Balanced switching amplifier for a magnetic bearing assembly

A magnetic bearing assembly for a rotating machine, comprising:

• a rotor configured to rotate with a rotary shaft of the rotating machine;
• a plurality of electromagnets disposed about the rotor, each electromagnet comprising a first coil and a second coil spaced from the first coil;
• a plurality of balanced switching amplifiers, each balanced switching amplifier electrically coupled to a respective electromagnet via four lead wires, wherein two lead wires of the four lead wires are electrically coupled to the first coil and two other lead wires of the four lead wires are electrically coupled to the second coil;
• a plurality of sensors configured to measure at least one of an axial position and a radial position of the rotor, each sensor further configured to generate and transmit an input signal including information related to a measured position of the rotor;
• a controller configured to receive the respective input signal from each of the sensors, compare the respective received input signal with a first reference signal and a second reference signal, generate a first output signal and a second output signal based on a comparison of the respective received input signal with the first reference signal and the second reference signal, and transmit the first output signal and the second output signal to the respective balanced switching amplifier of the plurality of balanced switching amplifiers;
• and
• a power source electrically coupled to and configured to power at least the plurality of balanced switching amplifiers, wherein each balanced switching amplifier comprises:
• a voltage link receiving a voltage from the power source and configured to provide a positive voltage link and a negative voltage link;
• a first switching amplifier electrically coupled to the first coil of the electromagnet via the first two lead wires, the first switching amplifier comprising
• a first switch electrically coupled to the positive voltage link;
• and
• a second switch electrically coupled to the negative voltage link, wherein the first switch and the second switch are configured to output four distinct output states for the first switching amplifier;
• and
• a second switching amplifier electrically coupled to the second coil of the electromagnet via the two other lead wires, the second switching amplifier comprising
• a third switch electrically coupled to the positive voltage link;
• and
• a fourth switch electrically coupled to the negative voltage link, wherein the third switch and the fourth switch are configured to output four distinct output states for the second switching amplifier,
• wherein the first switching amplifier and the second switching amplifier are configured to operate in tandem such that respective voltages in the two lead wires and the two other lead wires substantially neutralize one another, thereby reducing electromagnetic emissions from each of the four lead wires.

A magnetic bearing assembly for a rotating machine, comprising:

• a rotor configured to rotate with a rotary shaft of the rotating machine;
• a plurality of electromagnets disposed about the rotor and comprising a first electromagnet comprising a first coil and a second electromagnet radially opposing the first electromagnet and comprising a second coil;
• a plurality of switching amplifiers configured to operate in synchrony with one another, the plurality of switching amplifiers comprising a first switching amplifier electrically coupled to the first coil of the first electromagnet via two lead wires, and a second switching amplifier electrically coupled to the second coil of the second electromagnet via two other lead wires;
• a plurality of sensors configured to measure at least one of an axial position and a radial position of the rotor, each sensor further configured to generate and transmit an input signal including information related to a measured position of the rotor;
• a controller configured to receive the respective input signal from each of the sensors, compare the respective received input signal with a first reference signal and a second reference signal, generate a first output signal and a second output signal based on a comparison of the respective received input signal with the first reference signal and the second reference signal, and transmit the first output signal to the first switching amplifier and the second output signal to the second switching amplifier of the plurality of switching amplifiers;
• and
• a power source electrically coupled to and configured to power at least the plurality of switching amplifiers,
• wherein:
• the first switching amplifier and the second switching amplifier each comprises a voltage link receiving a voltage from the power source and configured to provide a positive voltage link and a negative voltage link;
• the first switching amplifier comprises
• a first switch electrically coupled to the positive voltage link;
• and
• a second switch electrically coupled to the negative voltage link, wherein the first switch and the second switch are configured to output four distinct output states for the first switching amplifier;
• the second switching amplifier comprises
• a third switch electrically coupled to the positive voltage link;
• and
• a fourth switch electrically coupled to the negative voltage link, wherein the third switch and the fourth switch are configured to output four distinct output states for the second switching amplifier;
• and
• the first switching amplifier and the second switching amplifier are configured to operate in tandem such that respective voltages in the two lead wires and the two other lead wires substantially neutralize one another, thereby reducing electromagnetic emissions from each of the four lead wires.