Isolated DC power supply based on class-e inverter and its design method
View Patent ↗The invention relates to an isolated DC power supply utilizing a Class-E inverter and its design method, within the field of power electronics and high voltage technology. This DC power supply comprises a DC power source, a Class-E inverter, a CL network, a series resonant unit, and a rectifier circuit, featuring two structures. It is characterized by a single switching device and a stable output voltage that does not vary with load changes. This resolves stability issues commonly associated with isolated DC power supplies based on Class-E inverters. The invention also introduces a design method that includes calculating core parameters like capacitors and inductors, ensuring optimal component selection. Offering strong isolation, constant voltage output, high efficiency, and cost-effectiveness, this DC power supply is ideal for use in wireless power transfer systems, high-frequency power supplies, and isolated sensor and gate driver power supplies.
1 . A design method of an isolated DC power supply based on Class-E inverter, wherein,
the isolated DC power supply based on Class-E inverter comprises: a DC power supply, a Class-E inverter, a CL network, a series resonant unit, and a rectifier circuit;
the Class-E inverter comprises: an input inductor (L e ), a power switching device (S), and a parallel capacitor (C 0 );
the CL network comprises: a network inductor (L r ) and a network capacitor (C r );
the series resonant unit comprises: a transmitting inductor (L T ), a transmitting capacitor (C T ), a transmitting inductor parasitic resistance (R 1 ), a receiving inductor (L R ), a receiving capacitor (C R ), and a receiving inductor parasitic resistance (R 2 ), and M is a mutual inductor between the transmitting inductor (L T ) and the receiving inductor (L R );
the rectifier circuit comprises: a rectifier circuit and a filter capacitor (C out ), and the rectifier circuit rectifies a high-frequency AC to a DC required by a load;
and wherein the isolated DC power supply is constructed by any one of two types of connections: Type I or Type II:
in the Type I, an input port of the Class-E inverter is connected to the DC power supply, an output port of the Class-E inverter is connected to an input port of the CL network, an output port of the CL network is connected to an input port of the series resonant unit, an output port of the series resonant unit is connected to an input port of the rectifier circuit, an output port of the rectifier circuit is connected to a load;
in the Type II, the input port of the Class-E inverter is connected to the DC power supply, the output port of the Class-E inverter is connected to the input port of the series resonant unit, the output port of the series resonant unit is connected to the input port of the CL network, the output port of the CL network is connected to the input port of the rectifier circuit, the output port of the rectifier circuit is connected to the load;
wherein the design method comprising:
S1. designing values of input voltage (V in ), output voltage (V out ), maximum power (P max ), and system operating angular frequency (ω) as required; determining a value of a self-inductor and a mutual inductor of a transmitting port and a receiving port according to a physical structure of a selected transmission medium;
S2. depending on the Type I or the Type II, determining a voltage transformation ratio of the network inductor (L r ) according to Formula (6) or Formula (7):
V
out
V
in
=
1.35
M
L
r
,
(
6
)
V
out
V
in
=
1.35
L
r
M
;
(
7
)
S3. determining values of the network capacitor (C r ), the receiving capacitor (C R ), and the transmitting capacitor (C r ) according to the system operating angular frequency (ω), and calculation expressions are as follows:
C
r
=
1
ω
2
L
r
,
(
8
)
C
R
=
1
ω
2
L
R
,
(
9
)
C
T
=
1
ω
2
L
T
;
(
10
)
S4. determining the input inductor (L e ) according to the maximum power (P max ) of a system, and a calculation expression is as follows:
L
e
=
1.33
V
in
2
ω
P
max
;
(
11
)
S5. determining values of the parallel capacitor (C 0 ) according to the system operating angular frequency (ω), and the input inductor (L e ), and a calculation expression is as follows:
C
0
=
1
(
1.292
ω
)
2
L
e
.
(
12
)
2 . The design method according to claim 1 , wherein a value of the input inductor (L e ) is 1 nH-500 μH.
3 . The design method according to claim 1 , wherein the Class-E inverter inverts the DC into the high-frequency AC with constant voltage output, and a transformation ratio of an inverting process is calculated by Formula (1):
V
E
V
in
=
1.124
;
(
1
)
wherein V in is a voltage of an input DC power supply, and V E is an effective value of an output high-frequency AC.
4 . The design method according to claim 1 , wherein the CL network or the series resonant unit converts the high-frequency AC with a constant voltage output of the Class-E inverter into a constant current output, and a transformation ratio of the Type I is calculated by Formula (2), and a transformation ratio of the Type II is calculated by Formula (3):
I
cc
V
E
=
1
ω
L
r
,
(
2
)
I
cc
V
E
=
1
ω
M
;
(
3
)
wherein I cc is an effective value of a high-frequency output current, and ω is an operating angular frequency.
5 . The design method according to claim 1 , wherein the series resonant unit or the CL network converts a constant current input into a constant voltage output, and a transformation ratio of the Type I is calculated by Formula (4), and a transformation ratio of the Type II is calculated by Formula (5):
V
cv
I
cc
=
ω
M
,
(
4
)
V
cv
I
cc
=
ω
L
r
;
(
5
)
wherein V cv is an effective value of an output constant voltage.
6 . The design method according to claim 1 , wherein the rectifier circuit is composed of two or four diodes.
7 . The design method according to claim 6 , wherein any one of the two or four diodes is selected from a SIC diode, a Si diode, and a Schottky diode.
8 . The design method according to claim 1 , wherein a structure of the transmitting inductor (L T ) and the receiving inductor (L R ) is a wireless power transfer coil or a high-frequency magnetic core transformer.