3-phase high-power UPS
A 3-phase uninterruptible power supply (UPS) including first, second, and third AC/DC converters, a DC/DC converter, and at least one DC/AC converter coupled to multiple electrical buses. The first, second, and third AC/DC converters each being configured to receive AC power and to provide multiple DC signals to the multiple electrical buses. The DC/DC converter being configured to convert DC voltages present on the multiple electrical buses to a DC voltage that can be used to charge a battery. The DC/AC converter being configured to receive DC power from the multiple electrical buses and to provide an AC output. The 3-phase UPS being configured such that when suitable AC power is provided to the AC/DC converters, the DC/DC converter is configured to charge a battery, and when suitable AC power is not provided to the AC/DC converters, the DC/DC converter is configured to provide DC power to the multiple electrical buses using power provided by the battery.
1. A DC/AC converter configured to convey an AC power signal having a positive peak voltage and a negative peak voltage, the DC/AC converter comprising:
an output configured to convey the AC power signal;
first, second, third, and fourth inputs, each being configured to receive a respective input voltage;
a filter coupled to the output;
first and second switches coupled in series between the filter and the first input, the first switch being coupled to the filter;
a third switch coupled to a junction of the first and second switches and the second input;
fourth and fifth switches coupled in series between the filter and the fourth input, the fourth switch being coupled to the filter;
a sixth switch coupled to a junction of the fourth and fifth switches and the third input;
a first diode coupled in parallel with the first switch;
a second diode coupled in parallel with the second switch;
a third diode coupled in parallel with the third switch;
a fourth diode coupled in parallel with the fourth switch;
a fifth diode coupled in parallel with the fifth switch; and
a sixth diode coupled in parallel with the sixth switch.
2. The DC/AC converter of claim 1 further comprising a controller coupled to the first, second, third, fourth, fifth, and sixth switches.
3. The DC/AC converter of claim 2 wherein the controller is configured to toggle the first, second, third, fourth, fifth, and sixth switches such that the AC power signal is induced at the output.
4. The DC/AC converter of claim 3 wherein the controller is configured to toggle the first, second, third, fourth, fifth, and sixth switches such that:
the positive peak voltage of the output AC power signal is less than the DC voltage conveyed to the first input multiplied by
3
2
;
and
the negative peak voltage of the output AC power signal is greater than the DC voltage conveyed to the fourth input multiplied by
3
2
.
5. The DC/AC converter of claim 4 wherein the controller is configured to:
cause, when the AC power signal is between the DC voltages conveyed on the first and second inputs, the DC/AC converter to operate in a first state where:
the first switch is toggled on;
the second switch is repeatedly toggled on and off;
the third switch is repeatedly toggled on and off;
the fourth switch is toggled off;
the fifth switch is toggled off;
the sixth switch is toggled on;
cause, when the AC power signal is between the DC voltages conveyed on the second and third inputs, the DC/AC converter to operate in a second state where:
the first switch is repeatedly toggled on and off;
the second switch toggled off;
the third switch is toggled on;
the fourth switch is repeatedly toggled on and off;
the fifth switch is toggled off;
the sixth switch is toggled on;
cause, when the AC power signal is between the DC voltages conveyed on the third and fourth inputs, the DC/AC converter to operate in a third state where:
the first switch is toggled off;
the second switch toggled off;
the third switch is toggled on;
the fourth switch is toggled on;
the fifth switch is repeatedly toggled on and off; and
the sixth switch is repeatedly toggled on and off.
6. The DC/AC converter of claim 1 wherein the filter comprises:
an inductor coupled between the output and the junction of first and fourth switches; and
a capacitor coupled between the output and a neutral.
7. The DC/AC converter of claim 1 wherein the first, second, third, fourth, fifth, and sixth switches are configured to be controlled by a pulse width modulation (PWM) controller.
8. The DC/AC converter of claim 7 wherein the PWM controller coupled to the output and configured to control the actuation of the first, second, third, fourth, fifth, and sixth switches in accordance with a voltage level of the output.
9. The AC/DC converter of claim 1 further comprising:
a first capacitor coupled between the first and second inputs;
a second capacitor coupled between the second input and a neutral;
a third capacitor coupled between the neutral and the third input; and
a fourth capacitor coupled between the third and fourth inputs.