Power supply for supplying multi-channel, stable, isolated DC power and method of making same
A power supply having an input, wherein the power supply includes a multi-winding transformer having an input and a plurality of outputs, and a plurality of rectifiers to provide a plurality of DC output voltages, wherein each rectifier is coupled to an output of the multi-winding transformer. The power supply further includes a regulator circuit coupled between the transformer input and one of the transformer outputs, and configured to regulate an input voltage to the multi-winding transformer to minimize a variance of each rectifier DC output voltage.
1. A power supply having an input, the power supply comprising:
a multi-winding transformer having an input and a plurality of outputs;
a plurality of rectifiers to provide a plurality of DC output voltages, wherein each rectifier is coupled to an output of the multi-winding transformer; and
a regulator circuit coupled between the transformer input and one of the outputs, and configured to regulate an input voltage to the multi-winding transformer to minimize a variance of each rectifier DC output voltage, wherein the regulator circuit comprises:
an inductive filter coupled to an output of the transformer;
an active rectifier coupled to the inductive filter;
an inverter coupled to the active rectifier;
a capacitor connected across an output of the active rectifier;
an LC filter coupled to the inverter; and
a bypass protection circuit coupled between the LC filter and the power supply input.
2. The power supply of claim 1 wherein the inverter comprises a pulse-width-modulated inverter.
3. The power supply of claim 1 wherein the inductive filter comprises leakage inductance from the multi-winding transformer.
4. The power supply of claim 1 wherein the regulator circuit further comprises a second transformer to electrically isolate the power supply input from the plurality of transformer outputs.
5. The power supply of claim 1 wherein the power supply is configured to accept a three-phase AC input voltage.
6. The power supply of claim 1 wherein the power supply is configured to accept a single-phase AC input voltage.
7. The power supply of claim 1 wherein the regulator circuit is further configured to add a compensating voltage to the input voltage to the multi-winding transformer.
8. An MRI apparatus comprising:
a magnetic resonance imaging (MRI) system having a plurality of gradient coils positioned about a bore of a magnet, a plurality of gradient amplifiers, an RF transceiver system, an RF switch controlled by a pulse module to transmit RF signals to an RF coil assembly to acquire MR images, a DC power supply having an input and coupled to the plurality of gradient amplifiers, the power supply comprising:
a transformer having a primary winding and a plurality of secondary windings;
a rectifier array coupled to at least a portion of the plurality of secondary windings and configured to provide a plurality of DC outputs therefrom; and
a control circuit electrically coupled between the primary winding and one of the secondary windings, and configured to regulate an input voltage to the primary winding to minimize a variance of each DC output, wherein the control circuit comprises:
an inductive filter coupled to a secondary winding of the transformer;
an active rectifier coupled to the inductive filter;
an inverter coupled to the active rectifier;
a capacitor connected across an output of the active rectifier;
an LC filter coupled to the inverter; and
a bypass protection circuit coupled between the LC filter and the power supply input.
9. The MRI apparatus of claim 8 wherein the input voltage to the primary winding is regulated by the addition of a compensating voltage to the input voltage to the primary winding of the transformer.
10. The MRI apparatus of claim 8 wherein the inverter comprises a pulse-width-modulated inverter.
11. The MRI apparatus of claim 8 wherein the control circuit further comprises a second transformer to electrically isolate the power supply input from the plurality of secondary windings.
12. The MRI apparatus of claim 8 wherein the power supply is further configured to accept a three-phase AC input voltage.
13. A method of manufacturing a power supply comprising:
providing a connection and electrical line for an AC input;
coupling the AC input to a multi-winding transformer having a plurality of outputs;
assembling a plurality of rectifiers to the multi-winding transformer wherein each rectifier is coupled to an output of the multi-winding transformer;
assembling a regulator circuit coupled to one of the transformer outputs; and
coupling the regulator circuit to the electrical line for the AC input, wherein assembly of the regulator circuit comprises:
coupling an active rectifier to an output of the multi-winding transformer;
coupling an inverter to the active rectifier;
connecting a capacitor across an output of the active rectifier;
coupling an LC filter to the inverter; and
coupling a bypass protection circuit between the LC filter and the power supply input.
14. The method of claim 13 wherein providing a connection and electrical line for an AC input comprises providing a three-phase connection and electrical line.
15. The method of claim 13 wherein the inverter comprises a pulse-width-modulated inverter.
16. The method of claim 13 further comprising coupling a second transformer between the bypass protection circuit and the power supply input.
17. The method of claim 13 further comprising coupling an inductive filter between the output of the multi-winding transformer and the active rectifier.