gain judgment and phase-shift/frequency modulation module is further configured to, on condition that the gain of the energy conversion circuit is greater than or equal to 1, determine both the first phase-shift angle and the second phase-shift angle as the primary-secondary side phase-shift angle, or calculate the first phase-shift angle and the second phase-shift angle according to the gain of the energy conversion circuit and the primary-secondary side phase-shift angle.

12 . The vehicle of claim 8 , wherein on condition that the gain of the energy conversion circuit is greater than or equal to 1, and the first phase-shift angle and the second phase-shift angle are not equal, the first phase-shift angle and the second phase-shift angle are determined according to the following formulas:

D

Φ

⁢

1

=

D

α

-

(

1

-

D

y

⁢

1

)

;

D

Φ

⁢

2

=

D

α

;

D

α

=

(

1

-

D

y

⁢

1

+

2

⁢

D

Φ

)

/

2

;

if

⁢

D

Φ

<

D

ΦB

,

then

⁢

D

y

⁢

1

=

k

×

(

2

⁢

D

Φ

+

1

)

/

(

2

-

k

)

;

if

⁢

D

Φ

≥

D

ΦB

,

then

⁢

D

y

⁢

1

=

[

2

×

D

Φ

×

(

1

-

k

)

+

2

⁢

k

-

1

]

/

k

;

where

⁢

in

⁢

k

=

1

/

Ge

;

D

ΦB

=

(

1

-

k

)

/

2

;

Ge

=

V

HV_FB

/

(

n

×

V

LV_FB

)

;

Ge is the gain of the energy conversion circuit, D Φ is the primary-secondary side phase-shift angle from loop calculation, D Φ1 is the first phase-shift angle, D Φ2 is the second phase-shift angle, n is the turns ratio of the transformer, V HV_FB is the first sampled voltage, V LV_FB is the second sampled voltage.

13 . The vehicle of claim 8 , wherein the signal frequency is positively correlated to the gain of the energy conversion circuit.