Voltage conversion circuit, charging apparatus, and electric device
A voltage conversion circuit includes an N-level conversion unit and N−1 DC-DC conversion units. The N-level conversion unit includes N output terminals at different levels. A first input terminal of an M th DC-DC conversion unit is connected to an M th output terminal of the N-level conversion unit, and a second input terminal of the M th DC-DC conversion unit is connected to an (M+1) th output terminal of the N-level conversion unit. An output level of the M th output terminal and an output level of the (M+1) th output terminal are adjacent levels. N and M are positive integers and satisfy N≥3 and 1≤M<N.
1. A voltage conversion circuit, comprising:
an N-level conversion unit, comprising N output terminals at different levels;
N−1 DC-DC conversion units, wherein a first input terminal of an M th DC-DC conversion unit is connected to an M th output terminal of the N-level conversion unit, a second input terminal of the M th DC-DC conversion unit is connected to an (M+1) th output terminal of the N-level conversion unit, and an output level of the M th output terminal and an output level of the (M+1) th output terminal are adjacent levels; and
a control unit connected to the N-level conversion unit and the N−1 DC-DC conversion units, wherein the control unit is configured to:
obtain an output voltage of each of the DC-DC conversion units, obtain a reference voltage based on the output voltages of the DC-DC conversion units, compare the output voltages of the DC-DC conversion units with the reference voltage one after another to obtain voltage differences each corresponding to one of the output voltages of the DC-DC conversion units, and control an intermediate output level of the N-level conversion unit based on the voltage differences; or
obtain an output current of each of the DC-DC conversion units, obtain a reference current based on the output currents of the DC-DC conversion units, compare the output currents of the DC-DC conversion units with the reference current one after another to obtain current differences each corresponding to one of the output currents of the DC-DC conversion units, and control the intermediate output level of the N-level conversion unit based on the current differences;
wherein N and M are positive integers and satisfy N≥3 and 1≤M<N.
2. The voltage conversion circuit according to claim 1 , wherein:
each of the N−1 DC-DC conversion units includes a first output terminal and a second output terminal;
a first output terminal of a first DC-DC conversion unit is connected to a first node, a first output terminal of the P th DC-DC conversion unit is connected to a second output terminal of the (P−1) th DC-DC conversion unit, and a second output terminal of the (N−1) th DC-DC conversion unit is connected to a second node; and
P is a positive integer and satisfies 2≤P<N.
3. The voltage conversion circuit according to claim 2 , wherein:
N=3, the N-level conversion unit comprises a three-level conversion unit, and the N−1 DC-DC conversion units comprise the first DC-DC conversion unit and a second DC-DC conversion unit;
the three-level conversion unit comprises a first output terminal, a second output terminal, and a third output terminal with levels decreasing sequentially;
a first input terminal of the first DC-DC conversion unit is connected to the first output terminal of the three-level conversion unit, a second input terminal of the first DC-DC conversion unit and a first input terminal of the second DC-DC conversion unit are connected to the second output terminal of the three-level conversion unit, and a second input terminal of the second DC-DC conversion unit is connected to the third output terminal of the three-level conversion unit; and
the first output terminal of the first DC-DC conversion unit is connected to the first node, a second output terminal of the first DC-DC conversion unit is connected to the first output terminal of the second DC-DC conversion unit, and the second output terminal of the second DC-DC conversion unit is connected to the second node.
4. The voltage conversion circuit according to claim 3 , wherein the three-level conversion unit is a single-phase I-type three-level conversion unit, a three-phase I-type three-level conversion unit, a single-phase T-type three-level conversion unit, or a three-phase T-type three-level conversion unit.
5. The voltage conversion circuit according to claim 4 ,
wherein the three-level conversion unit is a first three-level conversion unit;
the voltage conversion circuit further comprising:
a second three-level conversion unit, a third DC-DC conversion unit, and a fourth DC-DC conversion unit;
wherein:
levels of a first output terminal, a second output terminal, and a third output terminal of the second three-level conversion unit decrease sequentially;
a first input terminal of the third DC-DC conversion unit is connected to the first output terminal of the second three-level conversion unit, a second input terminal of the third DC-DC conversion unit and a first input terminal of the fourth DC-DC conversion unit are connected to the second output terminal of the second three-level conversion unit, and a second input terminal of the fourth DC-DC conversion unit is connected to the third output terminal of the second three-level conversion unit; and
the first output terminal of the first DC-DC conversion unit and a first output terminal of the fourth DC-DC conversion unit are connected to a third node, and a second output terminal of the third DC-DC conversion unit and a second output terminal of the fourth DC-DC conversion unit are connected to a fourth node.
6. The voltage conversion circuit according to claim 5 , wherein the second three-level conversion unit is a single-phase I-type three-level conversion unit, a three-phase I-type three-level conversion unit, a single-phase T-type three-level conversion unit, or a three-phase T-type three-level conversion unit.
7. The voltage conversion circuit according to claim 1 , wherein a first output terminal of each of the N−1 DC-DC conversion units is connected to a first node, and a second output terminal of each of the N−1 DC-DC conversion units is connected to a second node.
8. The voltage conversion circuit according to claim 1 , wherein input terminals of the N-level conversion unit are connected to a single-phase alternating current power supply or a three-phase alternating current power supply.
9. The voltage conversion circuit according to claim 1 , wherein each of the N−1 DC-DC conversion units is an LLC circuit, a CLLLC circuit, or a phase-shifting full-bridge converter (PSFB) circuit.
10. The voltage conversion circuit according to claim 1 , wherein the control unit is further configured to:
control output levels of the N-level conversion unit, so that a difference between the output voltages of the DC-DC conversion units is less than or equal to a first threshold; or
control the output levels of the N-level conversion unit, so that a difference between the output currents of the DC-DC conversion units is less than or equal to a second threshold.
11. The voltage conversion circuit according to claim 1 , wherein the intermediate output level is between a maximum output level of the N-level conversion unit and a minimum output level of the N-level conversion unit.
12. A charging apparatus, comprising a voltage conversion circuit comprising:
an N-level conversion unit, comprising N output terminals at different levels; and
N−1 DC-DC conversion units, wherein a first input terminal of an M th DC-DC conversion unit is connected to an M th output terminal of the N-level conversion unit, a second input terminal of the M th DC-DC conversion unit is connected to an (M+1) th output terminal of the N-level conversion unit, and an output level of the M th output terminal and an output level of the (M+1) th output terminal are adjacent levels; and
a control unit connected to the N-level conversion unit and the N−1 DC-DC conversion units, wherein the control unit is configured to:
obtain an output voltage of each of the DC-DC conversion units, obtain a reference voltage based on the output voltages of the DC-DC conversion units, compare the output voltages of the DC-DC conversion units with the reference voltage one after another to obtain voltage differences each corresponding to one of the output voltages of the DC-DC conversion units, and control an intermediate output level of the N-level conversion unit based on the voltage differences; or
obtain an output current of each of the DC-DC conversion units, obtain a reference current based on the output currents of the DC-DC conversion units, compare the output currents of the DC-DC conversion units with the reference current one after another to obtain current differences each corresponding to one of the output currents of the DC-DC conversion units, and control the intermediate output level of the N-level conversion unit based on the current differences;
wherein N and M are positive integers and satisfy N≥3 and 1≤M<N.
13. An electric device, comprising a charging apparatus comprising a voltage conversion circuit, the voltage conversion circuit comprising:
an N-level conversion unit, comprising N output terminals at different levels; and
N−1 DC-DC conversion units, wherein a first input terminal of an M th DC-DC conversion unit is connected to an M th output terminal of the N-level conversion unit, a second input terminal of the M th DC-DC conversion unit is connected to an (M+1) th output terminal of the N-level conversion unit, and an output level of the M th output terminal and an output level of the (M+1) th output terminal are adjacent levels; and
a control unit connected to the N-level conversion unit and the N−1 DC-DC conversion units, wherein the control unit is configured to:
obtain an output voltage of each of the DC-DC conversion units, obtain a reference voltage based on the output voltages of the DC-DC conversion units, compare the output voltages of the DC-DC conversion units with the reference voltage one after another to obtain voltage differences each corresponding to one of the output voltages of the DC-DC conversion units, and control an intermediate output level of the N-level conversion unit based on the voltage differences; or
obtain an output current of each of the DC-DC conversion units, obtain a reference current based on the output currents of the DC-DC conversion units, compare the output currents of the DC-DC conversion units with the reference current one after another to obtain current differences each corresponding to one of the output currents of the DC-DC conversion units, and control the intermediate output level of the N-level conversion unit based on the current differences;
wherein N and M are positive integers and satisfy N≥3 and 1≤M<N.