Bi-directional isolated DC-DC converter for the electrification of transportation

• US 10,483,862 B1
• Filed: 10/25/2018
• Issued: 11/19/2019
• Est. Priority Date: 10/25/2018
• Status: Active Grant

• Current Assignee: Vanner, Inc. (Vanner Holdings, Inc.)
• Original Assignee: Vanner, Inc. (Vanner Holdings, Inc.)
• Inventors: Cook, Alexander, Isurin, Alexander
• Primary Examiner(s): Behm, Harry R
• Application Number:
  US16/171,038
• Time in Patent Office: 390 Days
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 1/008 Plural converter units for generating at two or more independent and non-parallel outputs, e.g. systems with plural point of load switching regulators
• CPC Class Codes: H02M 1/088 for the simultaneous control of series or parallel connected semiconductor devices
• CPC Class Codes: H02M 1/44 Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
• CPC Class Codes: H02M 3/33561 having more than one ouput with independent control
• CPC Class Codes: H02M 3/33584 Bidirectional converters
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A topology for an isolated, bi-directional, DC-DC converter, that provides step-up and step-down functionality, with a reduced transformer turns ratio, allows a simplified transformer design with reduced cost and increased efficiency. This topology also has a very small level of re-circulating current, relative to other topologies regarding cost and performance.

Claims

1. A bi-directional DC-DC converter (20) comprising:

a first stage (30) comprising;

a first port (22) connected between a first node (N1) and ground;

the first port (22) being bi-directionally operable as an output or an input;

the first port (22) being operatively connected to a primary winding (80) of a first transformer (Tr1);

a second stage (40) comprising;

a second port (24) connected between seventh and eighth nodes (N7), (N8);

the second port (24) being bi-directionally operable as an output or an input;

the second port (24) being operatively connected to a secondary winding (82) of the first transformer (Tr1);

the secondary winding of the first transformer having first and second terminals;

a fifth switch (S5) having first and second terminals

the fifth switch having a body diode,

an anode of the body diode of the fifth switch being connected to the second terminal of the fifth switch,

a cathode of the body diode of the fifth switch being connected to the first terminal of the fifth switch;

a sixth switch (S6) having first and second terminals

the sixth switch having a body diode,

an anode of the body diode of the sixth switch being connected to the second terminal of the sixth switch,

a cathode of the body diode of the sixth switch being connected to the first terminal of the sixth switch;

a seventh switch (S7) having first and second terminals

the seventh switch having a body diode,

an anode of the body diode of the seventh switch being connected to the second terminal of the seventh switch,

a cathode of the body diode of the seventh switch being connected to the first terminal of the seventh switch;

an eighth switch (S8) having first and second terminals

the eighth switch having a body diode,

an anode of the body diode of the eighth switch being connected to the first terminal of the eighth switch,

a cathode of the body diode of the eighth switch being connected to the second terminal of the eighth switch;

a first resonant inductor (Lr1) having first and second terminals;

a first resonant capacitor (Cr1) having first and second terminals;

a second resonant capacitor (Cr2) having first and second terminals;

a third resonant capacitor (Cr3) having first and second terminals;

a fourth resonant capacitor (Cr4) having first and second terminals;

the first terminal of the fifth switch (S5) being connected to the seventh node (N7), the second terminal of the fifth switch (S5) being connected to a sixth node (N6);

the first terminal of the sixth switch (S6) being connected to the sixth node (N6);

the second terminal of the sixth switch (S6) being connected to the eighth node;

the first terminal of the seventh switch (S7) being connected to a tenth node (N10);

the second terminal of the seventh switch (S7) being connected to an eleventh node (N11);

the first terminal of the eighth switch (S8) being connected to the eleventh node (N11);

the second terminal of the eighth switch (S8) being connected to a twelfth node (N12);

the first terminal of the secondary winding (82) of the first transformer (Tr1) being connected to the sixth node (N6);

the second terminal of the secondary winding (82) of the first transformer (Tr1) being connected to a ninth node (N9);

the first terminal of the first resonant inductor (Lr1) being connected to the ninth node (N9);

the second terminal of the first resonant inductor (Lr1) being connected to the tenth node (N10);

the first terminal of the first resonant capacitor (Cr1) being connected to the seventh node (N7);

the second terminal of the first resonant capacitor (Cr1) being connected to the twelfth node (N12);

the first terminal of the second resonant capacitor (Cr2) being connected to the twelfth node (N12);

the second terminal of the second resonant capacitor (Cr2) being connected to the eighth node (N8);

the first terminal of the third resonant capacitor (Cr3) being connected to the seventh node (N7);

the second terminal of the third resonant capacitor (Cr3) being connected to the tenth node (N10);

the first terminal of the fourth resonant capacitor (Cr4) being connected to the tenth node (N10);

the second terminal of the fourth resonant capacitor (Cr4) being connected to the eighth node (N8).

2. The bi-directional DC-DC converter (20) of claim 1 further comprising:

the switch (S2) being bi-directional.

3. The bi-directional DC-DC converter (20) of claim 1 further comprising:

the switch (S2) being bi-directional;

and the switch (S4) being bi-directional.

4. A method for DC-DC voltage conversion comprising the steps of:

obtaining the bi-directional DC-DC converter of claim 3,

wherein a first load (RL1) is connected between the seventh and eighth nodes (N7), (N8),

further wherein a first voltage source (V1) is connected between the first node (N1) and ground,

further wherein the capacitances of the third and fourth resonant capacitors being relatively less than the capacitances of the first and second resonant capacitors;

switching switches (S1) and (S3) in an alternating manner according to a pre-determined duty cycle and frequency, wherein switch (S2) is switched complementary to switch (S1), and switch (S4) is switched complementary to switch (S3);

maintaining switches (S5) and (S6) in a non-conducting state;

at a time (t0),

switches (S2) and (S3) are turned on,

switches (S1) and (S4) are turned off,

switch (S7) is on,

and switch (S8) is off;

then at a time (t1),

switch (S7) is turned off,

and switch (S8) is turned on;

then at a time (t3),

switches (S2) and (S3) are turned off,

and switches (S1) and (S4) are turned on;

then at a time (t4),

switch (S7) is turned on,

and switch (S8) is turned off.

5. The method of claim 4 further comprising:

the pre-determined duty cycle is 50%.

6. The method of claim 4 further comprising:

selecting component values, timing, and duty cycle such that;

during first and second half-cycles, the second half cycle being substantially identical to the first half-cycle but 180 degrees out of phase thereto,

during the first half-cycle occurring between the time (t0) and the time (t3), a current flowing through the first resonant inductor (Lr1) from approximately zero, and flowing in an approximately semi-sinusoidal waveform between the time (t0) and a time (t2), and being approximately zero between the time (t2) and the time (t3);

during the first half-cycle,

the second capacitor (C2) is charged via the second inductor (L2), and the second switch (S2), and

the first capacitor (C1) is discharged through the third switch (S3), the primary winding of the first transformer (Tr1), and the second switch (S2), such that

when the current in the first capacitor (C1) reaches a maximum, the current via switch (S2) will have reversed direction;

between the time (a) and the time (t2),

the current flowing through the first load (RL1) decays linearly, and reaches zero at the time (t2),

between the time (t2) and the time (t3),

only magnetizing current flows through the first transformer (Tr1).

7. A method for DC-DC voltage conversion comprising the steps of:

obtaining the bi-directional DC-DC converter of claim 3,

wherein a second load (RL2) is connected between the first node (N1) and ground,

further wherein a second voltage source (V2) is connected between the seventh and eighth nodes (N7) &

(N8);

maintaining switches (S7) and (S8) in a conducting state;

switching switches (S5) and (S6) in an alternating manner according to a pre-determined duty cycle and frequency;

at a time (t0),

switch (S1) is off,

switch (S2) is on,

switch (S5) is turned off,

switch (S6) is turned on,

switch (S3) is turned on,

switch (S4) is turned off,

at a time (t1),

switch (S3) is turned off,

and switch (S4) is turned on;

at a time (t2),

switch (S5) is turned on,

switch (S6) is turned off,

switch (S1) is turned on,

and switch (S2) is turned off;

at a time (t3),

switch (S1) is turned off,

switch (S2) is turned on.

8. The method of claim 7 further comprising:

the pre-determined duty cycle is 50%, and the commutation frequency is 20% below the tank resonant frequency.

9. The method of claim 7 further comprising:

selecting component values, timing, and duty cycle such that;

at the time (t0),

a current flowing through the first resonant inductor (Lr1) starts from zero and flows in a positive direction in a semi-sinusoidal waveform and reaches zero at the time (t1),

the first capacitor (C1) charges via switch (S3), the secondary of the first transformer (Tr1), and the switch (S2),

the second capacitor (C2) discharges to the second load (RL2) via the second inductor (L2) and the switch (S2);

at the time (t1),

the first capacitor (C1) is substantially charged,

the first and second capacitors (C1) and (C2) discharge to the second load (RL2) during at least a portion of the interval between the times (t0) and (t1);

at the time (t2),

a current flowing through the first resonant inductor (Lr1) starts from zero and flows in a negative direction in a semi-sinusoidal waveform and reaches zero at the time (t3),

the second capacitor (C2) begins to charge;

at the time (t3),

the second capacitor (C2) is substantially charged.