DC-DC converter assembly
A DC-DC converter assembly includes a DC-DC power converter. A converter load is electrically connected between a positive input and a positive output (or negative input and negative output) of the DC-DC converter such that a DC input voltage source of the assembly supplies load power directly to the converter load without passing through the DC-DC power converter.
1. A DC-DC converter assembly comprising:
a DC-DC power converter configured to convert a DC input voltage supplied by a DC input voltage source into a DC output voltage in accordance with at least first and second modulated control signals, and
a converter load electrically connected in series with the DC-DC power converter such that the DC input voltage source supplies power directly to the converter load without passing through the DC-DC power converter;
said DC-DC power converter comprising:
a control circuit configured to adjust the DC output voltage or current in accordance with a target DC voltage or a DC target current, respectively, and
a configurable switch network configured to switch the DC-DC power converter between:
a first operational mode for generating a DC output voltage of a first polarity using a first current charge path and first current discharge path of the configurable switch network to provide a converter load voltage smaller than the DC input voltage, the generating the DC output voltage of the first polarity comprising selectively charging an inductor from the DC output voltage through a first switch in accordance with the first modulated control signal and discharging the inductor into the input of the DC-DC power converter through a second switch in accordance with the second modulated control signal, and
a second operational mode for generating a DC output voltage of a second polarity, opposite to the first polarity, using a second current charge path and second current discharge path of the configurable switch network to provide a converter load voltage that is larger than the DC input voltage, the generating the DC output voltage of the second polarity comprising charging the inductor from the DC input voltage through a third switch in accordance with one of the first or second modulated control signals and discharging the inductor into the DC output voltage in accordance with the other of the first or second modulated control signals.
2. The DC-DC converter assembly according to claim 1 , wherein the control circuit is configured to switch the configurable switch network between the first operational mode and second operational mode depending on the target DC voltage or target DC current, the DC input voltage and the DC output voltage.
3. The DC-DC converter assembly according to claim 1 , wherein the configurable switch network comprises a plurality of interconnected individually controllable semi-conductor switches configured to:
during the first operational mode:
selectively charge the inductor from the DC output voltage through a first controllable semiconductor switch in accordance with the first modulated control signal and discharge the inductor into the input of the DC-DC power converter through a second controllable semiconductor switch in accordance with the second, and complimentary, modulated control signal, and
placing a third controllable semiconductor switch constantly in a non-conducting state and placing a fourth controllable semiconductor switch constantly in a conducting state; and
during the second operational mode:
placing the first and second controllable semiconductor switches constantly in a conducting state and non-conducting state, respectively, and
charging the inductor from the DC input voltage through the third controllable semi-conductor switch in accordance with the one of the first or second complimentary modulated control signals and discharge the inductor into the first or second polarity DC output voltage in accordance with the other one of first and second complimentary modulated control signals.
4. The DC-DC converter assembly according to claim 3 , wherein the control circuit comprises a modulator configured to generate the first or second complimentary modulated control signals at respective outputs of first and second comparators of the modulator; said modulator comprising:
a carrier signal generator configured to generate first and second mutually offset carrier signals at a switching frequency of the DC-DC power converter,
the first comparator having a first input connected to the first carrier signal and second input connected to a dynamic reference signal; and
the second comparator having a first input connected to the second carrier signal and a second input connected to the dynamic reference signal;
wherein the control circuit is configured to switch between first and second operational modes by adjusting a voltage or level of the dynamic reference signal.
5. The DC-DC converter assembly according to claim 4 , wherein the control circuit is configured to adjust the voltage or level of the dynamic reference signal at a predetermined control frequency, within a predetermined intermediate output voltage region around 0 V of the DC-DC power converter; said control frequency being at least 3 times smaller than the switching frequency of the DC-DC power converter.
6. The DC-DC converter assembly according to claim 1 , wherein the DC-DC power converter comprises:
at least one capacitor connected between the positive input and positive output of the DC-DC power converter; or
an input capacitor connected between the positive input and negative input of the DC-DC power converter and an output capacitor connected between the positive output and negative output of the DC-DC power converter.
7. The DC-DC converter assembly according to claim 1 , wherein the DC-DC power converter is configured to operate in current continuous conduction mode.
8. The DC-DC converter assembly according to claim 3 , wherein the configurable switch network is electrically connected between an input and an output of the DC-DC power converter.
9. The DC-DC converter assembly according to claim 3 , wherein the configurable switch network further comprises:
a first passive diode connected in series with the inductor and the first controllable semiconductor switch between the positive and negative outputs of the DC-DC pow er converter to provide, during the first and second operational modes, a first charge path for charging the inductor in accordance with the first modulated control signal; and
a second passive diode coupled in series with the inductor and the second controllable semiconductor switch to the positive input the DC-DC power converter to pro-vide, during at least the first operational mode, the first discharge path for discharging the inductor in accordance with the second modulated control signal.
10. The DC-DC converter assembly according to claim 3 , wherein the configurable switch network further comprises:
a first active diode, for example comprising a fourth controllable semiconductor switch, connected in series with the inductor and the first controllable semiconductor switch between the positive and negative outputs of the DC-DC power converter to provide, during the first and second operational modes, a first charge path for charging the inductor in accordance with first modulated control signal; and
a second active diode, for example comprising a fifth controllable semiconductor switch, coupled in series with the inductor and the second controllable semiconductor switch to the positive input the DC-DC power converter to provide, during at least the first operational mode, a first discharge path for discharging the inductor during the second phase of the modulated control signal.
11. The DC-DC converter assembly according to claim 3 , wherein the DC-DC power converter further comprises:
a resonant DC-DC converter stage coupled in series with the positive input of the DC-DC power converter and configured to step-up the DC input voltage with a predetermined boost factor.
12. The DC-DC converter assembly according to claim 11 , wherein the resonant DC-DC converter stage comprises:
a first full-bridge or half-bridge rectifier coupled between the DC input voltage of the DC-DC power converter and a primary side winding of a transformer; and
a second full-bridge or half-bridge rectifier coupled between a secondary side winding of the transformer and the input voltage of the configurable switch network.
13. The DC-DC converter assembly according to claim 1 , wherein at least one of the converter load and the DC input voltage source comprises an inverter or a battery pack with a plurality of rechargeable battery cells.
14. The DC-DC converter assembly according to claim 13 , wherein at least one of the converter load and the DC input voltage source comprises an inverter connectable to a single phase mains grid or a multi-phase mains grid.
15. The DC-DC converter assembly according to claim 1 , wherein the DC-DC power converter is configured for bidirectional operation to additionally transfer power from the converter load directly to the DC input voltage source without passing through the power DC-DC converter.
16. A method of supplying power to a converter load of a DC-DC converter assembly using a DC-DC power converter, comprising:
connecting a DC input voltage source to an input of the DC-DC power converter to provide a DC input voltage thereto,
adjusting a DC output voltage or current at an output of the DC-DC power converter by a control circuit in accordance with the DC input voltage, the DC output voltage and a target DC voltage or target DC current, respectively;
selectively switching a configurable switch network of the DC-DC power converter between:
a first operational mode for generating a first polarity DC output voltage to provide a converter load voltage smaller than the DC input voltage, the generating the first polarity DC output voltage comprising selectively charging an inductor from the DC output voltage through a first switch in accordance with a first modulated control signal and discharging the inductor into the input of the DC-DC power converter through a second switch in accordance with a second modulated control signal; and
a second operational mode for generating a second polarity, opposite to the first polarity, DC output voltage to provide a converter load voltage larger than the DC input voltage, the generating the second polarity DC output comprising charging the inductor from the DC input voltage through a third switch in accordance with one of the first modulated control signal or the second modulated control signal and discharging the inductor into the DC output voltage in accordance with the other of the first modulated control signal or the second modulated control signal.
17. The method of supplying power to a converter load of a DC-DC converter assembly using a DC-DC power converter according to claim 16 , further comprising:
during the first operational mode: charging the inductor from the DC output voltage through a first controllable semiconductor switch in accordance with the first modulated control signal and discharging the inductor into the input of the DC-DC power converter in accordance with the second modulated control signal, and
switching a third controllable semiconductor switch constantly to a non-conducting state; and
during the second operational mode: maintaining the first and second controllable semiconductor switches constantly in a conducting state and non-conducting state, respectively, and
charging the inductor from the DC input voltage through the third controllable semi-conductor switch in accordance with the first modulated control signal and discharging the inductor, through the negative output, into the first or second polarity output of the DC-DC power converter in accordance with the second modulated control signal.