Power converter with controllable DC offset
An electrical power conversion system includes an alternating current (AC)-to-direct current (DC) power converter that is configured to convert power between AC power and DC power. The AC-to-DC power converter includes switching legs that each connect to a phase of the AC power. Each of the switching legs includes two electronic devices connected in series with one another between a positive DC bus terminal and a negative DC bus terminal. The electrical power conversion system also includes a DC-to-DC power converter that is configured to convert power between the DC bus power and DC terminal power via a positive DC terminal and a negative DC terminal. The DC-to-DC power converter is configured to control a differential voltage between the positive and negative DC terminals and a common-mode voltage that is between a neutral of the AC power and each of the positive and negative DC terminals.
1. An electrical power conversion system, comprising:
a DC-to-DC power converter configured to receive a DC input power and provide a DC output power, the DC-to-DC power converter including:
a positive input terminal;
a negative input terminal;
an input switch bank including a first switching leg and a second switching leg, wherein each of the first switching leg and the second switching leg is electrically connected directly across the positive input terminal and the negative input terminal;
an output switch bank including a third switching leg and a fourth switching leg;
a positive secondary DC bus terminal extending between the input switch bank and the output switch bank;
a negative secondary DC bus terminal extending between the input switch bank and the output switch bank;
a positive output terminal extending from the output switch bank; and
a negative output terminal extending from the output switch bank;
wherein the positive secondary DC bus terminal is electrically connected to the first switching leg of the input switch bank;
wherein the negative secondary DC bus terminal is electrically connected to the second switching leg of the input switch bank;
wherein each of the third switching leg and the fourth switching leg is electrically connected across the positive secondary DC bus terminal and the negative secondary DC bus terminal without any intervening switching legs positioned between (i) the first switching leg and the second switching leg of the input switch bank and (ii) the third switching leg and the fourth switching leg of the output switch bank;
wherein the positive output terminal is electrically connected to the third switching leg of the output switch bank; and
wherein the negative output terminal is electrically connected to the fourth switching leg of the output switch bank.
2. The electrical power conversion system of claim 1 , wherein the DC-to-DC power converter includes at least one filtering element positioned between the input switch bank and the output switch bank, the at least one filtering element including at least one of (i) one or more capacitors or (ii) one or more inductors.
3. The electrical power conversion system of claim 1 , wherein the DC-to-DC power converter includes at least one of (i) a first inductor positioned in series with the positive input terminal, (ii) a second inductor positioned in series with the negative input terminal, (iii) a third inductor positioned in series with the positive output terminal, or (iv) a fourth inductor positioned in series with the negative output terminal.
4. The electrical power conversion system of claim 3 , wherein the DC-to-DC power converter includes at least one of (i) the first inductor and the second inductor or (ii) the third inductor and the fourth inductor.
5. The electrical power conversion system of claim 1 , wherein the DC-to-DC power converter includes:
at least one first capacitor positioned between the positive input terminal and the negative input terminal; and
at least one second capacitor positioned between the positive output terminal and the negative output terminal.
6. An electrical power conversion system, comprising:
a DC-to-DC power converter configured to receive a DC input power and provide a DC output power, the DC-to-DC power converter including:
a positive input terminal;
a negative input terminal, the positive input terminal and the negative input terminal configured to interface with a power source;
an input switch bank including a first switching leg and a second switching leg, wherein each of the first switching leg and the second switching leg is electrically connected directly across the positive input terminal and the negative input terminal without any intervening switching legs positioned between (i) the first switching leg and the second switching leg and (ii) the power source;
an output switch bank including a third switching leg and a fourth switching leg, wherein each of the first switching leg, the second switching leg, the third switching leg, and the fourth switching legs includes a switch;
a positive secondary DC bus terminal extending between the input switch bank and the output switch bank;
a negative secondary DC bus terminal extending between the input switch bank and the output switch bank;
a positive output terminal extending from the output switch bank; and
a negative output terminal extending from the output switch bank, the positive output terminal and the negative output terminal configured to interface with a load;
wherein each of the third switching leg and the fourth switching leg is electrically connected across the positive output terminal and the negative output terminal without any intervening switching legs positioned between (i) the third switching leg and the fourth switching leg and (ii) the load;
wherein the first switching leg is electrically connected to the fourth switching leg via the positive secondary DC bus terminal; and
wherein the second switching leg is electrically connected to the third switching leg via the negative secondary DC bus terminal.
7. The electrical power conversion system of claim 6 ,
wherein the DC-to-DC power converter includes a filtering element electrically connected between the positive secondary DC bus terminal and the negative secondary DC bus terminal, the filtering element including at least one capacitor.
8. The electrical power conversion system of claim 6 , wherein the DC-to-DC power converter includes at least one of (i) a first inductor positioned between the first switching leg and the positive secondary DC bus terminal or (ii) a second inductor positioned between the second switching leg and the negative secondary DC bus terminal.
9. The electrical power conversion system of claim 8 , wherein the DC-to-DC power converter includes the first inductor and the second inductor.
10. The electrical power conversion system of claim 6 , wherein the DC-to-DC power converter includes at least one capacitor connected between the positive input terminal and the negative input terminal.
11. The electrical power conversion system of claim 10 , wherein the at least one capacitor includes two capacitors connected in series with one another between the positive input terminal and the negative input terminal, and wherein a ground is electrically connected between the two capacitors connected in series.
12. An electrical power conversion system, comprising:
a DC-to-DC power converter configured to receive a DC input power and provide a DC output power, the DC-to-DC power converter comprising:
a positive input terminal;
a negative input terminal;
a positive secondary DC bus terminal;
a negative secondary DC bus terminal;
a first switching leg extending directly between the positive input terminal and the negative input terminal, the first switching leg including a first switch in series with a second switch, the first switching leg connected to the positive secondary DC bus terminal;
a second switching leg extending between the positive input terminal and the negative input terminal, the second switching leg including a third switch in series with a fourth switch, the second switching leg connected to the negative secondary DC bus terminal;
a first inductor positioned between the first switching leg and the positive secondary DC bus terminal;
a second inductor positioned between the second switching leg and the negative secondary DC bus terminal; and
a filtering element electrically connected between the positive input terminal and the negative input terminal, the filtering element including a capacitor.
13. The electrical power conversion system of claim 12 , further comprising a second capacitor electrically connected between the positive secondary DC bus terminal and the negative secondary DC bus terminal.